Thursday, October 25, 2007

NF-kappa B y ciclo celular

Este es un nuevo articulo muy interesante. Aunque ya se sabia que NF-kappa B algo tenia que ver con el ciclo celular (entre otros ver 'Int J Biochem Cell Biol.Tissue inhibitor of metalloproteinases-2 growth-stimulatory activity is mediated by nuclear factor-kappa B in A549 lung epithelial cells.Lizárraga F, Maldonado V, Meléndez-Zajgla J. ) este es uno de los mecanismos empleados para tal efecto.



A cell cycle regulatory network controlling NF-kappaB subunit activity and function
EMBO J advance online publication




Abstract
Aberrantly active NF-kappaB complexes can contribute to tumorigenesis by regulating genes that promote the growth and survival of cancer cells. We have investigated NF-kappaB during the cell cycle and find that its ability to regulate the G1-phase expression of key proto-oncogenes is subject to regulation by the integrated activity of IkappaB kinase (IKK)alpha, IKKbeta, Akt and Chk1. The coordinated binding of NF-kappaB subunits to the Cyclin D1, c-Myc and Skp2 promoters is dynamic with distinct changes in promoter occupancy and RelA(p65) phosphorylation occurring through G1, S and G2 phases, concomitant with a switch from coactivator to corepressor recruitment. Akt activity is required for IKK-dependent phosphorylation of NF-kappaB subunits in G1 and G2 phases, where Chk1 is inactive. However, in S-phase, Akt is inactivated, while Chk1 phosphorylates RelA and associates with IKKalpha, inhibiting the processing of the p100 (NF-kappaB2) subunit, which also plays a critical role in the regulation of these genes. These data reveal a complex regulatory network integrating NF-kappaB with the DNA-replication checkpoint and the expression of critical regulators of cell proliferation.

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