Open Access
Article
Cholesterol uptake in adrenal and gonadal tissues: the SR-BI and 'selective' pathway connection
Salman Azhar1,Susan Leers-Sucheta1,Eve Reaven1
1
Geriatric Research, Education and Clinical Center, VA Palo Alto Heath Care System, Palo Alto, California 94304, USA. salman.azhar@med.va.gov
DOI: 10.2741/1165 Volume 8 Issue 6, pp.998-1029
Published: 01 September 2003
(This article belongs to the Special Issue Lipid binding, modifying and transferring proteins)
Abstract

A constant supply of cholesterol is needed as a substrate for steroid hormone synthesis in steroidogenic tissues. Although there are three potential sources, which could contribute to the 'cholesterol pool', needed for steroidogenesis (i.e., de novo synthesis, hydrolysis of stored cholesteryl esters and exogenous lipoproteins), current evidence suggests that plasma lipoproteins are the major source of cholesterol for steroid production in adrenal gland, ovary and, under certain conditions, testicular Leydig cells. In many species, steroid producing cells and tissues obtain this lipoprotein-cholesterol by a unique pathway in which circulating lipoproteins bind to the surface of the steroidogenic cells and contribute their cholesteryl esters to the cells by a 'selective' process. This is a process in which cholesterol is selectively absorbed while the lipoprotein remains at the cell surface. The discovery of a specific receptor for this process (scavenger receptor class B, type I, known as SR-BI) has revolutionized our knowledge about the selective uptake pathway. The present review summarizes the functional importance of the selective pathway as a bulk cholesterol delivery system for steroidogenesis, and attempts to detail the expression, regulation and characteristics of SR-BI as it is deployed in steroidogenic systems as a means of achieving cholesterol balance.

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Salman Azhar, Susan Leers-Sucheta, Eve Reaven. Cholesterol uptake in adrenal and gonadal tissues: the SR-BI and 'selective' pathway connection. Frontiers in Bioscience-Landmark. 2003. 8(6); 998-1029.