The Role of Vimentin in Human Corneal Fibroblast Spreading and Myofibroblast Transformation

Vimentin has been reported to play diverse roles in cell processes such as spreading, migration, and cell-matrix adhesion. Here, we use vimentin knock out cells (Vim KO) to assess how vimentin impacts cell spreading, morphology, and myofibroblast transformation of human corneal fibro-blasts. Overall, loss of vimentin did not significantly impact corneal fibroblast spreading, as indicated by Vim KO morphology and mechanical activity (traction force). However, we found that Vim KO cells had reduced elongation in response to PDGF as compared to controls. Furthermore, absence of vimentin did not completely block TGFβ induced myofibroblast transformation, since αSMA protein expression was detected in Vim KO cells. Nonetheless, the degree of transformation and amount of αSMA protein was reduced as compared to control cells. Proteomics showed that Vim KO cells cultured in TGFβ had a similar pattern of protein expression as controls. One exception included periostin, an ECM protein associated with wound healing and fibrosis in other cell types, which was highly expressed only in Vim KO cells. We also demonstrate for the first time that LRRC15, a protein previously associated with myofibroblast transformation of cancer-associated fibroblasts, is also expressed by corneal myofibroblasts. Overall, our data shows that vimentin has a limited, yet measurable impact on corneal fibroblast spreading and myofibroblast transformation. We also identified novel proteins that may regulate corneal myofibroblast transformation in the presence and/or absence of vimentin.