RESUMO
While microRNAs have emerged as an important component of gene regulatory networks, it remains unclear how microRNAs collaborate with transcription factors in the gene networks that determines neuronal cell fate. Here we show that in the developing spinal cord, the expression of miR-218 is directly upregulated by the Isl1-Lhx3 complex, which drives motor neuron fate. Inhibition of miR-218 suppresses the generation of motor neurons in both chick neural tube and mouse embryonic stem cells, suggesting that miR-218 plays a crucial role in motor neuron differentiation. Results from unbiased RISC-trap screens, in vivo reporter assays and overexpression studies indicated that miR-218 directly represses transcripts that promote developmental programs for interneurons. In addition, we found that miR-218 activity is required for Isl1-Lhx3 to effectively induce motor neurons and suppress interneuron fates. Together our results reveal an essential role of miR-218 as a downstream effector of the Isl1-Lhx3 complex in establishing motor neuron identity.
Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Proteínas com Homeodomínio LIM/genética , MicroRNAs/genética , Neurônios Motores/citologia , Tubo Neural/embriologia , Neurogênese/genética , Medula Espinal/embriologia , Fatores de Transcrição/genética , Animais , Embrião de Galinha , Eletroporação , Células HEK293 , Humanos , Proteínas com Homeodomínio LIM/metabolismo , Camundongos , Células-Tronco Embrionárias Murinas , Tubo Neural/citologia , Reação em Cadeia da Polimerase em Tempo Real , Medula Espinal/citologia , Fatores de Transcrição/metabolismo , Regulação para CimaRESUMO
BACKGROUND: Many preclinical studies have demonstrated age-related differential sensitivity to various effects of ethanol between adolescent and adult animals. However, published data addressing possible differences in ethanol's motivational effects are sparse, particularly in mice. The present study examined age-related differences in the conditioned rewarding effects of ethanol in DBA/2J mice. METHODS: In the first experiment an unbiased place conditioning procedure was used to determine the rewarding effects of 2 g/kg ethanol in adult and adolescent DBA/2J mice. In a subsequent place conditioning experiment, the effects of 2 and 4 g/kg were assessed in adolescent mice. RESULTS: Adolescents demonstrated a place preference with the high dose of 4 g/kg but not with a more moderate dose of 2 g/kg. In contrast, 2 g/kg was sufficient to produce place preference in adult mice. CONCLUSIONS: Adolescents are less sensitive than adults to the rewarding effects of ethanol but can experience reward with high doses. These results extend the current literature on ethanol's effects in adolescent animals.
