title: Mitochondrial p53 activates Bak and causes disruption of a Bak-Mcl1 complex.
abstract: The tumour suppressor activity of the p53 protein has been explained by its ability to induce apoptosis in response to a variety of cellular stresses. Thus, understanding the mechanism by which p53 functions in the execution of cell death pathways is of considerable importance in cancer biology. Recent studies have indicated that p53 has a direct signalling role at mitochondria in the induction of apoptosis, although the mechanisms involved are not completely understood. Here we show that, after cell stress, p53 interacts with the pro-apoptotic mitochondrial membrane protein Bak. Interaction of p53 with Bak causes oligomerization of Bak and release of cytochrome c from mitochondria. Notably, we show that formation of the p53-Bak complex coincides with loss of an interaction between Bak and the anti-apoptotic Bcl2-family member Mcl1. These results are consistent with a model in which p53 and Mcl1 have opposing effects on mitochondrial apoptosis by interacting with, and modulating the activity of, the death effector Bak.
authors.affiliation: Department of Genetics, University of Pennsylvania School of Medicine, 422 Curie Boulevard, Philadelphia, PA 19104, USA.
authors.forename: J I-Ju
authors.initials: JI
authors.lastname: Leu
authors.forename: Patrick
authors.initials: P
authors.lastname: Dumont
authors.forename: Michael
authors.initials: M
authors.lastname: Hafey
authors.forename: Maureen E
authors.initials: ME
authors.lastname: Murphy
authors.forename: Donna L
authors.initials: DL
authors.lastname: George
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000378:metabolism; D006801:Humans; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D050998:bcl-2 Homologous Antagonist-Killer Protein
chemical_list: C494772:BAK1 protein, human; D046911:Macromolecular Substances; D008565:Membrane Proteins; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins; D016159:Tumor Suppressor Protein p53; D050998:bcl-2 Homologous Antagonist-Killer Protein; D045304:Cytochromes c