title: BH3-domain mimetic compound BH3I-2' induces rapid damage to the inner mitochondrial membrane prior to the cytochrome c release from mitochondria.
abstract: The Bcl-2 family proteins are major regulators of cell survival and death in human leukaemia. BH3-containing peptides induce apoptosis by binding to the hydrophobic pocket of the anti-apoptotic proteins, such as Bcl-2 or Bcl-XL. A small cell-permeable compound, BH3I-2' (3-iodo-5-chloro-N-[2-chloro-5-((4-chlorophenyl)sulphonyl)phenyl]-2-hydroxybenzamide), has been recently reported to have a function similar to Bak BH3 peptide. BH3I-2' induces apoptosis by disrupting interactions mediated by the BH3 domain, between pro-apoptotic and anti-apoptotic members of the Bcl-2 family. This study found that BH3I-2' induced cytochrome c release from the mitochondrial outer membrane in a Bax-dependent manner and that this correlated with the sensitivity of leukaemic cells to apoptosis. Moreover, it also induced rapid damage to the inner mitochondrial membrane, represented by a rapid collapse of mitochondrial membrane potential (DeltaPsim), prior to the cytochrome c release. This occurred both in whole cells and isolated mitochondria, and was not associated with the sensitivity of cells to BH3I-2'-induced apoptosis. Exogenous Bcl-2 or Bcl-XL neutralized BH3I-2'in vitro and diminished its effect on the inner mitochondrial membrane. Our results indicate that BH3I-2' not only induces cytochrome c release from the outer mitochondrial membrane but also damages the inner mitochondrial membrane, probably by interacting with Bcl-2 family proteins.
authors.affiliation: Department of Haematology, St Bartholomew's and the Royal London School of Medicine and Dentistry, London, UK.
authors.forename: Wan-Yu
authors.initials: WY
authors.lastname: Feng
authors.forename: Feng-Ting
authors.initials: FT
authors.lastname: Liu
authors.forename: Yasmeen
authors.initials: Y
authors.lastname: Patwari
authors.forename: Samir G
authors.initials: SG
authors.lastname: Agrawal
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Newland
authors.forename: Li
authors.initials: L
authors.lastname: Jia
mesh_terms: D000704:Analysis of Variance; D001549:Benzamides / Q000494:pharmacology; D040761:Biomimetic Materials; D002460:Cell Line; D002478:Cells, Cultured; D003574:Cytochrome c Group / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects*; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins
chemical_list: C474172:3-iodo-5-chloro-N-(2-chloro-5-((4-chlorophenyl)sulphonyl)phenyl)-2-hydroxybenzamide; C474007:Bax protein (53-86); D001549:Benzamides; D003574:Cytochrome c Group; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins