title: Differential Nanos 2 protein stability results in selective germ cell accumulation in the sea urchin.
abstract: Nanos is a translational regulator required for the survival and maintenance of primordial germ cells. In the sea urchin, Strongylocentrotus purpuratus (Sp), Nanos 2 mRNA is broadly transcribed but accumulates specifically in the small micromere (sMic) lineage, in part because of the 3'UTR element GNARLE leads to turnover in somatic cells but retention in the sMics. Here we found that the Nanos 2 protein is also selectively stabilized; it is initially translated throughout the embryo but turned over in the future somatic cells and retained only in the sMics, the future germ line in this animal. This differential stability of Nanos protein is dependent on the open reading frame (ORF), and is independent of the sumoylation and ubiquitylation pathways. Manipulation of the ORF indicates that 68 amino acids in the N terminus of the Nanos protein are essential for its stability in the sMics whereas a 45 amino acid element adjacent to the zinc fingers targets its degradation. Further, this regulation of Nanos protein is cell autonomous, following formation of the germ line. These results are paradigmatic for the unique presence of Nanos in the germ line by a combination of selective RNA retention, distinctive translational control mechanisms (Oulhen et al., 2013), and now also by defined Nanos protein stability.
authors.affiliation: Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting St., Providence, RI 02912, USA.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Oulhen
authors.affiliation: Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting St., Providence, RI 02912, USA. Electronic address: rhet@brown.edu.
authors.forename: Gary M
authors.initials: GM
authors.lastname: Wessel
mesh_terms: D000818:Animals; D018507:Gene Expression Regulation, Developmental; D055786:Gene Knockout Techniques; D005854:Germ Cells / Q000378:metabolism*; D060172:Morpholinos; D016366:Open Reading Frames / Q000235:genetics*; D014176:Protein Biosynthesis / Q000235:genetics; D055550:Protein Stability; D012333:RNA, Messenger / Q000096:biosynthesis; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D013215:Starfish / Q000196:embryology; D047270:Strongylocentrotus purpuratus / Q000196:embryology*; D058207:Sumoylation; D054875:Ubiquitination
chemical_list: D060172:Morpholinos; D012333:RNA, Messenger; D016601:RNA-Binding Proteins
keywords: Cyclin B; Germ line; Nanos; Pumilio; Sea urchin; Small micromeres; Strongylocentrotus purpuratus; Sumo; Ubiquitin; Zinc finger