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Regulation of C2C12 myogenic terminal differentiation by MKK3/p38alpha pathway
Candice Cabane1, Walter Englaro, Karen Yeow
1Unité Mixte de Recherche Centre National de la Recherche Scientifique 6548, Laboratoire de Physiologie Cellulaire et Moléculaire, Faculté des Sciences, Université de Nice-Sophia Antipolis, France.
Abstract:
The signal transduction pathways connecting cell surface receptors to the activation of muscle-specific promoters and leading to myogenesis are still largely unknown. Recently, a contribution of the p38 mitogen-activated protein kinase (MAPK) pathway to this process was evoked through the use of pharmacological inhibitors. We used several mutants of the kinases composing this pathway to modulate the activity of the muscle-specific myosin light chain and myogenin promoters in C2C12 cells by transient transfections. In addition, we show for the first time, using a stable C2C12 cell line expressing a dominant-negative form of the p38 activator MAPK kinase (MKK)3, that a functional p38 MAPK pathway is indeed required for terminal muscle cell differentiation. The most obvious phenotype of this cell line, besides the inhibition of the activation of p38, is its inability to undergo terminal differentiation. This phenotype is accompanied by a drastic inhibition of cell cycle and myogenesis markers such as p21, p27, MyoD, and troponin T, as well as a profound disorganization of the cytoskeleton.
Insights
The p38 mitogen-activated protein kinase (MAPK) pathway is crucial for muscle cell differentiation. Inhibiting this pathway prevents myogenesis and disrupts cell cycle markers and cytoskeleton organization.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Signal transduction pathways for myogenesis remain largely unknown.
- The p38 mitogen-activated protein kinase (MAPK) pathway's role in myogenesis was previously suggested using inhibitors.
Purpose of the Study:
- To investigate the role of the p38 MAPK pathway in muscle cell differentiation.
- To elucidate the molecular mechanisms connecting cell surface receptors to myogenesis.
Main Methods:
- Utilized C2C12 cells for transient transfections with kinase mutants.
- Created a stable C2C12 cell line expressing a dominant-negative MAPK kinase (MKK)3.
- Assessed muscle-specific promoter activity and expression of differentiation markers.
Main Results:
- A functional p38 MAPK pathway is essential for terminal muscle cell differentiation.
- Inhibition of the p38 pathway prevented differentiation and reduced cell cycle/myogenesis markers (p21, p27, MyoD, troponin T).
- Disorganization of the cytoskeleton was observed in cells with inhibited p38 MAPK activity.
Conclusions:
- The p38 MAPK pathway is a key regulator of terminal muscle cell differentiation.
- This pathway influences the expression of critical myogenesis and cell cycle regulatory proteins.
- Cytoskeletal integrity is linked to p38 MAPK-mediated myogenesis.