Project description:Dendrite and synapse development are critical for establishing appropriate neuronal circuits, and disrupted timing of these events can alter connectivity leading to disordered neural function. In early postnatal development of cerebellar granule neurons (CGNs), the expression of many genes is temporally regulated. Further, NFI (Nuclear Factor I) proteins have been shown to play important roles in the regulation of gene expression in developing CGNs. To identify NFI-regulated genome-wide targets involved in late maturation of mouse CGNs, we performed two groups of microarray expression analysis: (1) temporal expression arrays using 1.5 and 6 day cultures of mouse CGNs representing immature and more mature CGNs, respectively, which identified 844 Temporal-Up or Down genes; and (2) NFI-regulated genes in 6 day CGN cultures that were infected at the time of plating with lentiviral vectors expressing either NFI dominant repressor (NFI-EnR) or EnR control protein. This identified 686 NFI-Up (NFI-EnR down-regulated) or NFI-Down (NFI-EnR up-regulated) genes. Overlap analysis identified 212 temporal genes that were regulated by NFI. These results indicated that NFI plays a pivotal role in the regulation of late CGN maturation.
Project description:Dendrite and synapse development are critical for establishing appropriate neuronal circuits, and disrupted timing of these events can alter connectivity leading to disordered neural function. In early postnatal development of cerebellar granule neurons (CGNs), the expression of many genes is temporally regulated. Further, NFI (Nuclear Factor I) proteins have been shown to play important roles in the regulation of gene expression in developing CGNs. To identify NFI-regulated genome-wide targets involved in late maturation of mouse CGNs, we performed two groups of microarray expression analysis: (1) temporal expression arrays using 1.5 and 6 day cultures of mouse CGNs representing immature and more mature CGNs, respectively, which identified 844 Temporal-Up or Down genes; and (2) NFI-regulated genes in 6 day CGN cultures that were infected at the time of plating with lentiviral vectors expressing either NFI dominant repressor (NFI-EnR) or EnR control protein. This identified 686 NFI-Up (NFI-EnR down-regulated) or NFI-Down (NFI-EnR up-regulated) genes. Overlap analysis identified 212 temporal genes that were regulated by NFI. These results indicated that NFI plays a pivotal role in the regulation of late CGN maturation. For temporal arrays, mouse CGN progenitors were purified from P6 mouse cerebellum and cultured for either 1.5 or 6 days. Three biological replicates were analyzed for each time point. For NFI arrays, CGN progenitors from P6 mice were transduced upon plating with either NFI-EnR or EnR control lentivirus and cultured 6 days. Four pairs of biological replicates were performed.
Project description:Swiss-Webster B mouse postnatal day 4-5 primary cerebellar culture (pooled from litter mates) treated with sonic hedgehog (Shh), controls (veh), growth arrested (arrest), cycloheximide (cyc) for 1, 3 and 24 hours. Different treatment conditions with biological replicates. Mouse cerebellar granule cell neuron precursors under different treatment conditions.
Project description:It is generally believed that cerebellar granule neurons originate exclusively from granule neuron precursors (GNPs) in the external germinal layer (EGL). Here we identify a rare population of neuronal progenitors in the developing cerebellum that expresses Nestin. Although Nestin is widely considered a marker for multipotent stem cells, these Nestin-expressing progenitors (NEPs) are committed to the granule neuron lineage. Unlike conventional GNPs, which reside in the outer EGL and proliferate extensively, NEPs reside in the deep part of the EGL and are quiescent. Expression profiling reveals that NEPs are distinct from GNPs, and in particular, express markedly reduced levels of genes associated with DNA repair. Consistent with this, upon aberrant activation of Sonic hedgehog (Shh) signaling, NEPs exhibit more severe genomic instability and give rise to tumors more efficiently than GNPs. These studies identify a novel progenitor for cerebellar granule neurons and a novel cell of origin for medulloblastoma. 4 samples of Nestin expressing progenitors (NEPs), 4 samples of Math1 positive cells (GNPs) and 3 samples of Neural stem cells (CD133+ NSCs) were used for microarray analysis to determine the distinct genetic profile of NEPs. 4 samples of NEP-derived tumor and 4 samples of GNP-derived tumor were used to determine the similarity of those tumors by microarray analysis.
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.