Nuclear Receptor Corepressors Non-Canonically Drive Glucocorticoid Receptor-Dependent Activation of Hepatic Gluconeogenesis [ATAC-Seq]

Nuclear receptor corepressors (NCORs) function in multiprotein complexes containing histone deacetylase 3 (HDAC3). In the liver, loss of HDAC3 causes a marked hepatosteatosis largely due to derepression of genes involved in lipid metabolism. Here we show that adult loss of both NCOR1 and 2 (dKO) in hepatocytes phenocopies the hepatomegalic fatty liver phenotype. In addition, dKO livers exhibited a dramatic reduction in glycogen storage and gluconeogenic gene expression that was not observed with hepatic KO of individual NCORs nor HDAC3, resulting in profound fasting hypoglycemia. This surprising HDAC3-independent activation function of NCOR1/2 was due to an unexpected loss of chromatin accessibility upon deletion of NCORs that prevented glucocorticoid receptor binding and stimulatory effect on gluconeogenic genes. These studies reveal an unanticipated, non-canonical activation function of NCORs that is required for metabolic health. Overall design: Analysis of chromatin accessibility in HNF4a+ hepatocytes isolated from control and NCOR1/2 dKO livers.