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Updated: May 18, 2026
Detection of MicroRNAs in Microglia by Real-time PCR in Normal CNS and During Neuroinflammation
Published on: July 23, 2012
The microRNA miR-181c controls microglia-mediated neuronal apoptosis by suppressing tumor necrosis factor
Li Zhang1, Lian-Yan Dong, Ya-Jian Li
1Department of Neurology, Huadong Hospital, Fudan University, 221 West Yan An Road, Shanghai, 200040, China.
Background:
Post-ischemic microglial activation may contribute to neuronal damage through the release of large amounts of pro-inflammatory cytokines and neurotoxic factors. The involvement of microRNAs (miRNAs) in the pathogenesis of disorders related to the brain and central nervous system has been previously studied, but it remains unknown whether the production of pro-inflammatory cytokines is regulated by miRNAs.
Methods:
BV-2 and primary rat microglial cells were activated by exposure to oxygen-glucose deprivation (OGD). Global cerebral ischemia was induced using the four-vessel occlusion (4-VO) model in rats. Induction of pro-inflammatory and neurotoxic factors, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and nitric oxide (NO), were assessed by ELISA, immunofluorescence, and the Griess assay, respectively. The miRNA expression profiles of OGD-activated BV-2 cells were subsequently compared with the profiles of resting cells in a miRNA microarray. BV-2 and primary rat microglial cells were transfected with miR-181c to evaluate its effects on TNF-α production after OGD. In addition, a luciferase reporter assay was conducted to confirm whether TNF-α is a direct target of miR-181c.
Results:
OGD induced BV-2 microglial activation in vitro, as indicated by the overproduction of TNF-α, IL-1β, and NO. Global cerebral ischemia/reperfusion injury induced microglial activation and the release of pro-inflammatory cytokines in the hippocampus. OGD also downregulated miR-181c expression and upregulated TNF-α expression. Overproduction of TNF-α after OGD-induced microglial activation provoked neuronal apoptosis, whereas the ectopic expression of miR-181c partially protected neurons from cell death caused by OGD-activated microglia. RNAinterference-mediated knockdown of TNF-α phenocopied the effect of miR-181c-mediated neuronal protection, whereas overexpression of TNF-α blocked the miR-181c-dependent suppression of apoptosis. Further studies showed that miR-181c could directly target the 3'-untranslated region of TNF-α mRNA, suppressing its mRNA and protein expression.
Conclusions:
Our data suggest a potential role for miR-181c in the regulation of TNF-α expression after ischemia/hypoxia and microglia-mediated neuronal injury.
Insights
MicroRNA-181c (miR-181c) protects neurons from damage caused by activated microglia after ischemic events. This microRNA (miRNA) directly targets and reduces the expression of tumor necrosis factor-alpha (TNF-α), a key inflammatory factor.
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Biology
Background:
- Microglial activation post-ischemia releases inflammatory cytokines, contributing to neuronal damage.
- MicroRNAs (miRNAs) are implicated in central nervous system disorders, but their role in regulating microglial cytokine production is unclear.
Purpose of the Study:
- To investigate the role of miRNAs in regulating pro-inflammatory cytokine production by microglia following ischemic conditions.
- To determine if miR-181c influences tumor necrosis factor-alpha (TNF-α) expression and subsequent neuronal injury.
Main Methods:
- Oxygen-glucose deprivation (OGD) and a four-vessel occlusion (4-VO) rat model were used to induce ischemic conditions in microglial cells and in vivo.
- Pro-inflammatory factors (TNF-α, IL-1β, NO) were quantified using ELISA, immunofluorescence, and Griess assay.
- miRNA microarray analysis identified differentially expressed miRNAs; miR-181c's function was assessed via transfection, and its direct targeting of TNF-α was confirmed using a luciferase reporter assay.
Main Results:
- OGD and global cerebral ischemia induced microglial activation and the release of TNF-α, IL-1β, and NO.
- miR-181c expression was downregulated, while TNF-α expression was upregulated following OGD.
- Overexpression of miR-181c reduced OGD-induced microglial TNF-α production and protected neurons from apoptosis; knockdown of TNF-α mimicked this protective effect, confirming miR-181c directly targets TNF-α mRNA.
Conclusions:
- miR-181c plays a significant role in regulating TNF-α expression in microglia under ischemic/hypoxic conditions.
- miR-181c offers neuroprotection against microglia-mediated injury following ischemia/hypoxia by suppressing TNF-α.
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