Project description:The biological basis of male-female brain differences has been difficult to elucidate in humans. The most striking morphological difference is size, with males having on average a larger brain than females; yet a mechanistic understanding of how this difference arises remains to be elucidated. Here, we use brain organoids to demonstrate that while sex chromosomal complement has no observable effect on neurogenesis, sex steroids, namely androgens, lead to increased proliferation of cortical progenitors and an increased neurogenic pool. Transcriptomic analysis and functional studies demonstrate downstream effects on HDAC activity and mTOR pathway. Finally, we show that androgens specifically increase neurogenic output of excitatory neuronal progenitors, while inhibitory neuronal progenitors are not increased. These findings uncover a hitherto unknown role for androgens in regulating excitatory neuron number and represent a first step towards understanding the origin of human sex-related brain differences.
Project description:A complex train of events unfolds during brain development, guided by activation/repression of gene expression programs. It remains unclear how this process is disrupted in disease. Here we integrate human genetics with transcriptomic data from differentiation of human embryonic stem cells into cortical excitatory neurons. This reveals a cascade of transcriptional programs activated during early corticoneurogenesis in vitro and in vivo. Genetic variation in these programs is robustly associated with neuropsychiatric disorders and cognitive function, with variants concentrated in loss-of-function intolerant genes. Neurogenic programs also capture schizophrenia GWAS enrichment previously identified in mature excitatory neurons, suggesting that pathways activated during pre-natal development underlie disease-relevant deficits in mature neuronal function. Down-regulation of these programs in DLG2-/- lines delays expression of cell-type identity and impairs neuronal migration, morphology and action potential generation, validating predicted deficits. These data implicate specific cellular pathways underlying neurodevelopment in the aetiology of multiple neuropsychiatric disorders and cognition.
Project description:The proper balance of excitatory and inhibitory neurons is crucial to normal processing of somatosensory information in the dorsal spinal cord. Two neural basic helix-loop-helix transcription factors, Ascl1 and Ptf1a, are essential for generating the correct number and sub-type of neurons in multiple regions of the nervous system. M-BM- In the dorsal spinal cord, Ascl1 and Ptf1a have contrasting functions in specifying inhibitory versus excitatory neurons. To understand how Ascl1 and Ptf1a function in these processes, we identified their direct transcriptional targets genome-wide in the embryonic mouse neural tube using ChIP-Seq and RNA-Seq. We show that Ascl1 and Ptf1a regulate the specification of excitatory and inhibitory neurons in the dorsal spinal cord through direct regulation of distinct homeodomain transcription factors known for their function in neuronal sub-type specification. Besides their roles in regulating these homeodomain factors, Ascl1 and Ptf1a each function differently during neuronal development with Ascl1 directly regulating genes with roles in several steps of the neurogenic program including, Notch signaling, neuronal differentiation, axon guidance, and synapse formation. In contrast, Ptf1a directly regulates genes encoding components of the neurotransmitter machinery in inhibitory neurons, and other later aspects of neural development distinct from those regulated by Ascl1. Moreover, Ptf1a represses the excitatory neuronal fate by directly repressing several targets of Ascl1. Examination of the Ascl1 and Ptf1a bound sequences shows they are enriched for a common E-Box with a GC core and with additional motifs used by Sox, Rfx, Pou, and Homeodomain factors. Ptf1a bound sequences are uniquely enriched in an E-Box with a GA/TC core and in the binding motif for its co-factor Rbpj, providing two keys to specificity of Ptf1a binding. The direct transcriptional targets identified for Ascl1 and Ptf1a provide a molecular understanding for how they function in neuronal development, particularly as key regulators of homeodomain transcription factors required for neuronal sub-type specification. Examination of gene expression in Ascl1 and Ptf1a lineage cells in the developing neural tube.
Project description:The proper balance of excitatory and inhibitory neurons is crucial to normal processing of somatosensory information in the dorsal spinal cord. Two neural basic helix-loop-helix transcription factors, Ascl1 and Ptf1a, are essential for generating the correct number and sub-type of neurons in multiple regions of the nervous system. M-BM- In the dorsal spinal cord, Ascl1 and Ptf1a have contrasting functions in specifying inhibitory versus excitatory neurons. To understand how Ascl1 and Ptf1a function in these processes, we identified their direct transcriptional targets genome-wide in the embryonic mouse neural tube using ChIP-Seq and RNA-Seq. We show that Ascl1 and Ptf1a regulate the specification of excitatory and inhibitory neurons in the dorsal spinal cord through direct regulation of distinct homeodomain transcription factors known for their function in neuronal sub-type specification. Besides their roles in regulating these homeodomain factors, Ascl1 and Ptf1a each function differently during neuronal development with Ascl1 directly regulating genes with roles in several steps of the neurogenic program including, Notch signaling, neuronal differentiation, axon guidance, and synapse formation. In contrast, Ptf1a directly regulates genes encoding components of the neurotransmitter machinery in inhibitory neurons, and other later aspects of neural development distinct from those regulated by Ascl1. Moreover, Ptf1a represses the excitatory neuronal fate by directly repressing several targets of Ascl1. Examination of the Ascl1 and Ptf1a bound sequences shows they are enriched for a common E-Box with a GC core and with additional motifs used by Sox, Rfx, Pou, and Homeodomain factors. Ptf1a bound sequences are uniquely enriched in an E-Box with a GA/TC core and in the binding motif for its co-factor Rbpj, providing two keys to specificity of Ptf1a binding. The direct transcriptional targets identified for Ascl1 and Ptf1a provide a molecular understanding for how they function in neuronal development, particularly as key regulators of homeodomain transcription factors required for neuronal sub-type specification. Examination of Ascl1 and Ptf1a genome-wide binding in developing neural tube.
Project description:Müller glial cells (MG) generate retinal progenitor (RPC)-like cells after injury in non-mammalian species, though this does not occur in the mammalian retina. Studies have profiled gene expression in these cells to define genes that may be relevant to their differences in neurogenic potential. However, less is known about differences in micro-RNA (miRNA) expression. In this study, we compared miRNAs from RPCs and MG to identify miRNAs more highly expressed in RPCs, and others more highly expressed in MG. To determine whether these miRNAs are relevant to the difference in neurogenic potential between these two cell types, we tested them in dissociated cultures of MG using either mimics or antagomiRs to increase or reduce expression, respectively. Among the miRNAs tested, miR-25 and miR-124 over-expression, or let-7 antagonism, induced Ascl1 expression and conversion of approximately 40% of mature MG into a neuronal/RPC phenotype. Our results suggest that the differences in miRNA expression between MG and RPCs contribute to their difference in neurogenic potential and that manipulations in miRNAs provide a new tool to reprogram MG for retinal regeneration.
Project description:The hormonal milieu influences immune tolerance as well as the immune response against viruses and cancer, but the direct effect of androgens on cellular immunity remains largely uncharacterized. We therefore sought to evaluate the effect of androgens on murine CD4 T-cells by micro-array analysis
Project description:Human neural organoid models have become an important tool for studying neurobiology. In this work, we compared Matrigel to an N-cadherin peptide-functionalized gelatin methacryloyl hydrogel (termed GelMA-Cad) for culturing cortical neural organoids. Specifically, we compare five materials: (1) Matrigel, (2) GelMA-Cad with high crosslinker (HC), (3) GelMA-Cad with low crosslinker (LC), (4) GelMA HC and (5) GelMA LC. We determined that both mechanical properties and peptide presentation can tune cell fate and diversity in gelatin-based matrices during differentiation. Of particular note, cortical organoids cultured in GelMA-Cad produce higher numbers of neurogenic and ciliated radial glia and upper-layer excitatory neurons—an important population for modeling neurodegenerative disease—compared to GelMA and Matrigel controls.
Project description:The hormonal milieu influences immune tolerance as well as the immune response against viruses and cancer, but the direct effect of androgens on cellular immunity remains largely uncharacterized. We therefore sought to evaluate the effect of androgens on murine CD4 T-cells by micro-array analysis Male mice were castrated, or received sham surgery. Four weeks later, CD4 cells were sorted by FACS. Splenocytes were pooled from 3 mice to be analysed on each micro-array chip. 2 micro-array chips were used for each group (containing samples from 6 mice total for each group)
Project description:Glial cells have been proposed as an endogenous source of progenitors for the treatment of neural deficits. However, the cellular and molecular mechanisms underpinning the neurogenic potential of certain populations of adult glial cells, are not known. Using single cell transcriptomic profiling, we show here that enteric glial cells represent a cell state attained by autonomic neural crest cells as they transition during development along a linear default differentiation trajectory that allows them to retain neurogenic potential while acquiring a gene expression profile associated with their role in neuronal support and immunomodulation. Key neurogenic loci in early enteric nervous system progenitors remain in open chromatin configuration in mature enteric glia, thus facilitating neuronal differentiation under appropriate conditions. Molecular profiling and gene targeting of enteric glial cells in a novel cell culture system of enteric neurogenesis and a gut injury model, demonstrated that neuronal differentiation of glia is driven by transcriptional programs employed in vivo by early progenitors. Our work provides mechanistic insight into the dynamic regulatory landscape underpinning the development of intestinal neural circuits and generates a platform for advancing glial cells as therapeutic agents for the treatment of neural deficits.