[miR-338-5p modulates B cell biological functions by targeting NF-κB1]

Objective To explore the effects of miR-338-5p on the nuclear factor κB1 (NF-κB1) expression and the IgG-producing ability of B cells. Methods Dual-luciferase reporter assay was used to test the target gene of miR-338-5p. The purified CD20⁺ B cells were transfected with miR-338-5p agomiR, miR-338-5p antagomiR, NF-κB1 siRNA (siNF-κB1) and their corresponding negative control reagents, and then cultured with anti-IgM antibody and/or recombinant human B cell activating factor (rhBAFF). Real-time RCR and Western boltting were applied to determine the mRNA and protein levels of NF-κB1. IgG level in the supernatant was detected by ELISA. Results Compared with the control group, the hRluc/hLuc relative luciferase activity was significantly elevated in miR-338-5p mimic and NF-κB1-3'-UTR reporter co-transfected group. In the co-culture system with anti-IgM antibody and rhBAFF, the NF-κB1 mRNA, p105, p50 and IgG levels in B cells transfected with miR-338-5p agomiR were significantly increased, while the NF-κB1 mRNA and IgG levels in B cells transfected with miR-338-5p antagomiR were significantly decreased. The effect of siNF-κB1 on B cells was opposite to that of miR-338-5p agomiR. Correlation analysis suggested that NF-κB1 mRNA level was significantly positively correlated with IgG concentration. Conclusion miR-338-5p regulates the biological functions of B cells by positively regulating NF-κB1 expression and indirectly regulating BAFF signal.