RESUMEN
Obesity is the most common nutritional disorder in Western society. Uncoupling protein-2 (UCP2) is a recently identified member of the mitochondrial transporter superfamily that is expressed in many tissues, including adipose tissue. Like its close relatives UCP1 and UCP3, UCP2 uncouples proton entry in the mitochondrial matrix from ATP synthesis and is therefore a candidate gene for obesity. We show here that a common G/A polymorphism in the UCP2 promoter region is associated with enhanced adipose tissue mRNA expression in vivo and results in increased transcription of a reporter gene in the human adipocyte cell line PAZ-6. In analyzing 340 obese and 256 never-obese middle-aged subjects, we found a modest but significant reduction in obesity prevalence associated with the less-common allele. We confirmed this association in a population-based sample of 791 middle-aged subjects from the same geographic area. Despite its modest effect, but because of its high frequency (approximately 63%), the more-common risk allele conferred a relatively large population-attributable risk accounting for 15% of the obesity in the population studied.
Asunto(s)
Proteínas de Unión al ADN , Predisposición Genética a la Enfermedad , Proteínas de Transporte de Membrana , Proteínas Mitocondriales , Obesidad/genética , Polimorfismo Genético , Regiones Promotoras Genéticas , Proteínas/genética , Receptores de Hidrocarburo de Aril , Regiones no Traducidas 3' , Tejido Adiposo/citología , Tejido Adiposo/fisiología , Adulto , Translocador Nuclear del Receptor de Aril Hidrocarburo , Sitios de Unión , Estudios de Casos y Controles , Línea Celular , Estudios Transversales , Femenino , Frecuencia de los Genes , Ligamiento Genético , Haplotipos/genética , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia , Canales Iónicos , Masculino , Persona de Mediana Edad , Secuencias Reguladoras de Ácidos Nucleicos , Factores de Transcripción/metabolismo , Proteína Desacopladora 2RESUMEN
Secretoneurin (SN) is a novel neuropeptide expressed in the central and peripheral nervous system as well as in various endocrine tissues. SN inhibits growth of aortic pulmonary and endothelial cells and is a potent chemoattractant for endothelial cells, skin fibroblasts and monocytes. We investigated here the presence of specific high affinity binding sites for SN on a target tissue. SN was iodinated with the Bolton-Hunter (BH) reagent and purified by isocratic reversed phase chromatography. Specific binding sites for 125I-BHSN were identified on human Mono Mac 6 cells, a monocytic cell line. Scatchard analysis revealed a single class of binding sites with a Kd value of 7.3 nM and a Bmax of 322 (fmol/mg protein). Competition studies demonstrated that the 15 C-terminal amino acids of SN could displace authentic SN, whereas shorter fragments were inactive. Other sensory neuropeptides like substance P, calcitonin gene-related peptide or galanin as well as the chemokine receptor ligand Rantes or the typical chemoattractant FMLP could not displace SN. Our studies demonstrate specific high affinity binding sites for SN on a monocytic cell line. Since SN exerts a potent chemotactic activity towards monocytes and increases cytosolic calcium in these cells, these binding sites might well represent a putative functional plasma membrane receptor for SN.
Asunto(s)
Monocitos/química , Monocitos/metabolismo , Neuropéptidos/metabolismo , Neuropéptidos/farmacología , Animales , Sitios de Unión/inmunología , Unión Competitiva/inmunología , Péptido Relacionado con Gen de Calcitonina/metabolismo , Péptido Relacionado con Gen de Calcitonina/farmacología , Cromograninas/metabolismo , Cromograninas/farmacología , Galanina/metabolismo , Galanina/farmacología , Humanos , Radioisótopos de Yodo , Leucemia Promielocítica Aguda , Monocitos/citología , Neuroblastoma , Proteínas/metabolismo , Ensayo de Unión Radioligante , Ratas , Receptores de Superficie Celular/metabolismo , Secretogranina II , Sustancia P/metabolismo , Sustancia P/farmacología , Células Tumorales Cultivadas/química , Células Tumorales Cultivadas/efectos de los fármacos , Células Tumorales Cultivadas/metabolismoRESUMEN
Secretoneurin is a recently-characterized neuropeptide derived from secretogranin II, a protein belonging to the class of chromogranins. We investigated the phylogeny of this peptide by immunoblotting and gel-filtration high performance liquid chromatography followed by radioimmunoassay of brain extracts of various species including chicken, lizard, frog and fish. In addition the amino acid sequence of secretoneurin from pig, hamster, rabbit, guinea-pig and chicken was established by reverse transcriptase polymerase chain reaction. Secretoneurin is strongly conserved during evolution, it is not only expressed in various mammalian species but found also in the brain of birds, reptiles, amphibians and fish. In all these species a significant or near complete processing of secretogranin II to secretoneurin was observed. These data provide significant evidence for the neuropeptide nature of the novel functional peptide.