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J Allergy Clin Immunol. 2013 Aug;132(2):426-36.e8. doi: 10.1016/j.jaci.2013.02.005. Epub 2013 Apr 4.

MicroRNA-17/20a/106a modulate macrophage inflammatory responses through targeting signal-regulatory protein α.

Author information

1
Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China.

Abstract

BACKGROUND:

Signal-regulatory protein α (SIRPα) is an essential signaling molecule that modulates leukocyte inflammatory responses. However, the regulation of selective SIRPα synthesis and its dynamic changes in leukocytes under inflammatory stimulation remain incompletely understood.

OBJECTIVE:

We sought to identify the microRNAs (miRNAs) that posttranscriptionally regulate SIRPα synthesis and their roles in modulating macrophage inflammatory responses.

METHODS:

SIRPα was induced in SIRPα-negative promyelocytic cells by retinoic acid or phorbol 12-myristate 13-acetate, and the differential expression of miRNAs was assessed by means of microarray and quantitative RT-PCR assays. The roles of identified miRNAs in controlling SIRPα synthesis in leukocytes and leukocyte inflammatory responses were determined.

RESULTS:

We identified SIRPα as a common target gene of miR-17, miR-20a, and miR-106a. During SIRPα induction, levels of these 3 miRNAs were all reduced, and their downregulation by retinoic acid or phorbol 12-myristate 13-acetate occurred through suppression of the c-Myc signaling pathway. All miR-17, miR-20a, and miR-106a specifically bound to the same seed sequence within the SIRPα 3' untranslated region and correlated inversely with SIRPα protein levels in various cells. In macrophages upregulation of miR-17, miR-20a, and miR-106a by LPS served as the mechanism underlying LPS-induced SIRPα reduction and macrophage activation. Both in vitro and in vivo assays demonstrate that miR-17, miR-20a, and miR-106a regulate macrophage infiltration, phagocytosis, and proinflammatory cytokine secretion through targeting SIRPα.

CONCLUSION:

These findings demonstrate for the first time that miR-17, miR-20a, and miR-106a regulate SIRPα synthesis and SIRPα-mediated macrophage inflammatory responses in a redundant fashion, providing a novel pathway in which a panel of miRNAs can modulate immune polarization through regulation of macrophage activation.

KEYWORDS:

ASO; Antisense oligonucleotide; FITC; Fluorescein isothiocyanate; GAPDH; Galactosylated low-molecular-weight chitosan; Glyceraldehyde-3-phosphate dehydrogenase; ITIM; Immunoreceptor tyrosine-based inhibitory motif; Micro RNA; NO; Nitric oxide; Normal control RNA; PEI; Phorbol 12-myristate 13-acetate; Pre-normal control RNA; RA; Retinoic acid; SIRPα; SP-A; SP-D; Signal-regulatory protein α; Surfactant protein A; Surfactant protein D; TPA; UTR; Untranslated region; inflammatory response; macrophage; miRNA; microRNA; ncRNA; pre-ncRNA

PMID:
23562609
PMCID:
PMC5882493
DOI:
10.1016/j.jaci.2013.02.005
[Indexed for MEDLINE]
Free PMC Article

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