14-3-3 gene characterization and description of a second 14-3-3 isoform in both Echinococcus granulosus and E. multilocularis.

Members of the 14-3-3 protein family have been identified as regulatory molecules in intracellular signaling pathways and cell cycle control. Previously, the first Echinococcus 14-3-3 isoform (E14-3-3.1) was isolated from E. granulosus and E. multilocularis metacestode stages. Hyperexpression of this isoform was claimed to be associated with non-restricted tumor-like growth of the E. multilocularis metacestode. In this report, we describe the characterization of a 14-3-3 cDNA from E. granulosus and E. multilocularis corresponding to a second isoform of this family, E14-3-3.2. The characterized 14-3-3 gene was interrupted by two introns whose sequence and positions were conserved in both Echinococcus species. The deduced amino acid sequence of E14-3-3.2 showed 88% identity to the E14-3-3.1 isoform and 52% identity to a third Echinococcus isoform (E14-3-3.3) described by other authors. These findings, coupled to Southern blot analysis, suggest the presence of more than one 14-3-3 gene in Echinococcus. Phylogenenetically, the Echinococcus 14-3-3.1 and 14-3-3.2 isoforms appeared to cluster with zeta-type ("pro-tumorigenic") 14-3-3 isoforms from closely related organisms, whereas the E14-3-3.3 isoform grouped with 14-3-3 epsilon isoforms. The presence of more than one 14-3-3 isoform might indicate isoform-specific roles in the different parasite stages of Echinococcus.