Abstract: Abstract: Objective To explore the role and mechanism of histone lysine methyltransferase SET8 in the calcification of vascular smooth muscle cells (VSMCs) induced by high phosphorus. Methods The clean male SD rats weighting 80 g to 100 g were selected, and their thoracic aortae were taken for primary culture. VSMCs were passed to the 3rd to 4th generation, and the cells were plated into six-well plates, and then VSMCs were given corresponding stimulation. VSMCs were randomly divided into normal group and high phosphorus group (10 mmol/L β- glycerophosphate). The formation of calcium nodules was observed after four-day culture. Flow cytometry was used to detect the apoptosis of cells. The expression levels of mRNA and protein of SET8, p53, Bcl-2, Bax and Caspase3 were detected by RT-PCR and Western blot assay. Then SET8-shRNA plasmid was transfected into VSMCs that was used as SET8-shRNA group. The un-transfected group was used as normal control group. The effects of SET8 on mRNA and protein expression levels of p53, Bcl-2 Bax and Caspase3 were detected by RT-PCR and Western blot assay. Results (1) The calcium deposition was significantly increased in the high phosphorus group compared with that of normal group (P＜0.05). (2) The result of flow cytometry showed that compared with the normal group, the apoptosis rate of VSMCs was significantly increased in the high phosphorus group (P＜0.05). (3) Compared with the normal group, the expression levels of Bcl-2 and SET8 mRNA and protein were significantly decreased, and the expression levels of p53, Bax and Caspase3 increased in the high phosphorus group (P＜0.05). (4) Calcium salt deposition increased after interference with SET8 (P＜0.05). The expression level of Bcl-2 decreased and the expression levels of p53, Bax and Caspase3 increased after interference with SET8 gene expression (P＜0.05). Conclusion High phosphorylation regulates p53 / Bcl-2 / Caspase signaling pathway through SET8, down-regulates the expression of anti-apoptotic protein Bcl-2, up-regulates the expressions of pro-apoptotic proteins Bax and Caspase3, and then participates in the regulation of vascular smooth muscle cell calcification.

Key words: muscle, smooth, vascular, genes, p53, RNA interference, phosphatidic acids