title: Feedback control of ErbB2 via ERK-mediated phosphorylation of a conserved threonine in the juxtamembrane domain.
abstract: Tyrosine kinase activity of the asymmetric EGFR homodimer is negatively regulated via ERK-mediated phosphorylation of Thr-669 in the juxtamembrane domain. In the present study, we investigated in human breast cancer cells whether a similar mechanism plays a role in the feedback regulation of the ErbB2/ErbB3 heterodimer, the most potent ErbB receptor dimer. Constitutive tyrosine phosphorylation of ErbB2 and ErbB3 was significantly decreased in phorbol ester- and growth factor-treated BT-474 and MDA-MB-453 cells. In contrast to the decreased tyrosine phosphorylation, Phos-tag Western blot analysis revealed that TPA induced phosphorylation of ErbB2 in an ERK-dependent manner. The target threonine residue corresponding to EGFR Thr-669 and the surrounding residues are highly conserved in ErbB2, but not in ErbB3. Therefore, we demonstrated ERK-mediated phosphorylation of ErbB2 at Thr-677 by generating phospho-specific monoclonal antibodies. Moreover, treatment with trametinib and SCH772984, inhibitors of the MEK-ERK pathway, and substitution of Thr-677 to alanine impaired the feedback inhibition of ErbB2 and ErbB3. These results demonstrated that ERK-mediated phosphorylation of the conserved threonine is a common mechanism for the negative feedback control of active ErbB receptor dimers.
authors.affiliation: Department of Cancer Cell Biology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kawasaki
authors.affiliation: Department of Cancer Cell Biology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Sakimura
authors.affiliation: Department of Cancer Cell Biology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
authors.forename: Chul Min
authors.initials: CM
authors.lastname: Park
authors.affiliation: Department of Cancer Cell Biology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
authors.forename: Rika
authors.initials: R
authors.lastname: Tomaru
authors.affiliation: Department of Cancer Cell Biology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Department of Immunology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Ozawa
authors.affiliation: Department of Cancer Cell Biology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Cancer Cell Biology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Narita
authors.affiliation: Department of Immunology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kishi
authors.affiliation: Department of Immunology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Muraguchi
authors.affiliation: Department of Cancer Cell Biology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sakurai
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000235:genetics; D000072417:Protein Domains; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D020893:Receptor, ErbB-3 / Q000235:genetics / Q000378:metabolism; D013912:Threonine / Q000235:genetics / Q000378:metabolism*
chemical_list: D048049:Extracellular Signal-Regulated MAP Kinases; D009097:Multienzyme Complexes; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; D013912:Threonine; C508053:ERBB2 protein, human; C581292:ERBB3 protein, human