Project description:Abnormalities in neocortical and synaptic development have been associated with neurodevelopmental disorders. However, the molecular and cellular mechanisms regulating the formation of the initial synapses in an evolutionary advanced neocortical layer, the subplate (SP), are poorly understood. Our snRNAseq screen of human prefrontal neocortices from early (11/12 PCW), mid (14/15 PCW) to late (17/18 PCW) fetal developmental stages revealed the bipartite-to-tripartite differentiation of SP neuronal subclasses. Using polysome profiling with RNAseq, we report for the first time a set of mRNAs undergoing translational control in cellular subclasses of developing human prefrontal neocortices, including SP neurons. By examining both mouse and human neocortex, we further found that an autism spectrum disorder (ASD)-risk gene and RNA binding protein CUGBP Elav-Like Family Member 4 (CELF4) is selectively expressed in the neurons of two synapse-enriched compartments, the SP and the marginal zone. Furthermore, CELF4 binds mRNA targets that are encoded by the synaptic genes associated with ASD and adverse neurodevelopmental outcomes; albeit in an evolutionarily advanced fashion between mouse and human synaptic mRNAs. The selective forebrain Celf4 deletion from developing mouse cortical neurons disrupts the balance of SP synapses in a gender-specific fashion. Taken together, our results underscore the importance of RNA binding proteins and mRNA translation in evolutionarily advanced synaptic development, as well as their possible contribution to gender specific protein synthesis and vulnerability.
Project description:Abnormalities in neocortical and synaptic development have been associated with neurodevelopmental disorders. However, the molecular and cellular mechanisms regulating the formation of the initial synapses in an evolutionary advanced neocortical layer, the subplate (SP), are poorly understood. Our snRNAseq screen of human prefrontal neocortices from early (11/12 PCW), mid (14/15 PCW) to late (17/18 PCW) fetal developmental stages revealed the bipartite-to-tripartite differentiation of SP neuronal subclasses. Using polysome profiling with RNAseq, we report for the first time a set of mRNAs undergoing translational control in cellular subclasses of developing human prefrontal neocortices, including SP neurons. By examining both mouse and human neocortex, we further found that an autism spectrum disorder (ASD)-risk gene and RNA binding protein CUGBP Elav-Like Family Member 4 (CELF4) is selectively expressed in the neurons of two synapse-enriched compartments, the SP and the marginal zone. Furthermore, CELF4 binds mRNA targets that are encoded by the synaptic genes associated with ASD and adverse neurodevelopmental outcomes; albeit in an evolutionarily advanced fashion between mouse and human synaptic mRNAs. The selective forebrain Celf4 deletion from developing mouse cortical neurons disrupts the balance of SP synapses in a gender-specific fashion. Taken together, our results underscore the importance of RNA binding proteins and mRNA translation in evolutionarily advanced synaptic development, as well as their possible contribution to gender specific protein synthesis and vulnerability.
Project description:It has been shown that in mammalian cells alternative transcription initiation is extensively regulated during development and across cell-types, which confers dynamic transcript 5âUTR repertoire. However it is underexplored how the heterogeneity of 5âUTR isoforms would affect the downstream steps for protein expression, such as translation. To this end, we globally compared the translational profile of distinct mRNA TSS isoforms in mouse fibroblast cells, by combining deep-sequencing based mRNA 5âends profiling and polysome fractionation. We demonstrated the extensive translation regulation conferred by TSS heterogeneity. 5'end sequencing in seven polysome fractions, in two replicates, using Illumina Hiseq2000
Project description:We followed the polysomal association of maternal and early zygotic transcriptome over the first few hours of embryonic development, prior to and after MBT. We isolated polysome-associated (bound) and non-polysome-associated (unbound) mRNAs using sucrose gradient centrifugation followed by size fractionation. Using next generation sequencing (RNA-seq), we profiled the transcriptome in polysome-bound and unbound fractions. Our analysis revealed distinct dynamics of polysome association of cytoplasmically polyadenylated maternal mRNAs.
Project description:Cerebral organoids â three-dimensional cultures of human cerebral tissue derived from pluripotent stem cells â have emerged as models of human cortical development. However, the extent to which in vitro organoid systems recapitulate neural progenitor cell proliferation and neuronal differentiation programs observed in vivo remains unclear. Here we use single-cell RNA sequencing (scRNA-seq) to dissect and compare cell composition and progenitor-to-neuron lineage relationships in human cerebral organoids and fetal neocortex. Covariation network analysis using the fetal neocortex data reveals known and novel interactions among genes central to neural progenitor proliferation and neuronal differentiation. In the organoid, we detect diverse progenitors and differentiated cell types of neuronal and mesenchymal lineages, and identify cells that derived from regions resembling the fetal neocortex. We find that these organoid cortical cells use gene expression programs remarkably similar to those of the fetal tissue in order to organize into cerebral cortex-like regions. Our comparison of in vivo and in vitro cortical single cell transcriptomes illuminates the genetic features underlying human cortical development that can be studied in organoid cultures. 734 single-cell transcriptomes from human fetal neocortex or human cerebral organoids from multiple time points were analyzed in this study. All single cell samples were processed on the microfluidic Fluidigm C1 platform and contain 92 external RNA spike-ins. Fetal neocortex data were generated at 12 weeks post conception (chip 1: 81 cells; chip 2: 83 cells) and 13 weeks post conception (62 cells). Cerebral organoid data were generated from dissociated whole organoids derived from induced pluripotent stem cell line 409B2 (iPSC 409B2) at 33 days (40 cells), 35 days (68 cells), 37 days (71 cells), 41 days (74 cells), and 65 days (80 cells) after the start of embryoid body culture. Cerebral organoid data were also generated from microdissected cortical-like regions from H9 embryonic stem cell derived organoids at 53 days (region 1, 48 cells; region 2, 48 cells) or from iPSC 409B2 organoids at 58 days (region 3, 43 cells; region 4, 36 cells).
Project description:Cerebral organoids – three-dimensional cultures of human cerebral tissue derived from pluripotent stem cells – have emerged as models of human cortical development. However, the extent to which in vitro organoid systems recapitulate neural progenitor cell proliferation and neuronal differentiation programs observed in vivo remains unclear. Here we use single-cell RNA sequencing (scRNA-seq) to dissect and compare cell composition and progenitor-to-neuron lineage relationships in human cerebral organoids and fetal neocortex. Covariation network analysis using the fetal neocortex data reveals known and novel interactions among genes central to neural progenitor proliferation and neuronal differentiation. In the organoid, we detect diverse progenitors and differentiated cell types of neuronal and mesenchymal lineages, and identify cells that derived from regions resembling the fetal neocortex. We find that these organoid cortical cells use gene expression programs remarkably similar to those of the fetal tissue in order to organize into cerebral cortex-like regions. Our comparison of in vivo and in vitro cortical single cell transcriptomes illuminates the genetic features underlying human cortical development that can be studied in organoid cultures.