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The metabolic and molecular mechanisms of hyperammonaemia and hyperethanolaemia induced protein catabolism in skeletal muscle cells

Crossland, Hannah; Smith, Kenneth; Atherton, Philip J.; Wilkinson, Daniel J.

Authors

Hannah Crossland mbzhc@exmail.nottingham.ac.uk

KENNETH SMITH KEN.SMITH@NOTTINGHAM.AC.UK
Professor of Metabolic Mass Spectrometry

PHILIP ATHERTON philip.atherton@nottingham.ac.uk
Professor of Clinical, metabolic & Molecular Physiology



Abstract

Hyperammonaemia and hyperethanolaemia are thought to be driving factors behind skeletal muscle myopathy in liver disease i.e. cirrhosis. Despite this, the singular and combined impacts of ethanol and ammonia induced protein catabolism are poorly defined. As such, we aimed to dissect out the effects of ammonia and ethanol on muscle catabolism. Murine C2C12 myotubes were treated with ammonium acetate (10 mM) and ethanol (100 mM) either alone or in combination for 4h and/or 24h. Myotube diameter, muscle protein synthesis and anabolic and catabolic signalling pathways were assessed. In separate experiments, cells were co-treated with selected inhibitors of protein breakdown to assess the importance of proteolytic pathways in protein loss with ammonia and ethanol. Ammonia and ethanol in combination resulted in a reduction in myotube width and total protein content, that was greater than the reduction observed with ammonia alone. Both ammonia and ethanol caused reductions in protein synthesis, as assessed by puromycin incorporation. There was also evidence of impairments in regulation of protein translation, and increased protein expression of markers of muscle protein breakdown. Myotube protein loss with ammonia plus ethanol was not affected by autophagy inhibition, but was completely prevented by proteasome inhibition. Thus, combined ammonia and ethanol incubation of C2C12 myotubes exacerbated myotube atrophy and dysregulation of anabolic and catabolic signalling pathways associated with either component individually. Ubiquitin proteasome-mediated protein breakdown appears to play an important role in myotube protein loss with ethanol and ammonia.

Citation

Crossland, H., Smith, K., Atherton, P. J., & Wilkinson, D. J. (2018). The metabolic and molecular mechanisms of hyperammonaemia and hyperethanolaemia induced protein catabolism in skeletal muscle cells. Journal of Cellular Physiology, 233(12), 9663-9673. https://doi.org/10.1002/jcp.26881

Journal Article Type Article
Acceptance Date May 23, 2018
Online Publication Date Aug 24, 2018
Publication Date 2018-12
Deposit Date Jun 7, 2018
Publicly Available Date Sep 5, 2018
Journal Journal of Cellular Physiology
Print ISSN 0021-9541
Electronic ISSN 1097-4652
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 233
Issue 12
Pages 9663-9673
DOI https://doi.org/10.1002/jcp.26881
Keywords Skeletal muscle; Protein catabolism; Hyper-ammonaemia
Public URL http://eprints.nottingham.ac.uk/id/eprint/52292
Publisher URL https://onlinelibrary.wiley.com/doi/abs/10.1002/jcp.26881
Copyright Statement Copyright information regarding this work can be found at the following address: http://eprints.nottingham.ac.uk/end_user_agreement.pdf

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