Project description:Homeobox gene Tlx3 is known to promote glutamatergic differentiation and is expressed in post-mitotic neurons of CNS. Contrary to this here, we discovered that Tlx3 is expressed in the proliferating progenitors of the external granule layer in the cerebellum, and examined factors that regulate this expression. Using Pax6-/-Sey mouse model and molecular interaction studies we demonstrate Pax6 is a key activator of Tlx3 specifically in cerebellum, and induces its expression starting at embryonic day (E)15. By Postnatal day (PN)7, Tlx3 is expressed in a highly restricted manner in the cerebellar granule neurons of the posterior cerebellar lobes, where it is required for the restricted expression of nicotinic cholinergic receptor-α3 subunit (Chrnα3) and other genes involved in formation of synaptic connections and neuronal migration. These results demonstrate a novel role for Tlx3 and indicate that Pax6-Tlx3 expression and interaction is part of a region specific regulatory network in cerebellum and its deregulation during development could possibly lead to Autistic spectral disorders (ASD) Anterior and posterior lobes of PN7 mouse cerebellum were isolated separately and differentially expressed genes were identified.
Project description:Homeobox gene Tlx3 is known to promote glutamatergic differentiation and is expressed in post-mitotic neurons of CNS. Contrary to this here, we discovered that Tlx3 is expressed in the proliferating progenitors of the external granule layer in the cerebellum, and examined factors that regulate this expression. Using Pax6-/-Sey mouse model and molecular interaction studies we demonstrate Pax6 is a key activator of Tlx3 specifically in cerebellum, and induces its expression starting at embryonic day (E)15. By Postnatal day (PN)7, Tlx3 is expressed in a highly restricted manner in the cerebellar granule neurons of the posterior cerebellar lobes, where it is required for the restricted expression of nicotinic cholinergic receptor-α3 subunit (Chrnα3) and other genes involved in formation of synaptic connections and neuronal migration. These results demonstrate a novel role for Tlx3 and indicate that Pax6-Tlx3 expression and interaction is part of a region specific regulatory network in cerebellum and its deregulation during development could possibly lead to Autistic spectral disorders (ASD)
Project description:Origins of the brain tumor, medulloblastoma, from stem cells or restricted pro-genitor cells are unclear. To investigate this, we activated oncogenic Hedgehog signaling in multipotent and lineage-restricted CNS progenitors. We observed that normal unipo-tent cerebellar granule neuron precursors (CGNP) derive from hGFAP+ and Olig2+ rhombic lip progenitors. Hedgehog activation in a spectrum of early and late stage CNS progenitors generated similar medulloblastomas, but not other brain cancers, indicating that acquisition of CGNP identity is essential for tumorigenesis. We show in human and mouse medulloblastoma that cells expressing the glia-associated markers Gfap and Olig2 are neoplastic and that they retain features of embryonic-type granule lineage progenitors. Thus, oncogenic Hedgehog signaling promotes medulloblastoma from lineage-restricted granule cell progenitors. Gene expression profiling of cerebellar tumors generated from various early and late stage CNS progenitor cells. Experiment Overall Design: Group comparisons with biological replicates
Project description:Control of neuronal precursor cell proliferation is essential for normal brain development, and deregulation of this fundamental developmental event contributes to brain diseases. Typically, neuronal precursor cell proliferation extends over long periods of time during brain development. However, how neuronal precursor proliferation is regulated in a temporally specific manner remains to be elucidated. Here, we report that conditional knockout of the transcriptional regulator SnoN in cerebellar granule neuron precursors robustly inhibits the proliferation of these cells and promotes their cell cycle exit at later stages of cerebellar development in the postnatal mouse brain. In laser capture microdissection followed by RNASeq, designed to profile gene expression specifically in the external granule layer (EGL) of the cerebellum, we find that SnoN promotes the expression of cell proliferation genes and concomitantly represses differentiation genes in granule neuron precursors in vivo. Remarkably, bioinformatics analyses reveal that SnoN-regulated genes contain binding sites for the transcription factors N-myc and Pax6, which promote the proliferation and differentiation of granule neuron precursors, respectively. Accordingly, we uncover novel physical interactions of SnoN with N-myc and Pax6 in cells. In behavior analyses, conditional knockout of SnoN impairs cerebellar-dependent learning in a delayed eye-blink conditioning paradigm, suggesting that SnoN-regulation of granule neuron precursor proliferation bears functional consequences at the organismal level. Our findings define a novel function and mechanism for the major transcriptional regulator SnoN in the control of granule neuron precursor proliferation in the mammalian brain.
Project description:Control of neuronal precursor cell proliferation is essential for normal brain development, and deregulation of this fundamental developmental event contributes to brain diseases. Typically, neuronal precursor cell proliferation extends over long periods of time during brain development. However, how neuronal precursor proliferation is regulated in a temporally specific manner remains to be elucidated. Here, we report that conditional knockout of the transcriptional regulator SnoN in cerebellar granule neuron precursors robustly inhibits the proliferation of these cells and promotes their cell cycle exit at later stages of cerebellar development in the postnatal mouse brain. In laser capture microdissection followed by RNASeq, designed to profile gene expression specifically in the external granule layer (EGL) of the cerebellum, we find that SnoN promotes the expression of cell proliferation genes and concomitantly represses differentiation genes in granule neuron precursors in vivo. Remarkably, bioinformatics analyses reveal that SnoN-regulated genes contain binding sites for the transcription factors N-myc and Pax6, which promote the proliferation and differentiation of granule neuron precursors, respectively. Accordingly, we uncover novel physical interactions of SnoN with N-myc and Pax6 in cells. In behavior analyses, conditional knockout of SnoN impairs cerebellar-dependent learning in a delayed eye-blink conditioning paradigm, suggesting that SnoN-regulation of granule neuron precursor proliferation bears functional consequences at the organismal level. Our findings define a novel function and mechanism for the major transcriptional regulator SnoN in the control of granule neuron precursor proliferation in the mammalian brain.
Project description:Origins of the brain tumor, medulloblastoma, from stem cells or restricted pro-genitor cells are unclear. To investigate this, we activated oncogenic Hedgehog signaling in multipotent and lineage-restricted CNS progenitors. We observed that normal unipo-tent cerebellar granule neuron precursors (CGNP) derive from hGFAP+ and Olig2+ rhombic lip progenitors. Hedgehog activation in a spectrum of early and late stage CNS progenitors generated similar medulloblastomas, but not other brain cancers, indicating that acquisition of CGNP identity is essential for tumorigenesis. We show in human and mouse medulloblastoma that cells expressing the glia-associated markers Gfap and Olig2 are neoplastic and that they retain features of embryonic-type granule lineage progenitors. Thus, oncogenic Hedgehog signaling promotes medulloblastoma from lineage-restricted granule cell progenitors. Gene expression profiling of cerebellar tumors generated from various early and late stage CNS progenitor cells.
Project description:Mutations in the gene encoding the chromatin remodeler CHD8 are a highly penetrant risk factor for autism spectrum disorder (ASD). Although cerebellar abnormalities have been involved in ASD pathogenesis, the underlying mechanisms of CHD8 in the regulation of cerebellar function has remained unknown, however. Here we show that the cerebellar granule neurons–specific deletion of Chd8 manifests reduced proliferation and differentiation of granule neuron progenitors, leading to cerebellar hypoplasia and motor coordination defects in mice. CHD8 was found to regulate the expression of neuronal genes and to be required for maturation of cerebellar granule neurons. Furthermore, we found that CHD8 is preferentially bound to promoter regions and is necessary for modulation of local chromatin accessibilities at promoter regions of active gene. Our results thus uncover a critical role for CHD8 in cerebellar development and have important implications for understanding the cerebellar contributions to ASD pathogenesis.
Project description:Cerebellar circuitry is critical for balance and motor control among a wide array of functions and largely consists of granule and Purkinje neurons. Bergmann glia in the cerebellum form distinct morphological structures that facilitate granule neuron migration during development and that maintain the cerebellar organization and functional integrity. At present, molecular control of the formation and morphogenesis of Bergmann glia remains obscure. In this study, we found that Zeb2 (a.k.a. Sip1 or Zfhx1b), a Mowat-Wilson syndrome-associated transcriptional regulator, is highly restricted to Bergmann glia and is essential for their development and maturation. The mice with Zeb2 ablation in the cerebellar neural progenitor exhibit dysgenesis of cerebellar cortical lamination and locomotion defects. Deletion of Zeb2 markedly reduced Bergmann glial proliferation, differentiation and the establishment of the normal radial scaffold, disrupting migration of granule cell progenitors from external to internal granular layers. Transcriptome profiling indicated that Zeb2 regulates multiple pathways including FGF and Notch signaling as well as axonal guidance cues including Netrin G2 and Gdf10 to control Bergmann glial development. Our data reveal that Zeb2 acts as a transcriptional integrator of diverse signaling pathways to regulate the formation and morphogenesis of Bergmann glia ensuring maintenance of cerebellar integrity, suggesting that Zeb2 dysfunction in Bergmann glia might contribute to motor deficits in Mowat-Wilson syndrome.