Ras palmitoylation is necessary for N-Ras activation and signal propagation in growth factor signalling

2013 ◽  
Vol 454 (2) ◽  
pp. 323-332 ◽  
Author(s):  
Shu-Ping Song ◽  
Anne Hennig ◽  
Katja Schubert ◽  
Robby Markwart ◽  
Philipp Schmidt ◽  
...  
Keyword(s):  
Growth Factor ◽  
Signal Propagation ◽  
Dominant Negative ◽  
Post Translational Modifications ◽  
Ras Gtpases ◽  
Ras Activation ◽  
Growth Factor Signalling ◽  
Mitogenic Signalling ◽  
Epidermal Growth

Ras GTPases undergo post-translational modifications that govern their subcellular trafficking and localization. In particular, palmitoylation of the Golgi tags N-Ras and H-Ras for exocytotic transport and residency at the PM (plasma membrane). Following depalmitoylation, PM-Ras redistributes to all subcellular membranes causing an accumulation of palmitate-free Ras at endomembranes, including the Golgi and endoplasmic reticulum. Palmitoylation is unanimously regarded as a critical modification at the crossroads of Ras activity and trafficking control, but its precise relevance to native wild-type Ras function in growth factor signalling is unknown. We show in the present study by use of palmitoylation-deficient N-Ras mutants and via the analysis of palmitate content of agonist-activated GTP-loaded N-Ras that only palmitoylated N-Ras becomes activated by agonists. In line with an essential role of palmitoylation in Ras activation, dominant-negative RasS17N loses its blocking potency if rendered devoid of palmitoylation. Live-cell Ras–GTP imaging shows that N-Ras activation proceeds only at the PM, consistent with activated N-Ras–GTP being palmitoylated. Finally, palmitoylation-deficient N-Ras does not sustain EGF (epidermal growth factor) or serum-elicited mitogenic signalling, confirming that palmitoylation is essential for signal transduction by N-Ras. These findings document that N-Ras activation proceeds at the PM and suggest that depalmitoylation, by removing Ras from the PM, may contribute to the shutdown of Ras signalling.

scholarly journals Gab1 and SHP-2 promote Ras/MAPK regulation of epidermal growth and differentiation

2002 ◽  
Vol 159 (1) ◽  
pp. 103-112 ◽  
Author(s):  
Ti Cai ◽  
Keigo Nishida ◽  
Toshio Hirano ◽  
Paul A. Khavari
Keyword(s):  
Epidermal Cell ◽  
Mapk Signaling ◽  
Dominant Negative ◽  
Mapk Activity ◽  
Ras Activation ◽  
Proliferation And Differentiation ◽  
Epidermal Proliferation ◽  
Epidermal Growth ◽  
Docking Protein

În epidermis, Ras can influence proliferation and differentiation; however, regulators of epidermal Ras function are not fully characterized, and Ras effects on growth and differentiation are controversial. EGF induced Ras activation in epidermal cells along with phosphorylation of the multisubstrate docking protein Gab1 and its binding to SHP-2. Expression of mutant Gab1Y627F deficient in SHP-2 binding or dominant-negative SHP-2C459S reduced basal levels of active Ras and downstream MAPK proteins and initiated differentiation. Differentiation triggered by both Gab1Y627F and SHP-2C459S could be blocked by coexpression of active Ras, consistent with Gab1 and SHP-2 action upstream of Ras in this process. To study the role of Gab1 and SHP-2 in tissue, we generated human epidermis overexpressing active Gab1 and SHP-2. Both proteins stimulated proliferation. In contrast, Gab1Y627F and SHP-2C459S inhibited epidermal proliferation and enhanced differentiation. Consistent with a role for Gab1 and SHP-2 in sustaining epidermal Ras/MAPK activity, Gab1−/− murine epidermis displayed lower levels of active Ras and MAPK with postnatal Gab1−/− epidermis, demonstrating the hypoplasia and enhanced differentiation seen previously with transgenic epidermal Ras blockade. These data provide support for a Ras role in promoting epidermal proliferation and opposing differentiation and indicate that Gab1 and SHP-2 promote the undifferentiated epidermal cell state by facilitating Ras/MAPK signaling.

scholarly journals Epidermal growth factor and Ras regulate gene expression in GH4 pituitary cells by separate, antagonistic signal transduction pathways.

1995 ◽  
Vol 15 (12) ◽  
pp. 6777-6784 ◽  
Author(s):  
C A Pickett ◽  
A Gutierrez-Hartmann
Keyword(s):  
Signal Transduction ◽  
Transcription Factors ◽  
Growth Factor ◽  
Map Kinase ◽  
Dominant Negative ◽  
Neuroendocrine Cells ◽  
Dependent Manner ◽  
Epidermal Growth ◽  
Dose Dependent

We have previously demonstrated that epidermal growth factor (EGF) produces activation of the rat prolactin (rPRL) promoter in GH4 neuroendocrine cells via a Ras-independent mechanism. This Ras independence of the EGF response appears to be cell rather than promoter specific. Oncogenic Ras also produces activation of the rPRL promoter when transfected into GH4 cells and requires the sequential activation of Raf kinase, mitogen-activated protein (MAP) kinase, and c-Ets-1/GHF-1 to mediate this response. In these studies, we have investigated the interaction between EGF and Ras in stimulating rPRL promoter activity and the role of Raf and MAP kinases in mediating the EGF response. We have also examined the role of several transcription factors and used various promoter mutants of the rPRL gene in order to better define the trans- and cis-acting components of the EGF response. EGF treatment of GH4 cells inhibits activation of the rPRL promoter produced by transfection of V12Ras from 24- to 4-fold in an EGF dose-dependent manner. This antagonistic effect of EGF and Ras is mutual in that transfection of V12Ras also blocks EGF-induced activation of the rPRL promoter in a Ras dose-dependent manner, from 5.5- to 1.6-fold. Transfection of a plasmid encoding the dominant-negative Raf C4 blocks Ras-induced activation by 66% but fails to inhibit EGF-mediated activation of the rPRL promoter. Similarly, transfection of a construct encoding an inhibitory form of MAP kinase decreases the Ras response by 50% but does not inhibit the EGF response. Previous studies have demonstrated that c-Ets-1 is necessary and that GHF-1 acts synergistically with c-Ets-1 in the Ras response of the rPRL promoter. In contrast, overexpression of neither c-Ets-1 nor GHF-1 enhanced EGF-mediated activation of the rPRL promoter, and dominant-negative forms of these transcription factors failed to inhibit the EGF response. Using 5' deletion and site-specific mutations, we have mapped the EGF response to two regions on the proximal rPRL promoter. One region maps between -255 and -212, near the Ras response element, and a second maps between -125 and -54. The latter region appears to involve footprint 2, a previously identified repressor site on the rPRL promoter. Neither footprint 1 nor 3, known GHF-1 binding sites, appears to be crucial to RGF-mediated rPRL promoter activation. The results of these studies indicate that in GH4 neuroendocrine cells, rPRL gene regulation by EGF is mediated by a signal transduction pathway that is separate and antagonistic to the Ras pathway. Hence, the functional role of the Ras/Raf/MAP kinase pathway in mediating transcriptional responses to EGF and other receptor tyrosine kinase may differ in highly specialized cell types.

Role of heterotrimeric G-proteins in epidermal growth factor signalling

1995 ◽  
Vol 7 (4) ◽  
pp. 303-311 ◽  
Author(s):  
Ignasi Ramírez ◽  
Francesc Tebar ◽  
Montserrat Grau ◽  
Maria Soley
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
G Proteins ◽  
Heterotrimeric G Proteins ◽  
Growth Factor Signalling ◽  
Epidermal Growth

Ras palmitoylation is necessary for N-Ras activation and signal propagation in growth factor signalling

2013 ◽  
Vol 455 (1) ◽  
pp. 131-131 ◽  
Author(s):  
S.-P. Song ◽  
A. Hennig ◽  
K. Schubert ◽  
R. Markwart ◽  
P. Schmidt ◽  
...  
Keyword(s):  
Growth Factor ◽  
Signal Propagation ◽  
Ras Activation ◽  
Growth Factor Signalling

scholarly journals Differential Pathways of Angiotensin II-Induced Extracellularly Regulated Kinase 1/2 Phosphorylation in Specific Cell Types: Role of Heparin-Binding Epidermal Growth Factor

2004 ◽  
Vol 18 (8) ◽  
pp. 2035-2048 ◽  
Author(s):  
Bukhtiar H. Shah ◽  
Akin Yesilkaya ◽  
J. Alberto Olivares-Reyes ◽  
Hung-Dar Chen ◽  
László Hunyady ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cell Types ◽  
Specific Cell ◽  
Heparin Binding ◽  
Epidermal Growth

Interaction of Growth Hormone-Releasing Factor and Somatostatin on Ulcer Healing and Mucosal Growth in Rats: Role of Gastrin and Epidermal Growth Factor

Digestion ◽  
1988 ◽  
Vol 41 (3) ◽  
pp. 121-128 ◽  
Author(s):  
S.J. Konturek ◽  
T. Brzozowski ◽  
A. Dembinski ◽  
Z. Warzecha ◽  
P.K. Konturek ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Ulcer Healing ◽  
Growth Hormone Releasing Factor ◽  
Epidermal Growth ◽  
Mucosal Growth
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