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C.R. Hann, D.H. Johnson; Focal Adhesions Are Most Prevalent in Schlemm’s Canal and Juxtacanalicular Regions of the Trabecular Meshwork . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3699.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Focal adhesion proteins can change in response to biomechanical forces such as shear stress and hydrostatic pressure. The purpose of our study was to examine the distribution and relative density of three focal adhesion proteins – paxillin, vinculin and tensin in the trabecular meshwork and to determine whether differences occurred in high stress regions (SC, JCT). The second purpose was to examine the variability of these proteins around the circumference of the eye. Methods: Four normal human eyes were immersion fixed and divided into quadrants. Wedges, 0.5mm thick, from two quadrants 180° apart were immunolabeled for paxillin, vinculin or tensin. Actin and nuclei were also stained in each wedge. Confocal microscopy was used to view 40 sections (0.5µm) from each wedge. Circumferential varibility was assessed from four quadrants of one eye for each focal adhesion proteins. The distribution and density were qualitatively evaluated. Results: In SC cells, paxillin was the most common focal adhesion protein, followed by vinculin and tensin. Paxillin was abundantly present occupying prominent cytoplasmic areas in the base and lateral regions in almost every SC cell. In contrast, vinculin was found in one half to two thirds of SC cells examined. It was present in discrete spots. Tensin was present infrequently in isolated SC cells. In the JCT and corneoscleral regions paxillin and vinculin were found less commonly, being present only in scattered cells. Tensin was less common in these regions. Areas of co–localization of paxillin or vinculin with actin were frequently observed in SC cells at the base and in the lateral regions of the cells. Circumferential distribution of paxillin and vinculin was observed. Tensin distribution was patchy and was infrequently found. Conclusions: Focal adhesions were most prevalent in SC cells. They were also found in cells of the JCT cells and CS regions. Paxillin was the most common and prominent focal adhesion protein followed by vinculin and tensin. Both paxillin and vinculin were observed to co–localize with actin in the base and lateral regions of the SC cells. Future work will include comparison of focal adhesions in normal and glaucomatous eyes.
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