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Circular RNAs (circRNAs) represent a class of non-coding RNAs that form covalently closed RNA circles with extensive expression and conservation in mammals. Circular RNAs regulate gene expression through acting as competitive endogenous RNAs (ceRNAs) and modulating gene transcription. Accumulating evidence supports the implication of circRNAs in a variety of human diseases, but studies of circRNA role in systemic lupus erythematosus (SLE) are lacking. The present study measured the circRNA expression profiles in T cells from patients with SLE and healthy controls with human circRNA microarray and identified 127 differentially expressed circRNAs in SLE patients. Down-regulation of hsa_circ_0045272 in SLE T cells was verified with quantitative PCR. Jurkat cells with stable hsa_circ_0045272 knockdown were generated using specific lentiviral short hairpin RNA for functional studies. Flow cytometric analysis indicated that hsa_circ_0045272 knockdown significantly up-regulated the early apoptosis of Jurkat cells. Meanwhile, ELISA showed that hsa_circ_0045272 knockdown significantly enhanced interleukin-2 production of activated Jurkat cells. Then, ceRNAs were predicted for hsa_circ_0045272 and the significant down-regulation of two mRNAs predicted as ceRNAs, NM_003466 (PAX8) and NM_015177 (DTX4), but not their corresponding proteins, was validated. Furthermore, dual luciferase reporter assay indicated binding of hsa_circ_0045272 with hsa-miR-6127. Circular RNA-mRNA co-expression networks showed the correlation of circRNAs with mRNAs and provided additional clues to circRNA functions. Our study demonstrated dysregulated circRNAs in SLE and revealed the function of hsa_circ_0045272 in negatively regulating apoptosis and interleukin-2 secretion and its potential mechanism. The implication of hsa_circ_0045272 and other abnormal circRNAs in SLE merits further investigation.

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Competitive endogenous RNA (ceRNA) hypothesis proposes that RNA transcripts, both coding and non-coding, crosstalk with and coregulate each other using microRNA response elements (MREs). CeRNA analysis tremendously expands functional information of coding and non-coding RNAs. Mounting evidence have shown that various types of RNAs, including pseudogenes, long non-coding RNAs, circular RNAs, and messenger RNAs, can function as ceRNAs in distinct physiological and pathophysiological states. Many validated ceRNA pairs participate in the initiation and progression of cancers, and systemic ceRNA network analyses revealing potential of ceRNAs in diagnosis, therapy, and prognosis of cancers have also been performed. Areas covered: This review concisely introduces ceRNA hypothesis and characteristics of ceRNA regulations. The major sections focus on representative examples of both protein coding and non-coding RNA transcripts acting as ceRNAs. CeRNA prediction programs and databases and implications of ceRNA network in cancers are then discussed. In the end, we surmise potential implications of ceRNA network for SLE. Expert opinion: The role of ceRNA network in systemic lupus erythematosus (SLE) remains undefined. We speculate that dissecting ceRNA network in SLE may help expand our comprehension of roles of transcriptome, particularly non-coding transcripts, and richen our knowledge of pathogenesis, diagnosis, and therapy of SLE.

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