The mammalian central nervous system (CNS) contains a remarkable array of neural cells, each with a complex pattern of connections that together generate perceptions and higher brain functions. Here we describe a large-scale screen to create an atlas of CNS gene expression at the cellular level, and to provide a library of verified bacterial artificial chromosome (BAC) vectors and transgenic mouse lines that offer experimental access to CNS regions, cell classes and pathways. We illustrate the use of this atlas to derive novel insights into gene function in neural cells, and into principal steps of CNS development. The atlas, library of BAC vectors and BAC transgenic mice generated in this screen provide a rich resource that allows a broad array of investigations not previously available to the neuroscience community.

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Summary Comparative analysis of BACarray data can provide important insights into complex biological systems. As demonstrated in the accompanying paper, BACarray translational profiling permits comprehensive studies of translated mRNAs in genetically defined cell populations following physiological perturbations. To establish the generality of this approach, we present BACarray translational profiles for twenty four CNS cell populations, and identify known cell-specific and enriched transcripts for each population. We report thousands of cell-specific mRNAs that were not detected in whole tissue microarray studies, and provide examples that demonstrate the benefits deriving from comparative analysis. To provide a foundation for further biological and in silico studies, we provide a resource of sixteen transgenic mouse lines, their corresponding anatomic characterization, and BACarray translational profiles for cell types from a variety of CNS structures. This resource will enable a wide spectrum of molecular and mechanistic studies of both well known and previously uncharacterized neural cell populations.

In the above article, Figure 2A is stated to summarize data from Figures 1A and 1B; however, we inadvertently displayed a plot of a different data set that was collected with a similar but slightly different experimental design. The data in Figures 1A and 1B are from an experiment in which one group of flies underwent mock conditioning and an independent group was conditioned with electric shock, whereas the data in Figure 2A were from an experiment in which the same population of flies sequentially underwent mock conditioning and actual conditioning.We provide here a corrected graph for Figure 2A plotting the data from Figure 1. The new plot does not affect the description of the results in the paper or the conclusions drawn. We apologize for any inconvenience caused by this error.

Lurcher (Lc) is a gain-of-function mutation in the delta2 glutamate receptor (GRID2) that results in the cell-autonomous death of cerebellar Purkinje cells in heterozygous lurcher (+/Lc) mice. This in turn triggers the massive loss of afferent granule cells during the first few postnatal weeks. Evidence suggests that the death of Purkinje cells as a direct consequence of GRID2(Lc) activation and the secondary death of granule cells because of target deprivation occur by apoptosis. We have used mice carrying null mutations of both the Bax and p53 genes to examine the roles of these genes in cell loss in lurcher animals. The absence of Bax delayed Purkinje cell death in response to the GRID2(Lc) mutation and permanently rescued the secondary death of granule cells. In contrast, the p53 deletion had no effect on either cell death pathway. Our results demonstrate that target deprivation induces a Bax-dependent, p53-independent cell death response in cerebellar granule cells in vivo. In contrast, Bax plays a minor role in GRID2(Lc)-mediated Purkinje cell death.

Genetic analysis in mice has most commonly employed two general strategies: phenotypic screens for spontaneous or induced mutations and genotypic analysis using homologous recombination or gene trapping to produce deletion or insertion mutants. Here we use bacterial artificial chromosome (BAC)-mediated gene-dosage analysis in transgenic mice to reveal novel genetic functions that are not evident from conventional loss-of-function mutations. We demonstrate a role for the zinc-finger transcription factor Zipro1 (formerly Ru49 and Zfp38) in the proliferation of granule cell precursors in the developing cerebellum, and document the contribution of this process to the final stages of cerebellar morphogenesis. We also show that Zipro1 is expressed in skin, and increased Zipro1 dosage results in a hair-loss phenotype associated with increased epithelial cell proliferation and abnormal hair follicle development.

BackgroundHistone deacetylases (HDACs) are enzymes that modulate gene expression and cellular processes by deacetylating histones and non-histone proteins. While small molecule inhibitors of HDAC activity (HDACi) are used clinically in the treatment of cancer, pre-clinical treatment models suggest they also exert neuroprotective effects and stimulate neurogenesis in neuropathological conditions. However, the direct effects of HDACi on cell cycle progression and proliferation, two properties required for continued neurogenesis, have not been fully characterized in adult neural stem cells (NSCs). In this study, we examined the effects of two broad class I and class II HDACi on adult mouse NSCs, the hydroxamate-based HDACi suberoylanilide hydroxamic acid (vorinostat, SAHA) and the short chain fatty acid HDACi sodium butyrate.ResultsWe show that both HDACi suppress the formation of neurospheres by adult mouse NSCs grown in proliferation culture conditions in vitro. DNA synthesis is significantly inhibited in adult mouse NSCs exposed to either SAHA or sodium butyrate and inhibition is associated with an arrest in the G1 phase of the cell cycle. HDACi exposure also resulted in transcriptional changes in adult mouse NSCs. Cdk inhibitor genes p21 and p27 transcript levels are increased and associated with elevated H3K9 acetylation levels at proximal promoter regions of p21 and p27. mRNA levels for notch effector Hes genes and Spry-box stem cell transcription factors are downregulated, whereas pro-neural transcription factors Neurog1 and Neurod1 are upregulated. Lastly, we show HDAC inhibition under proliferation culture conditions leads to long-term changes in cell fate in adult mouse NSCs induced to differentiate in vitro.ConclusionSAHA and sodium butyrate directly regulate cdk inhibitor transcription to control cell cycle progression in adult mouse NSCs. HDAC inhibition results in G1 arrest in adult mouse NSCs and transcriptional changes associated with activation of neuronal lineage commitment programs and a reduction of stem/progenitor state. Changes in differentiated cell state in adult mouse NSCs treated with HDACi under proliferation culture conditions suggests an intrinsic relationship between multipotency, cell cycle progression and HDAC activity in these cells.

The basic helix-loop-helix (bHLH) transcription factors Ptf1a and Math1 are necessary for the specification of g-aminobutyric acid-ergic and glutamatergic cell lineages in the cerebellum, respectively. Recent evidence suggests cascades of bHLH factor activities drive cell type specificity in Ptf1a 1ve and Math1 1ve lineages. In this manuscript, we reveal cell lineages in the cerebellar cortex but not deep cerebellar nuclei express the pro-neural bHLH factor Neurogenin1 (Ngn1). Ngn1 is expressed in ventricular zone progenitors and in newly generated neurons in the caudal cerebellar primordium. In later embryonic and postnatal developmental stages, Ngn1 is expressed in progenitors and in migrating interneurons in the prospective white matter. Transgenic fate-mapping reveals Ngn1 reporter-gene expression in Purkinje cells, multiple inhibitory interneuron cell types, and in unipolar brush cells of the cortex. The data suggest Ngn1 is a component of the bHLH factor code regulating cell type specification in the cerebellar cortex. Developmental Dynamics 238:3310-3325,