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Loss of p53 enhances catalytic activity of IKKbeta through O-linked beta-N-acetyl glucosamine modification.

ABSTRACT: 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.

SUBMITTER: Kawauchi K

PROVIDER: S-EPMC2651314 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature

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Loss of p53 enhances catalytic activity of IKKbeta through O-linked beta-N-acetyl glucosamine modification.

Kawauchi Keiko K Araki Keigo K Tobiume Kei K Tanaka Nobuyuki N

Proceedings of the National Academy of Sciences of the United States of America 20090206 9

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-defici ...[more]

PMID: 19202066

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Project description:A gene cluster involved in N-glycan metabolism was identified in the genome of Bacteroides thetaiotaomicron VPI-5482. This gene cluster encodes a major facilitator superfamily transporter, a starch utilization system-like transporter consisting of a TonB-dependent oligosaccharide transporter and an outer membrane lipoprotein, four glycoside hydrolases (α-mannosidase, β-N-acetylhexosaminidase, exo-α-sialidase, and endo-β-N-acetylglucosaminidase), and a phosphorylase (BT1033) with unknown function. It was demonstrated that BT1033 catalyzed the reversible phosphorolysis of β-1,4-D-mannosyl-N-acetyl-D-glucosamine in a typical sequential Bi Bi mechanism. These results indicate that BT1033 plays a crucial role as a key enzyme in the N-glycan catabolism where β-1,4-D-mannosyl-N-acetyl-D-glucosamine is liberated from N-glycans by sequential glycoside hydrolase-catalyzed reactions, transported into the cell, and intracellularly converted into α-D-mannose 1-phosphate and N-acetyl-D-glucosamine. In addition, intestinal anaerobic bacteria such as Bacteroides fragilis, Bacteroides helcogenes, Bacteroides salanitronis, Bacteroides vulgatus, Prevotella denticola, Prevotella dentalis, Prevotella melaninogenica, Parabacteroides distasonis, and Alistipes finegoldii were also suggested to possess the similar metabolic pathway for N-glycans. A notable feature of the new metabolic pathway for N-glycans is the more efficient use of ATP-stored energy, in comparison with the conventional pathway where β-mannosidase and ATP-dependent hexokinase participate, because it is possible to directly phosphorylate the D-mannose residue of β-1,4-D-mannosyl-N-acetyl-D-glucosamine to enter glycolysis. This is the first report of a metabolic pathway for N-glycans that includes a phosphorylase. We propose 4-O-β-D-mannopyranosyl-N-acetyl-D-glucosamine:phosphate α-D-mannosyltransferase as the systematic name and β-1,4-D-mannosyl-N-acetyl-D-glucosamine phosphorylase as the short name for BT1033.

Dataset Information

Loss of p53 enhances catalytic activity of IKKbeta through O-linked beta-N-acetyl glucosamine modification.

Publications

Loss of p53 enhances catalytic activity of IKKbeta through O-linked beta-N-acetyl glucosamine modification.

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