scholarly journals Epidermal growth factor induces phosphorylation of extracellular signal-regulated kinase 2 via multiple pathways.

1993 ◽  
Vol 13 (12) ◽  
pp. 7248-7256 ◽  
Author(s):  
B M Burgering ◽  
A M de Vries-Smits ◽  
R H Medema ◽  
P C van Weeren ◽  
L G Tertoolen ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Calcium Influx ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Alternative Pathways ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
A Cell ◽  
Epidermal Growth

Expression of p21rasAsn-17, a dominant negative mutant of p21ras that blocks p21ras activation by growth factors, inhibits activation of extracellular signal-regulated kinase 2 (ERK2) by insulin and platelet-derived growth factor in rat-1 cells [A. M. M. de Vries-Smits, B. M. T. Burgering, S. J. Leevers, C. J. Marshall, and J. L. Bos, Nature (London) 357:602-604, 1992]. Here we report that expression of p21rasAsn-17 does not abolish epidermal growth factor (EGF)-induced phosphorylation of ERK2 in fibroblasts. Since EGF activates p21ras in these cells, this indicates that EGF induces a p21ras-independent pathway for the phosphorylation of ERK2 as well. We investigated whether activation of protein kinase C (PKC) or increase in intracellular calcium could be involved in p21ras-independent signaling. In rat-1 cells, inhibition of either PKC, by prolonged 12-O-tetradecanoylphorbol-13-acetate (TPA) pretreatment, or calcium influx, by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) pretreatment, did not abolish EGF-induced ERK2 phosphorylation. However, a combined inhibition of both p21ras and calcium influx, but not PKC, resulted in a complete inhibition of EGF-induced ERK2 phosphorylation. In contrast, in Swiss 3T3 cells, inhibition of both p21ras activation and TPA-sensitive PKC, but not calcium influx, inhibited EGF-induced ERK2 phosphorylation. These results demonstrate that in fibroblasts, EGF induces alternative pathways of ERK2 phosphorylation in a cell-type-specific manner.

scholarly journals Epidermal growth factor induces phosphorylation of extracellular signal-regulated kinase 2 via multiple pathways

1993 ◽  
Vol 13 (12) ◽  
pp. 7248-7256
Author(s):  
B M Burgering ◽  
A M de Vries-Smits ◽  
R H Medema ◽  
P C van Weeren ◽  
L G Tertoolen ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Calcium Influx ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Alternative Pathways ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
A Cell ◽  
Epidermal Growth

Expression of p21rasAsn-17, a dominant negative mutant of p21ras that blocks p21ras activation by growth factors, inhibits activation of extracellular signal-regulated kinase 2 (ERK2) by insulin and platelet-derived growth factor in rat-1 cells [A. M. M. de Vries-Smits, B. M. T. Burgering, S. J. Leevers, C. J. Marshall, and J. L. Bos, Nature (London) 357:602-604, 1992]. Here we report that expression of p21rasAsn-17 does not abolish epidermal growth factor (EGF)-induced phosphorylation of ERK2 in fibroblasts. Since EGF activates p21ras in these cells, this indicates that EGF induces a p21ras-independent pathway for the phosphorylation of ERK2 as well. We investigated whether activation of protein kinase C (PKC) or increase in intracellular calcium could be involved in p21ras-independent signaling. In rat-1 cells, inhibition of either PKC, by prolonged 12-O-tetradecanoylphorbol-13-acetate (TPA) pretreatment, or calcium influx, by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) pretreatment, did not abolish EGF-induced ERK2 phosphorylation. However, a combined inhibition of both p21ras and calcium influx, but not PKC, resulted in a complete inhibition of EGF-induced ERK2 phosphorylation. In contrast, in Swiss 3T3 cells, inhibition of both p21ras activation and TPA-sensitive PKC, but not calcium influx, inhibited EGF-induced ERK2 phosphorylation. These results demonstrate that in fibroblasts, EGF induces alternative pathways of ERK2 phosphorylation in a cell-type-specific manner.

scholarly journals Phosphorylation of Rac1 T108 by Extracellular Signal-Regulated Kinase in Response to Epidermal Growth Factor: a Novel Mechanism To Regulate Rac1 Function

2013 ◽  
Vol 33 (22) ◽  
pp. 4538-4551 ◽  
Author(s):  
Junfeng Tong ◽  
Laiji Li ◽  
Barbara Ballermann ◽  
Zhixiang Wang
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Rho Gtpases ◽  
Fluorescent Protein ◽  
Phosphorylation Site ◽  
Kinase Assay ◽  
Nucleotide Exchange ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Epidermal Growth

Accumulating evidence has implicated Rho GTPases, including Rac1, in many aspects of cancer development. Recent findings suggest that phosphorylation might further contribute to the tight regulation of Rho GTPases. Interestingly, sequence analysis of Rac1 shows that Rac1 T108 within the106PNTP109motif is likely an extracellular signal-regulated kinase (ERK) phosphorylation site and that Rac1 also has an ERK docking site,183KKRKRKCLLL192(D site), at the C terminus. Indeed, we show here that both transfected and endogenous Rac1 interacts with ERK and that this interaction is mediated by its D site. Green fluorescent protein (GFP)-Rac1 is threonine (T) phosphorylated in response to epidermal growth factor (EGF), and EGF-induced Rac1 threonine phosphorylation is dependent on the activation of ERK. Moreover, mutant Rac1 with the mutation of T108 to alanine (A) is not threonine phosphorylated in response to EGF.In vitroERK kinase assay further shows that pure active ERK phosphorylates purified Rac1 but not mutant Rac1 T108A. We also show that Rac1 T108 phosphorylation decreases Rac1 activity, partially due to inhibiting its interaction with phospholipase C-γ1 (PLC-γ1). T108 phosphorylation targets Rac1 to the nucleus, which isolates Rac1 from other guanine nucleotide exchange factors (GEFs) and hinders Rac1's role in cell migration. We conclude that Rac1 T108 is phosphorylated by ERK in response to EGF, which plays an important role in regulating Rac1.

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