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LncRNA MEG3 regulates microglial polarization through KLF4 to affect cerebral ischemia-reperfusion injury
Tianhao Li1, Yuru Luo1, Peng Zhang1
1Department of Neurosurgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
Abstract:
This study aimed to explore whether long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) affects the polarization of microglia in cerebral ischemia-reperfusion (I/R) injury through regulating Krüppel-like factor 4 (KLF4). A middle cerebral artery occlusion/reperfusion-induced (MCAO/R-induced) mouse model was established as an in vivo model. Oxygen and glucose confinement/reoxygenation-induced (OGD/R-induced) microglia (BV2 cells) were used as an in vitro model. RNA pull-down and RNA immunoprecipitation were used to detect the binding between MEG3 and KLF4. The MEG3 expression was signally elevated in the MCAO/R-induced mice or OGD/R-induced BV2 cells. The inhibition of MEG3 reversed the effects of OGD/R injury on the polarization and inflammation of BV2 cells. Moreover, MEG3 bound to KLF4 and inhibited its protein expression. Furthermore, the overexpression of MEG3 promoted M1 polarization and inflammation but inhibited M2 polarization by inhibiting KLF4 in BV2 cells. The transfection of small interfering RNAs against MEG3 inhibited M1 polarization and inflammation and promoted M2 polarization in vitro and in vivo. Inhibition of MEG3 can alleviate cerebral I/R injury via regulating the polarization of microglia through KLF4.NEW & NOTEWORTHY To study the role of long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) in cerebral ischemia-reperfusion (I/R) injury, we clarified the mechanism by which lncRNA MEG3 regulates the secretion of inflammatory cytokines in microglia through in vitro and in vivo experiments. We discovered that inhibition of MEG3 could alleviate cerebral I/R injury via inhibiting M1 polarization and promoting M2 polarization through Krüppel-like factor 4 (KLF4), indicating an effective theoretical basis for potential therapeutic targets of cerebral I/R injury.
Insights
Inhibition of maternally expressed gene 3 (MEG3) long noncoding RNA alleviates cerebral ischemia-reperfusion injury. This occurs by regulating microglial polarization via Krüppel-like factor 4, offering a therapeutic target.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Cerebral ischemia-reperfusion (I/R) injury involves complex inflammatory responses mediated by microglia.
- Microglial polarization into pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes plays a critical role in I/R injury.
- Long noncoding RNAs (lncRNAs) are emerging as key regulators in neurological disorders, but their specific roles in I/R-induced microglial polarization remain unclear.
Purpose of the Study:
- To investigate the role of long noncoding RNA maternally expressed gene 3 (MEG3) in regulating microglial polarization during cerebral I/R injury.
- To elucidate the underlying mechanism involving Krüppel-like factor 4 (KLF4).
- To assess the therapeutic potential of targeting MEG3 in cerebral I/R injury.
Main Methods:
- Establishment of in vivo (MCAO/R-induced mouse model) and in vitro (OGD/R-induced BV2 cells) models of cerebral I/R injury.
- Detection of MEG3 and KLF4 interaction using RNA pull-down and RNA immunoprecipitation assays.
- Assessment of microglial polarization (M1/M2) and inflammatory cytokine secretion following MEG3 manipulation (inhibition or overexpression).
Main Results:
- MEG3 expression was significantly elevated in both in vivo and in vitro models of cerebral I/R injury.
- MEG3 directly bound to KLF4 and inhibited its protein expression.
- Inhibition of MEG3 reversed OGD/R-induced M1 polarization and inflammation while promoting M2 polarization, both in vitro and in vivo.
- Overexpression of MEG3 promoted M1 polarization and inflammation, and inhibited M2 polarization by suppressing KLF4.
Conclusions:
- Long noncoding RNA MEG3 plays a critical role in regulating microglial polarization during cerebral I/R injury.
- MEG3 exacerbates I/R injury by promoting M1 polarization and inflammation through the inhibition of KLF4.
- Inhibition of MEG3 represents a promising therapeutic strategy for mitigating cerebral I/R injury by modulating microglial polarization.
