title: Cell cycle regulation of the mammalian CDK activator RINGO/Speedy A.
abstract: Cell cycle progression is regulated by cyclin-dependent kinases (CDKs), whose activation requires the binding of regulatory subunits named cyclins. RINGO/Speedy A is a mammalian protein that has no amino acid sequence homology with cyclins but can activate CDKs. Here we show that RINGO/Speedy A is a highly unstable protein whose expression and phosphorylation are periodically regulated during the cell cycle. RINGO/Speedy A is degraded by the proteasome and the process involves the ubiquitin ligase SCF(Skp2). Overexpression of a stabilized RINGO/Speedy A form results in the accumulation of high levels of RINGO/Speedy A at late stages of mitosis, which interfere with cytokinesis and chromosome decondensation. Our data show that tight regulation of RINGO/Speedy A is important for the somatic cell cycle.
authors.affiliation: CNIO (Spanish National Cancer Center), Madrid, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Dinarina
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Santamaria
authors.forename: Angel R
authors.initials: AR
authors.lastname: Nebreda
mesh_terms: D000818:Animals; D015703:Antigens, CD; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D064199:Cdc20 Proteins; D002453:Cell Cycle / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D044786:S-Phase Kinase-Associated Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D044786:S-Phase Kinase-Associated Proteins; C486530:SPDYA protein, human; C577488:CDC20 protein, human; D018844:Cyclin-Dependent Kinases