Project description:<p>We sought to characterize cellular heterogeneity in the human cerebral cortex at a molecular level during cortical neurogenesis. We captured single cells and generated sequencing libraries using the C1TM Single-Cell Auto Prep System (Fluidigm), the SMARTer Ultra Low RNA Kit (Clontech), and the Nextera XT DNA Sample Preparation Kit (Illumina). We performed unbiased clustering of the single cells and further examined transcriptional variation among cell groups interpreted as radial glia. Within this population, the major sources of variation related to cell cycle progression and the stem cell niche from which radial glia were captured. We found that outer subventricular zone radial glia (oRG cells) preferentially express genes related to extracellular matrix formation, migration, and stemness, including <i>TNC</i>, <i>PTPRZ1</i>, <i>FAM107A</i>, <i>HOPX</i>, and <i>LIFR</i> and related this transcriptional state to the position, morphology, and cell behaviors previously used to classify the cell type. Our results suggest that oRG cells maintain the subventricular niche through local production of growth factors, potentiation of growth factor signals by extracellular matrix proteins, and activation of self-renewal pathways, thereby contributing to the developmental and evolutionary expansion of the human neocortex.</p> <p>For <b>study version 2</b>, we have updated this data set to include additional primary cells that we infer to represent microglia, endothelial cells, and immature astrocytes, as well as additional cells from the developing neural retina, and from iPS-cell derived cerebral organoids. The genes distinguishing these cell populations may reveal biological processes supporting the diverse functions of these cell types as well as vulnerabilities of specific cell types in human genetic diseases and in viral infections.</p> <p>For <b>study version 3</b>, we have updated the data set to include additional primary cells, including those published in Nowakowski, et al., Science 2017: "Spatiotemporal Gene Expression Trajectories Reveal Developmental Hierarchies of the Human Cortex" (<i>in press</i>)</p>
Project description:The loss-of-function mutations in the chromatin remodeler CHD8, a high-risk factor in autism spectrum disorder (ASD), lead to severe developmental delay, however, the underlying mechanisms remains elusive. Here, we use transcriptome and genomic occupancy reveal that CHD8 regulates chromatin accessibility and activates neurogenesis-related genes for cortical neurogenesis.
Project description:According to the protocortex hypothesis, extrinsic thalamic signaling is necessary for refining cortical areas and cell types, but the mechanism by which these inputs shape human cortex development remains largely unexplored. We fuse cortical and thalamic organoids to study this process. Using single-nuclei RNA-sequencing and cellular imaging, we discover that thalamic signals during a progenitor-rich critical period drive developmental gene expression changes and shift cell fate toward increased excitatory neurogenesis. We find NRXN1 mediates thalamic axon contact with primate-enriched outer radial glia; genetic perturbation of NRXN1 reduces these contacts and significantly attenuates upper-layer neurogenesis. These findings underscore the influence of thalamic input on human cortical radial glia specification, and suggest a novel mechanism for thalamic regulation of human outer radial glia cell fate.
Project description:Neurogenesis, a critical process implicated in diverse brain disorders, is greatly diminished in the adult human brain, complicating direct investigations into its mechanistic role in disease. In the olfactory epithelium (OE), olfactory sensory neurons (OSNs) maintain homeostasis via continual neurogenesis throughout life, providing a niche to investigate neurogenesis in vivo. However, the molecular mechanisms underlying this process and its similarities to brain neurogenesis remain largely unknown. Here, we performed single-nucleus RNA-seq (snRNA-seq from the human OE of 6 living adult donors, yielding 145,720 high-quality transcriptomics. Integrating with an independent OE dataset from 4 adults, different developmental stages of OSNs were identified, including neural precursor cells (globose basal cells, GBCs), as well as immature and mature OSNs. We inferred trajectories and assessed the transcriptional and regulatory dynamics of OSN development. Genes and transcription factors involved in regulating neuronal differentiation and neurogenesis were highly expressed in GBCs and early immature OSNs, but were downregulated in mature neurons. OSNs and cortical excitatory neurons exhibited convergence during early developmental stages, including dynamically expressed genes, biological processes, transcription factors, as well as polygenic enrichment for psychiatric disorders. In addition, highly matched expression dynamics of autism risk genes between OSNs and cortical excitatory neurons further validated their convergence. Overall, OSNs cells in the olfactory neuroepithelium represent a potential proxy to study gene programs involved in neurogenesis in the human brain, providing an accessible model for investigating neurodevelopmental dysfunction in psychiatric disorders.
Project description:Although neurogenesis in the adult brain recapitulates processes that occur during embryonic development, adult neurogenesis exhibits distinct characteristics from its embryonic counterpart. However, the intrinsic mechanism underlying the differential regulation of neurogenesis between these two stages remains unclear. Herein, we show that the ablation of RNA-binding protein HuR in neural stem cells (NSCs) impairs adult, but not embryonic, neurogenesis. HuR is predominantly expressed in the cytoplasm of embryonic NSCs but translocates into the nucleus of adult NSCs. Transcriptomic analysis of HuR-deficient adult NSCs revealed that nuclear HuR primarily regulates alternative splicing of numerous premRNA transcripts, including focal adhesion kinase (FAK). HuR-deficient adult NSCs generate increased FAK mRNA isoforms with shorter 5’ UTRs, leading to enhanced FAK mRNA translation and hyperactivated FAK signaling, and inhibition of FAK ameliorates defective adult neurogenesis and impaired hippocampus-dependent learning in HuR-deficient mice. Taken together, these findings reveal novel mechanistic insights into the differential regulation of embryonic and adult neurogenesis through developmental cytoplasmic-to-nuclear translocation of HuR in NSCs.
Project description:Non-coding regions compose most of the human genome, yet their functionality is poorly defined. In the developing human neocortex, non-coding regulatory elements tightly regulate expression to direct neural progenitor proliferation and neurogenesis. Here, we define thousands of non-coding elements involved in human neurogenesis by contrasting chromatin accessibility via ATAC-seq from the germinal zone and cortical plate.