title: Structural basis for specificity of TGFβ family receptor small molecule inhibitors.
abstract: Transforming growth factor-β (TGFβ) receptor kinase inhibitors have a great therapeutic potential. SB431542 is one of the mainly used kinase inhibitors of the TGFβ/Activin pathway receptors, but needs improvement of its EC(50) (EC(50)=1 μM) to be translated to clinical use. A key feature of SB431542 is that it specifically targets receptors from the TGFβ/Activin pathway but not the closely related receptors from the bone morphogenic proteins (BMP) pathway. To understand the mechanisms of this selectivity, we solved the crystal structure of the TGFβ type I receptor (TβRI) kinase domain in complex with SB431542. We mutated TβRI residues coordinating SB431542 to their counterparts in activin-receptor like kinase 2 (ALK2), a BMP receptor kinase, and tested the kinase activity of mutated TβRI. We discovered that a Ser280Thr mutation yielded a TβRI variant that was resistant to SB431542 inhibition. Furthermore, the corresponding Thr283Ser mutation in ALK2 yielded a BMP receptor sensitive to SB431542. This demonstrated that Ser280 is the key determinant of selectivity for SB431542. This work provides a framework for optimising the SB431542 scaffold to more potent and selective inhibitors of the TGFβ/Activin pathway.
authors: Center for Systems Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5.
authors: Abiodun A
authors: AA
authors: Ogunjimi
authors: Center for Systems Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5.
authors: Elton
authors: E
authors: Zeqiraj
authors: Center for Systems Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5.
authors: Derek F
authors: DF
authors: Ceccarelli
authors: Center for Systems Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5; Dept. of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8. Electronic address: sicheri@lunenfeld.ca.
authors: Frank
authors: F
authors: Sicheri
authors: Center for Systems Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5; Dept. of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8. Electronic address: wrana@lunenfeld.ca.
authors: Jeffrey L
authors: JL
authors: Wrana
authors: Center for Systems Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5. Electronic address: ldavid@lunenfeld.ca.
authors: Laurent
authors: L
authors: David
mesh_terms: D030201:Activin Receptors, Type I / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D028341:Activins / Q000378:metabolism; D001549:Benzamides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D019485:Bone Morphogenetic Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D004149:Dioxoles / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D015195:Drug Design; D057809:HEK293 Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D008958:Models, Molecular; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013379:Substrate Specificity; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D001549:Benzamides; D019485:Bone Morphogenetic Proteins; D004149:Dioxoles; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D028341:Activins; D012694:Serine; D017346:Protein Serine-Threonine Kinases; C425423:ACVR1 protein, human; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I