RESUMO
Master transcription factors have the ability to direct and reverse cellular identities, and consequently their genes must be subject to particular transcriptional control. However, it is unclear which molecular processes are responsible for impeding their activation and safeguarding cellular identities. Here we show that the targeting of dCas9-VP64 to the promoter of the master transcription factor Sox1 results in strong transcript and protein up-regulation in neural progenitor cells (NPCs). This gene activation restores lost neuronal differentiation potential, which substantiates the role of Sox1 as a master transcription factor. However, despite efficient transactivator binding, major proportions of progenitor cells are unresponsive to the transactivating stimulus. By combining the transactivation domain with epigenome editing we find that among a series of euchromatic processes, the removal of DNA methylation (by dCas9-Tet1) has the highest potential to increase the proportion of cells activating foreign master transcription factors and thus breaking down cell identity barriers.
Assuntos
Diferenciação Celular/genética , Reprogramação Celular/genética , Epigênese Genética , Células-Tronco Neurais/fisiologia , Fatores de Transcrição SOXB1/metabolismo , Animais , Sistemas CRISPR-Cas/genética , Linhagem Celular , Metilação de DNA/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Edição de Genes/métodos , Regulação da Expressão Gênica , Camundongos , Neuroglia/citologia , Neuroglia/fisiologia , Regiões Promotoras Genéticas/genética , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , RNA Guia de Cinetoplastídeos/genética , RNA Guia de Cinetoplastídeos/metabolismo , Fatores de Transcrição SOXB1/genética , Transcrição Gênica/genéticaRESUMO
Maternal diet during pregnancy can impact maternal behavior as well as the intrauterine environment, playing a critical role in programming offspring's physiology. In a preliminary study, we found a strong association between high-fat diet (HFD) during pregnancy and increased cannibalistic episodes and dams' mortality during late pregnancy and parturition. Based upon these data, we hypothesized that HFD during pregnancy could negatively affect neuroendocrine and metabolic regulations occurring during the final stages of pregnancy, thereby disrupting maternal behavior. To test this hypothesis, female C57BL/6J mice were fed HFD or control diet for 11 weeks until three days before the expected delivery date. Basal corticosterone plasma levels and brain levels of c-Fos were measured both before and after delivery, in addition to leptin levels in the adipose tissue. Dam's emotional behavior and social anxiety, in addition to locomotor activity were assessed before parturition. Data show that HFD led to aberrant maternal behavior, dams being characterized by behaviors related to aggression toward an unfamiliar social stimulus in the social avoidance test, in addition to decreased locomotor activity. Neural activity in HFD dams was reduced in the olfactory bulbs, a crucial brain region for social and olfactory recognition hence essential for maternal behavior. Furthermore, HFD feeding resulted in increased circulating levels of maternal corticosterone and decreased levels of leptin. In addition, the activity of the protective 11ß-dehydrogenase-2 (11ß-HSD-2) barrier in the placenta was decreased together with 11ß-dehydrogenase-1 (11ß-HSD-1) gene expression. Overall, these data suggest that HFD acts as a stressful challenge during pregnancy, impairing the neuroendocrine system and the neural activity of brain regions involved in the processing of relevant olfactory stimuli, with negative consequences on maternal physiology and behavior.