desmosomes

Definition: Specialized cell junctions that are formed by desmosomal cadherins and additional associated proteins into which intermediate filaments are inserted. Also known as macula adherens junctions or spot desmosomes.

Desmosomes are essential adhesion structures in most epithelia that link the intermediate filament network of one cell to its neighbor, thereby forming a strong bond.

Desmosomes are the most common type of intercellular junction in vertebrate epithelial cells. They are characterized by 2 forms of interaction with other cellular structures.

First, they form membrane anchorage sites for intermediate-size filaments, which are seen as electron-dense plaques evident beneath the plasma membrane.

Second, a specific membrane core domain interacts with a corresponding domain of the plasma membrane of an adjacent cell, apparently mediating intercellular adhesion in a stable way.

The desmosome intermediate filament complex is thought to impart tensile strength and resilience to the epithelium.

Desmosomal proteins can be divided into 2 groups based on whether they fractionate with the urea-insoluble ’core’ or the urea-soluble ’plaque’ components. Desmoglein (MIM.125670) is, for example, a protein of the core. The main proteins of the plaque comprise the desmoplakins and plakoglobin (MIM.173325).

Components

 cadherin superfamily (desmosomal cadherins)(MIM.114020)

• desmogleins (MIM.125670)
• desmocollins (MIM.125643)

 plakin family (MIM.125647)

• armadillo repeat protein family (MIM.602269)
• plakophilin

 pinin (MIM.603154)

 desmoplakins (desmoplakin-1 and desmoplakin-2)(MIM.125647)

Molecular pathology of desmosomes

 pemphigus foliaceum: inactivation of desmoglein-1 by an autoantibody
 type I striate palmoplantaris keratosis: inactivation of desmoglein-1 by genic mutation
 pemphigus vulgaris: inactivation of desmoglein-3 by an autoantibody
 localized autosomal recessive hypotrichosis (LAH): inactivation of desmoglein-4 by genic mutation in (MIM.607903)
 type II striate palmoplantaris keratosis: inactivation of desmoplakin by genic mutation
 generalized striate keratoderma particularly affecting the palmoplantar epidermis, woolly hair, and a dilated left ventricular cardiomyopathy: inactivation of desmoplakin by genic mutation
 skin fragility-woolly hair syndrome (MIM.607655): inactivation of desmoplakin by genic mutation
 arrhythmogenic right ventricular dysplasia mapping to 6p24 (MIM.607450): inactivation of desmoplakin by genic mutation

References

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