title: Transient translational quiescence in primordial germ cells.
abstract: Stem cells in animals often exhibit a slow cell cycle and/or low transcriptional activity referred to as quiescence. Here, we report that the translational activity in the primordial germ cells (PGCs) of the sea urchin embryo (Strongylocentrotus purpuratus) is quiescent. We measured new protein synthesis with O-propargyl-puromycin and L-homopropargylglycine Click-iT technologies, and determined that these cells synthesize protein at only 6% the level of their adjacent somatic cells. Knockdown of translation of the RNA-binding protein Nanos2 by morpholino antisense oligonucleotides, or knockout of the Nanos2 gene by CRISPR/Cas9 resulted in a significant, but partial, increase (47%) in general translation specifically in the PGCs. We found that the mRNA of the translation factor eEF1A is excluded from the PGCs in a Nanos2-dependent manner, a consequence of a Nanos/Pumilio response element (PRE) in its 3'UTR. In addition to eEF1A, the cytoplasmic pH of the PGCs appears to repress translation and simply increasing the pH also significantly restores translation selectively in the PGCs. We conclude that the PGCs of this sea urchin institute parallel pathways to quiesce translation thoroughly but transiently.
authors.affiliation: Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting Street, 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 Street, Providence, RI 02912, USA.|Whitehead Institute for Biomedical Research, MIT, Nine Cambridge Center, Cambridge, MA 02142, USA.
authors.forename: S Zachary
authors.initials: SZ
authors.lastname: Swartz
authors.affiliation: Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting Street, Providence, RI 02912, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Laird
authors.affiliation: Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting Street, Providence, RI 02912, USA.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Mascaro
authors.affiliation: Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting Street, Providence, RI 02912, USA gary_wessel@brown.edu.
authors.forename: Gary M
authors.identifier: 0000-0002-1210-9279
authors.initials: GM
authors.lastname: Wessel
mesh_terms: D000818:Animals; D001483:Base Sequence; D036703:Blastula / Q000166:cytology / Q000378:metabolism; D064113:CRISPR-Cas Systems / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D005854:Germ Cells / Q000166:cytology* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008928:Mitochondria / Q000378:metabolism; D020648:Peptide Elongation Factor 1 / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D047270:Strongylocentrotus purpuratus / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*
chemical_list: D020648:Peptide Elongation Factor 1; D012333:RNA, Messenger; D016601:RNA-Binding Proteins
keywords: Metabolism; Primordial germ cells; Sea urchin; Translation