Somatostatin regulates tight junction function and composition in human keratinocytes.

Area of Science:

• Dermatology
• Endocrinology
• Cell Biology

Background:

• The role of the somatostatin (SST) and its receptors (SSTR1-5) system in skin biology remains largely unexplored.
• SST is a regulatory peptide hormone with known functions in various physiological processes.
• The epidermis expresses all five SSTR subtypes, suggesting potential roles in skin homeostasis.

Purpose of the Study:

• To investigate the presence and function of the SST/SSTR system in human skin.
• To elucidate the specific role of somatostatin receptor subtype 3 (SSTR3) and its interaction with MUPP1 in keratinocytes.
• To determine if SST influences the barrier function of epidermal tight junctions (TJs).

Main Methods:

• Detection of SST expression in human skin.
• Co-localization studies of SSTR3 and MUPP1 in primary cultured human keratinocytes.
• Assessment of TJ permeability under varying calcium conditions and SST treatment.
• Analysis of TJ protein expression (e.g., claudin-4) following long-term SST exposure.

Main Results:

• SST is expressed in human skin, including keratinocytes, Merkel cells, and dendritic cells.
• SSTR3 and MUPP1, a tight junction protein, interact in keratinocytes.
• SST treatment regulates TJ permeability and affects the expression of TJ proteins like claudin-4 in cultured keratinocytes.
• This study provides the first evidence of a peptide hormone modulating TJ function and composition in human keratinocytes.

Conclusions:

• The somatostatin/somatostatin receptor system, particularly SSTR3/MUPP1, plays a significant role in regulating skin barrier function.
• SST can modulate the permeability and protein composition of epidermal tight junctions.
• These findings suggest that peptide hormones offer a novel mechanism for controlling skin barrier characteristics.