MicroRNA Profiling And Functional Study In Systemic Lupus Erythematosus

MicroRNAs(miRNAs) are small, singal-stranded noncoding RNAs, many of which have been highly conserved throughout evolution. Currently, miRNA is known to regulate cellular processes such as differentiation, cell cycle, apoptosis and immune functions. The known function of miRNAs is the post-transcriptional regulation of certain subsets of messenger RNAs(mRNAs) by binding to their 3'untranslated region(UTR) thus targeting them for degradation or translational repression. To date, the miRNA sequence database, miRbase, includes over 9000 predicted miRNA in numerous species of plants, animals, and viruses. For humans alone, miRBase lists over 1000 predicted miRNAs, and other bioinformatics predictions indicate that as much as one-third of all mRNAs may be regulated by miRNA. More than 100 different miRNAs are expressed by cells of the immune system. They have the potential to broadly influence the molecular pathways that control the development, and function of innate and adaptive immune response by regulating target mRNA expression. The latest research demonstrated that some miRNAs are closely correlated with occurrence, development and prognosis of some diseases, which can be adopted as diagnostic and prognostic index for disease. SLE is a prototypic autoimmune disease with a diverse array of clinical manifestations, which is characterized by the production of antibodies to components of the cell nucleus. The pathogenesis of SLE is poorly understood, and current therapies are based on nonspecific immunosuppression. To date, little is known about the SLE-specific miRNAs expression profile and the roles of miRNAs in SLE pathogenesis. To study SLE-related miRNAs, an important srarting point is to examine expression profile of miRNAs in PBMC. In this study, we developed a novel miRNA-specific microarray, screened a set of SLE-related miRNAs, and further predicted their targets by bioinformatics and valited it by dual-luciferase reporter transfection assay.Objective This study was undertaken to explore microRNA expression profile in peripheral blood cells of patients with SLE, and to study the potential biological functions of the associated miRNA in the pathogenesis of SLE.Methods In this study, a total of 58 patients with available clinical data and 26 normal controls were enrolled to study the role of miRNA in SLE.4 patients and 4 normal controls were used for miRNA microarray analysis to detecting the levels of 847 miRNAs in peripheral blood cells. The rest were used for qRT-PCR confirmation and fulfill miRNA functional study. Reporter gene assay was conducted to determine the biological function of miR-125b.Results We performed a miRNA profiling analysis to 4 SLE patients using the 847 human mature miRNAs and obtained a set of SLE-specific miRNAs, such as miR-125b, miR-326, miR-26a ect. Eleven miRNAs were up-regulated, twenty-six miRNAs were down-regulated. The difference of expression in these miRNAs suggests that a unique SLE-specific miRNA profiling exists. Further analysis showed that underexpression of miR-125b mainly in T cell negatively correlated with organ involvement. To further demonstrate the role of miR-125b, we predicted its putative target using TargetScan software and chosen several potential targets. Then we validated Etsl, TNFAIP3 and STAT3 were targets of miR-125b by dual-luciferase reporter transfection assay.Conclusion Our findings revealed that miRNA expression profile may serve as a new biomarker of SLE. Underexpression of miR-125b mainly in T cells contributed to SLE progression, by targeting the gene Ets1, TNFAIP3 and STAT3 which would not only elucidate the novel pathogenic machanism in SLE, but also lay a foundation for new drug development based on miR-125b.