Expression of Genes Coding for Cell-Cell Adhesion Proteins in Dictyostelium discoideum Mutants that Form Small Fruiting Bodies

In the cellular slime mold Dictyostelium discoideum, Countin2 and Countin3 proteins are thought to limit the minimum size of the multicellular structure since countin2- and countin3- strains form small fruiting bodies. Expression levels of the cell-cell adhesion proteins, gp24 and gp80, in wild type and null mutants were compared. During the process of aggregation, countin2- cells expressed lower levels of gp24 and gp80 than those expressed by the wild type. The expression levels of gp24 and gp80 in countin3- cells were almost the same as those in wild-type cells in the early stages of aggregation but were lower than wild-type levels in the late stages. These results indicate that Countin2 and Countin3 proteins enhance the expression of gp24 and gp80 in D. discoideum in different ways.