Epithelial-Mesenchymal

The mammalian gastric mucosa and its glands are formed by simple cylindrical mucus secreting epithelium, and gastric tubular glands reaching the muscular layer, underneath; the structure of these glands differs according to the gastric anatomical area [cardias, body, pylori] . Epithelial cells are attached to each other at their lateral membranes by a complex of intercellular junctions that maintain the cells together. The most apical of them is the occluding junction also known as zonula occludens, or tight junction. This complex is composed of multiple proteins that include transmembrane proteins, cytoplasmic signaling proteins, and adapters that link them to the actin cytoskeleton. The transmembrane proteins mediate the major functions of the tight junction: barrier, pore, and fence. Claudins are barrier-forming proteins. They regulate paracellular permeability, can form pores, especially small pores, or enhance water permeability. They are considered the major determinants of the permeability properties of epithelial cells. There are 27 claudins in mammals grouped in eight subgroups; they are expressed in a tissue-specific pattern and distributed in all the cell-cell contact areas in epithelia. There is abundant evidence on the function and tissue specificity of claudins. Multiple claudin isoforms are expressed simultaneously at the tight junction.

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Last date updated on September, 2024