title: AICAR induces Bax/Bak-dependent apoptosis through upregulation of the BH3-only proteins Bim and Noxa in mouse embryonic fibroblasts.
abstract: 5-Aminoimidazole-4-carboxamide (AICA) riboside (AICAR) is a nucleoside analogue that is phosphorylated to 5-amino-4-imidazolecarboxamide ribotide (ZMP), which acts as an AMP mimetic and activates AMP-activated protein kinase (AMPK). It has been recently described that AICAR triggers apoptosis in chronic lymphocytic leukemia (CLL) cells, and its mechanism of action is independent of AMPK as well as p53. AICAR-mediated upregulation of the BH3-only proteins BIM and NOXA correlates with apoptosis induction in CLL cells. Here we propose mouse embryonic fibroblasts (MEFs) as a useful model to analyze the mechanism of AICAR-induced apoptosis. ZMP formation was required for AICAR-induced apoptosis, though direct Ampk activation with A-769662 failed to induce apoptosis in MEFs. AICAR potently induced apoptosis in Ampkα1 (-/-) /α2 (-/-) MEFs, demonstrating an Ampk-independent mechanism of cell death activation. In addition, AICAR acts independently of p53, as MEFs lacking p53 also underwent apoptosis normally. Notably, MEFs lacking Bax and Bak were completely resistant to AICAR-induced apoptosis, confirming the involvement of the mitochondrial pathway in its mechanism of action. Apoptosis was preceded by ZMP-dependent but Ampk-independent modulation of the mRNA levels of different Bcl-2 family members, including Noxa, Bim and Bcl-2. Bim protein levels were accumulated upon AICAR treatment of MEFs, suggesting its role in the apoptotic process. Strikingly, MEFs lacking both Bim and Noxa displayed high resistance to AICAR. These findings support the notion that MEFs are a useful system to further dissect the mechanism of AICAR-induced apoptosis.
authors.affiliation: Departament de Ciències Fisiològiques II, Institut d'Investigació Biomèdica de Bellvitge IDIBELL-Universitat de Barcelona, Campus de Bellvitge, Pavelló de Govern, 4ª planta, L'Hospitalet de Llobregat, 08907 Barcelona, Catalonia, Spain.
authors.forename: Diana M
authors.initials: DM
authors.lastname: González-Gironès
authors.forename: Cristina
authors.initials: C
authors.lastname: Moncunill-Massaguer
authors.forename: Daniel
authors.initials: D
authors.lastname: Iglesias-Serret
authors.forename: Ana M
authors.initials: AM
authors.lastname: Cosialls
authors.forename: Alba
authors.initials: A
authors.lastname: Pérez-Perarnau
authors.forename: Claudia M
authors.initials: CM
authors.lastname: Palmeri
authors.forename: Camila
authors.initials: C
authors.lastname: Rubio-Patiño
authors.forename: Andreas
authors.initials: A
authors.lastname: Villunger
authors.forename: Gabriel
authors.initials: G
authors.lastname: Pons
authors.forename: Joan
authors.initials: J
authors.lastname: Gil
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics* / Q000378:metabolism; D000072224:Bcl-2-Like Protein 11; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics* / Q000378:metabolism; D012265:Ribonucleotides; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000235:genetics / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; C494773:Bak1 protein, mouse; C494827:Bax protein, mouse; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D008565:Membrane Proteins; C408009:Pmaip1 protein, mouse; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012265:Ribonucleotides; D016159:Tumor Suppressor Protein p53; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D000620:Aminoimidazole Carboxamide; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide