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FoxO3a preferentially induces p27Kip1 expression while impairing muscle precursor cell-cycle progression
Christopher R Rathbone1, Frank W Booth, Simon J Lees
1Department of Biomedical Sciences, University of Missouri-Columbia, Columbia, Missouri 65211, USA. rathbone@email.arizona.edu
Muscle & Nerve
|September 27, 2007
Summary
The forkhead transcription factor FoxO3a hinders muscle precursor cell (MPC) proliferation by increasing the inhibitor p27Kip1. Attenuating FoxO3a may improve skeletal muscle regeneration and prevent atrophy.
Area of Science:
- Molecular Biology
- Cell Biology
- Muscle Physiology
Background:
- Forkhead transcription factors, including FoxO subfamily, are crucial in muscle atrophy.
- Muscle precursor cell (MPC) proliferation is vital for maintaining skeletal muscle mass.
Purpose of the Study:
- To investigate the hypothesis that FoxO3a inhibits MPC proliferation.
- To determine the effects of FoxO3a overexpression on in vitro MPC proliferation.
Main Methods:
- Overexpression of wild-type FoxO3a in MPCs using adenovirus.
- Assessing DNA synthesis via 5-bromo-2' deoxyuridine incorporation.
- Analyzing promoter activity and protein levels of cell cycle regulators (p27Kip1, p21Waf/Cip1, retinoblastoma protein, cyclin D1).
Main Results:
- FoxO3a overexpression decreased DNA synthesis in MPCs.
- Increased promoter activity and protein levels of p27Kip1 were observed.
- No significant effect or a decrease in p21Waf/Cip1 was noted.
- FoxO3a did not affect early G1-S phase transition markers.
Conclusions:
- FoxO3a acts as a negative regulator of MPC proliferation.
- FoxO3a's role extends beyond inducing muscle atrophy to inhibiting MPC proliferation.
- Reducing elevated FoxO3a levels could potentially restore MPC proliferation, combat atrophy, and enhance muscle regeneration.
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