Effect of U2AF1 Mutation to Inflammatory Cytokine Expression in SKM-1 Cells through FOXO3a-Bim Signaling Pathway

Abstract

To investigate the effect of U2AF1 gene mutation to inflammatory cytokine in SKM-1 cell of human myelodysplastic syndromes (MDS), and whether the above effects were mediated by FOXO3a-Bim signaling pathway. Wide-type U2AF1 and mutant U2AF1 (the serine residue 34 was replaced by phenylalanine, and named as S34F) recombinant expression plasmids were constructed. Lentiviruses were packaged and transfected into SKM-1 cells. The expression of FOXO3a was up-regulated by lentiviruses, and its transfection rate was investigated. The cell proliferation was detected by CCK-8 method. Flow cytometry was used to detect the apoptosis and cycle of the cells. The expression pro-inflammatory cytokine IL-1β, IL-6, TNF-α and anti-inflammatory cytokine IL-4 were detected by qRT-PCR. FOXO3a, Bim, Bcl-2 and Bax protein expression levels were detected by Western blot. Compared with the control group, the cell apoptosis rate, pro-inflammatory cytokine IL-1β and TNF-α transcription levels were significantly increased in the S34F group (P<0.05); cell cycle was blocked at the G2 phase; cell proliferation and the anti-inflammatory cytokine IL-4 transcription level were significantly decreased; the expression levels of FOXO3a, Bim and Bax protein were significantly increased (P<0.05); while the expression level of Bcl-2 protein was significantly decreased (P<0.05). The up-regulation of FOXO3a could significantly inhibited the proliferation and increased cell apoptosis of SKM-1 cells with U2AF1 S34F mutation; cell cycle was blocked at the S and G2 phases; the pro-inflammatory cytokine IL-1β and TNF-α transcription levels were significantly decreased (P<0.05), and the transcription level of anti-inflammatory cytokine IL-4 showed no statistically significant as compared with control group (P>0.05). U2AF1 S34F mutation can regulate inflammatory phenotype in SKM-1 cells, which may be mediated through FOXO3a-Bim signaling pathway.