scholarly journals Inactivation of Glycogen Synthase Kinase-3 by Epidermal Growth Factor Is Mediated by Mitogen-activated Protein Kinase/p90 Ribosomal Protein S6 Kinase Signaling Pathway in NIH/3T3 Cells

1995 ◽  
Vol 270 (3) ◽  
pp. 987-990 ◽  
Author(s):  
Hagit Eldar-Finkelman ◽  
Rony Seger ◽  
Jackie R. Vandenheede ◽  
Edwin G. Krebs
Keyword(s):  
Glycogen Synthase ◽  
Mitogen Activated Protein Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
3T3 Cells ◽  
S6 Kinase ◽  
Ribosomal Protein S6 ◽  
Mitogen Activated Protein ◽  
Epidermal Growth ◽  
Nih 3T3 ◽  
Kinase Signaling Pathway

scholarly journals Tyrosine phosphorylation sites at amino acids 239 and 240 of Shc are involved in epidermal growth factor-induced mitogenic signaling that is distinct from Ras/mitogen-activated protein kinase activation.

1997 ◽  
Vol 17 (4) ◽  
pp. 1824-1831 ◽  
Author(s):  
N Gotoh ◽  
M Toyoda ◽  
M Shibuya
Keyword(s):  
Growth Factor ◽  
Protein Kinase ◽  
Cell Growth ◽  
Epidermal Growth Factor ◽  
Mitogen Activated Protein Kinase ◽  
Phosphorylation Sites ◽  
3T3 Cells ◽  
Mitogen Activated Protein ◽  
Epidermal Growth ◽  
Nih 3T3

Epidermal growth factor (EGF) induces tyrosine phosphorylation of the Shc adapter protein, which plays an important role in EGF-stimulated mitogenesis. Shc stimulates Ras/mitogen-activated protein kinase (MAPK) through forming a complex with Grb2 at the phosphorylated tyrosine (Y) residue 317. In this study, we identified novel phosphorylation sites of Shc, at Y239 and Y240. To define the Shc pathway further, we used NIH 3T3 cells expressing the previously characterized mutant EGF receptor (EGF-R) which lacks all known autophosphorylation sites but retains EGF-stimulated mitogenesis with selective phosphorylation of Shc. We constructed wild-type (WT) or mutant Shc cDNAs in which Y317 or/and Y239 and Y240 are replaced with phenylalanine (F) and introduced them into NIH 3T3 cells expressing WT or mutant EGF-R. In the WT EGF-R-expressing cells, the Y239/240/317F Shc, but not Y317F or Y239/240F Shc, decreased EGF-stimulated cell growth. In the mutant EGF-R-expressing cells, Y317F Shc or Y239/240F Shc decreased EGF-stimulated cell growth significantly, though Y317F was a little more potent than Y239/240F. Although cells expressing the Y317F Shc hardly activated MAPK in response to EGF, cells expressing the Y239/240F Shc fully activated MAPK. In contrast, Y239/240F Shc, but not Y317F Shc, reduced the EGF-induced c-myc message. These results suggest that Shc activates two distinct signaling pathways, Y317 to Ras/MAPK and Y239 and Y240 to another pathway including Myc, and that both are involved in EGF-induced mitogenic signaling.

scholarly journals Wortmannin inhibits the effects of insulin and serum on the activities of glycogen synthase kinase-3 and mitogen-activated protein kinase

1994 ◽  
Vol 303 (1) ◽  
pp. 15-20 ◽  
Author(s):  
G I Welsh ◽  
E J Foulstone ◽  
S W Young ◽  
J M Tavaré ◽  
C G Proud
Keyword(s):  
Map Kinase ◽  
Phorbol Ester ◽  
Glycogen Synthase ◽  
Chinese Hamster Ovary Cells ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
Parental Cell Line ◽  
S6 Kinase ◽  
Mitogen Activated Protein ◽  
Kinase Pathway

We have previously shown that insulin causes inactivation of glycogen synthase kinase-3 (GSK-3) in Chinese hamster ovary cells over-expressing the human insulin receptor (CHO.T cells). We now show that serum and phorbol ester also cause rapid inactivation of GSK-3, both in CHO.T cells and in the nontransfected parental cell line, CHO.K1 cells. Rapamycin was without effect on the inactivation of GSK-3 by insulin, serum or phorbol ester, indicating that the p70 S6 kinase pathway is not involved. In contrast, wortmannin, a potent inhibitor of phosphatidylinositol 3-kinase, blocked the effects of both insulin and serum on GSK-3 activity, and also substantially reduced the activation of both p90 S6 kinase (by insulin) and mitogen-activated protein (MAP) kinase (by insulin and serum). These findings imply (i) that GSK-3 activity is regulated by a cascade involving MAP kinase and p90 S6 kinase and (ii) that wortmannin affects an early step in the MAP kinase pathway. One can infer from this that GSK-3 may be an important regulatory enzyme for the control of several biosynthetic pathways, key enzymes in which are regulated by GSK-3-mediated phosphorylation. Wortmannin had a smaller effect on the activation of MAP kinase by phorbol ester, indicating that phorbol esters may stimulate MAP kinase by a different or additional mechanism to that employed by insulin or serum. Wortmannin had very little effect on the inactivation of GSK-3 by phorbol ester: possible reasons for this are discussed.

Activation of mitogen-activated protein kinase kinase by v-Raf in NIH 3T3 cells and in vitro

Science ◽  
1992 ◽  
Vol 257 (5075) ◽  
pp. 1404-1407 ◽  
Author(s):  
P Dent ◽  
W Haser ◽  
T. Haystead ◽  
L. Vincent ◽  
T. Roberts ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
3T3 Cells ◽  
Mitogen Activated Protein ◽  
Nih 3T3 ◽  
Protein Kinase Kinase ◽  
Nih 3T3 Cells

scholarly journals Kinase-deficient Pak1 mutants inhibit Ras transformation of Rat-1 fibroblasts.

1997 ◽  
Vol 17 (8) ◽  
pp. 4454-4464 ◽  
Author(s):  
Y Tang ◽  
Z Chen ◽  
D Ambrose ◽  
J Liu ◽  
J B Gibbs ◽  
...  
Keyword(s):  
Cellular Transformation ◽  
Mitogen Activated Protein Kinase ◽  
3T3 Cells ◽  
Serine Threonine Kinase ◽  
Threonine Kinase ◽  
Jun Kinase ◽  
Ras Activation ◽  
Mitogen Activated Protein ◽  
Nih 3T3 ◽  
Dependent Mechanism

Among the mechanisms by which the Ras oncogene induces cellular transformation, Ras activates the mitogen-activated protein kinase (MAPK or ERK) cascade and a related cascade leading to activation of Jun kinase (JNK or SAPK). JNK is additionally regulated by the Ras-related G proteins Rac and Cdc42. Ras also regulates the actin cytoskeleton through an incompletely elucidated Rac-dependent mechanism. A candidate for the physiological effector for both JNK and actin regulation by Rac and Cdc42 is the serine/threonine kinase Pak (p65pak). We show here that expression of a catalytically inactive mutant Pak, Pak1(R299), inhibits Ras transformation of Rat-1 fibroblasts but not of NIH 3T3 cells. Typically, 90 to 95% fewer transformed colonies were observed in cotransfection assays with Rat-1 cells. Pak1(R299) did not inhibit transformation by the Raf oncogene, indicating that inhibition was specific for Ras. Furthermore, Rat-1 cell lines expressing Pak1(R299) were highly resistant to Ras transformation, while cells expressing wild-type Pak1 were efficiently transformed by Ras. Pak1(L83,L86,R299), a mutant that fails to bind either Rac or Cdc42, also inhibited Ras transformation. Rac and Ras activation of JNK was inhibited by Pak1(R299) but not by Pak1(L83,L86,R299). Ras activation of ERK was inhibited by both Pak1(R299) and Pak1(L83,L86,R299), while neither mutant inhibited Raf activation of ERK. These results suggest that Pak1 interacts with components essential for Ras transformation and that inhibition can be uncoupled from JNK but not ERK signaling.

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