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N. Taenaka, T. Hibino, M. Fukuda, H. Mishima, Y. Shimomura; Tissue Transglutaminase Modulates the Proliferation and Attachment of Keratocytes . Invest. Ophthalmol. Vis. Sci. 2003;44(13):881.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Tissue transglutaminase(tTG) is a calcium-dependent enzyme that is present in many different cell types and tissues. The enzyme plays a role in apoptosis, cell adhesion, and cell proliferation, and interaction between the cell and its ECM via the cross-linking of proteins. However, the influence of tTG of keratocytes has not been well understood yet. In the present study we investigated the expression of tTG in keratocytes and the effect of tTG for the proliferation and the attachment of keratocytes. Methods: The expression of tTG in human keratocytes was investigated immunohistochemically. Subconfluent human keratocytes were seeded on 96-well culture plates and cultured in serum-free MEM containing the various concentrations of a TG inhibitor, cystamine (50-200µM) and a TG production stimulator, sodium butyrate (NaB) (0.01-1mM) with or without TGF-ß(1ng/ml) or EGF(10 ng/ml) for 24 hours. The cell numbers were measured by BrdU incorporation. In other experiments, keratocytes were seeded on fibronectin-coated or BSA-coated plates and were incubated with tTG (0.01-0.1U/ml) with or without RGD peptide or RGE peptide(200-400µM) for 90 minites. The numbers of attached cells were measured by MTT assay. Results: tTG was observed in the cytoplasm of human keratocytes. Cystamin promoted the proliferation of keratocytes in a dose dependent manner. TGF-ß or EGF stimulated the proliferation of keratocytes. Cystamin also stimulated the action of TGF-ß or EGF on keratocytes. On the other hand, NaB inhibited that of keratocytes. tTG enhanced the cell attachment of keratocytes in a dose dependent manner. The tTG-induced cell attachment was inhibited by not RGE peptide, but RGD peptide both on BSA-coated plates and fibronectin coated plates. Conclusions: tTG was expressed in human keratocytes. These findings suggested that tTG inhibited the proliferation of keratocytes and promoted the RGD dependent cell attachment.
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