OBJECTIVETo explore the effects of MAPK antagonist on TPO stimulated UT7 cell proliferation and differentiation, and to elucidate the mechanism of TPO functioning on UT7 cells.

METHODSEGFP pMSCV and MEK 1 pMSCV MEK 1 plasmids were transferred into UT7 cells. Phosphorylated MEK1 of UT7 cells was examined by Western blot. The proliferation and CD41 expression of UT7 cells transfected with mutant (ser222A) MEK1 or exposed to PD98059 were examined.

RESULTS(1) 60.73% EGFP positive cells were obtained in retroviral vector MEK1 pMSCV transfected UT7cells. (2) In different time of TPO stimulating UT7 cells, the level of phosphorylated MEK1 was lower in experiment group than in control group. In experiment group, the level of phosphorylated MEK1 was decreased after stimulated by TPO for 1 hour, and almost disappeared after stimulated for 3 hours. (3) The effect of TPO on UT7 cell proliferation was inhibited by PD98059 and the transfected mutation MEK1 gene. The proliferation rate was 98.58% in DMSO control group, 39.00% in PD98059 group (P < 0.05), 102.13% in EGFP pMSCV group, and 48.94% in MEK1pMSCV (P < 0.05). (4) The CD41 expression on UT7 was inhibited by PD98059 and the transfected mutation MEK1 gene.

CONCLUSIONPhosphorylation of MEK1 in UT7 cells can be induced by TPO. There was a relationship between the TPO stimulating time and phosphorylation of MEK1. The effects of TPO on UT7 cell proliferation and CD41 expression is mediated by MAPK signal transduction pathway.