Cited by 231Circadian rhythm and melatoninMetabolism, Diabetes, and CancerAdipose Tissue and Metabolism

Muscle-specific loss of Bmal1 leads to disrupted tissue glucose metabolism and systemic glucose homeostasis

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Harfmann, Brianna D., Schroder, Elizabeth A., Kachman, Maureen T., Hodge, Brian A., Zhang, Xiping, Esser, Karyn A.·2016·Skeletal Muscle

Abstract

BACKGROUND: Diabetes is the seventh leading cause of death in the USA, and disruption of circadian rhythms is gaining recognition as a contributing factor to disease prevalence. This disease is characterized by hyperglycemia and glucose intolerance and symptoms caused by failure to produce and/or respond to insulin. The skeletal muscle is a key insulin-sensitive metabolic tissue, taking up ~80 % of postprandial glucose. To address the role of the skeletal muscle molecular clock to insulin sensitivity and glucose tolerance, we generated an inducible skeletal muscle-specific Bmal1 (-/-) mouse (iMSBmal1 (-/-)). RESULTS: Progressive changes in body composition (decreases in percent fat) were seen in the iMSBmal1 (-/-) mice from 3 to 12 weeks post-treatment as well as glucose intolerance and non-fasting hyperglycemia. Ex vivo analysis of glucose uptake revealed that the extensor digitorum longus (EDL) muscles did not respond to either insulin or 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) stimulation. RT-PCR and Western blot analyses demonstrated a significant decrease in mRNA expression and protein content of the muscle glucose transporter (Glut4). We also found that both mRNA expression and activity of two key rate-limiting enzymes of glycolysis, hexokinase 2 (Hk2) and phosphofructokinase 1 (Pfk1), were significantly reduced in the iMSBmal1 (-/-) muscle. Lastly, results from metabolomics analyses provided evidence of decreased glycolytic flux and uncovered decreases in some tricarboxylic acid (TCA) intermediates with increases in amino acid levels in the iMSBmal1 (-/-) muscle. These findings suggest that the muscle is relying predominantly on fat as a fuel with increased protein breakdown to support the TCA cycle. CONCLUSIONS: These data support a fundamental role for Bmal1, the endogenous circadian clock, in glucose metabolism in the skeletal muscle. Our findings have implicated altered molecular clock dictating significant changes in altered substrate metabolism in the absence of feeding or activity changes. The changes in body composition in our model also highlight the important role that changes in skeletal muscle carbohydrate, and fat metabolism can play in systemic metabolism.

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Authors
Harfmann, B. D., Schroder, E. A., Kachman, M. T., Hodge, B. A., Zhang, X., & Esser, K. A.
Affiliations
  • University of Kentucky (US)
  • University of Michigan (US)
Corresponding author
Esser, Karyn A.
Venue
Skeletal Muscle
Published
2016-03-30
Volume
6
Issue
1
Pages
12-12
ISSN
2044-5040 (ISSN-L)
OpenAlex
W2333878333
Cited by
231
References
38
Citations by year
2026: 24 · 2025: 30 · 2024: 24 · 2023: 20 · 2022: 29 · 2021: 19 · 2020: 33 · 2019: 17 · 2018: 15 · 2017: 18 · 2016: 2
FWCI
11.03
Type
journal article
Language
en
Open access
Locations
  • Skeletal Muscle (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • University of Florida Digital Collections (University of Florida) (submittedVersion, other-oa)
  • UKnowledge (University of Kentucky) (submittedVersion, cc-by)
Funders
National Institutes of Health (R01AR066082, RC1ES018636)
Topics
  • Life Sciences › Neuroscience › Endocrine and Autonomic Systems › Circadian rhythm and melatonin
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Metabolism, Diabetes, and Cancer
  • Health Sciences › Medicine › Physiology › Adipose Tissue and Metabolism
Keywords
Bmal1, circadian clock, glucose metabolism, glucose homeostasis, impaired glucose tolerance, hyperglycemia, insulin sensitivity, GLUT4, hexokinase 2, phosphofructokinase-1, glycolysis, TCA cycle, substrate metabolism, fat metabolism, protein degradation, body composition, diabetes mellitus
MeSH terms
Adipose Tissue, Aminoimidazole Carboxamide, Animals, Blood Glucose, Body Weight, Circadian Rhythm, Female, Hexokinase, Homeostasis, Hypoglycemic Agents, Insulin, Male, Motor Activity, Ribonucleotides, RNA, Messenger, Mice, Knockout, Muscle, Skeletal, Phosphofructokinase-1, Muscle Type, Glucose Transporter Type 4, Mice, ARNTL Transcription Factors

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