TY - JOUR
T1 - Tyrosine phosphorylation of the EGF receptor by the kinase Jak2 is induced by growth hormone
AU - Yamauchi, Toshimasa
AU - Ueki, Kohjiro
AU - Tobe, Kazuyuki
AU - Tamemoto, Hiroyuki
AU - Sekine, Nobuo
AU - Wada, Mitsufumi
AU - Honjo, Masaru
AU - Takahashi, Michio
AU - Takahashi, Tokiharu
AU - Hirai, Hisamaru
AU - Tushima, Toshio
AU - Akanuma, Yasuo
AU - Fujita, Toshiro
AU - Komuro, Issei
AU - Yazaki, Yoshio
AU - Kadowaki, Takashi
PY - 1997/11/6
Y1 - 1997/11/6
N2 - When growth hormone binds to its receptor, which belongs to the cytokine receptor superfamily, it activates the Janus kinase Jak2 which has tyrosine- kinase activity and initiates an activation of several key intracellular proteins (for example, mitogen-activated protein (MAP) kinases) that eventually execute the biological actions induced by growth hormone, including the expression of particular genes. In contrast to receptors that themselves have tyrosine kinase activity, the signalling pathways leading to MAP kinase activation that are triggered by growth hormone are poorly understood, but appear to be mediated by the proteins Grb2 and Shc. We now show that growth hormone stimulates tyrosine phosphorylation of the receptor for epidermal growth factor (EGFR) and its association with Grb2 and at the same time stimulates MAP kinase activity in liver, an important target tissue of growth hormone. Expression of EGFR and its mutants revealed that growth- hormone-induced activation of MAP kinase and expression of the transcription factor c-fos requires phosphorylation of tyrosines on EGFR, but not its own intrinsic tyrosine-kinase activity. Moreover, tyrosine at residue 1,068 of the EGFR is proposed to be one of the principal phosphorylation sites and Grb2-binding sites stimulated by growth hormone via Jak2. Our results indicate that the role of EGFR in signalling by growth hormone is to be phosphorylated by Jak2, thereby providing docking sites for Grb2 and activating MAP kinases and gene expression, independently of the intrinsic tyrosine kinase activity of EGFR. This may represent a novel cross-talk pathway between the cytokine receptor superfamily and growth factor receptor.
AB - When growth hormone binds to its receptor, which belongs to the cytokine receptor superfamily, it activates the Janus kinase Jak2 which has tyrosine- kinase activity and initiates an activation of several key intracellular proteins (for example, mitogen-activated protein (MAP) kinases) that eventually execute the biological actions induced by growth hormone, including the expression of particular genes. In contrast to receptors that themselves have tyrosine kinase activity, the signalling pathways leading to MAP kinase activation that are triggered by growth hormone are poorly understood, but appear to be mediated by the proteins Grb2 and Shc. We now show that growth hormone stimulates tyrosine phosphorylation of the receptor for epidermal growth factor (EGFR) and its association with Grb2 and at the same time stimulates MAP kinase activity in liver, an important target tissue of growth hormone. Expression of EGFR and its mutants revealed that growth- hormone-induced activation of MAP kinase and expression of the transcription factor c-fos requires phosphorylation of tyrosines on EGFR, but not its own intrinsic tyrosine-kinase activity. Moreover, tyrosine at residue 1,068 of the EGFR is proposed to be one of the principal phosphorylation sites and Grb2-binding sites stimulated by growth hormone via Jak2. Our results indicate that the role of EGFR in signalling by growth hormone is to be phosphorylated by Jak2, thereby providing docking sites for Grb2 and activating MAP kinases and gene expression, independently of the intrinsic tyrosine kinase activity of EGFR. This may represent a novel cross-talk pathway between the cytokine receptor superfamily and growth factor receptor.
U2 - 10.1038/36369
DO - 10.1038/36369
M3 - Article
C2 - 9363897
SN - 0028-0836
VL - 390
SP - 91
EP - 96
JO - Nature
JF - Nature
IS - 6655
ER -