title: Aurora B kinase regulates the postmitotic endoreduplication checkpoint via phosphorylation of the retinoblastoma protein at serine 780.
abstract: The phenotypic change characteristic of Aurora B inhibition is the induction of polyploidy. Utilizing specific siRNA duplexes and a selective small molecule inhibitor (AZD1152) to inhibit Aurora B activity in tumor cells, we sought to elucidate the mechanism by which Aurora B inhibition results in polyploidy. Cells treated with AZD1152 progressed through mitosis with misaligned chromosomes and exited without cytokinesis and subsequently underwent endoreduplication of DNA despite activation of a p53-dependent pseudo G1 checkpoint. Concomitant with polyploid cell formation, we observed the appearance of Rb hypophosphorylation, an event that occurred independently of cyclin-dependent kinase inhibition. We went on to discover that Aurora B directly phosphorylates Rb at serine 780 both in vitro and in vivo. This novel interaction plays a critical role in regulating the postmitotic checkpoint to prevent endoreduplication after an aberrant mitosis. Thus, we propose for the first time that Aurora B determines cellular fate after an aberrant mitosis by directly regulating the Rb tumor suppressor protein.
authors.affiliation: Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
authors.forename: Jayasree S
authors.initials: JS
authors.lastname: Nair
authors.forename: Alan L
authors.initials: AL
authors.lastname: Ho
authors.forename: Archie N
authors.initials: AN
authors.lastname: Tse
authors.forename: Jesse
authors.initials: J
authors.lastname: Coward
authors.forename: Haider
authors.initials: H
authors.lastname: Cheema
authors.forename: Grazia
authors.initials: G
authors.lastname: Ambrosini
authors.forename: Nicholas
authors.initials: N
authors.lastname: Keen
authors.forename: Gary K
authors.initials: GK
authors.lastname: Schwartz
mesh_terms: D000595:Amino Acid Sequence; D064107:Aurora Kinase B; D064127:Aurora Kinases; D045325:HCT116 Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D008938:Mitosis / Q000187:drug effects; D008969:Molecular Sequence Data; D010755:Organophosphates / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000378:metabolism*; D011123:Polyploidy; D011485:Protein Binding / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011799:Quinazolines / Q000494:pharmacology; D016160:Retinoblastoma Protein / Q000737:chemistry / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: C520647:2-((3-((4-((5-(2-((3-fluorophenyl)amino)-2-oxoethyl)-1H-pyrazol-3-yl)amino)quinazolin-7-yl)oxy)propyl)(ethyl)amino)ethyl dihydrogen phosphate; D006657:Histones; D010755:Organophosphates; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D016160:Retinoblastoma Protein; D016159:Tumor Suppressor Protein p53; D010768:Phosphoserine; C576921:AURKB protein, human; D064107:Aurora Kinase B; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases