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Published on: November 3, 2014
MicroRNA-301a directly targets IL-4/13A to negatively regulate Th2 immune responses in large yellow croaker
Huazhi Chen1, Jiamei Liu1, Yangfan Xiao1
1State Key Laboratory of Mariculture Breeding, Key Laboratory of Marine Biotechnology of Fujian Province, College of Marine Sciences, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Abstract:
Interleukin-4 (IL-4) and IL-13, predominantly secreted by T helper type 2 (Th2) cells, are pivotal cytokines involved in the Th2 response via the MAPK and mTOR signaling pathways. MicroRNAs (miRNAs) modulate various biological processes by inhibiting mRNA translation or facilitating mRNA degradation. However, research on miRNAs targeting IL-4 and IL-13 and their associated downstream signaling molecules remains limited. In this study, the miR-301a was identified for the first time as a potential regulator of IL-4/13A in Larimichthys crocea (Lc) through comprehensive analyses of miRNA-mRNA transcriptomes. The Lcpre-miR-301a comprises 86 nucleotides, including a 21-bp mature miRNA sequence. Secondary structure prediction showed that Lcpre-miR-301a can form a classic hairpin structure. Multiple sequence alignment revealed that the mature LcmiR-301a is highly conserved across fish, mammals, amphibians, and birds. The miR-301a was demonstrated to directly bind to the 3'-UTR of LcIL-4/13A. Upon induction with phytohemagglutinin (PHA), the expression levels of LcIL-4/13A were significantly upregulated, leading to the activation of T cell proliferation and differentiation, as well as B cell proliferation in primary head kidney leukocytes (PKLs). Conversely, the overexpression of miR-301a in PKLs significantly inhibited the PHA-induced upregulation of LcIL-4/13A expression level. Additionally, the stimulatory effects of PHA on T cells and B cells were diminished by the overexpression of LcmiR-301a. Moreover, after transfection with miR-301a mimics and subsequent induction with PHA, the phosphorylation levels of MEK1/2 and 4E-BP1, two critical signaling molecules within the MAPK and mTOR pathways, were significantly reduced in PKLs compared to induction with PHA alone. These findings suggest that miR-301a plays a crucial role in negatively regulating the Th2 immune response by targeting LcIL-4/13A. This study enhances our understanding of the mechanisms underlying miRNA regulation in the adaptive immune response of fish.
Insights
MicroRNA miR-301a regulates the fish immune response by targeting Interleukin-4/13A. Overexpressing miR-301a inhibits T helper 2 cell activation and downstream signaling, revealing a novel regulatory mechanism in fish adaptive immunity.
Area of Science:
- Immunology
- Molecular Biology
- Genetics
Background:
- Interleukin-4 (IL-4) and IL-13 are key cytokines in T helper type 2 (Th2) responses, mediated by MAPK and mTOR signaling pathways.
- MicroRNAs (miRNAs) regulate gene expression, but their role in targeting IL-4/13 and associated signaling molecules is not well understood.
- Limited research exists on miRNAs controlling IL-4/13 and their downstream effects in adaptive immunity.
Purpose of the Study:
- To identify and characterize miRNAs that regulate IL-4/13 expression in Larimichthys crocea (Lc).
- To investigate the function of miR-301a in modulating the Th2 immune response.
- To elucidate the impact of miR-301a on immune cell activation and downstream signaling pathways.
Main Methods:
- Comprehensive analysis of miRNA-mRNA transcriptomes to identify potential miRNA regulators of LcIL-4/13A.
- In vitro studies involving overexpression of LcmiR-301a in primary head kidney leukocytes (PKLs) from Lc.
- Phytohemagglutinin (PHA) induction to stimulate immune responses and assessment of cytokine expression, cell proliferation, and signaling pathway activation (MEK1/2, 4E-BP1 phosphorylation).
Main Results:
- miR-301a was identified as a direct regulator of LcIL-4/13A, binding to its 3'-UTR.
- Overexpression of miR-301a significantly inhibited PHA-induced LcIL-4/13A upregulation and suppressed T and B cell proliferation.
- miR-301a mimics reduced the phosphorylation of MEK1/2 and 4E-BP1, key components of the MAPK and mTOR pathways, respectively.
Conclusions:
- miR-301a negatively regulates the Th2 immune response in fish by targeting LcIL-4/13A.
- This study reveals a novel miRNA-mediated regulatory mechanism in fish adaptive immunity.
- Findings contribute to understanding the intricate interplay between miRNAs and immune signaling in aquatic vertebrates.
