TARGETED DISRUPTION OF THE MOUSE LECITHIN-CHOLESTEROL ACYLTRANSFERASE(LCAT) GENE - GENERATION OF A NEW ANIMAL-MODEL FOR HUMAN LCAT DEFICIENCY

We have established a mouse model for human LCAT deficiency by perform ing targeted disruption of the LCAT gene in mouse embryonic stem cells , Homozygous LCAT-deficient mice were healthy at birth and fertile, Co mpared with age-matched wild-type littermates, the LCAT activity in he terozygous and homozygous knockout mice was reduced by 30 and 99%, res pectively, LCAT deficiency resulted in significant reductions in the p lasma concentrations of total cholesterol, HDL cholesterol, and apoA-I in both LCAT -/- mice (25, 7, and 12%; p < 0.001 of normal) and LCAT +/- mice (65 and 59%;p < 0.001 and 81%; not significant, p = 0.17 of n ormal), In addition, plasma triglycerides were significantly higher (2 12% of normal; p < 0.01) in male homozygous knockout mice compared wit h wild-type animals but remained normal in female knockout LCAT mice, Analyses of plasma lipoproteins by fast protein liquid chromatography and two-dimensional gel electrophoresis demonstrated the presence of h eterogenous prep-migrating HDL, as well as triglyceride-enriched very low density lipoprotein, After 3 weeks on a high-fat high-cholesterol diet, LCAT -/- mice had significantly lower plasma concentrations of t otal cholesterol, reflecting reduced levels of both proatherogenic apo B-containing lipoproteins as well as HDL, compared with controls, Thus , we demonstrate for the first time that the absence of LCAT attenuate s the rise of apoB-containing lipoproteins in response to dietary chol esterol, No evidence of corneal opacities or renal insufficiency was d etected in 4-month-old homozygous knockout mice, The availability of a homozygous animal model for human LCAT deficiency states will permit further evaluation of the role that LCAT plays in atherosclerosis as w ell as the feasibility of performing gene transfer in human LCAT defic iency states.