Glia最新文献

Chromatin remodeling complexes (CRCs) participate in oligodendrocyte (OL) differentiation, survival, and maintenance. We asked whether CRCs also control the proliferation of OL precursors (OPs)-focusing on the INO80 complex, which is known to regulate the proliferation of a variety of other cell types during development and disease. CRISPR/Cas9-mediated inactivation of Ino80 in vitro, or Cre-mediated deletion in vivo, slowed the OP cell cycle substantially by prolonging G1. RNAseq analysis revealed that E2F target genes were dysregulated in OPs from INO80-deficient mice, but correlated RNAseq and ATAC-seq uncovered no general correlation between gene expression and altered nucleosome positioning at transcription start sites. Fluorescence photobleaching experiments in cultured OPs demonstrated that histone H2A.Z mobility increased following the loss of INO80, suggesting that INO80 regulates the cell cycle machinery in OPs through H2A.Z/H2A exchange. We also present evidence that INO80 associates with OLIG2, a master regulator of OL development.

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease, characterized by memory decline and behavioral changes. Its pathological features include senile plaques, neurofibrillary tangles, and reactive gliosis, comprising abnormal accumulations of β-amyloid peptide (Aβ) and hyperphosphorylated tau protein surrounded by reactive astrocytes and microglia. Recently, it has emerged that severe reactive astrocytes and MAOB-dependent production of GABA and H₂O₂ are the real causes of learning and memory impairment and neurodegeneration. Diverse mouse models for AD have been developed to clarify pathological mechanisms and discover therapeutic strategies and drugs. However, there are many shortfalls and discrepancies among them. A new AD mouse model named FAD^4T has been developed to overcome various shortcomings. Here, we employed astrocyte-focused screening procedures to examine the pathological features of FAD^4T as an AD model. Our results revealed that the FAD^4T mice showed abnormal accumulation of Aβ plaques in overall brain regions at 6 and 12 months. We found astrocytic hypertrophy with a significant elevation of GFAP and LCN2. However, the expressions of MAOB and iNOS, a severe reactive astrocyte marker, were unchanged. Electrophysiological and behavioral analysis indicated aberrant tonic GABA release, reduced neuronal activity, and impaired CA1-specific memory. These findings demonstrate that FAD^4T mice mimic pathological and functional features of AD, different from other AD mouse models. These findings demonstrate that FAD^4T mimics some features of AD patients but lacks other important features, such as severe reactive astrocytes and neurodegeneration. This astrocyte-focused screening method offers valuable tools for advancing AD research and developing new therapeutic strategies.

The function of microglia during progression of Alzheimer's disease (AD) can be investigated using mouse models that enable genetic manipulation of microglial subpopulations in a temporal manner. We developed mouse lines that express either Cre recombinase (Cre) for constitutive targeting, or destabilized-domain Cre recombinase (DD-Cre) for inducible targeting from the Cst7 locus (Cst7^DD-Cre) to specifically manipulate disease associated microglia (DAM) and crossed with Ai14 tdTomato cre-reporter line mice. Cst7^Cre was found to target all brain resident myeloid cells, due to transient developmental expression of Cst7, but no expression was found in the inducible Cst7^DD-Cre mice. Further crossing of this line with 5xFAD mice combined with dietary administration of trimethoprim to induce DD-Cre activity produces long-term labeling in DAM without evidence of leakiness, with tdTomato-expression restricted to cells surrounding plaques. Using this model, we found that DAMs are a subset of plaque-associated microglia (PAMs) and their transition to DAM increases with age and disease stage. Spatial transcriptomic analysis revealed that tdTomato+ cells show higher expression of disease and inflammatory genes compared to other microglial populations, including non-labeled PAMs. These models allow either complete cre-loxP targeting of all brain myeloid cells (Cst7^Cre), or inducible targeting of DAMs, without leakiness (Cst7^DD-Cre).

Vincent Soubannier^{1 2}, Mathilde Chaineau^{1 2}, Eric Deneault ^{1 2 4}, Lale Gursu^{1 2}, Sarah Lépine^{1 2}, David Kalaydjian^{1 2}, Julien Sirois^{1 2}, Ghazal Haghi^{1 2}, Guy Rouleau¹, Thomas M Durcan^{1 2 3}, Stefano Stifani¹

4- New address: Centre for Oncology, Radiopharmaceuticals and Research (CORR), Biologic and Radiopharmaceuticals Drugs Directorate (BRDD), Health Products and Food Branch (HPFD), Health Canada, Ottawa, ON K1A 0K9, Canada

An error in the author list led to the omission of Dr. Eric Deneault who helped generate the isogenic iPSCs used in this study. To correct this oversight, he is now included as an author in the corrected manuscript.

We apologize for this error.

The Fragile X Messenger Ribonucleoprotein (FMRP) is an RNA binding protein that regulates the translation of multiple mRNAs and is expressed by neurons and glia in the mammalian brain. Loss of FMRP leads to fragile X syndrome (FXS), a common inherited form of intellectual disability and autism. While most research has been focusing on the neuronal contribution to FXS pathophysiology, the role of glia, particularly oligodendrocytes, is largely unknown. FXS individuals are characterized by white matter changes, which imply impairments in oligodendrocyte differentiation and myelination. We hypothesized that FMRP regulates oligodendrocyte maturation and myelination during postnatal development. Using a combination of human pluripotent stem cell-derived oligodendrocytes and an Fmr1 knockout rat model, we studied the role of FMRP on mammalian oligodendrocyte development. We found that the loss of FMRP leads to shared defects in oligodendrocyte morphology in both rat and human systems in vitro, which persist in the presence of FMRP-expressing axons in chimeric engraftment models. Our findings point to species-conserved, cell-autonomous defects during oligodendrocyte maturation in FXS.

The myelination is a critical process during brain development. This study aimed to explore the impact of volatile anesthetic sevoflurane on developing myelination and the role of microglial activation in this process. Neonatal C57BL/6J mice were exposed to sevoflurane at their postnatal 6-8 days. Neurobehavioral tests were used to assess fine motor and cognitive functions. Myelination of hippocampus (HC) and corpus callosum (CC), as well as microglial activation, were determined by western blotting and immunostaining. Lipid droplets were assessed by Oil-Red-O and Bodipy staining. Further, primary microglia were co-cultured with oligodendrocyte precursor cell (OPC) to determine the role of microglia in the proliferation and differentiation of OPC. And microglial inhibitor minocycline and CSF1R inhibitor PLX5622 were administered to assess the effects of microglial activation on developing myelination. The results showed that repeated sevoflurane exposure impaired both fine motor and cognitive functions and induced abnormal expressions of myelin-related proteins myelin basic protein (MBP) and platelet-derived growth factor α receptor (PDGFR-α). And accumulations of lipid droplets were found in the microglia of HC and CC after sevoflurane exposure. Further, the spatiotemporal response to repeated sevoflurane exposure in glial cells exhibited an aberrant myelination process and microglial polarization. The conditioned medium from sevoflurane-treated microglia inhibited the OPC proliferation and differentiation, while minocycline or PLX5622 alleviated sevoflurane-induced neuroinflammation and hypomyelination. Therefore, repeated sevoflurane exposure negatively affected OPC differentiation and myelination trajectory through hyperactivating microglia in developing brain, leading to motor and cognitive impairments, while microglial inhibition/depletion could protect against sevoflurane-induced damage on developing myelination.

Inflammation-induced oligodendrocyte death and CNS demyelination are key features of multiple sclerosis (MS). Inflammation-triggered endoplasmic reticulum (ER) stress and oxidative stress promote tissue damage in MS and in its preclinical animal model, experimental autoimmune encephalitis (EAE). Compound AA147 is a potent activator of the ATF6 signaling arm of the unfolded protein response (UPR) that can also induce antioxidant signaling through activation of the NRF2 pathway in neuronal cells. Previous work showed that AA147 protects multiple tissues against ischemia/reperfusion damage through ATF6 and/or NRF2 activation; however, its therapeutic potential in neuroinflammatory disorders remains unexplored. Here, we demonstrate that AA147 ameliorated the clinical symptoms of EAE and reduced ER stress, oligodendrocyte loss, and demyelination. Additionally, AA147 suppressed T cells in the CNS without altering the peripheral immune response. Importantly, AA147 significantly increased the expressions of Grp78, an ATF6 target gene, in oligodendrocytes, while enhancing levels of Grp78 as well as Ho-1, an NRF2 target gene, in microglia. In cultured oligodendrocytes, AA147 promoted nuclear translocation of ATF6, but not NRF2. Intriguingly, AA147 altered the microglia activation profile, possibly by triggering the NRF2 pathway. AA147 was not therapeutically beneficial during the acute EAE stage in mice lacking ATF6 in oligodendrocytes, indicating that protection primarily involves ATF6 activation in these cells. Overall, our results suggest AA147 as a potential therapeutic opportunity for MS by promoting oligodendrocyte survival and regulating microglia status through distinct mechanisms.

Ibudilast, an inhibitor of macrophage migration inhibitory factor (MIF) and phosphodiesterase (PDE), has been recently shown to have neuroprotective effects in a variety of neurologic diseases. We utilize a chick excitotoxic retinal damage model to investigate ibudilast's potential to protect retinal neurons. Using single cell RNA-sequencing (scRNA-seq), we find that MIF, putative MIF receptors CD74 and CD44, and several PDEs are upregulated in different retinal cells during damage. Intravitreal ibudilast is well tolerated in the eye and causes no evidence of toxicity. Ibudilast effectively protects neurons in the inner nuclear layer from NMDA-induced cell death, restores retinal layer thickness on spectral domain optical coherence tomography (SD-OCT), and preserves retinal neuron function, particularly for the ON bipolar cells, as assessed by electroretinography. PDE inhibition seems essential for ibudilast's neuroprotection, as AV1013, the analogue that lacks PDE inhibitor activity, is ineffective. scRNA-seq analysis reveals upregulation of multiple signaling pathways, including mTOR, in damaged Müller glia (MG) with ibudilast treatment compared to AV1013. Components of mTORC1 and mTORC2 are upregulated in both bipolar cells and MG with ibudilast. The mTOR inhibitor rapamycin blocked accumulation of pS6 but did not reduce TUNEL positive dying cells. Additionally, through ligand-receptor interaction analysis, crosstalk between bipolar cells and MG may be important for neuroprotection. We have identified several paracrine signaling pathways that are known to contribute to cell survival and neuroprotection and might play essential roles in ibudilast function. These findings highlight ibudilast's potential to protect inner retinal neurons during damage and show promise for future clinical translation.

Parkinson's disease (PD) is characterized by the degeneration of dopaminergic nigrostriatal inputs, which causes striatal network dysfunction and leads to pronounced motor deficits. Recent evidence highlights astrocytes as a potential local source for striatal neuromodulation. There is substantial evidence for norepinephrine-mediated recruitment of cortical astrocyte activity during movement and locomotion. However, it is unclear how astrocytes in the striatum, a region devoid of norepinephrine neuromodulatory inputs, respond during locomotion. Moreover, it remains unknown how dopamine loss affects striatal astrocyte activity and whether astrocyte activity regulates behavioral deficits in PD. We addressed these questions by performing astrocyte-specific calcium recordings and manipulations using in vivo fiber photometry and chemogenetics. We find that locomotion elicits astrocyte calcium activity over a slower timescale than neurons. Acute pharmacological blockade of dopamine receptors only moderately reduced locomotion-related astrocyte activity. Yet, unilateral dopamine depletion significantly attenuated astrocyte calcium responses. Chemogenetic stimulation of G_i-coupled receptors partially improved this functional astrocyte deficit in dopamine-lesioned mice. In parallel, chemogenetic manipulation restored asymmetrical motor deficits and moderately improved open-field exploratory behavior. Together, our results establish a novel role for functional striatal astrocyte signaling in modulating motor function in PD and highlight non-neuronal targets for potential PD therapeutics.