Functional Consequences of a Novel Variant of PCSK1

Abstract

BackgroundCommon single nucleotide polymorphisms (SNPs) in proprotein convertase subtilisin/kexin type 1 with modest effects on PC1/3 in vitro have been associated with obesity in five genome-wide association studies and with diabetes in one genome-wide association study. We here present a novel SNP and compare its biosynthesis, secretion and catalytic activity to wild-type enzyme and to SNPs that have been linked to obesity.Methodology/Principal FindingsA novel PC1/3 variant introducing an Arg to Gln amino acid substitution at residue 80 (within the secondary cleavage site of the prodomain) (rs1799904) was studied. This novel variant was selected for analysis from the 1000 Genomes sequencing project based on its predicted deleterious effect on enzyme function and its comparatively more frequent allele frequency. The actual existence of the R80Q (rs1799904) variant was verified by Sanger sequencing. The effects of this novel variant on the biosynthesis, secretion, and catalytic activity were determined; the previously-described obesity risk SNPs N221D (rs6232), Q665E/S690T (rs6234/rs6235), and the Q665E and S690T SNPs (analyzed separately) were included for comparative purposes. The novel R80Q (rs1799904) variant described in this study resulted in significantly detrimental effects on both the maturation and in vitro catalytic activity of PC1/3.Conclusion/SignificanceOur findings that this novel R80Q (rs1799904) variant both exhibits adverse effects on PC1/3 activity and is prevalent in the population suggests that further biochemical and genetic analysis to assess its contribution to the risk of metabolic disease within the general population is warranted.

Revisiting PC1/3 Mutants: Dominant-Negative Effect of Endoplasmic Reticulum-Retained Mutants

“…Visualization of immunoreactive proteins was accomplished using the Clarity enhanced chemiluminescent Western blotting substrate (Bio-Rad), and images were obtained with a ChemiDoc MP imaging system (Bio-Rad). Of note, this system yielded much more reliable protein quantitation than that previously obtained data using film (6,16).…”

“…14) were performed using a PC1/3 expression vector containing an additional mutation, S357G (4,6,7,12,15,16). The cDNA used as a template for the generation of this construct was originally cloned from a human carcinoid lung tumor (17).…”

Association between rs155971 in the PCSK1 gene and the lipid profile of obese Thai children: a family-based study

“…PC1/3 is a protein that converts a variety of prohormones and neuropeptide precursors, such as proinsulin and POMC, to their functional forms (Seidah et al, 1991;Pickett et al, 2013). One of the functions of PC1/3 is to control energy balance (Choquet and Meyre, 2010;Chung, 2012).…”

A Novel Familial Mutation in the PCSK1 Gene That Alters the Oxyanion Hole Residue of Proprotein Convertase 1/3 and Impairs Its Enzymatic Activity

“…The enzyme encoded by PCSK1 , the neuroendocrine convertase 1 precursor, cleaves itself into the active form, neuroendocrine convertase 1 (also called prohormone convertase 1, proprotein convertase 1, and PC1), which is responsible for processing multiple peptide hormones within the enteroendocrine cell. Other rare heterozygous mutations in PCSK1 have been observed in the general population, which likely would be harmful in an individual with two damaged copies of the gene [12] . PC1/3 deficiency involves a significant risk of mortality and failure to thrive secondary to severe generalized malabsorptive diarrhea in early childhood.…”