A transient reversal of miRNA‐mediated repression controls macrophage activation |
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Authors: | Anup Mazumder Mainak Bose Abhijit Chakraborty Saikat Chakrabarti Suvendra N Bhattacharyya |
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Institution: | 1. RNA Biology Research Laboratory, Molecular and Human Genetics Division, CSIR‐Indian Institute of Chemical Biology, , Kolkata, 700032 India;2. Structural Biology and Bioinformatics Division, CSIR‐Indian Institute of Chemical Biology, , Kolkata, 700032 India |
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Abstract: | In mammalian macrophages, the expression of a number of cytokines is regulated by miRNAs. Upon macrophage activation, proinflammatory cytokine mRNAs are translated, although the expression of miRNAs targeting these mRNAs remains largely unaltered. We show that there is a transient reversal of miRNA‐mediated repression during the early phase of the inflammatory response in macrophages, which leads to the protection of cytokine mRNAs from miRNA‐mediated repression. This derepression occurs through Ago2 phosphorylation, which results in its impaired binding to miRNAs and to the corresponding target mRNAs. Macrophages expressing a mutant, non‐phosphorylatable AGO2—which remains bound to miRNAs during macrophage activation—have a weakened inflammatory response and fail to prevent parasite invasion. These findings highlight the relevance of the transient relief of miRNA repression for macrophage function. |
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Keywords: | Ago2 phosphorylation lipopolysaccharide macrophage activation miRNA translational repression |
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