Functional characterization of two single nucleotide polymorphisms of acyl-coenzyme A:cholesterol acyltransferase 2

Background: Acyl-coenzyme A:cholesterol acyltransferase 2 (ACAT2) plays a critical role in the formation of cholesteryl esters from cholesterol and fatty acids, and is a potential target for treating hypercholesterolemia. We recently reported the significant effects of two human ACAT2 gene polymorphisms, 41A>G (Glu(14)Gly, rs9658625) and 734C>T (Thr(254)Ile, rs2272296), on plasma lipid levels and coronary artery disease susceptibility in a case-control association study. In the present study, we evaluated the possible biological influence of the two polymorphism using two approaches.

Methods: In the first approach, the functional impact of the two polymorphisms was predicted in-silico using available web-based software, and in the second approach, the varying functions of the two polymorphisms were characterized in in vitro experiments, using ACAT2-deficient AC-29 cells.

Results: Our results show that the enzymatic activity of mutant Glu(14)Gly is approximately two times higher than wildtype, and that this increase is primarily due to the increased expression and/or stability of the mutant ACAT2 protein.

Conclusions: These results suggest that the genetic variation at Glu(14)Gly is functionally important and may contribute to ACAT2 protein expression and stability.