摘要:
目的 探讨瞬时受体电位M7(TRPM7)在地塞米松诱导的小梁细胞骨架重塑中的作用.方法 采用人小梁细胞株进行体外培养,第3~6代小梁细胞用于实验.采用免疫荧光检测技术对TRPM7在小梁细胞中的表达进行定位.在细胞培养基中加入0.2 mg地塞米松处理小梁细胞4d,终浓度分别为1×10-5、1×10-6和1×10-7 mol/L,采用Western blot法检测细胞中TRPM7蛋白在细胞中的表达量.将培养的小梁细胞分为正常对照组、siRNA转染组、TRPM7-siRNA1转染组和TRPM7-siRNA2转染组,采用Western blot法检测细胞中TRPM7和p-cofilin相对蛋白表达量.将培养的细胞分为正常对照组、TRPM7-siRNA转染组、地塞米松处理组和TRPM7-siRNA转染+地塞米松组,采用免疫荧光技术法观察各组细胞中细胞骨架蛋白Phalloidin和黏着斑蛋白Vinculin的表达.将培养的细胞分为正常对照组、地塞米松处理组、siRNA转染组、TRPM7-siRNA转染组、TRPM7抑制剂2-APB处理组和钙离子螯合剂EGTA处理组,采用免疫荧光技术测定各组细胞内钙离子荧光强度变化. 结果 TRPM7主要分布于小梁细胞的细胞膜,TRPM7蛋白相对表达量随着地塞米松剂量的增加而逐渐下降,组间总体比较差异有统计学意义(F=4.210,P<0.05),1×10-5 mol/L地塞米松组细胞中TRPM7蛋白表达量明显低于正常对照组,差异有统计学意义(P=0.011).与正常对照组和siRNA转染组比较,TRPM7-siRNA1组和TRPM7-siRNA2组细胞中TRPM7蛋白相对表达量均明显降低,差异均有统计学意义(均P<0.05).倒置显微镜下可见地塞米松处理组和TRPM7-siRNA转染组细胞突起减少,细胞体稍变大.免疫荧光法显示地塞米松处理组小梁细胞骨架张力纤维和黏着斑蛋白增多,TRPM7-siRNA转染组细胞中张力纤维变少、变细.与正常对照组和siRNA转染组比较,地塞米松处理组和TRPM7-siRNA转染组细胞内钙离子荧光强度变弱.Western blot检测显示,TRPM7-siRNA转染组细胞中p-confilin蛋白相对表达量明显低于siRNA转染组(0.317±0.031 vs.0.092±0.071),差异有统计学意义(t=5.030,P=0.007). 结论 高剂量地塞米松作用后可导致小梁细胞中TRPM7蛋白表达量下调,TRPM7蛋白下调可能通过使小梁细胞骨架微丝蛋白解聚和细胞内钙离子浓度的降低而参与地塞米松诱导的小梁细胞中细胞骨架的重塑.%Objective To investigate the effects of transient receptor potential melastatin (TRPM) 7 on dexamethasone (Dex)-mediated cytoskeleton remodeling in human trabecular meshwork.Methods Human trabecular meshwork cells (HTMs) were primarily cultured and the cells of generation 3 to 6 were used in this study.The expression of TRPM7 protein in the cells was located using immunofluorescence technology.Dex at the dose of 0.2 mg was added into culture medium for 4 days with the final concentration of 1×10-5,1×10-6 and 1×10-7 mol/L,respectively.Western blot assay was employed to detect the relative expression level of TRPM7 protein.Cultured cells were divided into non-transfected group,siRNA transfected group,TRPM7-siRNA1 transfected group and TRPM7-siRNA2 transfected group,and the expressions of TRPM7 protein and p-cofilin protein in the cells were assayed by Western blot method.Cultured cells were divided into normal control group,Dex-treated group,siRNA transfected group and TRPM7-siRNA transfected group,and the expression of phalloidin (a cytoskeletal protein) and Vinculin (focal adhesion protein) was detected by immunofluorescence staining.In addition,cultured cells were divided into normal control group,Dex-treated group,2-APB (a Ca2+ inhibitor) treated group,ethylene glycol tetraacetic acid (EGTA) (a calcium chelator)-treated group,TRPM7-siRNA transfected group and TRPM7-siRNA+Dex group,and the [Ca2+] i in the cells was observed by Fluo-3AM immunofluorescence staining.Western blot assay was used to detect the expression of p-cofilin in the cells.Results TRPM7 was positively expressed on the cell membrane.The relative expression of TRPM7 was gradually reduced with an increase of Dex dose (F=4.210,P<0.05),and the expression of TRPM7 was significantly decreased in 1 × 10-5 mol/L Dex group compared with the normal control group (P< 0.05).Western blot assay revealed that the relative expression levels of TRPM7 in the TRPM7-siRNA1 and TRPM7-siRNA2 group were significantly lower than those of non-siRNA transfected group and siRNA transfected group (all at P<0.05).In the Dex-treated group and TRPM7-siRNA transfected group,the cells were enlarged in size with the lessened processes in comparison with the normal control group.Immunofluorescence staining showed that the actin fiber and vinculin increased in the Dex-treated group,and more spread but depolymerized actin fiber was seen in the TRPM7-siRNA transfected group.Compared with the normal control group,the fluorescence intensity of [Ca2×] i was weak in the Dex-treated group and TRPM7-siRNA transfected group.The relative expression levels of p-confilin protein was lower in the TRPM7-siRNA transfected group than that in the siRNA transfected group (0.317 ±0.031 vs.0.092±0.071) (t =5.030,P =0.007).Conclusions Dex induces the downregulation of TRPM7 expression in HTMs.The downregulation of TRPM7 probably participates in Dex-induced cytoskeletal remodeling by causing the depolymerization of actin cytoskeleton and reduction of [Ca2+] i in HTMs.