Proceedings of The Physiological Society

Mitochondria: Form and function (London, UK) (2017) Proc Physiol Soc 38, C04

Oral Communications

Assessing mitochondrial structure and function in C. elegans muscle

A. Pollard1, C. Gaffney2, J. Hewitt3, S. Vanapalli3, D. Constantin-Teodosiu4, P. Greenhaff4, T. Etheridge2, N. J. Szewczyk1

1. MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Nottingham, Derby, United Kingdom. 2. School of Sport & Health Sciences, University of Exeter, Exeter, United Kingdom. 3. Department of Chemical Engineering, Texas Tech University, Lubbock, Texas, United States. 4. MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Nottingham, Nottingham, United Kingdom.

Caenorhabditis elegans is a small laboratory animal commonly used for genomics studies. It has also been used for landmark studies of development, signal transduction, gene silencing, and ageing as well as clinically relevant studies of mitochondrial disease. We have been using this worm to study genes and signals that regulate muscle homeostasis. In our studies of "muscle genes", kinases, and phosphatases that appear to be required for muscle homeostasis, we discovered that mitochondrial structure, as assessed by GFP labelled mitochondria, was much more frequently disrupted than sarcomere structure; NB. these observations represents knockdown of roughly 10% of the total genome. Therefore, we have been using a number of techniques to assess mitochondrial structure and function in C. elegans muscle. As with many systems, MitoTracker dyes can be used to assess mitochondrial structure and function in all tissues, both in vivo and via fluorescence-activated cell sorting (FACS) based separation. Using FACS, we find that muscle mitochondria comprise roughly 20% of all mitochondria in C. elegans. We have used similar dyes such as JC-1 to show progressive loss of mitochondrial membrane potential in vivo in response to genetically locking open a degenerin cation channel, UNC-105, in muscle. In muscular dystrophy mutants we have employed the Seahorse instrument to demonstrate alterations in oxygen consumption. We have also combined these techniques and others, such as citrate synthase activity and maximal rates of ATP synthesis, to study processes of physiologic interest. For example, we find that mitochondrial structure is an early event in ageing muscle and this is preceded by decreases in mitochondrial function. Lastly, we have begun to use these techniques to assess the impact of compounds that may improve mitochondrial structure and function. For example, ongoing studies suggest that GYY4137 improves mitochondrial structure with age and mitochondrial function in muscular dystrophy. By having applied a variety of techniques, we feel that we are now able to get a comprehensive view of mitochondrial structural and functional capacity in C. elegans and use this worm in basic, applied, and translational mitochondrial research.

Where applicable, experiments conform with Society ethical requirements