This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services E-mail this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kuznetsov, A. V. Articles by Troppmair, J. Search for Related Content PubMed PubMed Citation Articles by Kuznetsov, A. V. Articles by Troppmair, J.

 Previous Article  |  Next Article 

Molecular and Cellular Biology, April 2008, p. 2304-2313, Vol. 28, No. 7
0270-7306/08/$08.00+0     doi:10.1128/MCB.00683-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Survival Signaling by C-RAF: Mitochondrial Reactive Oxygen Species and Ca²⁺ Are Critical Targets

Andrey V. Kuznetsov,^1, Julija Smigelskaite,^1, Christine Doblander,¹ Manickam Janakiraman,^1, Martin Hermann,² Martin Wurm,² Stefan F. Scheidl,¹ Robert Sucher,¹ Andrea Deutschmann,² and Jakob Troppmair^1*

Daniel Swarovski Research Laboratory,¹ KMT Laboratory, Department of General and Transplant Surgery, Innsbruck Medical University, 6020 Innsbruck, Austria²

Received 19 April 2007/ Returned for modification 23 July 2007/ Accepted 26 December 2007

Survival signaling by RAF occurs through largely unknown mechanisms. Here we provide evidence for the first time that RAF controls cell survival by maintaining permissive levels of mitochondrial reactive oxygen species (ROS) and Ca²⁺. Interleukin-3 (IL-3) withdrawal from 32D cells resulted in ROS production, which was suppressed by activated C-RAF. Oncogenic C-RAF decreased the percentage of apoptotic cells following treatment with staurosporine or the oxidative stress-inducing agent tert-butyl hydroperoxide. However, it was also the case that in parental 32D cells growing in the presence of IL-3, inhibition of RAF signaling resulted in elevated mitochondrial ROS and Ca²⁺ levels. Cell death is preceded by a ROS-dependent increase in mitochondrial Ca²⁺, which was absent from cells expressing transforming C-RAF. Prevention of mitochondrial Ca²⁺ overload after IL-3 deprivation increased cell viability. MEK was essential for the mitochondrial effects of RAF. In summary, our data show that survival control by C-RAF involves controlling ROS production, which otherwise perturbs mitochondrial Ca²⁺ homeostasis.

---

* Corresponding author. Mailing address: Daniel Swarovski Research Laboratory, Department of General and Transplant Surgery, Innsbruck Medical University, Innrain 66, 6020 Innsbruck, Austria. Phone: 43 512 504 24624. Fax: 43 512 504 24625. E-mail: jakob.troppmair{at}i-med.ac.at

Published ahead of print on 22 January 2008.

These authors contributed equally to this work.

Present address: Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.

---

Molecular and Cellular Biology, April 2008, p. 2304-2313, Vol. 28, No. 7
0270-7306/08/$08.00+0     doi:10.1128/MCB.00683-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Lampiasi, N., Azzolina, A., D'Alessandro, N., Umezawa, K., McCubrey, J. A., Montalto, G., Cervello, M. (2009). Antitumor Effects of Dehydroxymethylepoxyquinomicin, a Novel Nuclear Factor-{kappa}B Inhibitor, in Human Liver Cancer Cells Are Mediated through a Reactive Oxygen Species-Dependent Mechanism. Mol. Pharmacol. 76: 290-300 [Abstract] [Full Text]