Biochemical Characterization of Lipoprotein Lipase

Elevated triglycerides levels are an independent risk factor for the development of cardiovascular and metabolic diseases. Approximately one third of the American population suffers from hypertriglyceridemia. Lipoprotein lipase (LPL) is the rate-limiting enzyme for the hydrolysis of triglycerides from triglyceride rich lipoproteins (TRLs), which circulate in the blood. LPL also promotes clearance of circulating triglycerides by catalyzing the uptake of TRL remnant particles into the liver. For both its role in catalysis and lesser recognized role in lipoprotein uptake, LPL is an attractive therapeutic target for reducing circulating triglyceride levels and the subsequent risk of cardiovascular disease. Studies to understand LPL function have thus far been limited by protein yields, particularly for human LPL. This thesis focuses on work undertaken to better understand the elements that contribute to LPL’s successful function. First, I focused on pinpointing the benefit of a known, gain-of-function mutation, LPLS447X. LPLS447X is used in LPL gene therapy, but until now, there had been no clear mechanistic explanation for its gain-of-function. I next describe a new method for measuring LPL interactions and dynamics, using total internal reflection fluorescence microscopy to monitor single molecules of LPL. Finally, I conclude with a discussion of the ways these developments are moving the field forward.Doctor of Philosoph