Poster abstracts
Poster number 6 submitted by Waqar Arif
Hepatocyte-Specific Deletion Of A Splicing Regulatory Protein Causes Spontaneous And Severe Nonalcoholic Steatohepatitis In Mice
Waqar Arif (Departments of Biochemistry and Medical Biochemistry, College of Medicine, University of Illinois at Urbana-Champaign), Gandar Dhatar (Department of Biochemistry, University of Illinois at Urbana-Champaign), Qinyu Hao (Department of Cellular and Developmental Biology, University of Illinois at Urbana-Champaign), Jian Ma (Departments of Bioengineering and Cellular and Developmental Biology, University of Illinois at Urbana-Champaign), K V Prasanth (Department of Cellular and Developmental Biology, University of Illinois at Urbana-Champaign), Auinash Kalsotra (Departments of Biochemistry and Medical Biochemistry, College of Medicine, Institute of Genomic Biology, University of Illinois at Urbana-Champaign)
Abstract:
Non-Alcoholic Steatohepatitis (NASH) is emerging as one of the most common liver disease in the American population. It is a metabolic disorder in which fat accumulation within the liver (steatosis) is associated with inflammation, hepatic injury and cirrhosis without significant consumption of alcohol. A recent study examining SNPs in patients with NASH revealed a significant association for pathways involved in mRNA splicing. To further investigate factors involved in NASH pathology, we screened various RNA splicing factors for changes in expression in fatty liver mice models. To our surprise we found a specific downregulation of SRSF1, a highly conserved pre-mRNA splicing factor. This trend was also verified in human fatty liver patient samples which showed a striking downregulation of SRSF1 as well.
To study the function of SRSF1 in liver we created a hepatocyte-specific knockout (HKO) using Cre-loxP technology. Histological and serum analyses of these mice revealed spontaneous and progressive NASH-like liver injury including steatosis, inflammation, and fibrosis. We hypothesized that lack of SRSF1 in hepatocytes results in misregulated splicing and expression of specific transcripts leading to the development of NASH. In order to identify the underlying transcriptome defects, we performed a high-resolution RNA-Seq on livers of five-week old wildtype and SRSF1 HKO mice. Computational analysis of the data revealed hundreds of genes with altered splicing and expression many of which are related to fatty acid metabolism, lipid peroxidation and inflammation. In addition to splicing regulation, SRSF1 has also been shown to regulate the composition of nuclear speckles. Astonishingly, we observe a significant loss of MALAT1 localization to speckles in SRSF1 HKO hepatocytes. Taken together our results demonstrate that SRSF1 is essential for maintaining transcriptome integrity in hepatocytes and that impairment of its activity induces spontaneous NASH pathology in mice.
Keywords: Splice Regulation, SRSF1, Liver Disease