Until now, it was known that muscle regenerates through a complex process that involves several steps and is dependent on stem cells.
Now, a new study describes a mechanism of muscle regeneration after physiological damage, which is based on the rearrangement of muscle fiber nuclei and is independent of muscle stem cells: The finding will serve to better understand muscle repair in both physiological and disease contexts. .
The team discovered an alternative muscle tissue repair mechanism that is autonomous from muscle fibers
The work, published in the magazine Science, was led by researchers from the Pompeu Fabra University (UPF), the National Center for Cardiovascular Research (CNIC), Center for Biomedical Research Network on Neurodegenerative Diseases (CYBERNED and the João Lobo Antunes Institute of Molecular Medicine (iMM, Portugal).
the fabric of skeletal muscleOrgan responsible for locomotion, it is formed by cells – fibers – that have multiple nuclei, an almost unique feature in our body. Despite its plasticity, its contraction may be accompanied by muscle damage.
as explained William Roman, first author of the study, “even under physiological conditions, regeneration is vital for muscles that support the mechanical stress of contraction, which often causes cell damage“
“Although muscle repair has been deeply investigated over the past few decades,” says Roman, “most studies have focused on mechanisms involving various types of cells, including muscle stem cells, which are needed in the event of muscle injury. Extensive”.
However, it adds Pura Muñoz-Cánoves, who is leading this work, have now discovered “an alternative muscle tissue repair mechanism that is autonomous from muscle fibers.”
Nuclear movement to damage sites
The team used different models in vitro injury and exercise models in rats and humans note that, when injured, the fiber nuclei are attracted to the injury site, which accelerates the repair of contractile units. Next, the researchers analyzed the molecular mechanism of that observation.
“Our experiments with muscle cells in the laboratory demonstrated that the movement of nuclei to the sites of injury caused the local release of messenger RNA molecules (MRNA). These mRNA molecules are translated into proteins at the injury site and act as building blocks for muscle repair,” says Roman.
“This process of self-repair of muscle fibers it occurs rapidly in rats and humans after exercise-induced muscle injury and, therefore, represents an energy- and time-efficient protective mechanism for the repair of small injuries”, adds Muñoz-Cánoves.
In addition to its implications for muscle research, this study also presents more general concepts for muscle cell biology, as nuclear movement towards injury sites.
The movement of nuclei caused the local delivery of mRNA molecules that, at the site of injury, are translated into muscle repair proteins
William Roman, UPF researcher and first author of the study
For Edgar R. Gomes, group leader at iMM and co-director of the study, “One of the most fascinating things about these cells is the movement during development of their nuclei, the largest organelles within the cell, but the reasons they move are largely unknown” .
Now, “we have shown a functional relevance for this phenomenon in adulthood during cell repair and regeneration”, stresses the Portuguese researcher.
“This discovery constitutes an important advance in the understanding of muscle biology, physiology – including that of exercise – and muscle dysfunction,” the authors conclude.
Reference:
Roman et al. “Muscle repair after physiological damage depends on nuclear migration for cell reconstruction.” Science 2021
Rights: Creative Commons.
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