Project description:Regulation of RNA processing contributes profoundly to tissue development and physiology. The serine-arginine-rich splicing factor 1 (SRSF1) is essential for hepatocyte function and survival. Although SRSF1 is mainly known for its many roles in mRNA metabolism, it is also crucial for maintaining genome stability. We show that acute liver damage in the setting of targeted SRSF1 deletion in mice is primarily mediated by the excessive formation of deleterious RNA–DNA hybrids (R-loops), which induce DNA damage. Combining hepatocyte-specific transcriptome, proteome, and RNA binding analyses, we demonstrate that widespread genotoxic stress following SRSF1 depletion results in global inhibition of mRNA transcription and protein synthesis, leading to impaired metabolism and trafficking of lipids. Accumulation of lipids in SRSF1-deficient hepatocytes is quickly followed by necroptotic cell death, inflammation, and fibrosis, resulting in NASH-like liver pathology. This pathogenesis is recapitulated in SRSF1-depleted human liver cancer cells illustrating a conserved and fundamental role for SRSF1 in preserving genome integrity and tissue homeostasis. This data set contains a proteomic comparison of hepatocytes from wild type vs. acute knockout of SRSF1. The acute knockout was generated by injecting 8-week-old SRSF1 fl/fl mice with a viral vector expressing Cre under the control of the liver-specific thyroxine binding globulin (TBG) promoter (AAV8-TBG-iCre). Controls were generated by injecting AAV8-TBG-GFP viral vector. The hepatocytes were isolated 2 weeks post injection.
Project description:RNA from primary hepatocyte cultures from three 3-month-old SRSF1HKO mice compared to RNA from three 3-month-old WT mice for changes in exon utilization and gene expression. SRSF1 KO vs. WT, three replicates each.
Project description:We report that the decreased expression of mitochondrial genes we observe in hepatocyte-specific Nampt knockout mice is normalized in primary hepatocytes, and that hepatocyte isolations causes major changes to the hepatocyte transcriptome for both knockouts and wildtype mice.
Project description:RNA sequencing of primary hepatocytes from Control and and hepatocyte-specific Mettl3 knockout with ALB-Cre (Mettl3 cKO) mice after Actinomycin D treatment.
Project description:Post-transcriptional gene regulatory mechanisms (PTGRM) contribute profoundly to liver development and physiology. Alternative splicing is one of the earliest mechanisms of gene regulation acting on nascently transcribed mRNA. This process is mediated by a large class of proteins known as splicing factors. SRSF1 is a canonical splicing factor with roles in both constitutive and alternative splicing. While its biochemical activities have been studied extensively, its role in tissue physiology are not well defined. In this study we investigate the role of SRSF1 in liver physiology using hepatocyte-specific knock-out mice models. Hepatocyte-specific knock-out of SRSF1 was achieved in two ways; 1) SRSF1 floxed mice were crossed with AlbCre transgenic mice and 2) SRSF1 floxed mice were injected with AAV8-TBG-iCre viral vector. The latter model allowed for investigating acute changes in hepatocyte upon ablation of SRSF1. Both models exhibit acute liver injury with severe cellular damage, inflammation and lipid accumulation. Utilizing high-throughput transcriptome profiling on purified hepatocytes, we find acute loss of SRSF1 triggers activation of the p53 pathway and splicing dysregulation of genes involved in mRNA metabolism. Continuous hepatic injury in this model eventually triggers a regenerative response resulting in the upregulation of genes involved in proliferation and repopulation of the tissue parenchyma.
Project description:Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. Persistent NAFLD can progress to nonalcoholic steatohepatitis (NASH) with inflammation and fibrosis, which predisposes patients to cirrhosis and hepatocellular carcinoma. CCAAT/enhancer-binding protein alpha (CEBPA) is a transcription factor that modulates glycolipid homeostasis, cell differentiation and tumor progression. MTL-CEBPA, a first-in-human small activating RNA therapeutic, has been used to overexpress CEBPA and treat hepatocellular carcinoma by targeting myeloid cells in clinical trials. However, whether and how hepatocyte-specific CEBPA modulates NASH are unknown. Here we found that CEBPA expression was inhibited in the livers of high-fat, high-cholesterol, and high-fructose diet (HFCFD)-fed mice, NASH patients and palmitic/oleic acid-treated primary hepatocytes. Liver-specific Cebpa knockout mice (Cebpa-dLiv) and liver-specific tamoxifen-inducible ERT2-Cre mice (Cebpa-dLiv-ERT2) were then generated. Both Cebpa-dLiv and Cebpa-dLiv-ERT2 mice (treated with tamoxifen) developed enhanced NASH and fibrosis compared to control mice. Global transcriptome analyses demonstrated hepatic secreted phosphoprotein 1 (Spp1) encoding the fibrosis-promoting factor SPP1, was markedly induced by hepatocyte CEBPA knockout in HFCFD-fed mice. Consistently, hepatic SPP1 was upregulated by NASH and negatively correlated with CEBPA expression in humans. Hepatocyte loss of CEBPA enhanced hepatic SPP1 expression and serum SPP1 levels both at the early and late stage of NASH in mice. CEBPA-knockout primary hepatocytes released more SPP1 to the culture medium than wild-type mouse hepatocytes, resulting in enhanced fibrogenesis of hepatic stellate cells, a phenotype that was rescued by the Spp1 shRNA. Hepatocyte-directed AAV8-deliverey of Spp1 shRNA rescued the fibrosis in HFCFD-fed Cebpa-dLiv mice. Mechanistically, CEBPA overexpression reduced, while CEBPA knockout enhanced, SPP1 expression in primary hepatocytes in vitro. The Spp1 promoter had functional CEBPA response elements, while CEBPA modulated histone acetylation to restrict SPP1 expression in a novel feedback loop. Furthermore, overexpression of CEBPA in hepatocytes with AAV8-TBG-CEBPA, inhibited hepatic SPP1 expression and reduced fibrosis in HFCFD-fed wild-type mice. This study demonstrates a novel hepatocyte CEBPA-SPP1 axis involved in modulating NASH fibrosis that supports hepatocyte CEBPA as an anti-NASH target.
Project description:Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. Persistent NAFLD can progress to nonalcoholic steatohepatitis (NASH) with inflammation and fibrosis, which predisposes patients to cirrhosis and hepatocellular carcinoma. CCAAT/enhancer-binding protein alpha (CEBPA) is a transcription factor that modulates glycolipid homeostasis, cell differentiation and tumor progression. MTL-CEBPA, a first-in-human small activating RNA therapeutic, has been used to overexpress CEBPA and treat hepatocellular carcinoma by targeting myeloid cells in clinical trials. However, whether and how hepatocyte-specific CEBPA modulates NASH are unknown. Here we found that CEBPA expression was inhibited in the livers of high-fat, high-cholesterol, and high-fructose diet (HFCFD)-fed mice, NASH patients and palmitic/oleic acid-treated primary hepatocytes. Liver-specific Cebpa knockout mice (Cebpa-dLiv) and liver-specific tamoxifen-inducible ERT2-Cre mice (Cebpa-dLiv-ERT2) were then generated. Both Cebpa-dLiv and Cebpa-dLiv-ERT2 mice (treated with tamoxifen) developed enhanced NASH and fibrosis compared to control mice. Global transcriptome analyses demonstrated hepatic secreted phosphoprotein 1 (Spp1) encoding the fibrosis-promoting factor SPP1, was markedly induced by hepatocyte CEBPA knockout in HFCFD-fed mice. Consistently, hepatic SPP1 was upregulated by NASH and negatively correlated with CEBPA expression in humans. Hepatocyte loss of CEBPA enhanced hepatic SPP1 expression and serum SPP1 levels both at the early and late stage of NASH in mice. CEBPA-knockout primary hepatocytes released more SPP1 to the culture medium than wild-type mouse hepatocytes, resulting in enhanced fibrogenesis of hepatic stellate cells, a phenotype that was rescued by the Spp1 shRNA. Hepatocyte-directed AAV8-deliverey of Spp1 shRNA rescued the fibrosis in HFCFD-fed Cebpa-dLiv mice. Mechanistically, CEBPA overexpression reduced, while CEBPA knockout enhanced, SPP1 expression in primary hepatocytes in vitro. The Spp1 promoter had functional CEBPA response elements, while CEBPA modulated histone acetylation to restrict SPP1 expression in a novel feedback loop. Furthermore, overexpression of CEBPA in hepatocytes with AAV8-TBG-CEBPA, inhibited hepatic SPP1 expression and reduced fibrosis in HFCFD-fed wild-type mice. This study demonstrates a novel hepatocyte CEBPA-SPP1 axis involved in modulating NASH fibrosis that supports hepatocyte CEBPA as an anti-NASH target.
Project description:Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. Persistent NAFLD can progress to nonalcoholic steatohepatitis (NASH) with inflammation and fibrosis, which predisposes patients to cirrhosis and hepatocellular carcinoma. CCAAT/enhancer-binding protein alpha (CEBPA) is a transcription factor that modulates glycolipid homeostasis, cell differentiation and tumor progression. MTL-CEBPA, a first-in-human small activating RNA therapeutic, has been used to overexpress CEBPA and treat hepatocellular carcinoma by targeting myeloid cells in clinical trials. However, whether and how hepatocyte-specific CEBPA modulates NASH are unknown. Here we found that CEBPA expression was inhibited in the livers of high-fat, high-cholesterol, and high-fructose diet (HFCFD)-fed mice, NASH patients and palmitic/oleic acid-treated primary hepatocytes. Liver-specific Cebpa knockout mice (Cebpa-dLiv) and liver-specific tamoxifen-inducible ERT2-Cre mice (Cebpa-dLiv-ERT2) were then generated. Both Cebpa-dLiv and Cebpa-dLiv-ERT2 mice (treated with tamoxifen) developed enhanced NASH and fibrosis compared to control mice. Global transcriptome analyses demonstrated hepatic secreted phosphoprotein 1 (Spp1) encoding the fibrosis-promoting factor SPP1, was markedly induced by hepatocyte CEBPA knockout in HFCFD-fed mice. Consistently, hepatic SPP1 was upregulated by NASH and negatively correlated with CEBPA expression in humans. Hepatocyte loss of CEBPA enhanced hepatic SPP1 expression and serum SPP1 levels both at the early and late stage of NASH in mice. CEBPA-knockout primary hepatocytes released more SPP1 to the culture medium than wild-type mouse hepatocytes, resulting in enhanced fibrogenesis of hepatic stellate cells, a phenotype that was rescued by the Spp1 shRNA. Hepatocyte-directed AAV8-deliverey of Spp1 shRNA rescued the fibrosis in HFCFD-fed Cebpa-dLiv mice. Mechanistically, CEBPA overexpression reduced, while CEBPA knockout enhanced, SPP1 expression in primary hepatocytes in vitro. The Spp1 promoter had functional CEBPA response elements, while CEBPA modulated histone acetylation to restrict SPP1 expression in a novel feedback loop. Furthermore, overexpression of CEBPA in hepatocytes with AAV8-TBG-CEBPA, inhibited hepatic SPP1 expression and reduced fibrosis in HFCFD-fed wild-type mice. This study demonstrates a novel hepatocyte CEBPA-SPP1 axis involved in modulating NASH fibrosis that supports hepatocyte CEBPA as an anti-NASH target.
Project description:Background and Aims: The activation of stimulator of interferon genes (STING) and NOD-like receptors protein 3 (NLRP3) inflammasomes-mediated pyroptosis signaling pathways represent two distinct central mechanisms in liver disease. However, the interconnection between these two pathways and the epigenetic regulation of the STING-NLRP3 axis in hepatocyte pyroptosis during liver fibrosis remain unknown and is the focus of this study. Approach and Results: Liver fibrosis was induced in Sting knockout, Gasdermin D (Gsdmd) knockout mice, and in mice with hepatocyte-specific Nlrp3 deletion. RNA-sequencing, metabolomics, epigenetic compound screening system, and chromatin immunoprecipitation were utilized. STING and NLRP3 inflammasome signaling pathways were activated in cirrhotic livers but were suppressed by Sting knockout. Sting knockout also ameliorated hepatic pyroptosis, inflammation, and fibrosis in the murine cirrhotic model. In vitro, STING induced pyroptosis in primary murine hepatocytes via activating the NLRP3 inflammasome. H3K4-specific histone methyltransferase WD repeat-containing protein 5 (WDR5) and DOT1-like histone H3K79 methyltransferase (DOT1L) were identified to regulate NLRP3 expression in STING-overexpressed AML12 hepatocytes. WDR5/DOT1L-mediated histone methylation enhanced interferon regulatory transcription factor 3 (IRF3) binding to the Nlrp3 promoter and promoted STING-induced Nlrp3 transcription in hepatocytes. The RNA-sequencing and metabolomics analysis in murine livers and primary hepatocytes showed that metabolic reprogramming might participate in NLRP3-mediated hepatocyte pyroptosis and liver fibrosis. Moreover, hepatocyte-specific Nlrp3 deletion and downstream Gsdmd knockout attenuated hepatic pyroptosis, inflammation, and fibrosis in murine cirrhotic models. Conclusions: This study describes a novel epigenetic mechanism by which the STING-WDR5/DOT1L/IRF3-NLRP3 signaling pathway enhances hepatocyte pyroptosis and hepatic inflammation in liver fibrosis.
Project description:Regulation of RNA processing contributes profoundly to tissue development and physiology. Here, we report that serine-arginine-rich splicing factor 1 (SRSF1) is essential for hepatocyte function and survival. Although SRSF1 is mainly known for its many roles in mRNA metabolism, it is also crucial for maintaining genome stability. We show that acute liver damage in the setting of targeted SRSF1 deletion in mice is primarily mediated by the excessive formation of deleterious RNA-DNA hybrids (R-loops), which induce DNA damage. Combining hepatocyte-specific transcriptome, proteome, and RNA binding analyses, we demonstrate that widespread genotoxic stress following SRSF1 depletion results in global inhibition of mRNA transcription and protein synthesis, leading to impaired metabolism and trafficking of lipids. Accumulation of lipids in SRSF1-deficient hepatocytes is quickly followed by necroptotic cell death, inflammation, and fibrosis, resulting in NASH-like liver pathology. This pathogenesis is recapitulated in SRSF1-depleted human liver cancer cells illustrating a conserved and fundamental role for SRSF1 in preserving genome integrity and tissue homeostasis. Thus, our study uncovers how accumulation of detrimental R-loops impedes hepatocellular gene expression, triggering metabolic derangements and liver failure.