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J. Amaral, B. Burkam, P. Becerra; Antiangiogenic Effects of PEDF Peptide Fragments and Cleaved PEDF . Invest. Ophthalmol. Vis. Sci. 2005;46(13):453.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate the antiangiogenic effects of PEDF peptide fragments for studies on structure–function relationships of PEDF. Methods: Human recombinant PEDF was cleaved at its homologous reactive serpin loop by control proteolysis with chymotrypsin. SDS–polyacrylamide gel electrophoresis followed by Coommassie blue staining confirmed the production of the cleaved PEDF of 46–kDa protein. PEDF peptides 34–mer and 44–mer were designed from the human PEDF sequence 44–77 and 78–121 amino acid positions, respectively. Human angiostatin® K1–5 was used as a positive control and ovalbumin as negative control. The antiangiogenic effects were tested in tube formation, ex–vivo chick aortic vessel sprouting assays, and in laser–induced choroidal neovascularization (CNV) rat models. Results:Full length PEDF was antiangiogenic when tested at 0.1–100 nM and was comparable to that of angiostatin in in–vitro assays. In animal models, subconjunctival injections of both PEDF and angiostatin reduced laser–induced CNV. The PEDF cleaved at its serpin exposed loop retained its antiangiogenic activity. At concentrations between 1 nM and 10 nM the 34–mer fragment of PEDF induced less vessel sprouting than the 44–mer. At similar concentrations (10nM) ovalbumin showed no antiangiogenic effects. At concentrations of 100 nM, both peptides had very similar effects in vessel sprouting inhibition. Conclusions: The serpin exposed loop, the serpin structural determinant of serine protease inhibition by serpins, was dispensable for the antiangiogenic activity of PEDF. The 34–mer peptide region of human PEDF retained the antiangiogenic properties of the full length PEDF polypeptide. These results suggest that the use of small fragments of PEDF might be a feasible approach for antiangiogenic therapy.
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