Skeletal Muscles Do Not Undergo Apoptosis During Either Atrophy or Programmed Cell Death-Revisiting the Myonuclear...

Area of Science:

• Muscle biology
• Cellular biology
• Skeletal muscle physiology

Background:

• Skeletal muscles are large, multinucleated cells crucial for movement.
• The myonuclear domain hypothesis posits that nuclei number changes with muscle size (hypertrophy/atrophy).
• Hypertrophy is linked to new nuclei addition, but myonuclei fate during atrophy is debated.

Purpose of the Study:

• To investigate the fate of myonuclei during skeletal muscle atrophy.
• To challenge the prevailing interpretation of the myonuclear domain hypothesis regarding nuclei loss.

Main Methods:

• Utilized two independent models: one in rodents and another in insects.
• Employed experimental designs to differentiate true myonuclei from surrounding cells.
• Observed skeletal muscle fibers undergoing atrophy and programmed cell death.

Main Results:

• Demonstrated that nuclei are not lost from skeletal muscle fibers during atrophy.
• Evidence suggests nuclei also persist during programmed cell death in muscle fibers.
• Contradicted findings reporting significant myonuclei loss via apoptosis during atrophy.

Conclusions:

• The number of myonuclei does not decrease during skeletal muscle atrophy.
• Once acquired, myonuclei are permanent fixtures of skeletal muscle fibers.
• The myonuclear domain hypothesis requires re-evaluation based on persistent myonuclei.