title: Posterior elongation in the annelid Platynereis dumerilii involves stem cells molecularly related to primordial germ cells.
abstract: Like most bilaterian animals, the annelid Platynereis dumerilii generates the majority of its body axis in an anterior to posterior temporal progression with new segments added sequentially. This process relies on a posterior subterminal proliferative body region, known as the "segment addition zone" (SAZ). We explored some of the molecular and cellular aspects of posterior elongation in Platynereis, in particular to test the hypothesis that the SAZ contains a specific set of stem cells dedicated to posterior elongation. We cloned and characterized the developmental expression patterns of orthologs of 17 genes known to be involved in the formation, behavior, or maintenance of stem cells in other metazoan models. These genes encode RNA-binding proteins (e.g., tudor, musashi, pumilio) or transcription factors (e.g., myc, id, runx) widely conserved in eumetazoans. Most of these genes are expressed both in the migrating primordial germ cells and in overlapping ring-like patterns in the SAZ, similar to some previously analyzed genes (piwi, vasa). The SAZ patterns are coincident with the expression of proliferation markers cyclin B and PCNA. EdU pulse and chase experiments suggest that new segments are produced through many rounds of divisions from small populations of teloblast-like posterior stem cells. The shared molecular signature between primordial germ cells and posterior stem cells in Platynereis thus corresponds to an ancestral "stemness" program.
authors.affiliation: Institut Jacques Monod, CNRS, UMR 7592, Univ Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France. Electronic address: gazave.eve@ijm.univ-paris-diderot.fr.
authors.forename: Eve
authors.initials: E
authors.lastname: Gazave
authors.forename: Julien
authors.initials: J
authors.lastname: Béhague
authors.forename: Lucie
authors.initials: L
authors.lastname: Laplane
authors.forename: Aurélien
authors.initials: A
authors.lastname: Guillou
authors.forename: Laetitia
authors.initials: L
authors.lastname: Préau
authors.forename: Adrien
authors.initials: A
authors.lastname: Demilly
authors.forename: Guillaume
authors.initials: G
authors.lastname: Balavoine
authors.forename: Michel
authors.initials: M
authors.lastname: Vervoort
mesh_terms: D000818:Animals; D000845:Annelida / Q000166:cytology* / Q000235:genetics / Q000254:growth & development*; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D004475:Ectoderm / Q000166:cytology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D005854:Germ Cells / Q000166:cytology* / Q000378:metabolism; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism; D012038:Regeneration; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism
keywords: Annelids; Posterior elongation; Segmentation; Stem cells; Stemness genes