Abstract
BackgroundMuscle fibre hyperplasia stops in most fish when they reach approximately 50 % of their maximum body length. However, new small-diameter muscle fibres can be produced de novo in aged fish after muscle injury. Given that virtually nothing is known regarding the transcriptional mechanisms that regulate regenerative myogenesis in adult fish, we explored the temporal changes in gene expression during trout muscle regeneration following mechanical crushing. Then, we compared the gene transcription profiles of regenerating muscle with the previously reported gene expression signature associated with muscle fibre hyperplasia.ResultsUsing an Agilent-based microarray platform we conducted a time-course analysis of transcript expression in 29 month-old trout muscle before injury (time 0) and at the site of injury 1, 8, 16 and 30 days after lesions were made. We identified more than 7000 unique differentially expressed transcripts that segregated into four major clusters with distinct temporal profiles and functional categories. Functional categories related to response to wounding, response to oxidative stress, inflammatory processes and angiogenesis were inferred from the early up-regulated genes, while functions related to cell proliferation, extracellular matrix remodelling, muscle development and myofibrillogenesis were inferred from genes up-regulated 30 days post-lesion, when new small myofibres were visible at the site of injury. Remarkably, a large set of genes previously reported to be up-regulated in hyperplastic muscle growth areas was also found to be overexpressed at 30 days post-lesion, indicating that many features of the transcriptional program underlying muscle hyperplasia are reactivated when new myofibres are transiently produced during fish muscle regeneration.ConclusionThe results of the present study demonstrate a coordinated expression of functionally related genes during muscle regeneration in fish. Furthermore, this study generated a useful list of novel genes associated with muscle regeneration that will allow further investigations on the genes, pathways or biological processes involved in muscle growth and regeneration in vertebrates.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3160-x) contains supplementary material, which is available to authorized users.
Highlights
Muscle fibre hyperplasia stops in most fish when they reach approximately 50 % of their maximum body length
Using a DAVID analysis, we found that the most enriched functional categories inferred from genes common to the muscle hyperplasia signature and to cluster III
In our previous study on the genes up-regulated in trout hyperplastic growth area, we notably focused our work on genes that were potentially involved in myogenic cell differentiation and fusion, identifying many candidate genes encoding transcriptional regulators (DNA-binding regulators and epigenetic factors), immunoglobulin (Ig) domain-containing membrane receptors and secreted factors [9]
Summary
Muscle fibre hyperplasia stops in most fish when they reach approximately 50 % of their maximum body length. Using a myog:GFP transgenic line, we recently showed that small-diameter fluorescent myofibres can be produced de novo in wounded post-hyperplastic muscles of aged trout [5]. This neomyogenesis, which evokes muscle regeneration following injury in adult mammals [6, 7], indicates that the myotome of aged trout still contains myogenic cells that can be reactivated de novo when the microenvironment is permissive, such as after damages. We compared the gene transcription profiles of regenerating muscle with the molecular signatures associated with muscle hyperplasia which we previously defined using laser capture microdissection combined with the same Agilent-based microarray platform [9]
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