title: Involvement of caspase activation through release of cytochrome c from mitochondria in apoptotic cell death of macrophages infected with Actinobacillus actinomycetemcomitans.
abstract: We previously reported that infection with the periodontopathic bacterium Actinobacillus actinomycetemcomitans induced apoptosis in a mouse macrophage cell line J774.1. In the present study, we examined the involvement of cytochrome c and caspases in the induction of apoptosis in A. actinomycetemcomitans-infected J774.1 cells. Following infection, the expression levels of cytochrome c, and cleaved forms of caspase-3 and caspase-9 in the cells were examined using immunoblot analysis. Cytochrome c was released from mitochondria into the cytoplasm after A. actinomycetemcomitans-infected J774.1 cells were cultured for 6 h, and caspase-3 and caspase-9 were found to be cleaved forms in the cells. Further, caspase-9 activity was markedly increased, and phosphorylated p53 was detected in the cells 30 h following infection. These results suggest that apoptosis in A. actinomycetemcomitans-infected J774.1 cells is regulated by the release of cytochrome c from mitochondria into cytoplasm and the subsequent activation of caspases through phosphorylation of p53.
authors.affiliation: Department of Oral Microbiology, Kyushu Dental College, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580, Japan.
authors.forename: Hironori
authors.initials: H
authors.lastname: Kasai
authors.forename: Kozo
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Takeyoshi
authors.initials: T
authors.lastname: Koseki
authors.forename: Makoto
authors.initials: M
authors.lastname: Yokota
authors.forename: Tatsuji
authors.initials: T
authors.lastname: Nishihara
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000472:pathogenicity*; D000818:Animals; D017209:Apoptosis; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism*; D004789:Enzyme Activation; D015151:Immunoblotting; D008264:Macrophages / Q000382:microbiology*; D051379:Mice; D010718:Phosphatidylserines / Q000378:metabolism; D010766:Phosphorylation; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D010718:Phosphatidylserines; D016159:Tumor Suppressor Protein p53; D045304:Cytochromes c; C505409:Casp3 protein, mouse; C506434:Casp9 protein, mouse; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases