Cancer Cell
Volume 30, Issue 2, 8 August 2016, Pages 290-307
Journal home page for Cancer Cell

Article
Regulation of OGT by URI in Response to Glucose Confers c-MYC-Dependent Survival Mechanisms

https://doi.org/10.1016/j.ccell.2016.06.023Get rights and content
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Highlights

  • URI/OGT/PP1γ forms a functional heterotrimeric complex in cancer cells

  • Glucose depletion phosphorylates URI at Ser-371, releasing PP1γ to inhibit OGT

  • OGT inhibition reduces c-MYC, promoting cancer cell survival upon metabolic stress

  • URI (S371A) increases O-GlcNAcylation, c-MYC levels, and hepatocarcinogenesis

Summary

Cancer cells can adapt and survive under low nutrient conditions, but underlying mechanisms remain poorly explored. We demonstrate here that glucose maintains a functional complex between the co-chaperone URI, PP1γ, and OGT, the enzyme catalyzing O-GlcNAcylation. Glucose deprivation induces the activation of PKA, which phosphorylates URI at Ser-371, resulting in PP1γ release and URI-mediated OGT inhibition. Low OGT activity reduces O-GlcNAcylation and promotes c-MYC degradation to maintain cell survival. In the presence of glucose, PP1γ-bound URI increases OGT and c-MYC levels. Accordingly, mice expressing non-phosphorylatable URI (S371A) in hepatocytes exhibit high OGT activity and c-MYC stabilization, accelerating liver tumorigenesis in agreement with c-MYC oncogenic functions. Our work uncovers that URI-regulated OGT confers c-MYC-dependent survival functions in response to glucose fluctuations.

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