IntroductionT-cell activation requires the T-cell receptor (TCR)-CD3 complex, which integrates and transduces signals. CD3ζ plays a vital role in TCR signalling by mediating T-cell activation. Abnormal CD3ζ expression is a common characteristic of haematological malignancies with T-cell immune dysfunction or autoimmune diseases. Targeted regulation of CD3ζ expression by either direct or indirect approaches is important for regulating T-cell activation.Aim of the studyIn this study, we focused on identifying miRNAs that may regulate CD3ζ expression.Material and methodsThree microRNA target search algorithms (TargetScan, PicTar, and microrna.org) were used to identify hypothetical miRNAs that target CD3ζ in T cells. Of the predicted miRNAs, miR-214 was chosen and validated to determine whether miR-214 directly binds to the CD3ζ 3’-UTR and regulates CD3ζ expression by luciferase reporter assays, real-time PCR, and Western blotting.ResultsThe results indicate that miR-214 specifically binds the CD3ζ 3’-UTR, and miR-214 mimics remarkably reduce the expression of CD3ζ in MOLT-4 cells.ConclusionsWe identify for the first time that miR-214 targets expression in MOLT-4 cells, suggesting that miR-214 might negatively regulate T-cell activation by targeting CD3ζ.
Background
Aplastic anemia (AA) is known as an autoimmune disease in which T cell activation is aberrant. It has been reported that unconventional T cells, mucosal‐associated invariant T (MAIT) cells, play an important role in several autoimmune diseases, but it is unclear if they are involved in AA.
Methods
In this study, we for the first time analyzed the proportions, phenotypes, and cytokine properties of MAIT cells in AA by flow cytometry.
Results
We found that the percentage of circulating MAIT cells was generally higher for CD3+, CD8+, and CD8− T cells in AA patients compared with healthy individuals. Moreover, the percentage of IL‐18Rα‐, NKG2D‐, IFN‐γ‐, and TNF‐α‐ positive MAIT cells was also significantly higher in AA patients. In addition, the percentage of IFN‐γ+ CD3+ or TNF‐α+CD8− MAIT cells had a significant negative correlation with the absolute neutrophil count.
Conclusions
We present the first observation of MAIT cells in patients with AA. MAIT cells are associated with a higher frequency of IFN‐γ and TNF‐α production and may contribute to the pathogenesis of AA.
Aberrant T cell activation is a major cause of aplastic anemia (AA) pathogenesis. Recent studies have shown that miRNAs regulate T cell activation and are involved in AA. A previous study found that miR-214 was significantly up-regulated upon T cell activation in a CD28-dependent fashion by targeting PTEN. However, the expression characteristics of miR-214 and its target genes in AA have not been defined. In this study, target genes for miR-214 were predicted and confirmed by bioinformatics and luciferase reporter assays. The expression levels of miR-214 and target genes were detected in 36 healthy individuals and 35 patients with AA in peripheral blood mononuclear cells by real-time quantitative reverse transcriptase-polymerase chain reaction. Bioinformatics and luciferase reporter assays identified that miR-214 could bind to the A20 3′ untranslated regions. Significantly increased miR-214 and the decreased A20 expression level were detected in the AA patients compared with the healthy group. In addition, significantly increased miR-214 was found in non-severe aplastic anemia compared with severe aplastic anemia patients. These results suggested that the A20 gene was a potential target of miR-214, and elevated miR-214 might medicate T cell activation at least in part by regulating A20 expression in AA. We firstly confirmed that miR-214 regulated A20 expression, and aberrant miR-214/A20 expression might contribute to immunopathology in AA. The miR-214 expression might be used as a potential biomarker that assisted in diagnosing AA severity.
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