title: Inactivation of Rb and E2f8 synergizes to trigger stressed DNA replication during erythroid terminal differentiation.
abstract: Rb is critical for promoting cell cycle exit in cells undergoing terminal differentiation. Here we show that during erythroid terminal differentiation, Rb plays a previously unappreciated and unorthodox role in promoting DNA replication and cell cycle progression. Specifically, inactivation of Rb in erythroid cells led to stressed DNA replication, increased DNA damage, and impaired cell cycle progression, culminating in defective terminal differentiation and anemia. Importantly, all of these defects associated with Rb loss were exacerbated by the concomitant inactivation of E2f8. Gene expression profiling and chromatin immunoprecipitation (ChIP) revealed that Rb and E2F8 cosuppressed a large array of E2F target genes that are critical for DNA replication and cell cycle progression. Remarkably, inactivation of E2f2 rescued the erythropoietic defects resulting from Rb and E2f8 deficiencies. Interestingly, real-time quantitative PCR (qPCR) on E2F2 ChIPs indicated that inactivation of Rb and E2f8 synergizes to increase E2F2 binding to its target gene promoters. Taken together, we propose that Rb and E2F8 collaborate to promote DNA replication and erythroid terminal differentiation by preventing E2F2-mediated aberrant transcriptional activation through the ability of Rb to bind and sequester E2F2 and the ability of E2F8 to compete with E2F2 for E2f-binding sites on target gene promoters.
authors.affiliation: Department of Microbiology and Molecular Genetics, Rutgers New Jersey Medical School Cancer Center, Newark, New Jersey, USA.
authors.forename: Seda
authors.initials: S
authors.lastname: Ghazaryan
authors.affiliation: Department of Microbiology and Molecular Genetics, Rutgers New Jersey Medical School Cancer Center, Newark, New Jersey, USA.
authors.forename: Chandler
authors.initials: C
authors.lastname: Sy
authors.affiliation: Department of Microbiology and Molecular Genetics, Rutgers New Jersey Medical School Cancer Center, Newark, New Jersey, USA.
authors.forename: Tinghui
authors.initials: T
authors.lastname: Hu
authors.affiliation: Membrane Biology Laboratory, New York Blood Center, New York, New York, USA.
authors.forename: Xiuli
authors.initials: X
authors.lastname: An
authors.affiliation: Red Cell Physiology Laboratory, New York Blood Center, New York, New York, USA.
authors.forename: Narla
authors.initials: N
authors.lastname: Mohandas
authors.affiliation: Laboratory of Molecular Pharmacology, National Cancer Institute, Bethesda, Maryland, USA.
authors.forename: Haiqing
authors.initials: H
authors.lastname: Fu
authors.affiliation: Laboratory of Molecular Pharmacology, National Cancer Institute, Bethesda, Maryland, USA.
authors.forename: Mirit I
authors.initials: MI
authors.lastname: Aladjem
authors.affiliation: Section of Hematology Oncology, VA New Jersey Health Care System, East Orange, New Jersey, USA.
authors.forename: Victor T
authors.initials: VT
authors.lastname: Chang
authors.affiliation: Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA.
authors.forename: Rene
authors.initials: R
authors.lastname: Opavsky
authors.affiliation: Department of Microbiology and Molecular Genetics, Rutgers New Jersey Medical School Cancer Center, Newark, New Jersey, USA wuli@njms.rutgers.edu.
authors.forename: Lizhao
authors.initials: L
authors.lastname: Wu
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D041905:Erythroid Cells / Q000378:metabolism*; D004920:Erythropoiesis / Q000235:genetics; D020869:Gene Expression Profiling / Q000379:methods; D051379:Mice; D018345:Mice, Knockout; D011401:Promoter Regions, Genetic / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism*; D012175:Retinoblastoma / Q000235:genetics* / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C504722:E2F8 protein, mouse; D012097:Repressor Proteins