Hyperosmotic stress induces ATP release and changes in P2X7 receptor levels in human corneal and conjunctival epithelial cells
Hyperosmotic stress induces ATP release and changes in P2X7 receptor levels in human corneal and conjunctival epithelial cells
复制标题
DOI：
10.1007/s11302-017-9556-5
复制
发表时间：
2017-06-01
影响因子：
3.5
通讯作者：
Pintor, Jesus
中科院分区：
文献类型：
--
作者：
Guzman-Aranguez, Ana;Perez de Lara, Maria J.;Pintor, Jesus
泪液高渗是干眼症的关键事件。在这项工作中，我们分析了高渗刺激是否会导致眼表ATP的释放。此外，由于细胞外的ATP可以激活P2X7受体，本研究还观察了高渗处理后细胞内P2X7蛋白水平的变化及其在病理过程中的作用。高效液相色谱分析显示，与对照组相比，暴露于高渗刺激下的人角膜和结膜上皮细胞以及干眼症患者的ATP水平显著增加。细胞活力在高渗处理后显著降低，表明ATP释放的增加主要是由于细胞的裂解/死亡。此外，在两种细胞系中都发现了囊泡核苷酸转运体，并在高渗介质中上调了它们的蛋白表达。在两种细胞系中都发现了P2X7受体的截短形式和全长形式，用P2X7的特异性拮抗剂和激动剂进行的实验表明，该受体不介导高渗应激诱导的细胞死亡。综上所述，高渗应激诱导了ATP的释放。细胞外ATP可激活P2X7受体，导致许多细胞/组织的细胞毒作用，但在人的角膜和结膜上皮细胞中不存在这种作用。在这些细胞中，P2X7受体的截短形式和全长形式的存在共同阻碍了眼睛表面的P2X7凋亡行为。
Tear hyperosmolarity is a key event in dry eye. In this work, we analyzed whether hyperosmolar challenge induces ATP release on the ocular surface. Moreover, as extracellular ATP can activate P2X7 receptor, the changes in P2X7 protein levels and its involvement in pathological process triggered by hypertonic treatment were also examined. High-performance liquid chromatography analysis revealed that ATP levels significantly increased in human corneal and conjunctival epithelial cells exposed to hyperosmotic challenge as well as in dry eye patients as compared to control subjects. A significant reduction in cell viability was detected after hyperosmolar treatment, indicating that the rise in ATP release was mainly due to cell lysis/death. Additionally, vesicular nucleotide transporter was identified in both cell lines and their protein expression was upregulated in hypertonic media. P2X7 receptor truncated form together with the full-length form was identified in both cell lines, and experiments using specific antagonist and agonist for P2X7 indicated that this receptor did not mediate cell death induced by hyperosmolar stress. In conclusion, hyperosmotic stress induces ATP release. Extracellular ATP can activate P2X7 receptor leading to cytotoxicity in many cells/tissues; however, this does not occur in human corneal and conjunctival epithelial cells. In these cells, the presence of P2X7 receptor truncated form together with the full-length form hinders a P2X7 apoptotic behavior on the ocular surface.