RESUMO
Exome sequencing studies have identified multiple genes harboring de novo loss-of-function (LoF) variants in individuals with autism spectrum disorders (ASD), including TBR1, a master regulator of cortical development. We performed ChIP-seq for TBR1 during mouse cortical neurogenesis and show that TBR1-bound regions are enriched adjacent to ASD genes. ASD genes were also enriched among genes that are differentially expressed in Tbr1 knockouts, which together with the ChIP-seq data, suggests direct transcriptional regulation. Of the nine ASD genes examined, seven were misexpressed in the cortices of Tbr1 knockout mice, including six with increased expression in the deep cortical layers. ASD genes with adjacent cortical TBR1 ChIP-seq peaks also showed unusually low levels of LoF mutations in a reference human population and among Icelanders. We then leveraged TBR1 binding to identify an appealing subset of candidate ASD genes. Our findings highlight a TBR1-regulated network of ASD genes in the developing neocortex that are relatively intolerant to LoF mutations, indicating that these genes may play critical roles in normal cortical development.
Assuntos
Transtorno do Espectro Autista/genética , Proteínas de Ligação a DNA/genética , Neocórtex/fisiopatologia , Neurogênese/genética , Animais , Transtorno do Espectro Autista/fisiopatologia , Modelos Animais de Doenças , Exoma/genética , Regulação da Expressão Gênica , Técnicas de Inativação de Genes , Humanos , Camundongos , Mutação , Neocórtex/crescimento & desenvolvimento , Neurônios/metabolismo , Neurônios/patologia , Fatores de Risco , Proteínas com Domínio TRESUMO
Fezf1 and Fezf2 are highly conserved transcription factors that were first identified by their specific expression in the anterior neuroepithelium of Xenopus and zebrafish embryos. These proteins share an N-terminal domain with homology to the canonical engrailed repressor motif and a C-terminal DNA binding domain containing six C2H2 zinc-finger repeats. Over a decade of study indicates that the Fez proteins play critical roles during nervous system development in species as diverse as fruit flies and mice. Herein we discuss recent progress in understanding the functions of Fezf1 and Fezf2 in neurogenesis and cell fate specification during mammalian nervous system development. Going forward we believe that efforts should focus on understanding how expression of these factors is precisely regulated, and on identifying target DNA sequences and interacting partners. Such knowledge may reveal the mechanisms by which Fezf1 and Fezf2 accomplish both independent and redundant functions across diverse tissue and cell types.
Assuntos
Neurogênese , Córtex Olfatório/embriologia , Prosencéfalo/embriologia , Fatores de Transcrição/fisiologia , Animais , Padronização Corporal , Evolução Molecular , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Células-Tronco Neurais/fisiologia , Córtex Olfatório/citologia , Córtex Olfatório/metabolismo , Prosencéfalo/citologia , Prosencéfalo/metabolismo , Proteínas RepressorasRESUMO
We recently published genetic lineage-tracing experiments using the Fezf2 and Cux2 loci. These experiments demonstrated that at both the clonal and population levels Fezf2(+) RGCs are multipotent and that at the population level Cux2(+) RGCs are multipotent. Here, we extend our work on the lineages of Fezf2(+) and Cux2(+) RGCs. Clonal analysis of E10.5 neocortical progenitors suggests that most, if not all, Cux2(+) and Fezf2(+) RGCs generate diverse projection neuron subtypes located throughout layers 2-6. These results support our previous conclusion that both Fezf2(+) and Cux2(+) RGCs are multipotent neocortical progenitors. This Matters Arising Response paper addresses the Gil-Sanz et al. (2015) Matters Arising paper, published concurrently in Neuron.
Assuntos
Linhagem da Célula/fisiologia , Proteínas de Homeodomínio/metabolismo , Neocórtex/metabolismo , Neurônios/citologia , Regulação da Expressão Gênica no Desenvolvimento/genética , Células-Tronco Multipotentes/citologia , Neocórtex/citologia , Proteínas do Tecido Nervoso/metabolismo , Neurogênese/fisiologia , Neurônios/metabolismo , OligodendrogliaRESUMO
BACKGROUND: The genetic programs required for development of the cerebral cortex are under intense investigation. However, non-coding DNA elements that control the expression of developmentally important genes remain poorly defined. Here we investigate the regulation of Fezf2, a transcription factor that is necessary for the generation of deep-layer cortical projection neurons. RESULTS: Using a combination of chromatin immunoprecipitation followed by high throughput sequencing (ChIP-seq) we mapped the binding of four deep-layer-enriched transcription factors previously shown to be important for cortical development. Building upon this we characterized the activity of three regulatory regions around the Fezf2 locus at multiple stages throughout corticogenesis. We identified a promoter that was sufficient for expression in the cerebral cortex, and enhancers that drove reporter gene expression in distinct forebrain domains, including progenitor cells and cortical projection neurons. CONCLUSIONS: These results provide insight into the regulatory logic controlling Fezf2 expression and further the understanding of how multiple non-coding regulatory domains can collaborate to control gene expression in vivo.
Assuntos
Córtex Cerebral/embriologia , Córtex Cerebral/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas do Tecido Nervoso/genética , Elementos Reguladores de Transcrição , Animais , Córtex Cerebral/citologia , Elementos Facilitadores Genéticos , Camundongos , Camundongos TransgênicosRESUMO
Progenitor cells in the cerebral cortex sequentially generate distinct classes of projection neurons. Recent work suggests the cortex may contain intrinsically fate-restricted progenitors marked by expression of Cux2. However, the heterogeneity of the neocortical ventricular zone as well as the contribution of lineage-restricted progenitors to the overall cortical neurogenic program remains unclear. Here, we utilize in vivo genetic fate mapping to demonstrate that Fezf2-expressing radial glial cells (RGCs) exist throughout cortical development and sequentially generate all major projection neuron subtypes and glia. Moreover, we show that the vast majority of CUX2⺠cells in the VZ and SVZ are migrating interneurons derived from the subcortical telencephalon. Examination of the embryonic cortical progenitor population demonstrates that Cux2⺠RGCs generate both deep- and upper-layer projection neurons. These results identify Fezf2⺠radial glial cells as a multipotent neocortical progenitor and suggest that the existence, and molecular identity, of laminar-fate-restricted RGCs awaits further investigation.
Assuntos
Astrócitos/metabolismo , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Células-Tronco Multipotentes/fisiologia , Neocórtex/citologia , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Oligodendroglia/metabolismo , Fatores Etários , Animais , Animais Recém-Nascidos , Diferenciação Celular , Movimento Celular/genética , Proteínas de Ligação a DNA/genética , Embrião de Mamíferos , Endopeptidases/genética , Endopeptidases/metabolismo , Lateralidade Funcional , Proteínas de Fluorescência Verde/genética , Proteínas de Homeodomínio/genética , Camundongos , Camundongos Transgênicos , Proteínas do Tecido Nervoso/genética , Fatores de Transcrição/metabolismoRESUMO
The murine olfactory system consists of main and accessory systems that perform distinct and overlapping functions. The main olfactory epithelium (MOE) is primarily involved in the detection of volatile odorants, while neurons in the vomeronasal organ (VNO), part of the accessory olfactory system, are important for pheromone detection. During development, the MOE and VNO both originate from the olfactory pit; however, the mechanisms regulating development of these anatomically distinct organs from a common olfactory primordium are unknown. Here we report that two closely related zinc-finger transcription factors, FEZF1 and FEZF2, regulate the identity of MOE sensory neurons and are essential for the survival of VNO neurons respectively. Fezf1 is predominantly expressed in the MOE while Fezf2 expression is restricted to the VNO. In Fezf1-deficient mice, olfactory neurons fail to mature and also express markers of functional VNO neurons. In Fezf2-deficient mice, VNO neurons degenerate prior to birth. These results identify Fezf1 and Fezf2 as important regulators of olfactory system development and sensory neuron identity.