FXR adapts hepatic mitochondrial function to increased substrate oxidation in patients with obesity

Abstract

Metabolic pressure shifts signaling pathways of nuclear receptors, including the bile acid receptor FXR, which are sensitive to nutritional inputs. We performed an FXR ChIP-seq-centered multiomic analysis of liver biopsy samples from individuals with or without obesity, who were treated with either placebo or the FXR agonist obeticholic acid, to define metabolic adaptions of FXR signaling pathways. FXR occupied substantially more DNA binding sites in individuals with obesity, and FXR activation by OCA robustly changed the transcriptional output. Integration of ChIP-seq and RNA-seq data showed that mitochondrial function and substrate oxidation were the top metabolic pathways selectively modulated by FXR activation in individuals with obesity. FXR activation restored compromised substrate oxidation by enhancing β-oxidation and oxidative phosphorylation along with antagonizing ROS production. In line with this, the amount of reduced glutathione in patients with obesity normalized after OCA treatment. In summary, FXR signaling profoundly differs in patients with obesity, consisting of changes in DNA binding profiles and transcriptional programs, which enhance energy substrate utilization in this patient cohort.