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Updated: Aug 13, 2026
Cryosectioning of Contiguous Regions of a Single Mouse Skeletal Muscle for Gene Expression and Histological Analyses
Published on: December 12, 2016
Expression of MRF4 protein in adult and in regenerating muscles in Xenopus
Christel Becker1, Bruno Della Gaspera, Michèle Guyot
1Biologie du Développement et de la Différenciation Musculaire, LNRS UMR 7060 CNRS, Université René Descartes, Paris, France.
Abstract:
In Xenopus, previous studies showed that the transcripts of the myogenic regulatory factor (MRF) MRF4 accumulate during skeletal muscle differentiation, but nothing is known about the accumulation of XMRF4 protein during myogenesis. In this report, an affinity-purified polyclonal antibody against Xenopus MRF4 was developed and used to describe the pattern of expression of this myogenic factor in the adult and in regenerating muscles. From young forming myotubes, XMRF4 protein persistently accumulated in nuclei during the regeneration process and was strongly expressed in nuclei of adult muscles. No selective accumulation of XMRF4 protein was detectable at neuromuscular junctions, but XMRF4 immunoreactivity was observed in sole plate nuclei as well as in extrasynaptic myofiber nuclei. We also report that XMRF4 protein accumulated before the establishment of neuromuscular connections, showing that innervation is not necessary for the appearance of XMRF4 protein during muscle regeneration.
Insights
Xenopus MRF4 protein accumulates in muscle nuclei during regeneration and in adult muscles. Its appearance during regeneration does not require innervation, indicating it is an early event in muscle repair.
Area of Science:
- Developmental Biology
- Muscle Regeneration
- Xenopus laevis Research
Background:
- Previous studies indicated MRF4 transcript accumulation during Xenopus skeletal muscle differentiation.
- The protein expression pattern of Xenopus MRF4 (XMRF4) during myogenesis remained uncharacterized.
Purpose of the Study:
- To characterize the protein expression pattern of XMRF4 during muscle regeneration and in adult Xenopus muscles.
- To determine if innervation is required for XMRF4 protein accumulation during muscle regeneration.
Main Methods:
- Development of an affinity-purified polyclonal antibody against Xenopus MRF4.
- Immunohistochemical analysis of XMRF4 protein expression in adult and regenerating Xenopus muscles.
Main Results:
- XMRF4 protein persistently accumulated in nuclei of regenerating myotubes and was strongly expressed in adult muscle nuclei.
- XMRF4 immunoreactivity was observed in sole plate and extrasynaptic myofiber nuclei, but not selectively at neuromuscular junctions.
- XMRF4 protein accumulation occurred prior to neuromuscular connection establishment during regeneration.
Conclusions:
- XMRF4 protein expression is a feature of both adult and regenerating Xenopus muscles.
- Innervation is not a prerequisite for XMRF4 protein appearance during muscle regeneration, suggesting its role in early regenerative processes.
