Activity and cellular localization of an oncogenic glioblastoma multiforme-associated EGF receptor mutant possessing a duplicated kinase domain

Byram Ozer, G. J. Wiepz, P. J. Bertics

Research output: Contribution to journalArticle

Abstract

A mutation of the epidermal growth factor receptor (EGFR) that results in a tandem kinase domain duplication (TKD-EGFR) has been described in glioblastoma multiforme biopsies and cell lines. Although the TKD-EGFR confers tumorigenicity, little is known about the molecular underpinnings of receptor dysregulation. Therefore, we transfected B82L mouse fibroblast cells devoid of endogenous EGFR to determine the molecular mechanisms of receptor activation when expressed in cells as well as the contribution of each duplicated kinase domain to receptor phosphorylation. The TKD-EGFR displayed chronically elevated basal autophosphorylation at five known phosphotyrosine sites. The chronically phosphorylated TKD-EGFR was also resistant to competitive inhibition of ligand-binding compared with wild-type EGFR (WT-EGFR) and showed undetectable levels of basal dimerization, suggesting the TKD-EGFR escapes known mechanisms of receptor downregulation. Immunofluorescence analyses revealed a substantial portion of the TKD-EGFR resides in the cytosol in an activated state, although surface-localized subsets of the receptor retain ligand responsiveness. Kinase activity-deficient knockouts of the N-terminal or the C-terminal kinase domains generated TKD-EGFRs that recapitulate the autophosphorylation/localization patterns of a constitutively activated receptor versus a WT-like EGFR, respectively. Investigation of the molecular activity of the TKD-EGFR yields evidence for a unique mechanism of constitutive activity and dual kinase domain activation.

Original languageEnglish (US)
Pages (from-to)855-864
Number of pages10
JournalOncogene
Volume29
Issue number6
DOIs
StatePublished - Feb 1 2010
Externally publishedYes

Fingerprint

Glioblastoma
Epidermal Growth Factor Receptor
Phosphotransferases
Ligands
Phosphotyrosine
Dimerization
Cytosol
Fluorescent Antibody Technique
Down-Regulation
Fibroblasts
Phosphorylation
Biopsy
Cell Line
Mutation

Keywords

  • Constitutive activity
  • Duplicate kinase domains
  • EGF receptor (EGFR)
  • Glioblastoma multiforme

ASJC Scopus subject areas

  • Cancer Research
  • Genetics
  • Molecular Biology

Cite this

Activity and cellular localization of an oncogenic glioblastoma multiforme-associated EGF receptor mutant possessing a duplicated kinase domain. / Ozer, Byram; Wiepz, G. J.; Bertics, P. J.

In: Oncogene, Vol. 29, No. 6, 01.02.2010, p. 855-864.

Research output: Contribution to journalArticle

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