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Regulation of cyclins and p34CDC2 expression during terminal differentiation of C2C12 myocytes

J Wang1, B Nadal-Ginard

  • 1Department of Cardiology, Children's Hospital, Boston, Massachusetts 02115.

Biochemical and Biophysical Research Communications
|January 5, 1995
PubMed

Insights

Skeletal muscle cells permanently exit the cell cycle upon differentiation. This study shows that downregulation of cyclins and cyclin-dependent kinases prevents cell cycle reentry in these differentiated cells.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Muscle Development

Background:

  • Terminal differentiation of skeletal muscle cells involves permanent cell cycle withdrawal.
  • The precise molecular mechanisms underlying this cell cycle arrest are not fully understood.

Purpose of the Study:

  • To investigate the expression patterns of key cell cycle regulatory genes during skeletal muscle cell differentiation.
  • To determine if differentiated myotubes can re-enter the cell cycle and the role of specific genes in this process.

Main Methods:

  • Utilized C2C12 myoblast cell line for differentiation studies.
  • Analyzed the expression of cyclin A, cyclin D1, and p34cdc2 during myogenesis.
  • Investigated the effect of SV40 large T antigen on cell cycle reentry in differentiated myotubes.

Main Results:

  • Cyclin A, cyclin D1, and p34cdc2 expression decreased significantly upon C2C12 myocyte differentiation.
  • These genes were not inducible in terminally differentiated myotubes.
  • SV40 large T antigen induced cell cycle entry in myotubes by upregulating these genes and affecting pRB phosphorylation and Rb expression.

Conclusions:

  • Irreversible downregulation of cyclins and cyclin-dependent kinases is a key mechanism for permanent cell cycle withdrawal in skeletal muscle cells.
  • This study provides direct evidence for the role of cell cycle regulators in maintaining the differentiated state of myotubes.

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