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Kevin Wang, Ravi Metlapally, Christine Wildsoet; Identification of integrin receptor subunits in the guinea pig sclera. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3593.
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Treatment for myopia, the result of excessive elongation of the globe, has been directed mostly at the symptoms and not at the core issue of elongation. The ocular dimensional changes reflect increased scleral remodeling, which is also associated with biomechanical weakening of the sclera. As integrins have been linked to scleral remodeling previously, they represent potential targets for myopia treatments aiming to slow ocular elongation. As a first step, this study aimed to characterize the integrin subunits in the guinea pig sclera, a common myopia model.
Primers for α and β integrin subunits were designed using NCBI entries from a genome sequencing project, Primer3, and UCSC Genome Browser Bioinformatics. Total RNA was extracted from both intact scleral samples and fibroblasts cultured from guinea pig sclera. Reverse transcription was performed to produce cDNA and PCR used to amplify products of a predetermined size. Finally, PCR products were sequenced to confirm their identity.
PCR analysis of intact guinea pig scleral samples revealed twenty-four of the twenty-six known integrin subunits, corresponding to a possible twenty-two combinations of integrins, while only twenty-one of the twenty-six known subunits were detected in cultured scleral fibroblasts, allowing for nineteen potential integrin combinations. Specifically, scleral tissue expressed all known integrin alpha subunits except integrin αD and αE, which were also not expressed in scleral fibroblasts although expression of integrin αD and αE was confirmed in guinea pig liver. Integrins αL, αM, and αX were also not expressed in scleral fibroblasts. Both guinea pig scleral tissue and scleral fibroblasts expressed all known integrin beta subunits. All results were verified through sequencing.
While the above results are similar to those of a previous study in the tree shrew, another popular myopia model, guinea pig sclera expressed all known mammalian beta integrin subunits while tree shrew sclera did not express β2-, β3-, β6-, and β7-integrin subunits. However, alpha integrin subunits found in tree shrew sclera were also found in guinea pig sclera. Data provided from this study will help guide future studies directed at understanding the relationship between scleral integrins and myopia.
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