Cargando…
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...
Autores principales: | , , , , , , , , , , , |
---|---|
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 |
_version_ | 1782189193396486144 |
---|---|
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. |
format | Text |
id | pubmed-2962498 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2010 |
publisher | American Society for Biochemistry and Molecular Biology |
record_format | MEDLINE/PubMed |
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 |
work_keys_str_mv | AT karasseksascha rashomologenrichedinbrainrhebenhancesapoptoticsignaling AT berghauscarsten rashomologenrichedinbrainrhebenhancesapoptoticsignaling AT schwartenmelanie rashomologenrichedinbrainrhebenhancesapoptoticsignaling AT goemanschristophg rashomologenrichedinbrainrhebenhancesapoptoticsignaling AT ohsenadine rashomologenrichedinbrainrhebenhancesapoptoticsignaling AT kockgerd rashomologenrichedinbrainrhebenhancesapoptoticsignaling AT jockerskatharina rashomologenrichedinbrainrhebenhancesapoptoticsignaling AT neumannsebastian rashomologenrichedinbrainrhebenhancesapoptoticsignaling AT gottfriedsebastian rashomologenrichedinbrainrhebenhancesapoptoticsignaling AT herrmannchristian rashomologenrichedinbrainrhebenhancesapoptoticsignaling AT heumannrolf rashomologenrichedinbrainrhebenhancesapoptoticsignaling AT stollraphael rashomologenrichedinbrainrhebenhancesapoptoticsignaling |