title: ATM kinase activity modulates Fas sensitivity through the regulation of FLIP in lymphoid cells.
abstract: Ataxia telangiectasia (A-T) is a rare cancer-predisposing genetic disease, caused by the lack of functional ATM kinase, a major actor of the double strand brakes (DSB) DNA-damage response. A-T patients show a broad and diverse phenotype, which includes an increased rate of lymphoma and leukemia development. Fas-induced apoptosis plays a fundamental role in the homeostasis of the immune system and its defects have been associated with autoimmunity and lymphoma development. We therefore investigated the role of ATM kinase in Fas-induced apoptosis. Using A-T lymphoid cells, we could show that ATM deficiency causes resistance to Fas-induced apoptosis. A-T cells up-regulate FLIP protein levels, a well-known inhibitor of Fas-induced apoptosis. Reconstitution of ATM kinase activity was sufficient to decrease FLIP levels and to restore Fas sensitivity. Conversely, genetic and pharmacologic ATM kinase inactivation resulted in FLIP protein up-regulation and Fas resistance. Both ATM and FLIP are aberrantly regulated in Hodgkin lymphoma. Importantly, we found that reconstitution of ATM kinase activity decreases FLIP protein levels and restores Fas sensitivity in Hodgkin lymphoma-derived cells. Overall, these data identify a novel molecular mechanism through which ATM kinase may regulate the immune system homeostasis and impair lymphoma development.
authors.affiliation: Dulbecco Telethon Institute, Department of Experimental Medicine and Biochemical Sciences, University of Rome Tor Vergata, Italy.
authors.forename: Venturina
authors.initials: V
authors.lastname: Stagni
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: di Bari
authors.forename: Silvia
authors.initials: S
authors.lastname: Cursi
authors.forename: Ivano
authors.initials: I
authors.lastname: Condò
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Cencioni
authors.forename: Roberto
authors.initials: R
authors.lastname: Testi
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Lerenthal
authors.forename: Enrico
authors.initials: E
authors.lastname: Cundari
authors.forename: Daniela
authors.initials: D
authors.lastname: Barilà
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001260:Ataxia Telangiectasia; D064007:Ataxia Telangiectasia Mutated Proteins; D015551:Autoimmunity / Q000235:genetics; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D053903:DNA Breaks, Double-Stranded; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006689:Hodgkin Disease / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006706:Homeostasis / Q000235:genetics; D006801:Humans; D007938:Leukemia / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008214:Lymphocytes / Q000378:metabolism* / Q000473:pathology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019014:fas Receptor / Q000235:genetics / Q000378:metabolism*
chemical_list: D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D025521:Tumor Suppressor Proteins; D019014:fas Receptor; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases