Spanningsreactie op Adheren-knooppunten

Tissues like the skin and intestinal epithelium are constantly experiencing external mechanical forces such as pinching or stretching.

The adherens junctions that anchor these epithelial cells together can change dynamically in response to such mechanical tension. This conversion of mechanical stimuli into biochemical changes is called mechanotransduction.

In these cells, the adherens junctions form a continuous zone of attachment —the adhesion belt — comprising large clusters of cadherins, catenins, and actomyosin contractile bundles.

The alpha-catenins at these junctions act as mechanosensory proteins that change conformation in response to mechanical tension.

When increased contractile forces pull the actin filaments, the alpha-catenin changes from the folded to the unfolded conformation.

This unfolding opens a cryptic binding site to vinculin, a cytoskeletal binding protein that remains in its closed, inactive form in the cytoplasm.

Upon binding alpha-catenin, vinculin changes conformation to its open, active form.

The active vinculin promotes the recruitment of additional actin filaments to the site, thus strengthening the junction and distributing the force across the cells.