Desmosomes are specialized structures that serve as strong adhesive junctions between cells. Found in animal tissues, they act like “spot welds” or “rivets” to hold adjacent cells together. These cellular connections are fundamental for maintaining the structural integrity of various tissues throughout the body.
Anatomy and Placement
Desmosomes involve several protein components. They feature an intracellular attachment plaque, a dense region just inside the cell membrane. This plaque is composed of proteins such as plakoglobin, plakophilins, and desmoplakin.
Extending from this plaque are specialized proteins called desmosomal cadherins, specifically desmogleins and desmocollins. These cadherins span the cell membrane and interlock with similar proteins from an adjacent cell, creating direct cell-to-cell adhesion. The complex is anchored to the cell’s intermediate filament network. These filaments, composed of keratin in epithelial cells and desmin in cardiac muscle cells, provide mechanical support and distribute forces across the tissue.
Desmosomes are found in tissues that endure mechanical stress and stretching. Prominent locations include the epidermis, the outer layer of the skin, and the myocardium, the muscle tissue of the heart. They are also present in the lining of blood vessels, lung air sacs, the esophagus, and bladder tissue. Their presence allows tissues to withstand physical forces without tearing.
Connecting the Body
The primary function of desmosomes is to provide cell-to-cell adhesion, which contributes to the mechanical strength of tissues. They link the cytoskeletal elements of one cell to another, forming a unified structural unit. This adhesion is important in tissues that undergo stretching, compression, or other forms of mechanical stress.
Desmosomes ensure cells remain attached, preventing them from pulling apart under strain. In the skin, desmosomes resist mechanical forces, maintaining epidermal integrity. In heart muscle, they are important for cardiac tissue integrity, especially during heart contractions.
This intercellular cohesion allows tissues to function as cohesive barriers and withstand physical demands. The intermediate filaments linked to desmosomes disperse forces throughout the tissue, enhancing its resilience. Without these connections, tissues would be susceptible to damage and disruption from everyday movements and pressures.
When Desmosomes Malfunction
When desmosomes do not function correctly, it can lead to conditions characterized by a loss of cell adhesion or impaired tissue integrity. These malfunctions can stem from genetic defects, autoimmune responses, or bacterial toxins. The specific symptoms depend on the affected tissues, reflecting their diverse distribution.
Skin blistering disorders, such as Pemphigus, result from desmosomal dysfunction. In Pemphigus, the immune system mistakenly produces autoantibodies that target desmosomal cadherins, specifically desmogleins 1 and 3. This autoimmune attack weakens cell-to-cell adhesion in the skin and mucous membranes, causing epidermal cells to separate and form fluid-filled blisters. The blisters are often fragile and rupture easily.
Another condition linked to desmosome defects is Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC), an inherited heart disease. ARVC is caused by mutations in genes that encode desmosomal proteins, such as plakoglobin, desmoplakin, and plakophilin 2. These mutations lead to a progressive loss of heart muscle cells, particularly in the right ventricle, which are then replaced by fatty and fibrous tissue. This cellular detachment and tissue remodeling disrupt the heart’s electrical signals, increasing the risk of life-threatening arrhythmias and sudden cardiac death.