Lee Jungeun, Ko Meekyung, Joo Choun-Ki
Laboratory of Ophthalmology and Visual Science, Catholic Research Institutes of Medical Sciences, Korean Eye Tissue and Gene Bank Related to Blindness, College of Medicine, The Catholic University of Korea, Seoul, Korea.
J Cell Physiol. 2008 Aug;216(2):520-6. doi: 10.1002/jcp.21424.
Proliferative vitroretinopathy (PVR) is caused by retinal pigment epithelial (RPE) cell proliferation and transformation into fibrotic cells that produce extracellular matrix (ECM) components. Transforming growth factor beta1 (TGF-beta1) is known to play an important role in PVR pathogenesis. To determine how TGF-beta1 mediates the pathogenic changes in RPE cells, we characterized the effects of TGF-beta1 on the morphology, ECM accumulation, and stress fiber formation of ARPE-19 cells, a human RPE cell line. We then elucidated the signaling pathways that mediate these effects. Serum-starved ARPE-19 cells were incubated with 10 ng/ml TGF-beta1 and their morphological changes were examined by phase-contrast microscopy. Actin reorganization was examined by immunochemistry and confocal microscopy. Protein phosphorylation was analyzed by Western blot analysis. TGF-beta1 treatment induced cytoskeleton reorganization, alpha-SMA expression, increased the phosphorylation of ERK, Smad2/3, and AKT, and activated RhoA and Rac1. Cytoskeletal rearrangement was prevented by pretreatment with a Rho inhibitor and by expression of a dominant negative form of Rho. TGF-beta1 also increased LIM kinase and cofilin phosphorylation and the Rho inhibitor blocked this effect. We propose that TGF-beta1 induces human RPE cells to undergo cytoskeletal actin rearrangement via Rho GTPase-dependent pathways that modulate LIM kinase and cofilin activity. This inhibits actin depolymerization and induces the cytoskeletal rearrangements in RPE cells that result in the characteristic features of PVR.
增殖性玻璃体视网膜病变（PVR）是由视网膜色素上皮（RPE）细胞增殖并转化为产生细胞外基质（ECM）成分的纤维化细胞引起的。已知转化生长因子β1（TGF-β1）在PVR发病机制中起重要作用。为了确定TGF-β1如何介导RPE细胞的致病变化，我们对TGF-β1对人RPE细胞系ARPE-19细胞的形态、ECM积累和应力纤维形成的影响进行了表征。然后我们阐明了介导这些影响的信号通路。将血清饥饿的ARPE-19细胞与10 ng/ml TGF-β1孵育，通过相差显微镜检查其形态变化。通过免疫化学和共聚焦显微镜检查肌动蛋白重组。通过蛋白质印迹分析分析蛋白质磷酸化。TGF-β1处理诱导细胞骨架重组、α-SMA表达，增加ERK、Smad2/3和AKT的磷酸化，并激活RhoA和Rac1。用Rho抑制剂预处理和表达Rho的显性负性形式可防止细胞骨架重排。TGF-β1还增加了LIM激酶和丝切蛋白的磷酸化，Rho抑制剂阻断了这种作用。我们提出，TGF-β1通过调节LIM激酶和丝切蛋白活性的Rho GTPase依赖性途径诱导人RPE细胞发生细胞骨架肌动蛋白重排。这抑制了肌动蛋白解聚，并诱导RPE细胞中的细胞骨架重排，从而导致PVR的特征性表现。
