scholarly journals Enterovirus 71 2B Induces Cell Apoptosis by Directly Inducing the Conformational Activation of the Proapoptotic Protein Bax

2016 ◽  
Vol 90 (21) ◽  
pp. 9862-9877 ◽  
Author(s):  
Haolong Cong ◽  
Ning Du ◽  
Yang Yang ◽  
Lei Song ◽  
Wenliang Zhang ◽  
...  
Keyword(s):  
Cell Apoptosis ◽  
Enterovirus 71 ◽  
Terminal Region ◽  
Ev71 Infection ◽  
Apoptotic Pathway ◽  
Hydrophobic Region ◽  
Mitochondrial Apoptotic Pathway ◽  
Proapoptotic Protein ◽  
2B Protein ◽  
Induced Apoptosis

ABSTRACTTo survive and replicate within a host, many viruses have evolved strategies that target crucial components within the apoptotic cascade, leading to either inhibition or induction of cell apoptosis. Enterovirus 71 (EV71) infections have been demonstrated to impact the mitochondrial apoptotic pathway and induce apoptosis in many cell lines. However, the detailed mechanism of EV71-induced apoptosis remains to be elucidated. In this study, we report that EV71 2B protein (2B) localized to the mitochondria and induced cell apoptosis by interacting directly with and activating the proapoptotic protein Bax. 2B recruited Bax to the mitochondria and induced Bax conformational activation. In addition, mitochondria isolated from 2B-expressing cells that were treated with a recombinant Bax showed increased Bax interaction and cytochromec(Cytc) release. Importantly, apoptosis in cells with either EV71 infection or 2B expression was dramatically reduced in Bax knockdown cells but not in Bak knockdown cells, suggesting that Bax played a pivotal role in EV71- or 2B-induced apoptosis. Further studies indicate that a hydrophobic region of 18 amino acids (aa) in the C-terminal region of 2B (aa 63 to 80) was responsible for the location of 2B in the mitochondria. A hydrophilic region of 14 aa in the N-terminal region of 2B was functional in Bax interaction and its subsequent activation. Moreover, overexpression of the antiapoptotic protein Bcl-XLabrogates 2B-induced release of Cytcand caspase activation. Therefore, this study provides direct evidence that EV71 2B induces cell apoptosis and impacts the mitochondrial apoptotic pathway by directly modulating the redistribution and activation of proapoptotic protein Bax.IMPORTANCEEV71 infections are usually accompanied by severe neurological complications. It has also been postulated that the induction of cell apoptosis resulting from tissue damage is a possible process of EV71-related pathogenesis. In this study, we report that EV71 2B protein (2B) localized to the mitochondria and induced cell apoptosis by interacting directly with and activating the proapoptotic protein Bax. This study provides evidence that EV71 induces cell apoptosis by modulating Bax activation and reveals important clues regarding the mechanism of Cytcrelease and mitochondrial permeabilization during EV71 infection.

scholarly journals Calcium flux and calpain-mediated activation of the apoptosis-inducing factor contribute to enterovirus 71-induced apoptosis

2013 ◽  
Vol 94 (7) ◽  
pp. 1477-1485 ◽  
Author(s):  
Jia-Rong Lu ◽  
Wen-Wen Lu ◽  
Jian-Zhong Lai ◽  
Fu-Lian Tsai ◽  
Szu-Hsien Wu ◽  
...  
Keyword(s):  
Enterovirus 71 ◽  
Confocal Imaging ◽  
Ev71 Infection ◽  
Calcium Flux ◽  
Apoptotic Pathway ◽  
Fractionation Analysis ◽  
Infected Cells ◽  
Induced Apoptosis ◽  
Apoptosis Inducing Factor ◽  
The Impact

Enterovirus 71 (EV71) is a causative agent of an array of childhood diseases with severe neurological manifestations implicated. EV71 infection is known to induce caspase-dependent apoptosis in cell cultures and animal models. However, whether an alternative apoptotic pathway independent of caspase activation can be triggered by EV71 infection has not been explored. In this study, we showed that calcium (Ca2+)-activated calpains are capable of mediating caspase-independent pathway activation during EV71-induced apoptosis in HeLa cells. Results from subcellular fractionation analysis and confocal imaging indicated that during EV71 infection, apoptosis-inducing factor (AIF), a primary mediator of the caspase-independent pathway, became truncated and translocated from the mitochondrion to nucleus. This was accompanied by the release of cytochrome c, and sharply decreased mitochondrial membrane potential. AIF knockdown data indicated significant protection against apoptotic cell death, with greater protection provided by the addition of a pan-caspase inhibitor. The Ca2+-dependent, calpain isoforms 1 and 2, but not cathepsins, were proven crucial for the altered AIF behaviour as studied by the pharmacological inhibitor and the knockdown approaches. We then analysed Ca2+ dynamics in the infected cells and found elevated levels of mitochondrial Ca2+. Treatment with ruthenium red, a mitochondrial Ca2+ influx inhibitor, significantly blocked calpain activations and AIF cleavage. Our conclusion was that calpain activation via Ca2+ flux plays an essential role in eliciting an AIF-mediated, caspase-independent apoptotic pathway in EV71-infected cells. These findings should be useful for understanding the virus-induced cytopathology and the impact of Ca2+ homeostasis on EV71 infection.

scholarly journals Zika virus infection induced apoptosis by modulating the recruitment and activation of pro-apoptotic protein Bax

2021 ◽  
Author(s):  
Xiaodong Han ◽  
Jiuqiang Wang ◽  
Yang Yang ◽  
Shuxiang Qu ◽  
Fang Wan ◽  
...  
Keyword(s):  
Zika Virus ◽  
Cell Apoptosis ◽  
Zikv Infection ◽  
Apoptotic Pathway ◽  
Subsequent Formation ◽  
Mitochondrial Apoptotic Pathway ◽  
Detailed Mechanism ◽  
Apoptotic Protein ◽  
Cyt C ◽  
Induced Apoptosis

Zika virus (ZIKV) infection is associated with microcephaly in newborns and serious neurological complications in adults. Apoptosis of neural progenitor cells induced by ZIKV infection is believed to be a main reason for ZIKV infection-related microcephaly. However, the detailed mechanism of ZIKV infection-induced apoptosis remains to be elucidated. In this report, ZIKV infection induced the conformational activation of the pro-apoptotic protein Bax, with subsequent formation of oligomers of Bax in the mitochondria. Cell apoptosis was reduced significantly in SY5Y cells subjected to Bax knockdown. Additionally, while decreasing Bax expression inhibited the release of Cyt c from the mitochondria and reduced the rate of loss of mitochondrial membrane potential induced by ZIKV infection, silencing Bak, caspase-8, and/or caspase-10 expression did not. Mitochondria isolated from the untreated ZIKV-infected cells displayed Bax-binding ability and the subsequent release of Cyt c. This study also indicated that the NS4B protein of ZIKV recruited Bax to the mitochondria and induced Bax conformational activation. The overexpressed NS4B was localized to the mitochondria and induced cell apoptosis by activating the pro-apoptotic protein Bax. All the above results indicated that ZIKV infection directly impacted the mitochondrial apoptotic pathway by modulating the recruitment and activation of Bax. Importance: Since the large outbreaks that occurred in the Pacific Islands and Latin America in 2013, Zika virus has been confirmed a neuroteratogenic pathogen and causative agent of microcephaly and other developmental anomalies of the central nervous system in children born to infected mothers. As the widespread apoptosis throughout the whole brain, studies in animal models have reinforced the link between microcephaly caused by ZIKV infection and NPC apoptosis. Currently, the detailed mechanism of ZIKV infection-induced apoptosis still remains to be elucidated. Here, we firstly demonstrate that ZIKV infection activated the classic signs of mitochondrial apoptotic pathway by modulating the recruitment and activation of Bax. ZIKV NS4B represents a novel viral apoptotic protein that can modulate the recruitment and activation of Bax and trigger the apoptotic program. This is a new insight into understanding the interplay between apoptosis and ZIKV infection.

MicroRNA-15b enhances hypoxia/reoxygenation-induced apoptosis of cardiomyocytes via a mitochondrial apoptotic pathway

APOPTOSIS ◽  
2013 ◽  
Vol 19 (1) ◽  
pp. 19-29 ◽  
Author(s):  
Lifeng Liu ◽  
Guoming Zhang ◽  
Zhuo Liang ◽  
Xiuhua Liu ◽  
Tiande Li ◽  
...  
Keyword(s):  
Apoptotic Pathway ◽  
Mitochondrial Apoptotic Pathway ◽  
Induced Apoptosis ◽  
Hypoxia Reoxygenation

scholarly journals Enterovirus 71 Represses Interleukin Enhancer-Binding Factor 2 Production and Nucleus Translocation to Antagonize ILF2 Antiviral Effects

Viruses ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 22
Author(s):  
Jing Jin ◽  
Wenbiao Wang ◽  
Sha Ai ◽  
Weiyong Liu ◽  
Yu Song ◽  
...  
Keyword(s):  
Nonstructural Protein ◽  
Enterovirus 71 ◽  
Ev71 Infection ◽  
Health It ◽  
Antiviral Effects ◽  
Distinct Mechanism ◽  
Binding Factor ◽  
2B Protein ◽  
Rd Cells ◽  
Hand Foot Mouth Disease

Enterovirus 71 (EV71) infection causes hand-foot-mouth disease (HFMD), meningoencephalitis, neonatal sepsis, and even fatal encephalitis in children, thereby presenting a serious risk to public health. It is important to determine the mechanisms underlying the regulation of EV71 infection. In this study, we initially show that the interleukin enhancer-binding factor 2 (ILF2) reduces EV71 50% tissue culture infective dose (TCID50) and attenuates EV71 plaque-formation unit (PFU), thereby repressing EV71 infection. Microarray data analyses show that ILF2 mRNA is reduced upon EV71 infection. Cellular studies indicate that EV71 infection represses ILF2 mRNA expression and protein production in human leukemic monocytes (THP-1) -differentiated macrophages and human rhabdomyosarcoma (RD) cells. In addition, EV71 nonstructural protein 2B interacts with ILF2 in human embryonic kidney (HEK293T) cells. Interestingly, in the presence of EV71 2B, ILF2 is translocated from the nucleus to the cytoplasm, and it colocalizes with 2B in the cytoplasm. Therefore, we present a distinct mechanism by which EV71 antagonizes ILF2-mediated antiviral effects by inhibiting ILF2 expression and promoting ILF2 translocation from the nucleus to the cytoplasm through its 2B protein.

Ghrelin ameliorates A549 cell apoptosis caused by paraquat via p38-MAPK regulated mitochondrial apoptotic pathway

Toxicology ◽  
2019 ◽  
Vol 426 ◽  
pp. 152267 ◽  
Author(s):  
Shuqing Cui ◽  
Qing Nian ◽  
Gang Chen ◽  
Xingyong Wang ◽  
Jinying Zhang ◽  
...  
Keyword(s):  
P38 Mapk ◽  
A549 Cell ◽  
Cell Apoptosis ◽  
Apoptotic Pathway ◽  
Mitochondrial Apoptotic Pathway

scholarly journals CRISPR/Cas9 Knockout of Bak Mediates Bax Translocation to Mitochondria in response to TNFα/CHX-induced Apoptosis

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Jingtian Zhang ◽  
Han Niu ◽  
Zhizhuang Joe Zhao ◽  
Xueqi Fu ◽  
Yuxiang Wang ◽  
...  
Keyword(s):  
Cell Line ◽  
Parp Cleavage ◽  
Caspase 8 ◽  
Caspase Activation ◽  
Apoptotic Pathway ◽  
Mitochondrial Apoptotic Pathway ◽  
Apoptotic Protein ◽  
Induced Apoptosis

TNFα/CHX-induced apoptosis is dependent on caspase-8 activation and regulated by Bcl-2. However, the specific participants and precise mechanisms underlying this apoptotic pathway are poorly understood. The proapoptotic proteins Bak and Bax—members of the Bcl-2 family—are essential for the functioning of the mitochondrial apoptotic pathway. In this study, we used the CRISPR/Cas9 system to knockout Bak in the human SH-SY5Y cell line and determined the effects of this knockout on TNFα/CHX-induced apoptosis. Our data showed that overexpression of Bcl-2 dramatically prevented TNFα/CHX-induced apoptosis, and then pro-apoptotic protein Bak was downregulated and became more resistant to TNFα/CHX-induced apoptosis, because both TNFα/CHX-induced PARP cleavage and caspase activation were blocked in BAK−/− cells or using specific siRNA, whereas Bax was dispensable in TNFα/CHX-induced apoptosis, as evidenced using specific siRNA. Bax translocated from the cytosol into the mitochondria in response to TNFα/CHX, and CRISPR/Cas9 knockout of Bak significantly decreased this translocation. These results indicate that TNFα/CHX-induced apoptosis does not occur in Bak−/− cells, suggesting that TNFα/CHX-induced apoptosis is Bak-dependent but Bax-independent.

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