BACKGROUND: Proprotein convertase 1/3 (PC1/3) is one of the endoproteases initiating the proteolytic activation of prohormones and proneuropeptides in the secretory pathway. It is produced as a zymogen that is subsequently modified by activity-determining cleavages at the amino and the carboxyl termini. In human, it is encoded by the PCSK1 locus on chromosome 5. Spontaneous inactivating mutations in its gene have been linked to obesity. Minor alleles of the common non-synonymous single-nucleotide polymorphisms (SNPs) rs6232 (T>C, N221D), rs6234 (G>C, Q665E) and rs6235 (C>G, S690T) have been associated with increased risk of obesity. We have shown that the variations associated with these SNPs are linked on minor PCSK1 alleles. GOAL: In this study, we examined the impact of amino acid substitutions specified by the minor PCSK1 alleles on PC1/3 biosynthesis and prohormone processing activity in cultured cells. METHODS: The common and variant isoforms of PC1/3 were expressed in transfected rat pituitary GH4C1 cells with or without proopiomelanocortin (POMC) as a substrate. Secreted PC1/3- or POMC-related proteins and peptides were analyzed by immunoblotting and immunoprecipitation. RESULTS: When expressed in GH4C1 cells, the triple-variant PC1/3 underwent significantly more proteolytic processing at the amino and carboxyl termini than the common and double-variant isoforms. However, there was no detectable difference among these isoforms in their ability to process POMC in the transfected cells. CONCLUSIONS: Since truncation of PC1/3 in its C-terminal region reportedly renders the enzyme unstable, we speculate that the accentuated processing of the triple variant in this region may, in vivo, create a subtle deficit of PC1/3 enzymatic activity in endocrine and neuroendocrine cells, causing impaired processing of prohormones and proneuropeptides to their bioactive forms.
BACKGROUND:Proprotein convertase 1/3 (PC1/3) is one of the endoproteases initiating the proteolytic activation of prohormones and proneuropeptides in the secretory pathway. It is produced as a zymogen that is subsequently modified by activity-determining cleavages at the amino and the carboxyl termini. In human, it is encoded by the PCSK1 locus on chromosome 5. Spontaneous inactivating mutations in its gene have been linked to obesity. Minor alleles of the common non-synonymous single-nucleotide polymorphisms (SNPs) rs6232 (T>C, N221D), rs6234 (G>C, Q665E) and rs6235 (C>G, S690T) have been associated with increased risk of obesity. We have shown that the variations associated with these SNPs are linked on minor PCSK1 alleles. GOAL: In this study, we examined the impact of amino acid substitutions specified by the minor PCSK1 alleles on PC1/3 biosynthesis and prohormone processing activity in cultured cells. METHODS: The common and variant isoforms of PC1/3 were expressed in transfected rat pituitary GH4C1 cells with or without proopiomelanocortin (POMC) as a substrate. Secreted PC1/3- or POMC-related proteins and peptides were analyzed by immunoblotting and immunoprecipitation. RESULTS: When expressed in GH4C1 cells, the triple-variant PC1/3 underwent significantly more proteolytic processing at the amino and carboxyl termini than the common and double-variant isoforms. However, there was no detectable difference among these isoforms in their ability to process POMC in the transfected cells. CONCLUSIONS: Since truncation of PC1/3 in its C-terminal region reportedly renders the enzyme unstable, we speculate that the accentuated processing of the triple variant in this region may, in vivo, create a subtle deficit of PC1/3 enzymatic activity in endocrine and neuroendocrine cells, causing impaired processing of prohormones and proneuropeptides to their bioactive forms.
Authors: Francine Sirois; Nadine Kaefer; Krista A Currie; Michel Chrétien; Kabwe K Nkongolo; Majambu Mbikay Journal: J Community Genet Date: 2012-02-04
Authors: Yogikala Prabhu; Elias H Blanco; Ming Liu; Juan R Peinado; Matthew C Wheeler; Nicholas Gekakis; Peter Arvan; Iris Lindberg Journal: Endocrinology Date: 2014-05-14 Impact factor: 4.736
Authors: Kevin T Nead; Aihua Li; Mackenzie R Wehner; Binod Neupane; Stefan Gustafsson; Adam Butterworth; James C Engert; A Darlene Davis; Robert A Hegele; Ruby Miller; Marcel den Hoed; Kay-Tee Khaw; Tuomas O Kilpeläinen; Nick Wareham; Todd L Edwards; Göran Hallmans; Tibor V Varga; Sharon L R Kardia; Jennifer A Smith; Wei Zhao; Jessica D Faul; David Weir; Jie Mi; Bo Xi; Samuel Canizales Quinteros; Cyrus Cooper; Avan Aihie Sayer; Karen Jameson; Anders Grøntved; Myriam Fornage; Stephen Sidney; Craig L Hanis; Heather M Highland; Hans-Ulrich Häring; Martin Heni; Jessica Lasky-Su; Scott T Weiss; Glenn S Gerhard; Christopher Still; Melkaey M Melka; Zdenka Pausova; Tomáš Paus; Struan F A Grant; Hakon Hakonarson; R Arlen Price; Kai Wang; Andre Scherag; Johannes Hebebrand; Anke Hinney; Paul W Franks; Timothy M Frayling; Mark I McCarthy; Joel N Hirschhorn; Ruth J Loos; Erik Ingelsson; Hertzel C Gerstein; Salim Yusuf; Joseph Beyene; Sonia S Anand; David Meyre Journal: Hum Mol Genet Date: 2015-03-17 Impact factor: 6.150
Authors: Lindsay A Pickett; Michael Yourshaw; Valeria Albornoz; Zijun Chen; R Sergio Solorzano-Vargas; Stanley F Nelson; Martín G Martín; Iris Lindberg Journal: PLoS One Date: 2013-01-28 Impact factor: 3.240