Cholesterol synthesis

The cholesterol synthesis pathway is a key intracellular signaling pathway that regulates cellular lipid metabolism. As such, it is directly involved in cell membrane formation, steroid hormone synthesis, bile acid production, and cellular homeostasis. Starting from acetyl-CoA as the initial substrate, the mevalonate pathway undergoes a series of reactions to produce squalene, which is then converted into cholesterol through a series of reactions including cyclization and oxidation. This pathway contains several key regulatory nodes, such as HMG-CoA reductase, squalene synthase, and lanosterol synthase, which can influence the rate and yield of cholesterol synthesis. Many known factors can enhance the cholesterol synthesis pathway, including insulin, thyroid hormones, low-density lipoprotein receptor-related protein, and SREBP transcription factors. Both insulin and thyroid hormones promote cholesterol synthesis by activating related signaling pathways. This pathway can be antagonized by various factors, including statins, cholesterol itself, PTEN, and AMPK.