RESUMO
The control of gene expression in neural stem cells is key to understanding their developmental and therapeutic potential, yet we know little of the transcriptional mechanisms that underlie their differentiation. Recent evidence has implicated the RE1 silencing transcription factor (REST) in neuronal differentiation. However, the means by which REST regulates transcription in neural stem cells remain unclear. Here, we show that REST recruits distinct corepressor platforms in neural stem cells. REST is able to both silence and repress neuronal genes in embryonic hippocampal neural stem cells by creating a chromatin environment that contains both repressive local epigenetic signature (characterized by low levels of histones H4 and H3K9 acetylation and elevated dimethylation of H3K9) and H3K4 methylation, which are characteristic of gene activation. Furthermore, inhibition of REST function leads to activation of several neuron-specific genes but does not lead to overt formation of mature neurons, supporting the notion that REST regulates part, but not all, of the neuronal differentiation program.
Assuntos
Cromatina/metabolismo , Células-Tronco Embrionárias/metabolismo , Hipocampo/citologia , Hipocampo/embriologia , Neurônios/citologia , Neurônios/metabolismo , Proteínas Repressoras/metabolismo , Fatores de Transcrição/metabolismo , Animais , Bovinos , Diferenciação Celular , Imunoprecipitação da Cromatina , Proteínas Correpressoras , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Células-Tronco Embrionárias/citologia , Células-Tronco Embrionárias/enzimologia , Inativação Gênica , Hipocampo/enzimologia , Histona Desacetilases/metabolismo , Histonas/metabolismo , Humanos , Camundongos , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Neurônios/enzimologia , Ligação Proteica , Transporte Proteico , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Sequências Reguladoras de Ácido Nucleico/genética , Proteínas Repressoras/genética , Complexo Correpressor Histona Desacetilase e Sin3 , Fatores de Transcrição/genética , Tubulina (Proteína)/metabolismoRESUMO
Differentiation of pluripotent embryonic stem (ES) cells through multipotent neural stem (NS) cells into differentiated neurons is accompanied by wholesale changes in transcriptional programs. One factor that is present at all three stages and a key to neuronal differentiation is the RE1-silencing transcription factor (REST/NRSF). Here, we have used a novel chromatin immunoprecipitation-based cloning strategy (SACHI) to identify 89 REST target genes in ES cells, embryonic hippocampal NS cells and mature hippocampus. The gene products are involved in all aspects of neuronal function, especially neuronal differentiation, axonal growth, vesicular transport and release, and ionic conductance. Most target genes are silent or expressed at low levels in ES and NS cells, but are expressed at much higher levels in hippocampus. These data indicate that the REST regulon is specific to each developmental stage and support the notion that REST plays distinct roles in regulating gene expression in pluripotent ES cells, multipotent NS cells, and mature neurons.