The Regulation of Triacylglycerol Metabolism and Lipoprotein Lipase Activity. Issue 10 (8th June 2022) - Wen, Yi
Abstract: Triacylglycerol (TG) metabolism is tightly regulated to maintain a pool of TG within circulating lipoproteins that can be hydrolyzed in a tissue‐specific manner by lipoprotein lipase (LPL) to enable the delivery of fatty acids to adipose or oxidative tissues as needed. Elevated serum TG concentrations, which result from a deficiency of LPL activity or, more commonly, an imbalance in the regulation of tissue‐specific LPL activities, have been associated with an increased risk of atherosclerotic cardiovascular disease through multiple studies. Among the most critical LPL regulators are the angiopoietin‐like (ANGPTL) proteins ANGPTL3, ANGPTL4, and ANGPTL8, and a number of different apolipoproteins including apolipoprotein A5 (ApoA5), apolipoprotein C2 (ApoC2), and apolipoprotein C3 (ApoC3). These ANGPTLs and apolipoproteins work together to orchestrate LPL activity and therefore play pivotal roles in TG partitioning, hydrolysis, and utilization. This review summarizes the mechanisms of action, epidemiological findings, and genetic data most relevant to these ANGPTLs and apolipoproteins. The interplay between these important regulators of TG metabolism in both fasted and fed states is highlighted with a holistic view toward understanding key concepts and interactions. Strategies for developing safe and effective therapeutics to reduce circulating TG by selectively targeting these ANGPTLs and apolipoproteins are also discussed. Abstract : Angiopoietin‐like proteins (ANGPTL) and apolipoproteins (Apo) orchestrate triacylglycerol (TG) metabolism. After feeding, insulin increases circulating ANGPTL3/8 and localized ANGPTL4/8 in adipose tissue. Hepatic ApoA5 secretion decreases, leaving ANGPTL3/8 unbound by ApoA5 and able to potently inhibit lipoprotein lipase (LPL) in muscle. TG are hydrolyzed in adipose tissue where their fatty acids (FA) are re‐esterified.