title: Age- and Activity-Related Differences in the Abundance of Myosin Essential and Regulatory Light Chains in Human Muscle.
abstract: Traditional methods for phenotyping skeletal muscle (e.g., immunohistochemistry) are labor-intensive and ill-suited to multixplex analysis,i.e., assays must be performed in a series. Addressing these concerns represents a largely unmet research need but more comprehensive parallel analysis of myofibrillar proteins could advance knowledge regarding age- and activity-dependent changes in human muscle. We report a label-free, semi-automated and time efficient LC-MS proteomic workflow for phenotyping the myofibrillar proteome. Application of this workflow in old and young as well as trained and untrained human skeletal muscle yielded several novel observations that were subsequently verified by multiple reaction monitoring (MRM). We report novel data demonstrating that human ageing is associated with lesser myosin light chain 1 content and greater myosin light chain 3 content, consistent with an age-related reduction in type II muscle fibers. We also disambiguate conflicting data regarding myosin regulatory light chain, revealing that age-related changes in this protein more closely reflect physical activity status than ageingper se. This finding reinforces the need to control for physical activity levels when investigating the natural process of ageing. Taken together, our data confirm and extend knowledge regarding age- and activity-related phenotypes. In addition, the MRM transitions described here provide a methodological platform that can be fine-tuned to suite multiple research needs and thus advance myofibrillar phenotyping.
authors.affiliation: Division of Sport and Exercise Science, Abertay University, 40 Bell Street, Kydd Building, Dundee DD1 1HG, UK. j.cobley@abertay.ac.uk.
authors.forename: James N
authors.initials: JN
authors.lastname: Cobley
authors.affiliation: Faculty of Sport Science and Coaching, Universiti Pendidikan Sultan Idris, Tanjung Malim, Perak 35900, Malaysia. zulezwan@fsskj.upsi.edu.my.
authors.forename: Zulezwan
authors.initials: Z
authors.lastname: Ab Malik
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK. j.p.morton@ljmu.ac.uk.
authors.forename: James P
authors.initials: JP
authors.lastname: Morton
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK. g.l.close@ljmu.ac.uk.
authors.forename: Graeme L
authors.initials: GL
authors.lastname: Close
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK. b.j.edwards@ljmu.ac.uk.
authors.forename: Ben J
authors.initials: BJ
authors.lastname: Edwards
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK. j.burniston@ljmu.ac.uk.
authors.forename: Jatin G
authors.initials: JG
authors.lastname: Burniston
keywords: ageing; human skeletal muscle; myosin heavy chain; myosin light chain; selective reaction monitoring