Epithelial-Mesenchymal Transition and Proliferation of Retinal Pigment Epithelial Cells Initiated upon Loss of Cell-Cell Contact
Epithelial-Mesenchymal Transition and Proliferation of Retinal Pigment Epithelial Cells Initiated upon Loss of Cell-Cell Contact
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DOI：
10.1167/iovs.09-4725
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发表时间：
2010-05-01
影响因子：
4.4
通讯作者：
Kaplan, Henry J.
中科院分区：
文献类型：
--
作者：
Tamiya, Shigeo;Liu, LanHsin;Kaplan, Henry J.
目的。眼纤维化并发症中上皮-间质转化（EMT）的分子机制尚不明确。研究了细胞间接触在调节EMT和视网膜色素上皮细胞（RPE）增殖中的作用。将猪RPE细胞分离成薄片，体外培养于透镜囊上。显微镜下观察细胞形态。Western blot和免疫染色法观察蛋白表达情况。分别用BrdU掺入和吞噬实验评估细胞增殖和RPE功能。每张薄片中心的RPE细胞保持了细胞间的接触，并保持了分化的表型。钙粘蛋白在这些细胞中的功能破坏导致细胞间接触的丧失，同时诱导间充质标记蛋白的表达和细胞增殖。薄片边缘的RPE细胞迁移离开薄片，进行EMT，并开始增殖，这伴随着cadherin从P-cadherin到N-cadherin的表达转换。尽管tgf - β被认为是EMT的经典诱导剂，但它无法在维持细胞间接触的RPE细胞中启动EMT。然而，tgf - β在已经接受emt的细胞中诱导α - sma阳性肌成纤维细胞的变化。在RPE细胞中，EMT和增殖的开始是由细胞间接触的丧失引起的。tgf - β不能启动EMT或维持细胞间接触的RPE细胞的增殖，但似乎在EMT下游诱导向肌成纤维细胞表型（与纤维化并发症的发生有关的表型）的转变中起重要的次要作用。（中国眼科杂志，2010;51:2755-2763）DOI: 10.1167/iovs.09-4725
PURPOSE. Molecular mechanisms that initiate epithelial-mesenchymal transition (EMT) involved in ocular fibrotic complications remain elusive. Studies were conducted to examine the role of cell-cell contact in regulating EMT and proliferation of retinal pigment epithelial (RPE) cells.METHODS. Porcine RPE cells were isolated as sheets and cultured in vitro on lens capsules. Cell morphology was examined by microscopy. Western blot analysis and immunostaining were used to follow protein expression. Cell proliferation and RPE function were assessed by BrdU incorporation and phagocytosis assay, respectively.RESULTS. RPE cells in the center of each sheet maintained cell-cell contacts and retained a differentiated phenotype. Disruption of cadherin function in these cells resulted in the loss of cell-cell contact and the concomitant induction of mesenchymal marker protein expression and cell proliferation. RPE cells at the edge of the sheet migrated away from the sheet, underwent EMT, and initiated proliferation, which was accompanied by a switch in cadherin expression from P-cadherin to N-cadherin. Although TGF-beta is thought to be a classic inducer of EMT, it was unable to initiate EMT in RPE cells maintaining cell-cell contact. However, change to alpha-SMA-positive myofibroblasts was induced by TGF-beta in cells that had already undergone EMT.CONCLUSIONS. EMT and the onset of proliferation in RPE cells is initiated by loss of cell-cell contact. TGF-beta cannot initiate EMT or the proliferation of RPE cells maintaining cell-cell contact but appears to play an important secondary role downstream of EMT in inducing transition to a myofibroblast phenotype-a phenotype linked to the development of fibrotic complications. (Invest Ophthalmol Vis Sci. 2010; 51: 2755-2763) DOI: 10.1167/iovs.09-4725