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H. Mishima, III, M. Maeda, K. Abe, Y. Simomura; The Interaction Between SPARC Peptide (TCDL) and TGF-Beta on Corneal Fibroblasts. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1494.
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SPARC (secreted protein which is acidic rich in cysteine) and TGF-beta are thought to contribute to corneal stromal wound healing. We previously reported that SPRAC-derived peptide, corresponding to domain IV of SPARC, modulated the collagen contraction by corneal fibroblasts. In the present study, to understand active site of SPARC in detail, we investigated the interaction between SPARC peptide and TGF-beta on corneal fibroblasts in vitro.
We synthesized peptides that consist of four to eight amino acids from 245th amino acid of SPARC (TCDL, TCDLDN, TCDLDNDK). Rabbit corneal fibroblasts were cultured in a collagen gel with peptides and/or TGF-beta. The diameter of the gel was measured after 5 days’ cultivation. The cells were cultured on collagen matrix with TCDL and/or TGF-beta. The .expression of α-smooth muscle actin (αSMA) and the intracellular localization of smad2/3 were observed immunocytochemically.
Either of the synthetic peptides (0.3mM), TCDL, TCDLDN, TCDLDNDK, inhibited the collagen contraction by corneal fibroblasts. TGF-beta stimulated the collagen contraction by the cells. When the cells were cultured with TCDL and TGF-beta, the stimulatory effect of TGF-bet on the collagen gel contraction by the cell was significantly inhibited. When corneal fibroblasts were cultured with TGF-beta, the proportion of the cells which expressed αSMA increased significantly. However, when TCDL was added simultaneously, the population of αSMA(+) cells decreased. Smad2/3 was stained in cytoplasma of corneal fibroblasts in the control group. When TGF-beta was added to the medium, smad2/3 was accumulated to the nucleolus. The presence of TCDL did not inhibited the accumulation of smad2/3 initiated by TGF-beta.
These findings suggested that TCDL could regulate the action of TGF-beta on corneal fibroblasts. It was also suggested that inhibitory effect of TCDL on TGF-beta was not depended on smad2/3.
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