Phosphorylated FOXQ1, a novel substrate of JNK1, inhibits sorafenib-induced ferroptosis by activating ETHE1 in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a highly heterogeneous and malignant cancer with poor overall survival. The application of sorafenib is a major breakthrough in the treatment of HCC. In our study, FOXQ1 was significantly overexpressed in sorafenib-resistant HCC cells and suppressed sorafenib-induced ferroptosis. We found that phosphorylation of FOXQ1 at serine 248 is critical for the suppression of sorafenib-induced ferroptosis. Furthermore, as the upstream phosphorylation kinase of FOXQ1, JNK1, which is activated by sorafenib, can directly phosphorylate the serine 248 site of FOXQ1. Then, the phosphorylated FOXQ1 got a high affinity for the promoter of ETHE1 and activates its transcription. Further flow cytometry results showed that ETHE1 reduced intracellular lipid peroxidation and iron levels. Collectively, our study implicated the JNK1-FOXQ1-ETHE1 axis in HCC ferroptosis induced by sorafenib, providing mechanistic insight into sensitivity to sorafenib therapy of HCC.

Jnk1 and downstream signalling hubs regulate anxiety-like behaviours in a zebrafish larvae phenotypic screen.

Current treatments for anxiety and depression show limited efficacy in many patients, indicating the need for further research into the underlying mechanisms. JNK1 has been shown to regulate anxiety- and depressive-like behaviours in mice, however the effectors downstream of JNK1 are not known. Here we compare the phosphoproteomes from wild-type and Jnk1-/- mouse brains and identify JNK1-regulated signalling hubs. We next employ a zebrafish (Danio rerio) larvae behavioural assay to identify an antidepressant- and anxiolytic-like (AA) phenotype based on 2759 measured stereotypic responses to clinically proven antidepressant and anxiolytic (AA) drugs. Employing machine learning, we classify an AA phenotype from extracted features measured during and after a startle battery in fish exposed to AA drugs. Using this classifier, we demonstrate that structurally independent JNK inhibitors replicate the AA phenotype with high accuracy, consistent with findings in mice. Furthermore, pharmacological targeting of JNK1-regulated signalling hubs identifies AKT, GSK-3, 14-3-3 ζ/ε and PKCε as downstream hubs that phenocopy clinically proven AA drugs. This study identifies AKT and related signalling molecules as mediators of JNK1-regulated antidepressant- and anxiolytic-like behaviours. Moreover, the assay shows promise for early phase screening of compounds with anti-stress-axis properties and for mode of action analysis.

Di-n-butyl phthalate induces toxicity in male fetal mouse testicular development by regulating the MAPK signaling pathway.

"White pollution" has a significant impact on male reproduction. Di-n-butyl phthalate (DBP) is one of the most important factors in this type of pollution. Currently, research from international sources has demonstrated the significant reproductive toxicity of DBP. However, most of these studies have focused mainly on hormones expression at the protein and mRNA levels and the specific molecular targets of DBP and its mechanisms of action remain unclear. In this study, we established a Sprague Dawley pregnant mouse model exposed to DBP, and all male offspring were immediately euthanized at birth and bilateral testes were collected. We found through transcriptome sequencing that cell apoptosis and MAPK signaling pathway are the main potential pathways for DBP induced reproductive toxicity. Molecular biology analyses revealed a significant increase in the protein levels of JNK1(MAPK8) and BAX, as well as a significant increase in the BAX/BCL2 ratio after DBP exposure. Therefore, we propose that DBP induces reproductive toxicity by regulating JNK1 expression to activate the MAPK signaling pathway and induce reproductive cell apoptosis. In conclusion, our study provides the first evidence that the MAPK signaling pathway is involved in DBP-induced reproductive toxicity and highlights the importance of JNK1 as a potential target of DBP in inducing reproductive toxicity.

In silico studies on the anti-acne potential of Garcinia mangostana xanthones and benzophenones.

Garcinia mangostana fruits are used traditionally for inflammatory skin conditions, including acne. In this study, an in silico approach was employed to predict the interactions of G. mangostana xanthones and benzophenones with three proteins involved in the pathogenicity of acne, namely the human JNK1, Cutibacterium acnes KAS III and exo-ß-1,4-mannosidase. Molecular docking analysis was performed using Autodock Vina. The highest docking scores and size-independent ligand efficiency values towards JNK1, C. acnes KAS III and exo-ß-1,4-mannosidase were obtained for garcinoxanthone T, gentisein/2,4,6,3',5'-pentahydroxybenzophenone and mangostanaxanthone VI, respectively. To the best of our knowledge, this is the first report of the potential of xanthones and benzophenones to interact with C. acnes KAS III. Molecular dynamics simulations using GROMACS indicated that the JNK1-garcinoxanthone T complex had the highest stability of all ligand-protein complexes, with a high number of hydrogen bonds predicted to form between this ligand and its target. Petra/Osiris/Molinspiration (POM) analysis was also conducted to determine pharmacophore sites and predict the molecular properties of ligands influencing ADMET. All ligands, except for mangostanaxanthone VI, showed good membrane permeability. Garcinoxanthone T, gentisein and 2,4,6,3',5'-pentahydroxybenzophenone were identified as the most promising compounds to explore further, including in experimental studies, for their anti-acne potential.

Chronic intermittent hypoxia-induced oxidative stress activates TRB3 and phosphorylated JNK to mediate insulin resistance and cell apoptosis in the pancreas.

This study explores the potential mechanisms of obstructive sleep apnoea (OSA) complicates type 2 diabetes mellitus (T2DM) by which chronic intermittent hypoxia (CIH) induces insulin resistance and cell apoptosis in the pancreas through oxidative stress. Four- and eight-week CIH rat models were established, and Tempol (100 mg/kg/d), was used as an oxidative stress inhibitor. This study included five groups: 4-week CIH, 4-week CIH-Tempol, 8-week CIH, 8-week CIH-Tempol and normal control (NC) groups. Fasting blood glucose and insulin levels were measured in the serum. The expression levels of 8-hidroxy-2-deoxyguanosine (8-OHdG), tribbles homologue 3 (TRB3), c-Jun N-terminal kinase (JNK), phosphorylated JNK (p-JNK), insulin receptor substrate-1 (IRS-1), phosphorylated IRS-1 (Ser307) (p-IRS-1ser307 ), protein kinase B (AKT), phosphorylated AKT (Ser473) (p-AKTser473 ), B cell lymphoma protein-2 (Bcl-2), cleaved-caspase-3 (Cl-caspase-3), and the islet cell apoptosis were detected in the pancreas. CIH induced oxidative stress in the pancreas. Compared with that in the NC group and CIH-Tempol groups individually, the homeostasis model assessment of insulin resistance (HOMA-IR) and apoptosis of islet cells was increased in the CIH groups. CIH-induced oxidative stress increased the expression of p-IRS-1Ser307 and decreased the expression of p-AKTSer473 . The expression levels of TRB3 and p-JNK were higher in the CIH groups than in both the CIH-Tempol and NC groups. Meanwhile, the expressions of Cl-caspase-3 and Bcl-2 were upregulated and downregulated, respectively, in the CIH groups. Hence, the present study demonstrated that CIH-induced oxidative stress might not only induce insulin resistance but also islet cell apoptosis in the pancreas through TRB3 and p-JNK.

MicroRNA miR-181d-5p regulates the MAPK signaling pathway by targeting mitogen-activated protein kinase 8 (MAPK8) to improve lupus nephritis.

BACKGROUND: Lupus nephritis (LN) is a common immune disease. The microRNA (miR)-181d-5p is a potential target for treating kidney injury. However, the therapeutic role of miR-181d-5p in LN has not been investigated. This study aimed to investigate the role of miR-181d-5p in targeting mitogen-activated protein kinase 8 (MAPK8) and stimulating the MAPK signaling pathway in LN. METHODS: RT-qPCR was performed to identify the variations in miR-181d-5p expression in peripheral blood mononuclear cells (PBMCs) obtained from 42 LN patients, 30 healthy individuals, 6 MRL/lpr mice and 6 C57BL/6 mice. Western blot was used to detect the effect of miR-181d-5p on the MAPK signaling pathway in THP-1 cells and MRL/lpr mice. Enzyme-linked immunosorbent assay (ELISA) was utilized to detect the effect of miR-181d-5p on antinuclear antibodies and inflammatory factors. A dual-luciferase reporter assay was used to verify whether miR-181d-5p directly targets MAPK8. Flow cytometry was performed to evaluate apoptosis rates in transfected THP-1 cells. RESULTS: miR-181d-5p expression was downregulated in PBMCs of LN patients (P < 0.01) and MRL/lpr mice (P < 0.05). A dual luciferase reporter assay demonstrated that miR-181d-5p inhibits MAPK8 (P < 0.01). Overexpression of miR-181d-5p inhibited the phosphorylation of p38 (P < 0.001) and p44/42 (P < 0.01). Moreover, miR-181d-5p decreased the apoptosis rate of THP-1 cells (P < 0.001), and reduced the secretion of IL-6 (P < 0.01) and TNF-α (P < 0.01). Furthermore, overexpression of miR-181d-5p decreased anti-dsDNA antibody (P < 0.05), anti-Sm antibody (P < 0.01), and fibrosis levels in MRL/lpr mice. CONCLUSION: Upregulation of miR-181d-5p showed anti-inflammatory and anti-apoptotic effects on THP-1 cells in vitro and kidney injury in vivo. These effects were achieved by miR-181d-5p targeting MAPK8 to inhibit phosphorylation of p38 and p44/42. These results may offer new insights for improving therapeutic strategies against lupus nephritis.

JNK promotes the progression of castration-resistant prostate cancer.

BACKGROUND: Prostate cancer is one of the most common cancers in men worldwide. This study aims to elucidate the roles of c-Jun N-terminal kinase (JNK) in the progression of castration-resistant prostate cancer (CRPC). METHODS: JNK overexpressing and knockdown cell lines were established on the PC-3 prostate cell line. qPCR and Western blotting were performed to determine the mRNA and protein levels of target genes in prostate tissues and cell lines. MTT and Matrigel invasion assays were conducted to evaluate the cell viability and invasive ability, respectively. The Kaplan-Meier estimator was performed to estimate the overall survival rate and second progression-free survival rate. Pearson's correlation coefficient was used to evaluate the relationship between JNK and prostate-specific antigen (PSA). RESULTS: Relative JNK expression was correlated with Gleason score and PSA value in patients with CRPC. Kaplan-Meier analysis revealed that patients with low JNK expression exhibited high overall survival and second progression-free survival rate. In vitro assays demonstrated that JNK overexpression promoted cell viability and invasion as well as the protein expressions of extracellular signal-regulated kinase (ERK) and matrix metalloproteinase 1 (MMP1) in PC-3 cell lines. CONCLUSIONS: JNK overexpression promotes the development of CRPC via the regulation of ERK and MMP1.

Physical exercise elicits UPRmt in the skeletal muscle: The role of c-Jun N-terminal kinase.

OBJECTIVE: The mitochondrial unfolded protein response (UPRmt) is an adaptive cellular response to stress to ensure mitochondrial proteostasis and function. Here we explore the capacity of physical exercise to induce UPRmt in the skeletal muscle. METHODS: Therefore, we combined mouse models of exercise (swimming and treadmill running), pharmacological intervention, and bioinformatics analyses. RESULTS: Firstly, RNA sequencing and Western blotting analysis revealed that an acute aerobic session stimulated several mitostress-related genes and protein content in muscle, including the UPRmt markers. Conversely, using a large panel of isogenic strains of BXD mice, we identified that BXD73a and 73b strains displayed low levels of several UPRmt-related genes in the skeletal muscle, and this genotypic feature was accompanied by body weight gain, lower locomotor activity, and aerobic capacity. Finally, we identified that c-Jun N-terminal kinase (JNK) activation was critical in exercise-induced UPRmt in the skeletal muscle since pharmacological JNK pathway inhibition blunted exercise-induced UPRmt markers in mice muscle. CONCLUSION: Our findings provide new insights into how exercise triggers mitostress signals toward the oxidative capacity in the skeletal muscle.

Cold Stress Induces Apoptosis in Silver Pomfret via DUSP-JNK Pathway.

We cultured silver pomfret for 20 days, decreasing water temperature from 18 to 8 ℃, and sampled muscle every 5 days. Muscle fiber degeneration and apoptosis began to increase at 13 ℃ detected by HE and TUNEL staining. Further analysis of transcriptome revealed that several apoptosis-related pathways were highly enriched by differentially expressed genes (DEGs). We analyzed 10 DEGs from these pathways by RT-qPCR during the temperature-decreasing process. JNK1, PIDD, CytC, Casp 3, and GADD45 were up-regulated after 15 and 20 days, while DUSP3, JNK2, and PARP genes were down-regulated after 15 and 20 days. DUSP5 was up-regulated from 10 to 20 days, and C-JUN was up-regulated after 20 days. We analyzed apoptosis in PaM cells under different temperatures (26 ℃, 23 ℃, 20 ℃, 17 ℃, and 14 ℃). The cell viability significantly declined from 14 to 20 ℃; the TUNEL and IHC results showed that the apoptosis signal increased with the temperature dropping, especially in 17 ℃ and 14 ℃; DUSP5, JNK1, CytC, C-JUN, Casp 3, and GADD45 were up-regulated at 17 ℃ and 14 ℃, and PIDD was up-regulated at 20 ℃, 17 ℃, and 14 ℃. DUSP3 was up-regulated at 20 ℃ but down-regulated at 17 ℃ and 14 ℃, and PARP was down-regulated at 17 ℃ and 14 ℃. JNK2 was up-regulated at 20 ℃ but down-regulated at 17 ℃ and 14 ℃. Our results suggest that DUSP could help inhibit apoptosis in the initial stage of cold stress, but low temperature could down-regulate it and up-regulate JNK-C-JUN, inducing apoptosis in a later stage. These data provide a basis for the study of the response mechanism of fish to cold.

Aging Differentially Affects Axonal Autophagosome Formation and Maturation.

Misregulation of neuronal macroautophagy/autophagy has been implicated in age-related neurodegenerative diseases. We compared autophagosome formation and maturation in primary murine neurons during development and through aging to elucidate how aging affects neuronal autophagy. We observed an age-related decrease in the rate of autophagosome formation leading to a significant decrease in the density of autophagosomes along the axon. Next, we identified a surprising increase in the maturation of autophagic vesicles in neurons from aged mice. While we did not detect notable changes in endolysosomal content in the distal axon during early aging, we did observe a significant loss of acidified vesicles in the distal axon during late aging. Interestingly, we found that autophagic vesicles were transported more efficiently in neurons from adult mice than in neurons from young mice. This efficient transport of autophagic vesicles in both the distal and proximal axon is maintained in neurons during early aging, but is lost during late aging. Our data indicate that early aging does not negatively impact autophagic vesicle transport nor the later stages of autophagy. However, alterations in autophagic vesicle transport efficiency during late aging reveal that aging differentially impacts distinct aspects of neuronal autophagy.Abbreviations: ACAP3: ArfGAP with coiled-coil, ankyrin repeat and PH domains 3; ARF6: ADP-ribosylation factor 6; ATG: autophagy related; AVs: autophagic vesicles; DCTN1/p150Glued: dynactin 1; DRG: dorsal root ganglia; GAP: GTPase activating protein; GEF: guanine nucleotide exchange factor; LAMP2: lysosomal-associated protein 2; LysoT: LysoTracker; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MAPK8IP1/JIP1: mitogen-activated protein kinase 8 interacting protein 1; MAPK8IP3/JIP3: mitogen-activated protein kinase 8 interacting protein 3; mCh: mCherry; PE: phosphatidylethanolamine.

MAPK8 and CAPN1 as potential biomarkers of intervertebral disc degeneration overlapping immune infiltration, autophagy, and ceRNA.

Background: Intervertebral disc degeneration (IDD) is one of the most common health problems in the elderly and a major causative factor in low back pain (LBP). An increasing number of studies have shown that IDD is closely associated with autophagy and immune dysregulation. Therefore, the aim of this study was to identify autophagy-related biomarkers and gene regulatory networks in IDD and potential therapeutic targets. Methods: We obtained the gene expression profiles of IDD by downloading the datasets GSE176205 and GSE167931 from the Gene Expression Omnibus (GEO) public database. Subsequently, differentially expressed genes (DEGs) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, gene ontology (GO), and gene set enrichment analysis (GSEA) were performed to explore the biological functions of DEGs. Differentially expressed autophagy-related genes (DE-ARGs) were then crossed with the autophagy gene database. The hub genes were screened using the DE-ARGs protein-protein interaction (PPI) network. The correlation between the hub genes and immune infiltration and the construction of the gene regulatory network of the hub genes were confirmed. Finally, quantitative PCR (qPCR) was used to validate the correlation of hub genes in a rat IDD model. Results: We obtained 636 DEGs enriched in the autophagy pathway. Our analysis revealed 30 DE-ARGs, of which six hub genes (MAPK8, CTSB, PRKCD, SNCA, CAPN1, and EGFR) were identified using the MCODE plugin. Immune cell infiltration analysis revealed that there was an increased proportion of CD8+ T cells and M0 macrophages in IDD, whereas CD4+ memory T cells, neutrophils, resting dendritic cells, follicular helper T cells, and monocytes were much less abundant. Subsequently, the competitive endogenous RNA (ceRNA) network was constructed using 15 long non-coding RNAs (lncRNAs) and 21 microRNAs (miRNAs). In quantitative PCR (qPCR) validation, two hub genes, MAPK8 and CAPN1, were shown to be consistent with the bioinformatic analysis results. Conclusion: Our study identified MAPK8 and CAPN1 as key biomarkers of IDD. These key hub genes may be potential therapeutic targets for IDD.

Repeated Rounds of Gonadotropin Stimulation Induce Imbalance in the Antioxidant Machinery and Activation of Pro-Survival Proteins in Mouse Oviducts.

Controlled ovarian stimulation (COS) through gonadotropin administration has become a common procedure in assisted reproductive technologies. COS's drawback is the formation of an unbalanced hormonal and molecular environment that could alter several cellular mechanisms. On this basis, we detected the presence of mitochondrial DNA (mtDNA) fragmentation, antioxidant enzymes (catalase; superoxide dismutases 1 and 2, SOD-1 and -2; glutathione peroxidase 1, GPx1) and apoptotic (Bcl-2-associated X protein, Bax; cleaved caspases 3 and 7; phosphorylated (p)-heat shock protein 27, p-HSP27) and cell-cycle-related proteins (p-p38 mitogen-activated protein kinase, p-p38 MAPK; p-MAPK activated protein kinase 2, p-MAPKAPK2; p-stress-activated protein kinase/Jun amino-terminal kinase, p-SAPK/JNK; p-c-Jun) in the oviducts of unstimulated (Ctr) and repeatedly hyperstimulated (eight rounds, 8R) mice. While all the antioxidant enzymes were overexpressed after 8R of stimulation, mtDNA fragmentation decreased in the 8R group, denoting a present yet controlled imbalance in the antioxidant machinery. Apoptotic proteins were not overexpressed, except for a sharp increase in the inflammatory-related cleaved caspase 7, accompanied by a significant decrease in p-HSP27 content. On the other hand, the number of proteins involved in pro-survival mechanisms, such as p-p38 MAPK, p-SAPK/JNK and p-c-Jun, increased almost 50% in the 8R group. Altogether, the present results demonstrate that repeated stimulations cause the activation of the antioxidant machinery in mouse oviducts; however, this is not sufficient to induce apoptosis, and is efficiently counterbalanced by activation of pro-survival proteins.

Novel Tryptanthrin Derivatives with Selectivity as c-Jun N-Terminal Kinase (JNK) 3 Inhibitors.

The c-Jun N-terminal kinase (JNK) family includes three proteins (JNK1-3) that regulate many physiological processes, including cell proliferation and differentiation, cell survival, and inflammation. Because of emerging data suggesting that JNK3 may play an important role in neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease, as well as cancer pathogenesis, we sought to identify JNK inhibitors with increased selectivity for JNK3. A panel of 26 novel tryptanthrin-6-oxime analogs was synthesized and evaluated for JNK1-3 binding (Kd) and inhibition of cellular inflammatory responses. Compounds 4d (8-methoxyindolo[2,1-b]quinazolin-6,12-dione oxime) and 4e (8-phenylindolo[2,1-b]quinazolin-6,12-dione oxime) had high selectivity for JNK3 versus JNK1 and JNK2 and inhibited lipopolysaccharide (LPS)-induced nuclear factor-κB/activating protein 1 (NF-κB/AP-1) transcriptional activity in THP-1Blue cells and interleukin-6 (IL-6) production by MonoMac-6 monocytic cells in the low micromolar range. Likewise, compounds 4d, 4e, and pan-JNK inhibitor 4h (9-methylindolo[2,1-b]quinazolin-6,12-dione oxime) decreased LPS-induced c-Jun phosphorylation in MonoMac-6 cells, directly confirming JNK inhibition. Molecular modeling suggested modes of binding interaction of these compounds in the JNK3 catalytic site that were in agreement with the experimental data on JNK3 binding. Our results demonstrate the potential for developing anti-inflammatory drugs based on these nitrogen-containing heterocyclic systems with selectivity for JNK3.

Spatio-temporal pattern of c-Jun N-terminal kinase isoforms in the cochleae of C57BL/6J mice with presbycusis.

The c-Jun N-terminal kinase (JNK) pathway is a vital component of the mitogen-activated protein kinase cascade, which regulates cell death and survival. The present study aimed to explore the Spatio-temporal changes in all JNK isoforms in the cochleae of C57/BL6J mice with age-related hearing loss. Changes in the three isoforms of JNKs in the cochleae of an animal model with presbycusis and the senescent HEI-OC1 cell line were tested by immunohistochemistry staining and western blotting. Our results demonstrated that all three JNK isoforms are distributed in the cochleae, and the expression patterns of JNK1, JNK2, and JNK3 differed in hair cells, spiral ganglion neurons, and stria vascularis, with great significance in the cochleae of adult C57BL/6J mice. The levels of JNK1, JNK2, and JNK3 showed various spatio-temporal changes in the aging mice. In a senescent hair cell model, changes in JNK1, JNK2, and JNK3 expression levels were similar to those observed in the cochleae. Our study is the first to show that JNK3 is highly expressed in the hair cells of C57BL/6J mice and further increases in conjunction with age-related hearing loss, suggesting that it may play a more critical role than previously believed in hair cell loss and spiral ganglion degeneration.

Synthesis-accessibility-oriented design of c-Jun N-terminal kinase 1 inhibitor.

Idiopathic pulmonary fibrosis (IPF) is a severe and progressive lung disease with poor prognosis and limited treatment options. The c-Jun N-Terminal Kinase 1 (JNK1), a key component of the MAPK pathway, has been implicated in the pathogenesis of IPF and represents a potential therapeutic target. However, the development of JNK1 inhibitors has been slowed, partly due to synthetic complexity in medicinal chemistry modification. Here, we report a synthesis-accessibility-oriented strategy for designing JNK1 inhibitors based on computational prediction of synthetic feasibility and fragment-based molecule generation. This strategy led to the discovery of several potent JNK1 inhibitors, such as compound C6 (IC50 = 33.5 nM), which exhibited comparable activity to the clinical candidate CC-90001 (IC50 = 24.4 nM). The anti-fibrotic effect of C6 was further confirmed in animal model of pulmonary fibrosis. Moreover, compound C6 could be synthesized in only two steps, compared to nine steps for CC-90001. Our findings suggest that compound C6 is a promising lead for further optimization and development as a novel anti-fibrotic agent targeting JNK1. In addition, the discovery of C6 also demonstrates the feasibility of synthesis-accessibility-oriented strategy in lead discovery.

Glyceraldehyde-3-phosphate dehydrogenase regulates activation of c-Jun N-terminal kinase under oxidative stress.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) acts as a sensor under oxidative stress, leading to induction of various biological responses. Given that mitogen-activated protein kinase (MAPK) signaling pathways mediate cellular responses to a wide variety of stimuli, including oxidative stress, here, we aimed to elucidate whether a cross-talk cascade between GAPDH and MAPKs occurs under oxidative stress. Of the three typical MAPKs investigated-extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase (JNK)-we found that hydrogen peroxide (H2O2)-induced JNK activation is significantly reduced in HEK293 cells treated with small-interfering (si)RNA targeting GAPDH. Co-immunoprecipitation with a GAPDH antibody further revealed protein-protein interactions between GAPDH and JNK in H2O2-stmulated cells. Notably, both JNK activation and these interactions depend on oxidation of the active-site cysteine (Cys152) in GAPDH, as demonstrated by rescue experiments with either exogenous wild-type GAPDH or the cysteine-substituted mutant (C152A) in endogenous GAPDH-knockdown HEK293 cells. Moreover, H2O2-induced translocation of Bcl-2-associated X protein (Bax) into mitochondria, which occurs downstream of JNK activation, is attenuated by endogenous GAPDH knockdown in HEK293 cells. These results suggest a novel role for GAPDH in the JNK signaling pathway under oxidative stress.

Osmotic pressure induces translocation of aquaporin-8 by P38 and JNK MAPK signaling pathways in patients with functional constipation.

BACKGROUND: Aquaporins (AQPs) maintain fluid homeostasis in the colon. The role of colonic AQPs in the pathophysiology of functional constipation (FC) remains largely unknown. AIM: To explore variations in aquaporins and investigate their underlying mechanisms. METHODS: Colonic biopsies were collected from patients with FC and healthy controls. The expression and localization of AQPs were evaluated using quantitative real-time polymerase chain reaction (qRT-PCR), western blot analysis, and immunofluorescence assays. Furthermore, osmotic pressure-induced cell model was used in vitro to investigate the potential relationship between AQP8 and osmotic pressure, and to reveal the underlying mechanisms. RESULTS: Upregulation of AQP3 and AQP8, and downregulation of AQP1, AQP7, AQP9, AQP10, and AQP11 were observed in the patients with functional constipation. Furthermore, cellular translocation of AQP8 from the cytoplasm to the plasma membrane was observed in patients with FC. Mechanistically, the increase in osmotic pressure could activate the Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) signaling pathways, and subsequently promote the upregulation and translocation of AQP8. CONCLUSION: Upregulation of AQP8 and AQP3, and translocation of AQP8 were observed in colon biopsies from patients with FC. The p38 and JNK MAPK signaling pathways are involved in the regulation of osmotic pressure-induced AQP8 variation.

Novel 2,4- diaminopyrimidine 5-carboxamides as c-Jun N-terminal Kinase Inhibitors for Treating the Liver Fibrotic Disorder.

Diaminopyrimidine compounds having the following general structure (I), compositions comprising an effective amount of a diaminopyrimidine compound, and methods for treating or preventing fibrotic liver disorders or other diseases associated with the JNK pathway are discussed in this patent study.

Development of a Covalent Inhibitor of c-Jun N-Terminal Protein Kinase (JNK) 2/3 with Selectivity over JNK1.

The c-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein kinase (MAPK) family, which includes JNK1-JNK3. Interestingly, JNK1 and JNK2 show opposing functions, with JNK2 activity favoring cell survival and JNK1 stimulating apoptosis. Isoform-selective small molecule inhibitors of JNK1 or JNK2 would be useful as pharmacological probes but have been difficult to develop due to the similarity of their ATP binding pockets. Here, we describe the discovery of a covalent inhibitor YL5084, the first such inhibitor that displays selectivity for JNK2 over JNK1. We demonstrated that YL5084 forms a covalent bond with Cys116 of JNK2, exhibits a 20-fold higher Kinact/KI compared to that of JNK1, and engages JNK2 in cells. However, YL5084 exhibited JNK2-independent antiproliferative effects in multiple myeloma cells, suggesting the existence of additional targets relevant in this context. Thus, although not fully optimized, YL5084 represents a useful chemical starting point for the future development of JNK2-selective chemical probes.

Stress-Activated Protein Kinase JNK Modulates Depression-like Behaviors in Mice.

Stress is considered as a major cause of depression. C-Jun N-terminal kinase (JNK) is a member of the stress-induced mitogen activated protein (MAP) kinase family which is often activated through phosphorylation. Clinical studies and animal experiments have found that abnormal phosphorylation/activation of JNK exists in the occurrence of various psychiatric diseases. Recently, several studies linked JNK kinase activity to depression. However, whether excessive activation of JNK activity is directly responsible for the occurrence of depression and the underlying mechanisms remain unclear. Here, we constructed a conditional transgenic mouse which is specifically expressing MKK7-JNK1 (CAJNK1) in the central nervous system. CAJNK1 mice showed activation of JNK and lead to depression-like behavior in mice. Transcriptome analysis indicates reduced expression of synaptic-associated genes in CAJNK1 mice brains. Consistently, we found abnormal dendritic spine development and PSD95 downregulation in CAJNK1 hippocampal neurons. Our studies provide compelling evidence that activation of JNK as an intrinsic factor leading to depression-like behavior in mice provides direct clues for targeting the JNK activity as a potential therapeutic strategy for depression.