title: Cell permeable BH3-peptides overcome the cytoprotective effect of Bcl-2 and Bcl-X(L).
abstract: Peptides corresponding to the BH3 domains of Bax (BaxBH3) or Bcl-2 (Bcl2BH3) are potent inducers of apoptosis when fused to the Atennapedia plasma membrane translocation domain (Ant). BaxBH3Ant and Bcl2BH3Ant caused a mitochondrial membrane permeabilization (MMP) and apoptosis, via a mechanism that was not inhibited by overexpressed Bcl-2 or Bcl-X(L), yet partially inhibited by cyclosporin A (CsA), an inhibitor of the mitochondrial permeability transition pore. When added to isolated mitochondria, BaxBH3 and Bcl2BH3 induced MMP, which was inhibited by CsA. However, Bcl-2 or Bcl-X(L) failed to inhibit MMP induced by BaxBH3 and Bc2BH3 in vitro, while they efficiently suppressed the induction of MMP by the Vpr protein (from human immunodeficiency virus-1), a ligand of the adenine nucleotide translocator (ANT). BaxBH3 but not Bcl2BH3 was found to interact with ANT, and only BaxBH3 (not Bcl2BH3) permeabilized ANT proteoliposomes and induced ANT to form non-specific channels in electrophysiological experiments. In contrast, both BaxBH3 and Bcl2BH3 were able to stimulate channel formation by recombinant Bax protein. Thus, BaxBH3 might induce MMP via an action on at least two targets, ANT and Bax-like proteins. In contrast, Bcl2BH3 would elicit MMP in an ANT-independent fashion. In purified mitochondria, two ligands of ANT, bongkrekic acid and the protein vMIA from cytomegalovirus, failed to prevent MMP induced by BaxBH3 or Bcl2BH3. In conclusion, BaxBH3 and Bcl2BH3 induce MMP and apoptosis through a mechanism which overcomes cytoprotection by Bcl-2 and Bcl-X(L).
authors.affiliation: Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif, France.
authors.forename: Helena L A
authors.initials: HL
authors.lastname: Vieira
authors.forename: Patricia
authors.initials: P
authors.lastname: Boya
authors.forename: Isabelle
authors.initials: I
authors.lastname: Cohen
authors.forename: Chahrazed
authors.initials: C
authors.lastname: El Hamel
authors.forename: Delphine
authors.initials: D
authors.lastname: Haouzi
authors.forename: Sabine
authors.initials: S
authors.lastname: Druillenec
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Belzacq
authors.forename: Catherine
authors.initials: C
authors.lastname: Brenner
authors.forename: Bernard
authors.initials: B
authors.lastname: Roques
authors.forename: Guido
authors.initials: G
authors.lastname: Kroemer
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D004594:Electrophysiology; D005434:Flow Cytometry; D006367:HeLa Cells; D022781:Hepatocytes; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects; D007473:Ion Channels / Q000378:metabolism; D019169:Jurkat Cells; D008081:Liposomes / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology*; D010539:Permeability / Q000187:drug effects; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism* / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D051381:Rats; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
chemical_list: C494826:BAX protein, human; C494811:BCL2L1 protein, human; C494827:Bax protein, mouse; C494828:Bax protein, rat; C494812:Bcl2l1 protein, mouse; C494813:Bcl2l1 protein, rat; D007473:Ion Channels; D008081:Liposomes; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein