Permeability barrier dysfunction in transgenic mice overexpressing claudin 6

Area of Science:

• Dermatology and developmental biology
• Epithelial barrier function research
• Neonatal health and disease modeling

Background:

• Defective epidermal permeability barrier (EPB) is a critical factor in premature birth complications and neonatal mortality.
• Mechanisms underlying EPB formation and maintenance are not fully elucidated.
• Claudins, a family of tight junction proteins, are potential contributors to EPB integrity.

Purpose of the Study:

• To investigate the role of claudin 6 (Cldn6) in epidermal differentiation and EPB formation.
• To engineer a mouse model for studying EPB defects relevant to premature birth.

Main Methods:

• Generation of transgenic mice overexpressing claudin 6 (Cldn6) under the control of the involucrin (Inv) promoter.
• Assessment of EPB integrity through water loss measurements and X-gal penetration assays.
• Biochemical analysis of epidermal differentiation markers and claudin expression profiles.

Main Results:

• Transgenic mice (Inv-Cldn6) exhibited a defective EPB, leading to increased water loss and X-gal penetration, resulting in death within 2 days of birth.
• Aberrant expression of late epidermal differentiation markers (K1, filaggrin, loricrin, etc.) and altered epidermal claudin profiles were observed.
• Downregulation of repetin and SPRR1A/2A, linked to Klf4 downregulation, suggests impaired protein crossbridging and defective cornified envelopes.

Conclusions:

• Claudin 6 plays a crucial role in epithelial differentiation and the formation of a functional epidermal permeability barrier.
• The Inv-Cldn6 transgenic mouse model mimics human premature EPB defects, offering a valuable tool for studying related morbidities.
• Findings provide novel insights into the molecular mechanisms governing epidermal barrier development and the consequences of its disruption.