Cardiac tumour necrosis factor receptor-associated factor 7 mediates the ubiquitination of apoptosis signal-regulating kinase 1 and aggravates cardiac hypertrophy.

AIMS: Cardiac remodelling is a common pathophysiological process in the development of various cardiovascular diseases, but there is still a lack of effective interventions. Tumour necrosis receptor-associated factor 7 (TRAF7) belongs to the tumour necrosis factor receptor-associated factor family and plays an important role in biological processes. Previous studies have shown that TRAF7 mutations lead to congenital defects and malformations of the heart. However, the molecular mechanisms of TRAF7 in the underlying pathogenesis of pathological cardiac hypertrophy remain unknown. We aim to study the molecular mechanisms and effects of TRAF7 in cardiac remodelling and whether it has the potential to become a therapeutic target for cardiac remodelling. METHODS AND RESULTS: The pressure overload-induced cardiac hypertrophy model in mice was established via transverse aortic constriction (TAC) surgery, and cardiomyocytes were treated with phenylephrine (PE) to induce hypertrophic phenotype. Levels of cardiac dysfunction and remodelling were measured with echocardiography and tissue or cell staining. RNA sequencing, western blot, qRT-PCR, co-immunoprecipitation, and in vivo ubiquitination assays were used to explore the molecular mechanisms. The results showed that the expression of TRAF7 increased gradually during the development of hypertrophy. Accordingly, TRAF7 significantly exacerbated the PE-induced enlargement of primary neonatal Sprague-Dawley rat cardiomyocytes, whereas TRAF7 knockdown alleviated the hypertrophic phenotype in primary cardiomyocytes. Cardiac-specific overexpression of TRAF7 accelerated hypertrophic phenotype in mice and cardiac-specific Traf7 conditional knockout mice improved hypertrophic phenotype induced by TAC. Mechanistically, TRAF7 directly interacted with apoptosis signal-regulating kinase-1 (ASK1) and promoted ASK1 phosphorylation by mediating the K63-linked ubiquitination of ASK1 in response to PE stimulation, which then promoted ASK1 activation and downstream signalling during cardiac hypertrophy. Notably, the pro-hypertrophic effect of TRAF7 was largely blocked by GS4997 in vitro and cardiac-specific Ask1 conditional knockout in vivo. CONCLUSION: In summary, we identified TRAF7 as an essential regulator during cardiac hypertrophy, and modulation of the regulatory axis between TRAF7 and ASK1 could be a novel therapeutic strategy to prevent this pathological process.

Multi-omic human pancreatic islet endoplasmic reticulum and cytokine stress response mapping provides type 2 diabetes genetic insights.

Endoplasmic reticulum (ER) and inflammatory stress responses contribute to islet dysfunction in type 2 diabetes (T2D). Comprehensive genomic understanding of these human islet stress responses and whether T2D-associated genetic variants modulate them is lacking. Here, comparative transcriptome and epigenome analyses of human islets exposed ex vivo to these stressors revealed 30% of expressed genes and 14% of islet cis-regulatory elements (CREs) as stress responsive, modulated largely in an ER- or cytokine-specific fashion. T2D variants overlapped 86 stress-responsive CREs, including 21 induced by ER stress. We linked the rs6917676-T T2D risk allele to increased islet ER-stress-responsive CRE accessibility and allele-specific ß cell nuclear factor binding. MAP3K5, the ER-stress-responsive putative rs6917676 T2D effector gene, promoted stress-induced ß cell apoptosis. Supporting its pro-diabetogenic role, MAP3K5 expression correlated inversely with human islet ß cell abundance and was elevated in T2D ß cells. This study provides genome-wide insights into human islet stress responses and context-specific T2D variant effects.

Kaempferol attenuates cyclosporine-induced renal tubular injury via inhibiting the ROS-ASK1-MAPK pathway.

Cyclosporine (CSA) is a widely used immunosuppressive medication. CSA nephrotoxicity severely limits its application. Kaempferol (KPF), a naturally occurring phenolic compound, has a promising protective effect in reducing CSA-induced renal tubular injury, but the mechanism remains unknown. Our study aimed to determine the protective role of KPF against CSA-induced renal tubular injury. C57/B6 mice and the NRK-52E cell line were employed. CSA worsened renal function in mice, causing detachment and necrosis of tubular cells, leading to tubular vacuolation and renal interstitial fibrosis. CSA caused the detachment, rupture, and death of tubular cells in vitro, resulting in cell viability loss. KPF mitigated all these injurious alterations. KPF hindered CSA-induced ROS generation and protected renal tubular epithelial cells, similar to the antioxidant NAC. CSA lowered SOD activity and GSH levels while increasing MDA levels, and KPF ameliorated these changes. CSA caused phosphorylation of ASK1, JNK, and p38, similar to H2O2, whereas KPF significantly inhibited these changes. In conclusion, KPF reduces CSA-induced tubular epithelial cell injury via its antioxidant properties, inhibits the phosphorylation of ASK1, and inhibits the phosphorylation of p38 and JNK, implying that the synergistic use of KPF in CSA immunotherapy may be a promising option to reduce CSA-evoked renal injury.

Quercetin antagonizes apoptosis, autophagy and immune dysfunction induced by di(2-ethylhexyl) phthalate via ROS/ASK1/JNK pathway.

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer that can damage various organizations and physiques through oxidative stress. Quercetin (Que) is a rich polyphenol flavonoid with good anti-inflammatory and antioxidant effects. However, the protection mechanism of Que against DEHP exposure-induced IPEC-J2 cell injury and the implication of autophagy, apoptosis and immunity are still unclear. In this experiment, we looked into the toxicity regime of DEHP exposure on IPEC-J2 cells and the antagonistic function of Que on DEHP. In the experiment, 135 µM DEHP and/or 80 µM Que were used to treat the IPEC-J2 cells for 24h. Experiments indicated that DEHP exposure can cause increased reactive oxygen species (ROS) levels leading to oxidative stress, decreased CAT, T-AOC and GSH-Px activities, increased MDA and H2O2 accumulation, activated the ASK1/JNK signalling pathway, and further increases in the levels of apoptosis markers Bax, Caspase3, Caspase9, and Cyt-c, while reduced the Bcl-2 expression. DEHP also increased the expression of genes linked to autophagy (ATG5, Beclin1, LC3), while decreasing the expression of P62. Additionally, DEHP exposure led to elevated levels of IL1-ß, IL-6, MCP-1, and TNF expression. When exposed to Que alone, there were no significant changes in cellular oxidative stress level, ASK1/JNK signalling pathway expression level, apoptosis, autophagy and cellular immune function. The combination of DEHP and Que treatment remarkably decreased the proportion of autophagy and apoptosis, and recovered cellular immunity. In summary, Que can attenuate DEHP-induced apoptosis and autophagy in IPEC-J2 cells by regulating the ROS/ASK1/JNK signalling pathway and improving the immune dysfunction of IPEC-J2 cells.

RING finger protein 5 protects against acute myocardial infarction by inhibiting ASK1.

BACKGROUND: Myocardial infarction (MI) is a major disease with high morbidity and mortality worldwide. However, existing treatments are far from satisfactory, making the exploration of potent molecular targets more imperative. The E3 ubiquitin ligase RING finger protein 5 (RNF5) has been previously reported to be involved in several diseases by regulating ubiquitination-mediated protein degradation. Nevertheless, few reports have focused on its function in cardiovascular diseases, including MI. METHODS: In this study, we established RNF5 knockout mice through precise CRISPR-mediated genome editing and utilized left anterior descending coronary artery ligation in 9-11-week-old male C57BL/6 mice. Subsequently, serum biochemical analysis and histopathological examination of heart tissues were performed. Furthermore, we engineered adenoviruses for modulating RNF5 expression and subjected neonatal rat cardiomyocytes to oxygen-glucose deprivation (OGD) to mimic ischemic conditions, demonstrating the impact of RNF5 manipulation on cellular viability. Gene and protein expression analysis provided insights into the molecular mechanisms. Statistical methods were rigorously employed to assess the significance of experimental findings. RESULTS: We found RNF5 was downregulated in infarcted heart tissue of mice and NRCMs subjected to OGD treatment. RNF5 knockout in mice resulted in exacerbated heart dysfunction, more severe inflammatory responses, and increased apoptosis after MI surgery. In vitro, RNF5 knockdown exacerbated the OGD-induced decline in cell activity, increased apoptosis, while RNF5 overexpression had the opposite effect. Mechanistically, it was proven that the kinase cascade initiated by apoptosis signal-regulating kinase 1 (ASK1) activation was closely regulated by RNF5 and mediated RNF5's protective function during MI. CONCLUSIONS: We demonstrated the protective effect of RNF5 on myocardial infarction and its function was dependent on inhibiting the activation of ASK1, which adds a new regulatory component to the myocardial infarction associated network and promises to enable new therapeutic strategy.

Down-regulation of PGAM5 attenuates spinal cord injury-induced neuronal injury by inhibiting ASK-1/p38/NF-kB signaling.

INTRODUCTION: The morbidity and mortality of spinal cord injury (SCI) are increasing year by year. It is of vital importance to ascertain the mechanism of SCI. Phosphoglycerate mutase family member 5 (PGAM5) is viewed as a molecular marker of SCI, but its specific role in SCI is elusive. MATERIAL AND METHODS: Following establishment of the SCI mouse model, the pathological examination of the spinal cord was initially assessed using H&E staining. PGAM5 expression in spinal cord tissues was appraised utilizing immunohistochemistry and RT-qPCR. Subsequently, after the expression of PGAM5 in SCI mice was inhibited by adenovirus transfection, the degree of SCI was determined, and the motor ability of hind limbs was estimated with the BBB score. In addition, the apoptosis of neurons, microglia activation and the generation of inflammatory cytokines in the spinal cord of mice were detected. Next, at the cellular level, PGAM5 expression was inhibited in the BV2 microglial cells induced by lipopolysaccharide (LPS), so as to explore the effects of down-regulation of PGAM5 on the activation, inflammation and apoptosis of neurons. Finally, western blot was applied for the appraisement of apoptosis signal-regulating kinase-1 (ASK-1)/p38/nuclear factor-kappa B (NF-kB) signaling-associated proteins. RESULTS: PGAM5 expression in SCI mice was found to be raised. Inhibition of PGAM5 expression in SCI mice can significantly reduce spinal cord pathological injury, SCI-induced neuronal apoptosis, microglial cell activation and inflammation. The above regulatory process might be realized through the ASK-1/p38/NF-kB signaling pathway mediated by PGAM5. CONCLUSIONS: Down-regulation of PGAM5 attenuated SCI-induced neuronal injury by inhibiting ASK-1/p38/NF-kB signaling.

Promotion of Raf-1/ASK1 complex formation by corylin inhibits cell apoptosis in myocardial ischemia/reperfusion injury.

Effective treatment of myocardial ischemia-reperfusion (MIR) injury remains an unmet clinical need. Cardiomyocyte apoptosis is common at this stage and poses a significant risk. Corylin, a flavonoid compound extracted from Psoralea corylifolia L., has been shown to have anti-inflammatory, anticancer, and antiatherosclerotic properties. However, whether and how corylin affects MIR injury remain unclear. In this study, we explored the mechanism of corylin as a potent therapeutic agent for MI/R injury, using a left anterior descending (LAD) coronary artery ligation and oxygen-glucose deprivation and reperfusion (OGD/R) model in vivo and in vitro. TUNEL, Annexin-V/PI double staining,Ki67 immunohistochemistry, western blot analysis, and immunofluorescence were used to validate cell apoptosis level and Raf-1/ASK1 complex activity. The interaction between corylin and Raf-1/ASK1 complex was detected using molecular docking, corylin-Raf-1 binding assays, and coimmunoprecipitation (Co-IP). Moreover, TTC staining, echocardiography, HE staining, Masson trichrome staining and serological testing were performed to assess the cardioprotective effects of corylin in vivo. These findings showed that corylin reduces MIR injury-induced cardiomyocyte apoptosis and improves cardiac function. Mechanistically, corylin can interact with Raf-1 and promote the formation of the Raf-1/ASK1 complex, thus inhibiting cardiomyocyte apoptosis. In conclusion, our results demonstrate that corylin ameliorated cardiac dysfunction after MIR injury by reducing myocardial apoptosis.

Vagal-α7 nicotinic acetylcholine receptor signaling exacerbates influenza severity by promoting lung epithelial cell infection.

The vagus nerve circuit, operating through the alpha-7 nicotinic acetylcholine receptor (α7 nAChR), regulates the inflammatory response by influencing immune cells. However, the role of vagal-α7 nAChR signaling in influenza virus infection is unclear. In particular, does vagal-α7 nAChR signaling impact the infection of alveolar epithelial cells (AECs), the primary target cells of influenza virus? Here, we demonstrated a distinct role of α7 nAChR in type II AECs compared to its role in immune cells during influenza infection. We found that deletion of Chrna7 (encoding gene of α7 nAChR) in type II AECs or disruption of vagal circuits reduced lung influenza infection and protected mice from influenza-induced lung injury. We further unveiled that activation of α7 nAChR enhanced influenza infection through PTP1B-NEDD4L-ASK1-p38MAPK pathway. Mechanistically, activation of α7 nAChR signaling decreased p38MAPK phosphorylation during infection, facilitating the nuclear export of influenza viral ribonucleoproteins and thereby promoting infection. Taken together, our findings reveal a mechanism mediated by vagal-α7 nAChR signaling that promotes influenza viral infection and exacerbates disease severity. Targeting vagal-α7 nAChR signaling may offer novel strategies for combating influenza virus infections.

Therapeutic potential of ASK1 activators in cancer treatment: Current insights and future directions.

Apoptosis signal-regulated kinase 1 (ASK1) is a member of the mitogen-activated protein kinase kinase (MAP3K) family, whose activation and regulation are intricately associated with apoptosis. ASK1 is activated in response to oxidative stress, among other stimuli, subsequently triggering downstream JNK, p38 MAPK, and mitochondria-dependent apoptotic signaling, which participate in the initiation of tumor cell apoptosis induced by various stimuli. Research has shown that ASK1 plays a crucial role in the apoptosis of lung cancer, breast cancer, and liver cancer cells. Currently, the investigation of effective ASK1 activators is a hot topic in research on tumor cell apoptosis. Synthetic compounds such as human ß-defensin, triazolothiazide derivatives and heat shock protein 27 inhibitors; natural compounds such as quercetin, Laminarina japonica polysaccharide-1 peptide and theabrownin; and nanomedicines such as cerium oxide nanoparticles, magnetite FeO nanoparticles and silver nanoparticles can activate ASK1 and induce apoptosis in various tumor cells. This review extensively investigates the roles and activation mechanisms of ASK1, explores its impact on a variety of apoptotic signaling pathways, and discusses the potential therapeutic applications of various ASK1 activators in cancer treatment. In addition, this paper provides an in-depth discussion of the future development of this field and proposes a promising method for further research and clinical progress.

SDS3 regulates microglial inflammation by modulating the expression of the upstream kinase ASK1 in the p38 MAPK signaling pathway.

BACKGROUND: Microglia, the main innate immune cells in the central nervous system, are key drivers of neuroinflammation, which plays a crucial role in the pathogenesis of neurodegenerative diseases. The Sin3/histone deacetylase (HDAC) complex, a highly conserved multiprotein co-repressor complex, primarily performs transcriptional repression via deacetylase activity; however, the function of SDS3, which maintains the integrity of the complex, in microglia remains unclear. METHODS: To uncover the regulatory role of the transcriptional co-repressor SDS3 in microglial inflammation, we used chromatin immunoprecipitation to identify SDS3 target genes and combined with transcriptomics and proteomics analysis to explore expression changes in cells following SDS3 knocking down. Subsequently, we validated our findings through experimental assays. RESULTS: Our analysis revealed that SDS3 modulates the expression of the upstream kinase ASK1 of the p38 MAPK pathway, thus regulating the activation of signaling pathways and ultimately influencing inflammation. CONCLUSIONS: Our findings provide important evidence of the contributions of SDS3 toward microglial inflammation and offer new insights into the regulatory mechanisms of microglial inflammatory responses.

ABT­737 increases cisplatin sensitivity through the ROS­ASK1­JNK MAPK signaling axis in human ovarian cancer cisplatin­resistant A2780/DDP cells.

Ovarian cancer is a gynecological malignant tumor with the highest mortality rate, and chemotherapy resistance seriously affects patient therapeutic outcomes. It has been shown that the high expression of anti­apoptotic proteins Bcl­2 and Bcl­xL is closely related to ovarian cancer chemotherapy resistance. Therefore, reducing Bcl­2 and Bcl­xL expression levels may be essential for reversing drug resistance in ovarian cancer. ABT­737 is a BH3­only protein mimetic, which can effectively inhibit the expression of the anti­apoptotic proteins Bcl­xL and Bcl­2. Although it has been shown that ABT­737 can increase the sensitivity of ovarian cancer cells to cisplatin, the specific molecular mechanism remains unclear and requires further investigation. In the present study, the results revealed that ABT­737 can significantly increase the activation levels of JNK and ASK1 induced by cisplatin in A2780/DDP cells, which are cisplatin­resistant ovarian cancer cells. Inhibition of the JNK and ASK1 pathway could significantly reduce cisplatin cytotoxicity increased by ABT­737 in A2780/DDP cells, while inhibiting the ASK1 pathway could reduce JNK activation. In addition, it was further determined that ABT­737 could increase reactive oxygen species (ROS) levels in A2780/DDP cells induced by cisplatin. Furthermore, the inhibition of ROS could significantly reduce JNK and ASK1 activation and ABT­737­mediated increased cisplatin cytotoxicity in A2780/DDP cells. Overall, the current data identified that activation of the ROS­ASK1­JNK signaling axis plays an essential role in the ability of ABT­737 to increase cisplatin sensitivity in A2780/DDP cells. Therefore, upregulation the ROS­ASK1­JNK signaling axis is a potentially novel molecular mechanism by which ABT­737 can enhance cisplatin sensitivity of ovarian cancer cells. In addition, the present research can also provide new therapeutic strategies and new therapeutic targets for patients with cisplatin­resistant ovarian cancer with high Bcl­2/Bcl­xL expression patterns.

Ophiopogonin D alleviates acute lung injury by regulating inflammation via the STAT3/A20/ASK1 axis.

BACKGROUND: Acute lung injury (ALI) is characterized by acute pulmonary inflammatory infiltration. Alveolar epithelial cells (AECs) release numerous pro-inflammatory cytokines, which result in the pathological changes seen in ALI. Ophiopogonin D (OD), extracted from the roots of Ophiopogon japonicus (Thunb.) Ker Gawl. (Liliaceae), reduces inflammation; however, the efficacy of OD in ALI has not been reported and the underlying molecular mechanisms remain unclear. PURPOSE: This study investigated the anti-inflammatory effects of OD, as well as the underlying mechanisms, in AECs and a mouse ALI model. METHODS: Lipopolysaccharide (LPS) and tumor necrosis factor-α (TNF-α) were used to stimulate macrophages and A549 cells, and a mouse ALI model was established by intratracheal LPS administration. The anti-inflammatory effects and mechanisms of OD in the TNF-α-induced in vitro inflammation model was evaluated using real-time quantitative polymerase chain reaction qPCR), enzyme-linked immunosorbent assay (ELISA), western blotting, nuclear and cytoplasmic protein extraction, and immunofluorescence. The in vivo anti-inflammatory activity of OD was evaluated using hematoxylin and eosin staining, qPCR, ELISA, and western blotting. RESULTS: The bronchoalveolar lavage fluid and lung tissue of LPS-induced ALI mice exhibited increased TNF-α expression. TNF-α induced a significantly greater pro-inflammatory effect in AECs than LPS. OD reduced inflammation and mitogen-activated protein kinase (MAPK) and transcription factor p65 phosphorylation in vivo and in vitro and promoted signal transducer and activator of transcription 3 (STAT3) phosphorylation and A20 expression, thereby inducing apoptosis signal-regulating kinase 1 (ASK1) proteasomal degradation. CONCLUSION: OD exerts an anti-inflammatory effect by promoting STAT3-dependent A20 expression and ASK1 degradation. OD may therefore have therapeutic value in treating ALI and other TNF-α-related inflammatory diseases.

ASK1 activation in glial cells in post-mortem multiple sclerosis tissue.

Multiple sclerosis (MS), the leading cause of disability in young adults, is an inflammatory disease of the central nervous system characterized by localized areas of demyelination. Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein kinase kinase kinase that has been shown to be implicated in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. Interestingly, ASK1 signaling regulates glial cell interactions and drives neuroinflammation in EAE mice. To further investigate its clinical significance, in the present study, we examined the activation of ASK1 in the post-mortem brain of MS patients. ASK1 activation was found in active lesions of the corpus callosum in both microglia/macrophages and astrocytes. Moreover, ASK1 activation in astrocytes was higher than that in microglia/macrophages, which was in line with our findings in EAE mice. Our results suggest an important role of ASK1 in glial cells, indicating that ASK1 might be a good therapeutic target for MS.

Increasing expression of dual-specificity phosphatase 12 mitigates oxygen-glucose deprivation/reoxygenation-induced neuronal apoptosis and inflammation through inactivation of the ASK1-JNK/p38 MAPK pathway.

Dual-specificity phosphatase 12 (DUSP12) is abnormally expressed under various pathological conditions and plays a crucial role in the pathological progression of disorders. However, the role of DUSP12 in cerebral ischaemia/reperfusion injury has not yet been investigated. This study explored the possible link between DUSP12 and cerebral ischaemia/reperfusion injury using an oxygen-glucose deprivation/reoxygenation (OGD/R) model. Marked decreases in DUSP12 levels have been observed in cultured neurons exposed to OGD/R. DUSP12-overexpressed neurons were resistant to OGD/R-induced apoptosis and inflammation, whereas DUSP12-deficient neurons were vulnerable to OGD/R-evoked injuries. Further investigation revealed that DUSP12 overexpression or deficiency affects the phosphorylation of apoptosis signal-regulating kinase 1 (ASK1), c-Jun NH2-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) in neurons under OGD/R conditions. Moreover, blockade of ASK1 diminished the regulatory effect of DUSP12 deficiency on JNK and p38 MAPK activation. In addition, DUSP12-deficiency-elicited effects exacerbating neuronal OGD/R injury were reversed by ASK1 blockade. In summary, DUSP12 protects against neuronal OGD/R injury by reducing apoptosis and inflammation through inactivation of the ASK1-JNK/p38 MAPK pathway. These findings imply a neuroprotective function for DUSP12 in cerebral ischaemia/reperfusion injury.

The de-ubiquitinase UBQUITIN SPECIFIC PROTEASE 15 (UBP15) interacts with the SCF E3 complex adaptor ARABIDOPSIS SKP1 HOMOLOGUE 1 (ASK1) to regulate petal size and fertility in Arabidopsis thaliana.

Ubiquitination is a pivotal type of post-translational modification, which plays a far-reaching role in plant growth and development, as well as in the response of plants to stress. Just like the two sides of a coin, de-ubiquitination also plays an important role in plant life, which has been gradually discovered in recent years. Here, we demonstrate that the UBQUITIN SPECIFIC PROTEASE 15 (UBP15), which is a UBP-type de-ubiquitinase, interacts with the SCF E3 complex adaptor ARABIDOPSIS SKP1 HOMOLOGUE 1 (ASK1) and influences its protein stability to regulate plant fertility and petal size. The UBP15 is associated with the ASK1 physically, as verified by yeast-two-hybrid (Y2H) and protein pull-down in vitro assays. Disruption of ASK1 by a T-DNA insertion generates some abnormal phenotypes, such as low fertility and small petals. Genetic analysis shows that the UBP15 mutation enhances the low-fertility and small-petal phenotypes of ask1 mutant plants. By proteomic analysis, many types of proteins were identified as potential candidate downstream genes associated with the phenotypes of ubp15 ask1 double mutant plants. Taken together, these findings reveal a molecular relationship between ASK1 and UBP15 and their interaction in the regulation of petal size and fertility, which would benefit in-depth research about the ubiquitin-related pathway in plant physiological processes in the future.

Activation of stress-response genes by retrograde signaling-mediated destabilization of nuclear importin IMPα-9 and its interactor TPR2.

Stress-induced retrograde signal transmission from the plastids to the nucleus has long puzzled plant biologists. To address this, we performed a suppressor screen of the ceh1 mutant, which contains elevated 2-C-methyl-d-erythritol-2,4-cyclopyrophosphate (MEcPP) levels, and identified the gain-of-function mutant impα-9, which shows reversed dwarfism and suppressed expression of stress-response genes in the ceh1 background despite heightened MEcPP. Subsequent genetic and biochemical analyses established that the accumulation of MEcPP initiates an upsurge in Arabidopsis SKP1-like 1 (ASK1) abundance, a pivotal component in the proteasome degradation pathway. This increase in ASK1 prompts the degradation of IMPα-9. Moreover, we uncovered a protein-protein interaction between IMPα-9 and TPR2, a transcriptional co-suppressor and found that a reduction in IMPα-9 levels coincides with a decrease in TPR2 abundance. Significantly, the interaction between IMPα-9 and TPR2 was disrupted in impα-9 mutants, highlighting the critical role of a single amino acid alteration in maintaining their association. Disruption of their interaction results in the reversal of MEcPP-associated phenotypes. Chromatin immunoprecipitation coupled with sequencing analyses revealed that TPR2 binds globally to stress-response genes and suggested that IMPα-9 associates with the chromatin. They function together to suppress the expression of stress-response genes under normal conditions, but this suppression is alleviated in response to stress through the degradation of the suppressing machinery. The biological relevance of our discoveries was validated under high light stress, marked by MEcPP accumulation, elevated ASK1 levels, IMPα-9 degredation, reduced TPR2 abundance, and subsequent activation of a network of stress-response genes. In summary, our study collectively unveils fresh insights into plant adaptive mechanisms, highlighting intricate interactions among retrograde signaling, the proteasome, and nuclear transport machinery.

Abrogating PDK4 activates autophagy-dependent ferroptosis in breast cancer via ASK1/JNK pathway.

BACKGROUND: Targeting ferroptosis mediated by autophagy presents a novel therapeutic approach to breast cancer, a mortal neoplasm on the global scale. Pyruvate dehydrogenase kinase isozyme 4 (PDK4) has been denoted as a determinant of breast cancer metabolism. The target of this study was to untangle the functional mechanism of PDK4 in ferroptosis dependent on autophagy in breast cancer. METHODS: RT-qPCR and western blotting examined PDK4 mRNA and protein levels in breast cancer cells. Immunofluorescence staining appraised light chain 3 (LC3) expression. Fe (2 +) assay estimated total iron level. Relevant assay kits and C11-BODIPY (591/581) staining evaluated lipid peroxidation level. DCFH-DA staining assayed intracellular reactive oxygen species (ROS) content. Western blotting analyzed the protein levels of autophagy, ferroptosis and apoptosis-signal-regulating kinase 1 (ASK1)/c-Jun N-terminal kinase (JNK) pathway-associated proteins. RESULTS: PDK4 was highly expressed in breast cancer cells. Knockdown of PDK4 induced the autophagy of breast cancer cells and 3-methyladenine (3-MA), an autophagy inhibitor, countervailed the promoting role of PDK4 interference in ferroptosis in breast cancer cells. Furthermore, PDK4 knockdown activated ASK1/JNK pathway and ASK1 inhibitor (GS-4997) partially abrogated the impacts of PDK4 absence on the autophagy and ferroptosis in breast cancer cells. CONCLUSION: To sum up, deficiency of PDK4 activated ASK1/JNK pathway to stimulate autophagy-dependent ferroptosis in breast cancer.

Exploring novel indazole derivatives as ASK1 inhibitors: Design, synthesis, biological evaluation and docking studies.

Apoptosis signal regulated kinase 1 (ASK1, MAP3K5) is a member of the mitogen activated protein kinase (MAPK) signaling pathway, involved in cell survival, differentiation, stress response, and apoptosis. ASK1 kinase inhibition has become a promising strategy for the treatment of Non-alcoholic steatohepatitis (NASH) disease. A series of novel ASK1 inhibitors with indazole scaffolds were designed and synthesized, and their ASK1 kinase activities were evaluated. The System Structure Activity Relationship (SAR) study discovered a promising compound 33c, which has a strong inhibitory effect on ASK1. Noteworthy observations included a discernible reduction in lipid droplets within LO2 cells stained with Oil Red O, coupled with a decrease in LDL, CHO, and TG content within the NASH model cell group. Mechanistic inquiries revealed that compound 33c could inhibit the protein expression levels of the upregulated ASK1-p38/JNK signaling pathway in TNF-α treated HGC-27 cells and regulate apoptotic proteins. In summary, these findings suggest that compound 33c may be valuable for further research as a potential candidate compound against NASH.

Co-targeting ASK1 and THRß synergistically improves steatohepatitis and fibrosis in a MASH animal model.

PURPOSE: Metabolic dysfunction-associated steatohepatitis (MASH) is a liver disease that has gained widespread attention globally. Unfortunately, there is no approved treatment for this condition yet. However, recent research has identified Apoptosis signal-regulating kinase 1 (ASK1) and thyroid hormone receptor-ß (THR-ß) as potential targets for treating MASH. Although the individual effects of these two targets have been studied, their combinatory effect has not been well defined. Therefore, further research is needed to investigate the potential benefits of targeting both ASK1 and THR-ß for treating MASH. METHODS: We established a MASH model using the HFHFrC diet (high fat, high fructose, and cholesterol) and carbon tetrachloride (CCL4). Forty mice were evenly assigned to four groups: vehicle, GS4997 (an ASK1 inhibitor), MGL3196 (a THRß agonist), GS4997+ MGL3196 combination (combo). The drugs were administered for 8 weeks, after which the mice were sacrificed for serum biochemical tests, liver TG and TC evaluation, liver histopathological study, and gene expression validation. RESULTS: GS4997 and MGL3196, when used in combination, have been shown to have synergistic effects on various parameters. Firstly, they synergistically reduced body weight and liver body weight ratio. Secondly, this combination also synergistically lowered AST and TC. Thirdly, synergistic effects were also observed in liver TG and TC reduction. Fourthly, we further confirmed that GS4997 mildly improved liver inflammation, ballooning, and fibrosis, but exhibited incredible histopathological efficacy when combined with MGL3196. Finally, this combinatory effect can be interpreted by synergistically regulating lipid-related genes such as Dio1, Ctp1-α, and Cat, inflammation-related genes such as Il-6, Il-8, and Mcp-1, and fibrosis-related genes such as Tgf-ß, Col1α1, and Col6α3. CONCLUSION: GS4997 and MGL3196, when used in combination, have been shown to have a comprehensive effect on MASH by synergistically regulating lipid, inflammation, and fibrosis-related gene expression through co-targeting ASK1 and THRß.