Innexin hemichannel activation by Microplitis bicoloratus ecSOD monopolymer reduces ROS.

The extracellular superoxide dismutases (ecSODs) secreted by Microplitis bicoloratus reduce the reactive oxygen species (ROS) stimulated by the Microplitis bicoloratus bracovirus. Here, we demonstrate that the bacterial transferase hexapeptide (hexapep) motif and bacterial-immunoglobulin-like (BIg-like) domain of ecSODs bind to the cell membrane and transiently open hemichannels, facilitating ROS reductions. RNAi-mediated ecSOD silencing in vivo elevated ROS in host hemocytes, impairing parasitoid larva development. In vitro, the ecSOD-monopolymer needed to be membrane bound to open hemichannels. Furthermore, the hexapep motif in the beta-sandwich of ecSOD49 and ecSOD58, and BIg-like domain in the signal peptides of ecSOD67 were required for cell membrane binding. Hexapep motif and BIg-like domain deletions induced ecSODs loss of adhesion and ROS reduction failure. The hexapep motif and BIg-like domain mediated ecSOD binding via upregulating innexins and stabilizing the opened hemichannels. Our findings reveal a mechanism through which ecSOD reduces ROS, which may aid in developing anti-redox therapy.

Simulating immunosuppressive mechanism of Microplitis bicoloratus bracovirus coordinately fights Spodoptera frugiperda.

Parasitoid wasps control pests via a precise attack leading to the death of the pest. However, parasitoid larvae exhibit self-protection strategies against bracovirus-induced reactive oxygen species impairment. This has a detrimental effect on pest control. Here, we report a strategy for simulating Microplitis bicoloratus bracovirus using Mix-T dsRNA targeting 14 genes associated with transcription, translation, cell-cell communication, and humoral signaling pathways in the host, and from wasp extracellular superoxide dismutases. We implemented either one-time feeding to the younger instar larvae or spraying once on the corn leaves, to effectively control the invading pest Spodoptera frugiperda. This highlights the conserved principle of "biological pest control," as elucidated by the triple interaction of parasitoid-bracovirus-host in a cooperation strategy of bracovirus against its pest host.

Expression level comparison of marker genes related to early embryonic development and tumor growth.

In tumor research, the occurrence and origin of tumors are the fundamental problems. In the 1970s, the basic discussion of the developmental biology problem of tumors was proposed, and it was believed that tumorigenesis is closely related to developmental biology. Tumors are abnormal biological structures in organisms, and their biological behavior is very similar to that of the early embryo. Many tumor-related genes also serve regulatory roles in the normal development and differentiation of embryos. However, it remains unclear whether gene expression in early embryos has any similarities with tumor cells. In this study, to compare the similarities and differences in gene expression between early embryos and tumor cells, reverse transcription-quantitative PCR was conducted to determine and compare the relative expression levels of nine tumor-related genes in the brain glioma cell line, T98G, and in the early embryo of Spodoptera litura, which is fast-growing, low-cost, easily accessible and easy to observe. The expression of tumor-related genes in early embryos and the similarity of regulatory mechanisms between early embryonic development and tumor growth were explored. In conclusion, tumor growth may be regarded as an abnormal embryogenic activation that happens in the organs of adult individuals.

Bracovirus Sneaks Into Apoptotic Bodies Transmitting Immunosuppressive Signaling Driven by Integration-Mediated eIF5A Hypusination.

A typical characteristics of polydnavirus (PDV) infection is a persistent immunosuppression, governed by the viral integration and expression of virulence genes. Recently, activation of caspase-3 by Microplitis bicoloratus bracovirus (MbBV) to cleave Innexins, gap junction proteins, has been highlighted, further promoting apoptotic cell disassembly and apoptotic body (AB) formation. However, whether ABs play a role in immune suppression remains to be determined. Herein, we show that ABs transmitted immunosuppressive signaling, causing recipient cells to undergo apoptosis and dismigration. Furthermore, the insertion of viral-host integrated motif sites damaged the host genome, stimulating eIF5A nucleocytoplasmic transport and activating the eIF5A-hypusination translation pathway. This pathway specifically translates apoptosis-related host proteins, such as P53, CypA, CypD, and CypJ, to drive cellular apoptosis owing to broken dsDNA. Furthermore, translated viral proteins, such Vank86, 92, and 101, known to complex with transcription factor Dip3, positively regulated DHYS and DOHH transcription maintaining the activation of the eIF5A-hypusination. Mechanistically, MbBV-mediated extracellular vesicles contained inserted viral fragments that re-integrated into recipients, potentially via the homologous recombinant repair system. Meanwhile, this stimulation regulated activated caspase-3 levels via PI3K/AKT 308 and 473 dephosphorylation to promote apoptosis of granulocyte-like recipients Sf9 cell; maintaining PI3K/AKT 473 phosphorylation and 308 dephosphorylation inhibited caspase-3 activation leading to dismigration of plasmatocyte-like recipient High Five cells. Together, our results suggest that integration-mediated eIF5A hypusination drives extracellular vesicles for continuous immunosuppression.

Artemether Attenuates Aß25-35-Induced Cognitive Impairments by Downregulating Aß, BACE1, mTOR and Tau Proteins.

BACKGROUND: Alzheimer's disease (AD) is clinically characterized as a progressive cognitive impairment and behavioral disorder. Pathological hallmarks of AD include extracellular senile plaques (SPs), intracellular neurofibrillary tangles (NFTs) and massive neuronal loss. Although the exact cause of AD is not well understood, a mounting body of evidence has demonstrated that the pathogenesis of AD is associated with oxidative stress, neu-roinflammation, and amyloid beta (Aß) induced neural apoptosis. Moreover, overexpression of ß-secretase 1 (BACE1), Aß, mammalian target of rapamycin (mTOR), and Tau proteins are closely related to cognitive symptoms in AD. Studies have demonstrated that artemether, an antimalarial drug with acceptable side effects, possesses protective effects against neuroinflammation and oxidative stress. Importantly, artemether can easily penetrate the blood brain barrier, thereby representing an ideal drug candidate for AD treatment. METHODS: The effect of artemether on memory protection and the associated molecular mechanisms were investigated in an Aß25-35 induced cognitive impairments rat model. RESULTS: Results of the in vivo study showed that oral administration of artemether significantly attenuated Aß25-35-induced cognitive impairment in rats. Results of the in vitro study revealed that artemether significantly downregulated the endogenous expression of Aß, BACE1, mTOR, and Tau proteins in N2a cells. CONCLUSIONS: The beneficial effect of artemether against Aß 25-35-induced cognitive impairments was attributable to the downregulation of the expression of Aß, BACE1, mTOR, and Tau proteins, suggesting the potential of artemether as an effective, neuronal protective, and multi-targeted drug candidate for AD treatment.

The Association of microRNA-34a With High Incidence and Metastasis of Lung Cancer in Gejiu and Xuanwei Yunnan.

The incidence and associated mortality of lung cancer in tin miners in Gejiu County and farmers in Xuanwei Country, Yunnan Province have been very high in the world. Current published literatures on the molecular mechanisms of lung cancer initiation and progression in Gejiu and Xuanwei County are still controversial. Studies confirmed that microRNA-34a (miR-34a) functioned as a vital tumor suppressor in tumorigenesis and progression. However, the role and precise mechanisms of miR-34a and its regulatory gene network in initiation and progression of lung cancer in Gejiu and Xuanwei County, Yunnan Province, have not been elucidated. In the current study, we first found that miR-34a was downregulated in Gejiu lung squamous carcinoma YTMLC-90, Xuanwei lung adenocarcinoma XWLC-05, and other non-small cell lung carcinoma (NSCLC) cell lines, and miR-34a overexpression inhibited cell proliferation, migration and invasion, as well as induced cell apoptosis in YTMLC-90 and XWLC-05 cells. Our findings revealed that miR-34a is critical and cannot be considered as the area-specific non-coding RNA in initiation and progression of lung cancer in Gejiu and Xuanwei County. Next we revealed that miR-34a overexpression suppressed lung cancer growth and metastasis partially via increasing PTEN but reducing CDK6 expression that might lead to subsequent inactivation of PI3K/AKT pathway. Furthermore, our findings demonstrated that YY1 functioned as a tumor suppressor gene in initiation and progression of lung cancer in Gejiu and Xuanwei County. In conclusion, our findings in the study confirmed that miR-34a overexpression could simultaneously suppress tumor growth and metastasis and play a vital role in tumorigenesis and progression of NSCLC via increasing PTEN and YY1 expression, but decreasing CDK6. Most interestingly, our findings also raised doubts about the current ideas about these area-specific diseases.

Bracovirus-mediated innexin hemichannel closure in cell disassembly.

Cell-cell communication is necessary for cellular immune response. Hemichannel closure disrupts communication between intracellular and extracellular environments during polydnavirus-induced immunosuppression in invertebrates. However, the effects of hemichannel closure on cellular immune response are unclear. Here, we examined apoptotic body formation triggered by hemichannel closure in hemocytes of Spodoptera litura infected with bracovirus from the parasitic wasp, Microplitis bicoloratus. We showed that Microplitis bicoloratus bracovirus (MbBV) induced apoptotic cell disassembly, accompanied by hemichannel closure. Hemocyte apoptotic body formation was caused by the dysregulation of the innexins (Inxs), Inx1, Inx2, Inx3, and Inx4, during the MbBV-mediated inhibition of pI3K/AKT signaling and activation of caspase-3, which cleaved gap junction Inx proteins. Our results showed that hemichannel opening or closure in response to various stimuli, which induces the modulation of Inx levels, could inhibit or activate apoptotic body formation, respectively. Therefore, the "hemichannel open and close" model may regulate the cellular immune response.

Interactions of Vank proteins from Microplitis bicoloratus bracovirus with host Dip3 suppress eIF4E expression.

Microplitis bicoloratus bracovirus (MbBV) inhibits the immune response of the host Spodoptera litura by disrupting nuclear factor (NF)-κB signaling and downstream gene expression. However, the underlying molecular mechanisms are not well understood. Herein, we report that viral ankyrin (Vank) proteins interacted with host dorsal-interacting protein 3 (Dip3) to selectively inhibit the transcription of eukaryotic translation initiation factor 4 E (eIF4E). Dip3 and Vank proteins were co-expressed and colocalized in the nucleus. Furthermore, ectopic expression of Dip3 rescued the transcription of some NF-κB-dependent genes suppressed by Vank proteins, including eIF4E. Co-immunoprecipitation and pull-down assays confirmed that Vank proteins interacted with and bound to full-length Dip3, which including MADF, DNA-binding protein, BESS, and protein-protein interaction motifs as well as non-motif sequences. In vivo, RNAi-mediated dip3 silencing decreased eIF4E levels and was accompanied by an immunosuppressive phenotype in S. litura. Our results provided novel insights into the regulation of host transcription during immune suppression by viral proteins that modulate nuclear NF-κB signaling.

Effects and mechanism of microRNA­218 against lung cancer.

Lung cancer is the most prevalent and observed type of cancer in Xuanwei County, Yunnan, South China. Lung cancer in this area is called Xuanwei lung cancer. However, its pathogenesis remains largely unknown. To date, a number of studies have shown that microRNA (miR)­218 functions as a tumor suppressor in multiple types of cancer. However, the role of miR­218 and its regulatory gene network in Xuanwei lung cancer have yet to be investigated. The current study identified that the expression levels of miR­218 in XWLC­05 cells were markedly lower compared with those in immortalized lung epithelial BEAS­2B cells. The present study also demonstrated that overexpression of miR­218 could decrease cell proliferation, invasion, viability and migration in Xuanwei lung cancer cell line XWLC­05 and NSCLC cell line NCI­H157. Additionally, the results revealed that overexpression of miR­218 could induce XWLC­05 and NCI­H157 cell apoptosis by arresting the cell cycle at G2/M phase. Finally, the present study demonstrated that overexpression of miR­218 could lead to a significant increase in phosphatase and tensin homolog (PTEN) and YY1 transcription factor (YY1), and a decrease in B­cell lymphoma 2 (BCL­2) and BMI1 proto­oncogene, polycomb ring finger (BMI­1) at the mRNA and protein level in XWLC­05 and NCI­H157 cell lines. However, we did not observe any remarkable difference in the roles of miR­218 and miR­218­mediated regulation of BCL­2, BMI­1, PTEN and YY1 expression in the progression of Xuanwei lung cancer. In conclusion, miR­218 could simultaneously suppress cell proliferation and tumor invasiveness and induce cell apoptosis by increasing PTEN and YY1 expression, while decreasing BCL­2 and BMI­1 in Xuanwei lung cancer. The results demonstrated that miR­218 might serve a vital role in tumorigenesis and progression of Xuanwei lung cancer and overexpression of miR­218 may be a novel approach for the treatment of Xuanwei lung cancer.

Cryo-EM structure reveals cylindrical nucleocapsids from two polydnaviruses.

Bracovirus is one of the two polydnavirus genera. Here, we used a cryo-EM analysis to reveal the near-native morphology of two nucleocapsid-containing model bracoviruses: Microplitis bicoloratus bracovirus (MbBV) and Microplitis mediator bracovirus (MmBV). MbBV and MmBV nucleocapsids have discernable cap structures in two distal regions with relatively high electron density. Adjacent to the end-cap structures are two electron-lucent rings. Some nucleocapsids were uniformly electron-dense and had a distinctive "helix-tail-like structure". Cryo-EM revealed inconsistent nucleocapsid diameters of 34-69.9 nm in MbBV and 46-69.9 nm in MmBV, and the largest observed cylindrical area length was expanded to 126 nm.

Inhibition of translation initiation factor eIF4A is required for apoptosis mediated by Microplitis bicoloratus bracovirus.

Apoptotic hemocytes induced by Microplitis bicoloratus parasitism have been reported, and M. bicoloratus bracovirus (MbBV) is known to be the apoptosis inducer. However, the mechanism how MbBV regulates apoptosis remains unclear. eIF4A, one of translation initiation factors, was found from a Spodoptera litura transcriptome, the expression of which in the parasitized hemocytes of S. litura was inhibited in RT-qPCR analysis. The western blot also illustrated eIF4A at 6-day post-parasitization was inhibited in hemocytes. For testing interaction of MbBV-eIF4A-apoptosis, a cDNA clone encoding 1,266 bp of eIF4A was obtained from S. litura hemocytes and sequenced. Then, a 48 kDa V5-fusion protein of the eIF4A was detected by using the anti-V5 antibody at 72-h post-transfection in the High Five cells, which is located in the cell cytoplasm. In vitro, overexpression of eIF4A rescued the apoptotic High Five cells induced by MbBV. Conversely, in vivo, loss of eIF4A proteins by dsRNA feeding increased apoptosis of hemocytes. Furthermore, RNAi and parasitism significantly increased apoptosis of hemocytes in S. litura. These findings suggested that MbBV inhibited the expression of eIF4A, which was required for apoptosis mediated by MbBV. This study will contribute to biological pest control and enhance our understanding of molecular mechanisms underlying polydnavirus-parasitoid-host interaction.