LIPOPROTEINS, LIPID DROPLETS, LYSOSOMES, AND ADRENOCORTICAL STEROID-HORMONE SYNTHESIS - MORPHOLOGICAL-STUDIES

Recent studies concerning cellular cholesterol homeostasis suggest tha t there is a relationship between the serum lipoproteins (low density and high density lipoproteins: LDL and HDL), the intracellular storage of cholesterol (Lipid droplets), lysosomes, and the steroidogenic act ivity of adrenocortical cells. This review surveys the current knowled ge on cholesterol import from LDL/HDL by adrenocortical cells, its reg ulation, and the participation of lipid droplets and lysosomes in this process. The possible role of adrenocortical cell microvilli in the u ptake of LDL/HDL is discussed. Under certain physiological, experiment al, and pathological circumstances lysosomes accumulate unesterified a nd/or esterified cholesterol in the form of lipid-lysosome complexes. As suggested bg the data presented in this review. lipid-lysosome comp lexes appear to be involved in cholesterol homeostasis, via altering l ipid compartmentalization. Since previous reports do not clearly demon strate a positive correlation between the volume of lipid- and lysosom e-compartments and the rate of steroid hormone synthesis [for review, see Nussdorfer (1986) Int. Rev. Cytol., 98:1-405], the objective of th is review is to provide a better understanding of the interactions of plasma lipoproteins, lipid droplets, lysosomes, and steroidogenesis. ( C) 1997 Wiley-Liss, Inc.