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A Hutcheon, XQ Guo, JD Zieske; Translocation Of The Smad Proteins During Corneal Epithelial Wound Repair . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4199.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: We have previously reported that both TGFßR-I and -II were upregulated in corneal epithelium after wounding, and that TGFßR-II was specifically upregulated in corneal epithelial cells migrating to cover the wound. This suggests that TGF-ß signaling is present at higher levels in the cells migrating to cover the wound than in cells distal to the wound. To test this hypothesis, we examined the localization of Smads 2, 3, 4 and 7. These proteins are involved in TGF-ß signaling and translocate to the nucleus following receptor activation. Methods: Three-mm superficial keratectomy wounds were made in Sprague-Dawley rats, and allowed to heal 4, 8, 16, 24 and 48 hours. The unwounded contralateral eyes served as controls. The rats were sacrificed, corneas excised, and cryostat sections prepared. Smads 2, 3, 4 and 7 localization was observed using indirect immunofluorescence microscopy. The wound site was identified using anti-laminin. Specificity of antibodies was verified through western blotting. Results: Smads 2, 3, and 4 were localized in the cytoplasm of unwounded corneal epithelium. Upon wounding, both Smads 2 and 4 translocated into the nucleus in the basal cells of the migrating corneal epithelium. Smad 3 localization did not appear to change; whereas, Smad 7 did not appear to be present in corneal epithelium. Western blotting confirmed that Smads 2, 3 and 4 were present in corneal epithelium and Smad 7 was not. Conclusions: The finding that Smads 2 and 4 translocate to the nucleus of the epithelial basal cells migrating over the wound area, confirms our hypothesis that TGF-ß signaling is preferentially confined to the migrating cells.
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