alpha-(trichloromethyl)-4-pyridineethanol and 2--deoxyadenosine-triphosphate

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.

Topics: Amino Acid Sequence; Apoptosis; Apoptotic Protease-Activating Factor 1; Caspase 3; Caspase 9; Caspases; Cell Extracts; Cytochrome c Group; Deoxyadenine Nucleotides; Enzyme Activation; HeLa Cells; Humans; Intracellular Signaling Peptides and Proteins; Mitochondria; Molecular Sequence Data; Neuropeptides; Nuclear Proteins; Protein Precursors; Proteins; Pyridines; Recombinant Proteins; RNA Interference; RNA-Binding Proteins; Signal Transduction; Thymosin; Tumor Suppressor Proteins