scholarly journals SARS-CoV-2 Membrane Glycoprotein M Triggers Apoptosis With the Assistance of Nucleocapsid Protein N in Cells

Author(s):  
Yujie Ren ◽  
An Wang ◽  
Yuan Fang ◽  
Ting Shu ◽  
Di Wu ◽  
...  

The pandemic of COVID-19 by SARS-CoV-2 has become a global disaster. However, we still don’t know how specific SARS-CoV-2-encoded proteins contribute to viral pathogenicity. We found that SARS-CoV-2-encoded membrane glycoprotein M could induce caspase-dependent apoptosis via interacting with PDK1 and inhibiting the activation of PDK1-PKB/Akt signaling. Our investigation further revealed that SARS-CoV-2-encoded nucleocapsid protein N could specifically enhance the M-induced apoptosis via interacting with both M and PDK1, therefore strengthening M-mediated attenuation of PDK1-PKB/Akt interaction. Furthermore, when the M-N interaction was disrupted via certain rationally designed peptides, the PDK1-PKB/Akt signaling was restored, and the boosting activity of N on the M-triggered apoptosis was abolished. Overall, our findings uncovered a novel mechanism by which SARS-CoV-2-encoded M triggers apoptosis with the assistance of N, which expands our understanding of the two key proteins of SARS-CoV-2 and sheds light on the pathogenicity of this life-threatening virus.

Author(s):  
D. W. Fairbain ◽  
M.D. Standing ◽  
K.L. O'Neill

Apoptosis is a genetically defined response to physiological stimuli that results in cellular suicide. Features common to apoptotic cells include chromatin condensation, oligonucleosomal DNA fragmentation, membrane blebbing, nuclear destruction, and late loss of ability to exclude vital dyes. These characteristics contrast markedly from pathological necrosis, in which membrane integrity loss is demonstrated early, and other features of apoptosis, which allow a non-inflammatory removal of dead and dying cells, are absent. Using heat shock-induced apoptosis as a model for examining stress response in cells, we undertook to categorize a variety of human leukemias and lymphomas with regard to their response to heat shock. We were also interested in determining whether a common temporal order was followed in cells dying by apoptosis. In addition, based on our previous results, we investigated whether increasing heat load resulted in increased apoptosis, with particular interest in relatively resistant cell lines, or whether the mode of death changed from apoptosis to necrosis.


2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xu Gao ◽  
Jingya Dai ◽  
Guifang Li ◽  
Xinya Dai

Abstract Objective In this work, we investigated the effects of gambogic acid (GA) on lipopolysaccharide (LPS)-induced apoptosis and inflammation in a cell model of neonatal pneumonia. Method Human WI-38 cells were maintained in vitro and incubated with various concentrations of GA to examine WI-38 survival. GA-preincubated WI-38 cells were then treated with LPS to investigate the protective effects of GA on LPS-induced death, apoptosis and inflammation. Western blot assay was utilized to analyze the effect of GA on tropomyosin receptor kinase A (TrkA) signaling pathway in LPS-treated WI-38 cells. In addition, human AKT serine/threonine kinase 1 (Akt) gene was knocked down in WI-38 cells to further investigate the associated genetic mechanisms of GA in protecting LPS-induced inflammation and apoptosis. Results Pre-incubating WI-38 cells with low and medium concentrations GA protected LPS-induced cell death, apoptosis and inflammatory protein productions of IL-6 and MCP-1. Using western blot assay, it was demonstrated that GA promoted TrkA phosphorylation and Akt activation in LPS-treated WI-38 cells. Knocking down Akt gene in WI-38 cells showed that GA-associated protections against LPS-induced apoptosis and inflammation were significantly reduced. Conclusions GA protected LPS-induced apoptosis and inflammation, possibly through the activations of TrkA and Akt signaling pathway. This work may broaden our understanding on the molecular mechanisms of human neonatal pneumonia.


2021 ◽  
Author(s):  
Xiaoxia Yang ◽  
Mengxia Wang ◽  
Qian Zhou ◽  
Yanxian Bai ◽  
Jing Liu ◽  
...  

Abstract Lepidium meyenii (Maca) is an annual or biennial herb from South America that is a member of the genus Lepidium L. in the family Cruciferae. This herb has antioxidant, anti-apoptotic, and enhances autophagy functions and can prevent cell death, and protect neurons from ischemic damage. Macamide B, an effective active ingredient of maca, has a neuroprotective role in neonatal hypoxic-ischemic brain damage (HIBD), and the underlying mechanism of its neuroprotective effect is not yet known. The purpose of this study is to explore the impact of macamide B on HIBD-induced autophagy and apoptosis and its potential mechanism for neuroprotection. The modified Rice-Vannucci method was used to induce HIBD on 7-day-old (P7) macamide B and vehicle-pretreated pups. TTC staining was used to evaluate the cerebral infarct volume of pups, brain water content was measured to evaluate the neurological function of pups, neurobehavioral testing was used to assess functional recovery after HIBD, TUNEL and FJC staining was used to detect cell autophagy and apoptosis, and western blot analysis was used to detect the expression levels of the pro-survival signaling pathway phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) and autophagy and the apoptosis-related proteins. The results show that macamide B pretreatment can significantly decrease brain damage, improve the recovery of neural function after HIBD. At the same time, macamide B pretreatment can induce the activation of PI3K/AKT signaling pathway after HIBD, enhance autophagy, and reduce hypoxic-ischemic (HI)-induced apoptosis. In addition, 3-methyladenine (3-MA), an inhibitor of PI3K/AKT signaling pathway, significantly inhibits the increase in autophagy levels, aggravates HI-induced apoptosis, and reverses the neuroprotective effect of macamide B on HIBD. Our data indicate that macamide B pretreatment might regulate autophagy through PI3K/AKT signaling pathway, thereby reducing HIBD-induced apoptosis and exerting neuroprotective effects on neonatal HIBD. Macamide B may become a new drug for the prevention and treatment of HIBD.


2012 ◽  
Vol 39 (6) ◽  
pp. 6495-6503 ◽  
Author(s):  
Huimin Dong ◽  
Shanpin Mao ◽  
Jiajun Wei ◽  
Baohui Liu ◽  
Zhaohui Zhang ◽  
...  

2019 ◽  
Vol 124 ◽  
pp. 110653 ◽  
Author(s):  
Nanqu Huang ◽  
Ying Zhang ◽  
Mingji Chen ◽  
Hai Jin ◽  
Jing Nie ◽  
...  

Author(s):  
ZiJun Liao ◽  
Qi Zheng ◽  
Ting Wei ◽  
YanBing Zhang ◽  
JieQun Ma ◽  
...  

MicroRNAs (miRNAs) play crucial roles in tumorigenesis and tumor progression. miR-561 has been reported to be downregulated in gastric cancer and affects cancer cell proliferation and metastasis. However, the role and underlying molecular mechanism of miR-561 in human non-small cell lung cancer (NSCLC) remain unknown and need to be further elucidated. In this study, we discovered that miR-561 expression was downregulated in human NSCLC tissues and cell lines. The overexpression of miR-561 inhibited NSCLC cell proliferation and cell cycle G1/S transition and induced apoptosis. The inhibition of miR-561 facilitated cell proliferation and G1/S transition and suppressed apoptosis. miR-561 expression was inversely correlated with P-REX2a expression in NSCLC tissues. P-REX2a was confirmed to be a direct target of miR-561 using a luciferase reporter assay. The overexpression of miR-561 decreased P-REX2a expression, and the suppression of miR-561 increased P-REX2a expression. Particularly, P-REX2a silencing recapitulated the cellular and molecular effects observed upon miR-561 overexpression, and P-REX2a overexpression counteracted the effects of miR-561 overexpression on NSCLC cells. Moreover, both exogenous expression of miR-561 and silencing of P-REX2a resulted in suppression of the PTEN/AKT signaling pathway. Our study demonstrates that miR-561 inhibits NSCLC cell proliferation and G1/S transition and induces apoptosis through suppression of the PTEN/AKT signaling pathway by targeting P-REX2a. These findings indicate that miR-561 plays a significant role in NSCLC progression and serves as a potential therapeutic target for NSCLC.


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