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Friedreich ataxia (FA) is a rare neurodegenerative disease caused by decreased levels of the mitochondrial protein frataxin. Frataxin has been related in iron homeostasis, energy metabolism, and oxidative stress. Ferroptosis has recently been shown to be involved in FA cellular degeneration; however, its role in dorsal root ganglion (DRG) sensory neurons, the cells that are affected the most and the earliest, is mostly unknown. In this study, we used primary cultures of frataxin-deficient DRG neurons as well as DRG from the FXNI151F mouse model to study ferroptosis and its regulatory pathways. A lack of frataxin induced upregulation of transferrin receptor 1 and decreased ferritin and mitochondrial iron accumulation, a source of oxidative stress. However, there was impaired activation of NRF2, a key transcription factor involved in the antioxidant response pathway. Decreased total and nuclear NRF2 explains the downregulation of both SLC7A11 (a member of the system Xc, which transports cystine required for glutathione synthesis) and glutathione peroxidase 4, responsible for increased lipid peroxidation, the main markers of ferroptosis. Such dysregulation could be due to the increase in KEAP1 and the activation of GSK3β, which promote cytosolic localization and degradation of NRF2. Moreover, there was a deficiency in the LKB1/AMPK pathway, which would also impair NRF2 activity. AMPK acts as a positive regulator of NRF2 and it is activated by the upstream kinase LKB1. The levels of LKB1 were reduced when frataxin decreased, in agreement with reduced pAMPK (Thr172), the active form of AMPK. SIRT1, a known activator of LKB1, was also reduced when frataxin decreased. MT-6378, an AMPK activator, restored NRF2 levels, increased GPX4 levels and reduced lipid peroxidation. In conclusion, this study demonstrated that frataxin deficiency in DRG neurons disrupts iron homeostasis and the intricate regulation of molecular pathways affecting NRF2 activation and the cellular response to oxidative stress, leading to ferroptosis.

Objective Objective To investigate the changes in hippocampal astrocytes and neuronal primary cilia, and neuronal apoptosis in the offspring brain of advanced maternal age and the role of LKB1/AMPK pathway. Methods The 12-month-old SD female rats were mated with 3-month-old SD male rats to produce offspring as the advanced maternal age (AMA) group, and the 3-month-old SD female rats were mated with 3-month-old SD males to produce offspring as the appropriate age (Control, Ctl) group. The following studies were conducted on postnatal days 14, 28 and 60 (P14, P28 and P60) in the 2 groups (14 rats per group at each time point, half males and half females). HE staining and Nissl staining were used to observe the changes in the morphology and the number of hippocampal neurons and their internal Nissl bodies. Immunofluorescence assay was employed to detect the expression of hippocampal primary cilia marker, anti-ADP ribosylation factor-like protein-13B (ARL13B), and Western blotting was applied to measure the expression of hippocampal intraflagellar transport protein 88 (IFT88) to assess functional changes in primary ciliogenesis. TUNEL staining and Western blotting were performed to detect the expression levels of pro-apoptotic BAX, and anti-apoptotic protein, BCL-2 to observe the changes of apoptosis in the hippocampus. Western blotting was also used to detect the expression levels of liver kinase B1 (LKB1), adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR) and the levels of their corresponding phosphorylated proteins to assess LKB1/AMPK pathway changes. Results Compared with the Ctl group: HE staining and Nissl staining showed that the number of hippocampal neurons was significantly reduced in the AMA group at P14 (P < 0.05), and there were abnormal changes in hippocampal neuron morphology and Nissl body number and morphology in the AMA group at all time points; the incidence of ARL13B primary cilia was significantly decreased in the AMA group at both P14 (P < 0.05) and P28 (P < 0.001), and the length of ARL13B was obviously shortened in the AMA group at both P14 (P < 0.05) and P28 (P < 0.05); the hippocampal expression level of IFT88 was notably lower in the AMA group at the P14 (P < 0.01). TUNEL staining showed that the apoptotic rate of hippocampal neurons at P14 was remarkably higher in the AMA group (P < 0.05), while Western blotting indicated that the expression of BAX was significantly higher (P < 0.001) and that of BCL-2 was lower (P < 0.01). In the AMA group, the expression of p-LKB1 was significantly decreased at P14 (P < 0.05), that of p-AMPK was statistically elevated at P28 (P < 0.01) and P60 (P < 0.01), and that of p-mTOR was notably decreased at P60 (P < 0.05). Conclusion Neuronal damage, defective primary ciliogenesis and growth inhibition, and abnormal activation of apoptosis are present in the hippocampus of juvenile offspring brain of advanced maternal age. Meanwhile, the LKB1/AMPK pathway, which is regulated by primary cilia in hippocampal astrocytes and neurons of advanced maternal age offspring brain, is abnormally activated at all ages.

Ursolic acid (UA), a triterpenoid found in plants, has many health benefits for liver function. However, understanding how UA intervenes in alcohol-induced ferroptosis remains unclear because of the lack of research. This study explored the protective effects of UA on alcohol-induced liver injury and further elucidated its mechanism of action. Using a mouse model, acute liver injury was induced via high-dose alcohol gavage, and UA's protective effects were assessed by analyzing serum and liver indicators. The results indicated that UA has a significant protective effect against alcohol-induced liver injury in mice. UA significantly decreased serum ALT, AST, TC, and TG levels. Histopathological examination revealed that UA significantly ameliorated liver damage. UA increased ADH, ALDH, and CYP2E1 enzyme expression levels and alleviated alcohol-induced oxidative damage by regulating alcohol metabolism. Moreover, UA increased SOD and GSH-Px levels and lowered the MDA levels in the liver. Furthermore, UA regulated ACC expression by activating the LKB1/AMPK pathway, thereby inhibiting lipid synthesis and peroxidation. UA also upregulated the expression of GPX4 and SLC7A11 in the liver and exerted hepatoprotective effects by inhibiting alcohol-induced ferroptosis. Additionally, 16S rRNA amplicon sequencing showed that excessive alcohol consumption significantly affected the composition of the mouse gut microbiota, with UA intervention proving to be beneficial for improving gut microbiota imbalance. We also validated the protective effects of UA on alcohol-treated HepG2 cells at the cellular level. In summary, these results revealed that UA can alleviate alcoholic liver injury by inhibiting oxidative stress-mediated ferroptosis and regulating gut microbiota. These findings suggest that UA may serve as a functional component in the prevention of alcoholic liver disease.

Nasopharyngeal carcinoma (NPC) is a cancer that occurs in the nasopharynx. Infinite proliferation and distant metastasis are the main characteristics of NPC cells, and the main reason for the current failure of malignant tumor treatment. In this study, by integrating the immunohistochemical, cell transfection, western blot and real-time reverse transcriptase polymerase chain reaction (RT-PCR) analysis, we observed that the expression of KISS1 and its receptor gene (KISS1R) negatively related with the proliferation of NPC cells. Overexpression of the KISS1 genes in cells reduced cell proliferation, slow down the cell cycle, and increased apoptosis. Additionally, overexpression of these genes significantly increased Liver Kinase B1 (LKB1), phosphorylation of LKB1 and AMPK, indicated by Western blotting. Together, all of these results suggested for the first time that KISS1 and KISS1R suppress the proliferation of NPC cells by activating the LKB1/AMPK pathway, thus revealing a viable indicator for diagnosis of NPC in clinical practice.

Nasopharyngeal carcinoma (NPC) is a cancer that occurs in the nasopharynx. Infinite proliferation and distant metastasis are the main characteristics of NPC cells, and the main reason for the current failure of malignant tumor treatment. In this study, by integrating the immunohistochemical, cell transfection, western blot and real-time reverse transcriptase polymerase chain reaction (RT-PCR) analysis, we observed that the expression of KISS1 and its receptor gene (KISS1R) negatively related with the proliferation of NPC cells. Overexpression of the KISS1 genes in cells reduced cell proliferation, slow down the cell cycle, and increased apoptosis. Additionally, overexpression of these genes significantly increased Liver Kinase B1 (LKB1), phosphorylation of LKB1 and AMPK, indicated by Western blotting. Together, all of these results suggested for the first time that KISS1 and KISS1R suppress the proliferation of NPC cells by activating the LKB1/AMPK pathway, thus revealing a viable indicator for diagnosis of NPC in clinical practice. [ABSTRACT FROM AUTHOR]

Although a mountain of papers have showed that metformin plays a role in inhibiting cancers, but the mechanism underpinning this has not yet fully elucidated. Herein, we used AOM/DSS model, the clinicopathological features are similar to those found in humans, to investigate the effects of metformin as well as combination with 5-FU in the prevention of colitis and colitis associated cancer (CAC). Oral metformin significantly inhibited DSS-induced ulcerative colitis and AOM/DSS-induced CAC. Metformin also ameliorated 5-FU-induced colorectal gastrointestinal symptoms in mice. Metformin combination with 5-FU strongly inhibited colorectal cancer. Metformin reduced levels of the NFκB signaling components p-IKKα/β, p-NFκB, p-IκBα in colorectal mucosal cells. Transmission electron microscopy analysis suggested that the inhibition of metformin on colitis and CAC might associate with its biological activity of protecting mitochondrial structures of colorectal epithelial cells. Further analysis by Mito Tracker Red staining assay indicated that metformin prevented H2O2-induced mitochondrial fission correlated with a decrease of mitochondrial perimeter. In addition, metformin increased the level of NDUFA9, a Q-module subunit required for complex I assembly, in colorectal epithelial cells. These observations of metformin in the inhibition of colitis and CAC might associate with its activity of activating the LKB1/AMPK pathway in colorectal epithelial cells. In conclusion, metformin inhibited colitis and CAC through protecting the mitochondrial structures of colorectal epithelial cells. [ABSTRACT FROM AUTHOR]

ABSTRACT Odanacatib (ODN) is a selective inhibitor of cathepsin K. The cysteine protease cathepsin K has been implicated in cardiac hypertrophy. Resistine is an adipokine which is identified to promote cardiac hypertrophy. Here, we hypothesize that ODN mitigates resistin-induced myocyte hypertrophy. Cell surface area and protein synthesis were measured after treatment with resistin and ODN in H9c2 cells. The expression of cardiomyocyte hypertrophy marker BNP and β-MHC was detected by RT-qPCR. The expression and phosphorylation of AMPK and LKB1 were analyzed with Western blot. Resistin could significantly increase cardiomyocyte cell surface area, protein synthesis, and embryonic gene BNP and β-MHC expression, inhibit phosphorylation of AMPK and LKB1. ODN could significantly reverse the effects of resistin. Collectively, our data suggest that ODN can inhibit cardiomyocyte hypertrophy induced by resistin and the underlying mechanism may be involved in LKB1/AMPK pathway.

• Baicalin inhibits pressure overload-induced cardiac hypertrophy in vivo and in vitro. • Baicalin inhibits cardiac hypertrophy through activating SIRT3, but not SIRT1. • Ubiquitin-proteasome participated in Ang II-induced SIRT3 expression in cardiomyocytes. • Baicalin regulates protein expression of SIRT3 through proteasome inhibition. The conserved sirtuin protein sirtuin 3 (SIRT3) is a vital protective protein for cardiac hypertrophy. Inhibition of SIRT3 accelerated the development of heart hypertrophy. On the other hand, myocardial hypertrophy was prevented by overexpressing SIRT3. SIRT3 has been proposed as a potential therapeutic target for managing or averting heart hypertrophy. Baicalin, a flavonoid extracted from the Scutellaria baicalensis plant, has anti-cardiovascular properties, including protection against cardiac hypertrophy. However, the molecular mechanism of the anti-hypertrophic effect of baicalin is not well known. In this study, we aim to investigate the effect of baicalin on cardiac hypertrophy and explored its underlying molecular mechanisms. Abdominal aortic constriction (AAC)-induced mouse cardiac hypertrophy and angiotensin II (Ang II)-induced cardiomyocyte hypertrophy models were established. After baicalin treatment, cardiac hypertrophy was monitored by detecting the expression of hypertrophic genes and cell surface area. Echocardiogram was performed to check the heart function in vivo. Moreover, the protein expression of the SIRT3-dependent pathway was detected by Western blotting. In this work, we demonstrated that baicalin might suppress the cell surface area and the expression of the Ang II -induced myosin heavy chain β (β-MHC), brain natriuretic polypeptide (BNP), and atrial natriuretic factor (ANF). Additionally, it reduced the AAC rats' hypertrophic impact. We also found that baicalin prevents cardiac hypertrophy by regulating SIRT3/LKB1/AMPK signaling pathway. Moreover, we showed that baicalin upregulated the SIRT3 protein expression by inhibiting proteasome and by the activation of 20 S proteasome subunit beta type-5 (PSMB5). These results offer the first proof that baicalin inhibits cardiac hypertrophy due to its effect on the SIRT3-dependent signaling pathway, indicating its potential for treating cardiac hypertrophy and heart failure. The present study provides a preliminary experimental basis for the clinical application of baicalin and baicalin-like compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

Our previous studies demonstrated that vanadium(IV) complex with 4-chlorodipicolinic acid (VOdipic-Cl) alleviates lipid abnormalities in streptozotocin (STZ)-induced diabetic rats. However, the molecular mechanisms are not fully understood. In the present study, the effect of VOdipic-Cl on adipogenesis and mechanisms of action in 3T3-L1 preadipocytes were investigated. The 3T3-L1 preadipocytes were induced to differentiate in the presence or absence of VOdipic-Cl for 8 days. The cells were determined for proliferation, differentiation, lipid accumulation as well as the protein expressions of molecular targets that are involved in fatty acid synthesis. The results demonstrated that VOdipic-Cl at concentrations ranging from 2.5 μM to 10 μM reduced the intracellular lipid content by 10%, 22% and 30% compared to control. VOdipic-Cl down-regulated the expression of peroxisome proliferator-activated receptor (PPARγ), CCAAT element binding protein a (C/EBPα), sterol regulatory element binding protein 1c (SREBP-1c), fatty acid synthase (FAS) and fatty acid-binding protein 4 (FABP4) and activated the phosphorylation of acetyl coenzyme A carboxylase (ACC), adenosine monophosphate-activated protein kinase (AMPK) and liver kinase B1 (LKB1) in a dose-dependent manner. Further studies showed that AMPK small interfering RNA (siRNA) markedly up-regulated PPARγ, C/EBPα, FAS and FABP4 expression in the presence of VOdipic-Cl, respectively. When LKB1 was silenced with siRNA, the effect of VOdipic-Cl on AMPK phosphorylation was diminished. Taken together, these results suggested that VOdipic-Cl can inhibit 3T3-L1 preadipocyte differentiation and adipogenesis through activating the LKB1/AMPK-dependent signaling pathway. These findings raise the possibility that VOdipic-Cl may be a promising therapy in treatment of obesity. [ABSTRACT FROM AUTHOR]

Type 2 diabetes mellitus (T2DM)-induced cardiomyopathy is associated with cardiac oxidative stress, inflammation, and remodeling. Sulforaphane (SFN), an isothiocyanate naturally presenting in widely consumed vegetables, particularly broccoli, plays an important role in cardiac protection from diabetes. We investigated the effect of SFN on T2DM-induced cardiac lipid accumulation and subsequent cardiomyopathy. Male C57BL/6J mice were fed a high-fat diet for 3 months to induce insulin resistance, followed by a treatment with 100 mg/kg body-weight streptozotocin to induce hyperglycemia; we referred to it as the T2DM mouse model. Other age-matched mice were fed a normal diet as control. T2DM and control mice were treated with or without 4-month SFN at 0.5 mg/kg daily five days a week. At the study's end, cardiac function was assessed. SFN treatment significantly attenuated cardiac remodeling and dysfunction induced by T2DM. SFN treatment also significantly inhibited cardiac lipid accumulation, measured by Oil Red O staining, and improved cardiac inflammation oxidative stress and fibrosis, shown by down-regulating diabetes-induced PAI-1, TNF-α, CTGF, TGF-β, 3-NT, and 4-HNE expression. Elevated 4-HNE resulted in the increase of 4-HNE-LKB1 adducts that should inhibit LKB1 and subsequent AMPK activity. SFN upregulated the expression of Nrf2 and its downstream genes, NQO1 and HO-1, decreased 4-HNE-LKB1 adducts and then reversed diabetes-induced inhibition of LKB1/AMPK and its downstream targets, including sirtuin 1, PGC-1α, phosphorylated acetyl-CoA carboxylase, carnitine palmitoyl transferase-1, ULK1, and light chain-3 II. These results suggest that SFN treatment to T2DM mice may attenuate the cardiac oxidative stress-induced inhibition of LKB1/AMPK signaling pathway, thereby preventing T2DM-induced lipotoxicity and cardiomyopathy. [ABSTRACT FROM AUTHOR]

Background: Type 2 diabetes mellitus (DM) is a highly prevalent chronic metabolic disease. Effective antidiabetic drugs are needed to improve and expand the available treatments. Using the ob/ob diabetic mouse model, we previously demonstrated that the alkaloid-rich extract from Litsea glutinosa bark (CG) has potent antidiabetic effects and that laurolitsine (LL) is the richest alkaloid in CG., Purpose: We conducted a systematic investigation of the antidiabetic effects and potential mechanisms of LL in vitro and in vivo., Methods: The antidiabetic effects of LL and its mechanisms of action were explored in HL-7702 hepatocytes in vitro and in db/db mice in vivo by a series of experiments, including cellular toxicity analysis, glucose consumption analysis, serum/liver biochemical analysis, pathological examinations, Western blots, RNA-seq analysis, and gut microbiota analysis., Results: LL stimulated glucose consumption and activated AMP-activated protein kinase (AMPK) without inducing lactic acid production or cytotoxicity in vitro. LL had potent antidiabetic effects with hypoglycemic activity in vivo. It improved insulin resistance, glucose tolerance and lipid metabolism; protected liver, renal and pancreatic functions; and promoted weight loss in db/db mice. Transcriptomic analysis suggested that the antidiabetic effects of LL involved the regulation of mitochondrial oxidative phosphorylation. We further demonstrated that LL effectively activated the hepatic liver kinase B1 (LKB1)/AMPK pathway by regulating the ADP/ATP ratio. Simultaneously, LL significantly modulated the gut microbial community, specifically decreasing the abundances of Mucispirillum schaedleri and Anaerotruncus&#95;sp&#95;G3&#95;2012, which might also contribute to its antidiabetic effects., Conclusion: These results suggest that LL is a promising antidiabetic drug candidate that may improve glucolipid metabolism via modulation of the hepatic LKB1/AMPK pathway and the gut microbiota., Competing Interests: Declaration of Competing Interest All authors report no conflict of interest., (Copyright © 2022. Published by Elsevier GmbH.)