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Published on: January 7, 2020
MicroRNA-29a regulates lipopolysaccharide (LPS)-induced inflammatory responses in murine macrophages through the
Bufu Tang1, Xingchen Li2, Yanling Ren1
1First Affiliated Hosp Dalian Med Univ, Dept Oncol, Dalian 116011, PR China.
Abstract:
Akt activation in macrophages enhances lipopolysaccharide (LPS)-induced inflammatory responses through upregulation of the NF-κB signal pathway. Akt phosphorylation via microRNA (miR) caused the downregulation of Akt1. Here, we evaluated the role of miR-29a in LPS-triggered inflammatory responses. LPS stimulation of primary macrophages and RAW264.7 cells gradually increased the levels of miR-29a and was dependent on the LPS concentration. Overexpression of miR-29a in macrophages enhanced the expression of proinflammatory cytokines including IL-1β and IL-6, but not TNF-α. Conversely, knockdown of miR-29a diminished cytokine expression. Bioinformatics analyses indicated that Akt1 was a potential target of miR-29a through its interaction with the CDS region of Akt1. The miR-29a also enhanced LPS-induced NF-κB signaling through increased NF-κB transcriptional activity and phosphorylation of p65, and through binding to Akt1. Moreover, Akt1 silencing promoted the LPS-induced expression of IL-1β and IL-6, and upregulated the NF-κB pathway. Taken together, our results suggested that miR-29a participates in the regulation of inflammatory responses in LPS-stimulated macrophages by promoting NF-κB activation through targeting Akt1.
Insights
MicroRNA-29a (miR-29a) amplifies inflammatory responses in macrophages stimulated by lipopolysaccharide (LPS). It targets Akt1, enhancing NF-κB signaling and promoting pro-inflammatory cytokine release.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Macrophage activation by lipopolysaccharide (LPS) involves inflammatory signaling pathways.
- MicroRNAs (miRNAs) regulate gene expression and play roles in immune responses.
- Akt signaling is implicated in inflammatory processes.
Purpose of the Study:
- To investigate the role of miR-29a in lipopolysaccharide (LPS)-induced inflammatory responses in macrophages.
- To elucidate the molecular mechanism by which miR-29a influences inflammatory signaling.
Main Methods:
- Primary macrophages and RAW264.7 cells were stimulated with LPS.
- miR-29a levels were measured using quantitative real-time PCR.
- Overexpression and knockdown of miR-29a were performed.
- Bioinformatics analyses identified potential miRNA targets.
- Western blotting assessed protein phosphorylation and expression.
- NF-κB transcriptional activity was measured.
Main Results:
- LPS stimulation increased miR-29a levels in a dose-dependent manner.
- Overexpression of miR-29a enhanced IL-1β and IL-6 expression, while knockdown diminished it.
- Akt1 was identified as a direct target of miR-29a.
- miR-29a promoted LPS-induced NF-κB signaling by increasing p65 phosphorylation and NF-κB transcriptional activity via Akt1.
- Akt1 silencing mimicked the effects of miR-29a overexpression on cytokine expression and NF-κB pathway activation.
Conclusions:
- miR-29a acts as a positive regulator of inflammatory responses in LPS-stimulated macrophages.
- The mechanism involves miR-29a targeting Akt1, leading to enhanced NF-κB pathway activation.
- These findings highlight miR-29a as a potential therapeutic target for inflammatory diseases.
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