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p38 MAPK-induced nuclear factor-kappaB activity is required for skeletal muscle differentiation: role of

Bernat Baeza-Raja1, Pura Muñoz-Cánoves

  • 1Center for Genomic Regulation, Program on Differentiation and Cancer, E-08003 Barcelona, Spain.

Molecular Biology of the Cell
|February 10, 2004
PubMed

Insights

p38 MAPK and nuclear factor-kappaB (NF-kappaB) signaling pathways are crucial for skeletal muscle development. This study reveals NF-kappaB as a downstream effector of p38, highlighting their crosstalk and the role of IL-6 in myogenesis.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • p38 MAPK and NF-kappaB signaling pathways influence skeletal myogenesis.
  • The precise role of NF-kappaB in myoblast differentiation is debated.
  • p38 MAPK is a known promoter of myoblast differentiation.

Purpose of the Study:

  • To investigate the interplay between p38 MAPK and NF-kappaB during skeletal myogenesis.
  • To elucidate the downstream effectors of this signaling crosstalk.
  • To determine the role of Interleukin-6 (IL-6) in the context of p38 and NF-kappaB signaling in myogenesis.

Main Methods:

  • Utilized C2C12 myoblast cell line.
  • Analyzed p38 and NF-kappaB activation during proliferation and differentiation.
  • Assessed NF-kappaB activity in response to p38 activation.
  • Measured IkappaBalpha levels and NF-kappaB-DNA binding.
  • Quantified p65-NF-kappaB transactivating potential.
  • Investigated IL-6 expression and its impact on myogenesis via mRNA interference and overexpression.

Main Results:

  • p38 MAPK activation is specific to differentiating myocytes, while NF-kappaB is active throughout.
  • NF-kappaB activation is dependent on p38 activity during differentiation, with NF-kappaB acting as a p38 effector.
  • p38 activation enhances NF-kappaB activity by reducing IkappaBalpha and increasing p65-NF-kappaB transactivation.
  • IL-6 expression is upregulated in a p38- and NF-kappaB-dependent manner during myoblast differentiation.
  • Modulating IL-6 levels directly impacts myogenic differentiation extent, and IL-6 can rescue NF-kappaB inhibition effects.

Conclusions:

  • Established a novel crosstalk mechanism between p38 MAPK and NF-kappaB signaling in skeletal myogenesis.
  • Identified NF-kappaB as a downstream effector of p38 MAPK during myoblast differentiation.
  • Demonstrated that IL-6 is a key promyogenic effector downstream of the p38-NF-kappaB pathway.

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