Lipoproteins, lipid droplets, lysosomes, and adrenocortical steroid hormone synthesis: morphological studies.
Recent studies concerning cellular cholesterol homeostasis suggest that 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 activity of adrenocortical cells. This review surveys the current knowledge on cholesterol import from LDL/HDL by adrenocortical cells, its regulation, and the participation of lipid droplets and lysosomes in this process. The possible role of adrenocortical cell microvilli in the uptake of LDL/HDL is discussed. Under certain physiological, experimental, and pathological circumstances lysosomes accumulate unesterified and/or esterified cholesterol in the form of lipid-lysosome complexes. As suggested by the data presented in this review, lipid-lysosome complexes appear to be involved in cholesterol homeostasis, via altering lipid compartmentalization. Since previous reports do not clearly demonstrate a positive correlation between the volume of lipid- and lysosome-compartments and the rate of steroid hormone synthesis [for review, see Nussdorfer (1986) Int. Rev. Cytol., 98:1-405], the objective of this review is to provide a better understanding of the interactions of plasma lipoproteins, lipid droplets, lysosomes, and steroidogenesis.
Tóth
I E
IE
Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.
Szabö
D
D
Bruckner
G G
GG
D000305:Adrenal Cortex Hormones / Q000096:biosynthesis*; D000818:Animals; D002451:Cell Compartmentation; D002784:Cholesterol / Q000378:metabolism*; D006706:Homeostasis; D006801:Humans; D008074:Lipoproteins / Q000097:blood*; D008081:Liposomes; D008247:Lysosomes / Q000648:ultrastructure*; D013256:Steroids / Q000096:biosynthesis*
D000305:Adrenal Cortex Hormones; D008074:Lipoproteins; D008081:Liposomes; D013256:Steroids; D002784:Cholesterol