ApoAIV

ApoAIV, or apolipoprotein A-IV, is a vertebrate apolipoprotein involved in lipid transport and metabolism. It is synthesized mainly by enterocytes in the small intestine and is secreted with chylomicrons into the lymphatic system and bloodstream during fat absorption. Plasma levels of ApoAIV rise after meals rich in fat, reflecting increased intestinal production and lipoprotein assembly.

ApoA-IV is a member of the apolipoprotein A family and is associated with triglyceride-rich lipoproteins, such as chylomicrons, as well as HDL particles. Its proposed roles include facilitation of intestinal lipid absorption and lipoprotein assembly, modulation of postprandial lipemia, and participation in lipoprotein remodeling in circulation.

Beyond lipid metabolism, ApoA-IV has been implicated in energy and glucose regulation. Experimental evidence suggests a role as a satiety signal, potentially influencing appetite and glucose homeostasis, though human data are not definitive. The idea of anti-atherogenic effects has been proposed, but these effects remain uncertain and not yet established clinically.

Genetics and clinical aspects: The APOA4 gene encodes ApoA-IV. Genetic variants have been linked in some populations to differences in triglyceride responses to fat intake and to obesity risk, but findings are inconsistent and the precise clinical significance is unclear.

In summary, ApoA-IV is a meal-responsive apolipoprotein associated with circulating lipoproteins, contributing to lipid handling and potentially influencing metabolic regulation, with ongoing research to clarify its physiological and clinical roles.