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Three-dimensional Confocal Analysis of Microglia/macrophage Markers of Polarization in Experimental Brain Injury
Published on: September 4, 2013
Circular RNA PTP4A2 regulates microglial polarization through STAT3 to promote neuroinflammation in ischemic stroke
Xingzhi Wang1,2,3, Shenyang Zhang1,2, Bingchen Lv1,2
1Department of Neurology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
Objective:
Microglial polarization plays a critical role in neuroinflammation and may be a potential therapeutic target for ischemic stroke. This study was to explore the role and underlying molecular mechanism of Circular RNA PTP4A2 (circPTP4A2) in microglial polarization after ischemic stroke.
Methods:
C57BL/6J mice underwent transient middle cerebral artery occlusion (tMCAO), while primary mouse microglia and BV2 microglial cells experienced oxygen glucose deprivation/reperfusion (OGD/R) to mimic ischemic conditions. CircPTP4A2 shRNA lentivirus and Colivelin were used to knock down circPTP4A2 and upregulate signal transducer and activator of transcription 3 (STAT3) phosphorylation, respectively. Microglial polarization was assessed using immunofluorescence staining and Western blot. RNA pull-down and RNA binding protein immunoprecipitation (RIP) were applied to detect the binding between circPTP4A2 and STAT3.
Results:
The levels of circPTP4A2 were significantly increased in plasma and peri-infarct cortex in tMCAO mice. CircPTP4A2 knockdown reduced infarct volume, increased cortical cerebral blood flow (CBF), and attenuated neurological deficits. It also decreased pro-inflammatory factors levels in peri-infarct cortex and plasma, and increased anti-inflammatory factors concentrations 24 h post-stroke. In addition, circPTP4A2 knockdown suppressed M1 microglial polarization and promoted M2 microglial polarization in both tMCAO mice and OGD/R-induced BV2 microglial cells. Moreover, circPTP4A2 knockdown inhibited the phosphorylation of STAT3 induced by oxygen-glucose deprivation. In contrast, increased phosphorylation of STAT3 partly counteracted the effects of circPTP4A2 knockdown. RNA pull-down and RIP assays further certified the binding between circPTP4A2 and STAT3.
Conclusion:
These results revealed regulatory mechanisms of circPTP4A2 that stimulated neuroinflammation by driving STAT3-dependent microglial polarization in ischemic brain injury. CircPTP4A2 knockdown reduced cerebral ischemic injury and promoted microglial M2 polarization, which could be a novel therapeutic target for ischemic stroke.
Insights
Circular RNA PTP4A2 (circPTP4A2) drives neuroinflammation in ischemic stroke by promoting M1 microglial polarization via STAT3. Knocking down circPTP4A2 reduces brain injury and promotes beneficial M2 polarization, offering a potential therapeutic target.
Area of Science:
- Neuroscience
- Molecular Biology
- Immunology
Background:
- Microglial polarization is crucial in neuroinflammation and a potential therapeutic target for ischemic stroke.
- Circular RNAs (circRNAs) are increasingly recognized for their roles in various biological processes, including disease pathogenesis.
Purpose of the Study:
- To investigate the role of Circular RNA PTP4A2 (circPTP4A2) in microglial polarization following ischemic stroke.
- To elucidate the underlying molecular mechanism involving signal transducer and activator of transcription 3 (STAT3).
Main Methods:
- Transient middle cerebral artery occlusion (tMCAO) in mice and oxygen-glucose deprivation/reperfusion (OGD/R) in microglial cells were used to model ischemic stroke.
- circPTP4A2 was knocked down using shRNA lentivirus, and STAT3 phosphorylation was modulated.
- Microglial polarization, inflammatory factors, infarct volume, and cerebral blood flow were assessed. RNA pull-down and RIP assays confirmed circPTP4A2 and STAT3 binding.
Main Results:
- circPTP4A2 levels were elevated in ischemic stroke models.
- circPTP4A2 knockdown reduced infarct volume, improved cerebral blood flow, and attenuated neurological deficits.
- circPTP4A2 knockdown suppressed M1 microglial polarization, promoted M2 polarization, and inhibited STAT3 phosphorylation, indicating a STAT3-dependent mechanism.
Conclusions:
- circPTP4A2 stimulates neuroinflammation in ischemic brain injury by promoting STAT3-dependent microglial polarization.
- circPTP4A2 knockdown mitigates cerebral ischemic injury and enhances M2 microglial polarization, identifying it as a potential therapeutic target for ischemic stroke.
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