The complement of desmosomal plaque proteins in different cell types.

Area of Science:

• Cell Biology
• Protein Biochemistry
• Molecular Biology

Background:

• Desmosomes are crucial cell-cell adhesion structures found in various tissues.
• Desmosomal plaque proteins, including desmoplakins and band 5 protein, are key components of these structures.
• Understanding the expression patterns of these proteins is vital for comprehending desmosome function and tissue-specific roles.

Purpose of the Study:

• To investigate the presence and distribution of desmosomal plaque proteins, specifically desmoplakins I and II and band 5 protein, across different cell types and species.
• To determine if the composition of desmosomal plaques varies depending on the cell type.
• To elucidate the expression patterns of desmoplakin I, desmoplakin II, and band 5 protein in relation to tissue differentiation.

Main Methods:

• Utilized immunoblotting and immunolocalization techniques.
• Employed a panel of monoclonal antibodies against desmoplakins I and II and a guinea pig antiserum against desmosomal band 5 protein.
• Examined protein expression in various cell types, including stratified, simple, and pseudostratified epithelia, and myocardial tissue from different species.

Main Results:

• Proteins similar to desmoplakin I and band 5 protein were found in all examined desmosomes across diverse tissues.
• Desmoplakin II was detected exclusively in cells from stratified and pseudostratified epithelial tissues.
• Antibody reactivity revealed unique regions in desmoplakin I not present in desmoplakin II and varying species specificity.

Conclusions:

• The desmosomal plaque composition is cell-type specific, with desmoplakin II expression restricted to epithelial tissues.
• Desmoplakin I and band 5 protein are obligatory desmosomal plaque proteins expressed coordinately.
• The expression of desmoplakin I and band 5 protein is independent of other differentiation programs, such as those for epithelial or cardiac cells.