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TNF-alpha mediates eosinophil cationic protein-induced apoptosis in BEAS-2B cells.

Chang KC, Lo CW, Fan TC, Chang MD, Shu CW, Chang CH, Chung CT, Fang SL, Chao CC, Tsai JJ, Lai YK - BMC Cell Biol. (2010)

Bottom Line: Caspase-8-dependent apoptosis was demonstrated by cleavage of caspase-8 after recombinant ECP treatment, accompanied with elevated level of tumor necrosis factor alpha (TNF-alpha).Moreover, ECP-induced apoptosis was effectively inhibited in the presence of neutralizing anti-TNF-alpha antibody.In conclusion, our results have demonstrated that ECP increased TNF-alpha production in BEAS-2B cells and triggered apoptosis by caspase-8 activation through mitochondria-independent pathway.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Life Science, Institute of Biotechnology, National Tsing Hua University, Hsinchu 30013, Taiwan.

ABSTRACT

Background: Eosinophilic granulocytes are important for the human immune system. Many cationic proteins with cytotoxic activities, such as eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN), are released from activated eosinophils. ECP, with low RNase activity, is widely used as a biomarker for asthma. ECP inhibits cell viability and induces apoptosis to cells. However, the specific pathway underlying the mechanisms of ECP-induced cytotoxicity remains unclear. This study investigated ECP-induced apoptosis in bronchial epithelial BEAS-2B cells and elucidated the specific pathway during apoptosis.

Results: To address the mechanisms involved in ECP-induced apoptosis in human BEAS-2B cells, investigation was carried out using chromatin condensation, cleavage of poly (ADP-ribose) polymerase (PARP), sub-G1 distribution in cell cycle, annexin V labeling, and general or specific caspase inhibitors. Caspase-8-dependent apoptosis was demonstrated by cleavage of caspase-8 after recombinant ECP treatment, accompanied with elevated level of tumor necrosis factor alpha (TNF-alpha). Moreover, ECP-induced apoptosis was effectively inhibited in the presence of neutralizing anti-TNF-alpha antibody.

Conclusion: In conclusion, our results have demonstrated that ECP increased TNF-alpha production in BEAS-2B cells and triggered apoptosis by caspase-8 activation through mitochondria-independent pathway.

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Related in: MedlinePlus

Role of rECP in TNF-α apoptosis signaling. rECP increases BEAS-2B cells TNF-α production and release. The release of TNF-α binding to TNF receptor results in receptor internalization and activates caspase-8. Caspase-8-induced apoptosis can either trigger mitochondrial response or directly cause PARP activation by caspase-3. However, rECP-induced apoptosis shows no effects on mitochondrial responses. Accordingly, we suggest that rECP induces mitochondria-independent apoptosis.
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Figure 8: Role of rECP in TNF-α apoptosis signaling. rECP increases BEAS-2B cells TNF-α production and release. The release of TNF-α binding to TNF receptor results in receptor internalization and activates caspase-8. Caspase-8-induced apoptosis can either trigger mitochondrial response or directly cause PARP activation by caspase-3. However, rECP-induced apoptosis shows no effects on mitochondrial responses. Accordingly, we suggest that rECP induces mitochondria-independent apoptosis.

Mentions: TNF-α receptor activation triggered apoptosis can undergo either mitochondria-dependent pathway which is involved in tBid activation and triggers caspase-9 activation by releasing cytochrome c, or mitochondria-independent pathway [59]. In our study, caspase-9 inhibitor, MMP assays and cytochrome c release experiments all indicated that rECP did not induce mitochondrial response, hence the apoptosis underwent mitochondria-independent pathway. Previous study has reported that caspase-6 is able to activate caspase-8 and involved in mitochondrial response [60]. However, it was proved that ECP-induced apoptosis did not require mitochondrial response; hence we speculated that caspase-8 was activated by TNFR pathway instead of caspase-6. Taken together, Figure 8 presents that ECP induces apoptosis involved in TNF-α-related caspase-8 activation through mitochondria-independent pathway.


TNF-alpha mediates eosinophil cationic protein-induced apoptosis in BEAS-2B cells.

Chang KC, Lo CW, Fan TC, Chang MD, Shu CW, Chang CH, Chung CT, Fang SL, Chao CC, Tsai JJ, Lai YK - BMC Cell Biol. (2010)

Role of rECP in TNF-α apoptosis signaling. rECP increases BEAS-2B cells TNF-α production and release. The release of TNF-α binding to TNF receptor results in receptor internalization and activates caspase-8. Caspase-8-induced apoptosis can either trigger mitochondrial response or directly cause PARP activation by caspase-3. However, rECP-induced apoptosis shows no effects on mitochondrial responses. Accordingly, we suggest that rECP induces mitochondria-independent apoptosis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2819994&req=5

Figure 8: Role of rECP in TNF-α apoptosis signaling. rECP increases BEAS-2B cells TNF-α production and release. The release of TNF-α binding to TNF receptor results in receptor internalization and activates caspase-8. Caspase-8-induced apoptosis can either trigger mitochondrial response or directly cause PARP activation by caspase-3. However, rECP-induced apoptosis shows no effects on mitochondrial responses. Accordingly, we suggest that rECP induces mitochondria-independent apoptosis.
Mentions: TNF-α receptor activation triggered apoptosis can undergo either mitochondria-dependent pathway which is involved in tBid activation and triggers caspase-9 activation by releasing cytochrome c, or mitochondria-independent pathway [59]. In our study, caspase-9 inhibitor, MMP assays and cytochrome c release experiments all indicated that rECP did not induce mitochondrial response, hence the apoptosis underwent mitochondria-independent pathway. Previous study has reported that caspase-6 is able to activate caspase-8 and involved in mitochondrial response [60]. However, it was proved that ECP-induced apoptosis did not require mitochondrial response; hence we speculated that caspase-8 was activated by TNFR pathway instead of caspase-6. Taken together, Figure 8 presents that ECP induces apoptosis involved in TNF-α-related caspase-8 activation through mitochondria-independent pathway.

Bottom Line: Caspase-8-dependent apoptosis was demonstrated by cleavage of caspase-8 after recombinant ECP treatment, accompanied with elevated level of tumor necrosis factor alpha (TNF-alpha).Moreover, ECP-induced apoptosis was effectively inhibited in the presence of neutralizing anti-TNF-alpha antibody.In conclusion, our results have demonstrated that ECP increased TNF-alpha production in BEAS-2B cells and triggered apoptosis by caspase-8 activation through mitochondria-independent pathway.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Life Science, Institute of Biotechnology, National Tsing Hua University, Hsinchu 30013, Taiwan.

ABSTRACT

Background: Eosinophilic granulocytes are important for the human immune system. Many cationic proteins with cytotoxic activities, such as eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN), are released from activated eosinophils. ECP, with low RNase activity, is widely used as a biomarker for asthma. ECP inhibits cell viability and induces apoptosis to cells. However, the specific pathway underlying the mechanisms of ECP-induced cytotoxicity remains unclear. This study investigated ECP-induced apoptosis in bronchial epithelial BEAS-2B cells and elucidated the specific pathway during apoptosis.

Results: To address the mechanisms involved in ECP-induced apoptosis in human BEAS-2B cells, investigation was carried out using chromatin condensation, cleavage of poly (ADP-ribose) polymerase (PARP), sub-G1 distribution in cell cycle, annexin V labeling, and general or specific caspase inhibitors. Caspase-8-dependent apoptosis was demonstrated by cleavage of caspase-8 after recombinant ECP treatment, accompanied with elevated level of tumor necrosis factor alpha (TNF-alpha). Moreover, ECP-induced apoptosis was effectively inhibited in the presence of neutralizing anti-TNF-alpha antibody.

Conclusion: In conclusion, our results have demonstrated that ECP increased TNF-alpha production in BEAS-2B cells and triggered apoptosis by caspase-8 activation through mitochondria-independent pathway.

Show MeSH
Related in: MedlinePlus