Development of Peptide Inhibitors Disrupting PCSK9-LDLR Protein-Protein Interactions

摘要

Cardiovascular disease (CVD) is the leading cause of global mortality. Hypercholesterolemia, characterized by increased plasma low-density lipoprotein (LDL) cholesterol, is a major determinant of CVD risk. Proprotein convertase subtilisin/kexin 9 (PCSK9) plays a critical role in cholesterol homeostasis by regulating LDL receptor (LDLR) protein levels. PCSK9 binds to the EGF-A domain of the LDLR and promotes its internalization and degradation in endosomal/lysosomal compartments [1]. Inhibition of PCSK9 action on LDLR has emerged as a novel therapeutic target for hypercholesterolemia and the prevention of CVD [1]. The present study attempts to evaluate if small peptides can be used to interfere with the protein-protein interactions of PCSK9 with EGF-A domain. Initially we used a strategy with positional scanning of synthetic peptide combinatorial libraries (PS-SPCL) from a L-hexa and L-decapeptide library to analyze the potential of small peptides to inhibit PCSK9 (Figure 1) in a cell-based assay measuring fluorescent LDL incorporation. Our results from the SP-SPCL approach showed the potential of small peptides to prevent reduction in LDL uptake from PCSK9 effect. Also, based on the 40 aa sequence of EGF-A domain and molecular modeling from the co-crystal of PCSK9:EGF-A [2], we synthesized a cyclic peptide of 13 aa that prevents PCSK9 effect on LDL uptake.