Medaka as a model system for the characterisation of cell cycle regulators: a functional analysis of Ol-Gadd45gamma during early embryogenesis.
Numerous studies, mostly performed on mammalian cell cultures, have implicated the Gadd45 family of small acidic proteins in cell cycle control (arrest and/or engagement in the apoptotic pathway). We report here the cloning, detailled expression pattern and functional characterisation in embryonic development of Ol-Gadd45gamma, the Oryzias latipes ortholog of mammalian Gadd45gamma. Its expression pattern, notably in the developing brain (optic tectum) strongly suggests that it is involved in cell cycle exit. Gain-of-function experiments (through mRNA injection) slowed down early development, and produced embryos clearly reduced in size, while morpholino knockdowns resulted in small embryos over-sensitive to DNA damage (UV irradiation). We further demonstrated that, following Ol-Gadd45gamma overexpression, cells are proliferation-arrested before both G1/S and G2/M cell cycle checkpoints, while in the MO-Ol-Gadd45 loss-of-function experiments cells are engaged in apoptosis rather than prevented from proliferating. These results show that Ol-Gadd45gamma is likely to play an important role in coordinating cell fate decisions during neurogenesis; they also demonstrate that the medakafish is a promising model to analyse in vivo the developmental control of the cell cycle.
Candal
Eva
E
INRA/CNRS Group, DEPSN, Institut Fessard, CNRS, 1 Avenue de la Terrasse, 91 198 Gif-sur-Yvette, France. candal@iaf.cnrs-gif.fr
Thermes
Violette
V
Joly
Jean-Stéphane
JS
Bourrat
Franck
F
D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology*; D004247:DNA / Q000378:metabolism; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D009990:Oryzias / Q000196:embryology* / Q000235:genetics; D010802:Phylogeny; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D000097642:GADD45 Proteins
D004247:DNA; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D000097642:GADD45 Proteins