Calcified Tissue International

, Volume 103, Issue 2, pp 198–205 | Cite as

Uncarboxylated Osteocalcin Enhances Glucose Uptake Ex Vivo in Insulin-Stimulated Mouse Oxidative But Not Glycolytic Muscle

  • Xuzhu Lin
  • Lewan Parker
  • Emma Mclennan
  • Xinmei Zhang
  • Alan Hayes
  • Glenn McConell
  • Tara C. Brennan-Speranza
  • Itamar LevingerEmail author
Original Research


Uncarboxylated osteocalcin (ucOC) stimulates muscle glucose uptake in mice EDL and soleus muscles. However, whether ucOC also exerts a similar effect in insulin-stimulated muscles in a muscle type-specific manner is currently unclear. We aimed to test the hypothesis that, with insulin stimulation, ucOC per se has a greater effect on oxidative muscle compared with glycolytic muscle, and to explore the underlying mechanisms. Mouse (C57BL6, male 9–12 weeks) extensor digitorum longus (EDL) and soleus muscles were isolated and longitudinally split into halves. Muscle samples were treated with varying doses of recombinant ucOC (0, 0.3, 1, 3, 30 ng/ml), followed by insulin addition. Muscle glucose uptake, protein phosphorylation and total expression of protein kinase B (Akt), Akt substrate of 160 kDa (AS160), extracellular signal-regulated kinase isoform 2 (ERK2), and adenosine monophosphate-activated protein kinase subunit α (AMPKα) were assessed. ucOC treatment at 30 ng/ml enhanced muscle glucose uptake in insulin-stimulated soleus, a mainly oxidative muscle (17.5%, p < 0.05), but not in EDL—a mostly glycolytic muscle. In insulin-stimulated soleus only, ucOC treatment (3 and 30 ng/ml) increased phosphorylation of AS160 and ERK2, but not Akt or AMPKα. The ucOC-induced increase in ERK2 phosphorylation in soleus was not associated with the increase in glucose uptake or AS160 phosphorylation. ucOC enhances glucose uptake and AS160 phosphorylation in insulin-stimulated oxidative but not glycolytic muscle, via upstream mechanisms which appear to be independent of ERK or AMPK.


Uncarboxylated osteocalcin Insulin stimulation Skeletal muscle type Glucose uptake AS160 ERK 



Associate Professor Itamar Levinger is a Future Leader Fellow supported by Australian Heart Foundation (ID: 100040).

Author Contributions

XL, XZ, TS, and IL designed the study; XL, LP, and EM performed experiments; XL and LP analyzed the data; XL, LP, AH, GM, TS, and IL interpreted the results; XL wrote the first draft of the paper; XL, LP, XZ, AH, GM, TS, and IL edited and revised the manuscript; All authors approved final version of the manuscript.

Compliance with Ethical Standards

Conflict of interest

Xuzhu Lin, Lewan Parker, Emma Mclennan, Xinmei Zhang, Alan Hayes, Glenn McConell, Tara C. Brennan-Speranza, and Itamar Levinger declare no conflict of interest.

Human and Animal Rights and Informed Consent

All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  • Xuzhu Lin
    • 1
  • Lewan Parker
    • 1
    • 2
  • Emma Mclennan
    • 1
  • Xinmei Zhang
    • 1
    • 3
  • Alan Hayes
    • 1
    • 4
    • 5
  • Glenn McConell
    • 1
  • Tara C. Brennan-Speranza
    • 6
  • Itamar Levinger
    • 1
    • 3
    Email author
  1. 1.Institute of Health and Sport (IHES)Victoria UniversityMelbourneAustralia
  2. 2.Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition SciencesDeakin UniversityMelbourneAustralia
  3. 3.School of Health and Biomedical SciencesRMIT UniversityMelbourneAustralia
  4. 4.College of Health and BiomedicineVictoria UniversityMelbourneAustralia
  5. 5.Australian Institute for Musculoskeletal ScienceVictoria UniversityMelbourneAustralia
  6. 6.Department of Physiology and Bosch Institute for Medical ResearchUniversity of SydneySydneyAustralia

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