Obesity and impaired prohormone processing associated with mutations in the human prohormone convertase 1 gene

• Published in: Nature genetics Vol. 16; no. 3; pp. 303 - 306
• Main Authors: Creemers, John W.M, Jackson, Robert S, Montague, Carl T, Ohagi, Shinya, Raffin-Sanson, Marie-Laure, Hutton, John C, O'Rahilly, Stephen, Sanders, Louise
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 01.07.1997
• Subjects: Amino Acid Sequence; Animals; Aspartic Acid Endopeptidases - genetics; Aspartic Acid Endopeptidases - metabolism; Biological and medical sciences; Carboxypeptidase H; Carboxypeptidases - metabolism; CHO Cells; Cricetinae; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Endoplasmic Reticulum - enzymology; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Female; Fluorescent Antibody Technique; Heterozygote; Humans; Medical sciences; Mice; Mice, Inbred Strains; Microscopy, Fluorescence; Molecular Sequence Data; Mutation; Obesity - enzymology; Obesity - genetics; Polymerase Chain Reaction; Polymorphism, Single-Stranded Conformational; Proprotein Convertase 1; Proprotein Convertases; Protein Precursors - metabolism; Protein Processing, Post-Translational; RNA Splicing; RNA, Messenger - genetics; Transfection; Endocrinopathy; Human; Obesity; Molecular processing; Serine endopeptidases; Enzyme; Nutrition disorder; Metabolic diseases; Prohormone; Peptidases; Prohormone convertase I; Gene; Hydrolases; Genetics; Mutation
• ISSN: 1061-4036; 1546-1718
• DOI: 10.1038/ng0797-303

Human obesity has an inherited component, but in contrast to rodent obesity, precise genetic defects have yet to be defined. A mutation of carboxypeptidase E (CPE), an enzyme active in the processing and sorting of prohormones, causes obesity in the fat/fat mouse. We have previously described a women with extreme childhood obesity (Fig. 1), abnormal glucose homeostasis, hypogonadotrophic hypogonadism, hypocortisolism and elevated plasma proinsulin and pro-opiomelanocortin (POMC) concentrations but a very low insulin level, suggestive of a defective prohormone processing by the endopeptidase, prohormone convertase 1 (PC1; ref. 4). We now report this proband to be a compound heterozygote for mutations in PC1. Gly-->Arg483 prevents processing of proPC1 and leads to its retention in the endoplasmic reticulum (ER). A-->C+4 of the intro-5 donor splice site causes skipping of exon 5 leading to loss of 26 residues, a frameshift and creation of a premature stop codon within the catalytic domain. PC1 acts proximally to CPE in the pathway of post-translational processing of prohormones and neuropeptides. In view of the similarity between the proband and the fat/fat mouse phenotype, we infer that molecular defects in prohormone conversion may represent a generic mechanism for obesity, common to humans and rodents.