Cellular Lnc_209997 suppresses Bombyx mori nucleopolyhedrovirus replication by targeting miR-275-5p in B. mori

N-acetylglucosaminyl 1-phosphate transferase (GPT) is a facilitator in Bombyx mori Nucleopolyhedrovirus proliferation

GPT is a conserved ER-resident transmembrane protein that catalyzes the initial step of protein N-glycosylation in vertebrates. However, to date, there have been no reports on GPT in silkworms. In the present study, we identified a GPT ortholog in the B. mori genome. Spatiotemporal expression profiles showed that BmGPT was highly expressed in the majority of silkworm's organs. BmGPT regulates multiple cellular processes such as cell viability, proliferation, and cell death. In addition, BmGPT overexpression increased BmNPV proliferation in BmN cells, whereas BmGPT inhibition by siRNA or a chemical inhibitor suppressed BmNPV proliferation both in vitro and in vivo. These results suggested that BmGPT facilitates BmNPV proliferation by regulating cell proliferation and apoptosis. This study identifies a potential molecular target for BmNPV prevention and for silkworm breeding.

Bombyx mori UFBP1 regulates apoptosis and promotes BmNPV proliferation by affecting the expression of ER chaperone BmBIP

Ubiquitin-fold modifier 1 (UFM1) is attached to protein substrates through the sequential activity of an E1 (UBA5) - E2 (UFC1) - E3 (UFL1) cascade. UFBP1 is a conserved UFL1-interacting protein in mammals. However, to date, no study has been conducted on UFBP1 in silkworm. In this study, we identified a UFBP1 ortholog in the B. mori genome. Spatiotemporal expression profiles showed that BmUFBP1 expression was high in the midgut and fatbody, and at the moth stage. BmUFBP1 knockdown inhibited ER chaperone BmBIP expression and BmNPV proliferation, while BmUFBP1 overexpression increased BmNPV proliferation, and BmBIP rescued BmUFBP1-regulated BmNPV proliferation. Mechanistically, Apoptosis and ATF6 signaling are involved in BmUFBP1-regulated BmBIP expression and BmNPV proliferation. These results suggest that BmUFBP1 facilitates BmNPV proliferation via ATF6-BIP signaling, and provide a potential molecular target for BmNPV prevention and silkworm breeding.

Sublethal effects of nitenpyram on the development of silkworm

The utilization of nitenpyram for aphid and whitefly control may induce environmental contamination and negative repercussions on non-target organisms. Formerly, we found that nitenpyram would pollute the peripheral and sub-peripheral areas of the adjacent mulberry orchard. Under acute toxicity conditions, nitenpyram induced oxidative damage in silkworms, affected biological metabolism, synthesis, immunity, and signal transduction. Considering the impact of nitenpyram mist drift on mulberry leaves, we investigated the effects of low concentrations of nitenpyram on silkworms. The results showed that silkworms exposed to 0.17 mg/L, 0.35 mg/L and 0.70 mg/L of nitenpyram (1/40 LC50, 1/20 LC50 and 1/10 LC50) showed obvious poisoning symptoms. The cocoon weight and cocoon shell weight decreased gradually with increases in the concentration, and these decreases prolonged the growth and development time of silkworms and induced the detoxification enzymes carboxylesterase (CarE) and glutathione-S-transferase (GST) to cope with the stress damage caused by nitenpyram. Exposure to low concentrations of nitenpyram downregulates genes involved in the drug metabolism-other enzymes and peroxisome pathway in silkworms. Additionally, through injection of miRNA mimics and inhibitors, we discovered that detoxifying enzyme pathway genes are influenced by bmo-miR-3382-3P, bmo-miR-3213-5P and bmo-miR-133, regulating the immune response of silkworms. This study provides an overall view of the toxicity and detoxification metabolism of nitenpyram in silkworm, and provides a reference for environmental assessment.

Lnc557 promotes Bombyx mori nucleopolyhedrovirus replication by interacting with BmELAVL1 to enhance its stability and expression

Bombyx mori nucleopolyhedrovirus (BmNPV) is a major pathogen that threatens the growth and sustainability of the sericultural industry. Currently, accumulated studies showed that long non-coding RNAs (lncRNAs) play important roles in the genesis and progression of various viruses and host-pathogens interactions. However, the functions and regulatory mechanisms of lncRNAs in insect-virus interaction are still limited. In this study, transcriptome sequencing and ribosome profiling sequencing (Ribo-seq) were performed in the BmNPV-infected midgut and control tissue, and a total of 9 differentially expressed (DE) lncRNAs and 27 small ORFs (sORFs) with micropeptide coding potential were identified. Among them, lncRNA XR_001139971.3 (lnc557) is verified to be significantly up-regulated upon BmNPV infection and may have the potential to encode a small peptide (ORF-674). The subcellular localization experiment showed that lnc557 was expressed in the cytoplasm. Overexpression of lnc557 promotes BmNPV replication and vice versa. By combining RNA pull-down, mass spectrometry, protein truncation and RNA immunoprecipitation (RIP) assays, we confirmed that lnc557 can bind to the RRM-5 domain of BmELAVL1 protein. Subsequently, we found that lnc557 could promote the expression of BmELAVL1 by enhancing the stability of BmELAVL1. Further, enhancing the expression of BmELAVL1 can promote the proliferation of BmNPV, while knockdown shows the opposite effect. Our data suggest that lnc557-mediated BmELAVL1 expression enhancement could play a positive role in BmNPV replication, which will provide a new insight into the molecular mechanism of interaction between Bombyx mori and virus.

Study on anti-BmNPV mechanism of branched-chain amino acid aminotransferases in silkworm

Bombyx mori nucleopolyhedrovirus (BmNPV) is the most important virus that threatens sericulture industry. At present, there is no effective treatment for BmNPV infection in silkworms, and lncRNA plays an important role in biological immune response and host-virus interaction, but there are relatively few studies in silkworms. In this study, the four midgut tissue samples of the resistance strain NB (NB) and susceptible strain 306 (306) and the NB and 306 continuously infected with BmNPV for 96 h are used for whole transcriptome sequencing to analyze the differences in the genetic background of NB and 306 and the differences after inoculation of BmNPV, and the significantly different mRNA, miRNA and lnRNA between NB and 306 after BmNPV inoculation were screened. By comparing NB and 306, 2651 significantly different mRNAs, 57 significantly different miRNAs and 198 significantly different lncRNAs were screened. By comparing NB and 306 after BmNPV inoculation, 2684 significantly different mRNAs, 39 significantly different miRNAs and 125 significantly different lncRNAs were screened. According to the significantly different mRNA, miRNA and lncRNA screened from NB and 306 and NB and 306 after virus inoculation, the mRNA-miRNA-lncRNA regulatory network was constructed before and after virus inoculation, and the BmBCAT-Bomo_chr7_8305-MSTRG.3236.2 regulatory axis was screened from them, and it was found that BmBCAT was not Bomo_chr7_8305 regulated in the genetic background, after viral infection, MSTRG.3236.2 competes for binding Bomo_chr7_8305 regulates BmBCAT. The whole transcriptome sequencing results were verified by qPCR and the time-series expression analysis was performed to prove the reliability of the regulatory network. The BmBCAT-Bomo_chr7_8305-MSTRG.3236.2 regulatory axis may play a potential role in the interaction between silkworms and BmNPV. These results provide new insights into the interaction mechanism between silkworms and BmNPV.

Regulatory roles of long non-coding RNAs in short-term heat stress in adult worker bees

Long non-coding RNAs (lncRNAs) are crucial modulators of post-transcriptional gene expression regulation, cell fate determination, and disease development. However, lncRNA functions during short-term heat stress in adult worker bees are poorly understood. Here, we performed deep sequencing and bioinformatic analyses of honeybee lncRNAs. RNA interference was performed by using siRNA targeting the most highly expressed lncRNA. The silencing effect on lncRNA and the relative expression levels of seven heat shock protein (HSP) genes, were subsequently examined. Overall, 7,842 lncRNAs and 115 differentially expressed lncRNAs (DELs) were identified in adult worker bees following heat stress exposure. Structural analysis revealed that the overall expression abundance, length of transcripts, exon number, and open reading frames of lncRNAs were lower than those of mRNAs. GO analysis revealed that the target genes were mainly involved in "metabolism," "protein folding," "response to stress," and "signal transduction" pathways. KEGG analysis indicated that the "protein processing in endoplasmic reticulum" and "longevity regulating pathway-multiple species" pathways were most enriched. Quantitative real-time polymerase chain reaction (qRT-PCR) detection of the selected DELs confirmed the reliability of the sequencing data. Moreover, the siRNA experiment indicated that feeding siRNA yielded a silencing efficiency of 77.51% for lncRNA MSTRG.9645.5. Upon silencing this lncRNA, the expression levels of three HSP genes were significantly downregulated (p < 0.05), whereas those of three other HSP genes were significantly upregulated (p < 0.05). Our results provide a new perspective for understanding the regulatory mechanisms of lncRNAs in adult worker bees under short-term heat stress.

Identification of long noncoding RNAs of silkworm at the early stage of Bombyx mori bidensovirus infection

Bombyx mori bidensovirus (BmBDV) is one of the most important pathogens of silkworm. It mainly infects midgut cells of silkworm and causes losses to the sericulture industry. Long noncoding RNAs (lncRNAs) have been reported to play an important role in the regulation of antiviral immune response in silkworm. To explore whether lncRNAs are involved in BmBDV infection and immune response of silkworm, we performed a comparative transcriptome analysis to identify the lncRNAs and mRNAs between the BmBDV infected and noninfected silkworm larvae at the early stage. A total of 16,069 genes and 974 candidate lncRNAs were identified, among which 142 messenger RNA (mRNAs) and four lncRNAs were differentially expressed (DE). Target gene prediction revealed that 142 DEmRNAs were coexpressed with four DElncRNAs, suggesting that the expression of mRNA is mainly affected through trans-regulation activities. A regulatory network of DElncRNAs and DEmRNAs was constructed, showing that many genes targeted by different DElncRNAs are involved in metabolism and immunity, which implies that these genes and lncRNAs play an important role in the replication of BmBDV. Our results will help us to improve our understanding of lncRNA-mediated regulatory roles in BmBDV infection, providing a new perspective for further exploring the interaction between host and BmBDV.

Long non-coding RNAs regulate Aedes aegypti vector competence for Zika virus and reproduction

Long non-coding RNAs (lncRNAs) play critical regulatory roles in various cellular and metabolic processes in mosquitoes and all other organisms studied thus far. In particular, their involvement in essential processes such as reproduction makes them potential targets for the development of novel pest control approaches. However, their function in mosquito biology remains largely unexplored. To elucidate the role of lncRNAs in mosquitoes' reproduction and vector competence for arboviruses, we have implemented a computational and experimental pipeline to mine, screen, and characterize lncRNAs related to these two biological processes. Through analysis of publicly available Zika virus (ZIKV) infection-regulated Aedes aegypti transcriptomes, at least six lncRNAs were identified as being significantly upregulated in response to infection in various mosquito tissues. The roles of these ZIKV-regulated lncRNAs (designated Zinc1, Zinc2, Zinc3, Zinc9, Zinc10 and Zinc22), were further investigated by dsRNA-mediated silencing studies. Our results show that silencing of Zinc1, Zinc2, and Zinc22 renders mosquitoes significantly less permissive to ZIKV infection, while silencing of Zinc22 also reduces fecundity, indicating a potential role for Zinc22 in trade-offs between vector competence and reproduction. We also found that silencing of Zinc9 significantly increases fecundity but has no effect on ZIKV infection, suggesting that Zinc9 may be a negative regulator of oviposition. Our work demonstrates that some lncRNAs play host factor roles by facilitating viral infection in mosquitoes. We also show that lncRNAs can influence both mosquito reproduction and permissiveness to virus infection, two biological systems with important roles in mosquito vectorial capacity.

Multi-omics study and ncRNA regulation of anti-BmNPV in silkworms, Bombyx mori: an update

Bombyx mori silkworm is an important economic insect which has a significant contribution to the improvement of the economy. Bombyx mori nucleopolyhedrovirus (BmNPV) is a vitally significant purulent virus that impedes the sustainable and stable development of the silkworm industry, resulting in substantial economic losses. In recent years, with the development of biotechnology, transcriptomics, proteomics, metabolomics, and the related techniques have been used to select BmNPV-resistant genes, proteins, and metabolites. The regulatory networks between viruses and hosts have been gradually clarified with the discovery of ncRNAs, such as miRNA, lncRNA, and circRNA in cells. Thus, this paper aims to highlight the results of current multi-omics and ncRNA studies on BmNPV resistance in the silkworm, providing some references for resistant strategies in the silkworm to BmNPV.

LincRNA_XR209691.3 could promote Bombyx mori nucleopolyhedrovirus replication by interacting with BmHSP70

Long non-coding RNAs (lncRNAs), a class of transcripts exceeding 200 nucleotides and lacking protein coding potential, have been proven to play important roles in viral infection and host immunity. Bombyx mori nucleopolyhedrovirus (BmNPV) is an important pathogen, which causes the silkworm disease and leads to a huge challenge to the sericultural industry. At present, research on the roles of insect lncRNAs in host-virus interaction are relatively few. In this study, we explored the function of lincRNA_XR209691.3 that was significantly up-regulated in the silkworm fat body upon BmNPV infection. Firstly, the subcellular localization experiment confirmed that lincRNA_XR209691.3 was present in both the nucleus and cytoplasm. Enhancing the expression of lincRNA_XR209691.3 in BmN cells could promote the proliferation of BmNPV, while inhibition of lincRNA_XR209691.3 by RNA interference suppresses the proliferation of BmNPV. Combining RNA pull-down and mass spectrometry, we identified the host and BmNPV proteins that could interact with lincRNA_XR209691.3. Next, by using truncation experiment and RNA immunoprecipitation (RIP) assay, it was found that lincRNA_XR209691.3 could bind to the Actin domain of BmHSP70. Subsequently, overexpression of lncRNA_XR209691.3 in BmN cells promoted the expression of BmHSP70, while knockdown of BmHsp70 suppressed the replication of BmNPV. Based on the above results, it is speculated that lincRNA_XR209691.3 could promote the proliferation of BmNPV through interaction with BmHSP70, possibly by improving the stability of BmHSP70 and thereby enhancing the expression of BmHSP70. Our results shed light on the lncRNA function in insect-pathogen interactions and provide a new clue to elucidate the molecular mechanism of BmNPV infection.

Apoptosis-related long non-coding RNA LINC5438 of Bombyx mori promotes the proliferation of BmNPV

Apoptosis, as an important part of the immune response, is one of the core events in the host-virus interaction. Studies have shown that long non-coding RNAs (lncRNAs) play important roles in the process of cell apoptosis and pathophysiology. To investigate the apoptosis-related lncRNAs involved in Bombyx mori nucleopolyhedrovirus (BmNPV) infecting silkworms, transcriptome sequencing was conducted based on silkworm cells infected with BmNPV before and after B. mori inhibitor of apoptosis (Bmiap) gene knockout. A total of 23 differentially expressed lncRNAs were identified as being associated with the mitochondrial apoptosis pathway. Moreover, we demonstrated that B. mori LINC5438 has the function of inhibiting apoptosis in silkworm cells. Overexpression of LINC5438 promoted the proliferation of BmNPV, while interference with LINC5438 inhibited its proliferation, indicating that LINC5438 plays an important role in BmNPV infection. Our results also showed that LINC5438 can regulate the expression of Bmiap, BmDronc, BmICE, and its predicted target gene BmAIF, suggesting that LINC5438 may function through the mitochondrial pathway. These findings provide important insights into the mechanisms of virus-host interaction and the applications of baculoviruses as biological insecticides.

Recent Advances and Future Potential of Long Non-Coding RNAs in Insects

Over the last decade, long non-coding RNAs (lncRNAs) have witnessed a steep rise in interest amongst the scientific community. Because of their functional significance in several biological processes, i.e., alternative splicing, epigenetics, cell cycle, dosage compensation, and gene expression regulation, lncRNAs have transformed our understanding of RNA's regulatory potential. However, most knowledge concerning lncRNAs comes from mammals, and our understanding of the potential role of lncRNAs amongst insects remains unclear. Technological advances such as RNA-seq have enabled entomologists to profile several hundred lncRNAs in insect species, although few are functionally studied. This article will review experimentally validated lncRNAs from different insects and the lncRNAs identified via bioinformatic tools. Lastly, we will discuss the existing research challenges and the future of lncRNAs in insects.

Toxicity of nitenpyram to silkworm (Bombyx mori L.) and its potential mechanisms

Silkworm (Bombyx mori L.), as an economic insect, occupies a certain position in the development of China's economy. The neonicotinoid insecticide nitenpyram is commonly used in farmland to control planthoppers and aphids. In China, mulberry orchards are often planted adjacent to fields or commercial crops, and mist drifts occur during application, which may affect the production safety of Bombyx mori. In this study, a risk assessment of nitenpyram was carried out, and the results showed that there were risks in spraying nitenpyram around the periphery and subperipheries of mulberry fields. However, few studies have reported the mechanism underlying nitenpyram's toxic effect on silkworms. Here, we validated 25 differentially expressed (DE) miRNAs in the nitenpyram treatment group of silkworms, and the significantly enriched mTOR signaling pathway, oxidative phosphorylation and FoxO signaling pathway were verified. Among them, bmo-miR-2766-5P was up-regulated by 2.122-fold, and the expression of its regulated target gene 101,741,287 was up-regulated. After the injection of bmo-miR-2766-5P inhibitor, the Log₂FC value of 101,741,287 was changed from 1.26 to -2.19. Bmo-miR-3326, bmo-miR-3378-5P and bmo-miR-2761-3P were down-regulated by 2.386-fold, 1.158-fold and 2.359-fold, respectively. After injecting miRNA mimics into silkworms, the Log₂FC values of the target genes 100,302,609, 101,740,730 and 101,746,319 were changed from 1.24 to -11.94, -1.12 changed to 2.84 and 1.93 changed to -0.37, respectively. In addition, nitenpyram induced oxidative damage in silkworms, and the degree of DNA damage increased with the increase of concentration and time. Meanwhile Imd was significantly up-regulated in IMD-related pathways (38.7-fold, p < 0.01). The results indicated that nitenpyram could affect the growth and development process of silkworms, and these DE-miRNAs may have an important impact on the stress response of silkworms to nitenpyram.