RESUMEN
We previously reported children homozygous for two MC3R sequence variants (C17A+G241A) have greater fat mass than controls. Here we show, using homozygous knock-in mouse models in which we replace murine Mc3r with wild-type human (MC3R(hWT/hWT)) and double-mutant (C17A+G241A) human (MC3R(hDM/hDM)) MC3R, that MC3R(hDM/hDM) have greater weight and fat mass, increased energy intake and feeding efficiency, but reduced length and fat-free mass compared with MC3R(hWT/hWT). MC3R(hDM/hDM) mice do not have increased adipose tissue inflammatory cell infiltration or greater expression of inflammatory markers despite their greater fat mass. Serum adiponectin levels are increased in MC3R(hDM/hDM) mice and MC3R(hDM/hDM) human subjects. MC3R(hDM/hDM) bone- and adipose tissue-derived mesenchymal stem cells (MSCs) differentiate into adipocytes that accumulate more triglyceride than MC3R(hWT/hWT) MSCs. MC3R(hDM/hDM) impacts nutrient partitioning to generate increased adipose tissue that appears metabolically healthy. These data confirm the importance of MC3R signalling in human metabolism and suggest a previously-unrecognized role for the MC3R in adipose tissue development.
Asunto(s)
Obesidad/metabolismo , Receptor de Melanocortina Tipo 3/metabolismo , Adipocitos/metabolismo , Adiponectina/metabolismo , Tejido Adiposo/metabolismo , Animales , Modelos Animales de Enfermedad , Ingestión de Alimentos , Metabolismo Energético , Grasas/metabolismo , Técnicas de Sustitución del Gen , Humanos , Leptina/metabolismo , Ratones , Obesidad/genética , Obesidad/fisiopatología , Receptor de Melanocortina Tipo 3/genéticaRESUMEN
To understand the molecular mechanisms underlying the development of dyslipidemia and lipodystrophy that occurs after administration of aspartic acid protease inhibitors, we examined transcriptional profiles using cDNA microarrays in 3T3-L1 adipocytes exposed to 10 micromol/l ritonavir for 2-21 days. The expression levels of approximately 12,000 transcripts were assessed using the MgU74Av2 mouse microarray chip. Ritonavir altered gene expression of inflammatory cytokines, stress response genes localized to endoplasmic reticulum, oxidative stress genes, apoptosis-related genes, and expression of genes involved in cell adhesion and extracellular matrix remodeling. Microarray analysis also identified a novel gene downregulated by ritonavir, Cidea, whose expression levels may affect free-fatty acid metabolism. These changes suggest a unique, stress-related pattern in adipocytes induced by chronic exposure to the protease inhibitor, ritonavir.
Asunto(s)
Adipocitos/efectos de los fármacos , Inhibidores de la Proteasa del VIH/farmacología , Ritonavir/farmacología , Transcripción Genética/efectos de los fármacos , Células 3T3-L1 , Adipocitos/metabolismo , Animales , Apoptosis/efectos de los fármacos , Apoptosis/genética , Adhesión Celular/efectos de los fármacos , Adhesión Celular/genética , Citocinas/genética , Matriz Extracelular/efectos de los fármacos , Matriz Extracelular/genética , Perfilación de la Expresión Génica/métodos , Regulación de la Expresión Génica/efectos de los fármacos , Síndrome de Lipodistrofia Asociada a VIH/genética , Síndrome de Lipodistrofia Asociada a VIH/metabolismo , Humanos , Metabolismo de los Lípidos/efectos de los fármacos , Metabolismo de los Lípidos/genética , Ratones , Análisis de Secuencia por Matrices de Oligonucleótidos , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/genética , ARN Mensajero/metabolismo , Factores de TiempoRESUMEN
Eph receptors and ephrins are dynamically expressed in a wide range of regions of the vertebrate during embryogenesis. The dorsal mesencephalon appears to be segmented into two broad regions demarcated by the mutually exclusive expression of EphA receptors and ephrinA ligands. It is of considerable interest to elucidate how these expression domains are established in the development of the mesencephalon. In this study, we used a transgenic approach to define the cis-acting DNA regulatory elements involved in the anterior mesencephalon-specific expression of the mouse ephA8 gene. Our analyses of the temporal and spatial expression patterns of various ephA8/lacZ gene fusions in transgenic mice revealed that the 10-kb genomic DNA 5' immediately upstream of the ephA8 coding sequence is capable of directing lacZ expression in an ephA8-specific manner. Further deletion analyses of the ephA8 genomic region led to the identification of a 1-kb enhancer region, which directs expression in the embryo to the anterior region of the developing midbrain. This ephA8-specific regulatory DNA sequences can now be used in biochemical analyses to identify proteins modulating the anterior differentiation of the optic tectum, and in functional analyses to direct the expression of other developmentally important genes to this region.