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Protochlamydia induces apoptosis of human HEp-2 cells through mitochondrial dysfunction mediated by chlamydial protease-like activity factor.

Matsuo J, Nakamura S, Ito A, Yamazaki T, Ishida K, Hayashi Y, Yoshida M, Takahashi K, Sekizuka T, Takeuchi F, Kuroda M, Nagai H, Hayashida K, Sugimoto C, Yamaguchi H - PLoS ONE (2013)

Bottom Line: A decrease of the mitochondrial membrane potential was also confirmed.Interestingly, Yersinia type III inhibitors (ME0052, ME0053, and ME0054) did not have any effect on the apoptosis.Thus, our results indicate that after entry, Protochlamydia-secreted CPAF induces mitochondrial dysfunction with a decrease of the membrane potential, followed by caspase-9, caspase-3 and PARP cleavages for apoptosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan.

ABSTRACT
Obligate amoebal endosymbiotic bacterium Protochlamydia with ancestral pathogenic chlamydial features evolved to survive within protist hosts, such as Acanthamoba, 0.7-1.4 billion years ago, but not within vertebrates including humans. This observation raises the possibility that interactions between Protochlamydia and human cells may result in a novel cytopathic effect, leading to new insights into host-parasite relationships. Previously, we reported that Protochlamydia induces apoptosis of the immortalized human cell line, HEp-2. In this study, we attempted to elucidate the molecular mechanism underlying this apoptosis. We first confirmed that, upon stimulation with the bacteria, poly (ADP-ribose) polymerase (PARP) was cleaved at an early stage in HEp-2 cells, which was dependent on the amount of bacteria. A pan-caspase inhibitor and both caspase-3 and -9 inhibitors similarly inhibited the apoptosis of HEp-2 cells. A decrease of the mitochondrial membrane potential was also confirmed. Furthermore, lactacystin, an inhibitor of chlamydial protease-like activity factor (CPAF), blocked the apoptosis. Cytochalasin D also inhibited the apoptosis, which was dependent on the drug concentration, indicating that bacterial entry into cells was required to induce apoptosis. Interestingly, Yersinia type III inhibitors (ME0052, ME0053, and ME0054) did not have any effect on the apoptosis. We also confirmed that the Protochlamydia used in this study possessed a homologue of the cpaf gene and that two critical residues, histidine-101 and serine-499 of C. trachomatis CPAF in the active center, were conserved. Thus, our results indicate that after entry, Protochlamydia-secreted CPAF induces mitochondrial dysfunction with a decrease of the membrane potential, followed by caspase-9, caspase-3 and PARP cleavages for apoptosis. More interestingly, because C. trachomatis infection can block the apoptosis, our finding implies unique features of CPAF between pathogenic and primitive chlamydiae.

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Hypothetical pathway of Protochlamydia-induced apoptosis of immortalized human HEp-2 cells.
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pone-0056005-g007: Hypothetical pathway of Protochlamydia-induced apoptosis of immortalized human HEp-2 cells.

Mentions: In conclusion, we elucidated the molecular mechanism of HEp-2 cell apoptosis induced by Protochlamydia R18, showing that after entry, Protochlamydia-secreted CPAF induces mitochondrial dysfunction with a decrease of the membrane potential, followed by caspase-9, caspase-3 and PARP cleavages for apoptosis (a hypothetical scenario, Figure 7). The finding suggests a possible evolutionary path in which pathogenic chlamydiae may begin to eliminate the strong cytopathic effect of ancestral chlamydia on mammalian cells, and a serine-protease enzyme, CPAF, may be a key molecule that determines the survival of host cell.


Protochlamydia induces apoptosis of human HEp-2 cells through mitochondrial dysfunction mediated by chlamydial protease-like activity factor.

Matsuo J, Nakamura S, Ito A, Yamazaki T, Ishida K, Hayashi Y, Yoshida M, Takahashi K, Sekizuka T, Takeuchi F, Kuroda M, Nagai H, Hayashida K, Sugimoto C, Yamaguchi H - PLoS ONE (2013)

Hypothetical pathway of Protochlamydia-induced apoptosis of immortalized human HEp-2 cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3569409&req=5

pone-0056005-g007: Hypothetical pathway of Protochlamydia-induced apoptosis of immortalized human HEp-2 cells.
Mentions: In conclusion, we elucidated the molecular mechanism of HEp-2 cell apoptosis induced by Protochlamydia R18, showing that after entry, Protochlamydia-secreted CPAF induces mitochondrial dysfunction with a decrease of the membrane potential, followed by caspase-9, caspase-3 and PARP cleavages for apoptosis (a hypothetical scenario, Figure 7). The finding suggests a possible evolutionary path in which pathogenic chlamydiae may begin to eliminate the strong cytopathic effect of ancestral chlamydia on mammalian cells, and a serine-protease enzyme, CPAF, may be a key molecule that determines the survival of host cell.

Bottom Line: A decrease of the mitochondrial membrane potential was also confirmed.Interestingly, Yersinia type III inhibitors (ME0052, ME0053, and ME0054) did not have any effect on the apoptosis.Thus, our results indicate that after entry, Protochlamydia-secreted CPAF induces mitochondrial dysfunction with a decrease of the membrane potential, followed by caspase-9, caspase-3 and PARP cleavages for apoptosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan.

ABSTRACT
Obligate amoebal endosymbiotic bacterium Protochlamydia with ancestral pathogenic chlamydial features evolved to survive within protist hosts, such as Acanthamoba, 0.7-1.4 billion years ago, but not within vertebrates including humans. This observation raises the possibility that interactions between Protochlamydia and human cells may result in a novel cytopathic effect, leading to new insights into host-parasite relationships. Previously, we reported that Protochlamydia induces apoptosis of the immortalized human cell line, HEp-2. In this study, we attempted to elucidate the molecular mechanism underlying this apoptosis. We first confirmed that, upon stimulation with the bacteria, poly (ADP-ribose) polymerase (PARP) was cleaved at an early stage in HEp-2 cells, which was dependent on the amount of bacteria. A pan-caspase inhibitor and both caspase-3 and -9 inhibitors similarly inhibited the apoptosis of HEp-2 cells. A decrease of the mitochondrial membrane potential was also confirmed. Furthermore, lactacystin, an inhibitor of chlamydial protease-like activity factor (CPAF), blocked the apoptosis. Cytochalasin D also inhibited the apoptosis, which was dependent on the drug concentration, indicating that bacterial entry into cells was required to induce apoptosis. Interestingly, Yersinia type III inhibitors (ME0052, ME0053, and ME0054) did not have any effect on the apoptosis. We also confirmed that the Protochlamydia used in this study possessed a homologue of the cpaf gene and that two critical residues, histidine-101 and serine-499 of C. trachomatis CPAF in the active center, were conserved. Thus, our results indicate that after entry, Protochlamydia-secreted CPAF induces mitochondrial dysfunction with a decrease of the membrane potential, followed by caspase-9, caspase-3 and PARP cleavages for apoptosis. More interestingly, because C. trachomatis infection can block the apoptosis, our finding implies unique features of CPAF between pathogenic and primitive chlamydiae.

Show MeSH
Related in: MedlinePlus