Biochemical and biological responses induced by coupling of Gab1 to phosphatidylinositol 3-kinase in RET-expressing cells

Kengo Maeda, Hideki Murakami, Reiko Yoshida, Masatoshi Ichihara, Akihiro Abe, Makoto Hirai, Toyoaki Murohara, Masahide Takahashi

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23 Citations (Scopus)


Grb2-associated binder-1 (Gab1) is a docking protein closely related to insulin receptor substrates. We previously reported that tyrosine 1062 in RET receptor tyrosine kinase activated by glial cell line-derived neurotrophic factor (GDNF) represents a binding site for the Shc-Grb2-Gab1 complex, and that the p85 subunit of phosphatidylinositol 3-kinase (PI3K) and SHP2 tyrosine phosphatase is associated with Gab1 in GDNF-treated cells. In the present study, we further analyzed the physiological roles of Gab1 downstream of RET, using Gab1 mutants that lack the binding sites for PI3K (Gab1 PI3K-m) or SHP-2 (Gab1 SHP2-m). Expression of Gab1 PI3K-m in SK-N-MC human primitive neuroectodermal tumor cells expressing wild-type RET markedly impaired Akt phosphorylation, Rac1 activation, and lamellipodia formation that were induced by GDNF whereas expression of Gab1 SHP2-m partially impaired Erk activation. Furthermore, expression of Gab1 PI3K-m, but not Gab1 SHP2-m, in TT human medullary thyroid carcinoma cells expressing RET with a multiple endocrine neoplasia 2A mutation enhanced cytochrome c release, and apoptosis induced by etoposide, suggesting that PI3K is involved in survival of TT cells via a mitochondrial pathway. These findings demonstrated that coupling of Gab1 to PI3K is important for biological responses in RET-expressing cells.

Original languageEnglish
Pages (from-to)345-354
Number of pages10
JournalBiochemical and Biophysical Research Communications
Issue number1
Publication statusPublished - 08-10-2004
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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