Notch pathway signaling in the skin antagonizes Merkel cell development

Area of Science:

• Developmental biology
• Cell biology
• Dermatology

Background:

• Merkel cells are essential mechanosensitive cells in the epidermis, crucial for touch sensation.
• Their development relies on the transcription factor Atoh1, but regulatory pathways remain unclear.
• The Notch pathway is known to antagonize Atoh1 in various developmental contexts.

Purpose of the Study:

• To investigate the role of Notch signaling in regulating Merkel cell development and patterning.
• To determine if Notch pathway activation inhibits Merkel cell production.

Main Methods:

• Utilized conditional genetic manipulation in mouse epidermis to alter Notch signaling.
• Overexpressed the Notch intracellular domain (NICD) to constitutively activate Notch signaling.
• Deleted the RBPj gene, an essential binding partner for NICD, to inhibit Notch signaling.
• Examined the effects on Merkel cell numbers, distribution, and the expression of downstream targets like Hes1.

Main Results:

• Constitutive NICD overexpression in mouse epidermis reduced Merkel cell numbers in whisker follicles and touch domes.
• Conditional deletion of RBPj increased Merkel cell numbers, induced ectopic Merkel cells, and altered their distribution.
• Deletion of Hes1, a Notch effector, also led to increased Merkel cell numbers in whisker follicles.

Conclusions:

• Notch signaling plays a critical role in negatively regulating Merkel cell production.
• The Notch pathway influences the patterning and quantity of Merkel cells in the skin.
• These findings elucidate a key regulatory mechanism governing Merkel cell development.