Mutations in the BSCL2 gene underlie human type 2 Berardinelli-Seip congenital lipodystrophy (BSCL2) disease. Global Bscl2–/– mice recapitulate human BSCL2 lipodystrophy and results in the development of insulin resistance and hypertrophic cardiomyopathy. The pathological mechanisms underlying the development of lipodystrophy and cardiomyopathy in BSCL2 are controversial. Here we report that Bscl2–/– mice develop cardiac hypertrophy because of increased basal IGF1 receptor–mediated (IGF1R-mediated) PI3K/AKT signaling. Bscl2–/– hearts exhibited increased adipose triglyceride lipase (ATGL) protein stability and expression causing drastic reduction of glycerolipids. Excessive fatty acid oxidation was overt in Bscl2–/– hearts, partially attributing to the hyperacetylation of cardiac mitochondrial proteins. Intriguingly, pharmacological inhibition or genetic inactivation of ATGL could rescue adipocyte differentiation and lipodystrophy in Bscl2–/– cells and mice. Restoring a small portion of fat mass by ATGL partial deletion in Bscl2–/– mice not only reversed the systemic insulin resistance, but also ameliorated cardiac protein hyperacetylation, normalized cardiac substrate metabolism, and improved contractile function. Collectively, our study uncovers pathways underlying lipodystrophy-induced cardiac hypertrophy and metabolic remodeling and pinpoints ATGL as a downstream target of BSCL2 in regulating the development of lipodystrophy and its associated cardiomyopathy.
Hongyi Zhou, Xinnuo Lei, Yun Yan, Todd Lydic, Jie Li, Neal L. Weintraub, Huabo Su, Weiqin Chen
BSCL2 deficiency reduces intramyocellular glycerolipids and elevates ATGL stability and expression in the heart.