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Aberrant differentiation of keratinocytes disrupts the skin barrier and causes a series of skin diseases. However, the molecular basis of keratinocyte differentiation is still poorly understood. In the present study, we examined the expression of C7ORF41 using tissue microarrays by immunohistochemistry and found that C7ORF41 is specifically expressed in the basal layers of skin epithelium and its expression is gradually decreased during keratinocytes differentiation. Importantly, we corroborated the pivotal role of C7ORF41 during keratinocyte differentiation by C7ORF41 knockdown or overexpression in TPA-induced Hacat keratinocytes. Mechanismly, we first demonstrated that C7ORF41 inhibited keratinocyte differentiation mainly through formatting a complex with IKKα in the cytoplasm, which thus blocked the nuclear translocation of IKKα. Furthermore, we also demonstrated that inhibiting the PKCα/ERK signaling pathway reversed the reduction in C7ORF41 in TPA-induced keratinocytes, indicating that C7ORF41 expression could be regulated by upstream PKCα/ERK signaling pathway during keratinocyte differentiation. Collectively, our study uncovers a novel regulatory network PKCα/ERK/C7ORF41/IKKα during keratinocyte differentiation, which provides potential therapeutic targets for skin diseases.

Nonalcoholic fatty liver disease (NAFLD) is a prevalent and complex disease that confers a high risk of severe liver disorders. Despite such public and clinical health importance, very few effective therapies are currently available for NAFLD. We report a protective function and the underlying mechanism of dual-specificity phosphatase 14 (DUSP14) in NAFLD and related metabolic disorders. Insulin resistance, hepatic lipid accumulation, and concomitant inflammatory responses, key pathological processes involved in NAFLD development, were significantly ameliorated by hepatocyte-specific DUSP14 overexpression (DUSP14-HTG) in high-fat diet (HFD)-induced or genetically obese mouse models. By contrast, specific DUSP14 deficiency in hepatocytes (DUSP14-HKO) aggravated these pathological alterations. We provided mechanistic evidence that DUSP14 directly binds to and dephosphorylates transforming growth factor β-activated kinase 1 (TAK1), resulting in the reduced activation of TAK1 and its downstream signaling molecules c-Jun N-terminal kinase 1 (JNK), p38, and nuclear factor kappa B NF-κB. This effect was further evidenced by the finding that inhibiting TAK1 activity effectively attenuated the deterioration of glucolipid metabolic phenotype in DUSP14-HKO mice challenged by HFD administration. Furthermore, we identified that both the binding domain and the phosphatase activity of DUSP14 are required for its protective role against hepatic steatosis, because interruption of the DUSP14-TAK1 interaction abolished the mitigative effects of DUSP14. CONCLUSION Hepatocyte DUSP14 is required for maintaining hepatic metabolic homeostasis and for suppressing inflammation, a novel function that relies on constraining TAK1 hyperactivation. (Hepatology 2018;67:1320-1338).

Tripartite motif 8 (TRIM8), an E3 ligase ubiquitously expressed in various cells, is closely involved in innate immunity. However, its role in nonalcoholic steatohepatitis is largely unknown. Here, we report evidence that TRIM8 is a robust enhancer of steatohepatitis and its complications induced by a high-fat diet or a genetic deficiency (ob/ob). Using gain-of-function and loss-of-function approaches, we observed dramatic exacerbation of insulin resistance, hepatic steatosis, inflammation, and fibrosis by hepatocyte-specific TRIM8 overexpression, whereas deletion or down-regulation of TRIM8 in hepatocytes led to a completely opposite phenotype. Furthermore, investigations of the underlying mechanisms revealed that TRIM8 directly binds to and ubiquitinates transforming growth factor-beta-activated kinase 1, thus promoting its phosphorylation and the activation of downstream c-Jun N-terminal kinase/p38 and nuclear factor κB signaling. Importantly, the participation of TRIM8 in human nonalcoholic fatty liver disease and nonalcoholic steatohepatitis was verified on the basis of its dramatically increased expression in the livers of these patients, suggesting a promising development of TRIM8 disturbance for the treatment of nonalcoholic steatohepatitis-related metabolic disorders. Conclusion The E3 ligase TRIM8 is a potent regulator that exacerbates steatohepatitis and metabolic disorders dependent on its binding and ubiquitinating capacity on transforming growth factor-beta-activated kinase 1. (Hepatology 2017;65:1492-1511).

Nonalcoholic fatty liver disease (NAFLD) is an expanding health problem worldwide. Although many studies have made great efforts to elucidate the pathogenesis of NAFLD, the molecular basis remains poorly understood. Here, we showed that hepatic C7ORF41, a critical regulator of innate immune response, was markedly decreased in diet or genetic-induced NAFLD model. We also demonstrated that C7ORF41 overexpression significantly ameliorated hepatic inflammation and lipid accumulation in palmitic acid (PA)-treated hepatocytes, whereas C7ORF41 knockdown showed the opposite effects. Mechanistically, we found the anti-inflammatory role of C7ORF41 was attributed to the suppression of NF-κB p65-mediated induction of inflammatory cytokines. Moreover, we demonstrated that the suppression of C7ORF41 expression in hepatocytes is due to JNK activation, which promotes c-Jun-mediated transcriptional repression of C7ORF41. In conclusion, our findings suggested that a c-Jun/C7ORF41/NF-κB regulatory network controls the inflammatory response and lipid accumulation in NAFLD and may benefit the development of novel and promising therapeutic targets for NAFLD.

ZNF300 plays an important role in the regulation of HBV-related hepatocellular carcinoma. However, little is known about the role of ZNF300 in lipid metabolism and NAFLD. In the present study, we observed that ZNF300 expression was markedly decreased in free fatty acid (FFA)-induced fatty liver. Overexpressed ZNF300 alleviated hepatic lipid accumulation, whereas knockdown of ZNF300 enhanced the FFA-induced lipid accumulation. Investigations of the underlying mechanisms revealed that ZNF300 directly binds to and regulates the PPARα expression, thus promoting fatty acid oxidation. Furthermore, bisulfite pyrosequencing PCR (BSP) analysis identified the hypermethylation status of ZNF300 gene in FFA-treated hepatocytes. Importantly, the suppression of ZNF300 could be blocked by DNA methyltransferase inhibitor (5-azadC) or DNMT3a-siRNA. These results suggested that ZNF300 plays an important role in hepatic lipid metabolism via PPARα promoting fatty acid oxidation and this effect might be blocked by DNMT3a-mediated methylation of ZNF300. Therefore, in addition to ZNF300 expression levels, the methylation status of this gene also has a potential as a prognostic biomarker.

To study the function of ZNF300 in the megakaryocytes differentiation and proliferation.Public data analysis of ZNF300 expression and megakaryocyte culture were used to reveal the correlation of ZNF300 expression with leukemia and megakaryocyte differetniation; ZNF300 overexpression was mediated by lentiviral or retroviral infection, and the differentiation and proliferation of K562 cells and primary mouse bone marrow cells to magekaryocytes were measured by flow cytometry, MTT assay and colony-forming test; the ZNF300 subcellular localization was tested by separating cytosolic and nuclear extracts combined with Western blotting. The dual-luciferase assay and ChIP-qPCR were used to study ZNF300 target gene.ZNF300 expression upregulation correlated with megakaryoyte differentiation; over-expression of ZNF300 promoted CD41 and CD61 expression, inhibited cell cycle progress, and could reduce colony-forming unit. The ZNF300 locolized in nuclear and regulated C-MYC expression.ZNF300 promotes megakaryocyte differentiation.

Background Accumulating evidence demonstrates that the KRAB-ZNFs involve in various biological processes. As a typical member of KRAB-ZNFs, dysregulation of ZNF300 contributes to multiple pathologies such as leukemia and cancer. However, mechanisms underlying ZNF300 tight regulation and its pathophysiological function remain largely unknown. Methods The effect of ZNF300ZFR on gene transcriptional activity was measured by Dual luciferase reporter system. ChIP-PCR assay were performed to detect the enrichment of ZNF300 protein and H3K9Ac in the ZNF300 gene. Co-immunoprecipitation assays followed by western blot were performed to detect the interaction between ZNF300 and KAP1. The DNA methylation in the ZNF300 gene promoter was analyzed by BSP. ZNF300 function on K562 cell differentiation was analyzed by flow cytometry. Results In this study, we found that the zinc finger domain-encoding region (ZFR) of ZNF300 functioned as a repressor possibly by mediating DNA methylation and ZNF300 bound to its ZNF300ZFR, suggesting a potential auto-inhibition mechanism. To support this, DNA methylation inhibition upregulated ZNF300 expression and ZNF300 overexpression inhibited endogenous ZNF300 expression. More importantly, DNA methylation inhibition restored megakaryocyte differentiation in K562 cells suppressed by ZNF300 downregulation, suggesting an important role of DNA methylation in ZNF300 function. Interestingly, ZNF300 knockdown restored global H3K9Ac that was reduced in K562 cells undergoing megakaryocyte differentiation. Conclusions Our study revealed novel features of ZNF300 that possibly mediate its regulation and function by modulating epigenetic modifications.

Background: Cardiac hypertrophy and its resultant heart failure are among the most common causes of mortality worldwide. Abnormal protein degradation, especially the impaired lysosomal degradation of large organelles and membrane proteins, is involved in the progression of cardiac hypertrophy. However, the underlying mechanisms have not been fully elucidated. Methods: We investigated cardiac transmembrane BAX inhibitor motif containing 1 (TMBIM1) mRNA and protein expression levels in samples from patients with heart failure and mice with aortic banding (AB)–induced cardiac hypertrophy. We generated cardiac-specific Tmbim1 knockout mice and cardiac-specific Tmbim1 -overexpressing transgenic mice and then challenged them with AB surgery. We used microarray, confocal image, and coimmunoprecipitation analyses to identify the downstream targets of TMBIM1 in cardiac hypertrophy. Tmbim1 / Tlr4 double-knockout mice were generated to investigate whether the effects of TMBIM1 on cardiac hypertrophy were Toll-like receptor 4 (TLR4) dependent. Finally, lentivirus-mediated TMBIM1 overexpression in a monkey AB model was performed to evaluate the therapeutic potential of TMBIM1. Results: TMBIM1 expression was significantly downregulated on hypertrophic stimuli in both human and mice heart samples. Silencing cardiac Tmbim1 aggravated AB-induced cardiac hypertrophy. This effect was blunted by Tmbim1 overexpression. Transcriptome profiling revealed that the TLR4 signaling pathway was disrupted dramatically by manipulation of Tmbim1 . The effects of TMBIM1 on cardiac hypertrophy were shown to be dependent on TLR4 in double-knockout mice. Fluorescent staining indicated that TMBIM1 promoted the lysosome-mediated degradation of activated TLR4. Coimmunoprecipitation assays confirmed that TMBIM1 directly interacted with tumor susceptibility gene 101 via a PTAP motif and accelerated the formation of multivesicular bodies that delivered TLR4 to the lysosomes. Finally, lentivirus-mediated TMBIM1 overexpression reversed AB-induced cardiac hypertrophy in monkeys. Conclusions: TMBIM1 protects against pathological cardiac hypertrophy through promoting the lysosomal degradation of activated TLR4. Our findings reveal the central role of TMBIM1 as a multivesicular body regulator in the progression of pathological cardiac hypertrophy, as well as the role of vesicle trafficking in signaling regulation during cardiac hypertrophy. Moreover, targeting TMBIM1 could be a novel therapeutic strategy for treating cardiac hypertrophy and heart failure.

Previously, we reported that ZNF300 might play a role in leukemogenesis. In this study, we further investigated the function of ZNF300 in K562 cells undergoing differentiation. We found that ZNF300 upregulation in K562 cells coincided with megakaryocytic differentiation induced by phorbol-12-myristate-13-acetate (PMA) or erythrocytic differentiation induced by cytosine arabinoside (Ara-C), respectively. To further test whether ZNF300 upregulation promoted differentiation, we knocked down ZNF300 and found that ZNF300 knockdown effectively abolished PMA-induced megakaryocytic differentiation, evidenced by decreased CD61 expression. Furthermore, Ara-C-induced erythrocytic differentiation was also suppressed in ZNF300 knockdown cells with decreased γ-globin expression and CD235a expression. These observations suggest that ZNF300 may be a critical factor controlling distinct aspects of K562 cells. Indeed, ZNF300 knockdown led to increased cell proliferation. Consistently, ZNF300 knockdown cells exhibited an increased percentage of cells at S phase accompanied by decreased percentage of cells at G0/G1 and G2/M phase. Increased cell proliferation was further supported by the increased expression of cell proliferation marker PCNA and the decreased expression of cell cycle regulator p15 and p27. In addition, MAPK/ERK signaling was significantly suppressed by ZNF300 knockdown. These findings suggest a potential mechanism by which ZNF300 knockdown may impair megakaryocytic and erythrocytic differentiation.