Studio dei fattori di crescita coinvolti nello sviluppo tissutale e nella deposizione di matrice extracellulare del porifero Chondrosia reniformis (Nardo, 1847) con metodi immunoistochimici e di biologia molecolare.

Tissue repair is an adaptive and common metazoan response characterized by various cellular mechanisms and complex signalling networks that involve several growth factors and cytokines. In higher animals, the transforming growth factor-β superfamily members (TGF-β SF) signalling plays a fundamental role in wound healing. Aim of this thesis was to assess the involvement of TGF-β SF members in lower invertebrate tissue regeneration. To achieve this result, sequence that code for putative TGF ligands and receptors were isolated from the transcriptome of a marine sponge Chondrosia reniformis, transcriptome that was previously obtained in the laboratory hosting the research object of this doctorate’s work. C. reniformis is a marine Demospongiae, without siliceous spicules, but with a robust collagen scaffold. Since its identification as a true poriferous by Giovanni Domenico Nardo in the 1847, it has been the subject of study by zoologists, ecologists and more recently biotechnologists interested in several of its biological peculiarities. In the first part of the research we identified six transcripts that coded for TGF superfamily ligands and two sequences that coded for TGF superfamily receptors. Phylogenetically, the TGF ligands of C. reniformis could not be grouped in a TGF-β SF clades and consequently these ligands presumably evolved independently, while the TGF receptors clustered in the Type I receptor group. During the research activities we examined the gene expression of these transcripts and the cell regeneration processes from a microscopic morphological point of view in a particular type of sponge regenerating tissue explants called fragmorph. The fragmorphs are essentially coring, in our case of 9 millimeters in diameter, made perpendicularly to the upper face of the sponge. The data obtained indicated that three ligands (TGF-1, -3 and -6) could be involved in staminal cell maintenance, since they were mainly expressed during early regeneration, while two (TGF-4 and TGF-5) were considered pro-differentiating factors, since they were strongly upregulated during late regeneration. In presence of 0.1mM SB431542, a strong TGF receptors inhibitor, the exopinacoderm restoring of the fragmorph resulted blocked, attesting the functional involvement of TGF-pathway in tissue regeneration also in these early evolved animals.