PCSK9
Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease encoded by the PCSK9 gene on human chromosome 1p32.3, which regulates low-density lipoprotein (LDL) cholesterol homeostasis by binding to LDL receptors (LDLR) on the surface of hepatocytes and promoting their internalization and lysosomal degradation.[1][2][3]
Originally identified in 2003 through genetic studies linking missense mutations to autosomal dominant hypercholesterolemia, PCSK9's gain-of-function variants reduce LDLR recycling, elevating circulating LDL cholesterol and increasing atherosclerotic cardiovascular disease risk, whereas loss-of-function mutations enhance LDL clearance and correlate with reduced coronary heart disease incidence.[4][5][6]
The protein's therapeutic targeting via monoclonal antibodies such as evolocumab and alirocumab inhibits this degradative pathway, achieving LDL cholesterol reductions of 50-60% in clinical trials and demonstrating significant decreases in major adverse cardiovascular events among statin-intolerant or high-risk patients refractory to conventional lipid-lowering therapies.[7][8][9]
Beyond lipid metabolism, emerging evidence suggests PCSK9 influences glucose homeostasis, inflammation, and vascular function, though its primary clinical significance remains in cardiovascular risk management.[10][11]