title: Intracellular localization of the cyclin-dependent kinase inhibitor p21CDKN1A-GFP fusion protein during cell cycle arrest.
abstract: The cyclin-dependent kinase (CDK) inhibitor p21CDKN1A is known to induce cell cycle arrest by inhibiting CDK activity and by interfering with DNA replication through binding to proliferating cell nuclear antigen. Although the molecular mechanisms have been elucidated, the temporal dynamics, as well as the intracellular sites of the activity of p21 bound to cyclin/CDK complexes during cell cycle arrest, have not been fully investigated. In this study we have induced the expression of p21CDKN1A fused to green fluorescent protein (GFP) in HeLa cells, in order to visualize the intracellular localization of the inhibitor during the cell cycle arrest. We show that p21-GFP is preferentially expressed in association with cyclin E in cells arrested in G1 phase, and with cyclin A more than with cyclin B1 in cells arrested in the G2/M compartment. In addition, we show for the first time that p21-GFP colocalizes with cyclin E in the nucleolus of HeLa cells during the G1 phase arrest.
authors.affiliation: Dipartimento di Medicina Sperimentale, sez. Patologia generale C. Golgi, Università di Pavia, Piazza Botta 10, 27100, Pavia, Italy.
authors.forename: Ornella
authors.initials: O
authors.lastname: Cazzalini
authors.forename: Paola
authors.initials: P
authors.lastname: Perucca
authors.forename: Federica
authors.initials: F
authors.lastname: Valsecchi
authors.forename: Lucia A
authors.initials: LA
authors.lastname: Stivala
authors.forename: Livia
authors.initials: L
authors.lastname: Bianchi
authors.forename: Vanio
authors.initials: V
authors.lastname: Vannini
authors.forename: Ennio
authors.initials: E
authors.lastname: Prosperi
mesh_terms: D002453:Cell Cycle / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology; D002466:Cell Nucleolus / Q000737:chemistry / Q000378:metabolism; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism; D019925:Cyclin A / Q000032:analysis / Q000378:metabolism; D019926:Cyclin B / Q000032:analysis / Q000378:metabolism; D056744:Cyclin B1; D019927:Cyclin E / Q000032:analysis / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21; D005434:Flow Cytometry; D016193:G1 Phase / Q000502:physiology; D016195:G2 Phase / Q000502:physiology; D015870:Gene Expression; D005822:Genetic Vectors / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016196:S Phase / Q000502:physiology; D014162:Transfection
chemical_list: C534699:CCNB1 protein, human; C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D002843:Chromatin; D019925:Cyclin A; D019926:Cyclin B; D056744:Cyclin B1; D019927:Cyclin E; D050759:Cyclin-Dependent Kinase Inhibitor p21; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins