Mechanism of Storage and Synthesis of Fatty Acids and Triglycerides in White Adipocytes

Abstract

Mechanism of storage and synthesis of fatty acids and triglycerides in white adipocytes Lipid storage in adipocytes is essential for energy homeostasis and has probably played a major role in the survival of our species in periods of food shortage. In adipose tissue, fatty acids are stored as triglycerides formed from a backbone of glycerol which are esterified three fatty acids. In a lean young adult human, the mass of triglycerides stored represents about 10–20 kilograms i.e. 90 000–180 000 kcal. The origin of the fatty acids stored as triglycerides is for a major part the diet. Triglycerides after their intestinal hydrolysis and resynthesis in the enterocytes are delivered as chylomicrons into the circulation. Fatty acids in adipocytes can also originate from the de novo synthesis of fatty acids from glucose in the liver (lipogenesis) delivered as “Very Low density Lipoproteins” (VLDL) into the circulation, or from lipogenesis in the adipocyte itself. Whatever their origin, exogenous or endogenous, free fatty acids are activated into acyl-CoA and esterified to finally reach the triglyceride droplet. In this review, we address the process of fatty acids delivery to the adipocytes from lipoproteins (chylomicrons and VLDL) and the specific role of lipoprotein lipase, the uptake of fatty acids by the adipocyte and their activation, their de novo synthesis and finally their esterification into triglycerides.