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.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Apoptosis*
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Apoptotic Protease-Activating Factor 1
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Caspase 3
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Caspase 9
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Caspases / metabolism
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Cell Extracts
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Cytochrome c Group / metabolism
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Deoxyadenine Nucleotides / metabolism
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Deoxyadenine Nucleotides / pharmacology
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Enzyme Activation
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HeLa Cells
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Humans
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Intracellular Signaling Peptides and Proteins
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Mitochondria / metabolism
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Molecular Sequence Data
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Neuropeptides*
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Nuclear Proteins / chemistry
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Nuclear Proteins / isolation & purification
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Nuclear Proteins / metabolism*
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Nuclear Proteins / pharmacology
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Protein Precursors / chemistry
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Protein Precursors / isolation & purification
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Protein Precursors / metabolism*
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Protein Precursors / pharmacology
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Proteins / chemistry
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Proteins / isolation & purification
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Proteins / metabolism*
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Proteins / pharmacology
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Pyridines / chemistry
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Pyridines / pharmacology*
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RNA Interference
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RNA-Binding Proteins
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Recombinant Proteins / metabolism
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Recombinant Proteins / pharmacology
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Signal Transduction
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Thymosin / analogs & derivatives*
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Thymosin / chemistry
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Thymosin / isolation & purification
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Thymosin / metabolism*
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Thymosin / pharmacology
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Tumor Suppressor Proteins / chemistry
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Tumor Suppressor Proteins / isolation & purification
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Tumor Suppressor Proteins / metabolism
Substances
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ANP32A protein, human
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ANP32B protein, human
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APAF1 protein, human
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Apoptotic Protease-Activating Factor 1
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Cell Extracts
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Cytochrome c Group
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Deoxyadenine Nucleotides
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Intracellular Signaling Peptides and Proteins
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Neuropeptides
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Nuclear Proteins
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Protein Precursors
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Proteins
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Pyridines
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RNA-Binding Proteins
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Recombinant Proteins
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Tumor Suppressor Proteins
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alpha-(trichloromethyl)-4-pyridineethanol
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prothymosin alpha
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Thymosin
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CASP3 protein, human
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CASP9 protein, human
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Caspase 3
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Caspase 9
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Caspases
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2'-deoxyadenosine triphosphate