Circ_0076490 silencing inhibits MAPK1 expression to decrease the proliferation and increase apoptosis of Jurkat cells by regulating miR-144-3p in myasthenia gravis.

Background: Myasthenia gravis (MG) is a both neuromuscular junction and antibody-mediated autoimmune disease, and its pathogenesis involves the regulation of circular RNAs (circRNAs). However, the role of circ_0076490 in MG and the underlying mechanism remain unknown.

Methods: RNA levels of circ_0076490, microRNA-144-3p (miR-144-3p), and mitogen-activated protein kinase 1 (MAPK1) were detected by quantitative real-time polymerase chain reaction. Cell viability and proliferation were investigated by cell counting kit-8 and 5-Ethynyl-29-deoxyuridine assays, respectively. Cell cycle and apoptosis were assessed by flow cytometry analysis. The putative binding relationship of miR-144-3p and circ_0076490 or MAPK1 was predicted by circular RNA interactome and TargetScan online databases, respectively, and identified through dual-luciferase reporter assay and RNA pull-down assay.

Results: We observed dramatic increases of circ_0076490 and MAPK1 expression and a decrease of miR-144-3p expression in the peripheral blood of MG patients in comparison with healthy controls. Reduced expression of circ_0076490 induced an inhibitory effect on the proliferation of Jurkat cells and a promoting effect on cell apoptosis. Additionally, miR-144-3p was identified as a target miRNA of circ_0076490, and its depletion attenuated circ_0076490 knockdown-mediated effects on the proliferation and apoptosis of Jurkat cells. MAPK1 was a target gene of miR-144-3p and its overexpression rescued decreased cell proliferation and increased cell apoptosis induced by miR-144-3p introduction. Furthermore, circ_0076490 regulated MAPK1 expression by interacting with miR-144-3p.

Conclusion: Circ_0076490 knockdown inhibited proliferation and induced apoptosis of Jurkat cells through the regulation of the miR-144-3p/MAPK1 axis, providing potential targets for developing improved therapy of MG.