Project description:Astrocytes and neurons coexist and interact in the CNS1,2. Given that many signaling and pathological events are protein-driven, identifying astrocyte and neuron proteomes is essential for elucidating the complex protein networks that dictate their respective contributions to physiology and disease. Here, we used cell- and subcompartment-specific proximity-dependent biotinylation3 to study the proteomes of striatal astrocytes and medium spiny neurons (MSNs) in vivo. We evaluated cytosolic and plasma membrane compartments for astrocytes and MSNs, revealing how these cells differ at the protein level and in their core signaling machinery. We assessed subcellular compartments of astrocytes including end feet and processes to reveal the molecular basis of essential astrocyte signaling and homeostatic functions. Unexpectedly, SAPAP3 proteins (gene; Dlgap3) associated with obsessive compulsive disorder (OCD) and repetitive behaviors4-11 were detected at equivalent levels in striatal astrocyte and MSN plasma membrane and cytosolic compartments. Astrocytic expression was confirmed by RNA-seq, fluorescence in situ hybridization and immunohistochemistry. Furthermore, genetic rescue experiments combined with behavioral analyses and proteomics in a mouse model4 of OCD lacking SAPAP3 revealed contributions of SAPAP3 in astrocytes and MSNs to repetitive and anxiety-related OCD behaviors. Our data define how astrocytes and neurons differ at the protein level and in their major signaling pathways, how astrocyte proteomes vary between physiological subcompartments, and how specific astrocyte and neuronal molecular mechanisms contribute to a psychiatric disease. Targeting both astrocytes and neurons together is likely to be therapeutically effective in complex CNS disorders.
Project description:In vivo chemogenetic activation of astrocytes in the striatum via an engineered Gi-protein-coupled receptor was conducted in wild-type and SAPAP3 KO OCD mice. The resultant striatal tissue was extracted, homogenized in a detergent-free buffer, digested, and analyzed with LC/MS-MS.
Project description:We investigated the sub-proteomes of different functional compartments in astrocyte and neurons in the striatum. We compared the proteomes to the cell-specific RNA profiles of neurons and astrocytes from these analyses. We found one gene and protein that was highly expressed in neurons and astrocytes called SAPAP3. Knockout of this gene product results in an OCD-like phenotype in mouse. RNA-seq of astrocytes and bulk RNA-seq analyses of this mouse model revealed very low DEGs.
Project description:Astrogliosis is a hallmark of the response to brain ischemia, comprised of changes in gene expression and morphology. Hsp72 protects from cerebral ischemia, and although several mechanisms of protection have been investigated, effects on astrocyte activation are unknown. To identify potential mechanisms of protection, gene expression was assessed in mice subjected to middle cerebral artery (MCAO) or sham surgery, of either wildtype (WT) or Hsp72-overexpressing (Hsp72Tg) mice. After stroke, both genotypes exhibited genes related to cell death, stress response, and immune response. Furthermore, genes indicative of astrocyte activation, including cytoskeletal proteins and cytokines, were upregulated. To measure astrocyte activation after stroke, detailed histological and morphological analyses were performed in the cortical penumbra after stroke using unbiased stereology. Consistent with other reports, we observed a marked and persistent increase in glial fibrillary acidic protein (GFAP ) as soon as 3 hours after MCAO. In contrast, vimentin immunoreactivity appeared 12-24 hours after stroke, peaked at 72 hours, and returned to baseline after 30 days. Surprisingly, no change in overall astrocyte number was observed based on glutamine synthetase (GS) immunoreactivity. To determine if Hsp72Tg mice exhibited altered astrocyte activation compared to WT controls, morphological evaluation by fractal analysis was used. Overexpression of Hsp72 reduced astrocyte cell area, arbor area, and to a lesser extent fractal dimension, 72 hours following stroke. In conclusion, in vivo overexpression of Hsp72 alters gene expression following stroke, including genes involved in astrocyte activation, and decreases astrocyte activation acutely following MCAO. Thus, modulation of astrogliosis may be a neuroprotective mechanism exerted by Hsp72 after ischemia. A total of 10 samples were analyzed, with 5 of each genotype, wildtype (WT) and Hsp72-overexpressing (Hsp72Tg) mice. Of the 5 in each group, 3 received middle cerebral artery occlusion (MCAO) and 2 received a sham surgery. The sham samples serve as the controls for the MCAO samples in each genotype. All samples were taken from the ischemic or control hemisphere 24 hours after surgery.
Project description:Astrocytes differentiate into a spectrum of neurotoxic and neuroprotective reactive subpopulations after CNS injury and in disease. In astrocyte conditional ADCY10 (sAC) knockout mice, reactive astrocytes exhibit a shift towards neurotoxic phenotypes implicating sAC as a critical regulator of neuroprotective astrocyte differentiation.
Project description:Chromosomes and genes are non-randomly arranged within the mammalian cell nucleus. Clustering of genes is of great significance in transcriptional regulation. However, the relevance of gene clustering in their expression during differentiation of neural precursor cells (NPCs) into astrocytes remains unclear. We performed a genome-wide enhanced circular chromosomal conformation capture (e4C) to screen genes associated with an astrocyte-specific gene, glial fibrillary acidic protein (Gfap), during astrocyte differentiation. We identified 13 genes that were specifically associated with Gfap and expressed in NPC-derived astrocytes. These results provide evidence for functional significance of gene clustering in transcriptional regulation during NPCs differentiation. comparison of NPCs vs LIF+ vs LIF- cells.
Project description:CHMP2B mutant astrocytes revealed an accumulation of autophagosomes, which trigger the observed astrocyte reactivity leading to increased cytokine release, altered mitochondria dynamics and metabolic changes.
Project description:Astrogliosis is a hallmark of the response to brain ischemia, comprised of changes in gene expression and morphology. Hsp72 protects from cerebral ischemia, and although several mechanisms of protection have been investigated, effects on astrocyte activation are unknown. To identify potential mechanisms of protection, gene expression was assessed in mice subjected to middle cerebral artery (MCAO) or sham surgery, of either wildtype (WT) or Hsp72-overexpressing (Hsp72Tg) mice. After stroke, both genotypes exhibited genes related to cell death, stress response, and immune response. Furthermore, genes indicative of astrocyte activation, including cytoskeletal proteins and cytokines, were upregulated. To measure astrocyte activation after stroke, detailed histological and morphological analyses were performed in the cortical penumbra after stroke using unbiased stereology. Consistent with other reports, we observed a marked and persistent increase in glial fibrillary acidic protein (GFAP ) as soon as 3 hours after MCAO. In contrast, vimentin immunoreactivity appeared 12-24 hours after stroke, peaked at 72 hours, and returned to baseline after 30 days. Surprisingly, no change in overall astrocyte number was observed based on glutamine synthetase (GS) immunoreactivity. To determine if Hsp72Tg mice exhibited altered astrocyte activation compared to WT controls, morphological evaluation by fractal analysis was used. Overexpression of Hsp72 reduced astrocyte cell area, arbor area, and to a lesser extent fractal dimension, 72 hours following stroke. In conclusion, in vivo overexpression of Hsp72 alters gene expression following stroke, including genes involved in astrocyte activation, and decreases astrocyte activation acutely following MCAO. Thus, modulation of astrogliosis may be a neuroprotective mechanism exerted by Hsp72 after ischemia.