维生素 D 对足细胞钙敏感受体表达的影响简

目的观察活性维生素D（VitD）对足细胞钙敏感受体（CaSR）表达的影响，探讨其对足细胞保护作用的可能机制。方法体外分化培养的小鼠永生化足细胞随机分为：（1）正常对照组；（2）脂多糖（LPS）＋足细胞组；（3）LPS＋VitD＋足细胞组。AnnexinV-FITC／PI标记流式细胞测定足细胞的凋亡百分率，骨架蛋白F-肌动蛋白免疫荧光染色及半定量分析，Fura-2／AM负载检测细胞内Ca2＋浓度变化，Westernblot分别检测足细胞CaSR、p-ERKl／2蛋白的表达。结果LPS诱导足细胞凋亡，足细胞应力纤维及F-肌动蛋白减少，足细胞内的ca2＋浓度增加，CaSR、p-ERKl／2蛋白表达亦增加：而VitD明显减少LPS引起的足细胞凋亡，降低足细胞内的ca2＋浓度，部分恢复应力纤维及F-肌动蛋白结构，下调CaSR、p-ERKl／2蛋白的表达水平。结论VitD可能通过抑制CaSR-P-ERKl／2信号通路引起的细胞内ca2＋水平增加，拮抗LPS引起的足细胞凋亡，对足细胞有保护作用。

Effect of Vitamin D on Expression of Calcium-sensing Receptors in Podocytes

Objective To investigate the effect of vitamin D （VitD） on the expression of calcium-sensing receptors （CaSR） in podocytes, and to explore its role in podocyte protection. Methods Immortalized mouse podo- cytes in vitro were randomly divided into normal control group （ NC group）, LPS ＋ podocytes group （ LPS group）, and LPS ＋ VitD ＋ podocytes group （ LPS ＋ VitD group）. The percentage of podocyte apoptosis was detected by flow cytometry with annexin V FITC/PI double staining. Immunofluoresence staining and semi-quantitative analysis of cytoskeletal protein of F-actin was performed. Intracellular Ca2＋ concentration was measured by Fura-2/AM loading. The expression of CaSR and p-ERK1/2 proteins was detected by Western blotting. Results LPS administra- tion induced podocyte apoptosis. LPS treatment could decrease podocytic stress fibers and F-actin,increase the in- tracellular Ca2＋ concentration and upregulate the expression of CaSR and phosphorylation of ERK1/2. VitD signifi- cantly reduced podocyte apoptosis, reduced the intracellular Ca2＋ concentration in podocytes, partially restored the structures of podocytic stress fibers and F-actin, and decreased the expression of CaSR and phosphorylation of ERK1/2. Conclusion VitD reverses LPS-induced podocyte apoptosis, possibly by inhibiting CaSR-ERK1/2 signal pathway which increases intracellular Ca2＋ concentration, and has a protective effect on podocytes.