title: An RbAp48-like gene regulates adult stem cells in planarians.
abstract: Retinoblastoma-associated proteins 46 and 48 (RbAp46 and RbAp48) are factors that are components of different chromatin-modelling complexes, such as polycomb repressive complex 2, the activity of which is related to epigenetic gene regulation in stem cells. To date, no direct findings are available on the in vivo role of RbAp48 in stem-cell biology. We recently identified DjRbAp48 - a planarian (Dugesia japonica) homologue of human RBAP48 - expression of which is restricted to the neoblasts, the adult stem cells of planarians. In vivo silencing of DjRbAp48 induces lethality and inability to regenerate, even though neoblasts proliferate and accumulate after wounding. Despite a partial reduction in neoblast number, we were always able to detect a significant number of these cells in DjRbAp48 RNAi animals. Parallel to the decrease in neoblasts, a reduction in the number of differentiated cells and the presence of apoptotic-like neoblasts were detectable in RNAi animals. These findings suggest that DjRbAp48 is not involved in neoblast maintenance, but rather in the regulation of differentiation of stem-cell progeny. We discuss our data, taking into account the possibility that DjRbAp48 might control the expression of genes necessary for cell differentiation by influencing chromatin architecture.
authors.affiliation: Dipartimento di Morfologia Umana e Biologia Applicata, Università di Pisa, Pisa, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Bonuccelli
authors.forename: Leonardo
authors.initials: L
authors.lastname: Rossi
authors.forename: Annalisa
authors.initials: A
authors.lastname: Lena
authors.forename: Vittoria
authors.initials: V
authors.lastname: Scarcelli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Rainaldi
authors.forename: Monica
authors.initials: M
authors.lastname: Evangelista
authors.forename: Paola
authors.initials: P
authors.lastname: Iacopetti
authors.forename: Vittorio
authors.initials: V
authors.lastname: Gremigni
authors.forename: Alessandra
authors.initials: A
authors.lastname: Salvetti
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000502:physiology; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002843:Chromatin / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D005434:Flow Cytometry; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D046529:Microscopy, Electron, Transmission; D010932:Planarians / Q000166:cytology* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D034622:RNA Interference; D056505:Retinoblastoma-Binding Protein 4 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D002843:Chromatin; D015801:Helminth Proteins; C082637:RBBP4 protein, human; D056505:Retinoblastoma-Binding Protein 4