RESUMO
During corticogenesis, distinct classes of neurons are born from progenitor cells located in the ventricular and subventricular zones, from where they migrate towards the pial surface to assemble into highly organized layer-specific circuits. However, the precise and coordinated transcriptional network activity defining neuronal identity is still not understood. Here, we show that genetic depletion of the basic helix-loop-helix (bHLH) transcription factor E2A splice variant E47 increased the number of Tbr1-positive deep layer and Satb2-positive upper layer neurons at E14.5, while depletion of the alternatively spliced E12 variant did not affect layer-specific neurogenesis. While ChIP-Seq identified a big overlap for E12- and E47-specific binding sites in embryonic NSCs, including sites at the cyclin-dependent kinase inhibitor (CDKI) Cdkn1c gene locus, RNA-Seq revealed a unique transcriptional regulation by each splice variant. E47 activated the expression of the CDKI Cdkn1c through binding to a distal enhancer. Finally, overexpression of E47 in embryonic NSCs in vitro impaired neurite outgrowth, and overexpression of E47 in vivo by in utero electroporation disturbed proper layer-specific neurogenesis and upregulated p57(KIP2) expression. Overall, this study identifies E2A target genes in embryonic NSCs and demonstrates that E47 regulates neuronal differentiation via p57(KIP2).
Assuntos
Processamento Alternativo/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Diferenciação Celular/genética , Córtex Cerebral/embriologia , Inibidor de Quinase Dependente de Ciclina p57/genética , Neurônios/citologia , Fator 3 de Transcrição/metabolismo , Animais , Sequência de Bases , Sítios de Ligação/genética , Ciclo Celular/genética , Córtex Cerebral/citologia , Cromatina/metabolismo , Inibidor de Quinase Dependente de Ciclina p57/metabolismo , Elementos Facilitadores Genéticos/genética , Regulação da Expressão Gênica no Desenvolvimento , Camundongos Endogâmicos C57BL , Células-Tronco Neurais/citologia , Células-Tronco Neurais/metabolismo , Neurogênese/genética , Neurônios/metabolismo , Ligação Proteica , Fator 3 de Transcrição/deficiência , Transcrição GênicaRESUMO
The protein inhibitor of activated STAT1 (PIAS1) plays important roles in regulating virus-induced chronic hepatitis, but the interaction between hepatitis B virus (HBV) and hPIAS1 is not clear. Our aim was to verify if HBV encoding proteins enhance the transcription of hPIAS1 and which cis-elements and transcription factors were involved in the mechanism. In order to do, so a series of molecular biological methods, along with functional and histological studies, were performed. We found that the HBV surface protein (HBs) enhanced hPIAS1 transcription through the activities of TAL1, E47, myogenin (MYOG), and NFI, dependent on the activation of p38MAPK and ERK signaling pathways in vitro, which might contribute to the ineffectiveness of treatment in CHB patients. Furthermore, liver samples from patients with high HBsAg levels and HBV DNA displayed increased hPIAS1 expression and high levels of TAL1, E47, MYOG, and NFI, compared to those patients with low HBsAg levels and HBV DNA, and healthy controls. These findings suggest that the HBs protein-induced hPIAS1 transcription requires TAL1, E47, MYOG, NFI, and MAPK signal pathways. It provides new potential targets for antiviral therapeutic strategies for controlling HBV-associated diseases.
