Project description:To investigate the functional heterogeneity of astrocytes from a defined brain region, we designed 14 experimental manipulations including Huntington's disease models, pathological challenges, ionic and GPCR signaling alterations, and analyzed the transcriptomic profiles of striatal astrocytes. From the analyses, we have identified context-specific changes of striatal astrocytes.
Project description:To investigate the functional heterogeneity of astrocytes from a defined brain region, we designed 12 experimental manipulations including Huntington's disease models, pathological challenges, ionic and GPCR signaling alterations, and analyzed the transcriptomic profiles of striatal astrocytes. From the analyses, we have identified context-specific changes of striatal astrocytes.
Project description:To investigate the functional heterogeneity of astrocytes from a defined brain region, we performed single cell RNA-seq of striatal cells from adult mice (8-9 weeks old). From the analyses, we have identified context-specific changes of striatal astrocytes.
Project description:Astrocytes tile the central nervous system and are widely implicated in brain diseases, but the molecular mechanisms by which astrocytes contribute to brain disorders remain incompletely explored. By performing astrocyte gene expression analyses following 14 experimental perturbations of relevance to the striatum, we discovered that striatal astrocytes mount context-specific molecular responses at the level of genes, pathways, and upstream regulators. Through data mining, we also identified astrocyte pathways in Huntington's disease (HD) that were reciprocally altered with respect to the activation of striatal astrocyte G protein-coupled receptor (GPCR) signaling. Furthermore, selective striatal astrocyte stimulation of the Gi-GPCR pathway in vivo corrected several HD-associated astrocytic, synaptic, and behavioral phenotypes, with accompanying improvement of HD-associated astrocyte signaling pathways, including those related to synaptogenesis and neuroimmune functions. Overall, our data show that astrocytes are malleable, using context-specific responses that can be dissected molecularly and used for phenotypic benefit in brain disorders.
Project description:Protoplasmic astrocytes in layers II to VI of the mammalian neocortex have historically been thought to comprise a homogeneous population. Given that layer-specific neuronal subtypes play essential roles in cortical circuitry, astrocytes might also be expected to support and modify this circuitry in a layer-specific manner. In order to investigate whether protoplasmic astrocytes exhibit layer-specific heterogeneity, we compared the gene expression profiles of astrocytes between upper layers (layers II to IV) and deep layers (layers V and VI). Although most genes known to be preferentially expressed in astrocytes (astrocyte-enriched genes) were equally expressed between upper-layer astrocytes and deep-layer astrocytes, some such genes (astrocyte-enriched genes or genes with known function in astrocytes) were significantly enriched in upper-layer astrocytes or deep-layer astrocytes.
Project description:Astrocyte heterogeneity is an increasingly prominent research topic, and studies in the brain have demonstrated substantial variation in astrocyte form and function, both between and within regions. In contrast, retinal astrocytes are not well understood and remain incompletely characterized. Along with optic nerve astrocytes, they are responsible for supporting retinal ganglion cell axons and an improved understanding of their role is required. We have used a combination of microdissection and Ribotag immunoprecipitation to isolate ribosome-associated mRNA from retinal astrocytes and investigate their transcriptome, which we also compared to astrocyte populations in the optic nerve. Astrocytes from these regions are transcriptionally distinct, and we identified retina-specific astrocyte genes and pathways. Moreover, although they share much of the ‘classical’ gene expression patterns of astrocytes, we uncovered unexpected variation, including in genes related to core astrocyte functions. We additionally identified the transcription factor Pax8 as a highly specific marker of retinal astrocytes and demonstrated that these astrocytes populate not only the retinal surface, but also the prelaminar region at the optic nerve head. These findings are likely to contribute to a revised understanding of the role of astrocytes in the retina.