Elevation of global O-GlcNAc levels in 3T3-L1 adipocytes by selective inhibition of O-GlcNAcase does not induce insulin resistance

• Author(s) / Creator(s)

  • Bubb, Abigail K.
  • Macauley, Matthew S.
  • Davies, Gideon J.
  • Vocadlo, David J.
  • Martinez-Fleites, Carlos

• The O-GlcNAc post-translational modification is considered to act as a sensor of nutrient flux through the hexosamine biosynthetic pathway. A cornerstone of this hypothesis is that global elevation of protein O-GlcNAc levels, typically induced with the non-selective O-GlcNAcase inhibitor PUGNAc (O-(2-acetamido-2-deoxy-d-glycopyranosylidene) amino-N-phenylcarbamate), causes insulin resistance in adipocytes. Here we address the potential link between elevated O-GlcNAc and insulin resistance by using a potent and selective inhibitor of O-GlcNAcase (NButGT (1,2-dideoxy-2′-propyl-α-d-glucopyranoso-[2,1-d]-Δ2′-thiazoline), 1200-fold selectivity). A comparison of the structures of a bacterial homologue of O-GlcNAcase in complex with PUGNAc or NButGT reveals that these inhibitors bind to the same region of the active site, underscoring the competitive nature of their inhibition of O-GlcNAcase and the molecular basis of selectivity. Treating 3T3-L1 adipocytes with NButGT induces rapid increases in global O-GlcNAc levels, but strikingly, NButGT treatment does not replicate the insulin desensitizing effects of the non-selective O-GlcNAcase inhibitor PUGNAc. Consistent with these observations, NButGT also does not recapitulate the impaired insulin-mediated phosphorylation of Akt that is induced by treatment with PUGNAc. Collectively, these results suggest that increases in global levels of O-GlcNAc-modified proteins of cultured adipocytes do not, on their own, cause insulin resistance.

• Date created

  2008

• Subjects / Keywords

  • Structural Insights
  • In-Vivo
  • Mechanisms
  • Nag-Thiazoline
  • Proteins
  • Beta-N-Acetylglucosamine
  • Skeletal-Muscle
  • Substrate-Assisted Catalysis
  • Glycosylation
  • Sequence-Based Classification

• Type of Item

  Article (Published)

• DOI

  https://doi.org/10.7939/R3Z60CG89

• License

  © 2008 Matthew S. Macauley et al. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.