Loss of Transcriptional Repression by BCL6 Confers Insulin Sensitivity in the Setting of Obesity

Abstract

Summary: Accumulation of visceral adiposity is directly linked to the morbidity of obesity, while subcutaneous body fat is considered more benign. We have identified an unexpected role for B cell lymphoma 6 (BCL6), a critical regulator of immunity, in the developmental expansion of subcutaneous adipose tissue. In adipocyte-specific knockout mice (Bcl6AKO), we found that Bcl6 deletion results in strikingly increased inguinal, but not perigonadal, adipocyte size and tissue mass in addition to marked insulin sensitivity. Genome-wide RNA expression and DNA binding analyses revealed that BCL6 controls gene networks involved in cell growth and fatty acid biosynthesis. Using deuterium label incorporation and comprehensive adipokine and lipid profiling, we discovered that ablation of adipocyte Bcl6 enhances subcutaneous adipocyte lipogenesis, increases levels of adiponectin and fatty acid esters of hydroxy fatty acids (FAHFAs), and prevents steatosis. Thus, our studies identify BCL6 as a negative regulator of subcutaneous adipose tissue expansion and metabolic health. : Senagolage et al. identify BCL6 as a key regulator of body fat distribution. BCL6 directly represses fatty acid biosynthetic and growth genes in adipocytes. Mice constitutively lacking adipocyte Bcl6 exhibit expansion of their subcutaneous adipose tissue, enhanced insulin sensitivity, and protection from hepatic steatosis. Keywords: obesity, BCL6, BCL-6, repressor, adipocyte, hypertrophy, subcutaneous fat, insulin sensitivity, lipogenesis, adipose tissue, FAHFA, fatty acid esters of hydroxy fatty acids, PAHSA, adiponectin, ceramide