Desmocollin 1 is abundantly expressed in atherosclerosis and impairs high-density lipoprotein biogenesis

Aims The biogenesis of high-density lipoprotein (HDL) particles by cholesterol-laden foam cells in atherosclerotic lesions is crucial for the removal of excess cholesterol from the lesions. Impairment in the HDL biogenic process contributes to the progression of atherosclerosis. The aim of this study is to identify novel cellular factors regulating HDL biogenesis. Methods and results HDL biogenesis is a process of apolipoprotein (apo)-mediated solubilization of specific plasma membrane (PM) microdomains generated in cholesterol-accumulated cells. We established a new method to isolate PM microdomains interacting with the major HDL protein constituent, apoA-I. Lipidomic and proteomic analyses of an isolated PM microdomain revealed that apoA-I binds to cholesterol-rich and desmocollin 1 (DSC1)-containing microdomains. In this novel apoA-I binding microdomain, DSC1 binds and prevents apoA-I from interacting with another PM microdomain created by adenosine triphosphate-binding cassette transporter A1 (ABCA1) for the formation of HDL. Inhibition of apoA-I-DSC1 binding by silencing DSC1 expression or using DSC1 blocking antibodies increases apoA-I accessibility to ABCA1-created microdomains and thus enhances HDL biogenesis. Importantly, DSC1 is abundantly expressed in macrophages and human atherosclerotic lesions, suggesting that DSC1 may contribute to cholesterol accumulation in atherosclerotic lesions by sequestering apoA-I and impairing HDL biogenesis. Conclusions The binding of apoA-I to two functionally opposing PM microdomains, ABCA1 and DSC1 domains, suggests that HDL biogenesis and PM cholesterol levels may be regulated by the relative abundance of the two domains and that novel HDL biogenic therapies may be developed by targeting DSC1.