Identification of microRNA-31 as a novel regulator contributing to impaired interleukin-2 production in T cells from patients with systemic lupus erythematosus.
OBJECTIVE
MicroRNAs (miRNAs) function to fine-tune the control of immune cell signaling. It is well established that there are abnormalities in the interleukin-2 (IL-2)-related signaling pathways in systemic lupus erythematosus (SLE). The miR-31 microRNA has been found to be markedly underexpressed in patients with SLE, and thus the present study was undertaken to investigate the role of miR-31 in IL-2 defects in lupus T cells.


METHODS
Expression levels of miR-31 were quantitated using TaqMan miRNA assays. Transfection and stimulation of cultured cells followed by TaqMan quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and reporter gene assays were conducted to determine the biologic function of miR-31. NF-AT nuclear translocation and expression were quantitatively measured using an ImageStream cytometer. Bioinformatics analysis, small interfering RNA (siRNA) knockdown, and Western blotting were performed to validate miR-31 targets and effects.


RESULTS
The expression of miR-31 was significantly decreased in lupus T cells, and this was positively correlated with the expression of IL-2. Overexpression of miR-31 in T cells increased the production of IL-2 by altering NF-AT nuclear expression and IL2 promoter activity, while knockdown of endogenous miR-31 reduced IL-2 production. RhoA expression was directly repressed by miR-31 in T cells. Of note, siRNA-mediated knockdown of RhoA enhanced IL2 promoter activity and, consequently, up-regulated IL-2 production. RhoA expression was consistently up-regulated and negatively correlated with the levels of miR-31 in lupus T cells. Manipulation of miR-31 expression in lupus T cells restored the expression of IL-2 at both the messenger RNA and protein levels.


CONCLUSIONS
MicroRNA-31 is a novel enhancer of IL-2 production during T cell activation. Dysregulation of miR-31 and its target, RhoA, could be a novel molecular mechanism underlying the IL-2 deficiency in patients with SLE.
Joint Molecular Rheumatology Laboratory of the Institute of Health Sciences, Shanghai JiaoTong University School of Medicine, Chinese Academy of Sciences, China.
Wei
W
Fan
Dong
D
Liang
Yuanjia
Y
Tang
Bo
B
Qu
Huijuan
H
Cui
Xiaobing
X
Luo
Xinfang
X
Huang
Shunle
S
Chen
Brandon W
BW
Higgs
Bahija
B
Jallal
Yihong
Y
Yao
John B
JB
Harley
Nan
N
Shen
D005786:Gene Expression Regulation / Q000235:genetics / Q000276:immunology; D006801:Humans; D007376:Interleukin-2 / Q000172:deficiency / Q000235:genetics* / Q000276:immunology; D019169:Jurkat Cells; D008180:Lupus Erythematosus, Systemic / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D035683:MicroRNAs / Q000276:immunology*; D050778:NFATC Transcription Factors / Q000235:genetics / Q000276:immunology; D061251:Primary Cell Culture; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000276:immunology; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000276:immunology
C508594:IL2 protein, human; D007376:Interleukin-2; C534612:MIRN31 microRNA, human; D035683:MicroRNAs; D050778:NFATC Transcription Factors; D034741:RNA, Small Interfering; D020742:rhoA GTP-Binding Protein