scholarly journals The Tyrosine Phosphatase SHP-2 Is Required for Sustained Activation of Extracellular Signal-Regulated Kinase and Epithelial Morphogenesis Downstream from the Met Receptor Tyrosine Kinase

2000 ◽  
Vol 20 (22) ◽  
pp. 8513-8525 ◽  
Author(s):  
Christiane R. Maroun ◽  
Monica A. Naujokas ◽  
Marina Holgado-Madruga ◽  
Albert J. Wong ◽  
Morag Park
Keyword(s):  
Growth Factor ◽  
Tyrosine Phosphatase ◽  
Epithelial Morphogenesis ◽  
Met Receptor ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Transient Activation ◽  
Extracellular Signal ◽  
Positive Modulator ◽  
Sustained Activation

ABSTRACT Epithelial morphogenesis is critical during development and wound healing, and alterations in this program contribute to neoplasia. Met, the hepatocyte growth factor (HGF) receptor, promotes a morphogenic program in epithelial cell lines in matrix cultures. Previous studies have identified Gab1, the major phosphorylated protein following Met activation, as important for the morphogenic response. Gab1 is a docking protein that couples the Met receptor with multiple signaling proteins, including phosphatidylinositol-3 kinase, phospholipase Cγ, the adapter protein Crk, and the tyrosine specific phosphatase SHP-2. HGF induces sustained phosphorylation of Gab1 and sustained activation of extracellular signal-regulated kinase (Erk) in epithelial Madin-Darby canine kidney cells. In contrast, epidermal growth factor fails to promote a morphogenic program and induces transient Gab1 phosphorylation and Erk activation. To elucidate the Gab1-dependent signals required for epithelial morphogenesis, we undertook a structure-function approach and demonstrate that association of Gab1 with the tyrosine phosphatase SHP-2 is required for sustained Erk activation and for epithelial morphogenesis downstream from the Met receptor. Epithelial cells expressing a Gab1 mutant protein unable to recruit SHP-2 elicit a transient activation of Erk in response to HGF. Moreover, SHP-2 catalytic activity is required, since the expression of a catalytically inactive SHP-2 mutant, C/S, abrogates sustained activation of Erk and epithelial morphogenesis by the Met receptor. These data identify SHP-2 as a positive modulator of Erk activity and epithelial morphogenesis downstream from the Met receptor.

scholarly journals Role of Phosphoinositide 3-Kinase and Endocytosis in Nerve Growth Factor-Induced Extracellular Signal-Regulated Kinase Activation via Ras and Rap1

2000 ◽  
Vol 20 (21) ◽  
pp. 8069-8083 ◽  
Author(s):  
Randall D. York ◽  
Derek C. Molliver ◽  
Savraj S. Grewal ◽  
Paula E. Stenberg ◽  
Edwin W. McCleskey ◽  
...  
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Map Kinase ◽  
Pc12 Cells ◽  
Erk Signaling ◽  
Nerve Growth ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Phosphoinositide 3 Kinase

ABSTRACT Neurotrophins promote multiple actions on neuronal cells including cell survival and differentiation. The best-studied neurotrophin, nerve growth factor (NGF), is a major survival factor in sympathetic and sensory neurons and promotes differentiation in a well-studied model system, PC12 cells. To mediate these actions, NGF binds to the TrkA receptor to trigger intracellular signaling cascades. Two kinases whose activities mediate these processes include the mitogen-activated protein (MAP) kinase (or extracellular signal-regulated kinase [ERK]) and phosphoinositide 3-kinase (PI3-K). To examine potential interactions between the ERK and PI3-K pathways, we studied the requirement of PI3-K for NGF activation of the ERK signaling cascade in dorsal root ganglion cells and PC12 cells. We show that PI3-K is required for TrkA internalization and participates in NGF signaling to ERKs via distinct actions on the small G proteins Ras and Rap1. In PC12 cells, NGF activates Ras and Rap1 to elicit the rapid and sustained activation of ERKs respectively. We show here that Rap1 activation requires both TrkA internalization and PI3-K, whereas Ras activation requires neither TrkA internalization nor PI3-K. Both inhibitors of PI3-K and inhibitors of endocytosis prevent GTP loading of Rap1 and block sustained ERK activation by NGF. PI3-K and endocytosis may also regulate ERK signaling at a second site downstream of Ras, since both rapid ERK activation and the Ras-dependent activation of the MAP kinase kinase kinase B-Raf are blocked by inhibition of either PI3-K or endocytosis. The results of this study suggest that PI3-K may be required for the signals initiated by TrkA internalization and demonstrate that specific endocytic events may distinguish ERK signaling via Rap1 and Ras.

Regulation of MEK/ERK pathway output by subcellular localization of B-Raf

2012 ◽  
Vol 40 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Catherine Andreadi ◽  
Catherine Noble ◽  
Bipin Patel ◽  
Hong Jin ◽  
Maria M. Aguilar Hernandez ◽  
...  
Keyword(s):  
Growth Factor ◽  
Subcellular Localization ◽  
Signalling Pathway ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Intracellular Signalling Pathway ◽  
Pathway Activation ◽  
Extracellular Signal ◽  
A Cell ◽  
Phase Entry

The strength and duration of intracellular signalling pathway activation is a key determinant of the biological outcome of cells in response to extracellular cues. This has been particularly elucidated for the Ras/Raf/MEK [mitogen-activated growth factor/ERK (extracellular-signal-regulated kinase) kinase]/ERK signalling pathway with a number of studies in fibroblasts showing that sustained ERK signalling is a requirement for S-phase entry, whereas transient ERK signalling does not have this capability. A major unanswered question, however, is how a cell can sustain ERK activation, particularly when ERK-specific phosphatases are transcriptionally up-regulated by the pathway itself. A major point of ERK regulation is at the level of Raf, and, to sustain ERK activation in the presence of ERK phosphatases, sustained Raf activation is a requirement. Three Raf proteins exist in mammals, and the activity of all three is induced following growth factor stimulation of cells, but only B-Raf activity is maintained at later time points. This observation points to B-Raf as a regulator of sustained ERK activation. In the present review, we consider evidence for a link between B-Raf and sustained ERK activation, focusing on a potential role for the subcellular localization of B-Raf in this key physiological event.

scholarly journals Kinetic and biochemical correlation between sustained p44ERK1 (44 kDa extracellular signal-regulated kinase 1) activation and lysophosphatidic acid-stimulated DNA synthesis in Rat-1 cells

1996 ◽  
Vol 320 (1) ◽  
pp. 237-245 ◽  
Author(s):  
Simon J. COOKOnyx ◽  
Frank McCORMICK
Keyword(s):  
Dna Synthesis ◽  
Pertussis Toxin ◽  
Lysophosphatidic Acid ◽  
Peak Response ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Herbimycin A ◽  
Extracellular Signal ◽  
Sustained Activation

Rat-1 fibroblasts were used to study the role of the sustained activation of extracellular signal-regulated kinase 1 (ERK1) in lysophosphatidic acid (LPA)-stimulated mitogenic signalling. Mitogenic doses of LPA, like serum, stimulated biphasic, sustained, ERK activation that persisted towards the G1/S boundary. The EC50 for LPA-stimulated ERK activation after 10 min, the time of peak response, was 2 orders of magnitude to the left of that for the sustained response after 3 h or that for DNA synthesis after 22 h, with the result that non-mitogenic doses stimulated a maximal peak response but no second phase. To complement these studies, we examined the role of different signal pathways in regulating the sustained and acute phases of ERK activation using defined biochemical inhibitors and mimetics. Activation of protein kinase C and Ca2+ fluxes played a minor and transient role in regulation of ERK1 activity by LPA in Rat-1 cells. Sustained ERK1 activation stimulated by LPA was completely inhibited by pertussis toxin, whereas the early peak response was only partly affected; this is correlated with the specific inhibition of LPA-stimulated DNA synthesis by pertussis toxin. The selective tyrosine kinase inhibitor herbimycin A completely inhibited sustained ERK1 activation by LPA but, again, the early phase of the response was only partially inhibited. In addition, low doses of staurosporine inhibited ERK1 activation by LPA. The effects of herbimycin A and staurosporine were selective for the response to LPA but did not affect that to epidermal growth factor. The results suggest a strong correlation between sustained ERK1 activation and DNA synthesis in LPA-stimulated Rat-1 cells. Furthermore, the two discrete phases of ERK activation by LPA are regulated by a combination of at least two different signalling pathways; the sustained activation of ERK1 in Rat-1 cells proceeds via a Gi- or Go-mediated pathway which may also involve a tyrosine kinase.

scholarly journals GP78 Cooperates with Dual-Specificity Phosphatase 1 To Stimulate Epidermal Growth Factor Receptor-Mediated Extracellular Signal-Regulated Kinase Signaling

2019 ◽  
Vol 39 (11) ◽  
Author(s):  
Dhong Hyo Kho ◽  
Mohammed Hafiz Uddin ◽  
Madhumita Chatterjee ◽  
Andreas Vogt ◽  
Avraham Raz ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Growth Factor Receptor ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Dual Specificity ◽  
Extracellular Signal ◽  
Epidermal Growth ◽  
Proliferation And Invasion

ABSTRACT GP78 is an autocrine motility factor (AMF) receptor (AMFR) with E3 ubiquitin ligase activity that plays a significant role in tumor cell proliferation, motility, and metastasis. Aberrant extracellular signal-regulated kinase (ERK) activation via receptor tyrosine kinases promotes tumor proliferation and invasion. The activation of GP78 leads to ERK activation, but its underlying mechanism is not fully understood. Here, we show that GP78 is required for epidermal growth factor receptor (EGFR)-mediated ERK activation. On one hand, GP78 interacts with and promotes the ubiquitination and subsequent degradation of dual-specificity phosphatase 1 (DUSP1), an endogenous negative regulator of mitogen-activated protein kinases (MAPKs), resulting in ERK activation. On the other hand, GP78 maintains the activation status of EGFR, as evidenced by the fact that EGF fails to induce EGFR phosphorylation in GP78-deficient cells. By the regulation of both EGFR and ERK activation, GP78 promotes cell proliferation, motility, and invasion. Therefore, this study identifies a previously unknown signaling pathway by which GP78 stimulates ERK activation via DUSP1 degradation to mediate EGFR-dependent cancer cell proliferation and invasion.

scholarly journals 5-Hydroxytryptamine4 Receptor Activation of the Extracellular Signal-regulated Kinase Pathway Depends on Src Activation but Not on G Protein or β-Arrestin Signaling

2007 ◽  
Vol 18 (6) ◽  
pp. 1979-1991 ◽  
Author(s):  
Gaël Barthet ◽  
Bérénice Framery ◽  
Florence Gaven ◽  
Lucie Pellissier ◽  
Eric Reiter ◽  
...  
Keyword(s):  
Receptor Activation ◽  
Erk Pathway ◽  
Independent Manner ◽  
Src Tyrosine Kinase ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Transient Activation ◽  
293 Cells ◽  
Extracellular Signal ◽  
Kinase Pathway

The 5-hydroxytryptamine4 (5-HT4) receptors have recently emerged as key modulators of learning, memory, and cognitive processes. In neurons, 5-hydroxytryptamine4 receptors (5-HT4Rs) activate cAMP production and protein kinase A (PKA); however, nothing is known about their ability to activate another key signaling pathway involved in learning and memory: the extracellular signal-regulated kinase (ERK) pathway. Here, we show that 5-HT4R stimulation, in primary neurons, produced a potent but transient activation of the ERK pathway. Surprisingly, this activation was mostly PKA independent. Similarly, using pharmacological, genetic, and molecular tools, we observed that 5-HT4Rs in human embryonic kidney 293 cells, activated the ERK pathway in a Gs/cAMP/PKA-independent manner. We also demonstrated that other classical G proteins (Gq/Gi/Go) and associated downstream messengers were not implicated in the 5-HT4R–activated ERK pathway. The 5-HT4R–mediated ERK activation seemed to be dependent on Src tyrosine kinase and yet totally independent of β-arrestin. Immunocytofluorescence revealed that ERK activation by 5-HT4R was restrained to the plasma membrane, whereas p-Src colocalized with the receptor and carried on even after endocytosis. This phenomenon may result from a tight interaction between 5-HT4R and p-Src detected by coimmunoprecipitation. Finally, we confirmed that the main route by which 5-HT4Rs activate ERKs in neurons was Src dependent. Thus, in addition to classical cAMP/PKA signaling pathways, 5-HT4Rs may use ERK pathways to control memory process.

scholarly journals Raf-1 Serine 338 Phosphorylation Plays a Key Role in Adhesion-Dependent Activation of Extracellular Signal-Regulated Kinase by Epidermal Growth Factor

2005 ◽  
Vol 25 (11) ◽  
pp. 4466-4475 ◽  
Author(s):  
Matthew L. Edin ◽  
Rudy L. Juliano
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Highly Active ◽  
Extracellular Signal ◽  
Tightly Coupled ◽  
Epidermal Growth ◽  
P21 Activated Kinase ◽  
Suspended Cells

ABSTRACT Activation of the extracellular signal-regulated kinase (ERK) 1/2 cascade by polypeptide growth factors is tightly coupled to adhesion to extracellular matrix in nontransformed cells. Raf-1, the initial kinase in this cascade, is intricately regulated by phosphorylation, localization, and molecular interactions. We investigated the complex interactions between Raf-1, protein kinase A (PKA), and p21-activated kinase (PAK) to determine their roles in the adhesion dependence of signaling from epidermal growth factor (EGF) to ERK. We conclude that Raf-1 phosphorylation on serine 338 (S338) is a critical step that is inhibited in suspended cells. Restoration of phosphorylation at S338, either by expression of highly active PAK or by expression of an S338 phospho-mimetic Raf-1 mutation, led to a partial rescue of ERK activation in suspended cells. Raf-1 inhibition in suspension was not due to excessive negative regulation on inhibitory sites S43 and S259, as these serines were largely dephosphorylated in suspended cells. Finally, strong phosphorylation of Raf-1 S338 provided resistance to PKA-mediated inhibition of ERK activation. Phosphorylation at Raf-1 S43 and S259 by PKA only weakly inhibited EGF activation of Raf-1 and ERK when cells maintained high Raf-1 S338 phosphorylation.

scholarly journals A novel role for FGF and extracellular signal–regulated kinase in gap junction–mediated intercellular communication in the lens

2001 ◽  
Vol 154 (1) ◽  
pp. 197-216 ◽  
Author(s):  
Anh-Chi N. Le ◽  
Linda S. Musil
Keyword(s):  
Growth Factor ◽  
Gap Junction ◽  
Intercellular Communication ◽  
Equatorial Region ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Junctional Coupling ◽  
Gap Junctional ◽  
Gap Junctional Coupling

Gap junction–mediated intercellular coupling is higher in the equatorial region of the lens than at either pole, a property believed to be essential for lens transparency. We show that fibroblast growth factor (FGF) upregulates gap junctional intercellular dye transfer in primary cultures of embryonic chick lens cells without detectably increasing either gap junction protein (connexin) synthesis or assembly. Insulin and insulin-like growth factor 1, as potent as FGF in inducing lens cell differentiation, had no effect on gap junctions. FGF induced sustained activation of extracellular signal–regulated kinase (ERK) in lens cells, an event necessary and sufficient to increase gap junctional coupling. We also identify vitreous humor as an in vivo source of an FGF-like intercellular communication-promoting activity and show that FGF-induced ERK activation in the intact lens is higher in the equatorial region than in polar and core fibers. These findings support a model in which regional differences in FGF signaling through the ERK pathway lead to the asymmetry in gap junctional coupling required for proper lens function. Our results also identify upregulation of intercellular communication as a new function for sustained ERK activation and change the current paradigm that ERKs only negatively regulate gap junction channel activity.

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