HDL biology
ApoE boosts CETP-mediated lipid exchange by raising the affinity of VLDL for CETP (J Lipid Res 1993)
Original title: Apolipoprotein E enhances lipid exchange between lipoproteins mediated by cholesteryl ester transfer protein
Using lipoproteins from an apoE-deficient subject as a model system, this study tested the direct effect of apoE on CETP activity. Incorporating apoE into VLDL enhanced cholesteryl ester transfer from discoidal bilayer particles to VLDL, but only when CETP was present. After incubating CETP with VLDL, CETP activity and immunoreactivity co-eluted with apoE-containing VLDL on gel filtration but showed little co-elution with apoE-free VLDL, indicating apoE-containing VLDL has higher affinity for CETP. Supplementing apoE-deficient serum with apoE enhanced CETP-mediated changes in cholesteryl ester and triglyceride content of the HDL fraction, an effect completely blocked by a CETP-inhibiting monoclonal antibody. The authors conclude that apoE enhances CETP-mediated cholesteryl ester and triglyceride transfer between VLDL and HDL, likely by increasing the affinity of CETP for VLDL.
Original abstract
The direct effect of apolipoprotein (apo) E on cholesteryl ester transfer protein (CETP) activity was studied using lipoproteins from a subject with apoE deficiency (Atherosclerosis. 1991. 88: 15-20) as a model system. The transfer of cholesteryl ester (CE) from discoidal bilayer particles (DBP) to very low density lipoprotein (VLDL) was enhanced by incorporation of apoE into VLDL. This enhancement was induced only in the presence of CETP activity. Moreover, after incubation of CETP with VLDL, CETP activity and immunoreactivity were coeluted with apoE-incorporated VLDL (E-VLDL) on a gel filtration column (Sephadex G-150), but there was little CETP activity and immunoreactivity with apoE-free VLDL (C-VLDL), suggesting that E-VLDL had higher affinity for CETP compared to C-VLDL. The supplementation of the apoE-deficient serum with apoE enhanced the CETP-mediated changes of amount of CE and triglyceride (TG) in the high density lipoprotein (HDL) fraction, which were completely inhibited by the addition of the monoclonal antibody against CETP that blocks CETP activity. Our results suggest that 1) apoE enhances the cholesteryl ester and triglyceride transfer between VLDL and HDL via cholesteryl ester transfer protein, and 2) this effect of apoE may be mediated by enhancing the affinity of CETP for VLDL.
Summary written by cetpinhibition.org from the published abstract; figures as published. Page updated 19 August 2026. Methods.