Interspecies conservation and differential expression of mouse desmoglein gene family

Epithelial cell adhesion is mediated by intercellular junctions, called desmosomes. Desmogleins (Dsg; Dsg1, Dsg2 and Dsg3) are calcium-dependent transmembrane adhesion components of the desmosomes. While Dsg1 and Dsg3 are mainly restricted to stratified squamous epithelia, Dsg2 is expressed in essentially all desmosome-containing epithelia. In the epidermis, Dsg2 and Dsg3 are expressed in the basal keratinocytes while Dsg1 is expressed throughout the upper differentiating cell layers. To date, in mouse, only Dsg3 has been characterized by molecular cloning. In this study, we have cloned and characterized the mouse Dsg1 and Dsg2 genes. The full-length mouse Dsg1 cDNA (5.5 kb) contains an open reading frame (ORF) of 3171 bp encoding a precursor protein of 1057 amino acids. The Dsg2 cDNA (6.3 kb) has an ORF of 3366 bp coding for a precursor protein of 1122 amino acids. Mouse Dsg2 protein shares 76% identity with human DSG2 but only 26% and 33% identity with mouse Dsg1 and Dsg3, respectively. Analysis of intron/exon organization of the desmoglein genes revealed significant conservation. However, the mRNA expression patterns of these desmogleins during mouse embryonic development and in various adult tissues are variable. While Dsg2 and Dsg3 are expressed in all developmental stages, Dsg1 expression is delayed until day 15 of mouse embryos. In adult mouse tissues, Dsg2 is widely expressed while the expression of Dsg1 and Dsg3 is restricted to select tissues. In summary, while desmogleins share high homology at both the gene and protein level, their expression is spatially and temporally regulated, potentially contributing to their significant role in cell-cell adhesion during development.