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Rap1A protein interferes with various MAP kinase activating pathways in skeletal myogenic cells

V Pizon1, G Baldacci

  • 1Institut André Lwoff, UPR 1983, Villejuif, France.

Oncogene
|January 9, 2001
PubMed

Insights

Rap1A protein regulates muscle cell differentiation by influencing mitogen-activated protein kinase (MAPK) pathways. Activated Rap1A inhibits differentiation, while inactivated Rap1A promotes it, impacting ERK signaling.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Signal Transduction

Background:

  • Rap1A protein's role in MAPK activation is known in various cell types.
  • Its specific signaling pathways in myogenic cells remain underexplored.
  • Rap1A influences myogenic C2 cell differentiation and endocytic compartments.

Purpose of the Study:

  • To investigate MAP kinase (MAPK) activity in C2 myoblasts.
  • To analyze signaling pathways activated by Rap1A in myogenic cells.
  • To understand Rap1A's impact on ERK activation and differentiation.

Main Methods:

  • Utilized control C2 myoblasts and stable C2 cell lines expressing mutated Rap1A proteins.
  • Investigated mitogen-activated protein (MAP) kinase activity.
  • Analyzed ERK activation pathways, including Raf/MEK and PI3K pathways.

Main Results:

  • Rap1A mutants promote ERK activation; active Rap1A induces more sustained activation than inactive Rap1A.
  • Transient ERK activation in control and inactivated Rap1A cells involves Raf/MEK-dependent, PI3K/Raf-independent, and undetermined pathways.
  • A PI3K/Raf/MEK-dependent pathway mediates transient ERK activation in cells expressing activated Rap1A.
  • Rap1A's interference with ERK activation depends on myoblast state and MAPK stimulation duration.

Conclusions:

  • Rap1A plays a complex role in regulating ERK activation in myogenic cells.
  • The state of myoblasts and MAPK stimulation duration influence Rap1A's effect on ERK activation.
  • Understanding these pathways is crucial for comprehending muscle cell differentiation.

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