On the role of oxysterols in regulation of cholesterol homeostasis by nuclear receptors

摘要

Although oxysterol may be generated from numerous parent compounds they are - for the purposes of this review - defined as derivatives of cholesterol that contain at least one oxygen function in addition to the 3p-hydroxyl group. Although cholesterol may be oxygenated at virtually every position, only a select few of these oxysterols are found at significant levels in biological locations (see Table 1 for a summary of the consensus plasma concentrations of different oxysterols). It should be emphasized that in virtually every biological location these compounds are present in a matrix containing a vast excess of cholesterol (generally 5000-10000 fold excess). It is also noteworthy that the major oxysterols present in the human circulation are produced by enzymatic mechanisms, and have defined roles as intermediates (or end-products) in cell, organ or whole-body cholesterol elimination pathways.