Excessive expression of miR-27 impairs Treg-mediated immunological tolerance
Leilani O. Cruz, … , Aly Azeem Khan, Li-Fan Lu
Leilani O. Cruz, … , Aly Azeem Khan, Li-Fan Lu
Published January 9, 2017
Citation Information: J Clin Invest. 2017;127(2):530-542. https://doi.org/10.1172/JCI88415.
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Research Article Autoimmunity Immunology

Excessive expression of miR-27 impairs Treg-mediated immunological tolerance

Abstract

MicroRNAs (miRs) are tightly regulated in the immune system, and aberrant expression of miRs often results in hematopoietic malignancies and autoimmune diseases. Previously, it was suggested that elevated levels of miR-27 in T cells isolated from patients with multiple sclerosis facilitate disease progression by inhibiting Th2 immunity and promoting pathogenic Th1 responses. Here we have demonstrated that, although mice with T cell–specific overexpression of miR-27 harbor dysregulated Th1 responses and develop autoimmune pathology, these disease phenotypes are not driven by miR-27 in effector T cells in a cell-autonomous manner. Rather, dysregulation of Th1 responses and autoimmunity resulted from a perturbed Treg compartment. Excessive miR-27 expression in murine T cells severely impaired Treg differentiation. Moreover, Tregs with exaggerated miR-27–mediated gene regulation exhibited diminished homeostasis and suppressor function in vivo. Mechanistically, we determined that miR-27 represses several known as well as previously uncharacterized targets that play critical roles in controlling multiple aspects of Treg biology. Collectively, our data show that miR-27 functions as a key regulator in Treg development and function and suggest that proper regulation of miR-27 is pivotal to safeguarding Treg-mediated immunological tolerance.

Authors

Leilani O. Cruz, Somaye Sadat Hashemifar, Cheng-Jang Wu, Sunglim Cho, Duc T. Nguyen, Ling-Li Lin, Aly Azeem Khan, Li-Fan Lu

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Figure 7

Multiple Treg-suppressor molecules including IL-10 and GZMB are regulated by miR-27.

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Multiple Treg-suppressor molecules including IL-10 and GZMB are regulate...
(A) Clustering of RNA-seq results from R23Tg, R24Tg,R27Tg, and WT CD4+CD25hi Tregs based on total gene expression. (B) Scatter plot depicting the log2 fold changes of gene expression in naive R27Tg Tconvs over WT Tconvs versus R27Tg Tregs over WT Tregs. (C) Heatmap of the representative genes associated with Treg-suppressor function differentially expressed in YFP-Cre+ Tregs isolated from either Foxp3Cre/+ R27Tg or Foxp3Cre/+ control mice. (D) CDF plots depicting the effect of overexpression of miR-27 on mRNA expression of Treg-associated or all genes. mRNA levels of Treg-associated or all genes bearing HITS-CLIP–identified miR-27 sites (red line) were compared with mRNA levels of total Treg-associated or all genes (black line). HITS-CLIP analysis of the putative miR-27 site in the 3′-UTR of (E) IL-10 and (F) GZMB. Graph in G shows the ratios of repressed luciferase activity of cells in the presence of the GZMB 3′-UTR with or without mutations in the seed sequences in the presence of miR-27 compared with cells transfected with control miR. FACS analysis, ratio of frequencies, and MFI of (H) IL-10 and (I) GZMB in LP FOXP3+ Tregs with (YFP-Cre+) or without (YFP-Cre–) miR-27 overexpression. Tregs were from Foxp3Cre/+ R27Tg and Foxp3Cre/+ control mice. Data represent the mean ± SD and are representative of 3 independent experiments. Each symbol represents an individual mouse, and the bar represents the mean. *P < 0.05, **P < 0.01, and ***P < 0.001. P values are determined by an unpaired, 2-tailed Student’s t test.