Cholesterol

General description
Cholesterol, a major sterol is the precursor for steroid hormones, bile acid and vitamin in mammals[1] and coordinates endocytosis.[2] It complexes with protein to form lipoproteins for transport in blood. It exists either as high-density lipoprotein (HDL) or low-density lipoprotein (LDL). HDL also called good cholesterol has less lipid content. LDL or bad cholesterol has high lipid content. Statin inhibition of HMG-CoA reductase enzyme in the cholesterol biosynthesis pathway controls elevated cholesterol levels in atherosclerosis and hypercholesterolemia.[2] Low levels of cholesterol results in hypothyroidism, familial hypobetalipoproteinemia and liver disease.[1] Imbalance of cholesterol homeostasis and intracellular cholesterol levels play a key role in cancer development.[3] High cholesterol levels favor breast cancer progression.[4] Application
Cholesterol has been used:
as a medium supplement in chorionic villous tissue culture form placenta[5] as a component of hormone pellet for implantation in mice ovary[6] for inducing expression of immunity-related GTPase M (IRGM) in human monocytic cell line, THP-1[7]

Biochem/physiol Actions
Major component of all biological membranes; ~25% of total brain lipid is cholesterol.