Sci. STKE, 19 September 2000
Immune Signals A Tale of NFB: Act1, Seen CIKS
Nuclear factor B is an important transcription factor that regulates immune responses and skin epithelial development. The proteins that activate latent cytoplasmic NF-B exist in a huge complex of approximately 900 kD. Two new reports have identified and characterized a new protein (termed Act1 or CIKS) that promotes the activation of NF-B. Li et al. identified Act1 as a 60-kD protein lacking any obvious catalytic domains, but predicted to contain a helix-loop-helix domain. Constitutive expression of Act1 led to the activation of NF-B and JNK, in the absence of cellular stimulation. Whereas Li et al. observed that expression of a dominant negative (DN) form of the NF-B interacting kinase, NIK, could block Act-1-dependent activation of an NF-B-dependent reporter gene, Leonardi et al. observed a less severe effect mediated by DN-NIK on Act1. Act1 immunoprecipitated with IB kinase (IKK) (also called NEMO) and activated the IKK complex, and Act1 was bound to IKKα and IKKβ but not to NIK (Leonardi et al.), suggesting that Act1 might be influenced by NIK, but in an indirect manner. The helix-loop-helix in the NH2-terminal of Act1 was necessary for NF-B activation and association with the IKK complex.
Li, X., Commane, M., Nie, H., Hua, X., Chatterjee-Kishore, M., Wald, D., Haag, M., and Stark, G.R. (2000) Act1, an NF-B-activating protein. Proc. Natl. Acad. Sci. U.S.A. 97: 10489-10493. [Abstract] [Full Text]
Leonardi, A., Chariot, A., Claudio, E., Cunningham, K., and Siebenlist, U. (2000) CIKS, a connection to IB kinase and stress-activated protein kinase. Proc. Natl. Acad. Sci. U.S.A. 97: 10494-10499. [Abstract] [Full Text]
Citation: A Tale of NFB: Act1, Seen CIKS. Sci. STKE 2000, tw5 (2000).
Science Signaling. ISSN 1937-9145 (online), 1945-0877 (print). Pre-2008: Science's STKE. ISSN 1525-8882