BACKGROUND: Piwi proteins are essential for germ line development, stem cell maintenance, and more recently found to function in epigenetic and somatic gene regulation. In the sea urchin Strongylocentrotus purpuratus, two Piwi proteins, Seawi and Piwi-like1, have been identified, yet their functional contributions have not been reported. RESULTS: Here we found that Seawi protein was localized uniformly in the early embryo and then became enriched in the primordial germ cells (PGCs) (the small micromere lineage) from blastula stage and thereafter. Morpholino knockdown of Sp-seawi diminished PGC-specific localization of Seawi proteins, and altered expression of other germ line markers such as Vasa and Gustavus, but had no effect on Nanos. Furthermore, Seawi knockdown transiently resulted in Vasa positive cell proliferation in the right coelomic pouch that appear to be derived from the small micromere lineage, yet they quickly disappeared with an indication of apoptosis by larval stage. Severe Seawi knockdown resulted in an increased number of apoptotic cells in the entire gut area. CONCLUSION: Piwi proteins appear to regulate PGC proliferation perhaps through control of Vasa accumulation. In this organism, Piwi is likely regulating mRNAs, not just transposons, and is potentially functioning both inside and outside of the germ line during embryogenesis.
BACKGROUND: Piwi proteins are essential for germ line development, stem cell maintenance, and more recently found to function in epigenetic and somatic gene regulation. In the sea urchin Strongylocentrotus purpuratus, two Piwi proteins, Seawi and Piwi-like1, have been identified, yet their functional contributions have not been reported. RESULTS: Here we found that Seawi protein was localized uniformly in the early embryo and then became enriched in the primordial germ cells (PGCs) (the small micromere lineage) from blastula stage and thereafter. Morpholino knockdown of Sp-seawi diminished PGC-specific localization of Seawi proteins, and altered expression of other germ line markers such as Vasa and Gustavus, but had no effect on Nanos. Furthermore, Seawi knockdown transiently resulted in Vasa positive cell proliferation in the right coelomic pouch that appear to be derived from the small micromere lineage, yet they quickly disappeared with an indication of apoptosis by larval stage. Severe Seawi knockdown resulted in an increased number of apoptotic cells in the entire gut area. CONCLUSION: Piwi proteins appear to regulate PGC proliferation perhaps through control of Vasa accumulation. In this organism, Piwi is likely regulating mRNAs, not just transposons, and is potentially functioning both inside and outside of the germ line during embryogenesis.
Authors: Celina E Juliano; Ekaterina Voronina; Christie Stack; Maryanna Aldrich; Andrew R Cameron; Gary M Wessel Journal: Dev Biol Date: 2006-08-04 Impact factor: 3.582
Authors: Jia L Song; Marlon Stoeckius; Jonas Maaskola; Marc Friedländer; Nadezda Stepicheva; Celina Juliano; Svetlana Lebedeva; William Thompson; Nikolaus Rajewsky; Gary M Wessel Journal: Dev Biol Date: 2011-12-03 Impact factor: 3.582
Authors: Ekaterina Voronina; Manuel Lopez; Celina E Juliano; Eric Gustafson; Jia L Song; Cassandra Extavour; Sophie George; Paola Oliveri; David McClay; Gary Wessel Journal: Dev Biol Date: 2008-01-14 Impact factor: 3.582
Authors: S Zachary Swartz; Adrian M Reich; Nathalie Oulhen; Tal Raz; Patrice M Milos; Joseph P Campanale; Amro Hamdoun; Gary M Wessel Journal: Development Date: 2014-08 Impact factor: 6.868