Recent publications from the Centre for Muscle Research
Read more to get an insight into some of our recent work
With a diverse portfolio across several muscle-related research areas, we have selected some of our recent publications to give you an insight into the cutting-edge work that we do here in the Centre for Muscle Research.
The Centre's research portfolio includes muscle development and growth, injury and repair, metabolism and disease, as well as tissue crosstalk between muscle and other organs within the body.
Of course, we can’t take all of the credit! The publications below showcase the collaborative research undertaken between the Centre and national/ international experts.
Metabolic remodelling of dystrophic skeletal muscle reveals biological roles for dystrophin and utrophin in adaptation and plasticity
Preferential damage to fast, glycolytic myofibres is common in many muscle-wasting diseases, including Duchenne muscular dystrophy (DMD). Promoting an oxidative phenotype could protect muscles from damage and ameliorate the dystrophic pathology with therapeutic relevance, but developing efficacious strategies requires an improved understanding of dystrophic muscle adaptation and plasticity. Our study combined whole transcriptome RNA sequencing and mitochondrial proteomics with assessments of metabolic and contractile function in two established mouse models of DMD during fast-to-slow muscle remodelling with chronic low-frequency electrical stimulation (LFS), which produces endurance-like muscle contractions. Our findings revealed novel biological roles of dystrophin and utrophin in the adaptation and plasticity of dystrophic muscle to chronic LFS, involving transcriptional reprogramming, remodelling of the mitochondrial proteome and respiratory chain supercomplexes, enhanced fibre respiration, and protection from contraction-induced injury. These findings, published in Molecular Metabolism, provided mechanistic bases for optimising efficacious LFS protocols for potential therapeutic application in DMD and related muscle disorders.
Lead author Dr. Justin Hardee is a McKenzie Research Fellow from The University of Melbourne. This work was a collaboration between the Centre for Muscle Research (The University of Melbourne), the Department of Anatomy and Physiology and the Department of Biochemistry and Molecular Biology (The University of Melbourne), Garvan Institute of Medical Research, UNSW, and McMaster University. This work was supported by research grants from the National Health and Medical Research Council and The University of Melbourne's School of Biomedical Sciences Early-Mid Career Research Association (EMCRA) Collaborative Award.
Dynamic Changes to the Skeletal Muscle Proteome and Ubiquitinome Induced by the E3 Ligase, ASB2β
Our study, published in the journal Molecular and Cellular Proteomics (MCP), was the first study to quantitatively examine changes to protein ubiquitination, and protein abundance, during muscle wasting that was triggered by an increase in the expression of an E3-ligase protein named ASB2β. E3 ligases play a crucial role in cells by tagging proteins with a molecule known as ubiquitin. Once a protein is tagged with one, or more, of these ubiquitin molecules, that protein’s function, location, activity and/or abundance may alter, leading to a change in cell size and function. In this study, we found that an increase in ASB2β protein leads to muscle wasting and impaired contractile function. This muscle wasting was associated with decreased mitochondrial and contractile protein abundance, and an increase in proteins involved in protein degradation (including other E3 ligases), protein synthesis and key structural proteins. As expected, an increase in ASB2β also altered the ubiquitination status of many different proteins. Importantly, our study showed, for the first time, the complexity of changes in the abundance of specific proteins during muscle wasting, and demonstrated that there is no simple relationship between changes in ubiquitination status of a protein and changes to its abundance in the cell. Overall, our study identified novel potential mechanisms by which ASB2β may negatively regulate muscle mass and function. By providing new insight into the complexity of these changes, our findings will hopefully support future discoveries into skeletal muscle and ubiquitin biology relevant to health and disease. For example, ASB2β is elevated in the pathological condition, type 1 myotonic dystrophy. Therefore, our findings may offer insight into pathological processes of relevance to this condition.
Read the paper here - https://pubmed.ncbi.nlm.nih.gov/33516941/
Lead author Dr. Craig Goodman is a Senior Research Fellow in the Centre for Muscle Research (The University of Melbourne). This work was supported by the National Health and Medical Research Council.
Iron accumulation in skeletal muscles of old mice is associated with impaired regeneration after ischaemia–reperfusion damage
Our study was the first to use Laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) to visualise iron accumulation in skeletal muscles of old and injured mice. Our comprehensive work demonstrated that oxidative stress is implicated in a range of chronic muscle wasting conditions. Very few studies have investigated the role of iron, which is elevated during ageing, in age‐related muscle wasting and blunted repair after injury and in our study, we showed that iron overload was exacerbated in old mice after ischemic reperfusion injury and was associated with increased lipid peroxidation and impaired muscle regeneration. Ischemic reperfusion injury is used to model injuries that occur during limb surgeries where the blood flow is temporarily occluded. Lower limb surgeries have a higher prevalence in the elderly population and can trigger complications and further hospitalisation. Understanding the response of aged muscle to ischemic reperfusion injury will provide insight into possible drug targets to attenuate complications. After identifying the iron overload in the aged and injured tissues, an iron chelator was used before or after ischemic reperfusion injury. However, reducing iron did not translate to structural improvements and increased the deposition of non-muscle tissue. Our results suggested that iron is involved in effective muscle regeneration, highlighting the importance of iron homeostasis in muscle atrophy and muscle repair.
Lead author Francesca Alves is a third year PhD student within the Centre for Muscle Research. This work was a collaboration between the Centre for Muscle Research (The University of Melbourne), the Department of Pharmacology and Therapeutics (The University of Melbourne) and the Melbourne Dementia Research Centre (The Florey Institute of Neuroscience and Mental Health, The University of Melbourne). This publication constituted the first stage of Francesca's PhD research.
Read the paper here - http://doi.org/10.1002/jcsm.12685
Bone Geometry Is Altered by Follistatin‐Induced Muscle Growth in Young Adult Male Mice
Our novel study investigated the crosstalk between two adjacent organs: muscle and bone. Published in the Journal of Bone and Mineral Research Plus (JBMR Plus), our study used cutting-edge molecular tools to interrogate whether larger, stronger muscles were able to promote stronger bones. To do this, we increased the size of muscles in mice (independent of exercise), and comprehensively analysed the adjacent bones through micro-computed tomography (micro-CT) and histological analyses. As a result, the findings from this study were the first to characterise the effect of large muscles on bone structure, in an adult mouse model. After 4-weeks of muscle hypertrophy, the diaphysis of the tibia was narrowed, and the site of muscle attachment (tibial crest) was significantly extended; both in order to accommodate for the growing muscle. Histological assessment further identified that this rapid change in bone structure was attributable to the paired activity of bone-forming and bone-resorbing cells, osteoblasts and osteoclasts, respectively. Their activity on opposing surfaces of the cortical bone allowed the ‘cortical drift’ of bone toward the central axis, resulting in a narrower shaft. These exciting findings are just the beginning of a series of studies headed by the teams at CMR and SVI, and as experts in both muscle and bone biology, we are determined to continue these studies to understand how muscles communicate to bone particularly in different contexts, such as during growth, disease, and ageing.
Lead author Dr. Audrey Chan is a Research Fellow in the Centre for Muscle Research. This work was the result of a collaboration between the Centre for Muscle Research (The University of Melbourne) and St Vincent’s Institute of Medical Research (SVI, Fitzroy).
Read the paper here: https://doi.org/10.1002/jbm4.10477
TMEPAI/PMEPA1 Is a Positive Regulator of Skeletal Muscle Mass
The Transforming Growth Factor Beta (TGF-β) superfamily of secreted molecules are well characterised as regulators of skeletal muscle size. We previously demonstrated the importance of blocking Myostatin and Activin, two members of the TGF-β signalling axis, to increase muscle mass in settings of muscular dystrophy and cancer associated muscle wasting. Current strategies to block TGF-β ligand activity have been met with mixed degrees of success in pre-clinical and clinical settings. Thus, alternate approaches to inhibit this pathway are required to better develop therapeutic interventions for muscle wasting conditions. Our team characterised the transmembrane associated protein, TMEPAI as a positive regulator of skeletal muscle mass. Using Adeno-associated viral vectors, we demonstrated that TMEPAI acts to block the intracellular actions of the TGF-β ligand Activin A to promote muscle mass in mice. Importantly, in the C26 colon carcinoma model of cancer cachexia where mice display progressive muscle wasting, TMEPAI expression was sufficient to reduce muscle atrophy. Our findings offer new insights into the regulation of muscle mass by the TGF-β superfamily and are the first to describe TMEPAI as a pro-growth factor.
Below, are images of skeletal muscle tissue sections highlighting the hypertrophic effects of AAV mediated expression of TMEPAI on individual muscle fibres of a mouse tibialis anterior muscle.
Read more here - https://www.frontiersin.org/articles/10.3389/fphys.2020.560225/full
Lead author Dr. Adam Hagg recently completed his PhD studies jointly supervised by A/Prof. Paul Gregorevic at the Centre for Muscle Research (The University of Melbourne) and A/Prof. Craig Harrison at the Biomedicine Discovery Institute (Monash University). This paper constituted a part of Adams PhD thesis and was a successfull and rewarding collaboration with the Growth Factor Therapeutics Laboratory group from Monash University.
Phosphorylation of ERK and dystrophin S3059 protect against inflammation-associated C2C12 myotube atrophy
One of the key protein complexes involved in the maintenance of normal skeletal muscle structure and size is the dystrophin-glycoprotein complex (DGC). The DGC is well characterised as a regulator of skeletal muscle force production, however more recently dystrophin and the DGC have been defined as an integral signalling complex at the sarcolemma. In a previous study, our team reported that the dystrophin protein isolated from healthy skeletal muscle is phosphorylated on multiple amino acids, and mutagenesis analyses revealed phosphorylation at the S3059 site enhances dystrophin interaction with β-dystroglycan. Therefore, mimicking phosphorylation of this site has the potential to reduce muscle wasting via increasing the stability of the DGC.
Our more recent study is the first to show that phosphorylation of a single amino acid within the dystrophin protein can reduce inflammation-associated muscle wasting in vitro. By overexpressing dystrophin plasmids containing either a phospho-null or phosphomimetic mutation at S3059 in mouse C2C12 myotubes in vitro, we identified that both phosphorylation of dystrophin S3059 and increased ERK activation enhanced the interaction between dystrophin and β-dystroglycan to provide protection against inflammation-induced skeletal muscle atrophy. Promoting stronger binding of dystrophin to β-dystroglycan has therapeutic potential for muscle wasting conditions associated with inflammation.
Read more here - American Journal of Physiology Cell Physiology
Lead author Dr. Kristy Swiderski is a Senior Research Fellow in the Centre for Muscle Research (The University of Melbourne). This work was supported by the National Health and Medical Research Council of Australia and The University of Melbourne Early Career Seed grant program.