Project description:Regulation of alternative splicing (AS) is crucial for gene expression and enables a single transcript to yield multiple isoforms that increase transcriptome and proteome diversity. Dysregulated AS has been linked to the development of non-alcoholic fatty liver diseases (NAFLD). However, the splicing factors involved in hepatic homeostasis and their functional mechanisms remain to be further characterized. Here, we report that spliceosome component Usp39 plays a critical role in the regulation of hepatocyte lipid homeostasis. We found that Usp39 expression is downregulated in hepatic tissues of NAFLD and non-alcoholic steatohepatitis (NASH) subjects. We observed increased lipid accumulation, spontaneous steatosis and impaired autophagy, lipophagy in particular, in mice with hepatocyte-specific Usp39 deletion. Combined analysis of RIP-seq and RNA-seq data revealed that Usp39 regulates AS of several autophagy-related genes including Hsf1. More specifically, deletion of Usp39 resulted in alternative 5’ splice site selection of exon 6 in Hsf1 and consequently reduced expression. Hsf1 was also found to be downregulated in NAFLD/NASH mice and patients. Importantly, overexpression of Hsf1 restored lipophagy, attenuated lipid accumulation and alleviated NASH caused by Usp39 deficiency. Taken together, our findings indicate that Usp39-mediated AS is crucial for sustaining lipophagy and lipid homeostasis in the liver.
Project description:High-grade serous ovarian carcinoma is the most lethal type of gynecologic malignancy.Emerging evidences have suggested the vital roles of splicing factor in the human cancers. RNA splicing pathways was found excessive activated in HGSOC. USP39 was one of overexpressed splicing factor in HGSOC. However, the biological function and concrete regulatory mechanism of USP39 in ovarian cancer remain unclear. In this study, we investigate the oncogenic roles of the splicing factor USP39 in HGSOC through facilitated the growth speed and invasion of ovarian cancer cells.Elevated USP39 expression levels, based on immunohistochemistry staining, were associated with poor survival in HGSOC patients. In order to investigate the binding peaks of USP39 in ovarian cancer,we performed RIP-seq in A2780 cells with Flag-USP39 overexpression.
Project description:High-grade serous ovarian carcinoma is the most lethal type of gynecologic malignancy.Emerging evidences have suggested the vital roles of splicing factor in the human cancers. RNA splicing pathways was found excessive activated in HGSOC. USP39 was one of overexpressed splicing factor in HGSOC. However, the biological function and concrete regulatory mechanism of USP39 in ovarian cancer remain unclear. In this study, we investigate the oncogenic roles of the splicing factor USP39 in HGSOC through facilitated the growth speed and invasion of ovarian cancer cells.Elevated USP39 expression levels, based on immunohistochemistry staining, were associated with poor survival in HGSOC patients. Since many RNA-binding proteins showed DNA-binding ability , we performed ChIP-seq in A2780 cells with Flag-USP39 overexpression in order to detect the bindng of USP39 to DNA and POLR2A was used as a positive control.
Project description:High-grade serous ovarian carcinoma is the most lethal type of gynecologic malignancy.Emerging evidences have suggested the vital roles of splicing factor in the human cancers. RNA splicing pathways was found excessive activated in HGSOC. USP39 was one of overexpressed splicing factor in HGSOC. However, the biological function and concrete regulatory mechanism of USP39 in ovarian cancer remain unclear. In this study, we investigate the oncogenic roles of the splicing factor USP39 in HGSOC through facilitated the growth speed and invasion of ovarian cancer cells.Elevated USP39 expression levels, based on immunohistochemistry staining, were associated with poor survival in HGSOC patients. In order to investigate the regulatory mechanism of USP39 in ovarian cancer,we performed RNA-seq in A2780 cells with USP39 knock down compared with control in three repeat. HMGA2 was identified as USP39 target gene because of different expression and downregulated splicing efficiency.
Project description:Regulation of alternative splicing (AS) is crucial for gene expression and enables a single transcript to yield multiple isoforms that increase transcriptome and proteome diversity. Dysregulated AS has been linked to the development of non-alcoholic fatty liver diseases (NAFLD). However, the splicing factors involved in hepatic homeostasis and their functional mechanisms remain to be further characterized. Here, we report that spliceosome component Usp39 plays a critical role in the regulation of hepatocyte lipid homeostasis. We found that Usp39 expression is downregulated in hepatic tissues of NAFLD and non-alcoholic steatohepatitis (NASH) subjects. We observed increased lipid accumulation, spontaneous steatosis and impaired autophagy, lipophagy in particular, in mice with hepatocyte-specific Usp39 deletion. Combined analysis of RIP-seq and RNA-seq data revealed that Usp39 regulates AS of several autophagy-related genes including Hsf1. More specifically, deletion of Usp39 resulted in alternative 5’ splice site selection of exon 6 in Hsf1 and consequently reduced expression. Hsf1 was also found to be downregulated in NAFLD/NASH mice and patients. Importantly, overexpression of Hsf1 restored lipophagy, attenuated lipid accumulation and alleviated NASH caused by Usp39 deficiency. Taken together, our findings indicate that Usp39-mediated AS is crucial for sustaining lipophagy and lipid homeostasis in the liver.
