Microglia transcriptome in a rat model of ischemic stroke
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ABSTRACT:
ORGANISM(S): Rattus norvegicus
PROVIDER: GSE148350 | GEO | 2020/04/24
REPOSITORIES: GEO
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Project description:Senescence-associated alterations in microglia may have profound impact on cerebral homeostasis and stroke outcomes. However, the lack of a transcriptome-wide comparison between young and aged microglia in the context of ischemia limits our understanding of aging-related mechanisms. Herein, we performed bulk RNA sequencing analysis of microglia purified from cerebral hemispheres of young adult (10-week-old) and aged (18-month-old) mice 5 days after distal middle cerebral artery occlusion or sham operation. Considerable transcriptional differences were observed between young and aged microglia in healthy brains, indicating heightened chronic inflammation in aged microglia. Following stroke, the overall transcriptional activation was more robust in young microglia than in aged microglia. Gene clusters with functional implications in immune inflammatory responses, immune cell chemotaxis, tissue remodeling, and cell-cell interactions were markedly activated in microglia of young but not aged stroke mice. These alterations in microglial gene response may contribute to aging-driven vulnerability and poorer recovery after ischemic stroke.
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Project description:Modulating M1/M2 polarization is a potential therapy for treating ischemic stroke. Repetitive transcranial magnetic stimulation (rTMS) held the capacity to regulate astrocytic polarization, but little is known about rTMS effects on microglia. Therefore, the present study aimed to investigate whether and how rTMS influence microglia polarization in ischemic stroke models. The 10-Hz rTMS was applied to transient middle cerebral artery occlusion (MCAO) rats and oxygen and glucose deprivation/ reoxygenation injured BV2 cells. Western blot, immunofluorescence and ELISA were used to detect M1/M2 markers. High-throughput sequencing, RT-PCR and FISH staining were adopted to test microRNA changes. The 10-Hz rTMS inhibited ischemia/reperfusion induced M1 microglia and significantly increased let-7b-5p. HMGA2 was proved to be the target protein of let-7b-5p and its downstream NF-κB signaling pathway were inhibited by rTMS. Microglia culture medium (MCM) collected from rTMS treated microglia had low TNF-α but high IL-10 concentration, leading to reduced neural death, minor ischemic volumes and improved functional recovery of MCAO animals. However, knockdown of let-7b-5p by antagomir reversed rTMS effects on microglia. In conclusion, high-frequency rTMS could improve functional recovery through inhibiting M1 microglia polarization via regulating let-7b-5p/HMGA2/NF-κB signaling pathway in cerebral ischemic stroke models.
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Project description:Microglial activation after stroke may lead to development of inflammation-induced brain damage. Here we uncover a ribosome-based mechanism/check point involved in control of the innate immune response and microglial activation orchestrated by RNA binding protein SRSF3. Using an in vivo model-system for analysis of the dynamic translational state of microglial ribosomes with mRNAs as input and newly synthesized peptides as an output, we found a marked dissociation of microglia mRNA and protein signatures following ischemic stroke. Highly up-regulated and ribosomes associated mRNAs were not translated 24hrs after stroke resulting in two distinct microglial molecular signatures, a highly specialized pro-inflammatory mRNA and immunomodulatory/homeostatic protein signatures. We found that this is due to specific translational suppression of highly expressed mRNAs through a 3'UTR-mediated mechanism involving the RNA binding protein SRSF3. This discovery suggests avenues for therapeutic modulation of innate immune response in resident microglia after stroke.
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