Intracellular retention is a common characteristic of childhood obesity-associated MC4R mutations

• Published in: Human molecular genetics 2003-01, Vol.12 (2), p.145-153
• Main Authors: Lubrano-Berthelier, Cecile, Durand, Emmanuelle, Dubern, Beatrice, Shapiro, Astrid, Dazin, Paul, Weill, Jacques, Ferron, Camille, Froguel, Philippe, Vaisse, Christian
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Biological and medical sciences; Cell Line; Cell Membrane - metabolism; Child; Child, Preschool; Cohort Studies; Female; Gene Expression; Genetic Variation; Genetics; Human genetics; Humans; Life Sciences; Male; Medical sciences; Metabolic diseases; Molecular Sequence Data; Mutation; Obesity; Obesity - genetics; Pedigree; Prevalence; Receptor, Melanocortin, Type 4; Receptors, Corticotropin - genetics; Transfection
• ISSN: 0964-6906; 1460-2083; 1460-2083
• DOI: 10.1093/hmg/ddg016

Heterozygous mutations in the coding region of the serpentine Melanocortin 4 receptor are the most common genetic cause of human obesity described to date. There are still conflicting data regarding the overall prevalence of such mutations in obesity and limited information is available on the functional defects caused by most obesity-associated MC4R mutations. We report here the screening for mutations in the coding region of the MC4R of a new cohort of 172 patients presenting with severe childhood obesity and a family history of obesity. Three heterozygous MC4R mutations (Ser127Leu, Ala244Glu and Pro299His) were found in three patients of this cohort (1.74%), confirming that such mutations are implicated in a significant number of childhood obesity cases. A functional analysis of these mutant receptors, in addition to 11 other childhood obesity-associated MC4R mutations, indicates that they all alter the activation of the receptor by the endogenous agonist α-MSH. To further examine the functional defects caused by childhood obesity-associated MC4R mutations, we developed a novel, sensitive technique to quantitatively analyze the effect of a mutation on MC4R cell surface expression. Using this method we analyzed the cell surface expression of all the 14 described childhood obesity-associated MC4R missense mutations. We demonstrate that 81.3% of childhood obesity-associated heterozygous MC4R mutations lead to intracellular retention of the receptor. This result has implications for the potential pharmacologic rescue of childhood obesity-associated MC4R mutations and for the treatment of patients presenting with this condition.