Low-density lipoprotein receptor regulatory machinery

The Low-density lipoprotein receptor (LDLR) regulatory machinery is a complex network of proteins and pathways responsible for maintaining cholesterol homeostasis by controlling the abundance and activity of LDLR on the cell surface, primarily in the liver [1, 3]. This machinery includes transcriptional regulators like SREBP-2, which increases LDLR expression when cellular cholesterol is low, and post-translational regulators like PCSK9 and IDOL, which promote the degradation of the receptor [1, 5]. By modulating these components, the body can fine-tune the clearance of LDL-cholesterol from the bloodstream [7]. Dysregulation of this machinery, such as gain-of-function mutations in PCSK9 or loss-of-function mutations in LDLR, leads to hypercholesterolemia and increased risk of cardiovascular disease [1, 7]. Therapeutic strategies targeting this machinery, including statins and PCSK9 inhibitors, are cornerstones of modern lipid-lowering therapy, aimed at increasing LDLR density to reduce circulating LDL levels [3, 6].

Other names

Low-density lipoprotein receptor regulatory pathwayCholesterol homeostatic machineryPCSK9-LDLR axisSREBP-SCAP-LDLR pathway

Drugs targeting this machinery work by either increasing the transcription of the LDLR gene or by preventing the degradation of the LDLR protein. Statins and bempedoic acid inhibit cholesterol synthesis, which triggers the SREBP-2 pathway to upregulate LDLR expression [1, 3]. PCSK9 inhibitors, such as monoclonal antibodies (evolocumab, alirocumab) or siRNA (inclisiran), block the PCSK9-mediated degradation of LDLR, thereby increasing the number of receptors available on the hepatocyte surface to clear LDL-cholesterol from the plasma [3, 7].