Evolutionarily conserved role of nucleostemin: controlling proliferation of stem/progenitor cells during early vertebrate development.
Nucleostemin (NS) is a putative GTPase expressed preferentially in the nucleoli of neuronal and embryonic stem cells and several cancer cell lines. Transfection and knockdown studies indicated that NS controls the proliferation of these cells by interacting with the p53 tumor suppressor protein and regulating its activity. To assess the physiological role of NS in vivo, we generated a mutant mouse line with a specific gene trap event that inactivates the NS allele. The corresponding NS(-/-) embryos died around embryonic day 4. Analyses of NS mutant blastocysts indicated that NS is not required to maintain pluripotency, nucleolar integrity, or survival of the embryonic stem cells. However, the homozygous mutant blastocysts failed to enter S phase even in the absence of functional p53. Haploid insufficiency of NS in mouse embryonic fibroblasts leads to decreased cell proliferation. NS also functions in early amphibian development to control cell proliferation of neural progenitor cells. Our results show that NS has a unique ability, derived from an ancestral function, to control the proliferation rate of stem/progenitor cells in vivo independently of p53.
Beekman
Chantal
C
Laboratory for Molecular Cancer Biology, Flanders Interuniversity Institute for Biotechnology (VIB), Technologiepark, 927, B-9052 Ghent, Belgium.
Nichane
Massimo
M
De Clercq
Sarah
S
Maetens
Marion
M
Floss
Thomas
T
Wurst
Wolfgang
W
Bellefroid
Eric
E
Marine
Jean-Christophe
JC
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D017124:Conserved Sequence; D010064:Embryo Implantation / Q000235:genetics; D053595:Embryonic Stem Cells / Q000502:physiology*; D019143:Evolution, Molecular; D005260:Female; D019204:GTP-Binding Proteins; D005804:Genes, Lethal / Q000502:physiology; D051379:Mice; D009474:Neurons / Q000166:cytology; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D016601:RNA-Binding Proteins; D029867:Xenopus Proteins / Q000502:physiology*; D014982:Xenopus laevis / Q000196:embryology
D002352:Carrier Proteins; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D029867:Xenopus Proteins; C470311:nucleostemin protein, mouse; D019204:GTP-Binding Proteins