The genetics of vertebrate myogenesis

Key Points

  • Vertebrate myogenesis is a complex process that has been studied in a range of model systems.

  • Myogenic regulatory factors and paired box (Pax) genes are involved in the cell-autonomous regulation of myogenesis. The context of myogenesis is determined by the nature of signals secreted from surrounding tissues, which have an important role in myogenic induction. Myogenesis can be separated into three phases — primary myotome formation, muscle growth and adult myogenesis.

  • Cell movements and cell adhesion have important roles in the early myotome.

  • Satellite cells seem to be responsible for regulating the majority of the processes involved in adult myogenesis.

Abstract

The molecular, genetic and cellular bases for skeletal muscle growth and regeneration have been recently documented in a number of vertebrate species. These studies highlight the role of transient subcompartments of the early somite as a source of distinct waves of myogenic precursors. Individual myogenic progenitor populations undergo a complex series of cell rearrangements and specification events in different regions of the body, all of which are controlled by distinct gene regulatory networks. Collectively, these studies have opened a window into the morphogenetic and molecular bases of the different phases of vertebrate myogenesis, from embryo to adult.

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Figure 1: Signalling pathways for myogenic induction and integrity.
Figure 2: Primary and secondary myogenesis in the chick (a,b,c) and zebrafish (d,e,f).
Figure 3: Somite-cell movements in Xenopus laevis and zebrafish.
Figure 4: Adult myogenesis.

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Acknowledgements

We are most grateful to S. Dietrich for her extensive comments on the manuscript and the communication of unpublished data. We would also like to thank R. P. Currie for comments on the manuscript.

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Glossary

Primary myotome

The first differentiated muscle to derive from the dermomyotome.

Satellite cell

Resident stem cell of adult skeletal muscle.

Somite

A metameric division of the vertebrate mesoderm, which gives rise to a number of lineage-restricted cellular compartments, including the dermomyotome.

Paraxial mesoderm

Mesodermal tissue that lies lateral to the notochord and that segments to form the somites.

Dermomyotome

Epithelial layer derived from dorsal division of the amniote somite. It generates a number of different cell types, including the muscles and dermis of the back.

Epaxial

Epaxial muscles generate the muscles of the back in amniotes and are defined by their innervation by the dorsal branch of the spinal nerve.

Hypaxial

Hypaxial muscles derive from the ventro–lateral portion of the dermomyotome. They are innervated by ventral spinal nerves and give rise to body-wall muscles and, at limb level, the appendicular muscle as well as a number of migratory muscle populations such as the diaphragm and hypoglossal chord or tongue.

Lateral plate mesoderm

Mesoderm that is found at the periphery of the embryo, lateral to the paraxial mesoderm.

Fast- and slow-twitch muscle

Fast- and slow-twitch muscles are distinguished by their rate of contraction, which is imparted by the expression of specific myosin isoforms.

Sclerotome

Ventrally located somitic subcompartment that contributes the progenitors of the axial skeleton.

Hyperplasia

The division and proliferation of progenitor cells to increases cell number.

Hypertrophy

Growth produced by an increase in the size of individual cells without an increase in cell number.

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Bryson-Richardson, R., Currie, P. The genetics of vertebrate myogenesis. Nat Rev Genet 9, 632–646 (2008). https://doi.org/10.1038/nrg2369

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