RESUMO
Melanocortin receptor accessory protein 2 (MRAP2) is a transmembrane accessory protein predominantly expressed in the brain. Both global and brain-specific deletion of Mrap2 in mice results in severe obesity. Loss-of-function MRAP2 mutations have also been associated with obesity in humans. Although MRAP2 has been shown to interact with MC4R, a G protein-coupled receptor with an established role in energy homeostasis, appetite regulation and lipid metabolism, the mechanisms through which loss of MRAP2 causes obesity remains uncertain. In this study, we used two independently derived lines of Mrap2 deficient mice (Mrap2(tm1a/tm1a)) to further study the role of Mrap2 in the regulation of energy balance and peripheral lipid metabolism. Mrap2(tm1a/tm1a) mice have a significant increase in body weight, with increased fat and lean mass, but without detectable changes in food intake or energy expenditure. Transcriptomic analysis showed significantly decreased expression of Sim1, Trh, Oxt and Crh within the hypothalamic paraventricular nucleus of Mrap2(tm1a/tm1a) mice. Circulating levels of both high-density lipoprotein and low-density lipoprotein were significantly increased in Mrap2 deficient mice. Taken together, these data corroborate the role of MRAP2 in metabolic regulation and indicate that, at least in part, this may be due to defective central melanocortin signalling.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Colesterol/sangue , Metabolismo Energético/genética , Proteínas Modificadoras da Atividade de Receptores/metabolismo , Proteínas Repressoras/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Animais , Ansiedade/genética , Ansiedade/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Comportamento Animal/fisiologia , Peso Corporal/genética , Hormônio Liberador da Corticotropina/genética , Hormônio Liberador da Corticotropina/metabolismo , Ingestão de Alimentos/genética , Metabolismo dos Lipídeos/genética , Camundongos , Camundongos Knockout , Atividade Motora/genética , Neurônios/metabolismo , Ocitocina/genética , Ocitocina/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , Proteínas Modificadoras da Atividade de Receptores/genética , Proteínas Repressoras/genética , Hormônio Liberador de Tireotropina/genética , Hormônio Liberador de Tireotropina/metabolismoRESUMO
The ability to differentiate genetically modified mouse embryonic stem (ES) cells into functional macrophages provides a potentially attractive resource to study host-pathogen interactions without the need for animal experimentation. This is particularly useful in instances where the gene of interest is essential and a knockout mouse is not available. Here we differentiated mouse ES cells into macrophages in vitro and showed, through a combination of flow cytometry, microscopic imaging, and RNA-Seq, that ES cell-derived macrophages responded to S. Typhimurium, in a comparable manner to mouse bone marrow derived macrophages. We constructed a homozygous mutant mouse ES cell line in the Traf2 gene that is known to play a role in tumour necrosis factor-α signalling but has not been studied for its role in infections or response to Toll-like receptor agonists. Interestingly, traf2-deficient macrophages produced reduced levels of inflammatory cytokines in response to lipopolysaccharide (LPS) or flagellin stimulation and exhibited increased susceptibility to S. Typhimurium infection.
Assuntos
Diferenciação Celular/genética , Macrófagos/metabolismo , Células-Tronco Embrionárias Murinas/metabolismo , Fator 2 Associado a Receptor de TNF/biossíntese , Animais , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento/genética , Humanos , Lipopolissacarídeos/toxicidade , Macrófagos/efeitos dos fármacos , Camundongos , Células-Tronco Embrionárias Murinas/citologia , Salmonella typhimurium/patogenicidade , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Fator 2 Associado a Receptor de TNF/genética , Receptores Toll-Like/metabolismo , Fator de Necrose Tumoral alfa/genéticaRESUMO
The methyl CpG binding proteins (MeCP1 and MeCP2) are a class of proteins that bind to templates containing symmetrically methylated CpGs. Using an interspecific backcross segregating a number of X-linked markers, we have localized the Mecp2 gene in mouse to the X chromosome close to the microsatellite marker DXMit1. Detailed physical mapping utilizing an available YAC contig encompassing the DXMit1 locus has localized the Mecp2 gene to a 40-kb region between the L1cam and the Rsvp loci, indicating the probable position of a homologue on the human X chromosome.
Assuntos
Proteínas Cromossômicas não Histona , Mapeamento Cromossômico , Proteínas de Ligação a DNA/genética , Proteínas Repressoras , Cromossomo X , Animais , Sequência de Bases , Cromossomos Artificiais de Levedura , Cruzamentos Genéticos , Primers do DNA/genética , Feminino , Humanos , Masculino , Proteína 2 de Ligação a Metil-CpG , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Muridae , Especificidade da EspécieRESUMO
DNA methyltransferase is needed for normal development, perhaps because DNA methylation plays a part in the control of gene activity. It is clear that the methylation of promoters often leads to repression of transcription. Studies of the mechanism suggest that repression may either result from the direct effects of methylation on transcription factors, or may be indirectly caused by repressor proteins that bind to methylated DNA. Current evidence suggests that both mechanisms can be involved.
