Role of GATA4 in liver lipid metabolism To address the growing problem of non-alcoholic fatty liver disease (NAFLD), we need to understand the mechanisms regulating hepatic metabolism. Using high-throughput sequencing technologies including Assay for Transposase-Accessible Chromatin Sequencing (ATAC-Seq), we discovered a novel transcriptional regulator of liver metabolism: GATA4. This transcription factor is known for its crucial role in the development of many tissues, including liver; however, its role in adult liver metabolism is unknown. Our ATAC-Seq and RNA-Seq results show that GATA4 activity is increased in livers of refed mice compared to fasted mice, especially at the enhancers of lipid metabolism genes. Therefore, we hypothesized that GATA4 in adult liver regulates lipid metabolism, particularly in the fasting vs. refeeding response. To test this hypothesis, we assessed the effect of loss of Gata4 in adult liver by measuring gene expression via RNA-Seq and metabolic outcomes using a conditional knockout model (Gata4KO). Expression of cholesterol and triglyceride metabolism pathway genes were downregulated by the loss of Gata4 in the liver. Downregulated genes were also enriched for liver LXR ChIP-Seq targets. Gata4KO mice showed reduced plasma cholesterol and increased liver cholesterol compared to control. In contrast, Gata4 overexpression in liver led to a decrease in liver cholesterol. Collectively, these studies show that Gata4 regulates hepatic cholesterol homeostasis and allow us to paint a more complete picture of regulation of liver lipid metabolism.