High-Phosphate-Induced Calcification Is Related to SM22α Promoter Methylation in Vascular Smooth Muscle Cells
High-Phosphate-Induced Calcification Is Related to SM22α Promoter Methylation in Vascular Smooth Muscle Cells
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DOI：
10.1002/jbmr.93
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发表时间：
2010-09-01
影响因子：
6.2
通讯作者：
Aguilera-Tejero, Escolastico
中科院分区：
文献类型：
--
作者：
Montes de Oca, Addy;Madueno, Juan A.;Aguilera-Tejero, Escolastico
慢性肾脏病患者高磷血症与血管钙化密切相关。体外暴露于高磷酸盐浓度的血管平滑肌细胞（VSMC）会发生向成骨细胞样细胞的表型转变。这种转分化的机制尚不清楚。在本研究中，我们使用人主动脉平滑肌细胞和大鼠主动脉环两种体外模型来研究高磷酸盐诱导的VSMCs表型转变。我们发现培养基中的高磷酸盐浓度（3.3 mmol/L）与 DNA 甲基转移酶活性增加和 SM22 α 启动子区域甲基化相关。伴随着平滑肌细胞特异性蛋白 SM22 α 的损失、成骨细胞转录因子 Cbfa1 的增加以及随后体外钙化的碱性磷酸酶活性的增加。在高磷酸盐培养基中添加去甲基化剂（普鲁卡因）可降低 DNA 甲基转移酶活性并阻止 SM22 α 启动子的甲基化，同时伴随着 SM22 α 表达的增加和钙化的减少。此外，通过 siRNA 或甲基供体（S-腺苷甲硫氨酸）下调 SM22 α，导致 Cbfa1 过度表达。总之，我们证明 SM22 α 启动子的甲基化是血管平滑肌细胞钙化的重要事件，并且高磷酸盐诱导这种表观遗传修饰。这些发现揭示了高磷酸盐浓度促进血管钙化机制的新见解。 (C) 2010 年美国骨与矿物质研究学会。
Hyperphosphatemia is closely related to vascular calcification in patients with chronic kidney disease. Vascular smooth muscle cells (VSMCs) exposed to high phosphate concentrations in vitro undergo phenotypic transition to osteoblast-like cells. Mechanisms underlying this transdifferentiation are not clear. In this study we used two in vitro models, human aortic smooth muscle cells and rat aortic rings, to investigate the phenotypic transition of VSMCs induced by high phosphate. We found that high phosphate concentration (3.3 mmol/L) in the medium was associated with increased DNA methyltransferase activity and methylation of the promoter region of SM22 alpha. This was accompanied by loss of the smooth muscle cell-specific protein SM22 alpha, gain of the osteoblast transcription factor Cbfa1, and increased alkaline phosphatase activity with the subsequent in vitro calcification. The addition of a demethylating agent (procaine) to the high-phosphate medium reduced DNA methyltransferase activity and prevented methylation of the SM22 alpha promoter, which was accompanied by an increase in SM22 alpha expression and less calcification. Additionally, downregulation of SM22 alpha, either by siRNA or by a methyl group donor (S-adenosyl methionine), resulted in overexpression of Cbfa1. In conclusion, we demonstrate that methylation of SM22 alpha promoter is an important event in vascular smooth muscle cell calcification and that high phosphate induces this epigenetic modification. These findings uncover a new insight into mechanisms by which high phosphate concentration promotes vascular calcification. (C) 2010 American Society for Bone and Mineral Research.