title: Elimination of Mcl-1 is required for the initiation of apoptosis following ultraviolet irradiation.
abstract: Ultraviolet (UV) irradiation of HeLa cells triggers an apoptotic response mediated by mitochondria. Biochemical analysis of this response revealed that the elimination of cytosolic inhibitors is required for mitochondrial release of cytochrome c and subsequent caspase activation. These inhibitors were found to be Mcl-1 and Bcl-xL, two antiapoptotic members of the Bcl-2 family. Following UV treatment, Mcl-1 protein synthesis is blocked, the existing pool of Mcl-1 protein is rapidly degraded by the proteasome, and cytosolic Bcl-xL translocates to the mitochondria. These events are sequential; the elimination of Mcl-1 is required for the translocation of Bcl-xL. The disappearance of Mcl-1 is also required for other mitochondrial apoptotic events including Bax translocation, cytochrome c release, and caspase activation.
authors.affiliation: Howard Hughes Medical Institute & Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA.
authors.forename: Deepak
authors.initials: D
authors.lastname: Nijhawan
authors.forename: Min
authors.initials: M
authors.lastname: Fang
authors.forename: Elie
authors.initials: E
authors.lastname: Traer
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhong
authors.forename: Wenhua
authors.initials: W
authors.lastname: Gao
authors.forename: Fenghe
authors.initials: F
authors.lastname: Du
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Wang
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology* / Q000528:radiation effects; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism / Q000528:radiation effects; D003600:Cytosol / Q000378:metabolism; D006367:HeLa Cells / Q000528:radiation effects; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism / Q000528:radiation effects; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D021381:Protein Transport / Q000528:radiation effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D015398:Signal Transduction; D014466:Ultraviolet Rays / Q000009:adverse effects*; D051020:bcl-X Protein
chemical_list: D000590:Amino Acid Chloromethyl Ketones; C494811:BCL2L1 protein, human; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D003574:Cytochrome c Group; D007976:Leupeptins; D009097:Multienzyme Complexes; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D020169:Caspases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde