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Published on: January 30, 2014
A Novel Effect of Id2 in Microglia TNFα Regulation
Wenhui Wang1, Asiru1, Guoya Luo1
1Neurobiology Research Center, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, No. 66, Gongchang Road, Guangming District, Shenzhen, Guangdong, 518107, People's Republic of China.
Abstract:
Microglia are the most important immune cells in the central nervous system (CNS), which can defend against external pathogens and stimuli. Dysregulation of microglia releases excessive proinflammatory cytokines and leads to neuroinflammation, which is fundamental to the pathophysiology of multiple neurological diseases. However, the molecular mechanisms underlying the regulation of proinflammatory cytokines in microglia are still not well-understood. Here, we identified that inhibitor of DNA binding protein 2 (Id2) was a negative regulator of tumor necrosis factor-α (TNFα) in cultured microglia. Knockdown of Id2 significantly increased the expression of TNFα in microglia, while overexpression of Id2 inhibited TNFα expression. Furthermore, by interacting with the p65 subunit of nuclear factor kappa-B (NF-κB), Id2 suppressed the transcription activation of NF-κB and inhibited TNFα expression. Interestingly, in lipopolysaccharides (LPS)-treated microglia, Id2 increased and underwent a cytoplasmic relocation. Immunoprecipitation and immunostaining results showed that by binding to the LIM domain of Id2, a scaffold protein PDZ and LIM 5 (PDLIM5) involved in the Id2 cytoplasmic relocation, which inactivated Id2 and resulted in higher TNFα expression in LPS-treated microglia. Collectively, our data delineate a novel effect of Id2 on TNFα regulation in microglia, which may shed a light on the proinflammatory cytokines regulating in microglia associated neuroimmune disorders.
Insights
Inhibitor of DNA binding protein 2 (Id2) negatively regulates the inflammatory cytokine tumor necrosis factor-alpha (TNFα) in microglia. PDZ and LIM 5 (PDLIM5) protein interaction with Id2 promotes TNFα release, contributing to neuroinflammation.
Area of Science:
- Neuroimmunology
- Cellular and Molecular Neuroscience
Background:
- Microglia are key immune cells in the central nervous system (CNS), crucial for defense but implicated in neuroinflammation when dysregulated.
- Neuroinflammation, driven by excessive proinflammatory cytokines from microglia, is central to many neurological diseases.
- The precise molecular mechanisms controlling microglial proinflammatory cytokine production remain incompletely understood.
Purpose of the Study:
- To elucidate the role of Inhibitor of DNA binding protein 2 (Id2) in regulating proinflammatory cytokine production in microglia.
- To investigate the interaction between Id2, nuclear factor kappa-B (NF-κB), and tumor necrosis factor-alpha (TNFα) signaling.
- To identify novel regulatory factors involved in microglial activation and neuroinflammation.
Main Methods:
- Primary microglia cultures were used to assess Id2 function.
- Gene manipulation techniques (knockdown and overexpression) were employed to study Id2's effect on TNFα expression.
- Co-immunoprecipitation and immunostaining were utilized to investigate protein-protein interactions and subcellular localization.
- NF-κB transcriptional activity was assessed in response to Id2 modulation.
Main Results:
- Id2 was identified as a negative regulator of TNFα expression in microglia.
- Knockdown of Id2 increased TNFα levels, while Id2 overexpression suppressed it.
- Id2 inhibited TNFα transcription by interacting with the p65 subunit of NF-κB.
- Lipopolysaccharide (LPS) treatment induced Id2 upregulation and cytoplasmic relocation.
- The scaffold protein PDZ and LIM 5 (PDLIM5) binds to Id2, promoting its cytoplasmic relocation and inactivation, leading to increased TNFα release in LPS-treated microglia.
Conclusions:
- Id2 acts as a critical negative regulator of TNFα in microglia.
- PDLIM5-mediated cytoplasmic relocation of Id2 is a novel mechanism for activating TNFα production.
- These findings offer insights into the molecular control of microglial inflammation and potential therapeutic targets for neuroimmune disorders.
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