Significantly, the various Dact genes show similar expression patterns, suggesting that in a given tissue, the regulation of Wnt and TgfB signaling will depend on the combinatorial action of Dact proteins. Results Searches for Dact genes in the animal kingdom Identification of new members of the gnathostomeDact gene family Currently, three Dact family selleck chem Tofacitinib members are known in mouse and humans, two Dact genes have been identified in the chicken, one in Xenopus and two in the zebrafish. In order to obtain a comprehensive overview of Dact genes in jawed vertebrates, we searched the genomes of various lobe finned lobe limbed and ray finned bony vertebrates. In our search we also included the genomic database for the elephant shark, a cartilaginous vertebrate.
To perform these searches, we interrogated the Ensembl and NCBI databases using the known human, mouse, chicken, Xenopus laevis and zebrafish Dact protein sequences as queries. Moreover, we performed searches with protein sequences encoded by individual exons or we used known Dact protein motifs. Since some of the selected genomes are not fully characterized, we also used the query sequences to interrogate the NCBI expressed sequence tags database for the aforementioned groups, for additional bony vertebrates and for the spiny dogfish shark, Pacific electric ray and little skate. The organisms searched in this study are listed in Additional file 1. the accession numbers of sequences are provided in Additional file 2, the results of our searches are shown in Figure 1.
The searches revealed that like mouse and humans, all mammals carried three Dact genes and all birds had two. In amphibians, we discovered a previously not recognized dact gene, increasing the complement of Dact genes in these animals to two as well. Remarkably, four distinct Dact genes were found in lizards and snakes, in turtles and in the coelacanth, while five dact genes were present in the gar as well as in the Tilapia, Medaka and the Atlantic cod, six in zebrafish, four in the stickleback and in pufferfish. These newly discovered genes indicate that the gnathostome Dact gene family is larger than previously anticipated. In order to ensure that all gnathostome Dact family members were traced, we repeated the searches, using the newly discovered sequences as queries. These searches, how ever, did not produce any further hits and confirmed the earlier results.
Based on similarities in sequence and organization, the Dact genes identified in sarcopterygians and acti Brefeldin_A nopterygians fell into four paralog groups. Matching sequences for all four paralog groups were found in chondrichthyans, indicating that four Dacts genes were present in the ancestral gnathostome genome. The first group encompassed known Dact1 sequences and their newly identified relatives.