Project description:Neural stem cell regulation is essential for the formation of the central nervous system and homeostatic neurogenesis in the adult mammalian brain. The RNAseIII Drosha, a key component of the miRNA microprocessor, plays a central role in regulating NSC maintenance partially through a miRNA-independent mechanism. Drosha controls mRNA expression levels by targeting and cleaving evolutionary conserved stem-loop hairpins located in the mRNAs of stem cell-related transcription factors. However, it is unknown how the Drosha-mediated endonucleolytic cleavage of mRNA is regulated. Here, we identify novel Drosha and NFIB interactors in hippocampal NSCs by in vitro pull-down assays followed by Mass Spectrometry. We unravel the RNA binding proteins implicated in Drosha-mediated regulation of neurogenesis and we find Scaffold Attachment Factor B1 to play a novel and essential role in NFIB mRNA regulation during neural stem cell differentiation.
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:Muscle Stem Cells or satellite cells (SCs) are required for muscle regeneration. In resting muscles, SCs are kept in quiescence. After injury, SCs undergo rapid activation, proliferation and differentiation to repair damaged muscles. The transcriptome alteration during SC activation is well characterized. While transcriptome is not exactly represent proteome because of post-transcriptional regulations such as miRNA induced gene silencing. However, little is known about SC proteome. We obtained in vivo activated SCs (ASCs) from 3 days post injured muscles for high resolution mass spectrometry Bruker timsTOF Pro. Compared with QSC proteome,, we identified the pathways that are differentially expressed between them.
Project description:In acute myeloid leukemia (AML), leukemia stem cells (LSC) play a central role in disease progression and recurrence due to their intrinsic capacity for self-renewal and chemotherapy resistance. Whereas epigenetic mechanisms balance normal blood stem cell self-renewal and fate decisions, mutation and dysregulation of epigenetic regulators are considered fundamental to leukemia initiation and progression. Alterations in miRNA function represent a non-canonical epigenetic mechanism influencing malignant hematopoiesis, however the function of miRNA in human LSC remains undetermined. Here we show that miRNA profiling of fractionated AML populations defines an LSC-specific signature that is highly prognostic for patient survival. Gain- and loss-of-function analyses demonstrated that miR-126 restrained cell cycle progression, prevented differentiation, and increased self-renewal of human LSC. By targeting the G0 to G1 gatekeeper CDK3, miR-126 preserved LSC quiescence and promoted chemotherapy resistance. Thus, in AML, miRNAs influence patient outcome through post-transcriptional regulation of stemness programs in LSC.
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes
Project description:The activation of quiescent neural stem cells (qNSCs) in the dentate gyrus is required for lifelong neurogenesis. However, the mechanisms that promote the exit of neural stem cells (NSCs) from quiescence remain elusive. We demonstrate that the expression of plant homeodomain finger protein 2 (Phf2) activates the exit of postnatal mouse NSC from shallow quiescence. Loss of Phf2 prevents NSC activation and neurogenesis in postnatal 30 (P30) mice but does not decrease the label-retaining NSC pool, indicating that Phf2 is not required for the exit of NSC from quiescence. NSC-specific deletion of Phf2 modestly compromises embryonic mouse NSC proliferation without increasing apoptosis, indicating that Phf2 is crucial for embryonic development. Moreover, human cortical organoids reveal that Phf2 promotes NPC proliferation via a lysine demethylase-independent manner. Mechanistically, Phf2 directly binds to the cohesion complex via Rad21 and regulates the DNA replication in mouse NSC by associating with the cohesion complex releasing protein Wapl activity. Our study identifies the Phf2-cohesin complex mediated DNA replication for neural stem cell activation in a lysine demethylase-independent manner.
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes Sequence library of miRNAs from a single sample of human foetal mesenchymal stem cells. Results tested and confirmed by northern blotting. Please note that only raw data files are available for the embryonic and neual samples and thus, directly submitted to SRA (SRX547311, SRX548700, respectively under SRP042115/PRJNA247767)