p47phox and reactive oxygen species production modulate expression of microRNA-451 in macrophages

Abstract

The production of microRNAs (miRNA) is influenced by various stimuli, including environmental stresses. We hypothesized that reactive oxygen species (ROS)-associated stress could regulate macrophage miRNA synthesis. miRNAs undergo unique steps of maturation processing through either one of two pathways of cytoplasmic processing. Unlike the canonical pathway, the regulation of alternative cytoplasmic processing of miRNA has not been fully elucidated yet. We cultured bone marrow derived macrophages (BMDM) from wild type (WT) and p47^phox−/− mice and profiled miRNA expression using microarrays. We analyzed 375 miRNAs including four endogenous controls to normalize the data. At resting state, p47^phox−/− BMDM has the markedly reduced expression of miR-451 compared to WT BMDM, without other significant differences. Unlike majority of miRNAs, miR-451 goes through the unique alternative processing pathway, in which Ago2 plays a key role. In spite of significant reduction of mature miR-451, however, its precursor form, pre-mir-451, was similar in both BMDMs, suggesting that the processing of pre-mir-451 is impaired in p47^phox−/− BMDM. Moreover, p47^phox−/− BMDM expressed significantly reduced level of Ago2. In contrast, Ago2 mRNA levels were similar in WT and p47^phox−/− BMDM, suggesting a post-transcriptional defect of Ago2 production in p47^phox−/− macrophages, which resulted in impaired processing of pre-miR-451. In order to examine the functional significance of miR-451 in macrophages, we cultured BMDMs from miR-451 knock-out mice. Of interest, miR-451-deficient BMDM exhibited reduced ROS generation upon zymosan stimulation, compared to WT BMDM. Our studies suggest functional crosstalk between ROS and miR-451 in the regulation of macrophage oxidant stress.

Keywords::

• macrophages
• reactive oxygen species
• stress
• microRNA
• NADPH oxidase
• p47phox

Declaration of interest

The authors report no declarations of interest. The authors alone are responsible for the content and writing of the paper.

This work was supported by National Institutes of Health Grants R01 HL075557, HL068610, 5R01 HL083218, 3R01 HL083218-01A2S1, T32HL082547, Professional Development Award from the UIC CCTS (NIH-NCATS, UL1TR000050) and Department of Veterans Affairs Merit Review Grant 5I01BX000108.

Supplementary material available online

Supplementary Figures 1–3 to be found online at http://informahealthcare.com/doi/abs/10.3109/10715762.2014.974037.