title: Grafting of thrombopoietin-mimetic peptides into cystine knot miniproteins yields high-affinity thrombopoietin antagonists and agonists.
abstract: Thrombopoietin is the primary regulator of platelet production. We exploited two naturally occurring miniproteins of the inhibitor cystine knot family as stable and rigid scaffolds for the incorporation of peptide sequences that have been shown to act as high-affinity thrombopoietin antagonists. Several miniproteins that antagonistically block thrombopoietin-mediated receptor activation were identified using a microscale reporter assay. Covalent miniprotein dimerization yielded potent bivalent c-Mpl receptor agonists with EC(50) values in the low nanomolar or picomolar range. One selected miniprotein-derived thrombopoietin agonist was almost as active as natural thrombopoietin with regard to stimulation of megakaryocyte colony formation from human bone marrow mononuclear cells, and elicited doubling of platelet counts in mice. Our data suggest that dimeric cystine knot miniproteins have considerable potential for the future development of small and stable receptor agonists. This approach may provide a promising strategy for pharmaceutical interference with other receptors activated by ligand-induced dimerization.
authors.affiliation: University of Jena Medical School, Institute of Biochemistry, Jena, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Krause
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Schmoldt
authors.forename: Alexander
authors.initials: A
authors.lastname: Wentzel
authors.forename: Matthias
authors.initials: M
authors.lastname: Ballmaier
authors.forename: Karlheinz
authors.initials: K
authors.lastname: Friedrich
authors.forename: Harald
authors.initials: H
authors.lastname: Kolmar
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism; D002478:Cells, Cultured; D047168:Cystine Knot Motifs; D019281:Dimerization; D006801:Humans; D008533:Megakaryocytes / Q000166:cytology / Q000378:metabolism; D051379:Mice; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology*; D053628:Receptors, Thrombopoietin / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013926:Thrombopoietin / Q000819:agonists* / Q000037:antagonists & inhibitors*; D014162:Transfection
chemical_list: D010455:Peptides; D053628:Receptors, Thrombopoietin; D011993:Recombinant Fusion Proteins; C515728:thrombopoietin mimetic peptide; D013926:Thrombopoietin