Dr. Gregory Graf
Dr. Graf's laboratory's research focus is on the relationships between obesity and changes in lipid and lipoprotein metabolism that link obesity to cardiovascular diseases and diabetes. Our work largely centers on pathways that promote the active elimination of cholesterol from the body in a process termed “Reverse Cholesterol Transport”. Currently available therapies target cholesterol synthesis and absorption to reduce plasma cholesterol and lower the risk cardiovascular disease. However, an emerging body of work suggests that the flux of cholesterol through lipoproteins (LDL and HDL) is more relevant to cardiovascular disease than their absolute levels in plasma. In addition, research from our lab and others suggests that cholesterol in the liver may play an active role in the development of non-alcoholic fatty liver disease, a common complication of obesity. A transport protein complex called ABCG5 ABCG8, or G5G8 for short, is expressed in both the liver and intestine and represents the major route for cholesterol elimination from the body. We have recently shown that the loss of this transporter worsens the development of fatty liver disease and that acutely increasing its levels can restore some aspects of liver function in a mouse model of obesity and fatty liver disease. Our data also suggests that the function of this pump is altered in the setting of insulin resistance and fatty liver. However, little is known about the mechanisms that govern these changes and the extent to which these changes affect the progression of disease. The goal of this project is to determine how this pump is regulated in the liver such that therapeutics can be developed to accelerate cholesterol elimination in the treatment of both cardiovascular and liver disease. The second project focuses on the role of the intestine in cholesterol elimination. Classically, we think of the small intestine as an absorptive organ that provides the body with the nutrients extracted from our diets. However, it is clear that this organ is also important in cholesterol elimination and that other pathways independent of G5G8 contribute to sterol excretion. The goal of this project is to identify proteins within this alternate pathway and determine whether these are amenable to pharmaceutical development.