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Linda Musil; Upregulation of TGFβ signaling in lens cells by fibronectin: implications for PCO. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1604.
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© ARVO (1962-2015); The Authors (2016-present)
After cataract surgery, surviving lens epithelial cells are exposed to increased levels of fibronectin. Because extracellular matrix can profoundly affect growth factor signaling, we asked if fibronectin influences lens cell fate using an established serum-free primary lens epithelial cell culture system (DCDMLs).
DCDMLs were plated on laminin or fibronectin and then cultured for up to 7 days without added TGFβ. Western blotting and metabolic labeling were used to quantitate expression of lens fiber cell and myofibroblast markers. Activation of canonical Smad3 signaling was assessed by anti-phosphoSmad3 Western blotting and by transient transfection of the SBE4-luciferase transcriptional reporter.
Culturing subconfluent DCDMLs with plasma-derived fibronectin, either coating the tissue culture dish well or added to the culture medium, increased canonical TGFβ signaling relative to cells plated on laminin. Fibronectin-exposed cultures also showed increased differentiation of lens epithelial cells into both of the cell types responsible for clinically deleterious posterior capsule opacification after cataract surgery, namely myofibroblasts and immature lens fiber cells. Blocking TGFβ receptor activation with SB-431542 inhibited these processes, indicating an essential role for TGFβ signaling. Higher levels of TGFβ activity were recovered from the conditioned medium of DCDMLs grown on fibronectin than from cultures plated on laminin. This increase was due primarily to enhanced activation, instead of greater expression, of endogenous TGFβ.
Growing DCDMLs in the presence of fibronectin phenocopies the effects of adding active TGFβ to laminin-plated cells. These results demonstrate how the TGFβ/fibronectin axis can profoundly affect lens cell fate even in the absence of exogenous TGFβ. Because of the persistence of fibronectin and TGFβ signaling after cataract surgery, this axis represents a novel target for therapies to prevent the common but currently therapeutically intractable complication of late-onset posterior capsule opacification.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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