期刊
MOLECULAR AND CELLULAR BIOLOGY
卷 20, 期 5, 页码 1626-1638出版社
AMER SOC MICROBIOLOGY
DOI: 10.1128/MCB.20.5.1626-1638.2000
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资金
- NATIONAL CANCER INSTITUTE [R01CA072771, R01CA075080] Funding Source: NIH RePORTER
- NCI NIH HHS [R01 CA075080, CA75080, CA72771] Funding Source: Medline
- PHS HHS [K0178595] Funding Source: Medline
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 I kappa B degradation. Inhibition of I kappa B kinase (IKK), using an IKK beta 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.
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