Loss of p53 enhances catalytic activity of IKKbeta through O-linked beta-N-acetyl glucosamine modification.
The IkappaB kinase (IKK)-NF-kappaB pathway plays a critical role in oncogenesis. Recently, we have shown that p53 regulates glucose metabolism through the IKK-NF-kappaB pathway and that, in the absence of p53, the positive feedback loop between IKK-NF-kappaB and glycolysis has an integral role in oncogene-induced cell transformation. Here, we demonstrate that IKKbeta, a component of the IKK complex, was constitutively modified with O-linked beta-N-acetyl glucosamine (O-GlcNAc) in both p53-deficient mouse embryonic fibroblasts (MEFs) and transformed human fibroblasts. In p53-deficient cells, the O-GlcNAcylated IKKbeta and the activating phosphorylation of IKK were decreased by p65/NF-kappaB knockdown or glucose depletion. We also found that high glucose induced the O-GlcNAcylation of IKKbeta and sustained the TNFalpha-dependent IKKbeta activity. Moreover, the O-GlcNAcase inhibitor streptozotocin intensified O-GlcNAcylation and concomitant activating phosphorylation of IKKbeta. Mutational analysis revealed that O-GlcNAcylation of IKKbeta occurred at Ser 733 in the C-terminal domain, which was identified as an inactivating phosphorylation site, suggesting that IKKbeta O-GlcNAcylation regulates its catalytic activity. Taken together, we propose a novel mechanism for the enhancement of NF-kappaB activity by loss of p53, which evokes positive feedback regulation from enhanced glucose metabolism to IKK in oncogenesis.
Kawauchi
Keiko
K
Department of Molecular Oncology, Institute of Gerontology, Nippon Medical School, Kawasaki, Kanagawa 211-8533, Japan.
Araki
Keigo
K
Tobiume
Kei
K
Tanaka
Nobuyuki
N
D000107:Acetylation / Q000187:drug effects; D000117:Acetylglucosamine / Q000378:metabolism*; D000818:Animals; D055162:Biocatalysis; D002460:Cell Line; D005947:Glucose / Q000494:pharmacology; D006019:Glycolysis; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*
D016159:Tumor Suppressor Protein p53; D051550:I-kappa B Kinase; D005947:Glucose; D000117:Acetylglucosamine