Vitamin-D receptor agonist calcitriol reduces calcification in vitro through selective upregulation of SLC20A2 but not SLC20A1 or XPR1.
Vitamin-D receptor agonist calcitriol reduces calcification in vitro through selective upregulation of SLC20A2 but not SLC20A1 or XPR1.
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DOI：
10.1038/srep25802
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发表时间：
2016-05-17
影响因子：
4.6
通讯作者：
Oliveira JR
中科院分区：
文献类型：
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作者：
Keasey MP;Lemos RR;Hagg T;Oliveira JR
维生素D缺乏(维生素D缺乏症)会导致骨软化和长骨矿化不良。与之形成明显对比的是，据报道，患有原发性脑钙化(“Fahr病”)的患者存在维生素D缺乏症。我们在体外钙化模型中评估了两个与初级脑钙化相关的磷酸转运蛋白(SLC20A2，其启动子具有预测的维生素D受体结合位点，以及XPR1)和一个不相关的(SLC20A1)的表达。在钙化性人骨肉瘤(SAOS-2)细胞中，这三种基因的表达均显著降低。此外，通过茜素红染色，我们证实维生素D(骨化三醇)减少了钙化。通过RT-qPCR，钙化条件下与骨化三醇孵育的细胞特异性地维持与对照相比更高水平的磷酸转运体SLC20A2的表达。骨化三醇对SLC20A1和XPR1均无影响，并保持抑制状态。关键是，用CRISPR技术在SaOs2细胞中敲除SLC20A2基因和蛋白可以显著抑制维生素D介导的钙化。本研究阐明了SLC20A2抑制钙化过程的机制重要性。这也表明维生素D可能被用来调节SLC20A2基因的表达，以及减少Fahr病和正常衰老中发生的脑钙化。
Vitamin D deficiency (hypovitaminosis D) causes osteomalacia and poor long bone mineralization. In apparent contrast, hypovitaminosis D has been reported in patients with primary brain calcifications (“Fahr’s disease”). We evaluated the expression of two phosphate transporters which we have found to be associated with primary brain calcification (SLC20A2, whose promoter has a predicted vitamin D receptor binding site, and XPR1), and one unassociated (SLC20A1), in an in vitro model of calcification. Expression of all three genes was significantly decreased in calcifying human bone osteosarcoma (SaOs-2) cells. Further, we confirmed that vitamin D (calcitriol) reduced calcification as measured by Alizarin Red staining. Cells incubated with calcitriol under calcifying conditions specifically maintained expression of the phosphate transporter SLC20A2 at higher levels relative to controls, by RT-qPCR. Neither SLC20A1 nor XPR1 were affected by calcitriol treatment and remained suppressed. Critically, knockdown of SLC20A2 gene and protein with CRISPR technology in SaOs2 cells significantly ablated vitamin D mediated inhibition of calcification. This study elucidates the mechanistic importance of SLC20A2 in suppressing the calcification process. It also suggests that vitamin D might be used to regulate SLC20A2 gene expression, as well as reduce brain calcification which occurs in Fahr’s disease and normal aging.