Background: Skeletal muscle fiber formation requires myoblast cell-cell membrane contact and fusion. Results: A versican-rich pericellular matrix surrounding myoblasts is proteolytically cleared by ADAMTS versicanases facilitating myoblast contact and fusion. Conclusion: Versican processing by ADAMTS versicanases contribute to muscle fiber formation. Significance: Targeting versican remodeling could enhance the regenerative capacity of muscle by improving muscle fiber fusion during regeneration.

Osteoarthritis (OA) is a highly prevalent joint disease. Its slow progressive nature and the correlation between pathological changes and clinical symptoms mean that OA is often well advanced by the time of diagnosis. In the absence of any specific pharmacological treatments, there is a pressing need to develop robust biomarkers for OA. We have adopted a nuclear magnetic resonance (NMR)-based metabolomic strategy to identify molecular responses to surgically induced OA in an animal model. Sheep underwent one of three types of surgical procedure (sham (control), meniscal destabilization, MD or anterior cruciate ligament transaction, ACLT), and for every animal a serum sample was collected both pre- and postoperatively, thus, affording two types of "control" data for comparison. 1D 1H NMR spectra were acquired from each sample at 800 MHz and the digitized spectral data were analyzed using principal components analysis and partial least-squares regression discriminant analysis. Our approach, combined with the study design, allowed us to separate the metabolic responses to surgical intervention from those associated with OA. We were able to identify dimethyl sulfone (DMSO2) as being increased in MD after 4 weeks, while ACLT-induced OA exhibited increased 3-methylhistidine and decreased branched chain amino acids (BCAAs). The findings are discussed in the context of interpretation of metabolomic results in studies of human disease, and the selection of appropriate "control" data sets.

Adipose tissue not only functions as a reserve to store energy but has become of major interest as an endocrine organ, releasing signalling molecules termed adipokines which impact on other tissues, such as skeletal muscle. Adipocytes, within skeletal muscle and adipose tissue, secrete adipokines to finely maintain the balance between feed intake and energy expenditure. This book chapter focuses on the three adipokines, adiponectin, leptin and IL-6, which have potent effects on skeletal muscle during rest and exercise. Similarly, adiponectin, leptin and IL-6 enhance glucose uptake and increase fatty acid oxidation in skeletal muscle. Fatty acid oxidation is increased through activation of AMPK (adenosine monophosphate-activated protein kinase signalling) causing phosphorylation and inhibition of ACC (acetyl-coenzyme A carboxylase), decreasing availability of malonyl CoA. Leptin and adiponectin also control feed intake via AMPK signalling in the hypothalamus. Adipokines function to maintain energy homeostasis, however, when feed intake exceeds energy expenditure adipokines can become dysregulated causing lipotoxicity in skeletal muscle and metabolic disease can prevail. Cross-talk between adipocytes and skeletal muscle via correct control by adipokines is important in controlling energy homeostasis during rest and exercise and can help prevent metabolic disease.