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.

scholarly journals Nerve Growth Factor Activation of the Extracellular Signal-Regulated Kinase Pathway Is Modulated by Ca2+and Calmodulin

2000 ◽  
Vol 20 (6) ◽  
pp. 1931-1946 ◽  
Author(s):  
Joaquim Egea ◽  
Carme Espinet ◽  
Rosa M. Soler ◽  
Sandra Peiró ◽  
Nativitat Rocamora ◽  
...  
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Pc12 Cells ◽  
Sympathetic Neurons ◽  
Moderate Increase ◽  
Dependent Manner ◽  
Nerve Growth ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Kinase Pathway

ABSTRACT Nerve growth factor is a member of the neurotrophin family of trophic factors that have been reported to be essential for the survival and development of sympathetic neurons and a subset of sensory neurons. Nerve growth factor exerts its effects mainly by interaction with the specific receptor TrkA, which leads to the activation of several intracellular signaling pathways. Once activated, TrkA also allows for a rapid and moderate increase in intracellular calcium levels, which would contribute to the effects triggered by nerve growth factor in neurons. In this report, we analyzed the relationship of calcium to the activation of the Ras/extracellular signal-regulated kinase pathway in PC12 cells. We observed that calcium and calmodulin are both necessary for the acute activation of extracellular signal-regulated kinases after TrkA stimulation. We analyzed the elements of the pathway that lead to this activation, and we observed that calmodulin antagonists completely block the initial Raf-1 activation without affecting the function of upstream elements, such as Ras, Grb2, Shc, and Trk. We have broadened our study to other stimuli that activate extracellular signal-regulated kinases through tyrosine kinase receptors, and we have observed that calmodulin also modulates the activation of such kinases after epidermal growth factor receptor stimulation in PC12 cells and after TrkB stimulation in cultured chicken embryo motoneurons. Calmodulin seems to regulate the full activation of Raf-1 after Ras activation, since functional Ras is necessary for Raf-1 activation after nerve growth factor stimulation and calmodulin-Sepharose is able to precipitate Raf-1 in a calcium-dependent manner.

scholarly journals Nerve Growth Factor Activates Extracellular Signal-Regulated Kinase and p38 Mitogen-Activated Protein Kinase Pathways To Stimulate CREB Serine 133 Phosphorylation

1998 ◽  
Vol 18 (4) ◽  
pp. 1946-1955 ◽  
Author(s):  
Jun Xing ◽  
Jon M. Kornhauser ◽  
Zhengui Xia ◽  
Elizabeth A. Thiele ◽  
Michael E. Greenberg
Keyword(s):  
Transcription Factor ◽  
Nerve Growth Factor ◽  
Growth Factor ◽  
Protein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Nerve Growth ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Ribosomal S6 Kinase

ABSTRACT The mechanisms by which growth factor-induced signals are propagated to the nucleus, leading to the activation of the transcription factor CREB, have been characterized. Nerve growth factor (NGF) was found to activate multiple signaling pathways that mediate the phosphorylation of CREB at the critical regulatory site, serine 133 (Ser-133). NGF activates the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinases (MAPKs), which in turn activate the pp90 ribosomal S6 kinase (RSK) family of Ser/Thr kinases, all three members of which were found to catalyze CREB Ser-133 phosphorylation in vitro and in vivo. In addition to the ERK/RSK pathway, we found that NGF activated the p38 MAPK and its downstream effector, MAPK-activated protein kinase 2 (MAPKAP kinase 2), resulting in phosphorylation of CREB at Ser-133. Inhibition of either the ERK/RSK or the p38/MAPKAP kinase 2 pathway only partially blocked NGF-induced CREB Ser-133 phosphorylation, suggesting that either pathway alone is sufficient for coupling the NGF signal to CREB activation. However, inhibition of both the ERK/RSK and the p38/MAPKAP kinase 2 pathways completely abolished NGF-induced CREB Ser-133 phosphorylation. These findings indicate that NGF activates two distinct MAPK pathways, both of which contribute to the phosphorylation of the transcription factor CREB and the activation of immediate-early genes.

scholarly journals Nitric Oxide Synthase Inhibitors Modulate Nerve-Growth-Factor Mediated Activation of Akt

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Cheryl L. Cragg ◽  
Janet C. MacKinnon ◽  
Bettina E. Kalisch
Keyword(s):  
Nitric Oxide ◽  
Nerve Growth Factor ◽  
Growth Factor ◽  
Map Kinase ◽  
Pc12 Cells ◽  
Cell Lines ◽  
Nerve Growth ◽  
Akt Phosphorylation ◽  
Map Kinase Pathway ◽  
Kinase Pathway

Nitric oxide (NO) modulates nerve-growth-factor- (NGF-) mediated signaling and gene expression. In the present paper, the role of NO in NGF-mediated Akt activation in PC12 and IMR32 cells was investigated. Cells were treated with NGF (50 ng/mL) in the presence or absence of NO synthase (NOS) inhibitors and Akt phosphorylation assessed by western blot analysis. In both cell lines, Akt was phosphorylated within 15 min of NGF treatment. In PC12 cells, this level of phosphorylation was sustained for 60 min, while in IMR32 cells, the activation decreased after 30 min of NGF treatment. The nonselective NOS inhibitor Nω-nitro-L-arginine methylester (L-NAME; 20 mM) had no effect on NGF-mediated Akt phosphorylation in PC12 cells but in combination with NGF, the iNOS selective inhibitor s-methylisothiourea (S-MIU; 2.0 mM) maintained Akt phosphorylation up to 2 h. In IMR32 cells, both L-NAME and S-MIU prolonged the activation of Akt. Pretreatment with 50 μM U0126, a MAP kinase pathway inhibitor, also increased the activation of Akt in both cell lines. These data suggest that NO modulates the duration of phosphorylation of Akt in response to NGF and that this effect may, in part, be mediated by the effects of NO on the Ras-MAP kinase pathway.

scholarly journals Essential Role for Phospholipase D2 Activation Downstream of ERK MAP Kinase in Nerve Growth Factor-stimulated Neurite Outgrowth from PC12 Cells

2004 ◽  
Vol 279 (36) ◽  
pp. 37870-37877 ◽  
Author(s):  
Hiroshi Watanabe ◽  
Takeaki Yokozeki ◽  
Masakazu Yamazaki ◽  
Hideyuki Miyazaki ◽  
Takehiko Sasaki ◽  
...  
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Map Kinase ◽  
Neurite Outgrowth ◽  
Pc12 Cells ◽  
Essential Role ◽  
Nerve Growth ◽  
Phospholipase D2

AntioxidantN-Acetylcysteine Blocks Nerve Growth Factor-Induced H2O2/ERK Signaling in PC12 Cells

2005 ◽  
Vol 1042 (1) ◽  
pp. 325-337 ◽  
Author(s):  
LIANG-YO YANG ◽  
WUN-CHANG KO ◽  
CHUN-MAO LIN ◽  
JIA-WEI LIN ◽  
JEN-CHINE WU ◽  
...  
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Pc12 Cells ◽  
Erk Signaling ◽  
Nerve Growth

The mitogen-activated protein kinase cascade is activated by B-Raf in response to nerve growth factor through interaction with p21ras

1994 ◽  
Vol 14 (10) ◽  
pp. 6944-6953
Author(s):  
R K Jaiswal ◽  
S A Moodie ◽  
A Wolfman ◽  
G E Landreth
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Map Kinase ◽  
Pc12 Cells ◽  
Mitogen Activated Protein Kinase ◽  
Stable Complex ◽  
Nerve Growth ◽  
Map Kinase Cascade ◽  
Mitogen Activated Protein ◽  
Kinase Cascade

Nerve growth factor (NGF) activates the mitogen-activated protein (MAP) kinase cascade through a p21ras-dependent signal transduction pathway in PC12 cells. The linkage between p21ras and MEK1 was investigated to identify those elements which participate in the regulation of MEK1 activity. We have screened for MEK activators using a coupled assay in which the MAP kinase cascade has been reconstituted in vitro. We report that we have detected a single NGF-stimulated MEK-activating activity which has been identified as B-Raf. PC12 cells express both B-Raf and c-Raf1; however, the MEK-activating activity was found only in fractions containing B-Raf. c-Raf1-containing fractions did not exhibit a MEK-activating activity. Gel filtration analysis revealed that the B-Raf eluted with an apparent M(r) of 250,000 to 300,000, indicating that it is present within a stable complex with other unidentified proteins. Immunoprecipitation with B-Raf-specific antisera quantitatively precipitated all MEK activator activity from these fractions. We also demonstrate that B-Raf, as well as c-Raf1, directly interacted with activated p21ras immobilized on silica beads. NGF treatment of the cells had no effect on the ability of B-Raf or c-Raf1 to bind to activated p21ras. These data indicate that this interaction was not dependent upon the activation state of these enzymes; however, MEK kinase activity was found to be associated with p21ras following incubation with NGF-treated samples at levels higher than those obtained from unstimulated cells. These data provide direct evidence that NGF-stimulated B-Raf is responsible for the activation of the MAP kinase cascade in PC12 cells, whereas c-Raf1 activity was not found to function within this pathway.

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