title: Loss of Emi1-dependent anaphase-promoting complex/cyclosome inhibition deregulates E2F target expression and elicits DNA damage-induced senescence.
abstract: Expression of the anaphase-promoting complex/cyclosome (APC/C) inhibitor Emi1 is required for the accumulation of APC/C substrates crucial for DNA synthesis and mitotic entry. We show that in vivo Emi1 expression correlates with the proliferative status of the cellular compartment and that cells lacking Emi1 undergo cellular senescence. Emi1 depletion leads to strong decreases in E2F target mRNA and APC/C substrate protein abundances. However, cyclin E mRNA and cyclin E protein levels and associated kinase activities are increased. Cells lacking Emi1 undergo DNA damage, likely explained by replication stress upon deregulated cyclin E- and A-associated kinase activities. Inhibition of ATM kinase prevents induction of senescence, implying that senescence is a consequence of DNA damage. Surprisingly, no senescence or no extensive amount of senescence is evident upon depletion of the Emi1-stabilizing factor Evi5 or Pin1, respectively. Our data suggest that maintenance of a protein stabilization/mRNA expression positive-feedback circuit fueled by Emi1 is required for accurate cell cycle progression, maintenance of DNA integrity, and prevention of cellular senescence.
authors: Department of Tumor Biology and Angiogenesis, Genentech Inc., 1 DNA way, South San Francisco, California 94080, USA.
authors: Emmy W
authors: EW
authors: Verschuren
authors: Kenneth H
authors: KH
authors: Ban
authors: Marilyn A
authors: MA
authors: Masek
authors: Norman L
authors: NL
authors: Lehman
authors: Peter K
authors: PK
authors: Jackson
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins; D002460:Cell Line; D016922:Cellular Senescence; D019927:Cyclin E / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D050684:E2F Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D014018:Tissue Distribution; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D019927:Cyclin E; D050684:E2F Transcription Factors; C498959:Emi1 protein, mouse; C105043:Evi5 protein, mouse; D020690:GTPase-Activating Proteins; D011506:Proteins; D034741:RNA, Small Interfering; D014157:Transcription Factors; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome