RESUMEN
Expression of the basic helix-loop-helix (bHLH) transcription factor Neurogenin1 (Neurog1) coincides with the emergence of the cerebellum and Neurog1-expressing progenitors are fated to become Purkinje cells and later interneurons. However, the gene regulatory functions of Neurog1 in cerebellar development have not been characterized. We performed a genome-wide analysis of gene expression in the cerebellar primordium of E11.5 Neurog1 null (Neurog1-/-) mice to identify the Neurog1 transcriptome in the emerging cerebellum. This screen identified 117 genes differentially enriched in Neurog1-/- versus control sample sets with a high presence of gene sets enriched for functions in nervous system development. Hierarchical clustering revealed complete stratification of differentially expressed genes based on Neurog1 gene deletion status. In silico analysis of promoter regions identifies high probability Neurog1 regulatory (E-box) binding sites in 94 of the 117 differentially expressed genes and Pax6 binding motifs in 25 of these 94 promoters. Our data provide a framework for investigating Neurog1 transcriptional programs in early cerebellar development and suggest functional Neurog1-Pax6 cross-talk in the activation of downstream targets.
Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Cerebelo/embriología , Proteínas del Ojo/genética , Regulación del Desarrollo de la Expresión Génica/genética , Proteínas de Homeodominio/genética , Proteínas del Tejido Nervioso/genética , Neurogénesis/genética , Factores de Transcripción Paired Box/genética , Proteínas Represoras/genética , Animales , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Desarrollo Embrionario/genética , Proteínas del Ojo/metabolismo , Expresión Génica , Proteínas de Homeodominio/metabolismo , Ratones , Ratones Noqueados , Proteínas del Tejido Nervioso/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Factor de Transcripción PAX6 , Factores de Transcripción Paired Box/metabolismo , Proteínas Represoras/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
The basic helix-loop-helix (bHLH) transcription factors Ptf1a and Math1 are necessary for the specification of gamma-aminobutyric acid-ergic and glutamatergic cell lineages in the cerebellum, respectively. Recent evidence suggests cascades of bHLH factor activities drive cell type specificity in Ptf1a(+ve) and Math1(+ve) lineages. In this manuscript, we reveal cell lineages in the cerebellar cortex but not deep cerebellar nuclei express the pro-neural bHLH factor Neurogenin1 (Ngn1). Ngn1 is expressed in ventricular zone progenitors and in newly generated neurons in the caudal cerebellar primordium. In later embryonic and postnatal developmental stages, Ngn1 is expressed in progenitors and in migrating interneurons in the prospective white matter. Transgenic fate-mapping reveals Ngn1 reporter-gene expression in Purkinje cells, multiple inhibitory interneuron cell types, and in unipolar brush cells of the cortex. The data suggest Ngn1 is a component of the bHLH factor code regulating cell type specification in the cerebellar cortex.