Corneal antifibrotic switch identified in genetic and pharmacological deficiency of vimentin |
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Authors: | Bargagna-Mohan Paola Paranthan Riya R Hamza Adel Zhan Chang-Guo Lee Do-Min Kim Kyung Bo Lau Daniel L Srinivasan Cidambi Nakayama Keiko Nakayama Keiichi I Herrmann Harald Mohan Royce |
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Affiliation: | Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut 06030, USA. |
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Abstract: | The type III intermediate filaments (IFs) are essential cytoskeletal elements of mechanosignal transduction and serve critical roles in tissue repair. Mice genetically deficient for the IF protein vimentin (Vim(-/-)) have impaired wound healing from deficits in myofibroblast development. We report a surprising finding made in Vim(-/-) mice that corneas are protected from fibrosis and instead promote regenerative healing after traumatic alkali injury. This reparative phenotype in Vim(-/-) corneas is strikingly recapitulated by the pharmacological agent withaferin A (WFA), a small molecule that binds to vimentin and down-regulates its injury-induced expression. Attenuation of corneal fibrosis by WFA is mediated by down-regulation of ubiquitin-conjugating E3 ligase Skp2 and up-regulation of cyclin-dependent kinase inhibitors p27(Kip1) and p21(Cip1). In cell culture models, WFA exerts G(2)/M cell cycle arrest in a p27(Kip1)- and Skp2-dependent manner. Finally, by developing a highly sensitive imaging method to measure corneal opacity, we identify a novel role for desmin overexpression in corneal haze. We demonstrate that desmin down-regulation by WFA via targeting the conserved WFA-ligand binding site shared among type III IFs promotes further improvement of corneal transparency without affecting cyclin-dependent kinase inhibitor levels in Vim(-/-) mice. This dissociates a direct role for desmin in corneal cell proliferation. Taken together, our findings illuminate a previously unappreciated pathogenic role for type III IF overexpression in corneal fibrotic conditions and also validate WFA as a powerful drug lead toward anti-fibrosis therapeutic development. |
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Keywords: | Cell Cycle Cytoskeleton Drug Discovery Fibrosis Pharmacogenetics Desmin Skp2 Tissue Repair Vimentin Withaferin A |
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