title: MAC inhibitors antagonize the pro-apoptotic effects of tBid and disassemble Bax / Bak oligomers.
abstract: Mitochondrial Apoptotic Channel inhibitors or iMACs are di-bromocarbazole derivatives with anti-apoptotic function which have been tested and validated in several mouse models of brain injury and neurodegeneration. Owing to the increased therapeutic potential of these compounds, we sought to expand our knowledge of their mechanism of action. We investigated the kinetics of MAC inhibition in mitochondria from wild type, Bak, and Bax knockout cell lines using patch clamp electrophysiology, fluorescence microscopy, ELISA, and semiquantitative western blot analyses. Our results show that iMACs work through at least two mechanisms: 1) by blocking relocation of the cytoplasmic Bax protein to mitochondria and 2) by disassembling Bax and Bak oligomers in the mitochondrial outer membrane. iMACs exert comparable effects on channel conductance of Bax or Bak and similarly affect cytochrome c release from Bax or Bak-containing mitochondria. Interestingly, wild type mitochondria were more susceptible to inhibition than the Bak or Bax knockouts. Western blot analysis showed that wild type mitochondria had lower steady state levels of Bak in the absence of apoptotic stimulation.
authors.affiliation: Baruch College and Graduate Center of City University of New York (CUNY), New York, NY, 10010, USA. pablo.peixoto@baruch.cuny.edu.|New York University College of Dentistry, New York, NY, 10010, USA. pablo.peixoto@baruch.cuny.edu.
authors.forename: Pablo M
authors.identifier: http://orcid.org/0000-0001-5953-6027
authors.initials: PM
authors.lastname: Peixoto
authors.affiliation: Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA.
authors.forename: Oscar
authors.initials: O
authors.lastname: Teijido
authors.affiliation: Baruch College and Graduate Center of City University of New York (CUNY), New York, NY, 10010, USA.
authors.forename: Oygul
authors.initials: O
authors.lastname: Mirzalieva
authors.affiliation: Department of Chemistry, California State University of Fresno, Fresno, CA, 93740, USA.
authors.forename: Laurent M
authors.initials: LM
authors.lastname: Dejean
authors.affiliation: New York University College of Dentistry, New York, NY, 10010, USA.
authors.forename: Evgeny V
authors.initials: EV
authors.lastname: Pavlov
authors.affiliation: Merck Serono, Geneva Research Center, Geneva, 1202, Switzerland.
authors.forename: Bruno
authors.initials: B
authors.lastname: Antonsson
authors.affiliation: New York University College of Dentistry, New York, NY, 10010, USA.
authors.forename: Kathleen W
authors.initials: KW
authors.lastname: Kinnally
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D051023:BH3 Interacting Domain Death Agonist Protein / Q000037:antagonists & inhibitors*; D002227:Carbazoles / Q000494:pharmacology*; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D055503:Protein Multimerization / Q000187:drug effects*; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
chemical_list: D051023:BH3 Interacting Domain Death Agonist Protein; C494773:Bak1 protein, mouse; D002227:Carbazoles; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c
keywords: Apoptosis; Bak; Bax; MAC inhibitors; MOMP; Patch clamp; tBid