Grb2 negatively regulates epidermal growth factor-induced phospholipase C-gamma1 activity through the direct interaction with tyrosine-phosphorylated phospholipase C-gamma1.
Phospholipase C-gamma1 (PLC-gamma1) plays pivotal roles in cellular growth and proliferation. Upon the stimulation of growth factors and hormones, PLC-gamma1 is rapidly phosphorylated at three known sites; Tyr771, Tyr783 and Tyr1254 and its enzymatic activity is up-regulated. In this study, we demonstrate for the first time that Grb2, an adaptor protein, specifically interacts with tyrosine-phosphorylated PLC-gamma1 at Tyr783. The association of Grb2 with PLC-gamma1 was induced by the treatment with epidermal growth factor (EGF). Replacement of Tyr783 with Phe completely blocked EGF-induced interaction of PLC-gamma1 with Grb2, indicating that tyrosine phosphorylation of PLC-gamma1 at Tyr783 is essential for the interaction with Grb2. Interestingly, the depletion of Grb2 from HEK-293 cells by RNA interference significantly enhanced increased EGF-induced PLC-gamma1 enzymatic activity and mobilization of the intracellular Ca2+, while it did not affect EGF-induced tyrosine phosphorylation of PLC-gamma1. Furthermore, overexpression of Grb2 inhibited PLC-gamma1 enzymatic activity. Taken together, these results suggest Grb2, in addition to its key function in signaling through Ras, may have a negatively regulatory role on EGF-induced PLC-gamma1 activation.
Choi
Jang Hyun
JH
Department of Life Science, Pohang University of Science and Technology, San 31, Hyojadong, Pohang, Kyungbuk, 790-784, South Korea.
Hong
Won-Pyo
WP
Yun
Sanguk
S
Kim
Hyeon Soo
HS
Lee
Jong-Ryul
JR
Park
Jong Bae
JB
Bae
Yun Soo
YS
Ryu
Sung Ho
SH
Suh
Pann-Ghill
PG
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D051380:GRB2 Adaptor Protein; D015870:Gene Expression; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D051966:Phospholipase C gamma; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D010446:Peptide Fragments; D019269:Phosphatidylinositol 4,5-Diphosphate; D034741:RNA, Small Interfering; D019000:Phosphotyrosine; D014443:Tyrosine; D004815:Epidermal Growth Factor; D015544:Inositol 1,4,5-Trisphosphate; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D018631:ras Proteins; D002118:Calcium