title: Functional genetic screen for genes involved in senescence: role of Tid1, a homologue of the Drosophila tumor suppressor l(2)tid, in senescence and cell survival.
abstract: We performed a genetic suppressor element screen to identify genes whose inhibition bypasses cellular senescence. A normalized library of fragmented cDNAs was used to select for elements that promote immortalization of rat embryo fibroblasts. Fragments isolated by the screen include those with homology to genes that function in intracellular signaling, cellular adhesion and contact, protein degradation, and apoptosis. They include mouse Tid1, a homologue of the Drosophila tumor suppressor gene l(2)tid, recently implicated in modulation of apoptosis as well as gamma interferon and NF-kappaB signaling. We show that GSE-Tid1 enhances immortalization by human papillomavirus E7 and simian virus 40 T antigen and cooperates with activated ras for transformation. Expression of Tid1 is upregulated upon cellular senescence in rat and mouse embryo fibroblasts and premature senescence of REF52 cells triggered by activated ras. In accordance with this, spontaneous immortalization of rat embryo fibroblasts is suppressed upon ectopic expression of Tid1. Modulation of endogenous Tid1 activity by GSE-Tid1 or Tid1-specific RNA interference alleviates the suppression of tumor necrosis factor alpha-induced NF-kappaB activity by Tid1. We also show that NF-kappaB sequence-specific binding is strongly downregulated upon senescence in rat embryo fibroblasts. We therefore propose that Tid1 contributes to senescence by acting as a repressor of NF-kappaB signaling.
authors.affiliation: Ludwig Institute for Cancer Research, 91 Riding House St., London W1W 7BS, United Kingdom.
authors.forename: Marina
authors.initials: M
authors.lastname: Tarunina
authors.forename: Lynsey
authors.initials: L
authors.lastname: Alger
authors.forename: Grace
authors.initials: G
authors.lastname: Chu
authors.forename: Karl
authors.initials: K
authors.lastname: Munger
authors.forename: Andrei
authors.initials: A
authors.lastname: Gudkov
authors.forename: Parmjit S
authors.initials: PS
authors.lastname: Jat
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002470:Cell Survival / Q000235:genetics*; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000235:genetics*; D024202:Electrophoretic Mobility Shift Assay; D004622:Embryo, Mammalian / Q000166:cytology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D017930:Genes, Reporter; D005839:Gentamicins / Q000494:pharmacology; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D018832:Molecular Chaperones / Q000235:genetics / Q000502:physiology*; D016328:NF-kappa B / Q000502:physiology; D011506:Proteins / Q000032:analysis / Q000378:metabolism; D012313:RNA / Q000032:analysis / Q000378:metabolism; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D012190:Retroviridae / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D000900:Anti-Bacterial Agents; C485636:Dnaja3 protein, mouse; D005839:Gentamicins; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D016328:NF-kappa B; D011506:Proteins; D014409:Tumor Necrosis Factor-alpha; D025521:Tumor Suppressor Proteins; D012313:RNA; C010680:antibiotic G 418; D008156:Luciferases