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Ras Homolog Enriched in Brain (Rheb) Enhances Apoptotic Signaling

Rheb is a homolog of Ras GTPase that regulates cell growth, proliferation, and regeneration via mammalian target of rapamycin (mTOR). Because of the well established potential of activated Ras to promote survival, we sought to investigate the ability of Rheb signaling to phenocopy Ras. We found that...

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Autores principales: Karassek, Sascha, Berghaus, Carsten, Schwarten, Melanie, Goemans, Christoph G., Ohse, Nadine, Kock, Gerd, Jockers, Katharina, Neumann, Sebastian, Gottfried, Sebastian, Herrmann, Christian, Heumann, Rolf, Stoll, Raphael
Formato: Texto
Lenguaje:English
Publicado: American Society for Biochemistry and Molecular Biology 2010
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2962498/
https://www.ncbi.nlm.nih.gov/pubmed/20685651
http://dx.doi.org/10.1074/jbc.M109.095968
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author Karassek, Sascha
Berghaus, Carsten
Schwarten, Melanie
Goemans, Christoph G.
Ohse, Nadine
Kock, Gerd
Jockers, Katharina
Neumann, Sebastian
Gottfried, Sebastian
Herrmann, Christian
Heumann, Rolf
Stoll, Raphael
author_facet Karassek, Sascha
Berghaus, Carsten
Schwarten, Melanie
Goemans, Christoph G.
Ohse, Nadine
Kock, Gerd
Jockers, Katharina
Neumann, Sebastian
Gottfried, Sebastian
Herrmann, Christian
Heumann, Rolf
Stoll, Raphael
author_sort Karassek, Sascha
collection PubMed
description Rheb is a homolog of Ras GTPase that regulates cell growth, proliferation, and regeneration via mammalian target of rapamycin (mTOR). Because of the well established potential of activated Ras to promote survival, we sought to investigate the ability of Rheb signaling to phenocopy Ras. We found that overexpression of lipid-anchored Rheb enhanced the apoptotic effects induced by UV light, TNFα, or tunicamycin in an mTOR complex 1 (mTORC1)-dependent manner. Knocking down endogenous Rheb or applying rapamycin led to partial protection, identifying Rheb as a mediator of cell death. Ras and c-Raf kinase opposed the apoptotic effects induced by UV light or TNFα but did not prevent Rheb-mediated apoptosis. To gain structural insight into the signaling mechanisms, we determined the structure of Rheb-GDP by NMR. The complex adopts the typical canonical fold of RasGTPases and displays the characteristic GDP-dependent picosecond to nanosecond backbone dynamics of the switch I and switch II regions. NMR revealed Ras effector-like binding of activated Rheb to the c-Raf-Ras-binding domain (RBD), but the affinity was 1000-fold lower than the Ras/RBD interaction, suggesting a lack of functional interaction. shRNA-mediated knockdown of apoptosis signal-regulating kinase 1 (ASK-1) strongly reduced UV or TNFα-induced apoptosis and suppressed enhancement by Rheb overexpression. In conclusion, Rheb-mTOR activation not only promotes normal cell growth but also enhances apoptosis in response to diverse toxic stimuli via an ASK-1-mediated mechanism. Pharmacological regulation of the Rheb/mTORC1 pathway using rapamycin should take the presence of cellular stress into consideration, as this may have clinical implications.
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spelling pubmed-29624982010-11-03 Ras Homolog Enriched in Brain (Rheb) Enhances Apoptotic Signaling Karassek, Sascha Berghaus, Carsten Schwarten, Melanie Goemans, Christoph G. Ohse, Nadine Kock, Gerd Jockers, Katharina Neumann, Sebastian Gottfried, Sebastian Herrmann, Christian Heumann, Rolf Stoll, Raphael J Biol Chem Cell Biology Rheb is a homolog of Ras GTPase that regulates cell growth, proliferation, and regeneration via mammalian target of rapamycin (mTOR). Because of the well established potential of activated Ras to promote survival, we sought to investigate the ability of Rheb signaling to phenocopy Ras. We found that overexpression of lipid-anchored Rheb enhanced the apoptotic effects induced by UV light, TNFα, or tunicamycin in an mTOR complex 1 (mTORC1)-dependent manner. Knocking down endogenous Rheb or applying rapamycin led to partial protection, identifying Rheb as a mediator of cell death. Ras and c-Raf kinase opposed the apoptotic effects induced by UV light or TNFα but did not prevent Rheb-mediated apoptosis. To gain structural insight into the signaling mechanisms, we determined the structure of Rheb-GDP by NMR. The complex adopts the typical canonical fold of RasGTPases and displays the characteristic GDP-dependent picosecond to nanosecond backbone dynamics of the switch I and switch II regions. NMR revealed Ras effector-like binding of activated Rheb to the c-Raf-Ras-binding domain (RBD), but the affinity was 1000-fold lower than the Ras/RBD interaction, suggesting a lack of functional interaction. shRNA-mediated knockdown of apoptosis signal-regulating kinase 1 (ASK-1) strongly reduced UV or TNFα-induced apoptosis and suppressed enhancement by Rheb overexpression. In conclusion, Rheb-mTOR activation not only promotes normal cell growth but also enhances apoptosis in response to diverse toxic stimuli via an ASK-1-mediated mechanism. Pharmacological regulation of the Rheb/mTORC1 pathway using rapamycin should take the presence of cellular stress into consideration, as this may have clinical implications. American Society for Biochemistry and Molecular Biology 2010-10-29 2010-08-04 /pmc/articles/PMC2962498/ /pubmed/20685651 http://dx.doi.org/10.1074/jbc.M109.095968 Text en © 2010 by The American Society for Biochemistry and Molecular Biology, Inc. Author's Choice—Final version full access. Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) applies to Author Choice Articles
spellingShingle Cell Biology
Karassek, Sascha
Berghaus, Carsten
Schwarten, Melanie
Goemans, Christoph G.
Ohse, Nadine
Kock, Gerd
Jockers, Katharina
Neumann, Sebastian
Gottfried, Sebastian
Herrmann, Christian
Heumann, Rolf
Stoll, Raphael
Ras Homolog Enriched in Brain (Rheb) Enhances Apoptotic Signaling
title Ras Homolog Enriched in Brain (Rheb) Enhances Apoptotic Signaling
title_full Ras Homolog Enriched in Brain (Rheb) Enhances Apoptotic Signaling
title_fullStr Ras Homolog Enriched in Brain (Rheb) Enhances Apoptotic Signaling
title_full_unstemmed Ras Homolog Enriched in Brain (Rheb) Enhances Apoptotic Signaling
title_short Ras Homolog Enriched in Brain (Rheb) Enhances Apoptotic Signaling
title_sort ras homolog enriched in brain (rheb) enhances apoptotic signaling
topic Cell Biology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2962498/
https://www.ncbi.nlm.nih.gov/pubmed/20685651
http://dx.doi.org/10.1074/jbc.M109.095968
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