title: Biochemical mechanism of pathogenesis of human gonadotropin-releasing hormone receptor mutants Thr104Ile and Tyr108Cys associated with familial hypogonadotropic hypogonadism.
abstract: The pathogenic mechanisms whereby the Thr104Ile and Tyr108Cys mutations in the gonadotropin-releasing hormone receptor (GnRHR) gene cause hypogonadotropic hypogonadism in humans are unknown. Transient expression of Thr104Ile and Tyr108Cys mutants in COS-7 cells revealed that both GnRHR mutants neither bind nor respond to agonist. Removal of Lys191 rescued function of both mutants, while addition of a carboxyl-terminal targeting sequence only rescued function of the Thr104Ile mutant. Exposure to the pharmacoperone In3 rescued almost completely Thr104Ile mutant function to wild-type levels, whereas rescue was partial for the Tyr108Cys GnRHR. Additional mutations that block formation of bridges involving Cys108 showed that a Cys108-Cys200 disulfide bridge is the predominant moiety formed in the Tyr108Cys mutant. Thr104Ile and Tyr108Cys GnRHRs are misfolded structures whose function is rescuable by genetic and/or pharmacological strategies. The Tyr108Cys mutant forms an aberrant disulfide bridge that prevents formation of the required Cys14-Cys200 bridge essential for GnRHR plasma membrane expression.
authors.affiliation: Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia "Luis Castelazo Ayala", Instituto Mexicano del Seguro Social, México D.F., Mexico. mayanune@yahoo.com
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Maya-Núñez
authors.forename: Jo Ann
authors.initials: JA
authors.lastname: Janovick
authors.forename: Arturo
authors.initials: A
authors.lastname: Aguilar-Rojas
authors.forename: Eduardo
authors.initials: E
authors.lastname: Jardón-Valadez
authors.forename: Alfredo
authors.initials: A
authors.lastname: Leaños-Miranda
authors.forename: Teresa
authors.initials: T
authors.lastname: Zariñan
authors.forename: Alfredo
authors.initials: A
authors.lastname: Ulloa-Aguirre
authors.forename: P Michael
authors.initials: PM
authors.lastname: Conn
mesh_terms: D001667:Binding, Competitive; D002064:Buserelin / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007006:Hypogonadism / Q000235:genetics*; D020128:Inhibitory Concentration 50; D007295:Inositol Phosphates / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D020125:Mutation, Missense; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011966:Receptors, LHRH / Q000819:agonists / Q000235:genetics* / Q000378:metabolism
chemical_list: D007295:Inositol Phosphates; D011966:Receptors, LHRH; D002064:Buserelin