fig1

Figure 1. CD63 regulates the cellular cholesterol balance and export through exosomes. The expression and function of CD63, which seem to be partly regulated by mitochondrial fatty acid metabolism, promote cholesterol transfer from the membrane of the MVBs to CD63 cholesterol-binding pocket. After budding and formation of ILV within the MVB, CD63 enriches ILV in cholesterol, constituting lipid raft-like domains. The subsequent secreted CD63+ exosomes enriched in cholesterol can, therefore, deliver their lipid content to receipt cells and favor the exchanges of cholesterol with cells/organs of interest(s) through exosomes. In pathological contexts linked to lipid disorders such as fatty acid metabolism dysregulation or dyslipidemia, CD63 expression and/or function is altered, the cholesterol is rerouted to other organelles, and CD63-deficient exosomes released are poorly concentrated in cholesterol. ILV: Intraluminal vesicles; MVBs: multivesicular bodies.