Thyroid hormones and skeletal muscle--new insights and potential implications

Area of Science:

• Endocrinology
• Muscle Physiology
• Molecular Biology

Background:

• Thyroid hormone signalling is vital for energy, development, and growth, with skeletal muscle as a key target.
• Skeletal muscle expresses type 2 and 3 iodothyronine deiodinases (DIO2 and DIO3), which regulate active tri-iodothyronine (T3) levels.
• Deiodinases control intracellular T3 availability, a critical pre-receptor mechanism for myogenesis and muscle homeostasis.

Purpose of the Study:

• To review the role of T3 in skeletal muscle development and homeostasis.
• To focus on the deiodinase-mediated control of local T3 signalling in muscle.
• To explore therapeutic applications of deiodinase activity in muscle repair.

Main Methods:

• Literature review of thyroid hormone signalling in skeletal muscle.
• Analysis of the roles of DIO2 and DIO3 in T3 regulation within myocytes.
• Discussion of deiodinase function in muscle homeostasis, pathology, and therapeutic strategies.

Main Results:

• DIO2 generates active T3, while DIO3 inactivates it, providing localized T3 control.
• Local deiodinase activity is crucial for regulating T3 signalling during myogenesis.
• Deiodinase-mediated T3 control impacts muscle homeostasis and response to injury.

Conclusions:

• Local deiodinase activity represents a critical cell-autonomous mechanism for modulating T3 signalling in skeletal muscle.
• Understanding deiodinase function offers potential therapeutic targets for muscle disorders, atrophy, and injury.
• Targeting skeletal muscle deiodinase activity could enhance satellite-cell-mediated muscle regeneration.