Melanoma differentiation-associated protein 5 prevents cardiac hypertrophy via apoptosis signal-regulating kinase 1-c-Jun N-terminal kinase/p38 signaling

Pathological cardiac hypertrophy (CH) is driven by maladaptive changes in myocardial cells in response to pressure overload or other stimuli. CH has been identified as a significant risk factor for the development of various cardiovascular diseases, ultimately resulting in heart failure. Melanoma differentiation-associated protein 5 (MDA5), encoded by interferon-induced with helicase C domain 1 (IFIH1), is a cytoplasmic sensor that primarily functions as a detector of double-stranded ribonucleic acid (dsRNA) viruses in innate immune responses; however, its role in CH pathogenesis remains unclear. Thus, the aim of this study was to examine the relationship between MDA5 and CH using cellular and animal models generated by stimulating neonatal rat cardiomyocytes with phenylephrine and by performing transverse aortic constriction on mice, respectively. MDA5 expression was upregulated in all models. MDA5 deficiency exacerbated myocardial pachynsis, fibrosis, and inflammation in vivo, whereas its overexpression hindered CH development in vitro. In terms of the underlying molecular mechanism, MDA5 inhibited CH development by promoting apoptosis signal-regulating kinase 1 (ASK1) phosphorylation, thereby suppressing c-Jun N-terminal kinase/p38 signaling pathway activation. Rescue experiments using an ASK1 activation inhibitor confirmed that ASK1 phosphorylation was essential for MDA5-mediated cell death. Thus, MDA5 protects against CH and is a potential therapeutic target.

ASK1-K716R reduces neuroinflammation and white matter injury via preserving blood-brain barrier integrity after traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is a significant worldwide public health concern that necessitates attention. Apoptosis signal-regulating kinase 1 (ASK1), a key player in various central nervous system (CNS) diseases, has garnered interest for its potential neuroprotective effects against ischemic stroke and epilepsy when deleted. Nonetheless, the specific impact of ASK1 on TBI and its underlying mechanisms remain elusive. Notably, mutation of ATP-binding sites, such as lysine residues, can lead to catalytic inactivation of ASK1. To address these knowledge gaps, we generated transgenic mice harboring a site-specific mutant ASK1 Map3k5-e (K716R), enabling us to assess its effects and elucidate potential underlying mechanisms following TBI.

METHODS

We employed the CRIPR/Cas9 system to generate a transgenic mouse model carrying the ASK1-K716R mutation, aming to investigate the functional implications of this specific mutant. The controlled cortical impact method was utilized to induce TBI. Expression and distribution of ASK1 were detected through Western blotting and immunofluorescence staining, respectively. The ASK1 kinase activity after TBI was detected by a specific ASK1 kinase activity kit. Cerebral microvessels were isolated by gradient centrifugation using dextran. Immunofluorescence staining was performed to evaluate blood-brain barrier (BBB) damage. BBB ultrastructure was visualized using transmission electron microscopy, while the expression levels of endothelial tight junction proteins and ASK1 signaling pathway proteins was detected by Western blotting. To investigate TBI-induced neuroinflammation, we conducted immunofluorescence staining, quantitative real-time polymerase chain reaction (qRT-PCR) and flow cytometry analyses. Additionally, immunofluorescence staining and electrophysiological compound action potentials were conducted to evaluate gray and white matter injury. Finally, sensorimotor function and cognitive function were assessed by a battery of behavioral tests.

RESULTS

The activity of ASK1-K716R was significantly decreased following TBI. Western blotting confirmed that ASK1-K716R effectively inhibited the phosphorylation of ASK1, JNKs, and p38 in response to TBI. Additionally, ASK1-K716R demonstrated a protective function in maintaining BBB integrity by suppressing ASK1/JNKs activity in endothelial cells, thereby reducing the degradation of tight junction proteins following TBI. Besides, ASK1-K716R effectively suppressed the infiltration of peripheral immune cells into the brain parenchyma, decreased the number of proinflammatory-like microglia/macrophages, increased the number of anti-inflammatory-like microglia/macrophages, and downregulated expression of several proinflammatory factors. Furthermore, ASK1-K716R attenuated white matter injury and improved the nerve conduction function of both myelinated and unmyelinated fibers after TBI. Finally, our findings demonstrated that ASK1-K716R exhibited favorable long-term functional and histological outcomes in the aftermath of TBI.

CONCLUSION

ASK1-K716R preserves BBB integrity by inhibiting ASK1/JNKs pathway in endothelial cells, consequently reducing the degradation of tight junction proteins. Additionally, it alleviates early neuroinflammation by inhibiting the infiltration of peripheral immune cells into the brain parenchyma and modulating the polarization of microglia/macrophages. These beneficial effects of ASK1-K716R subsequently result in a reduction in white matter injury and promote the long-term recovery of neurological function following TBI.

Intronic miR-140-5p contributes to beta-cypermethrin-mediated testosterone decline

Beta-cypermethrin (β-CYP), a widely-used pyrethroid pesticide, is considered to have anti-androgenic effects and could impair male reproduction. To ascertain whether MAPK pathways, DNA methyltransferases (DNMTs), and miRNAs played pleiotropic roles in β-CYP-mediated testicular dysfunction, Sprague-Dawley rats and Leydig cells were employed in this study. Results showed that plasma testosterone levels were declined, testicular histomorphology and ultrastructures were abnormally altered, and Leydig cell functions were damaged after β-CYP exposure. JNK and p38/MAPK pathways were inactivated, accompanied by the decrease in c-Jun and Sp1 expressions. Specific activators/inhibitors of MAPK pathways and Co-IP demonstrated that DNMT3α was synergistically regulated by JNK/p38 pathways. The activity, mRNA and protein expressions of DNMT3α were all reduced by β-CYP. β-CYP induced expressions of intronic miR-140-5p and its host gene Wwp2, and then overexpressed miR-140-5p suppressed steroidogenic StAR, P450scc, and 3β-HSD by directly targeting SF-1. SF-1 silencing/overexpression, ChIP, and qPCR indicated that SF-1 modulated positively StAR, P450scc, and 3β-HSD expressions by directly binding to their promoter regions. Intriguingly, 5α-reductase expressions were downregulated after β-CYP exposure. Collectively, β-CYP has the anti-androgenic feature and the DNMT3α/miR-140-5p/SF-1 cascade co-regulated by JNK/p38 functions critically in β-CYP-caused testosterone declines. The downregulation of 5α-reductases may be a potential compensatory mechanism of the organism.

CircPrkcsh, a circular RNA, contributes to the polarization of microglia towards the M1 phenotype induced by spinal cord injury and acts via the JNK/p38 MAPK pathway

Spinal cord injury (SCI) is a complex pathological change that includes primary SCI and gradually evolves into secondary SCI. Accumulating evidence demonstrates that circular RNAs (circRNAs) are involved in the pathology of a variety of neurological diseases and injuries. However, the characteristics and function of circRNAs in SCI have yet to be elucidated. Although previous research demonstrated that circPrkcsh induces astrocytes to produce inflammatory factors and chemokines, the precise function and mechanism of circPrkcsh in microglia after SCI remains unknown. In this study, we constructed a mouse model of SCI by applying a SCI impactor. Quantitative Real-time PCR and Fluorescence in situ hybridization analysis revealed that circPrkcsh was upregulated in the microglia of SCI mice when compared to sham-operated mice. Gain- or loss-of-function experiments and in vivo assays further indicated that circPrkcsh promotes microglia M1 polarization both in vivo and in vitro. Furthermore, bioinformatics analysis, dual-luciferase assays, and RNA immunoprecipitation assays, confirmed that circPrkcsh serves as a competing endogenous RNA (ceRNA) to promote the expression of MEKK1 mRNA by sponging miR-488. Double knockout rescue experiments further showed that circPrkcsh regulates the MEKK1/JNK/p38 MAPK pathway via miR-488. Our research provides a better understanding of the mechanism of circPrkcsh in SCI and demonstrates that the circPrkcsh/miR-488/Mekk1 axis is a promising regulatory method for the treatment of SCI.

KDELR2 knockdown synergizes with temozolomide to induce glioma cell apoptosis through the CHOP and JNK/p38 pathways

BACKGROUND

The C-terminal tetrapeptide Lys-Asp-Glu-Leu receptors (KDELRs) are transmembrane proteins that regulate ER stress (ERS) response, growth, differentiation, and immune responses. There is an association between KDELR2and promotion of glioblastoma tumorigenesis. The aim of the present study was to explore the functional mechanism of KDELR2 in glioma and during response to chemotherapy to temozolomide (TMZ).

METHODS

The expression of KDELR2 in glioma tissues and cells was evaluated by immunohistochemistry, western blot and RT-qPCR assay. Then role of KDELR2 was demonstrated by CCK8, colony formation, flow cytometry and Hochest 33258 assays. The expression of genes (ATF4, ATF6, PERK, eIF2-α, GRP78 and CHOP) in U373 cells was evaluated by RT-qPCR. The protein expression of genes (cleaved caspase 3, caspase 3, cleaved PARP, PARP, Bax, Bcl-2, JNK, p-JNK, p38, p-p38, ATF4, ATF6, XBP-1s, PERK, p-PERK, GRP78 and CHOP) was measured by western blot assay.

RESULTS

The expression of KDELR2 was upregulated in high-grade gliomas tissues. KDELR2 knockdown suppressed cell proliferation but increased cell apoptosis. Further, Knockdown of KDELR2 also activated the ER stress (ERS)-dependent CHOP pathway, and resulted in increased levels of phosphorylated c-Jun N-terminal kinase (JNK) and p38. Moreover, the combination of KDELR2 knockdown and TMZ application showed a synergistic cytotoxic effect in U373 cells through the ERS-dependent CHOP and JNK/p38 pathways.

CONCLUSIONS

KDELR2 knockdown induces apoptosis and sensitizes glioma cells to TMZ, which is mediated by the ERS-dependent CHOP and JNK/p38 pathways.

Activation of JNK and p38 MAPK Mediated by ZDHHC17 Drives Glioblastoma Multiforme Development and Malignant Progression

Rationale: Glioblastoma multiforme (GBM) almost invariably gain invasive phenotype with limited therapeutic strategy and ill-defined mechanism. By studying the aberrant expression landscape of gliomas, we find significant up-regulation of p-MAPK level in GBM and a potent independent prognostic marker for overall survival. DHHC family was generally expressed in glioma and closely related to the activation of MAPK signaling pathway, but its role and clinical significance in GBM development and malignant progression are yet to be determined.

Method: Bioinformatics analysis, western blotting and immunohistochemistry (IHC) were performed to detect the expression of ZDHHC17 in GBM. The biological function of ZDHHC17 was demonstrated by a series of in vitro and in vivo experiments. Pharmacological treatment, flow cytometry, Transwell migration assay, Co- Immunoprecipitation and GST pulldown were carried out to demonstrate the potential mechanisms of ZDHHC17.

Results: ZDHHC17 is up-regulated and coordinated with MAPK activation in GBM. Mechanistically, ZDHHC17 interacts with MAP2K4 and p38/JNK to build a signaling module for MAPK activation and malignant progression. Notably, the ZDHHC17-MAP2K4-JNK/p38 signaling module contributes to GBM development and malignant progression by promoting GBM cell tumorigenicity and glioma stem cell (GSC) self-renewal. Moreover, we identify a small molecule, genistein, as a specific inhibitor to disrupt ZDHHC17-MAP2K4 complex formation for GBM cell proliferation and GSC self-renewal. Moreover, genistein, identified herein as a lead candidate for ZDHHC17-MAP2K4 inhibition, demonstrated potential therapeutic effect in patients with ZDHHC17-expressing GBM.

Conclusions: Our study identified disruption of a previously unrecognized signaling module as a target strategy for GBM treatment, and provided direct evidence of the efficacy of its inhibition in glioma using a specific inhibitor.

Differential roles of ATF-2 in survival and DNA repair contributing to radioresistance induced by autocrine soluble factors in A549 lung cancer cells

Radioresistance is one of the obstacles to the effective radiotherapy for non-small cell lung cancer. Soluble factors in the tumour microenvironment are often implicated in radioresistance but the underpinning mechanism(s) remain largely elusive. We herein studied the wholesome effect of autocrine cytokines and growth factors in the form of self-conditioned medium (CM) on the radiosensitivity of A549 cells. A549 cells grown in CM exhibited radioresistance which was associated with increased survival and DNA repair. CM induced pro-survival pathways through increased intracellular cAMP and phosphorylation of JNK and p38. Downstream to JNK/p38 signalling, ATF-2 phosphorylated at Thr69/71 was accompanied with its increased transcriptional activity in CM treated cells. Pre-treatment with cAMP inhibitor and silencing of ATF-2 abrogated the CM-induced survival. Interestingly, in cells treated with CM followed by radiation, ATF-2 was found to be switched over from transcription factor to DNA damage response protein. In CM treated cells, after γ-radiation p-ATF-2(Thr69/71) and subsequently the transcriptional activity of ATF-2 were declined with simultaneous rise in p-ATF-2(Ser490/498). Immunoprecipitation/immunoblotting and inhibitor studies showed that phosphorylation of ATF-2 at Ser490/498 was mediated by ATM. Moreover, p-ATF-2(Ser490/498) was found to be co-localised with γ-H2AX in DNA repair foci in CM-treated cells. The DNA repair activity of ATF-2 was assisted with higher activity MRN complex in cells grown in CM. Our study revealed that, autocrine soluble factors regulate dual but differential role of ATF-2 as a transcription factor or DNA repair protein, which collectively culminate in radioresistance of A549 cells.