Project description:In the mammalian neocortex, diverse projection neuron types are generated by the same pool of neural progenitors in sequential waves. How neuronal cell type specification is related to developmental timing remains unclear. To determine whether neural progenitor cell heterogenity correlates with neuronal type spcification, we performed single cell RNA sequencing analysis of the developing mouse neocortex (E10.5 through E18.5) by Drop-Seq. We uncovered cellular and molecular diversity among neuroepithelial cells, radial glial cells, intermediate progenitors and neuron types.
Project description:Neocortex expansion during evolution is linked to higher numbers of neurons thought to result from increased proliferative capacity and neurogenic potential of basal progenitors during development. Here, we show that EREG, encoding the growth factor EPIREGULIN, is expressed in the human developing neocortex, but not in the mouse neocortex. Addition of EPIREGULIN to the mouse neocortex increases proliferation of both major basal progenitor types, intermediate basal progenitors and basal radial glia, whereas ablation of EPIREGULIN in human cortical organoids reduces basal progenitor proliferation. Here, we analyzed gene expression changes upon addition of EPIREGULIN to the mouse neocortex for 24 hours using hemisphere rotation culture. We performed fluorescent activated cell sorting to isolate radial glia (RG), intermediate progenitor (IP) cells and neurons (N) based on the nuclear markers Sox2 and Tbr2, and expression of GFP in neurons isolated from a Tubb3::GFP mouse reporter line.
Project description:A specific subpopulation of neural progenitor cells, the basal radial glia cells (bRGCs) of the outer subventricular zone (OSVZ), are thought to have a key role in the evolutionary expansion of mammalian neocortex. In the developing lissencephalic mouse neocortex, bRGCs exist at low abundance and show significant molecular differences from bRGCs in developing gyrencephalic species. Here, we demonstrate that developing mouse medial neocortex, in contrast to the canonically studied lateral neocortex, exhibits an OSVZ and an abundance of bRGCs similar to that in developing gyrencephalic neocortex. Unlike bRGCs in developing mouse lateral neocortex, the bRGCs in medial neocortex exhibit human bRGC-like gene expression, including expression of Hopx, a human bRGC marker. Disruption of Hopx expression in mouse embryonic medial neocortex and forced Hopx expression in mouse embryonic lateral neocortex demonstrate that Hopx is required and sufficient, respectively, for a bRGC abundance as found in developing gyrencephalic neocortex. Taken together, our data identify a novel bRGC subpopulation in developing mouse medial neocortex that is highly related to bRGCs of developing gyrencephalic neocortex.
Project description:A specific subpopulation of neural progenitor cells, the basal radial glial cells (bRGCs) of the outer subventricular zone (OSVZ), are thought to have a key role in the evolutionary expansion of the mammalian neocortex. In the developing lissencephalic mouse neocortex, bRGCs exist at low abundance and show significant molecular differences from bRGCs in developing gyrencephalic species. Here, we demonstrate that the developing mouse medial neocortex (medNcx), in contrast to the canonically studied lateral neocortex (latNcx), exhibits an OSVZ and an abundance of bRGCs similar to that in developing gyrencephalic neocortex. Unlike bRGCs in developing mouse latNcx, the bRGCs in medNcx exhibit human bRGC-like gene expression, including expression of Hopx, a human bRGC marker. Disruption of Hopx expression in mouse embryonic medNcx and forced Hopx expression in mouse embryonic latNcx demonstrate that Hopx is required and sufficient, respectively, for a bRGC abundance as found in developing gyrencephalic neocortex. Taken together, our data identify a novel bRGC subpopulation in developing mouse medNcx that is highly related to bRGCs of developing gyrencephalic neocortex.
Project description:Proper neural progenitor behavior in conjunction with orderly vasculature formation is fundamental to the development of the neocortex. However, the mechanisms coordinating neural progenitor behavior and vessel growth remain largely elusive. Here we show that robust metabolic production of lactate by radial glial progenitors (RGPs) co-regulates vascular development and RGP division behavior in the developing mouse neocortex. RGPs undergo a highly organized lineage progression program to produce diverse neural progeny. Systematic single cell metabolic state analysis revealed that RGPs and their progeny exhibit distinct metabolic features associated with specific cell types and lineage progression statuses. Symmetrically dividing, proliferative RGPs preferentially express a cohort of genes that support glucose uptake and anaerobic glycolysis. Consequently, they consume glucose in anaerobic metabolism and produce a high level of lactate, which promotes vessel growth. Moreover, lactate production enhances RGP proliferation by maintaining mitochondrial length. Together, these results suggest that specific metabolic states and metabolites coordinately regulate vasculature formation and progenitor behavior in neocortical development.
Project description:The evolutionary expansion of the human neocortex reflects increased amplification of basal progenitors in the subventricular zone, producing more neurons during fetal corticogenesis. Here, we analyze the transcriptomes of distinct progenitor subpopulations isolated by a novel approach from developing mouse and human neocortex. We identify 56 genes preferentially expressed in human apical and basal radial glia that lack mouse orthologs. Among these, ARHGAP11B has the highest degree of radial glia-specific expression. ARHGAP11B arose from partial duplication of the Rho GTPase-activating-protein–encoding ARHGAP11A on the human lineage after separation from the chimpanzee lineage. Expression of ARHGAP11B in embryonic mouse neocortex promotes basal progenitor generation and self-renewal, and can increase cortical plate area and induce gyrification. Hence, ARHGAP11B may have contributed to evolutionary expansion of human neocortex. Gene expression profiles of mouse and human purified neocortical progenitor types and neurons were generated by RNA-seq and analyzed including inter- and intra-species comparison.
Project description:The generation of neocortical neurons from neural progenitor cells (NPCs) is primarily controlled by transcription factors binding to DNA in the context of chromatin. To understand the complex layer of regulation that orchestrates different NPC types from the same DNA sequence, epigenome maps with cell type resolution are required. Here we present genome-wide histone methylation maps for distinct neural cell populations in the developing mouse neocortex. Using different chromatin features, we identify potential novel regulators of cortical NPCs available for future exploration. Moreover, we identify extensive H3K27me3 changes between NPC subtypes coinciding with major developmental and cell biological transitions. Interestingly, we detect dynamic H3K27me3 changes on promoters of several crucial transcription factors, including the basal progenitor regulator Eomes. We used catalytically inactive Cas9 fused with the histone methyltransferase Ezh2 to edit H3K27me3 at the Eomes locus in vivo, which results in reduced Tbr2 expression and lower basal progenitor abundance, underscoring the relevance of dynamic H3K27me3 changes during neocortex development. Taken together, we provide a rich resource of neocortical histone methylation and outline an approach to investigate its contribution to the regulation of selected genes during neocortical development.
Project description:The generation of neocortical neurons from neural progenitor cells (NPCs) is primarily controlled by transcription factors binding to DNA in the context of chromatin. To understand the complex layer of regulation that orchestrates different NPC types from the same DNA sequence, epigenome maps with cell type resolution are required. Here we present genome-wide histone methylation maps for distinct neural cell populations in the developing mouse neocortex. Using different chromatin features, we identify potential novel regulators of cortical NPCs available for future exploration. Moreover, we identify extensive H3K27me3 changes between NPC subtypes coinciding with major developmental and cell biological transitions. Interestingly, we detect dynamic H3K27me3 changes on promoters of several crucial transcription factors, including the basal progenitor regulator Eomes. We used catalytically inactive Cas9 fused with the histone methyltransferase Ezh2 to edit H3K27me3 at the Eomes locus in vivo, which results in reduced Tbr2 expression and lower basal progenitor abundance, underscoring the relevance of dynamic H3K27me3 changes during neocortex development. Taken together, we provide a rich resource of neocortical histone methylation and outline an approach to investigate its contribution to the regulation of selected genes during neocortical development.