Reviewer #3 (Public Review): A Novel Imaging Method (FIM-ID) Reveals that Myofibrillogenesis Plays a Major Role in the Mechanically Induced Growth of Skeletal Muscle
Year: 2024
Type: peer-review
Abstract: An increase in mechanical loading, such as that which occurs during resistance exercise, induces radial growth of muscle fibers (i.e., an increase in cross-sectional area).Muscle fibers are largely composed of myofibrils, but whether radial growth is mediated by an increase in the size of the myofibrils (i.e., myofibril hypertrophy) and/or the number of myofibrils (i.e., myofibrillogenesis) is not known.Electron microscopy (EM) can provide images with the level of resolution that is needed to address this question, but the acquisition and subsequent analysis of EM images is a time-and cost-intensive process.To overcome this, we developed a novel method for visualizing myofibrils with a standard fluorescence microscope (FIM-ID).Images from FIM-ID have a high degree of resolution and contrast, and these properties enabled us to develop pipelines for automated measurements of myofibril size and number.After extensively validating the automated measurements, we used both mouse and human models of increased mechanical loading to discover that the radial growth of muscle fibers is largely mediated by myofibrillogenesis.Collectively, the outcomes of this study offer insight into a fundamentally important topic in the field of muscle growth and provide future investigators with a time-and cost-effective means to study it. eLife assessmentThe work by Hornberger and team presents a novel workflow for the visualisation of myofibrils with high resolution and contrast that will be highly valued by the scientific community.The methods include solid validation of both sample preparation and analysis, and have been used to make the fundamental discovery of myofibrillogenesis as the mechanism of mechanical loading-induced growth.Whether this mechanism is present in other settings of muscle growth (i.e., nonloading), other striated tissue (e.g myocardium), or is sex-dependent, will require future experiments.
Source: eLife
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $2,500
OpenAlex ID: W4391787038