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Feedback activation of neurofibromin terminates growth factor-induced Ras activation.

Overview of attention for article published in Cell Communication and Signaling, January 2016
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Title
Feedback activation of neurofibromin terminates growth factor-induced Ras activation.
Published in
Cell Communication and Signaling, January 2016
DOI 10.1186/s12964-016-0128-z
Pubmed ID
Authors

Hennig, Anne, Markwart, Robby, Wolff, Katharina, Schubert, Katja, Cui, Yan, Prior, Ian A, Esparza-Franco, Manuel A, Ladds, Graham, Rubio, Ignacio, Anne Hennig, Robby Markwart, Katharina Wolff, Katja Schubert, Yan Cui, Ian A. Prior, Manuel A. Esparza-Franco, Graham Ladds, Ignacio Rubio

Abstract

Growth factors induce a characteristically short-lived Ras activation in cells emerging from quiescence. Extensive work has shown that transient as opposed to sustained Ras activation is critical for the induction of mitogenic programs. Mitogen-induced accumulation of active Ras-GTP results from increased nucleotide exchange driven by the nucleotide exchange factor Sos. In contrast, the mechanism accounting for signal termination and prompt restoration of basal Ras-GTP levels is unclear, but has been inferred to involve feedback inhibition of Sos. Remarkably, how GTP-hydrolase activating proteins (GAPs) participate in controlling the rise and fall of Ras-GTP levels is unknown. Monitoring nucleotide exchange of Ras in permeabilized cells we find, unexpectedly, that the decline of growth factor-induced Ras-GTP levels proceeds in the presence of unabated high nucleotide exchange, pointing to GAP activation as a major mechanism of signal termination. Experiments with non-hydrolysable GTP analogues and mathematical modeling confirmed and rationalized the presence of high GAP activity as Ras-GTP levels decline in a background of high nucleotide exchange. Using pharmacological and genetic approaches we document a raised activity of the neurofibromatosis type I tumor suppressor Ras-GAP neurofibromin and an involvement of Rsk1 and Rsk2 in the down-regulation of Ras-GTP levels. Our findings show that, in addition to feedback inhibition of Sos, feedback stimulation of the RasGAP neurofibromin enforces termination of the Ras signal in the context of growth-factor signaling. These findings ascribe a precise role to neurofibromin in growth factor-dependent control of Ras activity and illustrate how, by engaging Ras-GAP activity, mitogen-challenged cells play safe to ensure a timely termination of the Ras signal irrespectively of the reigning rate of nucleotide exchange.

Mendeley readers

The data shown below were compiled from readership statistics for 30 Mendeley readers of this research output. Click here to see the associated Mendeley record.

Geographical breakdown

Country Count As %
Unknown 30 100%

Demographic breakdown

Readers by professional status Count As %
Student > Ph. D. Student 9 30%
Student > Master 7 23%
Researcher 6 20%
Student > Doctoral Student 2 7%
Student > Bachelor 2 7%
Other 1 3%
Unknown 3 10%
Readers by discipline Count As %
Biochemistry, Genetics and Molecular Biology 10 33%
Agricultural and Biological Sciences 9 30%
Medicine and Dentistry 4 13%
Immunology and Microbiology 1 3%
Pharmacology, Toxicology and Pharmaceutical Science 1 3%
Other 2 7%
Unknown 3 10%