Desmosome

Desmosome

Diagram of a desmosome

A desmosome is a specialized structure within the cell membrane that functions as a cell junction to provide strong adhesion between cells. Desmosomes are crucial for maintaining the structural integrity of tissues that experience mechanical stress, such as the epidermis, myocardium, and certain epithelial tissues.

Structure

Desmosomes are composed of several key components:

• Desmogleins and desmocollins: These are transmembrane cadherin proteins that extend into the intercellular space and mediate adhesion between adjacent cells.
• Plakoglobin and plakophilins: These are intracellular proteins that link the cadherins to the intermediate filament network within the cell.
• Desmoplakin: This protein binds to the intermediate filaments, anchoring the desmosome to the cytoskeleton.

The combination of these proteins forms a dense plaque on the cytoplasmic side of the cell membrane, which is connected to the intermediate filaments, providing mechanical strength.

Function

Desmosomes play a critical role in:

• Cell adhesion: They provide strong adhesive connections between cells, preventing them from being pulled apart under stress.
• Tissue integrity: By linking the intermediate filaments of adjacent cells, desmosomes help distribute mechanical forces across a tissue, maintaining its structural integrity.
• Signal transduction: Desmosomes are involved in signaling pathways that regulate cell proliferation, differentiation, and apoptosis.

Clinical Significance

Defects in desmosomal proteins can lead to a variety of diseases, known as desmosomal disorders. These include:

• Pemphigus vulgaris: An autoimmune disease where antibodies target desmogleins, leading to blistering of the skin and mucous membranes.
• Arrhythmogenic right ventricular cardiomyopathy (ARVC): A genetic disorder affecting the heart muscle, often linked to mutations in desmosomal proteins.
• Epidermolysis bullosa simplex: A condition characterized by fragile skin that blisters easily, sometimes associated with defects in desmosomal components.

Related pages

• Cell junction
• Cadherin
• Intermediate filament
• Epidermis
• Myocardium