Rho plays a key role in TGF-beta1-induced cytoskeletal rearrangement in human retinal pigment epithelium.
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.
Lee
Jungeun
J
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.
Ko
Meekyung
M
Joo
Choun-Ki
CK
D051339:Actin Depolymerizing Factors / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D048430:Cell Shape; D003599:Cytoskeleton / Q000378:metabolism*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D054461:Lim Kinases / Q000378:metabolism; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051899:Smad2 Protein / Q000378:metabolism; D051900:Smad3 Protein / Q000378:metabolism; D022502:Stress Fibers / Q000378:metabolism / Q000648:ultrastructure; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*; D018630:Vitreoretinopathy, Proliferative / Q000378:metabolism / Q000473:pathology; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
C541116:ACTA2 protein, human; D051339:Actin Depolymerizing Factors; D000199:Actins; D004791:Enzyme Inhibitors; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; D051899:Smad2 Protein; D051900:Smad3 Protein; D053773:Transforming Growth Factor beta1; C515892:LIMK1 protein, human; D054461:Lim Kinases; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein