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Molecular and Cellular Biology, March 2000, p. 1626-1638, Vol. 20, No. 5
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

Akt Suppresses Apoptosis by Stimulating the Transactivation Potential of the RelA/p65 Subunit of NF-kappa B

Lee V. Madrid,1,2 Cun-Yu Wang,3 Denis C. Guttridge,1 Arndt J. G. Schottelius,1 Albert S. Baldwin Jr.,1,2,4 and Marty W. Mayo1,*

Lineberger Comprehensive Cancer Center,1 Curriculum in Genetics and Molecular Biology,2 and Department of Biology,4 University of North Carolina, Chapel Hill, North Carolina 27599, and The Laboratory of Molecular Signaling, Department of Biologic and Material Science, School of Dentistry, University of Michigan, Ann Arbor, Michigan 481093

Received 22 June 1999/Returned for modification 4 August 1999/Accepted 7 December 1999

It is well established that cell survival signals stimulated by growth factors, cytokines, and oncoproteins are initiated by phosphoinositide 3-kinase (PI3K)- and Akt-dependent signal transduction pathways. Oncogenic Ras, an upstream activator of Akt, requires NF-kappa B to initiate transformation, at least partially through the ability of NF-kappa B to suppress transformation-associated apoptosis. In this study, we show that oncogenic H-Ras requires PI3K and Akt to stimulate the transcriptional activity of NF-kappa B. Activated forms of H-Ras and MEKK stimulate signals that result in nuclear translocation and DNA binding of NF-kappa B as well as stimulation of the NF-kappa B transactivation potential. In contrast, activated PI3K or Akt stimulates NF-kappa B-dependent transcription by stimulating transactivation domain 1 of the p65 subunit rather than inducing NF-kappa B nuclear translocation via Ikappa B degradation. Inhibition of Ikappa B kinase (IKK), using an IKKbeta dominant negative protein, demonstrated that activated Akt requires IKK to efficiently stimulate the transactivation domain of the p65 subunit of NF-kappa B. Inhibition of endogenous Akt activity sensitized cells to H-Ras(V12)-induced apoptosis, which was associated with a loss of NF-kappa B transcriptional activity. Finally, Akt-transformed cells were shown to require NF-kappa B to suppress the ability of etoposide to induce apoptosis. Our work demonstrates that, unlike activated Ras, which can stimulate parallel pathways to activate both DNA binding and the transcriptional activity of NF-kappa B, Akt stimulates NF-kappa B predominantly by upregulating of the transactivation potential of p65.

* Corresponding author. Mailing address: Lineberger Comprehensive Cancer Center, Campus Box Number 7295, University of North Carolina, Chapel Hill, NC 27599. Phone: (919) 966-3884. Fax: (919) 966-0444.

Molecular and Cellular Biology, March 2000, p. 1626-1638, Vol. 20, No. 5
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.


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