EXPRESSION OF CATENINS DURING MOUSE EMBRYONIC-DEVELOPMENT AND IN ADULT TISSUES

Classical cadherins are cell-surface glycoproteins that mediate calciu m-dependent cell adhesion. The cytoplasmic domain of these glycoprotei ns is linked to the cytoskeleton through the catenins (alpha, beta and gamma). The catenins are intracellular polypeptides that are part of a complex sub-membranous network modulating the adhesive ability of th e cells. One approach to elucidate the role of these molecules in the cell is to investigate their distribution during mouse development and in adult tissues. This study reports that catenins are widely express ed but in varying amounts in embryos and adult tissues. The expression of all three catenins is most prominent in the adult heart muscle and in epithelia of all developmental stages. In other embryonic and adul t tissues, lower expression of catenins was detected, e.g., in smooth muscle or connective tissue. Catenins are coexpressed with various cad herins in different tissues. Gastrulation is the first time during emb ryogenesis when a discrepancy occurs between the expression of catenin s and E-cadherin. E-cadherin expression is suppressed in mesodermal ce lls but not the expression of catenins. This discrepancy suggests that another cadherin may interact with catenins. Similarly, E-cadherin is generally expressed in adult liver but not in the regions surrounding the central veins. In contrast, catenins are uniformly expressed in t he liver, suggesting that they are associated with other cadherins in E-cadherin negative cells. Finally, the three catenins are not always concurrently expressed. For example, in peripheral nerves, only beta-c atenin is observable, and in smooth muscle plakoglobin is not detectab le.