INHIBITION OF CELL CYCLE KINASE EXPRESSION BY TSP1 MEDIATED BY CD47 INHIBITS CELL CYCLE AND PROMOTES VASCULAR ENDOTHELIAL CELL SENESCENCE

Objective: To investigate the mechanism and effect of platelet-reactive protein (TSP1) on the cell cycle of vascular endothelial cells (VECs). Methods: Clean C57BL/6J mice and cd47ko mice with C57BL/ 6J background were collected. The microvascular endothelial cells of C57BL/6J mice were used as a WT group, and the microvascular endothelial cells of C57BL/6J mice were used as a cd47ko group, 6 in each. At the second passage (P-2), the fourth passage (P-4), and the sixth passage (P-6), the aging cell ratio of the two groups were compared with emphasis on their S-phase ratio, the expression level of cyclin D1, CDK4, Cdk6, and TSP1 mRNA. The endothelial cells of the WT and cd47ko group were divided into a control group, a TSP1 group, and an anti-TSP1 group. The expression level of CDK4, Cdk6, and cyclin D1 mRNA was documented in both the control and TSP1 groups. Results: When the cells were classified as P-4 and P-6, the aging rate of endothelial cells in the cd47ko group was significantly lower than that in the WT group, and the proportion of S-phase cells was noticeably higher than that in the WT group (P<0.05). The expression of Cdk6 mRNA in endothelial cells of the cd47ko group was considerably higher than that of the WT group (P<0.05). The expression of CDK4, Cdk6, and cyclin D1 mRNA in endothelial cells of the cd47kd group was substantially higher than that of the WT group (P<0.05). The expression of cyclin D1 mRNA in the cd47ko group was significantly higher than that in the WT group (P<0.05). The expression of TSP1 mRNA in endothelial cells of the cd47ko group was lower than that of the WT group (P<0.05). There existed no notable difference between the TSP-1 group and the control group (P>0.05). The senescence of WT cells in the anti-tsp1 group dropped compared to the TSP-1 group (P<0.05). The expression of CDK4, Cdk6, and cyclin D1 mRNA in the TSP1 group was significantly lower than that in the control group (P<0.05). There was no appreciable difference in CDK4, Cdk6, cyclin D1 mRNA expression between the TSP1 and control group (P>0.05). Conclusion: TSP1 can inhibit the expression of cyclin by CD47, and then promote the senescence of vascular endothelial cells.