ABSTRACT
BACKGROUND: Circular RNAs are involved in autoimmune disease pathogenesis. Our previous study indicated that circPTPN22 is involved in autoimmune diseases, such as systemic lupus erythematosus (SLE) and rheumatoid arthritis, but the underlying mechanisms remain unclear. METHODS: First, the expression of circPTPN22 was detected by real-time PCR and western blotting. After overexpression or knockdown of circPTPN22, the proliferation of Jurkat cells was detected by the CCK-8 assay, and the apoptosis of Jurkat cells was detected by flow cytometry. In addition, the relationship between circPTPN22-miR-4689-S1PR1 was confirmed by bioinformatic analyses, fluorescence in situ hybridization assays, RNA-binding protein immunoprecipitation, and dual luciferase reporter assays. RESULTS: We found that circPTPN22 expression was downregulated in the PBMCs of SLE patients compared to those of healthy controls. Overexpression of circPTPN22 increased proliferation and inhibited apoptosis of Jurkat T cells, whereas knockdown of circPTPN22 exerted the opposite effects. CircPTPN22 acts as a miR-4689 sponge, and S1PR1 is a direct target of miR-4689. Importantly, the circPTPN22/miR-4689/S1PR1 axis inhibited the secretion of TNF-α and IL-6 in Jurkat T cells. CONCLUSIONS: CircPTPN22 acts as a miR-4689 sponge to regulate T-cell activation by targeting S1PR1, providing a novel mechanism for the pathogenesis of SLE.
Subject(s)
Lupus Erythematosus, Systemic , MicroRNAs , Protein Tyrosine Phosphatase, Non-Receptor Type 22 , RNA, Circular , Sphingosine-1-Phosphate Receptors , T-Lymphocytes , Humans , In Situ Hybridization, Fluorescence , Jurkat Cells , Lupus Erythematosus, Systemic/genetics , Lupus Erythematosus, Systemic/immunology , Lymphocyte Activation/genetics , Lymphocyte Activation/immunology , MicroRNAs/genetics , MicroRNAs/immunology , Protein Tyrosine Phosphatase, Non-Receptor Type 22/genetics , Protein Tyrosine Phosphatase, Non-Receptor Type 22/immunology , RNA, Circular/genetics , RNA, Circular/immunology , Sphingosine-1-Phosphate Receptors/genetics , Sphingosine-1-Phosphate Receptors/immunology , T-Lymphocytes/immunologyABSTRACT
The role of circular RNAs (circRNAs) in rheumatoid arthritis (RA) remains to be elucidated. To determine the expression of circRNAs in peripheral blood mononuclear cells (PBMCs) and to identify novel biomarkers for RA and explore their potential effects in RA, the present study conducted highthroughput RNA sequencing to analyze circRNA expression profiles in PBMCs from 4 RA patients and 3 healthy controls (HCs). Reverse transcriptionquantitative PCR was used to verify the expression of circPTPN22 in 42 RA patients, 44 HCs and 45 systemic lupus erythematosus (SLE) patients. In addition, bioinformatics analysis and Pearson's correlation test were conducted to assess the correlation of the relationships between circPTPN22 and RA progression. A receiver operating characteristic curve was calculated to evaluate the diagnostic value. Multilevel integrated analysis identified 41 upregulated and 30 downregulated circRNAs in RA patients compared with HCs. circPTPN22 was confirmed to be a common differentially expressed gene in RA and SLE compared with HCs. Area under the curve analysis suggested the diagnostic value of circPTPN22 expression to distinguish RA patients from both HCs and SLE patients. In addition, circPTPN22 levels in RA PBMCs were correlated with RAIgG, RAIgM, RAIgA, anticyclic citrullinated peptide (antiCCP), rheumatoid factor and C reactive protein levels. A total of four putative microRNAs (miRNAs or miRs), namely, hsamiR30745p, hsamiR3733p, hsamiR7663p and hsamiR34c5p, were screened to be sponged by circPTPN22 via bioinformatics analysis and then experimentally verified to be upregulated in RA PBMCs compared with controls. The data suggested that circPTPN22 might be a novel biomarker for the diagnosis of RA and participate in RA pathogenesis through a sponge mechanism.
