title: Identification of the thiol isomerase-binding peptide, mastoparan, as a novel inhibitor of shear-induced transforming growth factor β1 (TGF-β1) activation.
abstract: TGF-β1 is a disulfide-bonded homodimeric protein produced by platelets and other cells that plays a role in many physiologic and pathologic processes. TGF-β1 is secreted as an inactive large latent complex (LLC) comprised of TGF-β1, latency-associated peptide, and latent TGF-β binding protein 1. We previously demonstrated that shear force can activate LLC and that thiol-disulfide exchange contributes to the process. We have now investigated the role of thiol isomerases in the activation of LLC in platelet releasates (PR) and recombinant LLC. The wasp venom peptide mastoparan, which inhibits the chaperone activity of PDI, inhibited stirring- and shear-induced activation of latent TGF-β1 by 90 and 75% respectively. To identify the proteins that bind to mastoparan either directly or indirectly, PR were chromatographed on a mastoparan affinity column. Latent TGF-β binding protein 1, latency-associated peptide, TGF-β1, clusterin, von Willebrand factor, multimerin-1, protein disulfide isomerase (PDI), ERp5, ERp57, and ERp72 eluted specifically from the column. Anti-PDI RL90 attenuated the inhibitory effect of mastoparan on LLC activation. Furthermore, reduced PDI inhibited activation of PR LLC, whereas oxidized PDI had no effect. We conclude that thiol isomerases and thiol-disulfide exchange contribute to TGF-β1 activation and identify a number of molecules that may participate in the process.
authors: Laboratory of Blood and Vascular Biology, The Rockefeller University, New York, New York 10065, USA.
authors: Teresa M
authors: TM
authors: Brophy
authors: Barry S
authors: BS
authors: Coller
authors: Jasimuddin
authors: J
authors: Ahamed
mesh_terms: D001792:Blood Platelets / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism; D002460:Cell Line; D051152:Clusterin / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D005260:Female; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D053779:Latent TGF-beta Binding Proteins / Q000378:metabolism*; D008297:Male; D010455:Peptides / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D019704:Protein Disulfide-Isomerases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D014862:Wasp Venoms / Q000494:pharmacology*; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D001798:Blood Proteins; C495242:CLU protein, human; D051152:Clusterin; D004220:Disulfides; D036341:Intercellular Signaling Peptides and Proteins; D053779:Latent TGF-beta Binding Proteins; D010455:Peptides; D053773:Transforming Growth Factor beta1; D014862:Wasp Venoms; C069282:multimerin; D014841:von Willebrand Factor; C037500:mastoparan; D019704:Protein Disulfide-Isomerases