Cell type-specific expression of the IkappaB kinases determines the significance of phosphatidylinositol 3-kinase/Akt signaling to NF-kappa B activation.
J Biol Chem
; 279(3): 1615-20, 2004 Jan 16.
Article
en En
| MEDLINE
| ID: mdl-14585846
ABSTRACT
Phosphatidylinositol (PI) 3-kinase/Akt signaling activates NF-kappa B through pleiotropic, cell type-specific mechanisms. This study investigated the significance of PI 3-kinase/Akt signaling to tumor necrosis factor (TNF)-induced NF-kappa B activation in transformed, immortalized, and primary cells. Pharmacological inhibition of PI 3-kinase blocked TNF-induced NF-kappa B DNA binding in the 293 line of embryonic kidney cells, partially affected binding in MCF-7 breast cancer cells, HeLa and ME-180 cervical carcinoma cells, and NIH 3T3 cells but was without significant effect in H1299 and human umbilical vein endothelial cells, cell types in which TNF activated Akt. NF-kappa B is retained in the cytoplasm by inhibitory proteins, I kappa Bs, which are phosphorylated and targeted for degradation by I kappa B kinases (IKK alpha and IKK beta). Expression and the ratios of IKK alpha and IKK beta, which homo- and heterodimerize, varied among cell types. Cells with a high proportion of IKK alpha (the IKK kinase activated by Akt) to IKK beta were most sensitive to PI 3-kinase inhibitors. Consequently, transient expression of IKK beta diminished the capacity of the inhibitors to block NF-kappa B DNA binding in 293 cells. Also, inhibitors of PI 3-kinase blocked NF-kappa B DNA binding in Ikk beta-/- but not Ikk alpha-/- or wild-type cells in which the ratio of IKK alpha to IKK beta is low. Thus, noncoordinate expression of I kappa B kinases plays a role in determining the cell type-specific role of Akt in NF-kappa B activation.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
FN-kappa B
/
Proteínas Proto-Oncogénicas
/
Proteínas Serina-Treonina Quinasas
/
Fosfatidilinositol 3-Quinasas
Límite:
Animals
/
Humans
Idioma:
En
Revista:
J Biol Chem
Año:
2004
Tipo del documento:
Article
País de afiliación:
Estados Unidos