维生素D受体对低氧下结肠细胞屏障蛋白的作用

目的 探究低氧环境对结肠细胞DLD-1屏障蛋白影响及补偿机制。方法 将DLD-1分别给予低氧(l% O₂)、维生素D(100 nmol/L)及低氧联合维生素D处理48 h。Western blot法检测各组细胞中紧密连接蛋白封闭小带-1(ZO-1)、闭锁蛋白、Claudin-1和上皮细胞钙黏蛋白及维生素D受体(VDR)的表达情况。采用慢病毒包装的方法建立DLD-1的VDR稳转敲降细胞系及对照,给予低氧处理后,检测上述蛋白的表达情况。结果 与对照组相比,DLD-1低氧处理48 h后紧密连接结构蛋白闭锁蛋白、Claudin-1及VDR表达均增加(P均<0.001),低氧+维生素D联合处理组较单独维生素D处理组除闭锁蛋白、Claudin-1及VDR表达增加外,ZO-1及上皮细胞钙黏蛋白表达也明显增加(P均<0.001)。VDR敲降细胞系低氧处理后,ZO-1(P<0.001)、闭锁蛋白(P<0.05)、Claudin-1(P<0.01)及上皮细胞钙黏蛋白(P<0.001)表达均显著降低。结论 VDR对于低氧状态下结肠细胞系DLD-1肠上皮屏障蛋白表达有调节作用,提示VDR通路可能为低氧环境下保护肠黏膜屏障的另一重要机制。

Effects of Vitamin D Receptor on Mucosal Barrier Proteins in Colon Cells under Hypoxic Environment

Objective To investigate the expressions of mucosal barrier proteins in colon cell line DLD-1 under hypoxic environment in vitro and its mechanism. Methods After DLD-1 cells were treated separately with hypoxia(l% O₂),vitamin D(100 nmol/L),or vitamin D plus hypoxia for 48 hours,the expressions of vitamin D receptor(VDR),tight junction proteins zonula occludens-1(ZO-1),occludin,Claudin-1,and adherent junction protein(E-cadherin)were determined by Western blot.Stable VDR knock-down(Sh-VDR)DLD-1 cell line and control DLD-1 cell line were established by lentivirus package technology and the protein expressions after hypoxia treatment were detected. Results Compared with control group,the expressions of occludin,Claudin-1,and VDR increased significantly after hypoxia treatment(all P<0.001).In addition to the protein expressions of occludin,Claudin-1 and VDR,the expressions of ZO-1 and E-cadherin were also obviously higher in vitamin D plus hypoxia group than in single vitamin D treatment group(all P<0.001).After hypoxia treatment,Sh-VDR cell line showed significantly decreased expressions of ZO-1(P<0.001),occludin(P<0.05),Claudin-1(P<0.01)and E-cadherin(P<0.001)when compared with untreated Sh-VDR cell line. Conclusion VDR acts as a regulator for the expressions of intestinal mucosal barrier proteins under hypoxia environment in DLD-1 colon cell line,indicating that VDR pathway may be another important protective mechanism for gut barrier in low-oxygen environment.