Project description:The human neocortex is created from diverse progenitors that are intermixed with multiple cell types in the prenatal germinal zones. These progenitors have been difficult to profile with unbiased transcriptomics since progenitors-particularly radial glia (RG)-are rare cell types, defined by a combination of intracellular markers, position and morphology. To circumvent these problems, we developed a method called FRSCR for transcriptome profiling of individual fixed, stained, and sorted cells. After validation of FRSCR with human embryonic stem cells, we profiled primary human RG that constitute only 1% of the mid-gestation cortex. These data showed that RG could be classified into ventricle zone-enriched RG (vRG) that expressed ANXA1 and CRYAB, and outer subventricular zone-localized RG (oRG) that expressed HOPX. Our study identified the first markers and molecular profiles of vRG and oRG cells, and provides an essential step for understanding molecular networks that control the development and lineage of human neocortical progenitors. Furthermore, FRSCR allows targeted single-cell transcriptomic profiling of many tissues that currently lack live-cell markers.
Project description:The diverse progenitors that give rise to the human neocortex have been difficult to characterize because progenitors, particularly radial glia (RG), are rare and are defined by a combination of intracellular markers, position and morphology. To circumvent these problems, we developed Fixed and Recovered Intact Single-cell RNA (FRISCR), a method for profiling the transcriptomes of individual fixed, stained and sorted cells. Using FRISCR, we profiled primary human RG that constitute only 1% of the midgestation cortex and classified them as ventricular zone-enriched RG (vRG) that express ANXA1 and CRYAB, and outer subventricular zone-localized RG (oRG) that express HOPX. Our study identified vRG and oRG markers and molecular profiles, an essential step for understanding human neocortical progenitor development. FRISCR allows targeted single-cell profiling of any tissues that lack live-cell markers.
Project description:Since the discovery of radial glia as the source of neurons, their heterogeneity in regard to neurogenesis has been described by clonal and time-lapse analysis in vitro. However, the molecular determinants specifying neurogenic radial glia differently from radial glia that mostly self-renew remain ill-defined. Here, we isolated two radial glial subsets that co-exist at mid-neurogenesis in the developing cerebral cortex and their immediate progeny. While one subset generates neurons directly, the other is largely non-neurogenic but also gives rise to Tbr2-positive basal precursors, thereby contributing indirectly to neurogenesis. Isolation of ; these distinct radial glia subtypes allowed determining interesting differences in their transcriptome. These transcriptomes were also strikingly different from the transcriptome of radial glia isolated at the end of neurogenesis. This analysis therefore identifies, for the first time, the lineage origin of basal progenitors and the molecular differences of this lineage in comparison to directly neurogenic and gliogenic radial glia. Experiment Overall Design: Comparison of radial glial subtypes
Project description:Evolution of the mammalian brain encompassed a remarkable increase in size of cerebral cortex, including tangential and radial expansion, but the mechanisms underlying these key parameters are still largely unknown. Here, we identified the novel DNA associated protein TRNP1 as a regulator of cerebral cortical expansion in both these dimensions. Gain and loss of function experiments in the mouse cerebral cortex in vivo demonstrate that high Trnp1 levels promote neural stem cell self-renewal and tangential expansion, while lower levels promote radial expansion resulting in a potent increase in the generation of intermediate progenitors and outer radial glial cells resulting in folding of the otherwise smooth murine cerebral cortex. Remarkably, TRNP1 expression levels exhibit regional differences also in the cerebral cortex of human fetuses anticipating radial or tangential expansion respectively. Thus, the dynamic regulation of TRNP1 is critical to regulate tangential and radial expansion of the cerebral cortex in mammals. We performed gene expression microarray analysis on embryonic mouse cerebral cortex derived from Trnp1 knockdown and control animals.
Project description:Since the discovery of radial glia as the source of neurons, their heterogeneity in regard to neurogenesis has been described by clonal and time-lapse analysis in vitro. However, the molecular determinants specifying neurogenic radial glia differently from radial glia that mostly self-renew remain ill-defined. Here, we isolated two radial glial subsets that co-exist at mid-neurogenesis in the developing cerebral cortex and their immediate progeny. While one subset generates neurons directly, the other is largely non-neurogenic but also gives rise to Tbr2-positive basal precursors, thereby contributing indirectly to neurogenesis. Isolation of these distinct radial glia subtypes allowed determining interesting differences in their transcriptome. These transcriptomes were also strikingly different from the transcriptome of radial glia isolated at the end of neurogenesis. This analysis therefore identifies, for the first time, the lineage origin of basal progenitors and the molecular differences of this lineage in comparison to directly neurogenic and gliogenic radial glia.
Project description:Evolution of the mammalian brain encompassed a remarkable increase in size of cerebral cortex, including tangential and radial expansion, but the mechanisms underlying these key parameters are still largely unknown. Here, we identified the novel DNA associated protein TRNP1 as a regulator of cerebral cortical expansion in both these dimensions. Gain and loss of function experiments in the mouse cerebral cortex in vivo demonstrate that high Trnp1 levels promote neural stem cell self-renewal and tangential expansion, while lower levels promote radial expansion resulting in a potent increase in the generation of intermediate progenitors and outer radial glial cells resulting in folding of the otherwise smooth murine cerebral cortex. Remarkably, TRNP1 expression levels exhibit regional differences also in the cerebral cortex of human fetuses anticipating radial or tangential expansion respectively. Thus, the dynamic regulation of TRNP1 is critical to regulate tangential and radial expansion of the cerebral cortex in mammals.
Project description:The goal of this study is to evaluate transcriptome profiles that accompany mouse radial glial cells and astrocytes isolated from the developing central nervous system. GLAST-positivity, a marker of radial glia and astrocyte lineage, was exploited to isolate cells from postnatal day 0 (P0) and P8 mouse brains using GLAST-specific antibodies conjugated to magnetic beads. mRNA from four separate biological replicates of GLAST-positive cells for each postnatal stage were used to construct cDNA libraries following TruSeq RNA sample preparation. Sequencing of libraries was conducted on Illumina HiSeq2000 using 100bp paired-end reads with 25 million reads per sample. Sequenced reads were aligned to the mouse genome (mm9) with the TopHat workflow and fragments per kilobase of transcript per million (FPKM) was calculated. Differential expression was determined using EdgeR with continuous dispersion and false discovery rate was calculated. RNA-seq data confirmed appropriate expression of 45 known housekeeping genes from different cell types in both P0 and P8 post-natal mouse brain. Differential expression of 1438 genes at P0 and 1100 at P8 GLAST-positive cells were found to have a fold change ≥2 and FDR <0.05. 18 genes were confirmed with qRT-PCR, demonstrating the validity of the RNA-seq method.
Project description:We report the transcriptomes of mouse E12.5 cortical radial glial cells and the changes caused by inhibition of the canonical BMP signalling effectors SMAD1/5, whose expression levels are reduced by 50% in the SmadNes mutants.