Impaired hair growth and wound healing in mice lacking thyroid hormone receptors

Area of Science:

• Endocrinology
• Dermatology
• Molecular Biology

Background:

• Thyroid status significantly impacts skin condition, affecting epidermis and hair growth.
• Hypothyroidism is linked to thin epidermis and common alopecia, suggesting thyroid hormones' role in skin proliferation and hair growth.

Purpose of the Study:

• To investigate the role of thyroid hormone receptors (TRs) in mediating thyroid hormone effects on skin.
• To elucidate the specific functions of TRα1 and TRβ in hair cycling, skin proliferation, and wound healing.

Main Methods:

• Utilized genetically modified mice lacking TRα1 and TRβ (TRα1/TRβ-deficient mice).
• Examined hair cycling, follicular and keratinocyte proliferation, and wound healing in these mice and in hypothyroid models.
• Assessed effects of individual TRα1 or TRβ deletion on hair cycling.

Main Results:

• TRα1/TRβ-deficient mice exhibited impaired hair cycling and reduced follicular hair cell proliferation, similar to hypothyroid mice.
• Individual deletion of TRα1 or TRβ did not affect hair cycling, suggesting a compensatory role.
• TRα1/TRβ-deficient mice developed alopecia after depilation and showed impaired wound healing with delayed re-epithelialization.

Conclusions:

• Thyroid hormone nuclear receptors (TRs) play a vital role in skin homeostasis, including hair growth and wound repair.
• The combined action of TRα1 and TRβ is essential for normal hair cycling and keratinocyte proliferation.
• TRs represent potential therapeutic targets for treating various skin pathologies.