title: Gene expression of pluripotency determinants is conserved between mammalian and planarian stem cells.
abstract: Freshwater planaria possess extreme regeneration capabilities mediated by abundant, pluripotent stem cells (neoblasts) in adult animals. Although planaria emerged as an attractive in vivo model system for stem cell biology, gene expression in neoblasts has not been profiled comprehensively and it is unknown how molecular mechanisms for pluripotency in neoblasts relate to those in mammalian embryonic stem cells (ESCs). We purified neoblasts and quantified mRNA and protein expression by sequencing and shotgun proteomics. We identified ∼4000 genes specifically expressed in neoblasts, including all ∼30 known neoblast markers. Genes important for pluripotency in ESCs, including regulators as well as targets of OCT4, were well conserved and upregulated in neoblasts. We found conserved expression of epigenetic regulators and demonstrated their requirement for planarian regeneration by knockdown experiments. Post-transcriptional regulatory genes characteristic for germ cells were also enriched in neoblasts, suggesting the existence of a common ancestral state of germ cells and ESCs. We conclude that molecular determinants of pluripotency are conserved throughout evolution and that planaria are an informative model system for human stem cell biology.
authors.affiliation: Laboratory of Systems Biology of Gene Regulatory Elements, Max-Delbrück-Center for Molecular Medicine, Berlin, Germany.
authors.forename: Pinar
authors.initials: P
authors.lastname: Onal
authors.forename: Dominic
authors.initials: D
authors.lastname: Grün
authors.forename: Catherine
authors.initials: C
authors.lastname: Adamidi
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Rybak
authors.forename: Jordi
authors.initials: J
authors.lastname: Solana
authors.forename: Guido
authors.initials: G
authors.lastname: Mastrobuoni
authors.forename: Yongbo
authors.initials: Y
authors.lastname: Wang
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Rahn
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Stefan
authors.initials: S
authors.lastname: Kempa
authors.forename: Ulrike
authors.initials: U
authors.lastname: Ziebold
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Rajewsky
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D010932:Planarians / Q000166:cytology*; D039904:Pluripotent Stem Cells / Q000502:physiology*; D020543:Proteome / Q000032:analysis
chemical_list: D020543:Proteome