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There is an ongoing need of developing sensitive and specific methods for the determination of SARS-CoV-2 seroconversion. For this purpose, we have developed a multiplexed flow cytometric bead array (C19BA) that allows the identification of IgG and IgM antibodies against three immunogenic proteins simultaneously: the spike receptor-binding domain (RBD), the spike protein subunit 1 (S1) and the nucleoprotein (N). Using different cohorts of samples collected before and after the pandemic, we show that this assay is more sensitive than ELISAs performed in our laboratory. The combination of three viral antigens allows for the interrogation of full seroconversion. Importantly, we have detected N-reactive antibodies in COVID-19-negative individuals. Here we present an immunoassay that can be easily implemented and has superior potential to detect low antibody titers compared to current gold standard serology methods., Egia-Mendikute et al. develop a multiplexed flow cytometric bead array to simultaneously detect antibodies reactive to three immunogenic SARS-CoV-2 proteins. More sensitive than ELISA, they detected N-reactive antibodies in COVID-19-negative individuals with this assay, showing it to have superior potential to detect low antibody titres compared to current gold standard serology methods.

17 páginas, 6 figuras, Background and aims: Hepatic ischemia-reperfusion injury (IRI) is the leading cause of early posttransplantation organ failure as mitochondrial respiration and ATP production are affected. A shortage of donors has extended liver donor criteria, including aged or steatotic livers, which are more susceptible to IRI. Given the lack of an effective treatment and the extensive transplantation waitlist, we aimed at characterizing the effects of an accelerated mitochondrial activity by silencing methylation-controlled J protein (MCJ) in three preclinical models of IRI and liver regeneration, focusing on metabolically compromised animal models. Approach and results: Wild-type (WT), MCJ knockout (KO), and Mcj silenced WT mice were subjected to 70% partial hepatectomy (Phx), prolonged IRI, and 70% Phx with IRI. Old and young mice with metabolic syndrome were also subjected to these procedures. Expression of MCJ, an endogenous negative regulator of mitochondrial respiration, increases in preclinical models of Phx with or without vascular occlusion and in donor livers. Mice lacking MCJ initiate liver regeneration 12 h faster than WT and show reduced ischemic injury and increased survival. MCJ knockdown enables a mitochondrial adaptation that restores the bioenergetic supply for enhanced regeneration and prevents cell death after IRI. Mechanistically, increased ATP secretion facilitates the early activation of Kupffer cells and production of TNF, IL-6, and heparin-binding EGF, accelerating the priming phase and the progression through G1 /S transition during liver regeneration. Therapeutic silencing of MCJ in 15-month-old mice and in mice fed a high-fat/high-fructose diet for 12 weeks improves mitochondrial respiration, reduces steatosis, and overcomes regenerative limitations. Conclusions: Boosting mitochondrial activity by silencing MCJ could pave the way for a protective approach after major liver resection or IRI, especially in metabolically compromised, IRI-susceptible organs.

[Background & Aims] Autophagy-related gene 3 (ATG3) is an enzyme mainly known for its actions in the LC3 lipidation process, which is essential for autophagy. Whether ATG3 plays a role in lipid metabolism or contributes to non-alcoholic fatty liver disease (NAFLD) remains unknown., [Methods] By performing proteomic analysis on livers from mice with genetic manipulation of hepatic p63, a regulator of fatty acid metabolism, we identified ATG3 as a new target downstream of p63. ATG3 was evaluated in liver samples from patients with NAFLD. Further, genetic manipulation of ATG3 was performed in human hepatocyte cell lines, primary hepatocytes and in the livers of mice., [Results] ATG3 expression is induced in the liver of animal models and patients with NAFLD (both steatosis and non-alcoholic steatohepatitis) compared with those without liver disease. Moreover, genetic knockdown of ATG3 in mice and human hepatocytes ameliorates p63- and diet-induced steatosis, while its overexpression increases the lipid load in hepatocytes. The inhibition of hepatic ATG3 improves fatty acid metabolism by reducing c-Jun N-terminal protein kinase 1 (JNK1), which increases sirtuin 1 (SIRT1), carnitine palmitoyltransferase 1a (CPT1a), and mitochondrial function. Hepatic knockdown of SIRT1 and CPT1a blunts the effects of ATG3 on mitochondrial activity. Unexpectedly, these effects are independent of an autophagic action., [Conclusions] Collectively, these findings indicate that ATG3 is a novel protein implicated in the development of steatosis., This work has been supported by grants from FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación (PA: RTI2018-095134-B-100; DS and LH: SAF2017-83813-C3-1-R; MLMC: RTC2019-007125-1; CD: BFU2017-87721; ML: RTI2018–101840-B-I00; GS; PID2019-104399RB-I00; RN: RTI2018-099413-B-I00 and RED2018-102379-T; MLMC: SAF2017-87301-R; TCD: RTI2018-096759-A-100), FEDER/Instituto de Salud Carlos III (AGR: PI19/00123), Xunta de Galicia (ML: 2016-PG068; RN: 2015-CP080 and 2016-PG057), Fundación BBVA (RN, GS and MLM), Proyectos Investigación en Salud (MLMC: DTS20/00138), Sistema Universitario Vasco (PA: IT971-16); Fundación Atresmedia (ML and RN), Fundación La Caixa (M.L., R.N. and M.C.), Gilead Sciences International Research Scholars Program in Liver Disease (MVR), Marató TV3 Foundation (DS: 201627), Government of Catalonia (DS: 2017SGR278) and European Foundation for the Study of Diabetes (RN and GS). This research also received funding from the European Community’s H2020 Framework Programme (ERC Synergy Grant-2019-WATCH- 810331, to RN, VP and MS). Centro de Investigación Biomédica en Red (CIBER) de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Centro de Investigación Biomédica en Red (CIBER) de Enfermedades Hepáticas y Digestivas (CIBERehd) and CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERdem). CIBERobn, CIBERehd and CIBERdem are initiatives of the Instituto de Salud Carlos III (ISCIII) of Spain which is supported by FEDER funds. We thank MINECO for the Severo Ochoa Excellence Accreditation to CIC bioGUNE (SEV-2016-0644).

Neuroinvasion by SARS-CoV-2 is now accepted. To investigate whether low testosterone levels observed in men with severe COVID-19 could be of central origin, we retrospectively analyzed blood samples from 60 male intensive-care patients and explored SARS-CoV-2 brain entry using animal and cellular models as well as adult COVID-19 patient and fetal human brains. Most hypotestosteronemic patients displayed hypogonadotropic hypogonadism or abnormal hypothalamic-pituitary-gonadal axis regulation. Neurons producing gonadotropin-releasing hormone (GnRH), the master molecule controlling fertility, expressed angiotensin-converting enzyme 2 and neuropilin-1, two host-cell factors mediating infection, and were infected and dying in all COVID-19 patient brains. Tanycytes - hypothalamic glia that regulate GnRH secretion - were also infected. Additionally, human fetal olfactory and vomeronasal epithelia, from which GnRH neurons arise, richly expressed both the above host-cell susceptibility factors and formyl peptide receptor 2, a putative vomeronasal receptor that also appeared involved in SARS-CoV-2 pathogenesis in humans and mice. Finally, a fetal human GnRH cell line expressing all these receptors could be infected by a SARS-CoV-2-like pseudovirus. Together, our findings suggest that GnRH neurons, which may be implicated in brain development and aging in addition to reproduction, are particularly vulnerable to SARS-CoV-2 in both adults and fetuses/newborns, with potentially devastating long-term consequences.

Liver kinase B1 (LKB1) also referred to as serine/threonine kinase 11 (STK11) encodes a 50 kDa evolutionary conserved serine/threonine kinase that is ubiquitously expressed in adult and fetal tissues. LKB1 is a master kinase known to phosphorylate and activate several kinases including AMP-activated protein kinase, a crucial cellular energy sensor. LKB1 shows pleiotropic activity playing diverse roles in multiple processes, including cell polarity and other processes relevant in cancer pathology, such as energy metabolism, proliferation and apoptosis. In spite of the fact that LKB1 is often considered a tumor suppressor in a wide variety of organs, in the last years, several studies have shown that LKB1 is unexpectedly high in hepatocellular carcinoma (HCC), the most common type of primary liver cancer. Post-translational modifications of LKB1 are potentially relevant in HCC. Herein, we provide a comprehensive revision of post-translational modifications of LKB1 in HCC and how they modulate LKB1 function by different mechanisms such as regulation of its activity, localization or stability. Overall, the signature post-translational modifications of LKB1 in HCC appear to play an important role in the rather unique role of LKB1 as an oncogenic driver in liver cancer and may provide an alternative valuable therapeutic approach to regulate LKB1 expression and/or activity in HCC.

Lyme carditis is an extracutaneous manifestation of Lyme disease characterized by episodes of atrioventricular block of varying degrees and additional, less reported cardiomyopathies. The molecular changes associated with the response to Borrelia burgdorferi over the course of infection are poorly understood. Here, we identify broad transcriptomic and proteomic changes in the heart during infection that reveal a profound down-regulation of mitochondrial components. We also describe the long-term functional modulation of macrophages exposed to live bacteria, characterized by an augmented glycolytic output, increased spirochetal binding and internalization, and reduced inflammatory responses. In vitro, glycolysis inhibition reduces the production of tumor necrosis factor (TNF) by memory macrophages, whereas in vivo, it produces the reversion of the memory phenotype, the recovery of tissue mitochondrial components, and decreased inflammation and spirochetal burdens. These results show that B. burgdorferi induces long-term, memory-like responses in macrophages with tissue-wide consequences that are amenable to be manipulated in vivo., Supported by grants from the Spanish Ministry of Science, Innovation and Universities (MCIU) co-financed with FEDER funds (SAF2015-65327-R and RTI2018-096494-B-100 to JA; BFU2016-76872-R to EB, AGL2017-86757-R to LA, SAF2017-87301-R to MLMC, SAF2015-64111-R to AP, SAF2015-73549-JIN to HR), Instituto de Salud Carlos III (PIE13/0004 to AP), the Basque Government Department of Health (2015111117 to LA), the Basque Foundation for Innovation and Health Research (BIOEF), through the EiTB Maratoia grant BIO15/CA/016/BS to MLMC, the regional Government of Andalusia co-funded by CEC and FEDER funds (Proyectos de Excelencia P12-CTS-2232) and Fundación Domingo Martínez (to AP). LA is supported by the Ramon y Cajal program (RYC-2013-13666). DB, MMR and TMM are recipients of MCIU FPI fellowships. ACG and AP are recipients of fellowships form the Basque Government. APC is a recipient of a fellowship from the University of the Basque Country. We thank the MCIU for the Severo Ochoa Excellence accreditation (SEV-2016-0644), the Basque Department of Industry, Tourism and Trade (Etortek and Elkartek programs), the Innovation Technology Department of the Bizkaia Province and the CIBERehd network. DB and JA are supported by a grant from the Jesús de Gangoiti Barrera Foundation.

Cystathionine β-synthase (CBS), the pivotal enzyme of the reverse transsulfuration pathway, catalyzes the pyridoxal-5’-phosphate-dependent condensation of serine with homocysteine to form cystathionine. Additionally, CBS performs alternative reactions that use homocysteine and cysteine as substrates leading to the endogenous biosynthesis of hydrogen sulfide (H2S), an important signal transducer in many physiological and pathological processes. Toxoplasma gondii, the causative agent of toxoplasmosis, encodes a functional CBS (TgCBS) that contrary to human CBS, is not allosterically regulated by S-adenosylmethionine and can use both, Ser and O-acetylserine (OAS) as substrates. TgCBS is also strongly implicated in the production of H2S, and thus involved in redox homeostasis of the parasite. Here, we report its crystal structure, the first CBS from a protozoan described so far. Our data reveals a basal-like fold that unexpectedly differs from the active conformations found in other organisms, but structurally similar to the pathogenic activated mutant D444N of the human enzyme.

Background & Aims: Polycystic liver diseases (PLDs) are genetic disorders characterized by progressive development of multiple fluid-filled biliary cysts. Most PLD-causative genes participate in protein biogenesis and/or transport. Post-translational modifications (PTMs) are implicated in protein stability, localization and activity, contributing to human pathobiology; however, their role in PLD is unknown. Herein, we aimed to unveil the role of protein SUMOylation in PLD and its potential therapeutic targeting. Methods: Levels and functional effects of SUMOylation, along with response to S-adenosylmethionine (SAMe, inhibitor of the SUMOylation enzyme UBC9) and/or short-hairpin RNAs (shRNAs) against UBE2I (UBC9), were evaluated in vitro, in vivo and/or in patients with PLD. SUMOylated proteins were determined by immunoprecipitation and proteomic analyses by mass spectrometry. Results: Most SUMOylation-related genes were found overexpressed (mRNA) in polycystic human and rat liver tissue, as well as in cystic cholangiocytes in culture compared to controls. Increased SUMOylated protein levels were also observed in cystic human cholangiocytes in culture, which decreased after SAMe administration. Chronic treatment of polycystic (PCK: Pkdhl-mut) rats with SAMe halted hepatic cystogenesis and fibrosis, and reduced liver/body weight ratio and liver volume. In vitro, both SAMe and shRNA-mediated UBE2I knockdown increased apoptosis and reduced cell proliferation of cystic cholangiocytes. High-throughput proteomic analysis of SUM01-immunoprecipitated proteins in cystic cholangiocytes identified candidates involved in protein biogenesis, ciliogenesis and proteasome degradation. Accordingly, SAMe hampered proteasome hyperactivity in cystic cholangiocytes, leading to activation of the unfolded protein response and stress-related apoptosis. Conclusions: Cystic cholangiocytes exhibit increased SUMOylation of proteins involved in cell survival and proliferation, thus promoting hepatic cystogenesis. Inhibition of protein SUMOylation with SAMe halts PLD, representing a novel therapeutic strategy., Lay summary: Protein SUMOylation is a dynamic post-translational event implicated in numerous cellular processes. This study revealed dysregulated protein SUMOylation in polycystic liver disease, which promotes hepatic cystogenesis. Administration of S-adenosylmethionine (SAMe), a natural UBC9-dependent SUMOylation inhibitor, halted polycystic liver disease in experimental models, thus representing a potential therapeutic agent for patients., Graphical Abstract

Liver fibrosis is the excessive accumulation of extracellular matrix proteins that occurs in chronic liver disease. Ubiquitination is a post-translational modification that is crucial for a plethora of physiological processes. Even though the ubiquitin system has been implicated in several human diseases, the role of ubiquitination in liver fibrosis remains poorly understood. Here, multi-omics approaches were used to address this. Untargeted metabolomics showed that carbon tetrachloride (CCl4)-induced liver fibrosis promotes changes in the hepatic metabolome, specifically in glycerophospholipids and sphingolipids. Gene ontology analysis of public deposited gene array-based data and validation in our mouse model showed that the biological process &ldquo, protein polyubiquitination&rdquo, is enriched after CCl4-induced liver fibrosis. Finally, by using transgenic mice expressing biotinylated ubiquitin (bioUb mice), the ubiquitinated proteome was isolated and characterized by mass spectrometry in order to unravel the hepatic ubiquitinated proteome fingerprint in CCl4-induced liver fibrosis. Under these conditions, ubiquitination appears to be involved in the regulation of cell death and survival, cell function, lipid metabolism, and DNA repair. Finally, ubiquitination of proliferating cell nuclear antigen (PCNA) is induced during CCl4-induced liver fibrosis and associated with the DNA damage response (DDR). Overall, hepatic ubiquitome profiling can highlight new therapeutic targets for the clinical management of liver fibrosis.

© 2020 by the authors., Prostate cancer is the most frequent malignancy in European men and the second worldwide. One of the major oncogenic events in this disease includes amplification of the transcription factor cMYC. Amplification of this oncogene in chromosome 8q24 occurs concomitantly with the copy number increase in a subset of neighboring genes and regulatory elements, but their contribution to disease pathogenesis is poorly understood. Here we show that TRIB1 is among the most robustly upregulated coding genes within the 8q24 amplicon in prostate cancer. Moreover, we demonstrate that TRIB1 amplification and overexpression are frequent in this tumor type. Importantly, we find that, parallel to its amplification, TRIB1 transcription is controlled by cMYC. Mouse modeling and functional analysis revealed that aberrant TRIB1 expression is causal to prostate cancer pathogenesis. In sum, we provide unprecedented evidence for the regulation and function of TRIB1 in prostate cancer., We are grateful to the Carracedo lab for valuable input, to Ana M. Aransay and F. Elortza for technical advice. P.S. was funded by the European Training Networks Project (H2020-MSCA-ITN-308 2016 721532). V.T. is funded by Fundación Vasca de Innovación e Investigación Sanitarias, BIOEF (BIO15/CA/052), the AECC J.P. Bizkaia, the Basque Department of Health (2016111109) and the MICINN RTI2018-097267-B-I00. A. Macchia was funded by a FPI predoctoral fellowship from MICINN (PRE2018-083607). EB is funded by the MICINN (BFU2016-76872-R (FEDER/EU), PID2019-108112RB-I00, Severo Ochoa Excellence Accreditation SEV-2016-0644 and Excellence Networks SAF2017-90794-REDT). The work of A. Carracedo is supported by the Basque Department of Industry, Tourism and Trade (Elkartek), the department of education (IKERTALDE IT1106-16) and health (RIS3), the BBVA foundation and the MICINN (SAF2016-79381-R (FEDER/EU; PID2019-108787RB-I00) Severo Ochoa Excellence Accreditation SEV-2016-0644 and Excellence Networks SAF2016-81975-REDT and RED2018-102769-T), European Training Networks Project (H2020-MSCA-ITN-308 2016 721532), the AECC (IDEAS175CARR, GCTRA18006CARR), La Caixa Foundation (ID 100010434), under the agreement LCF/PR/HR17/ and the European Research Council (Starting Grant 336343, Consolidator Grant 819242). CIBERONC was co-funded with FEDER funds and funded by ISCIII.

Background and purpose The expression of the human organic cation transporter-1 (hOCT1, gene SLC22A1) is reduced in hepatocellular carcinoma (HCC). The molecular bases of this reduction and its relationship with the poor response of HCC to sorafenib were investigated. Experimental approach HCC transcriptomes from 366 samples available at TCGA were analysed. Alternative splicing was determined by RT-PCR. The role of miRNAs in SLC22A1 downregulation was investigated. Expression of Oct1 was measured in rodent HCC models (spontaneously generated in Fxr-/- mice and chemically-induced in rats). hOCT1 was overexpressed in human hepatoma cells (HuH7 and HepG2). Sorafenib and regorafenib uptake was determined by HPLC-MS/MS. Key results hOCT1 overexpression enhanced sorafenib, but not regorafenib, quinine-inhibitable uptake by hepatoma cells. In rodent HCC, Oct1 was downregulated, which was accompanied by impaired sorafenib uptake. In mice with s.c.-implanted HCC, sorafenib inhibited the growth of hOCT1 overexpressing tumours. In human HCC, hOCT1 expression was inversely correlated with SLC22A1 promoter methylation, whereas demethylation with decitabine enhanced hOCT1 expression in hepatoma cells. Increased proportion of aberrant hOCT1 mRNA variants was found in HCC samples. In silico analysis identified six miRNAs as candidates to target hOCT1 mRNA. When overexpressed in HepG2 cells a significant hOCT1 mRNA decay was induced by hsa-miR-330 and hsa-miR-1468. Analysis of 39 paired tumour/adjacent samples from TCGA revealed that hsa-mir-330 was consistently upregulated in HCC. Conclusion and implications Impaired hOCT1 expression/function in HCC, in part due to epigenetic modifications, plays an important role in the poor pharmacological response of this cancer to sorafenib.

Acute liver failure (ALF) is a life-threatening syndrome characterised by rapid hepatocellular necrosis due to various types of insults including drugs, autoimmune disorders or viral infections, and thus represents a disease with high mortality and elevated societal costs. At present, most ALF treatment strategies are rather aimed at simply preventing complications and decelerating disease progression. Unfortunately, the only curative treatment for ALF at present is liver transplantation, an option which is limited due to financial constraints, shortage of donor livers and immunosuppression-related complications.1 Therefore, novel therapeutic avenues for patients with ALF are urgently needed. Normally, mature hepatocytes can orchestrate liver regeneration on loss of liver mass. When severe liver insult occurs, however, hepatocytes are unable to differentiate and hepatic progenitor cells (HPCs) are activated. HPCs, embryonic stem cells (ES) and induced pluripotent stem cells (iPS) have been considered a potential source for cell replacement in the injured liver since they possess hepatic differentiation capacity.2 However, their clinical applicability remains still controversial. For long, it has been widely assumed that hepatocytes do not contribute directly to the progenitor or stem cell compartment. Recently, Chen and colleagues2 reported the dedifferentiation of progenitor cells from isolated mature hepatocytes, refuting the current dogma. Yet to be explored was the identification of molecular cascades that specifically dedifferentiate mature hepatocytes and activate a ‘fetal programme’. The Hippo/Yes-associated protein (YAP)-signalling pathway plays an essential role by determining cellular fates in the mammalian liver. Hippo signalling controls the phosphorylation of the transcriptional co-activator YAP whose constitutive activation in …

Salp15, a salivary protein of Ixodes ticks, inhibits the activation of naïve CD4 T cells. Treatment with Salp15 results in the inhibition of early signaling events and the production of the autocrine growth factor, interleukin-2. The fate of the CD4 T cells activated in the presence of Salp15 or its long-term effects are, however, unknown. We now show that Salp15 binding to CD4 is persistent and induces a long-lasting immunomodulatory effect. The activity of Salp15 results in sustained diminished cross-antigenic antibody production even after interruption of the treatment with the protein. Transcriptionally, the salivary protein provokes an acute effect that includes known activation markers, such as Il2 or Cd44, and that fades over time. The long-term effects exerted by Salp15 do not involve the induction of either anergy traits nor increased populations of regulatory T cells. Similarly, the treatment with Salp15 does not result in B cell anergy or the generation of myeloid suppressor cells. However, Salp15 induces the increased expression of the ectoenzyme, CD73, in regulatory T cells and increased production of adenosine. Our study provides a profound characterization of the immunomodulatory activity of Salp15 and suggests that its long-term effects are due to the specific regulation of CD73. Introduction, Supported by grants from the Department of Education of the Basque Government (PI2013-49 to JA and PI2012-42 to RB). JA is funded by the European Union (Grant Agreement number 602272). AMA and JLL’s work was supported by the Basque Department of Industry, Tourism and Trade (Etortek and Elkartek Programs), the Innovation Technology Department of Bizkaia and the CIBERehd Network. The work of AC is supported by a Ramón y Cajal award, the Basque Department of Industry, Tourism and Trade (Etortek), ISCIII (PI13/00031), FERO VIII Fellowship, the BBVA foundation, MINECO (SAF2016-79381-R) and the European Research Council Starting Grant (336343). CIBERonc was co-funded with FEDER funds. AC-M was funded by a Juan de la Cierva program award and the European Union MSCA program (CIG 660191). RB was funded by MINECO grants BFU2011-25986 and BFU2014-52282-P and the Consolider Program (BFU2014-57703-REDC). FJB was funded by a MINECO grant (CTQ2014-56966-R). D.B. is funded by a MINECO FPI fellowship. We thank the MINECO for the Severo Ochoa Excellence accreditation (SEV-2016-0644).

Osteopontin (OPN), a senescence‐associated secretory phenotype factor, is increased in patients with nonalcoholic fatty liver disease (NAFLD). Cellular senescence has been associated with age‐dependent hepatosteatosis. Thus, we investigated the role of OPN in the age‐related hepatosteatosis. For this, human serum samples, animal models of aging, and cell lines in which senescence was induced were used. Metabolic fluxes, lipid, and protein concentration were determined. Among individuals with a normal liver, we observed a positive correlation between serum OPN levels and increasing age. This correlation with age, however, was absent in patients with NAFLD. In wild‐type (WT) mice, serum and liver OPN were increased at 10 months old (m) along with liver p53 levels and remained elevated at 20m. Markers of liver senescence increased in association with synthesis and concentration of triglycerides (TG) in 10m OPN‐deficient (KO) hepatocytes when compared to WT hepatocytes. These changes in senescence and lipid metabolism in 10m OPN‐KO mice liver were associated with the decrease of 78 kDa glucose‐regulated protein (GRP78), induction of ER stress, and the increase in fatty acid synthase and CD36 levels. OPN deficiency in senescent cells also diminished GRP78, the accumulation of intracellular TG, and the increase in CD36 levels. In 20m mice, OPN loss led to increased liver fibrosis. Finally, we showed that OPN expression in vitro and in vivo was regulated by p53. In conclusion, OPN deficiency leads to earlier cellular senescence, ER stress, and TG accumulation during aging. The p53‐OPN axis is required to inhibit the onset of age‐related hepatosteatosis., OPN is a protective factor required to preserve liver health during aging. As OPN‐deficient mice become older, increased levels of senescence, ER stress, hepatosteatosis, DNA damage, fibrosis, and inflammation appear.

Adaptation to hypoxia is a common feature in solid tumors orchestrated by oxygen-dependent and independent upregulation of the hypoxia-inducible factor-1&alpha, (HIF-1&alpha, ). We unveiled that G protein-coupled receptor kinase (GRK2), known to be overexpressed in certain tumors, fosters this hypoxic pathway via phosphorylation of the mRNA-binding protein HuR, a central HIF-1&alpha, modulator. GRK2-mediated HuR phosphorylation increases the total levels and cytoplasmic shuttling of HuR in response to hypoxia, and GRK2-phosphodefective HuR mutants show defective cytosolic accumulation and lower binding to HIF-1&alpha, mRNA in hypoxic Hela cells. Interestingly, enhanced GRK2 and HuR expression correlate in luminal breast cancer patients. GRK2 also promotes the HuR/HIF-1&alpha, axis and VEGF-C accumulation in normoxic MCF7 breast luminal cancer cells and is required for the induction of HuR/HIF1-&alpha, in response to adrenergic stress. Our results point to a relevant role of the GRK2/HuR/HIF-1&alpha, module in the adaptation of malignant cells to tumor microenvironment-related stresses.

Cancer cells can develop a strong addiction to discrete molecular regulators, which control the aberrant gene expression programs that drive and maintain the cancer phenotype. Here, we report the identification of the RNA-binding protein HuR/ELAVL1 as a central oncogenic driver for malignant peripheral nerve sheath tumors (MPNSTs), which are highly aggressive sarcomas that originate from cells of the Schwann cell lineage. HuR was found to be highly elevated and bound to a multitude of cancer-associated transcripts in human MPNST samples. Accordingly, genetic and pharmacological inhibition of HuR had potent cytostatic and cytotoxic effects on tumor growth, and strongly suppressed metastatic capacity in vivo. Importantly, we linked the profound tumorigenic function of HuR to its ability to simultaneously regulate multiple essential oncogenic pathways in MPNST cells, including the Wnt/beta-catenin, YAP/TAZ, RB/E2F, and BET pathways, which converge on key transcriptional networks. Given the exceptional dependency of MPNST cells on HuR for survival, proliferation, and dissemination, we propose that HuR represents a promising therapeutic target for MPNST treatment. This work was funded by grants to AW from the Spanish Association Against Cancer (AECC; JP Vizcaya); Spanish Ministry of Science, Innovation and Universities (MCIU)/Agencia Estatal de Investigacion (AEI)/European Regional Development Fund (FEDER), European Union (EU) (Subprograma Ramon y Cajal RYC2010-06901; Proyectos Retos Investigacion RTI2018-097503-B-I00, SAF2015-65360-R; Proyectos Explora Ciencia SAF2015-72416-EXP; Proyectos Europa Excelencia SAF2015-62588-ERC); the BBVA Foundation; Basque Department of Industry, Tourism and Trade (Elkartek) and Education (PI2013-46); Fundacion Vasca de Innovacion e Investigacion Sanitarias EiTB Maratoia (BIO13/CI/015); the Neurofibromatosis Therapeutic Acceleration Program; and the European Research Council (consolidator grant under the EU's Horizon 2020 research and innovation programme; grant agreement 865157). MVR is grateful for the support of a 2017 Leonardo Grant for Researchers and Cultural Creators (BBVA Foundation), Accion Estrategica Ciber Emergentes 2018 (Ciberehd-ISCIII), and Gilead Sciences International Research Scholars Program in Liver Disease. The work of AC is supported by the Basque Department of Industry, Tourism and Trade (Elkartek) and Education (IKERTALDE IT1106-16); the BBVA Foundation; the MCIU/AEI (SAF2016-79381-R [FEDER/EU]; Severo Ochoa Excellence Accreditation SEV-2016-0644; Excellence Networks SAF20168-1975-REDT); the European Training Networks Project (H2020-MSCA-ITN-308 2016 721532); the AECC (IDEAS175CARR, GCTRA18006CARR); La Caixa Foundation (HR17-00094); and the European Research Council (Starting Grant 336343, PoC 754627). MG was supported by the Intramural Research Program of the National Institute on Aging, NIH. MPI is grateful for the support of the Basque Government of Education fellowship. MTC is grateful for the support of "Ayudas para contratos predoctorales para la formacion de doctores" (MCIU/AEI/FEDER, EU). COH acknowledges funding from Brain Tumour Research. RB acknowledges MCIU/AEI/FEDER, EU (BFU2014-52282-P and BFU2017-84653-P). ES and CL are supported by the Carlos III National Health Institute funded by FEDER funds - a way to build Europe (CIBERONC) and the Government of Catalonia (2017SGR496). MLM-C acknowledges support from MCIU/AEI/FEDER, EU (SAF2017-87301-R); Asociacion Espanola Contra El Cancer (AECC); AECC Canceres Raros; BBVA Biomedicina (UMBRELLA); and La CAIXA Foundation (LCF/PR/HP17/52190004). AP was supported by Associazione Italiana Ricerca sul Cancro (AIRC; IG 2018 Id.21548). CIBERehd is funded by the Instituto de Salud Carlos III. We thank MCIU for the Severo Ochoa Excellence Accreditation (SEV-2016-0644).

Liver fibrosis is characterized by the excessive deposition of extracellular matrix proteins including collagen that occurs in most types of chronic liver disease. Even though our knowledge of the cellular and molecular mechanisms of liver fibrosis has deeply improved in the last years, therapeutic approaches for liver fibrosis remain limited. Profiling and characterization of the post-translational modifications (PTMs) of proteins, and more specifically NEDDylation and SUMOylation ubiquitin-like (Ubls) modifications, can provide a better understanding of the liver fibrosis pathology as well as novel and more effective therapeutic approaches. On this basis, in the last years, several studies have described how changes in the intermediates of the Ubl cascades are altered during liver fibrosis and how specific targeting of particular enzymes mediating these ubiquitin-like modifications can improve liver fibrosis, mainly in in vitro models of hepatic stellate cells, the main fibrogenic cell type, and in pre-clinical mouse models of liver fibrosis. The development of novel inhibitors of the Ubl modifications as well as novel strategies to assess the modified proteome can provide new insights into the overall role of Ubl modifications in liver fibrosis.

International audience; Post-translational modification is a key mechanism regulating protein homeostasis and function in eukaryotic cells. Among all ubiquitin-like proteins in liver cancer, the modification by SUMO (Small Ubiquitin MOdifier) has been given the most attention. Isolation of endogenous SUMOylated proteins in vivo is challenging due to the presence of active SUMO-specific proteases. Initial studies of SUMOylation in vivo were based on the molecular detection of specific SUMOylated proteins (e.g., by western blot). However, in many cases, antibodies, generally made with non-modified recombinant protein, did not immunoprecipitate SUMOylated forms of the protein of interest. Nickel chromatography has been the other approach to study SUMOylation by capturing histidine-tagged versions of SUMO molecules. This approach is mainly used in cells stably expressing or transiently transfected with His-SUMO molecules. To overcome these limitations, SUMO-binding entities (SUBEs) were developed to isolate endogenous SUMOylated proteins. Herein, we describe all the steps required for the enrichment, isolation, and identification of SUMOylated substrates from human hepatoma cells and hepatic tissues from a liver cancer mouse model by using SUBEs. Firstly, we describe methods involved in the preparation and lysis of the human hepatoma cells and liver tumor tissue samples. Then, a thorough explanation of the preparation of SUBEs and controls is detailed along with the protocol for the protein pull-down assays. Finally, some examples are provided regarding the options available for the identification and characterization of the SUMOylated proteome, namely the use of western-blot analysis for the detection of a specific SUMOylated substrate from liver tumors or the use of proteomics by mass spectrometry for high-throughput characterization of the SUMOylated proteome and interactome in hepatoma cells.

Objective Non-alcoholic fatty liver disease (NAFLD) is a complex pathology in which several dysfunctions, including alterations in metabolic pathways, mitochondrial functionality and unbalanced lipid import/export, lead to lipid accumulation and progression to inflammation and fibrosis. The enzyme glycine N-methyltransferase (GNMT), the most important enzyme implicated in S-adenosylmethionine catabolism in the liver, is downregulated during NAFLD progression. We have studied the mechanism involved in GNMT downregulation by its repressor microRNA miR-873-5p and the metabolic pathways affected in NAFLD as well as the benefit of recovery GNMT expression. Methods miR-873-5p and GNMT expression were evaluated in liver biopsies of NAFLD/NASH patients. Different in vitro and in vivo NAFLD murine models were used to assess miR-873-5p/GNMT involvement in fatty liver progression through targeting of the miR-873-5p as NAFLD therapy. Results We describe a new function of GNMT as an essential regulator of Complex II activity in the electron transport chain in the mitochondria. In NAFLD, GNMT expression is controlled by miR-873-5p in the hepatocytes, leading to disruptions in mitochondrial functionality in a preclinical murine non-alcoholic steatohepatitis (NASH) model. Upregulation of miR-873-5p is shown in the liver of NAFLD/NASH patients, correlating with hepatic GNMT depletion. Importantly, NASH therapies based on anti-miR-873-5p resolve lipid accumulation, inflammation and fibrosis by enhancing fatty acid β-oxidation in the mitochondria. Therefore, miR-873-5p inhibitor emerges as a potential tool for NASH treatment. Conclusion GNMT participates in the regulation of metabolic pathways and mitochondrial functionality through the regulation of Complex II activity in the electron transport chain. In NAFLD, GNMT is repressed by miR-873-5p and its targeting arises as a valuable therapeutic option for treatment., Graphical abstract Image 1, Highlights • The microRNA miR-873-5p is upregulated in human and murine NAFLD/NASH livers. • miR-873-5p upregulation downregulates GNMT in the liver. • miR-873-5p inhibition reduces liver steatosis, inflammation and fibrosis in in vivo NAFLD mouse models. • GNMT is a hepatic metabolic hub with mitochondria activity through the regulation of Complex II of the ETC. • Mitochondrial GNMT deficiency compromises ETC functionality and metabolism.

Summary Ubiquitin and ubiquitin-like chains are finely balanced by conjugating and de-conjugating enzymes. Alterations in this balance trigger the response to stress conditions and are often observed in pathologies. How such changes are detected is not well understood. We identify the HSP70 chaperone as a sensor of changes in the balance between mono- and poly-NEDDylation. Upon DNA damage, the induction of the de-NEDDylating enzyme NEDP1 restricts the formation of NEDD8 chains, mainly through lysines K11/K48. This promotes APAF1 oligomerization and apoptosis induction, a step that requires the HSP70 ATPase activity. HSP70 binds to NEDD8, and, in vitro, the conversion of NEDD8 chains into mono-NEDD8 stimulates HSP70 ATPase activity. This effect is independent of NEDD8 conjugation onto substrates. The study indicates that the NEDD8 cycle is a regulatory module of HSP70 function. These findings may be important in tumorigenesis, as we find decreased NEDP1 levels in hepatocellular carcinoma with concomitant accumulation of NEDD8 conjugates., Graphical Abstract, Highlights • Restriction of NEDD8 chains by NEDP1 is required for DNA damage-induced apoptosis • The HSP70 chaperone is a sensor of the balance between mono- and NEDD8 chains • Mono-NEDD8 stimulates HSP70 activity, which allows the formation of the apoptosome • NEDP1 levels are downregulated in mouse hepatocellular carcinoma, The formation of ubiquitin and/or ubiquitin-like polymers is dynamically balanced by conjugating and de-conjugating enzymes. Bailly et al. report that the HSP70 chaperone is a sensor of the NEDD8 cycle. Conversion of NEDD8 chains into mono-NEDD8 by the de-NEDDylating enzyme NEDP1 upon DNA damage activates HSP70, which allows the formation of the apoptosome and apoptosis induction.

SummaryUbiquitin and ubiquitin-like chains are finely balanced by the action of conjugating and de-conjugating enzymes. Alterations in this balance trigger signalling events required for the response to stress conditions and are often observed in pathologies. How such changes are detected is not well-understood. We show that upon DNA damage the induction of the de-NEDDylating enzyme NEDP1 restricts the formation of poly-NEDD8 chains, mainly through lysines K11/K48. This promotes APAF1 oligomerisation and apoptosis induction, a step that requires the HSP70 ATPase activity. We found that HSP70 binds to NEDD8 and in vitro, mono-NEDD8 stimulates the ATPase activity of HSP70, counteracted upon poly-NEDDylation. This effect is independent of NEDD8 conjugation onto substrates. The studies identify the HSP70 chaperone as sensor of changes in the NEDD8 cycle, providing mechanistic insights for a cytoplasmic role of NEDD8 in the DNA damage induced apoptosis. They also indicate that the balance between mono- versus poly-NEDDylation is a regulatory module of HSP70 function. The above findings may be important in tumorigenesis, as we find that NEDP1 levels are downregulated in Hepatocellular Carcinoma with concomitant accumulation of NEDD8 conjugates.

Phosphatases of regenerating liver (PRLs), the most oncogenic of all protein-tyrosine phosphatases (PTPs), play a critical role in metastatic progression of cancers. Recent findings established a new paradigm by uncovering that their association with magnesium transporters of the cyclin M (CNNM) family causes a rise in intracellular magnesium levels that promote oncogenic transformation. Recently, however, essential roles for regulation of the circadian rhythm and reproduction of the CNNM family have been highlighted. Here, we describe the crystal structure of PRL-1 in complex with the Bateman module of CNNM2 (CNNM2BAT), which consists of two cystathionine β-synthase (CBS) domains (IPR000664) and represents an intracellular regulatory module of the transporter. The structure reveals a heterotetrameric association, consisting of a disc-like homodimer of CNNM2BAT bound to two independent PRL-1 molecules, each one located at opposite tips of the disc. The structure highlights the key role played by Asp-558 at the extended loop of the CBS2 motif of CNNM2 in maintaining the association between the two proteins and proves that the interaction between CNNM2 and PRL-1 occurs via the catalytic domain of the phosphatase. Our data shed new light on the structural basis underlying the interaction between PRL phosphatases and CNNM transporters and provides a hypothesis about the molecular mechanism by which PRL-1, upon binding to CNNM2, might increase the intracellular concentration of Mg2+ thereby contributing to tumor progression and metastasis. The availability of this structure sets the basis for the rational design of compounds modulating PRL-1 and CNNM2 activities.

Hepatic fibrosis is a global health problem currently without effective therapeutic approaches. Even though the ubiquitin-like posttranslational modification of neddylation, that conjugates Nedd8 (neural precursor cell expressed developmentally downregulated) to specific targets, is aberrant in many pathologies, its relevance in liver fibrosis (LF) remained unexplored. Our results show deregulated neddylation in clinical fibrosis and both in mouse bileductligation– and CCl4-induced fibrosis. Importantly, neddylation inhibition, by using the pharmacological inhibitor, MLN4924, reduced liver injury, apoptosis, inflammation, and fibrosis by targeting different hepatic cell types. On one hand, increased neddylation was associated with augmented caspase 3 activity in bile-acid–induced apoptosis in mouse hepatocytes whereas neddylation inhibition ameliorated apoptosis through reduction of expression of the Cxcl1 and Ccl2 chemokines. On the other hand, chemokine receptors and cytokines, usually induced in activated macrophages, were reduced after neddylation inhibition in mouse Kupffer cells. Under these circumstances, decreased hepatocyte cell death and inflammation after neddylation inhibition could partly account for reduction of hepatic stellate cell (HSC) activation. We provide evidence that augmented neddylation characterizes activated HSCs, suggesting that neddylation inhibition could be important for resolving LF by directly targeting these fibrogenic cells. Indeed, neddylation inhibition in activated HSCs induces apoptosis in a process partly mediated by accumulation of c-Jun, whose cullin-mediated degradation is impaired under these circumstances. Conclusion: Neddylation inhibition reduces fibrosis, suggesting neddylation as a potential and attractive therapeutic target in liver fibrosis. (Hepatology 2017;65:694-709).

Cholestasis comprises aetiologically heterogeneous conditions characterized by accumulation of bile acids in the liver that actively contribute to liver damage. Sirtuin 1 (SIRT1) regulates liver regeneration and bile acid metabolism by modulating farnesoid X receptor (FXR); we here investigate its role in cholestatic liver disease. We determined SIRT1 expression in livers from patients with cholestatic disease, in two experimental models of cholestasis, as well as in human and murine liver cells in response to bile acid loading. SIRT1-overexpressing (SIRToe) and hepatocyte-specific SIRT1-KO (knockout) mice (SIRThep-/-) were subjected to bile duct ligation (BDL) and were fed with a 0.1% DDC (3,5-diethoxycarbonyl-1,4-dihydrocollidine) diet to determine the biological relevance of SIRT1 during cholestasis. The effect of NorUDCA (24-norursodeoxycholic acid) was tested in BDL/SIRToe mice. We found that SIRT1 was highly expressed in livers from cholestatic patients, mice after BDL, and Mdr2 knockout mice (Mdr2(-/-)) animals. The detrimental effects of SIRT1 during cholestasis were validated in vivo and in vitro. SIRToe mice showed exacerbated parenchymal injury whereas SIRThep-/- mice evidenced a moderate improvement after BDL and 0.1% DDC feeding. Likewise, hepatocytes isolated from SIRToe mice showed increased apoptosis in response to bile acids, whereas a significant reduction was observed in SIRThep-/- hepatocytes. Importantly, the decrease, but not complete inhibition, of SIRT1 exerted by norUDCA treatment correlated with pronounced improvement in liver parenchyma in BDL/SIRToe mice. Interestingly, both SIRT1 overexpression and hepatocyte-specific SIRT1 depletion correlated with inhibition of FXR, whereas modulation of SIRT1 by NorUDCA associated with restored FXR signaling. Conclusion: SIRT1 expression is increased during human and murine cholestasis. Fine-tuning expression of SIRT1 is essential to protect the liver from cholestatic liver damage. Supported by the Biotechnology and Biological Sciences Research Council (BBSRC) by the BBSRC Institute Strategic Programme Gut Health and Food Safety and Gut Microbes and Health BBS/E/F/00044509 (to N.B.), the NRP Science Links Seed Corn Fund grant (to N.B., S.R.), Biotechnology and Biological Sciences Research Council (BBSRC) Doctoral Training Partnership programme (to N.B., A.T.), and Instituto de Salud Carlos III; FIS, PS12/00402 (to N.B. and M.V.R.). N.B. was funded by the BBSRC Institute Strategic Programme Gut Health and Food Safety BB/J004529/1, the Program Ramon y Cajal (Ministry of Economy and Competitiveness, Spain) and Ikerbaske foundation (Basque government, Spain). FIS PI12/00380, FIS PI15/01132, and Miguel Servet Program CON14/00129 cofinanced by "Fondo Europeo de Desarrollo Regional" (FEDER; to J.M.B.). Gobierno Vasco-Departamento de Salud 2013111114 (to M.L.M.-C.), MINECO: SAF2014-54658-R, EITB Maratoia BIO15/CA/014 (to M.L.M.C.) Asociacion Espanola contra el Cancer. Ciberehd is funded by the Instituto de Salud Carlos III. Work produced with the support of a 2017 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation (to M.V.R.). M.E. and M.G. were supported by the Camara de Comercio de Navarra.

The cyclin and cystathionine β-synthase (CBS) domain magnesium transport mediators, CNNMs, are key players in maintaining the homeostasis of magnesium in different organs. The human family includes four members, whose impaired activity causes diseases such as Jalili Syndrome or Familial Hypomagnesemia, but is also linked to neuropathologic disorders, altered blood pressure, and infertility. Recent findings demonstrated that CNNMs are associated with the highly oncogenic phosphatases of the regenerating liver to promote tumor growth and metastasis, which has attracted renewed focus on their potential exploitation as targets for cancer treatment. However, the exact function of CNNMs remains unclear and is subject to debate, proposed as either direct transporters, sensors, or homeostatic factors. This review gathers the current structural knowledge on the CNNM family, highlighting similarities and differences with the closely related structural partners such as the bacterial Mg2+/Co2+ efflux protein CorC and the Mg2+ channel MgtE.

Background Even though liver kinase B1 (LKB1) is usually described as a tumor suppressor in a wide variety of tissues, it has been shown that LKB1 aberrant expression is associated with bad prognosis in Hepatocellular Carcinoma (HCC). Methods Herein we have overexpressed LKB1 in human hepatoma cells and by using histidine pull-down assay we have investigated the role of the hypoxia-related post-translational modification of Small Ubiquitin-related Modifier (SUMO)ylation in the regulation of LKB1 oncogenic role. Molecular modelling between LKB1 and its interactors, involved in regulation of LKB1 nucleocytoplasmic shuttling and LKB1 activity, was performed. Finally, high affinity SUMO binding entities-based technology were used to validate our findings in a pre-clinical mouse model and in clinical HCC. Findings We found that in human hepatoma cells under hypoxic stress, LKB1 overexpression increases cell viability and aggressiveness in association with changes in LKB1 cellular localization. Moreover, by using site-directed mutagenesis, we have shown that LKB1 is SUMOylated by SUMO-2 at Lys178 hampering LKB1 nucleocytoplasmic shuttling and fueling hepatoma cell growth. Molecular modelling of SUMO modified LKB1 further confirmed steric impedance between SUMOylated LKB1 and the STe20-Related ADaptor cofactor (STRADα), involved in LKB1 export from the nucleus. Finally, we provide evidence that endogenous LKB1 is modified by SUMO in pre-clinical mouse models of HCC and clinical HCC, where LKB1 SUMOylation is higher in fast growing tumors. Interpretation Overall, SUMO-2 modification of LKB1 at Lys178 mediates LKB1 cellular localization and its oncogenic role in liver cancer. Fund This work was supported by grants from NIH (US Department of Health and Human services)-R01AR001576-11A1 (J.M.M and M.L.M-C.), Gobierno Vasco-Departamento de Salud 2013111114 (to M.L.M.-C), ELKARTEK 2016, Departamento de Industria del Gobierno Vasco (to M.L.M.-C), MINECO: SAF2017–87301-R and SAF2014–52097-R integrado en el Plan Estatal de Investigación Cientifica y Técnica y Innovación 2013–2016 cofinanciado con Fondos FEDER (to M.L.M.-C and J.M.M., respectively), BFU2015–71017/BMC MINECO/FEDER, EU (to A.D.Q. and I.D.M.), BIOEF (Basque Foundation for Innovation and Health Research): EITB Maratoia BIO15/CA/014; Instituto de Salud Carlos III:PIE14/00031, integrado en el Plan Estatal de Investigación Cientifica y Técnica y Innovacion 2013–2016 cofinanciado con Fondos FEDER (to M.L.M.-C and J.M.M), Asociación Española contra el Cáncer (T.C.D, P·F-T and M.L.M-C), Daniel Alagille award from EASL (to T.C.D), Fundación Científica de la Asociación Española Contra el Cancer (AECC Scientific Foundation) Rare Tumor Calls 2017 (to M.L.M and M.A), La Caixa Foundation Program (to M.L.M), Programma di Ricerca Regione-Università 2007–2009 and 2011–2012, Regione Emilia-Romagna (to E.V.), Ramón Areces Foundation and the Andalusian Government (BIO-198) (A.D.Q. and I.D.M.), ayudas para apoyar grupos de investigación del sistema Universitario Vasco IT971–16 (P.A.), MINECO:SAF2015–64352-R (P.A.), Institut National du Cancer, FRANCE, INCa grant PLBIO16–251 (M.S.R.), MINECO - BFU2016–76872-R to (E.B.). Work produced with the support of a 2017 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation (M.V-R). Finally, Ciberehd_ISCIII_MINECO is funded by the Instituto de Salud Carlos III. We thank MINECO for the Severo Ochoa Excellence Accreditation to CIC bioGUNE (SEV-2016-0644). Funding sources had no involvement in study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication., Highlights • Overexpression of LKB1 in human hepatoma cells during hypoxic stress induces deregulated cell growth and survival. • SUMO-2 modifications of LKB1 at Lys178 occur in human hepatoma cells hampering its nucleocytoplasmic shuttling. • LKB1 SUMOylation is augmented in pre-clinical mouse models and clinical HCC, being a hallmark of more aggressive HCC tumors.

Background: SerpinB3 (SB3) is a hypoxia and hypoxia-inducible factor (HIF)-2&alpha, dependent cysteine-protease inhibitor up-regulated in hepatocellular carcinoma (HCC), released by cancer cells and able to stimulate proliferation and epithelial-to-mesenchymal-transition. Methods: In the study we employed transgenic and knock out SerpinB3 mice, liver cancer cell line, human HCC specimens, and mice receiving diethyl-nitrosamine (DEN) administration plus choline-deficient L-amino acid refined (CDAA) diet (DEN/CDAA protocol). Results: We provide detailed and mechanistic evidence that SB3 can act as a paracrine mediator able to affect the behavior of surrounding cells by differentially up-regulating, in normoxic conditions, HIF-1&alpha, and HIF-2&alpha, SB3 acts by (i) up-regulating HIF-1&alpha, transcription, facilitating cell survival in a harsh microenvironment and promoting angiogenesis, (ii) increasing HIF-2&alpha, stabilization via direct/selective NEDDylation, promoting proliferation of liver cancer cells, and favoring HCC progression. Moreover (iii) the highest levels of NEDD8-E1 activating enzyme (NAE1) mRNA were detected in a subclass of HCC patients expressing the highest levels of HIF-2&alpha, transcripts, (iv) mice undergoing DEN/CDAA carcinogenic protocol showed a positive correlation between SB3 and HIF-2&alpha, transcripts with the highest levels of NAE1 mRNA detected in nodules expressing the highest levels of HIF-2&alpha, transcripts. Conclusions: These data outline either HIF-2&alpha, and NEDDylation as two novel putative therapeutic targets to interfere with the procarcinogenic role of SerpinB3 in the development of HCC.

Insulin resistance (IR) and obesity are important risk factors for non-alcoholic fatty liver disease (NAFLD). G protein-coupled receptor kinase 2 (GRK2) is involved in the development of IR and obesity in vivo. However, its possible contribution to NAFLD and/or non-alcoholic steatohepatitis (NASH) independently of its role on IR or fat mass accretion has not been explored. Here, we used wild-type (WT) or GRK2 hemizygous (GRK2±) mice fed a high-fat diet (HFD) or a methionine and choline-deficient diet (MCD) as a model of NASH independent of adiposity and IR. GRK2± mice were protected from HFD-induced NAFLD. Moreover, MCD feeding caused an increased in triglyceride content and liver-to-body weight ratio in WT mice, features that were attenuated in GRK2± mice. According to their NAFLD activity score, MCD-fed GRK2± mice were diagnosed with simple steatosis and not overt NASH. They also showed reduced expression of lipogenic and lipid-uptake markers and less signs of inflammation in the liver. GRK2± mice preserved hepatic protective mechanisms as enhanced autophagy and mitochondrial fusion and biogenesis, together with reduced endoplasmic reticulum stress. GRK2 protein was increased in MCD-fed WT but not in GRK2± mice, and enhanced GRK2 expression potentiated palmitic acid-triggered lipid accumulation in human hepatocytes directly relating GRK2 levels to steatosis. GRK2 protein and mRNA levels were increased in human liver biopsies from simple steatosis or NASH patients in two different human cohorts. Our results describe a functional relationship between GRK2 levels and hepatic lipid accumulation and implicate GRK2 in the establishment and/or development of NASH., Ministerio de Economia y Competitividad (MINECO/FEDER), Spain (grants SAF2014-55511-R and SAF2017-84125-R to F.M and C. M., grant SAF2015-65267-R to A.M.V., grant SAF2016-76028R to L.F. and SAF2017-87301-R to M.L.M.-C); Comunidad de Madrid-B2017/BMD-3671-INFLAMUNE to F.M.; Gobierno Vasco-Departamento de Salud 2013111114 and EITB Maratoia BIO15/CA/014 (to M.L.M.C); European Foundation for the Study of Diabetes (EFSD) Novo Nordisk Partnership for Diabetes Research in Europe Grant (to F.M.); Asociacion Espanola contra el Cancer (M.L.M-C) and Fundacion Ramon Areces (to C.M.). Instituto de Salud Carlos III (with European FEDER contribution) funds CIBERCV (grant CB16/11/00278 to F.M), CIBERDEM and CIBERehd

Under a Creative Commons license.-- et al., Proliferation is an important part of cancer development and progression. This is manifest by altered expression and/or activity of cell cycle related proteins. Constitutive activation of many signal transduction pathways also stimulates cell growth. Early steps in tumor development are associated with a fibrogenic response and the development of a hypoxic environment which favors the survival and proliferation of cancer stem cells. Part of the survival strategy of cancer stem cells may manifested by alterations in cell metabolism. Once tumors appear, growth and metastasis may be supported by overproduction of appropriate hormones (in hormonally dependent cancers), by promoting angiogenesis, by undergoing epithelial to mesenchymal transition, by triggering autophagy, and by taking cues from surrounding stromal cells. A number of natural compounds (e.g., curcumin, resveratrol, indole-3-carbinol, brassinin, sulforaphane, epigallocatechin-3-gallate, genistein, ellagitannins, lycopene and quercetin) have been found to inhibit one or more pathways that contribute to proliferation (e.g., hypoxia inducible factor 1, nuclear factor kappa B, phosphoinositide 3 kinase/Akt, insulin-like growth factor receptor 1, Wnt, cell cycle associated proteins, as well as androgen and estrogen receptor signaling). These data, in combination with bioinformatics analyses, will be very important for identifying signaling pathways and molecular targets that may provide early diagnostic markers and/or critical targets for the development of new drugs or drug combinations that block tumor formation and progression., Drs. Feitelson and Arzumanyan were supported by NIH (AI076535) and by Temple University. Dr. Rob J. Kulathinal was supported by the National Science Foundation, and by the American Cancer Society. Dr. Marino was supported by grant from University Roma Tre (CLA 2013) and by the Italian Association for Cancer Research (no. IG15221). Dr. Georgakilas was supported by the EU Marie Curie Reintegration Grant (MC-CIG-303514), Greek National funds through the Operational Program ‘Educational and Lifelong Learning of the National Strategic Reference Framework (NSRF)- Research Funding Program: THALES (MIS 379346) and COST Action CM1201 ‘Biomimetic Radical Chemistry.’ Dr. Amedei was supported by the Italian Ministry of University and University of Italy. Dr. Amin was supported by the Terry Fox Foundation (TF-36), UAEU Program for Advanced Research (UPAR25183), Al-Jalila Foundation (AJF201454) and Zayed Center for Health Sciences (ZCHS2014). Dr. Sanchez-Garcia was supported by FEDER, by MICINN (SAF2012-32810), by NIH (R01 CA109335-04A1), by Junta de Castilla y León (BIO/SA06/13), by the ARIMMORA project (FP7-ENV-2011, EU 7th Framework Program) and by the EuroSyStem and the DECIDE Network (EU FP7). Dr. Sharma was funded by NIH grants (R01CA131294, CA155686), the Avon Foundation and a Breast Cancer Research Foundation grant (90047965). Dr. Saxena was supported by a grant from NIH (K01DK077137 and R03DK089130). Dr. Singh was supported by the Fast Track Scheme for Young Scientists, Department of Science and Technology, India (SR/FT/LS-063/2008). Dr. Honoki was supported by a grant from the Ministry of Education, Culture, Sports, Science and Technology, Japan (no. 24590493). Dr. Ciriolo was supported by the Italian Association for Cancer Research (AIRC – grant #IG10636). Dr. Aquilano was supported by MIUR-PRIN (20125S38FA 002) and Ministero della Salute (GR-2011-02348047). Dr. Chen was funded from the Ovarian and Prostate Cancer Research Trust, UK. Dr. Mohammed is supported by the Purdue University Center for Cancer Research. W. Nicol Keith & Alan Bilsland were supported by the University of Glasgow, Beatson Oncology Centre Fund, and Cancer Research UK (http://www.cancerresearchuk.org) grant C301/A14762.

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the third leading cause of cancer death. The current view of cancer progression and malignancy supports the notion that cancer cells must undergo through a post-translational modification (PTM) regulation and a metabolic switch or reprogramming in order to progress in an unfriendly environment. NEDDylation is a post-translational modification of the proteins involved in several processes such as cell growth, viability and development. A ground-breaking knowledge on a new critical aspect of HCC research has been to identify that NEDDylation plays a role in HCC by regulating the liver oncogenic driver Hu antigen R (HuR). HuR is a RNA-binding protein that stabilizes target mRNAs involved in cell dedifferentiation, proliferation, and survival, all well-established hallmarks of cancer. And importantly, HuR levels were found to be highly representative in liver and colon cancer. These findings open a completely new area of research, exploring the impact that NEDDylation plays in liver diseases and paving the way for novel therapeutical approaches.

Nature 547, 109–113 (2017); doi:10.1038/nature22964 In this Letter, there are errors in Extended Data Figs 5, 8 and 9, and the affiliation of an author. The affiliations for author Violeta Serra should include number 2 (CIBERONC, Instituto de Salud Carlos III, C/ Monforte de Lemos 3-5, Pabellon 11, Planta 0, 28029 Madrid, Spain).

Osteopontin (OPN), a multifunctional cytokine that controls liver glycerolipid metabolism, is involved in activation and proliferation of several liver cell types during regeneration, a condition of high metabolic demands. Here we investigated the role of OPN in modulating the liver lipidome during regeneration after partial-hepatectomy (PH) and the impact that atorvastatin treatment has over regeneration in OPN knockout (KO) mice. The results showed that OPN deficiency leads to remodeling of phosphatidylcholine and triacylglycerol (TG) species primarily during the first 24 h after PH, with minimal effects on regeneration. Changes in the quiescent liver lipidome in OPN-KO mice included TG enrichment with linoleic acid and were associated with higher lysosome TG-hydrolase activity that maintained 24 h after PH but increased in WT mice. OPN-KO mice showed increased beta-oxidation 24 h after PH with less body weight loss. In OPN-KO mice, atorvastatin treatment induced changes in the lipidome 24 h after PH and improved liver regeneration while no effect was observed 48 h post-PH. These results suggest that increased dietary-lipid uptake in OPN-KO mice provides the metabolic precursors required for regeneration 24 h and 48 h after PH. However, atorvastatin treatment offers a new metabolic program that improves early regeneration when OPN is deficient. This work was supported by IT-336-10 (Gobierno Vasco) (to PA) and SAF2015-64352-R (to PA), SAF2017-87301-R (to MLM-C) and EITB Maratoia BIO15/CA/014 (to MLM-C). MNG and DM were recipients of a predoctoral fellowship from the University of Basque Country UPV/EHU and BG-S and DS were recipients for predoctoral fellowships from the Basque Goverment. We thank technical support from Jose Antonio Lopez Gomez.

Aims: We showed that chronic cholestatic liver injury induced the expression of c-Myc but suppressed that of glutamate-cysteine ligase (GCL, composed of catalytic and modifier subunits GCLC and GCLM, respectively). This was associated with reduced nuclear antioxidant response element (ARE) binding by nuclear factor-erythroid 2 related factor 2 (Nrf2). Here, we examined whether c-Myc is involved in this process. Results: Similar to bile duct ligation (BDL), lithocholic acid (LCA) treatment in vivo induced c-Myc but suppressed GCL subunits expression at day 14. Nrf2 expression and Nrf2 ARE binding fell markedly. However, Nrf2 heterodimerization with MafG was enhanced by LCA, which prompted us to examine whether LCA treatment in vivo altered proteins that bind to ARE using biotinylated ARE in pull-down assay followed by proteomics. LCA treatment enhanced c-Myc but lowered prohibitin 1 (PHB1) binding to ARE. This was a result of c-Myc-mediated induction of microRNA 27a/b (miR27a/b), which target both PHB1 and Nrf2 to reduce their expression. Knockdown of c-Myc or miR27a/b attenuated LCA-mediated suppression of Nrf2, PHB1, and GCL subunit expression, whereas overexpression of PHB1 protected against the fall in Nrf2 and GCL subunits. Both c-Myc and PHB1 directly interact with Nrf2 but c-Myc lowers Nrf2 binding to ARE while PHB1 enhances it. Innovation: This is the first work that shows how activation of this circuit in cholestatic liver injury inhibits GCL expression. Conclusions: LCA feeding and BDL activate c-Myc-miR27a/b-PHB1 circuit, with the consequence of inhibiting Nrf2 expression and ARE binding, resulting in decreased reduced glutathione synthesis and antioxidant capacity. Antioxid. Redox Signal. 22, 259–274.

Although Schwann cell myelin breakdown is the universal outcome of a remarkably wide range of conditions that cause disease or injury to peripheral nerves, the cellular and molecular mechanisms that make Schwann cell–mediated myelin digestion possible have not been established. We report that Schwann cells degrade myelin after injury by a novel form of selective autophagy, myelinophagy. Autophagy was up-regulated by myelinating Schwann cells after nerve injury, myelin debris was present in autophagosomes, and pharmacological and genetic inhibition of autophagy impaired myelin clearance. Myelinophagy was positively regulated by the Schwann cell JNK/c-Jun pathway, a central regulator of the Schwann cell reprogramming induced by nerve injury. We also present evidence that myelinophagy is defective in the injured central nervous system. These results reveal an important role for inductive autophagy during Wallerian degeneration, and point to potential mechanistic targets for accelerating myelin clearance and improving demyelinating disease.

HuR/ELAVL1 is an RNA-binding protein involved in differentiation and stress response that acts primarily by stabilizing messenger RNA (mRNA) targets. HuR comprises three RNA recognition motifs (RRMs) where the structure and RNA binding of RRM3 and of full-length HuR remain poorly understood. Here, we report crystal structures of RRM3 free and bound to cognate RNAs. Our structural, NMR and biochemical data show that RRM3 mediates canonical RNA interactions and reveal molecular details of a dimerization interface localized on the -helical face of RRM3. NMR and SAXS analyses indicate that the three RRMs in full-length HuR are flexibly connected in the absence of RNA, while they adopt a more compact arrangement when bound to RNA. Based on these data and crystal structures of tandem RRM1,2- RNA and our RRM3-RNA complexes, we present a structural model of RNA recognition involving all three RRM domains of full-length HuR. Mutational analysis demonstrates that RRM3 dimerization and RNA binding is required for functional activity of fulllength HuR in vitro and to regulate target mRNAs levels in human cells, thus providing a fine-tuning for HuR activity in vivo.

Nonalcoholic steatohepatitis (NASH) is the advanced form of nonalcoholic fatty liver disease (NAFLD) that sets the stage for further liver damage. The mechanism for the progression of NASH involves multiple parallel hits, including oxidative stress, mitochondrial dysfunction, inflammation, and others. Manipulation of any of these pathways may be an approach to prevent NASH development and progression. Arachidyl‐amido cholanoic acid (Aramchol) is presently in a phase IIb NASH study. The aim of the present study was to investigate Aramchol's mechanism of action and its effect on fibrosis using the methionine‐ and choline‐deficient (MCD) diet model of NASH. We collected liver and serum from mice fed an MCD diet containing 0.1% methionine (0.1MCD) for 4 weeks; these mice developed steatohepatitis and fibrosis. We also collected liver and serum from mice receiving a control diet, and metabolomes and proteomes were determined for both groups. The 0.1MCD‐fed mice were given Aramchol (5 mg/kg/day for the last 2 weeks), and liver samples were analyzed histologically. Aramchol administration reduced features of steatohepatitis and fibrosis in 0.1MCD‐fed mice. Aramchol down‐regulated stearoyl‐coenyzme A desaturase 1, a key enzyme involved in triglyceride biosynthesis and the loss of which enhances fatty acid β‐oxidation. Aramchol increased the flux through the transsulfuration pathway, leading to a rise in glutathione (GSH) and the GSH/oxidized GSH ratio, the main cellular antioxidant that maintains intracellular redox status. Comparison of the serum metabolomic pattern between 0.1MCD‐fed mice and patients with NAFLD showed a substantial overlap. Conclusion: Aramchol treatment improved steatohepatitis and fibrosis by 1) decreasing stearoyl‐coenyzme A desaturase 1 and 2) increasing the flux through the transsulfuration pathway maintaining cellular redox homeostasis. We also demonstrated that the 0.1MCD model resembles the metabolic phenotype observed in about 50% of patients with NAFLD, which supports the potential use of Aramchol in NASH treatment. (Hepatology Communications 2017;1:911–927)

Summary Thyroid hormones (THs) act in the brain to modulate energy balance. We show that central triiodothyronine (T3) regulates de novo lipogenesis in liver and lipid oxidation in brown adipose tissue (BAT) through the parasympathetic (PSNS) and sympathetic nervous system (SNS), respectively. Central T3 promotes hepatic lipogenesis with parallel stimulation of the thermogenic program in BAT. The action of T3 depends on AMP-activated protein kinase (AMPK)-induced regulation of two signaling pathways in the ventromedial nucleus of the hypothalamus (VMH): decreased ceramide-induced endoplasmic reticulum (ER) stress, which promotes BAT thermogenesis, and increased c-Jun N-terminal kinase (JNK) activation, which controls hepatic lipid metabolism. Of note, ablation of AMPKα1 in steroidogenic factor 1 (SF1) neurons of the VMH fully recapitulated the effect of central T3, pointing to this population in mediating the effect of central THs on metabolism. Overall, these findings uncover the underlying pathways through which central T3 modulates peripheral metabolism., Graphical Abstract, Highlights • Central T3 regulates lipogenesis in liver via the parasympathetic nervous system • Central T3 regulates lipid oxidation in BAT via the sympathetic nervous system • Ablation of AMPK in SF1 neurons of the VMH recapitulates the effects of T3 • Hypothalamic JNK1 and ceramides/ER stress mediate T3 actions on liver and BAT, Martínez-Sánchez et al. show that thyroid hormones act in the hypothalamus to regulate hepatic lipogenesis and brown fat lipid oxidation via the parasympathetic and sympathetic nervous systems. These peripheral effects are orchestrated by two distinct signaling pathways in the VMH, JNK1 and ceramides/ER stress, which are under AMPK control.

Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use: http://www.nature.com/authors/editorial_policies/license.html#terms Activation of the PTEN-PI3K-mTORC1 pathway consolidates metabolic programs that sustain cancer cell growth and proliferation,. Here we show that mTORC1 regulates polyamine dynamics, a metabolic route that is essential for oncogenicity. Through the use of integrative metabolomics in a mouse model and human biopsies of prostate cancer, we identified alterations in tumours impacting on the production of decarboxylated S-adenosylmethionine (dcSAM) and polyamine synthesis. Mechanistically, this metabolic rewiring stems from mTORC1-dependent regulation of S-adenosylmethionine decarboxylase 1 (AMD1) stability. This novel molecular regulation was validated in murine and human cancer specimens. AMD1 was upregulated in prostate cancer specimens with activated mTORC1. Conversely, samples from a clinical trial with the mTORC1 inhibitor everolimus exhibited a predominant decrease in AMD1 immunoreactivity that was associated to a decrease in proliferation, in line with the requirement of dcSAM production for oncogenicity. These findings provide fundamental information about the complex regulatory landscape controlled by mTORC1 to integrate and translate growth signals into an oncogenic metabolic program.

Sirtuin1 (SIRT1) regulates central metabolic functions such as lipogenesis, protein synthesis, gluconeogenesis, and bile acid (BA) homeostasis through deacetylation. Here we describe that SIRT1 tightly controls the regenerative response of the liver. We performed partial hepatectomy (PH) to transgenic mice that overexpress SIRT1 (SIRT). SIRT mice showed increased mortality, impaired hepatocyte proliferation, BA accumulation, and profuse liver injury after surgery. The damaging phenotype in SIRT mice correlated with impaired farnesoid X receptor (FXR) activity due to persistent deacetylation and lower protein expression that led to decreased FXR-target gene expression; small heterodimer partner (SHP), bile salt export pump (BSEP), and increased Cyp7A1. Next, we show that 24-norUrsodeoxycholic acid (NorUDCA) attenuates SIRT protein expression, increases the acetylation of FXR and neighboring histones, restores trimethylation of H3K4 and H3K9, and increases miR34a expression, thus reestablishing BA homeostasis. Consequently, NorUDCA restored liver regeneration in SIRT mice, which showed increased survival and hepatocyte proliferation. Furthermore, a leucine-enriched diet restored mammalian target of rapamycin (mTOR) activation, acetylation of FXR and histones, leading to an overall lower BA production through SHP-inhibition of Cyp7A1 and higher transport (BSEP) and detoxification (Sult2a1) leading to an improved liver regeneration. Finally, we found that human hepatocellular carcinoma (HCC) samples have increased presence of SIRT1, which correlated with the absence of FXR, suggesting its oncogenic potential. Conclusion: We define SIRT1 as a key regulator of the regenerative response in the liver through posttranscriptional modifications that regulate the activity of FXR, histones, and mTOR. Moreover, our data suggest that SIRT1 contributes to liver tumorigenesis through dysregulation of BA homeostasis by persistent FXR deacetylation. (Hepatology 2014;59:1972–1983)

Prohibitin 1 (PHB1) is best known as a mitochondrial chaperone, and its role in cancer is conflicting. Mice lacking methionine adenosyltransferase α1 (MATα1) have lower PHB1 expression, and we reported that c-MYC interacts directly with both proteins. Furthermore, c-MYC and MATα1 exert opposing effects on liver cancer growth, prompting us to examine the interplay between PHB1, MATα1, and c-MYC and PHB1's role in liver tumorigenesis. We found that PHB1 is highly expressed in normal hepatocytes and bile duct epithelial cells and down-regulated in most human hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). In HCC and CCA cells, PHB1 expression correlates inversely with growth. PHB1 and MAT1A positively regulate each other's expression, whereas PHB1 negatively regulates the expression of c-MYC, MAFG, and c-MAF. Both PHB1 and MATα1 heterodimerize with MAX, bind to the E-box element, and repress E-box promoter activity. PHB1 promoter contains a repressive E-box element and is occupied mainly by MAX, MNT, and MATα1 in nonmalignant cholangiocytes and noncancerous tissues that switched to c-MYC, c-MAF, and MAFG in cancer cells and human HCC/CCA. All 8-month-old liver-specific Phb1 knockout mice developed HCC, and one developed CCA. Five-month-old Phb1 heterozygotes, but not Phb1 flox mice, developed aberrant bile duct proliferation; and one developed CCA 3.5 months after left and median bile duct ligation. Phb1 heterozygotes had a more profound fall in the expression of glutathione synthetic enzymes and higher hepatic oxidative stress following left and median bile duct ligation. Conclusion: We have identified that PHB1, down-regulated in most human HCC and CCA, heterodimerizes with MAX to repress the E-box and positively regulates MAT1A while suppressing c-MYC, MAFG, and c-MAF expression; in mice, reduced PHB1 expression predisposes to the development of cholestasis-induced CCA. (Hepatology 2017;65:1249-1266).

Patient stratification has been instrumental for the success of targeted therapies in breast cancer. However, the molecular basis of metastatic breast cancer and its therapeutic vulnerabilities remain poorly understood. Here we show that PML is a novel target in aggressive breast cancer. The acquisition of aggressiveness and metastatic features in breast tumours is accompanied by the elevated PML expression and enhanced sensitivity to its inhibition. Interestingly, we find that STAT3 is responsible, at least in part, for the transcriptional upregulation of PML in breast cancer. Moreover, PML targeting hampers breast cancer initiation and metastatic seeding. Mechanistically, this biological activity relies on the regulation of the stem cell gene SOX9 through interaction of PML with its promoter region. Altogether, we identify a novel pathway sustaining breast cancer aggressiveness that can be therapeutically exploited in combination with PML-based stratification., Targeting PML in acute promyelocytic leukaemia has changed the outcome of patients with this disease. Here, the authors demonstrated that PML is also a potential therapeutic target in breast cancer where it specifically regulates cancer initiating cells and tumour progression through the transcriptional regulation of SOX9.

To elucidate the mechanism(s) by which S-adenosyl-L-methionine (SAM) decreases hepatitis C virus (HCV) expression.We examined the effects of SAM on viral expression using an HCV subgenomic replicon cell culture system. Huh7 HCV-replicon cells were treated with 1 mmol/L SAM for different times (24-72 h), then total RNA and proteins were isolated. cDNA was synthesized and real time-PCR was achieved to quantify HCV-RNA, superoxide dismutase 1 and 2 (SOD-1, SOD-2) catalase, thioredoxin 1, methionine adenosyltransferase 1A and 2A (MAT1A, MAT2A) expression, and GAPDH and RPS18 as endogenous genes. Expression of cellular and viral protein was evaluated by western-blot analysis using antibodies vs HCV-NS5A, SOD-1, SOD-2, catalase, thioredoxin-1, MAT1A, MAT2A, GAPDH and actin. Total glutathione levels were measured at different times by Ellman's recycling method (0-24 h). Reactive oxidative species (ROS) levels were quantified by the dichlorofluorescein assay (0-48 h); Pyrrolidin dithiocarbamate (PDTC) was tested as an antioxidant control and H2O2 as a positive oxidant agent.SAM exposition decreased HCV-RNA levels 50%-70% compared to non-treated controls (24-72 h). SAM induced a synergic antiviral effect with standard IFN treatment but it was independent of IFN signaling. In addition, 1 mmol/L SAM exposition did not modify viral RNA stability, but it needs cellular translation machinery in order to decrease HCV expression. Total glutathione levels increased upon SAM treatment in HCV-replicon cells. Transcriptional antioxidant enzyme expression (SOD-1, SOD-2 and thioredoxin-1) was increased at different times but interestingly, there was no significant change in ROS levels upon SAM treatment, contrary to what was detected with PDTC treatment, where an average 40% reduction was observed in exposed cells. There was a turnover from MAT1A/MAT2A, since MAT1A expression was increased (2.5 fold-times at 48 h) and MAT2A was diminished (from 24 h) upon SAM treatment at both the transcriptional and translational level.A likely mechanism(s) by which SAM diminish HCV expression could involve modulating antioxidant enzymes, restoring biosynthesis of glutathione and switching MAT1/MAT2 turnover in HCV expressing cells.

BACKGROUND & AIMS: Nonalcoholic fatty liver disease(NAFLD) is a consequence of defects in diverse metabolic pathwaysthat involve hepatic accumulation of triglycerides. Featuresof these aberrations might determine whether NAFLD progressesto nonalcoholic steatohepatitis (NASH). We investigated whetherthe diverse defects observed in patients with NAFLD are causedby different NAFLD subtypes with specific serum metabolomicprofiles, and whether these can distinguish patients with NASHfrom patients with simple steatosis. METHODS: We collectedliver and serum from methionine adenosyltransferase 1aknockout (MAT1A-KO) mice, which have chronically low levelsof hepatic S-adenosylmethionine (SAMe) and spontaneouslydevelop steatohepatitis, as well as C57Bl/6 mice (controls); themetabolomes of all samples were determined. We also analyzedserum metabolomes of 535 patients with biopsy-proven NAFLD(353 with simple steatosis and 182 with NASH) and comparedthem with serum metabolomes of mice. MAT1A-KO mice werealso given SAMe (30 mg/kg/day for 8 weeks); liver sampleswere collected and analyzed histologically for steatohepatitis. RESULTS: Livers of MAT1A-KO mice were characterized by highlevels of triglycerides, diglycerides, fatty acids, ceramides, andoxidized fatty acids, as well as low levels of SAMe and downstreammetabolites. There was a correlation between liver andserum metabolomes. We identified a serum metabolomicsignature associated with MAT1A-KO mice that also was presentin 49% of the patients; based on this signature, we identified 2NAFLD subtypes. We identified specific panels of markers thatcould distinguish patients with NASH from patients with simplesteatosis for each subtype of NAFLD. Administration of SAMereduced features of steatohepatitis in MAT1A-KO mice. CONCLUSIONS:In an analysis of serum metabolomes of patientswith NAFLD and MAT1A-KO mice with steatohepatitis, weidentified 2 major subtypes of NAFLD and markers that differentiatesteatosis from NASH in each subtype. These might beused to monitor disease progression and identify therapeutictargets for patients.

RNA-binding proteins (RBPs) play a major role in the control of messenger RNA (mRNA) turnover and translation rates. We examined the role of the RBP, human antigen R (HuR), during cholestatic liver injury and hepatic stellate cell (HSC) activation. HuR silencing attenuated fibrosis development in vivo after BDL, reducing liver damage, oxidative stress, inflammation, and collagen and alpha smooth muscle actin (α-SMA) expression. HuR expression increased in activated HSCs from bile duct ligation mice and during HSC activation in vitro, and HuR silencing markedly reduced HSC activation. HuR regulated platelet-derived growth factor (PDGF)-induced proliferation and migration and controlled the expression of several mRNAs involved in these processes (e.g., Actin, matrix metalloproteinase 9, and cyclin D1 and B1). These functions of HuR were linked to its abundance and cytoplasmic localization, controlled by PDGF, by extracellular signal-regulated kinases (ERK) and phosphatidylinositol 3-kinase activation as well as ERK/LKB1 (liver kinase B1) activation, respectively. More important, we identified the tumor suppressor, LKB1, as a novel downstream target of PDGF-induced ERK activation in HSCs. HuR also controlled transforming growth factor beta (TGF-β)-induced profibrogenic actions by regulating the expression of TGF-β, α-SMA, and p21. This was likely the result of an increased cytoplasmic localization of HuR, controlled by TGF-β-induced p38 mitogen-activated protein kinase activation. Finally, we found that HuR and LKB1 (Ser428) levels were highly expressed in activated HSCs in human cirrhotic samples. Conclusion: Our results show that HuR is important for the pathogenesis of liver fibrosis development in the cholestatic injury model, for HSC activation, and for the response of activated HSC to PDGF and TGF-β. (HEPATOLOGY 2012;56:1870–1882)

The enzyme AMP-activated protein kinase (AMPK) is the main energy sensor in cells and is responsible for controlling the balance of anabolic/catabolic processes under metabolic stress conditions. This metabolic control exerted by AMPK is critical for energy-demanding situations, such as liver regeneration. Immediately after partial hepatectomy (PH), the liver undergoes the priming phase, mediated by the proinflammatory cytokines tumor necrosis factor (TNF) and interleukin-6, which promote responsiveness of hepatocytes to growth factors, such as hepatocyte growth factor (HGF) and epidermal growth factor, which lead to proliferation. In addition to its metabolic function, AMPK is likely to be a key mediator in both hepatocyte priming and the proliferative phases, induced by TNF- α and HGF, respectively. TNF- α-induced AMPK activation has been shown to be necessary for nuclear factor κappa B (NF- κB)-induced inducible nitric oxide synthase expression and for blocking TNF- α-induced apoptosis. On the other hand, HGF-induced LKB1/AMPK activation has been found to play a critical role in controlling Hu antigen R cytosolic localization and endothelial nitric oxide synthase activation, and consequently Cyclin D1 and Cyclin A expressions, and nitric oxide generation, respectively. During PH, levels of S-adenosylmethionine (SAMe), the principal methyl donor in the liver, have to decrease to allow liver proliferation. Our studies also show that SAMe inhibits hepatocyte proliferation by controlling the hepatocyte's responsiveness to mitogenic signals such as HGF through the inhibition of AMPK activity. In summary, these data highlight the essential role of AMPK in controlling the balance between hepatocyte metabolic adaptations, cell cycle progression and apoptosis during liver regeneration.

Intercellular communication via GAP Junctions plays an important role in tissue homeostasis, apoptosis, carcinogenesis, cell proliferation and differentiation. Hepatocyte connexins (Cx) 26 and 32 levels are decreased during the de-differentiation process of primary hepatocytes in culture, a situation that is also characterized by a decrease in S-Adenosylmethionine (SAMe) levels. In this current study, we show that SAMe supplementation in cultured hepatocytes every 12h, leads to an up-regulation of Cx26 and 32 mRNA and protein levels and blocks culture-induced Cx43 expression, although it failed to increase Cx26 and 32 membrane localization and GAP junction intracellular communication. SAMe reduced nuclear β-catenin accumulation, which is known to stimulate the TCF/LEF-dependent gene transcription of Cx43. Moreover SAMe-induced reduction in Cx43 and β-catenin was prevented by the proteasome inhibitor MG132, and was not mediated by GSK3 activity. SAMe, and its metabolite 5'-methylthioadenosine (MTA) increased Cx26 mRNA in a process partially mediated by Adenosine A(2A) receptors but independent of PKA. Finally livers from MAT1A knockout mice, characterized by low hepatic SAMe levels, express higher Cx43 and lower Cx26 and 32 protein levels than control mice. These results suggest that SAMe maintains a characteristic expression pattern of the different Cxs in hepatocytes by differentially regulating their levels.

Dyslipidemia and hepatic overproduction of very low density lipoprotein (VLDL) are hallmarks of the septic response, yet the underlying mechanisms are not fully defined. We evaluated the lipoprotein subclasses profile and hepatic VLDL assembly machinery over 24 h in fasted LPS-treated rats. The response of serum non-esterified fatty acids (NEFA) and glucose to endotoxin was biphasic, with increased levels of NEFA and hypoglycemia in the first 12 h-phase, and low NEFA and high glucose in the second 12 h-phase. Hypertriglyceridemia was more marked in the first 12 h (6.8-fold), when triglyceride abundance increased in all lipoprotein subclasses, and preferentially in large VLDL. The abundance of medium-sized VLDL and the increase in the number of VLDL particles was higher in the second phase (10-fold vs 5-fold in the first phase); however, apoB gene transcript abundance increased only in the second phase. Analysis of putative pre-translational mechanisms revealed that neither increased Apob transcription rate nor increased transcript binding to mRNA stabilizing HuR (Hu antigen R) protein paralleled the increase in apoB transcripts. In conclusion, endotoxin challenge induces increases in plasma NEFA and large, triglyceride-rich VLDL. After approximately 12 h, the triglyceride-rich VLDLs are replaced by medium-sized, triglyceride-poor VLDL particles. Hepatic apoB mRNA abundance also increases during the second period, suggesting a role for apoB protein expression in the acute reaction against sepsis.

LKB1, originally considered a tumor suppressor, plays an important role in hepatocyte proliferation and liver regeneration. Mice lacking the methionine adenosyltransferase (MAT) gene MAT1A exhibit a chronic reduction in hepatic S-adenosylmethionine (SAMe) levels, basal activation of LKB1, and spontaneous development of nonalcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC). These results are relevant for human health because patients with liver cirrhosis, who are at risk to develop HCC, have a marked reduction in hepatic MAT1A expression and SAMe synthesis. In this study, we isolated a cell line (SAMe-deficient [SAMe-D]) from MAT1A knockout (MAT1A-KO) mouse HCC to examine the role of LKB1 in the development of liver tumors derived from metabolic disorders. We found that LKB1 is required for cell survival in SAMe-D cells. LKB1 regulates Akt-mediated survival independent of phosphoinositide 3-kinase, adenosine monophosphate protein-activated kinase (AMPK), and mammalian target of rapamycin complex (mTORC2). In addition, LKB1 controls the apoptotic response through phosphorylation and retention of p53 in the cytoplasm and the regulation of herpesvirus-associated ubiquitin-specific protease (HAUSP) and Hu antigen R (HuR) nucleocytoplasmic shuttling. We identified HAUSP as a target of HuR. Finally, we observed cytoplasmic staining of p53 and p-LKB1(Ser428) in a NASH-HCC animal model (from MAT1A-KO mice) and in liver biopsies obtained from human HCC derived from both alcoholic steatohepatitis and NASH. CONCLUSION: The SAMe-D cell line is a relevant model of HCC derived from NASH disease in which LKB1 is the principal conductor of a new regulatory mechanism and could be a practical tool for uncovering new therapeutic strategies. Fil: Martínez López, Nuria. Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas; España Fil: Varela Rey, Marta. Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas; España Fil: Fernández Ramos, David. Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas; España Fil: Woodhoo, Ashwin. Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas; España Fil: Vázquez Chantada, Mercedes. Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas; España Fil: Embade, Nieves. Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas; España Fil: Espinosa Hevia, Luis. Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas; España Fil: Bustamante, Francisco Javier. Universidad del País Vasco. Hospital de Cruces; España Fil: Parada, Luis Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Patología Experimental. Universidad Nacional de Salta. Facultad de Ciencias de la Salud. Instituto de Patología Experimental; Argentina Fil: Rodriguez, Manuel S.. Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas. Parque Tecnológico de Bizkaia; España Fil: Lu, Shelly C.. University of Southern California. Keck School of Medicine. Division of Gastrointestinal and Liver Diseases; Estados Unidos Fil: Mato, José M.. Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas; España Fil: Martínez Chantar, María L.. Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas; España