Inhibition of transforming growth factor-beta signaling by low molecular weight compounds interfering with ATP- or substrate-binding sites of the TGF beta type I receptor kinase.
Transforming growth factor-beta (TGFbeta) is a potent regulator of cell proliferation, differentiation, apoptosis, and migration. TGF-beta type I receptor (TbetaR-I), which has intrinsic serine/threonine kinase activity, is a key component in activation of intracellular TGFbeta signaling. We studied two different classes of TbetaR-I inhibitors, i.e., compounds interfering with the ATP-binding site of the kinase and substrate-mimicking peptides. We found that pyridinylimidazole compounds inhibited TbetaR-I kinase at micromolar concentration. A representative compound, SB203580, inhibited in vivo Smad2 phosphorylation by TbetaR-I and affected TGFbeta-dependent transcriptional activation. Peptides mimicking the TbetaR-I phosphorylation sites at the C-terminus of Smad2 also inhibited the autophosphorylation of TbetaR-I and phosphorylation of Smad2 by TbetaR-I in vitro and in vivo, whereas a similar peptide from Smad5 was without effect. The substrate-mimicking peptide, fused to penetratin, inhibited a TGFbeta1-dependent transcriptional response in a luciferase reporter assay and ligand-dependent growth inhibition of Mv1Lu cells. Thus, the substrate-mimetic peptide is a new type of specific inhibitor of the TGFbeta signaling in vivo.
Ludwig Institute for Cancer Research, Box 595, SE-751 24 Uppsala, Sweden.
Ihor
I
Yakymovych
Ulla
U
Engström
Susanne
S
Grimsby
Carl-Henrik
CH
Heldin
Serhiy
S
Souchelnytskyi
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D051943:Antennapedia Homeodomain Protein; D001665:Binding Sites / Q000187:drug effects; D019556:COS Cells; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018398:Homeodomain Proteins / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D008907:Mink; D018716:Molecular Mimicry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009687:Nuclear Proteins; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000138:chemical synthesis / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D051899:Smad2 Protein; D051900:Smad3 Protein; D013379:Substrate Specificity; D015534:Trans-Activators / Q000378:metabolism / Q000494:pharmacology; D014157:Transcription Factors; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology*
D051943:Antennapedia Homeodomain Protein; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D018398:Homeodomain Proteins; D007093:Imidazoles; D009687:Nuclear Proteins; D010446:Peptide Fragments; D011725:Pyridines; D018125:Receptors, Transforming Growth Factor beta; D011993:Recombinant Fusion Proteins; D051899:Smad2 Protein; D051900:Smad3 Protein; D015534:Trans-Activators; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000255:Adenosine Triphosphate; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; C093642:SB 203580