Tumor necrosis factor alpha regulates myogenesis to inhibit differentiation and promote proliferation in satellite...

Area of Science:

• Muscle biology
• Cellular signaling
• Skeletal muscle regeneration

Background:

• Tumor necrosis factor-alpha (TNF-α) and NF-κB signaling are implicated in skeletal muscle wasting across various conditions, including cancer cachexia.
• These pathways influence muscle-specific ubiquitin ligase expression, leading to muscle degradation.
• Existing research suggests TNF-α and NF-κB signaling suppresses muscle differentiation by downregulating MyoD protein levels, yet is also crucial for myoblast proliferation.

Purpose of the Study:

• To elucidate the complex role of TNF-α and NF-κB signaling in myogenesis and skeletal muscle regeneration.
• To investigate the specific effects of TNF-α on skeletal muscle fiber width and myoblast differentiation.
• To examine the in vivo impact of TNF-α and NF-κB signaling on satellite cell behavior during muscle regeneration.

Main Methods:

• Organ culture model to assess TNF-α effects on single skeletal muscle fibers.
• In vitro experiments to analyze TNF-α and p65's impact on MyoD transactivation and myoblast differentiation.
• In vivo studies to evaluate TNF-α's effect on satellite cell number and NF-κB signaling during muscle regeneration.

Main Results:

• TNF-α was observed to reduce the width of single skeletal muscle fibers in organ culture.
• TNF-α and p65 were found to repress MyoD transactivation, thereby suppressing myoblast differentiation.
• TNF-α treatment increased satellite cell number, and NF-κB signaling activation was detected during the proliferation stage of in vivo skeletal muscle regeneration.

Conclusions:

• TNF-α and NF-κB signaling play a dual role in myogenesis, inhibiting differentiation while promoting satellite cell proliferation.
• These findings clarify the intricate regulation of skeletal muscle regeneration by TNF-α and NF-κB pathways.
• Understanding this balance is crucial for developing therapeutic strategies targeting muscle wasting and promoting repair.