Development of gene expression during astrocyte differentiation from human embryonic stem cells
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ABSTRACT: To identify genes that affect astrocyte differentiation from human embryonic stem cells, we have employed whole genome microarray expression profiling. We efficiently derived astrocytes through neural progenitor cells from human embryonic stem cells using our developed differentiation method. The cells on day 21 and 28 of astrocyte differentiation were compared with neural progenitor cells.
Project description:Chromosomes and genes are non-randomly arranged within the mammalian cell nucleus. Clustering of genes is of great significance in transcriptional regulation. However, the relevance of gene clustering in their expression during differentiation of neural precursor cells (NPCs) into astrocytes remains unclear. We performed a genome-wide enhanced circular chromosomal conformation capture (e4C) to screen genes associated with an astrocyte-specific gene, glial fibrillary acidic protein (Gfap), during astrocyte differentiation. We identified 13 genes that were specifically associated with Gfap and expressed in NPC-derived astrocytes. These results provide evidence for functional significance of gene clustering in transcriptional regulation during NPCs differentiation. comparison of NPCs vs LIF+ vs LIF- cells.
Project description:Heterogeneous astrocyte populations are defined by diversity in cellular environment, progenitor identity or function. Yet, little is known about the extent of the heterogeneity and how this diversity is acquired during development. We used SILAC and quantitative proteomics to characterise primary murine telencephalic progenitor cells from FOXG1 (forkhead box G1)-cre driven Tgfbr2 (transforming growth factor beta receptor 2) knockout mice and identified differential protein expression of the astrocyte proteins GFAP (glial fibrillary acidic protein) and MFGE8 (milk fat globule-EGF factor 8). Biochemical and histological investigations revealed distinct populations of astrocytes in the dorsal and ventral telencephalon marked by GFAP or MFGE8 protein expression. The two subtypes differed in their response to TGFβ-signalling. Impaired TGFβ-signalling affected numbers of GFAP-astrocytes in the ventral telencephalon. In contrast, TGFβ reduced MFGE8 expression in astrocytes deriving from both regions. Additionally, lineage tracing revealed that both GFAP and MFGE8 astrocyte subtypes derived partly from FOXG1-expressing neural precursor cells.
Project description:Astrocytes, the most abundant cells in the central nervous system, promote synapse formation and help refine neural connectivity. Although they are allocated to spatially distinct regional domains during development, it is unknown whether region-restricted astrocytes are functionally heterogeneous. Here we show that postnatal spinal cord astrocytes express several region-specific genes, and that ventral astrocyte-encoded Semaphorin3a (Sema3a) is required for proper motor neuron and sensory neuron circuit organization. Loss of astrocyte-encoded Sema3a led to dysregulated α−motor neuron axon initial segment orientation, markedly abnormal synaptic inputs, and selective death of α−but not of adjacent γ−motor neurons. Additionally, a subset of TrkA+ sensory afferents projected to ectopic ventral positions. These findings demonstrate that stable maintenance of a positional cue by developing astrocytes influences multiple aspects of sensorimotor circuit formation. More generally, they suggest that regional astrocyte heterogeneity may help to coordinate postnatal neural circuit refinement. 12 total samples consisting of three biological replicates each of flow sorted postnatal day 7 dorsal spinal cord astrocytes, ventral spinal cord astrocytes, dorsal SC non astrocytes, and ventral SC non astrocytes
Project description:Huntington’s Disease (HD) is a fatal, neurodegenerative disorder caused by a CAG repeat expansion, resulting in a mutant huntingtin protein. While it is now clear that astrocytes are affected by HD and significantly contribute to neuronal dysfunction and pathogenesis, the alterations in the transcriptional and epigenetic profiles in HD astrocytes have yet to be characterized. Here, we examined global transcription and chromatin accessibility dynamics during in vitro astrocyte differentiation in a transgenic non-human primate model of HD. We found global changed in accessibility and transcription across different stages of HD pluripotent stem cell differentiation, with distinct trends first observed in neural progenitor cells (NPCs), once cells have committed to a neural lineage. Transcription of p53 signaling and cell cycle pathway genes was highly impacted during differentiation, with depletion in HD NPCs and upregulation in HD astrocytes. E2F target genes also displayed this inverse expression pattern, and strong associations between E2F target gene expression and accessibility at nearby putative enhancers were observed. The results suggest that chromatin accessibility and transcription are altered throughout in vitro HD astrocyte differentiation and provide evidence that E2F dysregulation contributes to aberrant cell cycle reentry and apoptosis throughout the progression from NPCs to astrocytes.
Project description:Astrocytes within specific brain regions contribute uniquely to regional circuits for higher-order brain function through interactions with local neurons. The regional diversification of astrocytes is dictated by their embryonic origin, yet the mechanisms governing their regional allocation remain unknown. Here we show that allocation of astrocytes to specific brain regions requires the transcription factor 4 (Tcf4) mediated fate restriction during brain development. Loss of Tcf4 in ventral telencephalic neural progenitors alters the fate of oligodendrocyte precursors to transient intermediate astrocyte precursor cells, resulting in mislocated astrocytes in the dorsal neocortex. These ectopic astrocytes originated from the ventral telencephalon engage with neurons and acquire features reminiscent of local neocortical astrocytes. Furthermore, Tcf4 functions as a suppressor of astrocyte fate during differentiation of oligodendrocyte precursors, thereby restricting the fate to oligodendrocyte lineage. Our study reveals that fate restriction governs regional astrocyte allocation, contributing to astrocyte diversification across brain regions.
Project description:Chromosomes and genes are non-randomly arranged within the mammalian cell nucleus. Clustering of genes is of great significance in transcriptional regulation. However, the relevance of gene clustering in their expression during differentiation of neural precursor cells (NPCs) into astrocytes remains unclear. We performed a genome-wide enhanced circular chromosomal conformation capture (e4C) to screen genes associated with an astrocyte-specific gene, glial fibrillary acidic protein (Gfap), during astrocyte differentiation. We identified 13 genes that were specifically associated with Gfap and expressed in NPC-derived astrocytes. These results provide evidence for functional significance of gene clustering in transcriptional regulation during NPCs differentiation.
Project description:Astrocytes are one of the most abundant cell types in the mammalian central nervous system. Their diversity was widely investigated in the adult brain recently. However, the heterogeneity of astrocyte progenitors in their early developmental stage is still not clear. In this study, we dissected the subpopulations of neural progenitor cells at the neurogenesis and the early gliogenesis stages by single-cell RNA sequencing analysis. Interestingly, we identified two astrocyte progenitor subgroups from the cerebral cortex. The astrocyte subgroups highly express Sparc or Sparcl1, which were reported have contrary functions in astrocytes to regulate synapse formation. Further analysis for subpopulations of neural progenitors from the ventral forebrain also identified two astrocyte progenitor subgroups, showing similar gene expression patterns as in the cortex. Surprisingly, clustering analysis between the subpopulations from the dorsal and the ventral forebrains showed that the astrocyte progenitors expressing Sparc or Sparcl1 were clustered together, irrespective of their derived regions. These results showed an early divergence of astrocyte progenitors and their cross-regional conservation at the start of gliogenesis during brain development.
Project description:The glial environment determines the outcome of neurological disease progression, yet much of our knowledge still relies on preclinical animal studies, especially regarding astrocyte heterogeneity. In murine models of traumatic brain injury, beneficial functions of proliferating reactive astrocytes on disease outcome have been unraveled, but little is known if and when they are present in human brain pathology. Here, we examined a broad spectrum of pathologies with and without intracerebral hemorrhage and found a striking correlation between lesions involving blood-brain barrier rupture and astrocyte proliferation that was further corroborated in an assay probing for neural stem cell potential. Most importantly, proteomic analysis unraveled a crucial signaling pathway regulating this astrocyte plasticity with GALECTIN3 as a novel marker for proliferating astrocytes and the GALECTIN3-binding protein LGALS3BP as a functional hub mediating astrocyte proliferation and neurosphere formation. Taken together, this work identifies a therapeutically relevant astrocyte response and their molecular regulators in different pathologies affecting the human cerebral cortex.
Project description:We have showed that cancer cells (or tumorigenic cells) resemble neural stem/progenitor cells in regulatory network, tumorigenicity and differentiation potential. We have shown PRMT1 is a protein that is upreguated in and promotes vaious cancers. The expression of its gene is localized to embryonic neural cells during vertebrate embryogenesis. The project is to identify the interaction partners of PRMT1, by which PRMT1 regulates neural stemness in both cancer cells and neural stem cells.