Project description:We sought to find molecular signatures of the SGZ cell types, and to characterize the molecular pathways and transcription factor cascades that define the neurogenic niche. We used laser capture microdissection and DNA microarrays to profile gene expression in the inner (SGZ) and outer portions of the dentate gyrus (DG). Since the vast majority of the cells in the DG are mature granule cells, we compared the expression of the inner and outer portions to reveal molecular markers for the less numerous populations of the SGZ. This data set is part of a larger study assessing conserved molecular signatures of neurogenesis in the hippocampal subgranular zone of rodents and primates. Using a combination of selective SGZ transcriptional profiling with laser microdissection and DNA microarrays as well as in situ hybridization (ISH), we developed an extensive molecular characterization of the mouse SGZ, identifying 367 genes enriched in the SGZ compared to mature granule neurons. These genes displayed a wide range of cellular expression patterns reflecting the cellular milieu of the SGZ, including progenitor and dividing cells, immature granule cells, astrocytes, oligodendrocytes, and GABAergic interneurons. We next used a comparable microarray data set in rhesus monkey that profiled the SGZ across postnatal development to identify genes related to developmentally regulated granule cell neurogenesis. The rhesus monkey SGZ showed highly significant similarity to mouse, whereas network analysis of these data identified SGZ-enriched gene sets with different temporal profiles reflecting differential time-courses for maturation of glia and granule neurons. One neurogenesis-related gene network showed a steady decrease in expression across postnatal rhesus development from birth to adulthood. This temporal pattern is highly correlated with the number of proliferating cells in the dentate gyrus, and the neurogenic transcription factors Sox4 and Sox11 are central hub genes for this gene network. A number of the genes in this network showed a similar postnatal downregulation in mouse, suggesting a general conservation of molecular mechanisms underlying developmental and adult neurogenesis in rodents and primates. Primate data available at: http://www.blueprintnhpatlas.org/ Brains from 10- to 11-week-old C57BL/6 male mice housed in three conditions (no running, 4 days of running, 30 days of running) were sectioned and the dentate gyrus was isolated. For each brain, the inner granule cell layer (containing the subgranular zone) and outer GCL were separated using laser capture microdissection, and RNA from each region was collected and processed as described in the protocols.

Project description:We sought to find molecular signatures of the SGZ cell types, and to characterize the molecular pathways and transcription factor cascades that define the neurogenic niche. We used laser capture microdissection and DNA microarrays to profile gene expression in the inner (SGZ) and outer portions of the dentate gyrus (DG). Since the vast majority of the cells in the DG are mature granule cells, we compared the expression of the inner and outer portions to reveal molecular markers for the less numerous populations of the SGZ. This data set is part of a larger study assessing conserved molecular signatures of neurogenesis in the hippocampal subgranular zone of rodents and primates. Using a combination of selective SGZ transcriptional profiling with laser microdissection and DNA microarrays as well as in situ hybridization (ISH), we developed an extensive molecular characterization of the mouse SGZ, identifying 367 genes enriched in the SGZ compared to mature granule neurons. These genes displayed a wide range of cellular expression patterns reflecting the cellular milieu of the SGZ, including progenitor and dividing cells, immature granule cells, astrocytes, oligodendrocytes, and GABAergic interneurons. We next used a comparable microarray data set in rhesus monkey that profiled the SGZ across postnatal development to identify genes related to developmentally regulated granule cell neurogenesis. The rhesus monkey SGZ showed highly significant similarity to mouse, whereas network analysis of these data identified SGZ-enriched gene sets with different temporal profiles reflecting differential time-courses for maturation of glia and granule neurons. One neurogenesis-related gene network showed a steady decrease in expression across postnatal rhesus development from birth to adulthood. This temporal pattern is highly correlated with the number of proliferating cells in the dentate gyrus, and the neurogenic transcription factors Sox4 and Sox11 are central hub genes for this gene network. A number of the genes in this network showed a similar postnatal downregulation in mouse, suggesting a general conservation of molecular mechanisms underlying developmental and adult neurogenesis in rodents and primates. Primate data available at: http://www.blueprintnhpatlas.org/

Project description:Adult radial glia-like cells (RGLs) residing in the subgranular zone (SGZ) of the dentate gyrus (DG) are finely regulated to control the generation of new neurons. Quiescence is essential for the long-term maintenance of the RGL pool. Intrinsic factors as well as extrinsic niche signals orchestrate the balance between RGL quiescence and activation, but the mechanisms are still not completely understood. Yap1, a core factor of Hippo signaling, is very important for the proliferation of stem cells of various organs and species, such as intestinal stem cells of the mouse and neural stem cells in Drosophila brain. Here I addressed the role of Yap1 in adult hippocampal neurogenesis by gain- and loss-of-function studies. I found that the expression of Yap1 was enriched in adult RGLs, but was undetectable in other cell types such as neurons and cells of the oligodendroglial lineage. Through the analysis of conditional knock-out of Yap1 in adult RGLs and their lineage, I found that fewer RGLs became activated while a significantly higher proportion of RGLs remained in the quiescent state. Conversely, overexpression of constitutively active mutant variant of Yap1 (Yap1 5SA) induced the proliferation of quiescent RGLs in vitro and in vivo. This effect was dependent on functional interaction with the TEA Domain Transcription Factor (TEAD). Pharmacological blocking the interaction between endogenous Yap1 and TEAD by verteporfin reduced the rate of proliferation of neural progenitors in vitro, which indicates a physiological role of Yap1-TEAD interaction in regulating the transition between quiescence and activation. Interestingly, constitutive expression of Yap1 5SA in RGLs blocked adult neurogenesis and retained the cells in a progenitor-like (Sox2+) state. To further explore the molecular mechanisms of Yap1 in regulating the activation of quiescent RGLs, single-cell RNA sequencing analysis was performed at 3 and 7 days following Yap1 5SA overexpression. Yap1 5SA overexpressing cells exhibited increased signature of active NSCs but also displayed distinct features such as epithelial-to-mesenchymal transition (EMT). Importantly, we found that Catenin Beta 1 (CTNNB1) was upregulated suggesting a potential involvement of Wnt signaling in the proliferative effect of Yap1 5SA overexpression in adult NSCs. In sum, this work provides compelling evidence for regulation of the balance between activation and quiescence of adult hippocampal RGLs by Yap1.

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The role of hippocampal niche exosomes in rat hippocampal neurogenesis after fimbria-fornix transection

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