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AY Rose, JM Bradley, V Vittal, TS Acott, MJ Kelley; Integrin Responses to Mechanical Stretching in Trabecular Meshwork Cells . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1045.
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Purpose: Intraocular pressure (IOP) homeostasis may involve changes in trabecular matrix metalloproteinase (MMP) activity triggered in response to mechanical stretching. Integrins, a family of extracellular matrix cell surface receptors, are often involved in signaling of this type. Thus, studies were conducted to evaluate changes in trabecular integrins in response to mechanical stretching. Methods: Porcine TM cells were grown to confluence on membranes in tissue culture. Serum-free trabecular cells were then subjected to mechanical stretching as a model for elevated IOP. Changes were evaluated by Western immunoblotting, microarray, or confocal microscopy. Results: ß1-, ß3- and αv-integrin increased in cells subjected to mechanical stretch at 24, 48, and 72 hrs by Western immunoblotting. Similar increases at the same times were noted in membrane-type-1 matrix metalloproteinase (MT-1-MMP), the integrin-associated protein, CD47, and paxillin. CD47, αv, and ß3-integrin mRNA increased initially and then decreased on microarrays following stretch. Comparison of ß3-integrin, CD 47, and paxillin in stretched and control cells by confocal microscopy showed differences in patterning, localization, and/or increasing amount with mechanical stretch at times ranging from 1 to 24 hours. Conclusion: Three types of temporal changes were noted in response to mechanical stretch. Confocal microscopy showed early, immediate changes in localization and patterning of ß3-integrin, CD 47, and paxillin. CD47 also showed both a more sustained mRNA intermediate-term change and an long-term increase in protein at 24-72 hrs. Similar long-term increases were seen in ß1-, ß3-, αv-integrin, paxillin, and MT-1-MMP. These changes may reflect adjustment mechanisms important in maintaining IOP homeostasis.
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