所属 川崎医療福祉大学 医療福祉学部 臨床心理学科 職種 特任教授
|表題||Piwi expression in archeocytes and choanocytes in demosponges: insights into the stem cell system in demosponges.|
|掲載誌名||正式名：Evolution & development|
略 称：Evol Dev
|著者・共著者||Funayama Noriko, Nakatsukasa Mikiko, Mohri Kurato, Masuda Yoshiki, Agata Kiyokazu|
|概要||Little is known about the stem cells of organisms early in metazoan evolution. To characterize the stem cell system in demosponges, we identified Piwi homologs of a freshwater sponge, Ephydatia fluviatilis, as candidate stem cell (archeocyte) markers. EfPiwiA mRNA was expressed in cells with archeocyte cell morphological features. We demonstrated that these EfPiwiA-expressing cells were indeed stem cells by showing their ability to proliferate, as indicated by BrdU-incorporation, and to differentiate, as indicated by the coexpression of EfPiwiA with cell-lineage-specific genes in presumptive committed archeocytes. EfPiwiA mRNA expression was maintained in mature choanocytes forming chambers, in contrast to the transition of gene expression from EfPiwiA to cell-lineagespecific markers during archeocyte differentiation into other cell types. Choanocytes are food-entrapping cells with morphological features similar to those of choanoflagellates (microvillus collar and a flagellum). Their known abilities to transform into archeocytes under specific circumstances and to give rise to gametes (mostly sperm) indicate that even when they are fully differentiated, choanocytes maintain pluripotent stem cell-like potential. Based on the specific expression of EfPiwiA in archeocytes and choanocytes, combined with
previous studies, we propose that both archeocytes and choanocytes are components of the demosponge stem cell system. We discuss the possibility that choanocytes might
represent the ancestral stem cells, whereas archeocytes might represent stem cells that further evolved in ancestral multicellular organisms.