Adhäsionskontakte

Adhäsionskontakte, also known as adhesion junctions, are specialized structures that facilitate and maintain cell-to-cell and cell-to-extracellular matrix (ECM) contacts. They play a crucial role in various biological processes, including tissue development, morphogenesis, and tissue homeostasis. Adhäsionskontakte are dynamic structures that can be categorized into three main types based on their composition and function: tight junctions, gap junctions, and adherens junctions.

Tight junctions are critical for forming impermeable barriers between cells, regulating the passage of molecules and ions between cells. They consist of transmembrane proteins, such as occludin, claudins, and junctional adhesion molecules (JAMs), which form a continuous belt around the apical membrane of adjacent cells.

Gap junctions, on the other hand, allow for the direct exchange of small molecules, such as ions, second messengers, and nutrients, between the cytoplasm of adjacent cells. These junctions are formed by connexons, which are clusters of six transmembrane proteins called connexins.

Adherens junctions are responsible for linking the actin cytoskeleton of adjacent cells to the ECM and to each other. They consist of transmembrane proteins, such as E-cadherin, which bind to the cytoplasmic proteins, α-catenin and β-catenin, forming a link to the actin cytoskeleton.

Adhäsionskontakte are essential for many physiological processes, including wound healing, immune response, and organ development. They are also implicated in various pathological conditions, such as cancer, where they can promote cell invasion, metastasis, and resistance to therapy. Understanding the molecular mechanisms underlying adhesion junction formation and regulation is therefore crucial for developing new therapeutic strategies.