title: Distinctive roles of PHAP proteins and prothymosin-alpha in a death regulatory pathway.
abstract: A small molecule, alpha-(trichloromethyl)-4-pyridineethanol (PETCM), was identified by high-throughput screening as an activator of caspase-3 in extracts of a panel of cancer cells. PETCM was used in combination with biochemical fractionation to identify a pathway that regulates mitochondria-initiated caspase activation. This pathway consists of tumor suppressor putative HLA-DR-associated proteins (PHAP) and oncoprotein prothymosin-alpha (ProT). PHAP proteins promoted caspase-9 activation after apoptosome formation, whereas ProT negatively regulated caspase-9 activation by inhibiting apoptosome formation. PETCM relieved ProT inhibition and allowed apoptosome formation at a physiological concentration of deoxyadenosine triphosphate. Elimination of ProT expression by RNA interference sensitized cells to ultraviolet irradiation-induced apoptosis and negated the requirement of PETCM for caspase activation. Thus, this chemical-biological combinatory approach has revealed the regulatory roles of oncoprotein ProT and tumor suppressor PHAP in apoptosis.
authors.affiliation: Howard Hughes Medical Institute, Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
authors.forename: Xuejun
authors.initials: X
authors.lastname: Jiang
authors.forename: Hyun-Eui
authors.initials: HE
authors.lastname: Kim
authors.forename: Hongjun
authors.initials: H
authors.lastname: Shu
authors.forename: Yingming
authors.initials: Y
authors.lastname: Zhao
authors.forename: Haichao
authors.initials: H
authors.lastname: Zhang
authors.forename: James
authors.initials: J
authors.lastname: Kofron
authors.forename: Jennifer
authors.initials: J
authors.lastname: Donnelly
authors.forename: Dave
authors.initials: D
authors.lastname: Burns
authors.forename: Shi-Chung
authors.initials: SC
authors.lastname: Ng
authors.forename: Saul
authors.initials: S
authors.lastname: Rosenberg
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis; D053477:Apoptotic Protease-Activating Factor 1; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002457:Cell Extracts; D003574:Cytochrome c Group / Q000378:metabolism; D003838:Deoxyadenine Nucleotides / Q000378:metabolism / Q000494:pharmacology; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D009479:Neuropeptides; D009687:Nuclear Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D011498:Protein Precursors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D011506:Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D011725:Pyridines / Q000737:chemistry / Q000494:pharmacology*; D034622:RNA Interference; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D015398:Signal Transduction; D013947:Thymosin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism
chemical_list: C087425:ANP32A protein, human; C490341:ANP32B protein, human; C506592:APAF1 protein, human; D053477:Apoptotic Protease-Activating Factor 1; D002457:Cell Extracts; D003574:Cytochrome c Group; D003838:Deoxyadenine Nucleotides; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D009687:Nuclear Proteins; D011498:Protein Precursors; D011506:Proteins; D011725:Pyridines; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D025521:Tumor Suppressor Proteins; C470638:alpha-(trichloromethyl)-4-pyridineethanol; C040782:prothymosin alpha; D013947:Thymosin; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; C026600:2'-deoxyadenosine triphosphate