Inserm Unit 1088, University of Picardie Jules Verne, 1 rue des Louvels, 80037 Amiens, France.
Cardiovasc Res. 2014 Feb 1;101(2):256-65. doi: 10.1093/cvr/cvt249. Epub 2013 Nov 11.
Vascular calcification (VC) contributes to morbidity and mortality in patients with chronic kidney disease (CKD). Allosteric modulators of the calcium (Ca)-sensing receptor (CaSR) may slow the progression of VC in CKD patients either by reducing serum parathyroid hormone (PTH), Ca, and phosphate levels or by a direct effect on the vessel wall. The aim of this study was to examine the effects of calcimimetics on CaSR expression, cell phenotype, and mineral deposition in human vascular smooth muscle cells (h-VSMCs).
Primary h-VSMCs were exposed for 14 days to increasing concentrations of Ca(2+) (from 1.8 to 5 mmol/L) in the presence or absence of calcimimetics R-568 or AMG 641 (0.1 μmol/L). Mineralization was detected by Alizarin red staining, and the cell phenotype was assessed using immunocytochemistry and qRT-PCR. CaSR expression was evaluated using flow cytometry. Short- and long-term exposure (1 day to 14 days) of h-VSMCs to calcimimetics promoted CaSR protein transport from the endoplasmic reticulum to the plasma membrane with enhanced CaSR expression on the cell surface, together with an increase in total cell CaSR expression due to enhanced biosynthesis. In pro-mineralizing conditions, exposure to calcimimetics counteracted the Ca(2+)-dependent reduction of CaSR expression, decreased matrix collagen secretion, and mineral deposition by ~90%. These effects involved CaSR activation since it could be inhibited by CaSR siRNA, but not scrambled siRNA.
The calcimimetic-dependent increase in biosynthesis and activation of the CaSR in h-VSMCs probably play a key role in the protection against calcium-induced VC.
血管钙化（VC）是导致慢性肾脏病（CKD）患者发病率和死亡率升高的主要原因。钙敏感受体（CaSR）的变构调节剂可通过降低血清甲状旁腺激素（PTH）、钙和磷酸盐水平，或者通过直接作用于血管壁，从而减缓 CKD 患者的 VC 进展。本研究旨在探讨钙敏感受体调节剂对人血管平滑肌细胞（h-VSMCs）中 CaSR 表达、细胞表型和矿物质沉积的影响。
原代 h-VSMCs 在存在或不存在钙敏感受体调节剂 R-568 或 AMG 641（0.1μmol/L）的情况下，分别用 1.8 至 5mmol/L 不同浓度的 Ca2+孵育 14 天。通过茜素红染色检测矿物质沉积，通过免疫细胞化学和 qRT-PCR 评估细胞表型。采用流式细胞术评估 CaSR 表达。h-VSMCs 短期（1 天至 14 天）和长期（14 天）暴露于钙敏感受体调节剂可促进 CaSR 蛋白从内质网向质膜转运，增加细胞表面的 CaSR 表达，同时由于增强了生物合成，总细胞 CaSR 表达增加。在促矿化条件下，钙敏感受体调节剂可拮抗 Ca2+依赖性 CaSR 表达降低，减少基质胶原分泌，使矿物质沉积减少约 90%。这些作用涉及 CaSR 激活，因为其可被 CaSR siRNA 抑制，但不能被 scrambled siRNA 抑制。
钙敏感受体调节剂依赖性增加 h-VSMCs 中 CaSR 的生物合成和激活，可能在保护细胞免受钙诱导的 VC 中发挥关键作用。
