Cyanidin-3-O-β-glucoside regulates fatty acid metabolism via an AMP-activated protein kinase-dependent signaling pathway in human HepG2 cells

Anthocyanin Cy-3-g increased cellular AMPK activity in a calmodulin kinase kinase dependent manner. Furthermore, Cy-3-g substantially induced AMPK downstream target ACC phosphorylation and inactivation, and then decreased malonyl CoA contents, leading to stimulation of CPT-1 expression and significant increase of fatty acid oxidation in HepG2 cells. These effects of Cy-3-g are largely abolished by pharmacological and genetic inhibition of AMPK.This study demonstrates that Cy-3-g regulates hepatic lipid homeostasis via an AMPK-dependent signaling pathway. Targeting AMPK activation by anthocyanin may represent a promising approach for the prevention and treatment of obesity-related nonalcoholic fatty liver disease.Nonalcoholic fatty liver disease (NAFLD) is a serious consequence of obesity, increasing the risk of liver cancer or cirrhosis [1]. The origin of this disease is unknown and probably multifactorial. Nevertheless, because impaired lipid metabolism is recognized as an associate and/or promoting mediator of the disease, management of hepatic metabolic disorders becomes an essential strategy for prevention and treatment of obesity-related NAFLD [2].AMP-activated protein kinase (AMPK) is a key sensor of cellular energy status and it is also recognized as a major regulator of liver and whole body lipid homeostasis [3]. AMPK activation in the liver results in the phosphorylation and inactivation of acetyl-CoA carboxylase (ACC), a direct AMPK substrate, leading to decreased conversion of acetyl-CoA to malonyl CoA [4]. AMPK activation also results in phosphorylation and activation of malonyl CoA decarboxylase (MCD), resulting in further lowering of malonyl CoA levels. Malonyl CoA allosterically inhibits carnitine palmitoyl-CoA transferase 1 (CPT-1), the enzyme responsible for transport of long chain acyl-CoAs into mitochondria for oxidation. Additionally, as malonyl CoA is required for de novo synthesis of fatty acids, decreased malonyl CoA leads to a reduction in he