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The small heat shock protein alphaB-crystallin inhibits differentiation-induced caspase 3 activation and myogenic

Ryuji Ikeda1, Kenichi Yoshida, Mina Ushiyama

  • 1Department of Clinical Pharmacy and Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Sakuragaoka, Kagoshima, Japan. ikeda@m.kufm.kagoshima-u.ac.jp

Biological & Pharmaceutical Bulletin
|September 2, 2006
PubMed

Insights

Small heat shock protein alphaB-crystallin suppresses apoptosis and differentiation in C2C12 myoblasts. Overexpression of alphaB-crystallin reduces MyoD and myogenin, impacting myogenic differentiation and cell death pathways.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Muscle Development

Background:

  • Myoblasts differentiate into myotubes or undergo apoptosis upon growth factor deprivation.
  • Apoptosis and differentiation in myogenic lineages may share common cellular pathways.
  • Small heat shock proteins, like alphaB-crystallin, are involved in cellular stress responses.

Purpose of the Study:

  • To investigate the role of alphaB-crystallin in C2C12 myoblast differentiation and apoptosis.
  • To determine the effect of alphaB-crystallin overexpression on myogenic regulatory factors (MyoD, myogenin) and caspase 3 activity.

Main Methods:

  • C2C12 myoblasts were cultured and induced to differentiate.
  • Adenovirus vectors expressing alphaB-crystallin were used to overexpress the protein.
  • Expression levels of alphaB-crystallin, MyoD, and myogenin were analyzed.
  • Caspase 3 activity was measured to assess apoptosis.

Main Results:

  • AlphaB-crystallin, MyoD, and myogenin expression increased early during C2C12 myogenic differentiation.
  • Overexpression of alphaB-crystallin suppressed differentiation-induced apoptosis.
  • AlphaB-crystallin overexpression inhibited caspase 3 activation.
  • Suppression of differentiation and decreased MyoD/myogenin expression were observed with alphaB-crystallin overexpression.

Conclusions:

  • Stress, such as growth factor deprivation, is critical for apoptosis during myogenic differentiation.
  • AlphaB-crystallin acts as a suppressor of myogenic differentiation, apoptosis, and caspase 3 activity in C2C12 cells.
  • AlphaB-crystallin may modulate overlapping mechanisms involved in differentiation and apoptosis in the myogenic lineage.

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