RESUMEN
Lethal small molecules are useful probes to discover and characterize novel cell death pathways and biochemical mechanisms. Here we report that the synthetic oxime-containing small molecule caspase-independent lethal 56 (CIL56) induces an unconventional form of nonapoptotic cell death distinct from necroptosis, ferroptosis, and other pathways. CIL56-induced cell death requires a catalytically active protein S-acyltransferase complex comprising the enzyme ZDHHC5 and an accessory subunit GOLGA7. The ZDHHC5-GOLGA7 complex is mutually stabilizing and localizes to the plasma membrane. CIL56 inhibits anterograde protein transport from the Golgi apparatus, which may be lethal in the context of ongoing ZDHHC5-GOLGA7 complex-dependent retrograde protein trafficking from the plasma membrane to internal sites. Other oxime-containing small molecules, structurally distinct from CIL56, may trigger cell death through the same pathway. These results define an unconventional form of nonapoptotic cell death regulated by protein S-acylation.
Asunto(s)
Aciltransferasas/metabolismo , Muerte Celular , Proteínas de la Matriz de Golgi/metabolismo , Acilación , Aciltransferasas/química , Aciltransferasas/genética , Animales , Muerte Celular/efectos de los fármacos , Línea Celular , Membrana Celular/metabolismo , Compuestos de Anillos Fusionados/química , Compuestos de Anillos Fusionados/farmacología , Aparato de Golgi/efectos de los fármacos , Aparato de Golgi/metabolismo , Aparato de Golgi/ultraestructura , Proteínas de la Matriz de Golgi/química , Proteínas de la Matriz de Golgi/genética , Humanos , Ratones , Oximas/química , Oximas/farmacología , Proteína S/metabolismo , Transporte de Proteínas/efectos de los fármacosRESUMEN
The initiation and execution of cell death can be regulated by various lipids. How the levels of environmental (exogenous) lipids impact cell death sensitivity is not well understood. We find that exogenous monounsaturated fatty acids (MUFAs) potently inhibit the non-apoptotic, iron-dependent, oxidative cell death process of ferroptosis. This protective effect is associated with the suppression of lipid reactive oxygen species (ROS) accumulation at the plasma membrane and decreased levels of phospholipids containing oxidizable polyunsaturated fatty acids. Treatment with exogenous MUFAs reduces the sensitivity of plasma membrane lipids to oxidation over several hours. This effect requires MUFA activation by acyl-coenzyme A synthetase long-chain family member 3 (ACSL3) and is independent of lipid droplet formation. Exogenous MUFAs also protect cells from apoptotic lipotoxicity caused by the accumulation of saturated fatty acids, but in an ACSL3-independent manner. Our work demonstrates that ACSL3-dependent MUFA activation promotes a ferroptosis-resistant cell state.
Asunto(s)
Ácidos Grasos Monoinsaturados/farmacología , Ferroptosis/efectos de los fármacos , Lípidos/química , Animales , Ácido Araquidónico/química , Ácido Araquidónico/metabolismo , Ácido Araquidónico/farmacología , Línea Celular , Membrana Celular/química , Membrana Celular/metabolismo , Coenzima A Ligasas/metabolismo , Ácidos Grasos Monoinsaturados/química , Ácidos Grasos Monoinsaturados/metabolismo , Gotas Lipídicas/química , Gotas Lipídicas/metabolismo , Ratones , Oxidación-Reducción , Fosfolípido Hidroperóxido Glutatión Peroxidasa/genética , Fosfolípido Hidroperóxido Glutatión Peroxidasa/metabolismo , Especies Reactivas de Oxígeno/química , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Protein S-palmitoylation is a reversible post-translational modification that alters the localization, stability, and function of hundreds of proteins in the cell. S-palmitoylation is essential for the function of both oncogenes (e.g., NRAS and EGFR) and tumor suppressors (e.g., SCRIB, melanocortin 1 receptor). In mammalian cells, the thioesterification of palmitate to internal cysteine residues is catalyzed by 23 Asp-His-His-Cys (DHHC)-family palmitoyl S-acyltransferases while the removal of palmitate is catalyzed by serine hydrolases, including acyl-protein thioesterases (APTs). These enzymes modulate the function of important oncogenes and tumor suppressors and often display altered expression patterns in cancer. Targeting S-palmitoylation or the enzymes responsible for palmitoylation dynamics may therefore represent a candidate therapeutic strategy for certain cancers.
Asunto(s)
Lipoilación/genética , Proteínas de Neoplasias/metabolismo , Neoplasias/genética , Procesamiento Proteico-Postraduccional/genética , Aciltransferasas/genética , Humanos , Proteínas de Neoplasias/genética , Neoplasias/metabolismo , Proteolisis , Especificidad por SustratoRESUMEN
BACKGROUND: Despite detailed in vivo knowledge of glycolytic enolases and many bacterial non-enolase members of the superfamily, little is known about the in vivo function of vertebrate non-enolase enolase superfamily members (ENOSF1s). Results of previous studies suggest involvement of the ß splice form of ENOSF1 in breast and colon cancers. This study used the zebrafish (Danio rerio) as a vertebrate model of ENOSF1ß function. RESULTS: Whole mount in situ hybridization (WISH) showed that zebrafish ENOSF1ß (enosf1b) is zygotic and expressed ubiquitously through the first 24 hours post fertilization (hpf). After 24 hpf, enosf1b expression is restricted to the notochord. Embryos injected with enosf1b-EGFP mRNA grew slower than EGFP mRNA-injected embryos but caught up to the EGFP-injected embryos by 48 hpf. Embryos injected with ATG or exon 10 enosf1b mRNA-targeting morpholinos had kinked notochords, shortened anterior-posterior axes, and circulatory edema. WISH for ntl or pax2a expression showed that embryos injected with either morpholino have deformed notochord and pronephros. TUNEL staining revealed increased apoptosis in the peri-notochord region. CONCLUSIONS: This study is the first report of ENOSF1 function in a vertebrate and shows that ENOSF1 is required for embryonic development. Increased apoptosis following enosf1b knockdown suggests a potential survival advantage for increased ENOSF1ß expression in human cancers.
