Formation of distinct signalling complexes involving phosphatidylinositol 3-kinase activity with stimulation of epidermal growth factor or insulin-like growth factor-I in human skin fibroblasts.
We recently described a better correlation of DNA synthesis with phosphatidylinositol (PI) 3-kinase than with mitogen-activated protein (MAP) kinase stimulated by insulin-like growth factor (IGF)-1 or epidermal growth factor (EGF) in human skin fibroblasts (Takahashi et al., 1997, Endocrinology 138:741-750). IGF-I-induced PI 3-kinase activation is generally mediated via insulin receptor substrate (IRS)-1, but EGF-induced PI 3-kinase activation is mediated by various signalling molecules such as ErbB3 and c-Cbl in different cells. We therefore investigated the mechanism regulating PI 3-kinase in human skin fibroblasts by comparing complexes involving PI 3-kinase when stimulated by IGF-I or EGF and found that p115 and p105, which were tyrosine-phosphorylated by EGF stimulation and associated with SHP-2, were also associated with the p85 subunit of PI 3-kinase by EGF. Anti-SHP-2 and anti-p85 subunits of PI 3-kinase antibodies did not coprecipitate tyrosine-phosphorylated EGF receptor or ErbB3; in addition, p115 and p105 appeared to be distinct from tyrosine-phosphorylated c-Cbl. Thus, tyrosine-phosphorylated p115 and p105 may provide a novel platform recruiting p85, which may simultaneously bind to SHP-2. In contrast, tyrosine phosphorylation of p115 or p 105 was undetectable by immunoblot with IGF-I stimulation, and PI 3-kinase activity was mediated via IRS-1 phosphorylated with IGF-I stimulation, little of which was associated with SHP-2. Thus, EGF and IGF-I cause formation of a distinct signalling complex which associates with p85 subunit of PI 3-kinase.
Takahashi
Y
Y
Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Akanuma
Y
Y
Yazaki
Y
Y
Kadowaki
T
T
D048868:Adaptor Proteins, Signal Transducing; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005347:Fibroblasts / Q000737:chemistry / Q000201:enzymology; D051380:GRB2 Adaptor Protein; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins; D019869:Phosphatidylinositol 3-Kinases / Q000032:analysis / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D015398:Signal Transduction / Q000187:drug effects*; D012867:Skin / Q000166:cytology / Q000201:enzymology*; D014443:Tyrosine / Q000378:metabolism; D018909:src Homology Domains / Q000502:physiology
D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D014443:Tyrosine; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I; D019869:Phosphatidylinositol 3-Kinases; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases