SASH1 interacts with TNKS2 and promotes human melanocyte stem cell maintenance

Area of Science:

• Genetics and Molecular Biology
• Dermatology
• Aging Research

Background:

• Aging is associated with opposing pigmentation changes: hyperpigmentation (age spots) and hypopigmentation (gray hair).
• The mechanistic link between these phenotypes and their underlying genetic basis remains unclear.
• This study investigates a family with an inherited pigmentation disorder to elucidate these mechanisms.

Approach:

• Clinical examination of family members identified a SASH1 S519N variant associated with premature graying and dyspigmentation.
• Cellular assays demonstrated that SASH1 promotes stem-like characteristics in human melanocytes.
• Protein interaction studies revealed SASH1 binds to tankyrase 2 (TNKS2), a crucial interaction for SASH1's function.

Key Points:

• The SASH1 S519N variant impairs SASH1's ability to promote melanocyte stem-like characteristics.
• The SASH1 S519N variant disrupts the binding interaction with tankyrase 2 (TNKS2).
• SASH1 is identified as a novel regulator of the balance between melanocyte stem cells and mature melanocytes.

Conclusions:

• SASH1 plays a critical role in maintaining melanocyte homeostasis.
• Defects in SASH1 function, particularly the S519N variant, lead to pigmentation abnormalities.
• Dysfunctional melanocyte stem cell maintenance is proposed as a unifying mechanism for aging-associated pigmentation disorders.