ИСТИНА

Transforming growth factor beta pathway is one of the major signalling mechanisms that manage development of multicellular organisms together with Wnt, Hedgehog, Delta/Notch, tyrosine-kinase pathways. Axial patterning in embryo development is the brightest example of its role. Functions of TGF-beta pathway established early in evolution of multicellularity as ligands or receptors not found in Protista, whereas in Cnidaria this pathway determines the directive axis of the body. At the same time, TGF-beta expression data from sponges' development tell us about involvement of TGF-beta pathway in axial patterning of Porifera embryo. Number of ligands may be as many as eight in demosponge Amphimedon queenslandica or twenty-two in calcisponge Sycon ciliatum so sponges are not simple in sense of ligand repertoire in comparison to Bilateria. In this study we search through genome, analyzed in silica, cloned and described expression of ligands and receptors of TGF-beta superfamily in demosponge Halisarca dujardini. Eight ligands were identified, and their primary structure and domain organization correspond to eumetazoan TGF-beta . Three of eight identified ligands can be classified as TGF-beta sensu stricto when next five are not fall into any of eumetazoan family TGF- beta. Similar situation described for Wnt pathway ligands in sponges, and it shows independent involvement of some signalling pathways members inside Porifera phyla. Ouantitation of RNAseq data reveals increased expression levels of ligands in osculum of adult sponge. Asymmetric localization of ligand transcripts was described during embryogenesis. Our data suppose that TGF-beta pathway involved in axial patterning in as early branching Metazoa as sponges.