Cholesterol: Synthesis, Metabolism, Regulation
The rate limiting step in cholesterol synthesis ..
As eukaryotic genes mediating lipid metabolism, the expression of LDLR is also under intricate regulation at both the transcriptional and posttranscriptional levels, which are mediated through precise signalling pathways (Fig.). Cholesterol and its derivatives, as well as nonsterol factors, including inflammation mediator, growth factors, certain hormones, glucose and its metabolites are able to regulate LDLR expression[, ].
the rate-determining step of cholesterol synthesis
Cholesterol is an insoluble lipid molecule that plays a critical role in the structure and function of membrane bilayers. Membrane cholesterol contents that are either too high or too low are detrimental to cell function. When present in excess amounts in cells, cholesterol becomes toxic. Certainly, cholesterol-induced cytotoxicity represents a key initiating event leading to the development of atherosclerotic cardiovascular disease. Cholesterol is also used as a substrate for steroid hormone biosynthesis. Virtually all cells are capable of synthesizing their full complement of cholesterol, despite the capacity of the gastrointestinal tract to absorb large quantities. However, only hepatocytes within the liver are capable of degrading cholesterol and eliminating it in large quantities.