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Min Hyung Kang, Dong-Jin Oh, Douglas J Rhee, Glaucoma; Functional analysis of peptides from Secreted Protein, Acidic and Rich in Cysteine (SPARC).. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5687.
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SPARC and hevin (SPARC-like 1) have 66% homology of amino acid sequence. However, these two proteins have distinct properties in the human trabecular meshwork (TM) regarding their response to TGF-β2 1. It has been known that three peptides are released from SPARC by matrix metalloproteinase 3 (MMP3)2.We hypothesize that these peptides from SPARC will give a distinct role for SPARC compared with hevin and elucidate the regulatory element for the expression of extracellular matrix (ECM) proteins in the human TM.
SPARC peptides (SZ1, SZ2 and SZ3) have been chemically synthesized based on the amino acid sequences published by E. Sage2. Cultured TM cells were treated with these peptides in dose-dependent manner (100 µM, 10 µM, 1 µM and 0.1 µM). Western blot analysis was performed to investigate the effect of the peptides on SPARC and fibronectin, one of ECM proteins.
Western blot analysis showed that SZ1 and SZ2 had no effect on the expression of SPARC and fibronectinECM proteins in the cultured TM. However, SZ3 showed the negative regulation on the expression of fibronectinECM protein (IC50= 0.887 µM ±0.26, n=4) while no effect was shown on the expression of SPARC.
We found that one of SPARC peptides (SZ3) negatively regulated the expression of ECM proteins without affecting on the expression of SPARC in the cultured TM, which could provide the clue for the functional difference between SPARC and hevin.
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