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M. A. Stepp, S. Pal-Ghosh, G. Tadvalkar, W. P. Daley, M. Larsen; Corneal Stromal Cells Express vβ1 Integrin and Localize It to Focal and Fibrillar Adhesions. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3833.
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© ARVO (1962-2015); The Authors (2016-present)
Corneal Stroma Cells (CSCs) were isolated from wt and mice lacking sdc-1 to determine their integrin expression profile and to correlate it with their cell migration properties and their ability to assemble a fibronectin matrix.
Corneas from 8 week old mice were digested with collagenase, digests filtered to separate cells from stromal components, and cells placed in culture and used within 3-4 passages. Cell migration rates using time-lapse microscopy. Integrin expression and localization were assessed using immunoblots and immunofluorescence, and fibronectin assembly into fibrils was assessed by isolation of deoxycholate soluble and insoluble protein fractions from cells. Extracts were then subjected to immunoblotting.
Sdc-1 null CSCs migrate significantly faster than wt CSCs. The expression of both total β1 and αv integrins is 2.0 fold greater in the sdc-1 null stromal cells; α5 integrin is slightly but significantly enhanced in expression in the sdc-1 null cells whereas α7 integrin is downregulated by 66%. β3 and β5 integrin levels were similar in wt and sdc1 null CSCs. Immunofluorescence studies showed that whereas α5 and β3 rarely localized to focal adhesions, αv and β1 integrin co-localized to focal adhesions in both wt and sdc1 null CSCs. The focal adhesions seen in sdc1 null cells were larger than those seen in wt cells. The presence of elevated levels of αvβ1 within focal adhesions on the surface of sdc1 null CSCs was found to correlate with reduced fibonectin fibrillogenesis.
These studies show that both wt and sdc1 null CSCs express αvβ1 at high levels. The impact of elevated expression of αvβ1 on the regulation of ECM synthesis and assembly by these cells is not clear but these results suggest that proteins that regulate β1 but not β3 or β5 integrins are more relevant to ECM assembly in corneal stromal cells than in typical fibroblasts.
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