title: Mcl-1 interacts with truncated Bid and inhibits its induction of cytochrome c release and its role in receptor-mediated apoptosis.
abstract: Engagement of death receptors such as tumor necrosis factor-R1 and Fas brings about the cleavage of cytosolic Bid to truncated Bid (tBid), which translocates to mitochondria to activate Bax/Bak, resulting in the release of cytochrome c. The mechanism underlying the activation, however, is not fully understood. Here, we have identified the anti-apoptotic Bcl-2 family member Mcl-1 as a potent tBid-binding partner. Site-directed mutagenesis reveals that the Bcl-2 homology (BH)3 domain of tBid is essential for binding to Mcl-1, whereas all three BH domains (BH1, BH2, and BH3) of Mcl-1 are required for interaction with tBid. In vitro studies using isolated mitochondria and recombinant proteins demonstrate that Mcl-1 strongly inhibits tBid-induced cytochrome c release. In addition to its ability to interact directly with Bax and Bak, tBid also binds Mcl-1 and displaces Bak from the Mcl-1-Bak complex. Importantly, overexpression of Mcl-1 confers resistance to the induction of apoptosis by both TRAIL and tumor necrosis factor-alpha in HeLa cells, whereas targeting Mcl-1 by RNA interference sensitizes HeLa cells to TRAIL-induced apoptosis. Therefore, our study demonstrates a novel regulation of tBid by Mcl-1 through protein-protein interaction in apoptotic signaling from death receptors to mitochondria.
authors.affiliation: Molecular Haematology and Cancer Biology Unit, Institute of Child Health and Great Ormond Street Hospital for Children, University College London, 30 Guilford Street, London WC1N 1EH, United Kingdom.
authors.forename: John G
authors.initials: JG
authors.lastname: Clohessy
authors.forename: Jianguo
authors.initials: J
authors.lastname: Zhuang
authors.forename: Jasper
authors.initials: J
authors.lastname: de Boer
authors.forename: Gabriel
authors.initials: G
authors.lastname: Gil-Gómez
authors.forename: Hugh J M
authors.initials: HJ
authors.lastname: Brady
mesh_terms: D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D051023:BH3 Interacting Domain Death Agonist Protein / Q000235:genetics / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D016297:Mutagenesis, Site-Directed; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020798:Two-Hybrid System Techniques; 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; D051023:BH3 Interacting Domain Death Agonist Protein; C579094:Mcl1 protein, mouse; D008562:Membrane Glycoproteins; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; C505654:Tnfsf10 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c