title: The kinase activity of the Ser/Thr kinase BUB1 promotes TGF-β signaling.
abstract: Transforming growth factor-β (TGF-β) signaling regulates cell proliferation and differentiation, which contributes to development and disease. Upon binding TGF-β, the type I receptor (TGFBRI) binds TGFBRII, leading to the activation of the transcription factors SMAD2 and SMAD3. Using an RNA interference screen of the human kinome and a live-cell reporter for TGFBR activity, we identified the kinase BUB1 (budding uninhibited by benzimidazoles-1) as a key mediator of TGF-β signaling. BUB1 interacted with TGFBRI in the presence of TGF-β and promoted the heterodimerization of TGFBRI and TGFBRII. Additionally, BUB1 interacted with TGFBRII, suggesting the formation of a ternary complex. Knocking down BUB1 prevented the recruitment of SMAD3 to the receptor complex, the phosphorylation of SMAD2 and SMAD3 and their interaction with SMAD4, SMAD-dependent transcription, and TGF-β-mediated changes in cellular phenotype including epithelial-mesenchymal transition (EMT), migration, and invasion. Knockdown of BUB1 also impaired noncanonical TGF-β signaling mediated by the kinases AKT and p38 MAPK (mitogen-activated protein kinase). The ability of BUB1 to promote TGF-β signaling depended on the kinase activity of BUB1. A small-molecule inhibitor of the kinase activity of BUB1 (2OH-BNPP1) and a kinase-deficient mutant of BUB1 suppressed TGF-β signaling and formation of the ternary complex in various normal and cancer cell lines. 2OH-BNPP1 administration to mice bearing lung carcinoma xenografts reduced the amount of phosphorylated SMAD2 in tumor tissue. These findings indicated that BUB1 functions as a kinase in the TGF-β pathway in a role beyond its established function in cell cycle regulation and chromosome cohesion.
authors.affiliation: Center for Molecular Imaging, University of Michigan, Ann Arbor, MI 48109, USA. Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Shyam
authors.initials: S
authors.lastname: Nyati
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Katrina
authors.initials: K
authors.lastname: Schinske-Sebolt
authors.affiliation: Single Molecule Analysis in Real-Time (SMART) Center, University of Michigan, Ann Arbor, MI 48109, USA. Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Sethuramasundaram
authors.initials: S
authors.lastname: Pitchiaya
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Katerina
authors.initials: K
authors.lastname: Chekhovskiy
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Areeb
authors.initials: A
authors.lastname: Chator
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Nauman
authors.initials: N
authors.lastname: Chaudhry
authors.affiliation: Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Dosch
authors.affiliation: Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Marcian E
authors.initials: ME
authors.lastname: Van Dort
authors.affiliation: Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Sooryanarayana
authors.initials: S
authors.lastname: Varambally
authors.affiliation: Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA. Michigan Center for Translational Pathology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Chandan
authors.initials: C
authors.lastname: Kumar-Sinha
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Mukesh Kumar
authors.initials: MK
authors.lastname: Nyati
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Dipankar
authors.initials: D
authors.lastname: Ray
authors.affiliation: Single Molecule Analysis in Real-Time (SMART) Center, University of Michigan, Ann Arbor, MI 48109, USA. Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Nils G
authors.initials: NG
authors.lastname: Walter
authors.affiliation: Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
authors.forename: Hongtao
authors.initials: H
authors.lastname: Yu
authors.affiliation: Center for Molecular Imaging, University of Michigan, Ann Arbor, MI 48109, USA. Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Brian Dale
authors.initials: BD
authors.lastname: Ross
authors.affiliation: Center for Molecular Imaging, University of Michigan, Ann Arbor, MI 48109, USA. Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA. alnawaz@med.umich.edu.
authors.forename: Alnawaz
authors.initials: A
authors.lastname: Rehemtulla
mesh_terms: D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D019281:Dimerization; D005455:Fluorescent Antibody Technique; D055785:Gene Knockdown Techniques; D057166:High-Throughput Screening Assays; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D051379:Mice; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D018125:Receptors, Transforming Growth Factor beta / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D051896:Smad Proteins, Receptor-Regulated / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000502:physiology*
chemical_list: D034741:RNA, Small Interfering; D018125:Receptors, Transforming Growth Factor beta; D051896:Smad Proteins, Receptor-Regulated; D016212:Transforming Growth Factor beta; C584277:BUB1 protein, human; D017346:Protein Serine-Threonine Kinases