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Microplastics (MPs) and antibiotics often coexist in complex marine environments, yet their combined detrimental effects on marine organisms remain underexplored. This study evaluated the effects of polyethylene microplastics (PE, 200 μg/L) and sulfamethoxazole (SMX, 50 μg/L), both individually and in combination, on Mytilus galloprovincialis. The exposure lasted 6 days, followed by a 6-day recovery period. Bioaccumulation, DNA damage, pollutants transport/metabolism related responses and responding alterations of mitogen-activated protein kinase (MAPK) signaling pathway were detected in gills and digestive glands. Bioaccumulation of SMX/PE in mussels occurred in a tissue-specific manner, co-exposure altered SMX contents in investigated tissues. Co-exposure did not induce extra DNA damage, elevated DNA damage was alleviated during the recovery period in all treated groups. The exposure of SMX/PE exerted different alterations in pollutants transport/metabolism related responses, characterized by multixenobiotic resistance and relative expression of key genes (cytochrome P450 monooxygenase, glutathione S-transferase, ATP-binding cassette transporters). Key molecules (p38 MAPK, c-jun N-terminal kinase, extracellular regulated protein kinase, nuclear factor-κB and tumor protein p53) in MAPK signaling pathway were activated at transcriptional and translational levels after SMX/PE and co-exposure. Co-regulation between MAPK members and pollutants transport/metabolism related factors was revealed, suggesting MAPK signaling pathway served as a regulating hub in exposed mussels to conquer SMX/PE stress. Overall, this study provides new insights on SMX/PE induced health risks in marine mussels and potential mechanism through MAPK cascades regulation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Eukaryotic organisms are composed of different cell types with defined shapes and functions. Specific cell types are produced by the process of cell differentiation, which is regulated by signal transduction pathways. Signaling pathways regulate cell differentiation by sensing cues and controlling the expression of target genes whose products generate cell types with specific attributes. In studying how cells differentiate, fungi have proved valuable models because of their ease of genetic manipulation and striking cell morphologies. Many fungal species undergo filamentous growth-a specialized growth pattern where cells produce elongated tube-like projections. Filamentous growth promotes expansion into new environments, including invasion into plant and animal hosts by fungal pathogens. The same signaling pathways that regulate filamentous growth in fungi also control cell differentiation throughout eukaryotes and include highly conserved mitogen-activated protein kinase (MAPK) pathways, which is the focus of this review. In many fungal species, mucin-type sensors regulate MAPK pathways to control filamentous growth in response to diverse stimuli. Once activated, MAPK pathways reorganize cell polarity, induce changes in cell adhesion, and promote the secretion of degradative enzymes that mediate access to new environments. However, MAPK pathway regulation is complicated because related pathways can share components with each other yet induce unique responses (i.e. signal specificity). In addition, MAPK pathways function in highly integrated networks with other regulatory pathways (i.e. signal integration). Here, we discuss signal specificity and integration in several yeast models (mainly Saccharomyces cerevisiae and Candida albicans) by focusing on the filamentation MAPK pathway. Because of the strong evolutionary ties between species, a deeper understanding of the regulation of filamentous growth in established models and increasingly diverse fungal species can reveal fundamentally new mechanisms underlying eukaryotic cell differentiation., Competing Interests: Conflicts of interest The authors declare that there are no competing interests with this study. There are no new data associated with this article., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Genetics Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The retina is composed of neuronal layers that include several types of interneurons and photoreceptor cells, and separate underlying retinal pigment epithelium (RPE), Bruch's membrane, and choroid. Different regions of the human retina include the fovea, macula, and periphery, which have unique physiological functions and anatomical features. These regions are also unique in their protein expression, and corresponding cellular and molecular responses to physiological and pathophysiological stimuli. Skeie and Mahajan analyzed regional protein expression in the human choroid-RPE complex. Mitogen-Activated Protein Kinase (MAPK) signaling pathways have been implicated in responses to stimuli such as oxidative stress and inflammation, which are critical factors in retina diseases including age-related macular degeneration. We, therefore, analyzed the Skeie and Mahajan, 2014, dataset for regional differences in the expression of MAPK-related proteins and discussed the potential implications in retinal diseases presenting with regional signs and symptoms. Regional protein expression data from the Skeie and Mahajan, 2014, study were analyzed for members of signaling networks involving MAPK and MAPK-related proteins, categorized by specific MAPK cascades, such as p38, ERK1/2, and JNK1/2, both upstream or downstream of the respective MAPK and MAPK-related proteins. We were able to identify 207 MAPK and MAPK-related proteins, 187 of which belonging to specific MAPK cascades. A total of 31 of these had been identified in the retina with two proteins, DLG2 and FLG downstream, and the other 29 upstream, of MAPK proteins. Our findings provide evidence for potential molecular substrates of retina region-specific disease manifestation and potential new targets for therapeutics development.

Cells harbour numerous receptor pathways to respond to diverse stimuli, yet often share common downstream signalling components. Mitogen-activated protein kinase (MPK) cascades are an example of such common hubs in eukaryotes. How such common hubs faithfully transduce distinct signals within the same cell-type is insufficiently understood, yet of fundamental importance for signal integration and processing in plants. We engineered a unique genetic background allowing direct comparisons of a developmental and an immunity pathway in one cell-type, the Arabidopsis root endodermis. We demonstrate that the two pathways maintain distinct functional and transcriptional outputs despite common MPK activity patterns. Nevertheless, activation of different MPK kinases and MPK classes led to distinct functional readouts, matching observed pathway-specific readouts. On the basis of our comprehensive analysis of core MPK signalling elements, we propose that combinatorial activation within the MPK cascade determines the differential regulation of an endodermal master transcription factor, MYB36, that drives pathway-specific gene activation., (© 2024. The Author(s).)

IL-33 belongs to the inflammatory factor family and is closely associated with the inflammatory response. However, its role in the development of intrauterine adhesions (IUAs) remains unclear. In this study, the role of IL-33 in the formation of IUAs after endometrial injury was identified via RNA sequencing after mouse endometrial organoids were transplanted into an IUA mouse model. Major pathological changes in the mouse uterus, consistent with the expression of fibrotic markers, such as TGF-β, were observed in response to treatment with IL-33. This finding may be attributed to activation of the phosphorylation of downstream MAPK signaling pathway components, which are activated by the release of IL-33 in macrophages. Our study provides a novel mechanism for elucidating IUA formation, suggesting a new therapeutic strategy for the prevention and clinical treatment of IUAs., (© 2024. The Author(s).)

Mitogen-activated protein kinase (MAPK) pathways control the response to intrinsic and extrinsic stimuli. In the budding yeast Saccharomyces cerevisiae, cells undergo filamentous growth, which is regulated by the fMAPK pathway. To better understand the regulation of the fMAPK pathway, a genetic screen was performed to identify spontaneous mutants with elevated activity of an fMAPK pathway-dependent growth reporter (ste4  FUS1-HIS3). In total, 159 mutants were isolated and analyzed by secondary screens for invasive growth by the plate-washing assay and filament formation by microscopy. Thirty-two mutants were selected for whole-genome sequencing, which identified new alleles in genes encoding known regulators of the fMAPK pathway. These included gain-of-function alleles in STE11, which encodes the MAPKKK, as well as loss-of-function alleles in KSS1, which encodes the MAP kinase, and loss-of-function alleles in RGA1, which encodes a GTPase-activating protein (GAP) for CDC42. New alleles in previously identified pathway modulators were also uncovered in ALY1, AIM44, RCK2, IRA2, REG1, and in genes that regulate protein folding (KAR2), glycosylation (MNN4), and turnover (BLM10). Mutations leading to C-terminal truncations in the transcription factor Ste12p were also uncovered that resulted in elevated reporter activity, identifying an inhibitory domain of the protein from residues 491 to 688. We also find that a diversity of filamentous growth phenotypes can result from combinatorial effects of multiple mutations and by loss of different regulators of the response. The alleles identified here expand the connections surrounding MAPK pathway regulation and reveal new features of proteins that function in the signaling cascade., Competing Interests: Conflicts of interest The author(s) declare no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Genetics Society of America.)

Sclerotinia sclerotiorum causes white mold or stem rot in a wide range of economically important plants, bringing significant yield losses worldwide. Control of this pathogen is difficult as its resting structure sclerotia can survive in soil for years, and no Resistance genes have been identified in S. sclerotiorum hosts. Host-induced gene silencing (HIGS) has shown promising effects in controlling many fungal pathogens, including S. sclerotiorum. However, better molecular genetic understanding of signaling pathways involved in its development and pathogenicity is needed to provide effective HIGS gene targets. Here, by employing a forward genetic screen, we characterized an evolutionarily conserved mitogen-activated protein kinase (MAPK) cascade in S. sclerotiorum, consisting of SsSte50-SsSte11-SsSte7-Smk1, which controls mycelial growth, sclerotia development, compound appressoria formation, virulence, and hyphal fusion. Moreover, disruption of the putative downstream transcription factor SsSte12 led to normal sclerotia but deformed appressoria and attenuated host penetration, as well as impaired apothecia formation, suggestive of diverged regulation downstream of the MAPK cascade. Most importantly, targeting SsSte50 using host-expressed double-stranded RNA resulted in largely reduced virulence of S. sclerotiorum on both Nicotiana benthamiana leaves and transgenic Arabidopsis thaliana plants. Therefore, this MAPK signaling cascade is generally needed for its growth, development, and pathogenesis and can serve as ideal HIGS targets for mitigating economic damages caused by S. sclerotiorum infection., (© 2023 The Authors. The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.)

Plant yields are compromised due to abiotic and biotic stresses. A crucial biotic stress instigated by insect attack, is a major concern that limits crop production. To overcome the deleterious effect of herbivory, pesticides are used but long-term usage of pesticides can be harmful to the environment and human health. Understanding the plants' inherent defense mechanism by interpreting the interaction pattern of defense-related proteins and signalling components and manipulating them to strengthen defense status, is one of the alternative approaches of green biotechnology. During insect attack, host plants initiate innumerable signalling pathways to activate defense response; Mitogen Activated Protein Kinase (MAPK) Pathway is a crucial component of signalling pathway that regulate the expression of downstream defense-related genes. MAPK pathway has three components: MAPKKK, MAPKK and MAPK. Earlier studies have shown participation of SIPK and WIPK (MAPKs) as well as MEK2 (MAPKK) during insect infestation and its association with plant defense. However, information on the third component and elucidation of the complete MAPK pathway are still elusive. Therefore, this study aims to identify the unknown component and decipher MAPK pathway in Nicotiana attenuata involved in plant defense against herbivory by identifying herbivory-inducible MAPKKKs and and their interaction with known partners of the MAPK pathway by docking and MD simulation. The possible pathway was predicted to be MAPKKK Na 12134/ Na 04522-MEK2-SIPK/WIPK. Further, validation of the above interaction by in vitro and in vivo methods is highly recommended.Communicated by Ramaswamy H. Sarma.

Breast cancer (BC) is one of the most common malignancies occurring in women worldwide, and its incidence is increasing each year. Accumulating evidence indicated that Myosin VI (MYO6) functions as a gene associated with tumor progression in several cancers. However, the potential role of MYO6 and its underlying mechanisms in the development and progression of BC remains unknown. Herein, we examined the expression levels of MYO6 in BC cells and tissues by western blot and immunohistochemistry. Loss- and gain-of-function investigations in vitro were performed to determine the biological functions of MYO6. And in vivo effects of MYO6 on tumorigenesis were investigated in nude mice. Our findings showed that the expression of MYO6 was up-regulated in breast cancer, and its high expression was correlated with poor prognosis. Further investigation exhibited that silencing the expression of MYO6 significantly inhibited cell proliferation, migration and invasion, whereas overexpression of MYO6 enhanced these abilities in vitro. Also, reduced expression of MYO6 significantly retarded the tumor growth in vivo. Mechanistically, Gene Set Enrichment Analysis (GSEA) revealed that MYO6 was involved in mitogen-activated protein kinase (MAPK) pathway. Moreover, we proved that MYO6 enhanced BC proliferation, migration and invasion via increasing the expression of phosphorylated ERK1/2. Taken together, our findings highlight the role of MYO6 in promoting BC cell progression through MAPK/ERK pathway, suggesting it may be a new potential therapeutic and prognostic target for BC patients., Competing Interests: Declaration of Competing Interest The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Introduction: Previous studies have indicated the ERBB2 genetic variants in the 17q12 locus might be associated with asthma; however, the functional effects of these variants on asthma risk remain inconclusive. This study aimed to characterize the functional roles of asthma-associated ERBB2 single nucleotide polymorphisms (SNPs) in asthma pathogenesis by performing genetic association and functional analysis studies., Methods: This study belongs to a part of an ongoing Singapore/Malaysia cross-sectional genetics and epidemiological study (SMCSGES). Genotype-phenotype associations were assessed by performing a genotyping assay on n = 4,348 ethnic Chinese individuals from the SMCSGES cohort. The phosphorylation levels of receptors and signaling proteins in the MAPK signaling cascades, including ErbB2, EGFR, and ERK1/2, were compared across the genotypes of asthma-associated SNPs through in vitro and ex vivo approaches., Results: The ERBB2 tag-SNP rs1058808 was significantly associated with allergic asthma, with the allele "G" identified as protective against the disease (adjusted logistic p = 6.56 × 10-9, OR = 0.625, 95% CI: 0.544-0.718). The allele "G" of rs1058808 resulted in a Pro1170Ala mutation that results in lower phosphorylation levels of ErbB2 in HaCat cells (p < 0.001), whereas the overall ERBB2 mRNA expression and the phosphorylation levels of EGFR remained unaffected. In the SMCSGES cohort, individuals carrying the genotype "GG" of rs1058808 had lower phosphorylated ERK1/2 proteins in the MAPK signaling cascade. A lower phosphorylation level of ERK1/2 was also associated with reduced asthma risk., Conclusions: The present findings highlighted the involvement of a functional exonic variant of ERBB2 in asthma development via modulating the MAPK signaling cascade., (© 2023 The Author(s). Published by S. Karger AG, Basel.)

The mitogen-activated protein kinase (MAPK) pathways are ubiquitous in cellular signaling and are essential for proper biological functions. Disruptions in this signaling axis can lead to diseases such as the development of cancer. In this review, we discuss members of the MAP3K family and correlate their mRNA expression levels to patient survival outcomes in different cancers. Furthermore, we highlight the importance of studying the MAP3K family due to their important roles in the larger, overall MAPK pathway, relationships with cancer progression, and the understudied status of these kinases., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s). Published by IMR Press.)

Inheritance of stable and euploid genomes is a prerequisite for species maintenance. The DNA damage response in germ cells controls the integrity of heritable genomes. Whether and how somatic stress responses impact the quality control of germline genomes has remained unclear. Here, we show that PMK-1/p38-mediated stress signaling in intestinal cells is required for germ cell apoptosis amid ionizing radiation (IR)-induced or meiotic DNA double strand breaks (DSBs) in C. elegans. We demonstrate that intestinal PMK-1/p38 signaling regulates the germ cell death in response to environmental stress. The PMK-1/p38 target SYSM-1 is secreted from the intestine into the germline to trigger apoptosis of meiotic pachytene cells. Compromised PMK-1/p38 signaling in intestinal cells leads to stress-induced aneuploidy in the consequent generation. Our data suggest that somatic stress surveillance controls heritable genome integrity and euploidy., (© 2022. The Author(s).)

Mitogen-activated protein kinase (MAPK) cascades are important signaling modules regulating diverse biological processes. During the past 20 years, much progress has been made on the functions of MAPK cascades in plants. This review summarizes the roles of MAPKs, known MAPK substrates, and our current understanding of MAPK cascades in plant development and innate immunity. In addition, recent findings on the molecular links connecting surface receptors to MAPK cascades and the mechanisms underlying MAPK signaling specificity are also discussed., (© 2022 The Authors.)

Mutational activation of the KRAS oncogene is found in ~95% of pancreatic ductal adenocarcinoma (PDAC), the major form of pancreatic cancer. With substantial experimental evidence that continued aberrant KRAS function is essential for the maintenance of PDAC tumorigenic growth, the National Cancer Institute has identified the development of effective anti-KRAS therapies as one of four major initiatives for pancreatic cancer research. The recent clinical success in the development of an anti-KRAS therapy targeting one specific KRAS mutant (G12C) supports the significant potential impact of anti-KRAS therapies. However, KRAS G12C mutations comprise only 2% of KRAS mutations in PDAC. Thus, there remains a dire need for additional therapeutic approaches for targeting the majority of KRAS-mutant PDAC. Among the different directions currently being pursued for anti-KRAS drug development, one of the most promising involves inhibitors of the key KRAS effector pathway, the three-tiered RAF-MEK-ERK mitogen-activated protein kinase (MAPK) cascade. We address the promises and challenges of targeting ERK MAPK signaling as an anti-KRAS therapy for PDAC. In particular, we also summarize the key role of the MYC transcription factor and oncoprotein in supporting ERK-dependent growth of KRAS-mutant PDAC., (Copyright © 2022 Elsevier Inc. All rights reserved.)

EpsteinBarr virus (EBV)-encoded latent membrane protein 1 (LMP1) plays an important oncogenic role in the viral latent infection. Recently, increasing evidence indicates that the high expression of LMP1 during EBV lytic cycle is related to the viral lytic replication. However, the mechanism by which LMP1 regulates EBV lytic replication remains unclear. ()-Epigallocatechin-3-gallate (EGCG) prevents carcinogenesis by directly targeting numerous membrane proteins and effectively inhibits EBV lytic cascade. Here, we demonstrated that LMP1 promotes EBV lytic replication through the downstream signal molecules MAPKs, including ERKs, p38, and JNKs. LMP1 induces the phosphorylation of p53 through MAPKs to enhance the ability of wild-type p53 (wt-p53) to activate expression of BZLF1 gene, while the JNKs/c-Jun signal axis appears to be involved in EBV lytic replication induced by LMP1 in p53 mutant manner. We provided the first evidence that EGCG directly targets the viral membrane LMP1 ( K d =0.36 M, n =1) using fluorescence quenching, isothermal titration calorimetry (ITC) assay, and CNBR-activated Sepharose 4B pull-down affinity chromatography. Furthermore, we revealed that EGCG inhibits EBV lytic replication via suppressing LMP1 and thus blocking the downstream MAPKs/wt-p53 signal axis in AGS-EBV cells and JNKs/c-Jun signal axis in p53 mutant B95.8 cells. Our study, for the first time, reports the binding and inhibitory efficacy of EGCG to the LMP1, which is a key oncoprotein encoded by EBV. These findings suggest the novel function of LMP1 in the regulation of EBV lytic cycle and reveal the new role of EGCG in EBV-associated malignancies through suppressing viral reactivation.

Microvascular changes and retinal degeneration precede diabetic retinopathy. Oxidative stress alters several intracellular signaling pathways, which form the basis of diabetic retinopathy. Many antioxidants have been investigated as possible preventive and therapeutic remedies for diabetic retinopathy. The current study investigated the modulatory effects of trans-resveratrol on streptozotocin-induced type 1 diabetes mediated changes in the transcription and levels of apoptosis-related proteins and mitogen-activated protein kinases (MAPKs) in the retinal pigment epithelium (RPE) of adult male dark Agouti rats. In control rats, 5 mg/kg/d trans-resveratrol administration for 30 days increased gene expressions of tumor suppressor protein 53, Bcl2-associated X protein, B-cell lymphoma-2 (Bcl2), Caspase-3 (CASP3), CASP8 and CASP9, p38αMAPK, c-Jun N-terminal kinase-1 (JNK1), and extracellular signal-regulated kinase-1 (ERK1). On the other hand, diabetes decreased gene expressions of CASP3, CASP8, p38αMAPK, JNK, and ERK1. Trans-resveratrol reversed the inhibited gene expressions of CASP8, p38αMAPK, JNK, and ERK1 to normal control levels in diabetic rats. Trans-resveratrol normalized diabetes-induced upregulation of CASP3 and -9, cytochrome-c, Bcl-2, and ERK1 proteins. In conclusion, Trans-resveratrol-induced alterations in gene expressions do not seem to affect RPE functions as they do not reflect as altered protein functions. Trans-resveratrol imparts its protective effects by normalizing apoptosis-related proteins and ERK1 but does not affect JNK proteins. Trans-resveratrol causes cytostasis in RPE of normal rats by upregulating Bcl2 protein and apoptotic proteins., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Some studies suggest that the inactivation of the Ras-MAPK pathway in trophoblast cells can lead to recurrent abortion, but the molecular mechanism underlying the inactivation of this pathway in trophoblast cells is still unclear. This study aimed to explore the relationship between the mechanism of abnormal activation of RASA1, a regulatory protein of the Ras-MAPK pathway, and unexplained recurrent spontaneous abortion. RT-qPCR was used to detect the transcription levels of RASA1 gene. Immunohistochemistry and Western blot were used to detect the expression levels of the RASA1, Raf and MEK proteins. CCK-8, TUNEL and Transwell assays were used to detect the proliferative, apoptotic, and invasive capacities of HTR-8/SVneo cells. ChIP assays were used to detect the enrichment of H3K27me3 in RASA1 gene promoter. Abortion villi experiments showed that the enrichment of H3K27me3 in the RASA1 gene promoter was reduced, and that both RASA1 gene transcription and RASA1 protein expression were increased. Cell experiments confirmed that RASA1 could decrease the phosphorylated Raf and MEK proteins, inhibit the proliferation and invasion ability, and promote the apoptosis ability of HTR-8/SVneo cells. It was also found that the proliferation and invasion ability as well as the Ras-MAPK pathway activity of HTR-8/SVneo cells were inhibited when treated with histone methyltransferase inhibitor DZNep. RASA1 gene was abnormally activated in unexplained recurrent spontaneous abortion villi due to the decreased enrichment of H3K27me3 in the gene promoter. High expression of RASA1 could inhibit the activity of the Ras-MAPK pathway, and thus inhibit the proliferation and invasion ability of trophoblast cells., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

A cascade formed by phosphorylation events of mitogen-activated protein kinases (MAPKs) takes part in plant stress responses. However, the roles of these MAPKs in resistance of potato (Solanum tuberosum) against Phytophthora pathogens is not well studied. Our previous work showed that a Phytophthora infestans RXLR effector targets and stabilizes the negative regulator of MAPK kinase 1 of potato (StMKK1). Because in Arabidopsis thaliana the AtMPK4 is the downstream phosphorylation target of AtMKK1, we performed a phylogenetic analysis and found that potato StMPK4/6/7 are closely related and are orthologs of AtMPK4/5/11/12. Overexpression of StMPK4/7 enhances plant resistance to P. infestans and P. parasitica. Yeast two-hybrid analysis revealed that StMPK7 interacts with StMKK1, and StMPK7 is phosphorylated on flg22 treatment and by expressing constitutively active StMKK1 (CA-StMKK1), indicating that StMPK7 is a direct downstream signalling partner of StMKK1. Overexpression of StMPK7 in potato enhances potato resistance to P. infestans. Constitutively active StMPK7 (CA-StMPK7; StMPK7 D198G, E202A ) was found to promote immunity to Phytophthora pathogens and to trigger host cell death when overexpressed in Nicotiana benthamiana leaves. Cell death triggered by CA-StMPK7 is SGT1/RAR1-dependent. Furthermore, cell death triggered by CA-StMPK7 is suppressed on coexpression with the salicylate hydroxylase NahG, and StMPK7 activation promotes salicylic acid (SA)-responsive gene expression. We conclude that potato StMPK7 is a downstream signalling component of the phosphorelay cascade involving StMKK1 and StMPK7 plays a role in immunity to Phytophthora pathogens via an SA-dependent signalling pathway., (© 2021 The Authors. Molecular Plant Pathology published by British Society for Plant Pathology and John Wiley & Sons Ltd.)

Pain is a major complication of cancer and significantly affects the quality of life. Cerebrospinal fluid-contacting nucleus (CSF-CN) has been reported to be involved in the development of neuropathic pain and inflammatory pain. However, whether CSF-CN contributes to cancer-induced bone pain (CIBP) remains unknown. In this study, we aimed to illustrate the role of CSF-CN in the pathogenesis of CIBP and identify its potential mechanism via the MKP-1-mediated MAPK pathway. The Walker 256 cancer cells were injected into the tibia cavity of female Sprague-Dawley rats to induce CIBP models. Intracerebroventricular injection of cholera toxin subunit B- saporin (CB-SAP) was performed to "knockout" the CSF-CN. Morphine and LV-MKP-1 were applied. Mechanical and thermal hyperalgesia behaviors, double immunofluorescence staining and Western blot were conducted after CIBP induction. The results revealed that CIBP significantly reduced the mechanical withdrawal threshold and the thermal threshold. Double immunofluorescence staining revealed that c-Fos-positive neurons in CSF-CN were significantly higher in the CIBP group than that in the sham group. Targeted ablation of CSF-CN dramatically aggravated pain sensitivity. Moreover, MKP-1 was down-regulated in the CSF-CN after CIBP induction. Pharmacological intervention with morphine significantly ameliorated the mechanical and thermal hyperalgesia through reversing the down-expression of MKP-1 in the CSF-CN on day 14 after CIBP induction. Mechanically, overexpression of MKP-1 by LV-MKP-1 injection significantly relieved CIBP via inhibiting the expression of phosphorylated p38, which subsequently decreased the protein levels of Bax, cleaved caspase-3 and Iba-1, and reduced the mRNA levels of IL-1β, TNF-α and IL-6 in CSF-CN. In conclusion, CSF-CN contributed to CIBP via regulating the MKP-1-mediated p38-MAPK pathway. Future therapy targeting the expression of MKP-1 in the CSF-CN may be a promising new choice., Competing Interests: Declaration of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Cell cycle is essential for the maintenance of genetic material and continuity of a species. Its regulation involves a complex interplay between multiple proteins with diverse molecular functions such as the kinases, transcription factors, proteases and phosphatases. Every step of this cycle requires a certain combination of these protein regulators which paves the way for the next stage. It is now evident that plants have their own unique features in the context of cell cycle regulation. Cell cycle in plants is not only necessary for maintenance of its physio-morphological parameter but it also regulates traits important for mankind like grain or fruit size. This makes it even more important to understand how plants regulate its cell cycle amidst various a/biotic stresses it is subjected to during its lifetime. The association of MAPK signaling pathways with every major developmental and stress response pathways in plants raises the question of its potential role in cell cycle regulation. There are number of cell cycle regulating proteins with putative sites for MAPK phosphorylation. The MAPK signaling pathway may directly or in a parallel pathway regulate the plant cell cycle. Unraveling the role of MAPK in cell cycle will open up new arenas to explore., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Aberrantly activated kinase signaling pathways drive invasion and dissemination in medulloblastoma (MB). A majority of tumor-promoting kinase signaling pathways feed into the mitogen-activated protein kinase (MAPK) extracellular regulated kinase (ERK1/2) pathway. The activation status of ERK1/2 during invasion of MB cells is not known and its implication in invasion control unclear. We established a synthetic kinase activation relocation sensor (SKARS) for the MAPK ERK1/2 pathway in MB cells for real-time measuring of drug response. We used 3D invasion assays and organotypic cerebellum slice culture to test drug effects in a physiologically relevant tissue environment. We found that hepatocyte growth factor (HGF), epidermal growth factor (EGF), or basic fibroblast growth factor (bFGF) caused rapid nuclear ERK1/2 activation in MB cells, which persisted for several hours. Concomitant treatment with the BCR/ABL kinase inhibitor dasatinib completely repressed nuclear ERK1/2 activity induced by HGF and EGF but not by bFGF. Increased nuclear ERK1/2 activity correlated positively with speed of invasion. Dasatinib blocked ERK-associated invasion in the majority of cells, but we also observed fast-invading cells with low ERK1/2 activity. These ERK1/2-low, fast-moving cells displayed a rounded morphology, while ERK-high fast-moving cells displayed a mesenchymal morphology. Dasatinib effectively blocked EGF-induced proliferation while it only moderately repressed tissue invasion, indicating that a subset of cells may evade invasion repression by dasatinib through non-mesenchymal motility. Thus, growth factor-induced nuclear activation of ERK1/2 is associated with mesenchymal motility and proliferation in MB cells and can be blocked with the BCR/ABL kinase inhibitor dasatinib., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

A large fraction of human cancers contain genetic alterations within the Mitogen Activated Protein Kinase (MAPK) signaling network that promote unpredictable phenotypes. Previous studies have shown that the temporal patterns of MAPK activity (i.e. signaling dynamics) differentially regulate cell behavior. However, the role of signaling dynamics in mediating the effects of cancer driving mutations has not been systematically explored. Here, we show that oncogene expression leads to either pulsatile or sustained ERK activity that correlate with opposing cellular behaviors (i.e. proliferation vs. cell cycle arrest, respectively). Moreover, sustained-but not pulsatile-ERK activity triggers ERK activity waves in unperturbed neighboring cells that depend on the membrane metalloprotease ADAM17 and EGFR activity. Interestingly, the ADAM17-EGFR signaling axis coordinates neighboring cell migration toward oncogenic cells and is required for oncogenic cell extrusion. Overall, our data suggests that the temporal patterns of MAPK activity differentially regulate cell autonomous and non-cell autonomous effects of oncogene expression., Competing Interests: TA, AP, MP, HC, SR No competing interests declared, (© 2020, Aikin et al.)

Background: Mitogen Activated Protein Kinase (MAPK) cascade is a fundamental pathway in organisms for signal transduction. Though it is well characterized in various plants, there is no systematic study of this cascade in tea., Result: In this study, 5 genes of Mitogen Activated Protein Kinase Kinase (MKK) and 16 genes of Mitogen Activated Protein Kinase (MPK) in Camellia sinensis were found through a genome-wide search taking Arabidopsis thaliana as the reference genome. Also, phylogenetic relationships along with structural analysis which includes gene structure, location as well as protein conserved motifs and domains, were systematically examined and further, predictions were validated by the results. The plant species taken for comparative study clearly displayed segmental duplication, which was a significant candidate for MAPK cascade expansion. Also, functional interaction was carried out in C. sinensis based on the orthologous genes in Arabidopsis. The expression profiles linked to various stress treatments revealed wide involvement of MAPK and MAPKK genes from Tea in response to various abiotic factors. In addition, the expression of these genes was analysed in various tissues., Conclusion: This study provides the targets for further comprehensive identification, functional study, and also contributed for a better understanding of the MAPK cascade regulatory network in C. sinensis.

Mitogen-activated protein kinases (MAPKs) are key regulators of numerous biological processes in plants. To better understand the mechanisms by which these kinases function, high resolution measurement of MAPK activation kinetics in different biological contexts would be beneficial. One method to measure MAPK activation in plants is via fluorescence-based genetically-encoded biosensors, which can provide real-time readouts of the temporal and spatial dynamics of kinase activation in living tissue. Although fluorescent biosensors have been widely used to study MAPK dynamics in animal cells, there is currently only one MAPK biosensor that has been described for use in plants. To facilitate creation of additional plant-specific MAPK fluorescent biosensors, we report the development of two new tools: an in vitro assay for efficiently characterizing MAPK docking domains and a translocation-based kinase biosensor for use in plants. The implementation of these two methods has allowed us to expand the available pool of plant MAPK biosensors, while also providing a means to generate more specific and selective MAPK biosensors in the future. Biosensors developed using these methods have the potential to enhance our understanding of the roles MAPKs play in diverse plant signaling networks affecting growth, development, and stress response.

Cellular processes are inherently noisy, and the selection for accurate responses in presence of noise has likely shaped signalling networks. Here, we investigate the trade-off between accuracy of information transmission and its energetic cost for a mitogen-activated protein kinase (MAPK) signalling cascade. Our analysis of the pheromone response pathway of budding yeast suggests that dose-dependent induction of the negative transcriptional feedbacks in this network maximizes the information per unit energetic cost, rather than the information transmission capacity itself. We further demonstrate that futile cycling of MAPK phosphorylation and dephosphorylation has a measurable effect on growth fitness, with energy dissipation within the signalling cascade thus likely being subject to evolutionary selection. Considering optimization of accuracy versus the energetic cost of information processing, a concept well established in physics and engineering, may thus offer a general framework to understand the regulatory design of cellular signalling systems.

Mitogen-activated protein kinase (MAPK) is a form of serine/threonine protein kinase that activated by extracellular stimulation acting through the MAPK cascade (MAPKKK-MAPKK-MAPK). The MAPK cascade gene family, an important family of protein kinases, plays a vital role in responding to various stresses and hormone signal transduction processes in plants. In this study, we identified 14 CmMAPKs, 6 CmMAPKKs and 64 CmMAPKKKs in melon genome. Based on structural characteristics and a comparison of phylogenetic relationships of MAPK gene families from Arabidopsis, cucumber and watermelon, CmMAPKs and CmMAPKKs were categorized into 4 groups, and CmMAPKKKs were categorized into 3 groups. Furthermore, chromosome location revealed an unevenly distribution on chromosomes of MAPK cascade genes in melon, respectively. Eventually, qRT-PCR analysis showed that all 14 CmMAPKs had different expression patterns under drought, salt, salicylic acid (SA), methyl jasmonate (MeJA), red light (RL), and Podosphaera xanthii (P. xanthii) treatments. Overall, the expression levels of CmMAPK3 and CmMAPK7 under different treatments were higher than those in control. Our study provides an important basis for future functional verification of MAPK genes in regulating responses to stress and signal substance in melon., Competing Interests: The authors have declared that no competing interests exist.

The mitogen activated protein kinases (MAPKs) form part of a signaling cascade through phosphorylation reactions conserved in all eukaryotic organisms. The MAPK cascades are mainly composed by three proteins, MAPKKKs, MAPKKs and MAPKs. Some signals induce MAPKKK-mediated phosphorylation and activation of MAPKK that phosphorylate and activate MAPK. Afterward, MAPKs can act either in the cytoplasm or be imported into the nucleus to activate other proteins or transcription factors. In the green microalga Chlamydomonas reinhardtii the pathway for nitrogen (N) assimilation is well characterized, yet its regulation still has many unknown features. Nitric oxide (NO) is a fundamental signal molecule for N regulation, where nitrate reductase (NR) plays a central role in its synthesis. The MAPK cascades could be regulating N assimilation, since it has been described that the phosphorylation of NR by MAPK6 promotes NO production in Arabidopsis thaliana . We have identified the proteins involved in the MAPK cascades in Chlamydomonas reinhardtii , finding 17 MAPKs, 2 MAPKKs and 108 MAPKKKs (11 MEKK-, 94 RAF- and 3 ZIK-type) that have been structurally and phylogenetically characterized. The genetic expressions of MAPKs and the MAPKK were slightly regulated by N. However, the genetic expressions of MAPKKKs RAF14 and RAF79 showed a very strong repression by ammonium, which suggests that they may have a key role in the regulation of N assimilation, encouraging to further analyze in detail the role of MAPK cascades in the regulation of N metabolism.

The MAP kinase (MAPK) Hog1 is the central regulator of osmoadaptation in yeast. When cells are exposed to high osmolarity, the functionally redundant Sho1 and Sln1 osmosensors, respectively, activate the Ste11-Pbs2-Hog1 MAPK cascade and the Ssk2/Ssk22-Pbs2-Hog1 MAPK cascade. In a canonical MAPK cascade, a MAPK kinase kinase (MAP3K) activates a MAPK kinase (MAP2K) by phosphorylating two conserved Ser/Thr residues in the activation loop. Here, we report that the MAP3K Ste11 phosphorylates only one activating phosphorylation site (Thr-518) in Pbs2, whereas the MAP3Ks Ssk2/Ssk22 can phosphorylate both Ser-514 and Thr-518 under optimal osmostress conditions. Mono-phosphorylated Pbs2 cannot phosphorylate Hog1 unless the reaction between Pbs2 and Hog1 is enhanced by osmostress. The lack of the osmotic enhancement of the Pbs2-Hog1 reaction suppresses Hog1 activation by basal MAP3K activities and prevents pheromone-to-Hog1 crosstalk in the absence of osmostress. We also report that the rapid-and-transient Hog1 activation kinetics at mildly high osmolarities and the slow and prolonged activation kinetics at severely high osmolarities are both caused by a common feedback mechanism., (© 2020 The Authors. Published under the terms of the CC BY 4.0 license.)

Cell-autonomous changes in p53 expression govern the duration and outcome of cell-cycle arrest at the G2 checkpoint for DNA damage. Here, we report that mitogen-activated protein kinase (MAPK) signaling integrates extracellular cues with p53 dynamics to determine cell fate at the G2 checkpoint. Optogenetic tools and quantitative cell biochemistry reveal transient oscillations in MAPK activity dependent on ataxia-telangiectasia-mutated kinase after DNA damage. MAPK inhibition alters p53 dynamics and p53-dependent gene expression after checkpoint enforcement, prolonging G2 arrest. In contrast, sustained MAPK signaling induces the phosphorylation of CDC25C, and consequently, the accumulation of pro-mitotic kinases, thereby relaxing checkpoint stringency and permitting cells to evade prolonged G2 arrest and senescence induction. We propose a model in which this MAPK-mediated mechanism integrates extracellular cues with cell-autonomous p53-mediated signals, to safeguard genomic integrity during tissue proliferation. Early steps in oncogene-driven carcinogenesis may imbalance this tumor-suppressive mechanism to trigger genome instability., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Bronchopulmonary dysplasia (BPD), also known as neonatal chronic lung disease, is an important cause of respiratory illness in preterm newborns that results in significant morbidity and mortality. Long noncoding RNAs (lncRNAs) have been discovered with many biological functions. However, the role of lncRNAs in the pathogenesis of BPD remains poorly understood. Here, we established a mouse lung injury model that mimicked human BPD. Subsequently, we found the lncRNA H19 expression level was significantly increased in BPD compared with normal lung tissues using quantitative real-time polymerase chain reaction. Next, we observed that overexpression of lncRNA H19 enhanced mitogen-activated protein kinase (MAPK) signaling pathway. In addition, we also found that dysfunction of lncRNA H19 altered the expression of inflammatory factors. Thus, our study validates that lncRNA H19 contributes to the progression of BPD by regulating MAPK signaling pathway, which could be used as a potential target for treating BPD.

The regulatory roles of mitogen-activated protein kinase (MAPK) signaling pathways on the hypothalamic-pituitary-gonadal axis (HPG axis) of Wenchang chicks under heat stress (HS) were investigated. Additionally, the crosstalk between these signaling pathways was explored. Immunohistochemical experiments and Western blotting were employed to quantify extracellular regulated protein kinases (ERK), c-Jun N-terminal kinases (JNK), and p38MAPK (P38). In female chicks, hypothalamic ERKs were upregulated in Weeks 1 and 2 in the HS group compared with the control group (CK), while JNK and p38 were downregulated (P < 0.05). Pituitary MAPKs were all downregulated in the HS group compared with the CK group in Week 3, but p38 was upregulated in Week 4 (P < 0.01). In the HS group, ovarian MAPKs were all upregulated compared with the CK group during Week 5, whereas ERK was downregulated in Week 6 (P < 0.01). In contrast to the patterns of MAPK expression in female chicks in the HS and CK groups, ERK in male chicks showed a completely opposite pattern in Weeks 1, 2, and 5, while p38 and JNK were downregulated in both female and male chicks under HS during Weeks 2 and 3. In the HS group, pituitary and testis MAPKs showed a pattern opposite to that observed in female chicks under HS in Week 5; MAPKs were all downregulated (P < 0.05). Thus, there are gender differences in the MAPK signaling pathways in the HPG axis in chicks, and these pathways showed plasticity. Early HS can enhance chick growth and development as well as promote developing in the MAPK signaling pathways in the HPG axis. However, after heated brooding was discontinued in chicks, long-term HS obstructed chick development and caused tissue and function injury to the HPG axis., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)

Optogenetic approaches are transforming quantitative studies of cell-signaling systems. A recently developed photoswitchable mitogen-activated protein kinase kinase 1 (MEK1) enzyme (psMEK) short-circuits the highly conserved Extracellular Signal-Regulated Kinase (ERK)-signaling cascade at the most proximal step of effector kinase activation. However, since this optogenetic tool relies on phosphorylation-mimicking substitutions in the activation loop of MEK, its catalytic activity is predicted to be substantially lower than that of wild-type MEK that has been phosphorylated at these residues. Here, we present evidence that psMEK indeed has suboptimal functionality in vivo and propose a strategy to circumvent this limitation by harnessing gain-of-function, destabilizing mutations in MEK. Specifically, we demonstrate that combining phosphomimetic mutations with additional mutations in MEK, chosen for their activating potential, restores maximal kinase activity in vitro. We establish that this modification can be tuned by the choice of the destabilizing mutation and does not interfere with reversible activation of psMEK in vivo in both Drosophila and zebrafish. To illustrate the types of perturbations enabled by optimized psMEK, we use it to deliver pulses of ERK activation during zebrafish embryogenesis, revealing rheostat-like responses of an ERK-dependent morphogenetic event., Competing Interests: The authors declare no competing interest.

The yeast stress-activated protein kinase Hog1 is best known for its role in mediating the response to osmotic stress, but it is also activated by various mechanistically distinct environmental stressors, including heat shock, endoplasmic reticulum stress, and arsenic. In the osmotic stress response, the signal is sensed upstream and relayed to Hog1 through a kinase cascade. Here, we identified a mode of Hog1 function whereby Hog1 senses arsenic through a direct physical interaction that requires three conserved cysteine residues located adjacent to the catalytic loop. These residues were essential for Hog1-mediated protection against arsenic, were dispensable for the response to osmotic stress, and promoted the nuclear localization of Hog1 upon exposure of cells to arsenic. Hog1 promoted arsenic detoxification by stimulating phosphorylation of the transcription factor Yap8, promoting Yap8 nuclear localization, and stimulating the transcription of the only known Yap8 targets, ARR2 and ARR3 , both of which encode proteins that promote arsenic efflux. The related human kinases ERK1 and ERK2 also bound to arsenic in vitro, suggesting that this may be a conserved feature of some members of the mitogen-activated protein kinase (MAPK) family. These data provide a mechanistic basis for understanding how stress-activated kinases can sense distinct threats and perform highly specific adaptive responses., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Background: We previously showed that cobalt chloride (CoCl 2 ) induction of polyploid giant cancer cells (PGCCs) was characterized by abnormal cell cycle-related protein expression and G2/M arrest. The role of the p38MAPK-ERK-JNK signaling pathway in cell cycle regulation has been reported, but the mechanism by which p38MAPK-ERK-JNK regulates PGCCs formation remains unclear. This study examined p38MAPK-ERK-JNK-CDC25C expression in PGCCs and their daughter and control cells and assessed the clinicopathological significance of p38MAPK, ERK, JNK, and CDC25C expression in human ovarian and breast cancers., Methods: CoCl 2 was used to induce the formation of PGCCs in HEY and BT-549 cells. Western blotting and immunocytochemical staining were used to compare the expression and subcellular localization of p38MAPK, ERK, JNK, and CDC25C in the control group and CDC25C knockdown before and after CoCl 2 treatment. The specific combination of p38MAPK and ERK with pCDC25C-Ser216 was detected by immunoprecipitation. In addition, p38MAPK, ERK, JNK, and CDC25C immunohistochemical staining were performed to compare the clinicopathologic significances in 81 cases of ovarian cancer tissue, including 20 cases of primary breast cancer with lymph node metastasis (group I), and their corresponding metastatic lymph nodes (group II), 31 cases of primary breast cancer without metastasis (group III), and 10 cases of benign breast tumors (group IV). Breast tumor tissue from 229 was divided into two groups: 167 cases of primary invasive breast cancer (group 1) and 62 cases of lymph node metastatic breast cancer (group 2)., Results: Compared to the control cells, p38MAPK and JNK expression were higher and CDC25C expression was lower in CoCl 2 -treated cells. Moreover, ERK displayed a trend of increased expression in HEY PGCCs and decreased expression in BT-549 PGCCs. p38MAPK and ERK regulated CDC25C by phosphorylating the CDC25C-Ser216 site and participated in the G2/M phase transition. Immunohistochemical (IHC) analysis of the ovarian tumor tissues showed significant positive staining rates of p38MAPK (P = 0.001), ERK (P = 0.002), JNK (P = 0.000), and CDC25C (P = 0.000) among the four groups. In breast tumor tissues, the overall expression in p38MAPK (P = 0.029), ERK (P = 0.002), JNK (P = 0.013), and CDC25C (P = 0.001) also differed significantly between the two groups., Conclusion: The p38MAPK-ERK-JNK signaling pathway was involved in cell cycle progression and the formation of PGCCs by regulation of CDC25C.

Phosphatidic acid (PA) is a lipid secondary messenger involved in intracellular signaling in eukaryotes. It has been confirmed that PA mediates salt stress signaling by promoting activation of Mitogen-activated Protein Kinase 6 (MPK6) which phosphorylates Na + /H + antiporter SOS1. However, the MPK6-upstream kinases and their relationship to PA remain unclear. Here, we found that, among the six tested Arabidopsis Mitogen-activated Protein Kinase Kinases (MKKs), PA specifically bound to MKK7 and MKK9 which phosphorylate MPK6, and promoted the activation of MKK7/MKK9. Based on phenotypic and physiological analyses, we found that MKK7 and MKK9 positively regulate Arabidopsis salt tolerance and are functionally redundant. NaCl treatment can induce significant increase in MKK7/MKK9 activities, and this depends, in part, on the Phospholipase Dα1 (PLDα1). MKK7 and MKK9 also mediate the NaCl-induced activation of MPK6. Furthermore, PA or NaCl treatment could induce translocation of MKK7/MKK9 to the plasma membrane, whereas this translocation disappeared in pldα1. These results indicate that PA binds to MKK7 and MKK9, increases their kinase activity and plasma membrane localization during Arabidopsis response to salt stress. Together with the PA-MPK6-SOS1 pathway identified previously, this mechanism may maximize the signal transduction efficiency, providing novel insights into the link between lipid signaling and MAPK cascade., (Copyright © 2019. Published by Elsevier B.V.)

Cucurbitacin IIa (CuIIa), a tetracyclic triterpenoid harboring anticancer activity, was investigated in A549 cells to reveal its mechanism of targeting on epidermal growth factor receptor (EGFR) signaling pathway. Results showed that CuIIa was capable of inducing apoptosis and cell cycle arrest at G2/M phase. The transcription of EGFR pathway genes and their proteins accumulation was inconsistently influenced by CuIIa. Notably, transcription of Raf1 was significantly upregulated, nevertheless, MEK1 and ERK1 were significantly downregulated. On the other hand, the accumulation of the total and phosphorylated proteins of the most members in EGFR-mitogen-activated protein kinase (MAPK) pathway, as well as CylclinB1 and survivin were also shifted by CuIIa treatment. Remarkably, total MEK remained constant but survivin completely degraded. Moreover, phosphorylated BRAF continuously increased while Raf1 and MEK decreased continuously. CuIIa was further confirmed to be a tyrosine kinase inhibitor (TKI) of EGFR by kinase inhibition assay. The results of molecular simulation showed that the long side chain of CuIIa occupied the binding pocket of EGFR and the ligand was stabilized at the active site of EGFR. In view of the results above, it is suggested that CuIIa inhibits cell proliferation by interfering the EGFR-MAPK signaling pathway., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The mating-specific yeast Gα controls pheromone signaling by sequestering Gβγ and by regulating the Fus3 MAP kinase. Disrupting Gα-Fus3 interaction leads to severe defects in chemotropism. Because Gα concentrates at the chemotropic growth site where Fus3 is required for the phosphorylation of two known targets, we screened for additional proteins whose phosphorylation depends on pheromone stimulation and Gα-Fus3 interaction. Using a mutant form of Gα severely defective in Fus3-binding, Gα DSD , and quantitative mass spectrometry, fourteen proteins were identified as potential targets of Gα-recruited Fus3, ten of which were previously implicated in cell polarity and morphogenesis. To explore the biological relevance of these findings, we focused on the Spa2 polarisome protein, which was hypophosphorylated on multiple serine residues in pheromone-treated Gα DSD cells. Six sites were mutagenized to create the Spa2 6XSA mutant protein. Spa2 6XSA exhibited increased affinity for Fus3, consistent with a kinase-substrate interaction, and Spa2 6XSA cells exhibited dramatic defects in gradient sensing and zygote formation. These results suggest that Gα promotes the phosphorylation of Spa2 by Fus3 at the cortex of pheromone-stimulated cells, and that this mechanism plays a role in chemotropism. How the Gα-Fus3 signaling hub affects the other putative targets identified here has yet to be determined. SIGNIFICANCE: Previously, interaction between the G alpha protein, Gpa1, and the MAPK of the pheromone response pathway, Fus3, was shown to be important for efficient sensing of the pheromone gradient and for the maintenance of cell polarity during mating. Here we show that the underlying molecular mechanisms involve the phosphorylation of specific cortical targets of Gpa1/Fus3. These have been identified by quantitative phosphoproteomics using a mutant of Gpa1, which is defective in interacting with Fus3. One of these targets is the polarisome protein Spa2. Alanine substitution of the Spa2 phosphorylation sites targeted by Gpa1/Fus3 lead to a dramatic defect in pheromone gradient sensing and zygote formation. These results reveal how the G alpha protein and the MAPK control cell polarity in a prototypical model system. Our results have wider significance as similar mechanisms exist in higher eukaryotes and are involved in important biological such as neuron development, immunity, and cancer cell metastasis., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objective: To detect phosphorylated-extracellular signal-regulated kinase (p-ERK1/2) protein expression in epithelial ovarian cancer and cell lines, and to examine the effects of mitogen-activated protein kinase (MAPK) kinase (MEK) inhibitor AZD6244 on cell proliferation, apoptosis as well as cell cycle of ovarian cancer cells. To explore the function and significance of MAPK/extracellular signal-regulated kinase (ERK) signaling pathway in the development of ovarian cancer. Methods: (1) A total of 104 cases of patients with ovarian cancer who accepted the treatment of gynecological surgery and being confirmed by pathological examination in First Affiliated Hospital, Dalian Medical University from January 2004 to December 2013 were selected. The expressions of p-ERK1/2 protein were detected by immunohistochemistry in ovarian cancer specimens, and the relationship between the expressions of p-ERK1/2 and the clinical features of patients was analyzed. (2) p-ERK1/2 and other related proteins were determined by western blot in various ovarian cancer cells, including SKOV3, OV2008, C13, A2780S, A2780CP, OVCAR4, OVCAR5, OVCAR8 and CAOV3 treated with or without MEK inhibitor. The cellular proliferation, apoptosis and cell cycle of ovarian cancer cells after treatment with MEK inhibitor were analyzed by methyl thiazolyl tetrazolium (MTT) assay and flow cytometry, respectively. Results: (1) The immunohistochemical method showed that p-ERK1/2 between low grade serous carcinoma and clear cell carcinoma were not significantly higher expressed ( P >0.05) . However, a lower level of the p-ERK1/2 expression were observed among high grade serous carcinoma, mucinous carcinoma and endometrioid carcinoma (all P <0.05) . There was no significant correlation between the protein expression of p-ERK1/2 and patients' age, pathological stage of surgery, and preoperative serum CA(125) level ( P >0.05). (2) Western blot showed that the protein p-ERK1/2 was widely expressed in various ovarian cancer cell lines such as SKOV3, OV2008, C13, A2780S, A2780CP, OVCAR4, OVCAR5, OVCAR8 and CAOV3. After treatment with AZD6244 (5, 10 μmol/L), the level of p-ERK1/2 in OVCAR5 and OVCAR8 decreased significantly in dose-dependent manner. Additionally, we found a reduction of the expression level of cyclin D1, caspase-3 and appeared cleaved poly adenosine diphosphate ribose polymerase (PARP) in OVCAR5 and OVCAR8, compared with control groups. MTT assays showed that OVCAR5, OVCAR8 and A2780S were differently inhibited in the dose-dependent manner after being treated with different concentrations of AZD6244 (0, 2.5, 5, 10, 25, 50 and 100 μmol/L, all P <0.05). Further tested by flow cytometry, the results showed that AZD6244 (5, 10 μmol/L) was able to induce the apoptosis of OVCAR5, OVCAR8 and A2780S, as well as G(0)/G(1) phase arrest, both in a dose-dependent manner ( P <0.05). Conclusions: As the main active and functional unit of MAPK/ERK signaling pathway, p-ERK1/2 protein is expressed in both the tissues and various ovarian cancer cell lines. AZD6244 could down-regulated the expression of p-ERK1/2 in ovarian cancer cells, accompanied by the decreased proliferation and increased cell apoptosis of ovarian cancer cells. In conclusion, MAPK/ERK signaling pathway might play a role in the development and progression of ovarian cancer, and may be provide a novel option for molecular targeted therapies of the disease.

This study primarily explored how miR-145, mitogen-activated protein kinase (MAPK) signaling and a downstream transcription factor (i.e., SOX9) mediated development of hypospadias. The hypospadias tissues and preputial tissues were isolated from pediatric inpatients postoperatively. Simultaneously, the rat models of hypospadias were established, and spermatogonial stem cells were separated. The expressions of proteins that symbolized cell apoptosis and oxidative stress were quantified via western blot analysis. Furthermore, the apoptosis, proliferation, and viability of cells were evaluated by means of flow cytometry, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation assays. The results of microarray indicated miR-145 as a differentially expressed biomarker between hypospadias tissues and normal tissues (p < 0.05). Moreover, rat models of hypospadias were observed with markedly lower vitamins A and E levels, reduced expressions of proteins relevant to oxidative stress (i.e., Nrf2, HO-1, Gpx, and SOD-1), as well as enhanced Bax and cleaved caspase-3 expressions ( p < 0.05). Furthermore, SOX9 was found to be targeted by miR-145, and it was also modified by phosphorylated extracellular-regulated kinase (p-ERK), a portion of MAPK signaling ( p < 0.05). The p-ERK was significantly regulated after altering the expression of miR-145 ( p < 0.05). Moreover, activation of p-ERK and transfection of pcDNA-SOX9 could cause higher expression of apoptins and larger apoptotic proportion of cells ( p < 0.05), yet transfection of miR-145 mimic led to improved cell apoptosis and depressed cell viability ( p < 0.05). In conclusion, SOX9, which was regulated by both miR-145 and miR-145/MAPK signaling, could be involved in the pathogenesis of hypospadias., (© 2018 Wiley Periodicals, Inc.)

ERK1 and ERK2 (ERKs), two extracellular regulated kinases (ERK1/2), are evolutionary-conserved and ubiquitous serine-threonine kinases involved in regulating cell signalling in normal and pathological tissues. The expression levels of these kinases are almost always different, with ERK2 being the more prominent. ERK1/2 activation is fundamental for the development and progression of cancer. Since their discovery, much research has been dedicated to their role in mitogen-activated protein kinases (MAPK) pathway signalling and in their activation by mitogens and mutated RAF or RAS in cancer cells. In order to gain a better understanding of the role of ERK1/2 in MAPK pathway signalling, many studies have been aimed at characterizing ERK1/2 splicing isoforms, mutants, substrates and partners. In this review, we highlight the differences between ERK1 and ERK2 without completely discarding the hypothesis that ERK1 and ERK2 exhibit functional redundancy. The main goal of this review is to shed light on the role of ERK1/2 in targeted therapy and radiotherapy and highlight the importance of identifying ERK inhibitors that may overcome acquired resistance. This is a highly relevant therapeutic issue that needs to be addressed to combat tumours that rely on constitutively active RAF and RAS mutants and the MAPK pathway.

With the introduction of arsenic trioxide and all-trans retinoic acid, the prognosis of acute promyelocytic leukemia has greatly improved. However, all-trans retinoic acid resistance is still unresolved in acute promyelocytic leukemia relapsed patients. In this study, the clinical achievable concentration of 7-hydroxystaurosporine synergized with all-trans retinoic acid to induce terminal differentiation in all-trans retinoic acid resistant acute promyelocytic leukemia cell lines. Though 7-hydroxystaurosporine is a PKC inhibitor, PKC might not be involved in the combination-induced differentiation since other PKC selective inhibitors, Gö 6976 and rottlerin failed to cooperate with all-trans retinoic acid to trigger differentiation. The combination significantly enhanced the protein level of CCAAT/enhancer binding protein β and/or PU.1 as well as activated MEK/ERK. U0126 (MEK specific inhibitor) not only suppressed the combination-induced differentiation but also restored the protein level of CCAAT/enhancer binding protein β and/or PU.1. However, RAF-1 inhibitor had no inhibitory effect on MEK activation and the combination-induced differentiation. Therefore, the combination overcame differentiation block via RAF-1 independent MEK/ERK modulation of the protein level of CCAAT/enhancer binding protein β and/or PU.1. These findings may provide a preclinical rationale for the potential role of this combination in the treatment of all-trans retinoic acid resistant acute promyelocytic leukemia patients., (Copyright © 2019. Published by Elsevier Ltd.)

Fungi have three mitogen-activated protein kinases (MAPKs): Kss1/Fus3 involved in the invasive growth and virulence of pathogens, Hog1 in response to osmotic stress, and Slt2/Mpk1 in response to cell wall (CW) stress. We conducted comparative analyses of these MAPKs in the phytopathogen Penicillium digitatum and studied their role in the mode of action of the novel self-antifungal protein AfpB. The sensitivity to different stresses of Δhog1 and the reduced growth of Δkss1 coincided with previous reports. However, Δslt2 showed a strong reduction of growth and conidiation, abnormal morphology, and sensitivity to CW stress and temperature. The complementation of Δslt2 validated this mutant. Immunodetection of P-Hog1 and P-Slt2 confirmed the loss and gain of MAPKs in the mutant and complemented strains. Mutants Δslt2 and Δkss1 showed a strong reduction in virulence, whereas Δhog1 was the least affected, and none sporulated during infection. We studied the MAPK signalling induction in response to different treatments. Our data revealed a complex crosstalk involving the three MAPKs, the differential responses of Hog1 and Slt2 to various stresses and their induction by AfpB or the fungicide fludioxonil (FD). Δhog1 resistance to FD confirmed that Hog1 mediates the activity of FD, whereas Δkss1 sensitivity is probably due to the basal activation of Hog1 in Δkss1. None of the three MAPK mutants showed increased sensitivity to AfpB, contrary to previous reports of other antifungal proteins, which indicates that the observed AfpB-mediated activation of Hog1 and Slt2 would not have a defensive role., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The catalytic activity of mitogen-activated protein kinases (MAPKs) is dynamically modified in plants. Since MAPKs have been shown to play important roles in a wide range of signaling pathways, the ability to monitor MAPK activity in living plant cells would be valuable. Here, we report the development of a genetically encoded MAPK activity sensor for use in Arabidopsis thaliana. The sensor is composed of yellow and blue fluorescent proteins, a phosphopeptide binding domain, a MAPK substrate domain and a flexible linker. Using in vitro testing, we demonstrated that phosphorylation causes an increase in the Förster resonance energy transfer (FRET) efficiency of the sensor. The FRET efficiency can therefore serve as a readout of kinase activity. We also produced transgenic Arabidopsis lines expressing this sensor of MAPK activity (SOMA) and performed live-cell imaging experiments using detached cotyledons. Treatment with NaCl, the synthetic flagellin peptide flg22 and chitin all led to rapid gains in FRET efficiency. Control lines expressing a version of SOMA in which the phosphosite was mutated to an alanine did not show any substantial changes in FRET. We also expressed the sensor in a conditional loss-of-function double-mutant line for the Arabidopsis MAPK genes MPK3 and MPK6. These experiments demonstrated that MPK3/6 are necessary for the NaCl-induced FRET gain of the sensor, while other MAPKs are probably contributing to the chitin and flg22-induced increases in FRET. Taken together, our results suggest that SOMA is able to dynamically report MAPK activity in living plant cells., (© 2018 The Authors The Plant Journal © 2018 John Wiley & Sons Ltd.)

BRAFV600E is a mutant Ser-Thr protein kinase that plays a crucial role in many types of cancer, including melanoma. Despite several aspects of BRAFV600E biology have been already elucidated, the proteins that regulate its expression and activity remain largely unknown, hampering our capacity to control its unrestrained effects. Here, we propose yeast Saccharomyces cerevisiae as a model system that can be used to achieve a better understanding of the regulation of human BRAFV600E.By showing that in osmotic stress conditions hBRAFV600E can rescue the growth of strains carrying a double or triple deletion in MAPKKK belonging to the HOG pathway, we demonstrate that this oncogenic kinase is active in yeast even if it does not have an ortholog. Moreover, we report that, in the yeast ptp3∆ptc1∆ strain that is deleted in the genes encoding for two phosphatases responsible for Hog1 de-phoshorylation, hBRAFV600E mimics the toxicity observed in the presence of constitutive Hog1 activation. Finally, we exploit such a toxicity to perform a functional screening of a human cDNA library, looking for cDNAs able to rescue yeast growth. In this way, we identify SMIM10, a mitochondrial protein that in melanoma cells selectively downregulates BRAFV600E RNA and protein levels, by acting indirectly at the post-transcriptional level. Upon SMIM10 overexpression, BRAFV600E melanoma cells show disrupted mitochondrial structure/function and undergo senescence. They also show decreased ability to proliferate and form colonies, as well as increased sensitivity to the BRAF inhibitor vemurafenib. Interestingly, the analysis of TCGA melanoma samples indicates that patients with higher SMIM10 levels have a better prognosis. Therefore, these data suggest that SMIM10 exerts an oncosuppressive role in melanoma cells.Taken together, our results unveil the potential of S. cerevisiae to study hBRAFV600E, to populate the network of its functional interactors and, in doing so, to uncover new cancer-associated genes with therapeutic potential.

Osteoarthritis (OA) is a degenerative disease characterized by progressive articular cartilage destruction and joint marginal osteophyte formation with different degrees of synovitis. Docosahexaenoic acid (DHA) is an unsaturated fatty acid with anti-inflammatory, antioxidant, and antiapoptotic functions. In this study, the human chondrosarcoma cell line SW1353 was cultured in vitro, and an OA cell model was constructed with inflammatory factor IL-1β stimulation. After cells were treated with DHA, cell apoptosis was measured. Western blot assay was used to detect protein expression of apoptosis-related factors (Bax, Bcl-2, and cleaved caspase-3) and mitogen-activated protein kinase (MAPK) signaling pathway family members, including extracellular signal-regulated kinase (ERK), c-JUN N-terminal kinase (JNK), and p38 MAPK. Our results show that IL-1β promotes the apoptosis of SW1353 cells, increases the expression of Bax and cleaved caspase-3, and activates the MAPK signaling pathway. In contrast, DHA inhibits the expression of IL-1β, inhibits IL-1β-induced cell apoptosis, and has a certain inhibitory effect on the activation of the MAPK signaling pathway. When the MAPK signaling pathway is inhibited by its inhibitors, the effects of DHA on SW1353 cells are weakened. Thus, DHA enhances the apoptosis of SW1353 cells through the MAPK signaling pathway., (© 2019 S. Karger AG, Basel.)

This study is designed to investigate the function of the miR-145 in the protection of neural stem cells (NSCs) through targeting mitogen-activated protein kinase (MAPK) pathway in the treatment of cerebral ischemic stroke rat. In our study, rat NSCs were selected and cultured in complete medium. The light microscopy was used to observe the morphology of NSCs at different times. The quantitative reverse transcriptase real-time polymerase chain reaction (qRT-PCR) was used to detect the miR-145 and other related mRNAs of the MARK pathway. The Western blotting was used to detect the activation of MAPK pathway and neuronal specific markers. The Immunofluorescence was used to detect the expression of the neuron-specific enolase. And the cell viability was detected by Cell Counting Kit (CCK)-8 assay. The flow cytometry was used to test the cell cycle and apoptosis. The ischemic stroke rat models were established and neural stem cell transplantation was performed. The neurological function score, balance beam experiment, and cortical Nissl staining were used to evaluate the postoperative neurological function in rats. The expression of miR-145, extracellular signal-regulated kinase (ERK), and p38 mRNA in rat NSCs increased in a time-dependent manner. Compared with the Blank group, the over-expression of miR-145 promoted the expression of related mRNA and protein of the MAPK pathway in NSCs, while the decreased expression of miR-145 suppressed the MAPK Pathways. Compared with the Blank group, over-expression of miR-145 in NSCs promoted the up-regulation of Cyclin D1, Nestin, neuron-specific enolase (NSE), and Glial fibrillary acidic protein (GFAP) proteins, enhanced the activity of NSCs, and promoted cell proliferation and differentiation, while inhibited the cell apoptosis and the Cleaved-caspase 3 expression. After treatment of NSCs in the SB203580 group, the Nestin, NSE, and GFAP were decreased; cell viability, proliferation and differentiation were inhibited, while Cleaved-caspase 3 protein and cell apoptosis rate increased. The results of animal experiments showed that compared with the Blank group, the walking ability and neurological impairment recovered rapidly in the rats after transplantation of NSCs with over-expression of miR-145, and more neurons were generated in the cortex. After the transplantation of SB203580-treated NSCs, the walking ability and neurological impairment of the rats were slower and the cortical neurons were less. We conclude that miR-145 protects the function of neuronal stem cells through targeting MAPK pathway in the treatment of cerebral ischemic stroke rat., (Copyright © 2018. Published by Elsevier Inc.)

The mitogen- and stress-activated protein kinases activated by the extracellular-signal-regulated kinase 1/2 and/or stress-activated protein kinase 2/p38 mitogen-activated protein kinase pathways are recruited to the regulatory region of a subset of genes termed immediate-early genes, often leading to their induction. These genes, many of which code for transcription factors, have been directly linked to the phenotypic events in carcinogenesis. In this paper, we focus on the mitogen- and stress-activated protein kinases; their discovery, activation, H3 phosphorylation and recent discoveries in their roles in cancer., (Copyright © 2018. Published by Elsevier Ltd.)

MAPK kinase 1 (MEK1) is an upstream protein kinase of extracellular signal regulated kinase (ERK), which activates the ERK/MAPK (mitogen activated protein kinase) pathway. Importantly, bioinformatic analysis has shown that there is a target complementary binding site between miR‑101 and MEK1. The present study aimed to ascertain whether or not miR‑101 plays a role in regulating MEK1 expression, ERK/MAPK pathway activity, and the proliferation and apoptosis in a diffuse large B cell lymphoma (DLBCL) cell line. DLBCL tumor samples were collected from patients in our hospital, and lymphatic tissues with reactive lymphoid hyperplasia were selected as controls. The patients were divided into high and low expression groups, and then the survival rate of the two groups was compared using Kaplan‑Meier method, as well the effect of miR‑101 and MEK1 mRNA expression on survival and prognosis was analyzed. The expression of miR‑101, MEK1 and p‑MEK1 between normal lymphoblastic cell lines (HCC1954 BL and NCI‑BL2009) and lymphoma cell lines (SU‑DHL‑4 and Farage) was compared. Lymphoma SU‑DHL‑4 and Farage cells were cultured in vitro, and then divided into the following groups: miR‑NC group; miR‑101 mimic group; siRNA‑NC group; and siRNA‑MEK1 group. The expression of miR‑101, MEK1, p‑MEK1, p‑ERK1/2 and Bcl‑2 was compared. Cell apoptosis was detected by flow cytometry, and cell proliferation was detected by EdU staining. The results showed that targeted regulation existed between miR‑101 and MEK1, and the decreased expression of miR‑101 was related to the pathogenesis and prognosis of DLBCL. Upregulation of miR‑101 inhibited DLBCL cell proliferation and facilitated apoptosis by inhibiting the expression of MEK1.