Calcium-switch technique and junctional permeability in native rabbit esophageal epithelium

Area of Science:

• Epithelial Biology
• Cellular Physiology
• Biochemistry

Background:

• The esophageal epithelium forms a barrier regulating paracellular permeability.
• Understanding the molecular mechanisms governing epithelial barrier function is essential for gastrointestinal health.

Purpose of the Study:

• To investigate the role of calcium (Ca2+) in regulating paracellular permeability across rabbit esophageal epithelium.
• To elucidate the molecular components and mechanisms underlying calcium-dependent junctional resealing.

Main Methods:

• Utilized the Ca(2+)-switch technique in Ussing chambers to measure transepithelial electrical resistance (R(T)) in rabbit esophageal epithelium.
• Manipulated extracellular and intracellular Ca(2+) levels and assessed junctional resealing.
• Investigated the involvement of E-cadherin using antibodies and synthetic peptides.
• Performed immunohistochemistry to localize E-cadherin.

Main Results:

• Transepithelial electrical resistance (R(T)) significantly decreased in Ca(2+)-free conditions and reversed upon Ca(2+) restoration, demonstrating a Ca(2+)-dependent barrier.
• Junctional resealing was specific to Ca(2+), dose-dependent, and independent of intracellular Ca(2+) or protein synthesis.
• Luminal antibodies targeting E-cadherin inhibited resealing, and E-cadherin localization was altered by Ca(2+) availability.

Conclusions:

• Esophageal epithelial junctions possess a significant Ca(2+)-dependent component critical for barrier function.
• This Ca(2+)-dependent adhesion is mediated by the extracellular domain of E-cadherin, involving a specific recognition sequence.