title: Drosophila melanogaster Cyclin G coordinates cell growth and cell proliferation.
abstract: Mammalian Cyclins G1 and G2 are unconventional cyclins whose role in regulating the cell cycle is ambiguous. Cyclin G1 promotes G2/M cell cycle arrest in response to DNA damage whereas ectopic expression of CCNG2, that encodes Cyclin G2, induces G1/S cell cycle arrest. The only Drosophila Cyclin G was previously shown to be a transcriptional regulator that interacts with the chromatin factor Corto and controls expression of the homeotic gene Abdominal B. It is very close to mammalian Cyclin G1 and G2 except in its N-terminal region, that interacts with Corto, and that seems to have been acquired in dipterans. Ubiquitous misregulation of Cyclin G (CycG) using transgenic lines lengthens development and induces phenotypes suggesting growth or proliferation defects. Using tissue-specific misregulation of CycG and FACS, we show that overproduction of Cyclin G produces small cells whereas shortage produces large cells, suggesting that Cyclin G negatively regulates cell growth. Furthermore, overexpression of CycG lengthens the cell cycle, with a prominent effect on G1 and S phases. Genetic interactions with Cyclin E suggest that Cyclin G prevents G1 to S transition and delays S phase progression. Control of cell growth and cell cycle by Cyclin G might be achieved via interaction with a network of partners, notably the cyclin-dependent kinases CDK4 and CDK2.
authors.affiliation: Laboratoire de Biologie du Développement UMR 7622, Université Pierre et Marie Curie-Paris 6, Centre National de la Recherche Scientifique, Paris, France.
authors.forename: Floria
authors.initials: F
authors.lastname: Faradji
authors.forename: Sébastien
authors.initials: S
authors.lastname: Bloyer
authors.forename: Delphine
authors.initials: D
authors.lastname: Dardalhon-Cuménal
authors.forename: Neel B
authors.initials: NB
authors.lastname: Randsholt
authors.forename: Frédérique
authors.initials: F
authors.lastname: Peronnet
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D049109:Cell Proliferation; D048429:Cell Size; D056746:Cyclin G / Q000235:genetics / Q000378:metabolism*; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism; D004331:Drosophila melanogaster / Q000378:metabolism*; D005260:Female; D016193:G1 Phase; D008297:Male; D008969:Molecular Sequence Data; D010641:Phenotype; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D016196:S Phase; D016415:Sequence Alignment
chemical_list: D056746:Cyclin G; D034741:RNA, Small Interfering; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4