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Subtype specific roles of mitogen activated protein kinases in L6E9 skeletal muscle cell differentiation
Ashwani Khurana1, Chinmoy S Dey
1Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Punjab, India.
Abstract:
Role of mitogen activated protein kinases (MAPK) in skeletal muscle differentiation is not fully understood. We investigated subtype-specific functions and their interactions, if any, in the regulation of myogenic differentiation in L6E9 skeletal muscle cells. We show inhibition of extracellular signal-regulated kinase-1 and -2 (ERK-1/-2) and activation of p38 MAP kinase during the differentiation of L6E9 rat skeletal muscle cells under low serum condition. Inhibition of ERK-1/-2 activity dramatically enhanced differentiation as was evident from cellular morphology, expression of muscle differentiation specific marker proteins, suggesting that ERK-1/-2 activation may be inhibitory to initiation and progression of differentiation. In contrast, inhibition of p38 MAP kinase completely prevented differentiation; meaning p38 activation is required from the initiation till terminal differentiation of L6E9 cells. Moreover, inhibition of ERK-1/-2 activities enhanced the activation of p38 MAP kinase that resulted in enhancement of differentiation; whereas inhibition of p38 MAP kinase activity enhanced the ERK-1/-2 activities culminating in abrogation of differentiation. We conclude that ERK-1/-2 andp38 MAPkinase cascades oppositelyregulate each other's function(s) thereby regulating L6E9 skeletal muscle differentiation.
Insights
Mitogen-activated protein kinases (MAPK) play opposing roles in skeletal muscle differentiation. Extracellular signal-regulated kinase-1/-2 (ERK-1/-2) inhibits differentiation, while p38 MAPK activation is essential for it.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The precise roles of specific mitogen-activated protein kinase (MAPK) pathways in skeletal muscle differentiation remain incompletely elucidated.
- Understanding these pathways is crucial for insights into muscle development and regeneration.
Purpose of the Study:
- To investigate the subtype-specific functions and interactions of MAPKs in regulating myogenic differentiation.
- To elucidate the roles of extracellular signal-regulated kinase-1 and -2 (ERK-1/-2) and p38 MAPK in L6E9 skeletal muscle cell differentiation.
Main Methods:
- Utilized L6E9 rat skeletal muscle cells cultured under low serum conditions.
- Assessed cellular morphology and expression of muscle differentiation-specific marker proteins.
- Manipulated the activity of ERK-1/-2 and p38 MAP kinases using specific inhibitors.
Main Results:
- Inhibition of ERK-1/-2 activity significantly enhanced skeletal muscle cell differentiation.
- Activation of p38 MAPK was found to be essential for both the initiation and progression of differentiation.
- ERK-1/-2 and p38 MAPK cascades were shown to oppositely regulate each other's activity, influencing differentiation outcomes.
Conclusions:
- ERK-1/-2 signaling acts as an inhibitor of skeletal muscle differentiation in L6E9 cells.
- p38 MAPK signaling is indispensable for successful myogenesis.
- The antagonistic cross-talk between ERK-1/-2 and p38 MAPK pathways is a key regulatory mechanism governing skeletal muscle differentiation.