RESUMEN
It has been previously shown that the exotoxin of the important fish pathogen Photobacterium damselae ssp. piscicida is a key pathogenicity factor and is responsible for the extensive systemic apoptosis of macrophages and neutrophils seen in acute fish photobacteriosis. The focus of the present study was to further characterize the AIP56-induced apoptosis of sea bass professional phagocytes by assessing the involvement of caspases, mitochondria and oxidative stress. The resulting data indicate that the apoptotic response in peritoneal macrophages and neutrophils treated ex vivo with AIP56 involves activation of caspase-8, -9 and -3, and mitochondria as shown by loss of mitochondrial membrane potential, release of cytochrome c and over-production of ROS. These results together with previous data from this laboratory suggest that both the extrinsic and intrinsic apoptotic pathways are involved in the AIP56-induced phagocyte apoptosis.
Asunto(s)
Apoptosis/efectos de los fármacos , Toxinas Bacterianas/toxicidad , Exotoxinas/toxicidad , Macrófagos Peritoneales/efectos de los fármacos , Neutrófilos/efectos de los fármacos , Photobacterium/metabolismo , Animales , Inhibidores de Caspasas , Caspasas/metabolismo , Células Cultivadas , Macrófagos Peritoneales/citología , Macrófagos Peritoneales/fisiología , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Neutrófilos/citología , Neutrófilos/fisiologíaRESUMEN
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMEN
In this work, the gene and cDNA of the sea bass CD8alpha have been isolated and characterized. The coding sequence has an ORF of 666 bp. It retains the Ig motif that interacts with MHC and the two cysteines responsible for an intra-chain disulfide bridge. The hinge region contains the two essential cysteines involved in dimerization. The transmembrane region is well conserved in all analysed sequences. Similar to other teleosts, the cytoplasmic region lacks the consensus p56(lck) motif common in higher vertebrates. Analysis of the expression pattern using RT-PCR shows the highest expression in the thymus. Like in the human gene, the sea bass CD8alpha genomic structure is organized into six exons, which roughly correspond to separate functional domains of the protein. Southern blotting shows that CD8alpha exists as a single copy gene. Together, these results support the concept that the basic structure of CD8alpha has been maintained through evolution.