A novel autophagy gene beclin 2 in the prevention of type 2 diabetes and obesity

The objective of this K99/R00 Pathway to Independence Award application is to study the functions and mechanisms of a novel autophagy gene beclin 2 in the prevention of type 2 diabetes and obesity. Type 2 diabetes is a metabolic disorder characterized by the inability of pancreatic β cells to compensate for body insulin resistance, often accompanied by obesity. However, the pathogenesis of obesity-related type 2 diabetes is incompletely understood. Recently, both activation of autophagy and downregulation of the cannabinoid receptor 1 (CB1R) signaling have been implicated in preventing diabetes/obesity. During my previous mentored training, I discovered and cloned a novel mammalian-specific autophagy gene belonging to the Beclin (coiled-coil, myosin-like BCL2-interacting protein) family, beclin 2, and my preliminary data showed that the disruption of beclin 2 has striking effects on autophagy, and lysosomal trafficking and turnover of a specific subset of G protein-coupled receptors including CB1R. In this application, I will study the mechanisms of Beclin 2 in autophagy, CB1R signaling and metabolic regulation, and will also investigate the crosstalk between the two lysosomal degradation pathways regulated by Beclin 2: Aim 1 characterizes the molecular mechanism(s) of Beclin 2 in the regulation of autophagy in vitro and in vivo, through biochemical methods and structure-function studies of protein-protein interactions of Beclin 2; Aim 2 investigates the function and mechanisms by which Beclin 2 regulates CB1R degradation and signaling, and study whether this function of Beclin 2 interrelates with its role in autophagy; and Aim 3 studies the in vivo functions of Beclin 2 in maintaining insulin sensitivity and preventing obesity in response to regular diet and high-fat diet challenge, using a knockout mouse model (beclin 2-/-) and a conditional knockout mouse model (beclin 2flox/flox) that I have recently generated. Together, these studies will shed light on the role and cellular mechanisms of autophagy in metabolic regulation, and help understand the impact of therapeutic manipulation of autophagy in metabolic diseases.