The down-regulation of hsa_circ_0012919, the sponge for miR-125a-3p, contributes to DNA methylation of CD11a and CD70 in CD4⁺ T cells of systemic lupus erythematous

Background: Systemic lupus erythematous (SLE) is an autoimmune disease characterized by the production of autoantibodies directed against various autoantigens. But the expression profiles and functions of circular RNAs (circRNAs) in SLE are still scarce. Objectives: To explore the roles of circRNA in SLE and its potential diagnostic potential in SLE. Methods: SLE patients and healthy control subjects were recruited. CD4⁺ T cells were isolated, circRNA microarray analysis were used to screen for circRNA candidate in CD4⁺ T cells. Expression of DNMT1, CD11a and CD70, and methylation level of CD11a and CD70 were detected after transfecting hsa_circ_0012919-targetted siRNA. The network analysis of hsa_circ_0012919 was used by bioinformatics. Luciferase reporter assay and fluorescence in situ hybridization (FISH) assay were used for screening for which miRNAs could bind with hsa_circ_0012919. Results: Twelve circRNAs were up-regulated and two circRNAs were down-regulated in SLE patients group after circRNA microarray analysis. Hsa_circ_0012919 was further confirmed to be significantly different between healthy control and SLE patients (P<0.05) and associated with SLE characters (P<0.05). Down-regulation of hsa_circ_0012919 (i) increased the expression of DNMT1 and reduced the expression of CD70, CD11a, (ii) reversed the DNA hypomethylation of CD11a and CD70 in CD4⁺ T cells of SLE, but it could be reversed by down-regulation of DNMT1. Hsa_circ_0012919 regulated KLF13 and RANTES by miR-125a. Conclusion: Hsa_circ_0012919 could be regarded as a biomarker for SLE and hsa_circ_0012919 was the competitive endogenous RNA (ceRNA) for miR-125a-3p.