RESUMEN
Endothelial monocyte-activating polypeptide II (EMAP II) is a proinflammatory cytokine and a chemoattractant for leukocytes. The mature cytokine is formed in apoptotic cells by cleavage of the precursor proEMAP II. Here we show that caspase-7 is capable of cleaving proEMAP II in vitro. A proEMAP II mutant, in which the ASTD cleavage site was changed to the sequence ASTA, was not processed by caspase-7. The caspase-7-mediated generation and release of mature EMAP II may provide a mechanism for leukocyte recruitment to sites of programmed cell death, and thus may link apoptosis to inflammation.
Asunto(s)
Caspasas/metabolismo , Citocinas , Proteínas de Neoplasias/metabolismo , Proteínas de Unión al ARN/metabolismo , Secuencia de Aminoácidos , Animales , Apoptosis , Secuencia de Bases , Sitios de Unión/genética , Caspasa 3 , Caspasa 7 , Caspasas/genética , Cartilla de ADN/genética , Técnicas In Vitro , Mediadores de Inflamación/metabolismo , Cinética , Ratones , Mutagénesis Sitio-Dirigida , Proteínas de Neoplasias/genética , Precursores de Proteínas/genética , Precursores de Proteínas/metabolismo , Procesamiento Proteico-Postraduccional , Proteínas de Unión al ARN/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Especificidad por SustratoRESUMEN
Endothelial monocyte-activating polypeptide II (EMAP II) is a proinflammatory cytokine and a chemoattractant for monocytes. We show here that, in the mouse embryo, EMAP II mRNA was most abundant at sites of tissue remodeling where many apoptotic cells could be detected by terminal deoxynucleotidyltransferase-mediated dUTP end labeling. Removal of dead cells is known to require macrophages, and these were found to colocalize with areas of EMAP II mRNA expression and programmed cell death. In cultured cells, post-translational processing of pro-EMAP II protein to the mature released EMAP II form (23 kDa) occurred coincidentally with apoptosis. Cleavage of pro-EMAP II could be abrogated in cultured cells by using a peptide-based inhibitor, which competes with the ASTD cleavage site of pro-EMAP II. Our results suggest that the coordinate program of cell death includes activation of a caspase-like activity that initiates the processing of a cytokine responsible for macrophage attraction to the sites of apoptosis.
