ApoA-II modulates the association of HDL with class B scavenger receptors SR-BI and CD36

• Main Authors: Maria C. de Beer, Lawrence W. Castellani, Lei Cai, Arnold J. Stromberg, Frederick C. de Beer, Deneys R. van der Westhuyzen
• Format: Article
• Language: English
• Published: Elsevier 2004-04-01
• Series: Journal of Lipid Research
• Subjects: lipoprotein metabolism; selective lipid uptake; atherosclerosis; apolipoprotein A-II; high density lipoprotein
• Online Access: http://www.sciencedirect.com/science/article/pii/S0022227520318551

The class B scavenger receptors SR-BI and CD36 exhibit a broad ligand binding specificity. SR-BI is well characterized as a HDL receptor that mediates selective cholesteryl ester uptake from HDL. CD36, a receptor for oxidized LDL, also binds HDL and mediates selective cholesteryl ester uptake, although much less efficiently than SR-BI. Apolipoprotein A-II (apoA-II), the second most abundant HDL protein, is considered to be proatherogenic, but the underlying mechanisms are unclear. We previously showed that apoA-II modulates SR-BI-dependent binding and selective uptake of cholesteryl ester from reconstituted HDL. To investigate the effect of apoA-II in naturally occurring HDL on these processes, we compared HDL without apoA-II (from apoA-II null mice) with HDLs containing differing amounts of apoA-II (from C57BL/6 mice and transgenic mice expressing a mouse apoA-II transgene). The level of apoA-II in HDL was inversely correlated with HDL binding and selective cholesteryl ester uptake by both scavenger receptors, particularly CD36. Interestingly, for HDL lacking apoA-II, the efficiency with which CD36 mediated selective uptake reached a level similar to that of SR-BI.These results demonstrate that apoA-II exerts a marked effect on HDL binding and selective lipid uptake by the class B scavenger receptors and establishes a potentially important relationship between apoA-II and CD36.