MITF Is Regulated by Redox Signals Controlled by the Selenoprotein Thioredoxin Reductase 1

Area of Science:

• Biochemistry
• Molecular Biology
• Dermatology

Background:

• Selenoproteins, including thioredoxin reductase 1 (TR1), exhibit complex roles in melanocytes and melanoma.
• While selenium supplementation can protect melanocytes and delay melanoma in mice, TR1 itself is linked to melanoma progression and metastasis in humans.

Purpose of the Study:

• To investigate the specific effects of TR1 reduction on melanocyte function and melanoma cells.
• To elucidate the molecular mechanisms by which TR1 influences pigmentation and tumorigenesis.

Main Methods:

• Utilized microRNA to reduce TR1 expression (TR1^low) in melanocytes.
• Employed CRISPR/Cas9 gene editing to disrupt the TR1 gene (TXNRD1) in melanoma cells.
• Assessed melanin content, tyrosinase (TYR) activity, TYR-related protein 1 (TYRP1) transcription, and microphthalmia-associated transcription factor (MITF) expression and modification.

Main Results:

• TR1^low melanocytes exhibited slower growth, reduced melanin content, lower TYR activity, and decreased TYRP1 transcription.
• TR1 gene disruption in melanoma cells led to the complete loss of the melanocyte-specific MITF isoform.
• Evidence suggests TR1 depletion causes oxidation of MITF, revealing a novel redox modification mechanism.

Conclusions:

• TR1 plays a critical role in regulating melanocyte differentiation and pigmentation through MITF.
• TR1 depletion-induced MITF oxidation represents a new pathway impacting both pigmentation and melanoma development.
• Targeting TR1 offers potential therapeutic strategies for managing pigmentation disorders and melanoma.