Proprotein convertase subtilisin/kexin type 9 messenger RNA (PCSK9 mRNA) (PCSK9 mRNA)

Proprotein convertase subtilisin/kexin type 9 (PCSK9) messenger RNA is the transcript responsible for the production of the PCSK9 protein, a key regulator of cholesterol metabolism (UniProt Q8NBP7). The PCSK9 protein facilitates the degradation of low-density lipoprotein receptors (LDLR) in the liver, thereby reducing the clearance of LDL cholesterol from the bloodstream (NIH StatPearls). By targeting the mRNA transcript rather than the protein itself, therapeutic agents like small interfering RNAs (siRNAs), such as Inclisiran, utilize the RNA-induced silencing complex (RISC) to cleave the mRNA and prevent protein translation (FDA Leqvio Label). This reduction in PCSK9 levels leads to an increase in LDLR density on hepatocyte surfaces, significantly lowering plasma LDL cholesterol levels and reducing cardiovascular risk. Current clinical applications focus on patients with atherosclerotic cardiovascular disease or primary hypercholesterolemia who require additional lipid-lowering therapy (EMA Leqvio Assessment Report). This approach offers a long duration of action, often requiring only twice-yearly dosing, which improves patient adherence compared to daily or bi-weekly treatments.

Drugs targeting this mRNA, such as Inclisiran, utilize the RNA interference (RNAi) pathway where the antisense strand of the siRNA guides the RNA-induced silencing complex (RISC) to the PCSK9 mRNA, leading to its catalytic cleavage and degradation.