title: Transforming growth factor beta peptide antagonists and their conversion to partial agonists.
abstract: Transforming growth factor beta (TGF-beta) has been implicated in the pathogenesis of various human diseases. Synthetic TGF-beta antagonists therefore could have therapeutic utility. Here we show the development of such compounds. Three synthetic pentacosapeptides designated beta125-(41-65), beta225-(41-65), and beta325-(41-65), whose amino acid sequences correspond to the 41st to 65th amino acid residues of TGF-beta1, TGF-beta2, and TGF-beta3, respectively, inhibit the binding of 125I-labeled TGF-beta isoforms to TGF-beta receptors in mink lung epithelial cells with IC50 of approximately 0.06-2 microM. beta125-(41-65) blocks TGF-beta1-induced growth inhibition and TGF-beta1-induced plasminogen activator inhibitor-1 expression in these cells. The variants designated beta125-(41-65)W52A/D55A and beta325-(41-65)R52A/D55A, in which both Trp52/Arg52 and Asp55 are replaced by alanine residues, do not have TGF-beta antagonist activity. Multiple conjugation of beta125-(41-65) to carrier proteins enhances its antagonist activity but also confers partial agonist activity as measured by DNA synthesis inhibition. These results suggest that the (W/R)XXD motif is important for the activities of these TGF-beta peptide antagonists and that this motif may be the active site sequence of TGF-beta.
authors.affiliation: Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Huang
authors.forename: Q
authors.initials: Q
authors.lastname: Liu
authors.forename: F E
authors.initials: FE
authors.lastname: Johnson
authors.forename: Y
authors.initials: Y
authors.lastname: Konish
authors.forename: J S
authors.initials: JS
authors.lastname: Huang
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis; D004848:Epithelium; D014644:Genetic Variation; D006801:Humans; D007700:Kinetics; D008168:Lung; D008907:Mink; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000494:pharmacology*; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis*; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000819:agonists / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: D010446:Peptide Fragments; D017395:Plasminogen Activator Inhibitor 1; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D004247:DNA