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m-Calpain implication in cell cycle during muscle precursor cell activation.
F Raynaud1, G Carnac, A Marcilhac
1UMR 5539-CNRS, Laboratoire de Motilité Cellulaire, EPHE, cc107, University of Montpellier 2 place Eugène Bataillon, 34090 France. raynaudf@univ-montp2.fr
Experimental Cell Research
|July 10, 2004
Summary
Milli-calpain controls muscle precursor cell activation and differentiation. This cysteine protease
Area of Science:
- Muscle regeneration
- Cellular biology
- Molecular mechanisms of muscle differentiation
Background:
- Milli-calpain (m-calpain) is a cysteine protease involved in skeletal muscle cell-cell fusion.
- Its role in the early stages of muscle precursor cell activation and differentiation is not well understood.
Purpose of the Study:
- To characterize the compartmentalization and activation of m-calpain during the initial steps of muscle precursor cell recruitment and differentiation.
- To investigate the role of m-calpain in cell cycle progression and gene expression during myogenesis.
Main Methods:
- Immunofluorescence analysis of m-calpain localization in proliferating and quiescent myoblasts and satellite cells.
- Inhibition of calpain activity using MDL 28170 to assess its impact on cell cycle progression and MyoD/Myf5 expression.
Main Results:
- M-calpain is localized in the nucleus of proliferating myoblasts but shifts to the cytoplasm upon quiescence.
- In satellite stem cells, m-calpain is absent in quiescent cells but appears in the nucleus upon proliferation after muscle injury.
- Calpain inhibition blocks cell cycle re-entry, prevents MyoD accumulation, and enhances Myf5 expression.
Conclusions:
- M-calpain plays a crucial role in controlling muscle precursor cell activation and cell cycle progression.
- These findings suggest a novel role for m-calpain in the early events of muscle regeneration.