Skeletal muscle O-GlcNAc transferase is important for muscle energy homeostasis and whole-body insulin sensitivity

Hao Shi, Alexander Munk, Thomas Svava Nielsen, Morgan R Daughtry, Louise Larsson, Shize Li, Kasper F Høyer, Hannah W Geisler, Karolina Sulek, Rasmus Kjøbsted, Taylor Fisher, Marianne M. Andersen, Zhengxing Shen, Ulrik K Hansen, Eric M England, Zhiyong Cheng, Kurt Højlund, Jørgen Wojtaszewski, Xiaoyong Yang, Matthew W HulverRichard F Helm, Jonas Thue Treebak, David E Gerrard

27 Citationer (Scopus)
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Abstract

OBJECTIVE: Given that cellular O-GlcNAcylation levels are thought to be real-time measures of cellular nutrient status and dysregulated O-GlcNAc signaling is associated with insulin resistance, we evaluated the role of O-GlcNAc transferase (OGT), the enzyme that mediates O-GlcNAcylation, in skeletal muscle.

METHODS: We assessed O-GlcNAcylation levels in skeletal muscle from obese, type 2 diabetic people, and we characterized muscle-specific OGT knockout (mKO) mice in metabolic cages and measured energy expenditure and substrate utilization pattern using indirect calorimetry. Whole body insulin sensitivity was assessed using the hyperinsulinemic euglycemic clamp technique and tissue-specific glucose uptake was subsequently evaluated. Tissues were used for histology, qPCR, Western blot, co-immunoprecipitation, and chromatin immunoprecipitation analyses.

RESULTS: We found elevated levels of O-GlcNAc-modified proteins in obese, type 2 diabetic people compared with well-matched obese and lean controls. Muscle-specific OGT knockout mice were lean, and whole body energy expenditure and insulin sensitivity were increased in these mice, consistent with enhanced glucose uptake and elevated glycolytic enzyme activities in skeletal muscle. Moreover, enhanced glucose uptake was also observed in white adipose tissue that was browner than that of WT mice. Interestingly, mKO mice had elevated mRNA levels of Il15 in skeletal muscle and increased circulating IL-15 levels. We found that OGT in muscle mediates transcriptional repression of Il15 by O-GlcNAcylating Enhancer of Zeste Homolog 2 (EZH2).

CONCLUSIONS: Elevated muscle O-GlcNAc levels paralleled insulin resistance and type 2 diabetes in humans. Moreover, OGT-mediated signaling is necessary for proper skeletal muscle metabolism and whole-body energy homeostasis, and our data highlight O-GlcNAcylation as a potential target for ameliorating metabolic disorders.

OriginalsprogEngelsk
TidsskriftMolecular Metabolism
Vol/bind11
Sider (fra-til)160-177
Antal sider18
ISSN2212-8778
DOI
StatusUdgivet - maj 2018

Emneord

  • Det Natur- og Biovidenskabelige Fakultet

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