Wolbachia Utilizes lncRNAs to Activate the Anti-Dengue Toll Pathway and Balance Reactive Oxygen Species Stress in Aedes aegypti Through a Competitive Endogenous RNA Network

Abstract

Long non-coding RNAs (lncRNA), a class of RNA molecules without protein coding potential, are more than 200 nucleotides in length and widely present in a variety of species. Although increasing progress in regard to the determination of lncRNA function has been made in vertebrates, Aedes aegypti lncRNAs were only identified recently and the functions of few lncRNAs have been annotated so far. Herein, the genome-wide alteration of the lncRNA expression profile trigged by Wolbachia wAlbB infection was investigated by comparing A. aegypti Aag2 cells and W-Aag2 cells infected with Wolbachia wAlbB. Based on lncRNA sequencing, 3035 differentially expressed lncRNAs (DE lncRNAs) in total were identified upon Wolbachia infection, which were further validated by quantitative PCR. The constructed co-expression network of DE lncRNAs and mRNAs revealed that Wolbachia-induced DE lncRNAs were highly enriched in the oxidative phosphorylation pathway via trans-activity, according to the KEGG pathway enrichment analyses. In addition, the established competitive endogenous RNA (ceRNA) network identifies the DE lncRNAs enriched in cellular oxidant detoxification based on GO enrichment analysis. Furthermore, silencing of aae-lnc-7598, the significantly up-regulated lncRNA with the highest fold change induced by Wolbachia, caused a significant reduction of antioxidant catalase 1B (CAT1B) gene expression as well as the enhancement of mitochondrial reactive oxygen species (ROS) production in living cells. These findings indicate that Wolbachia manipulates lncRNA to balance intracellular ROS stress and ensure its endosymbiosis in host A. aegypti. Notably, the function assay demonstrated that aae-lnc-0165 suppressed by Wolbachia could induce expression of the REL1 gene, the key regulator of downstream Toll pathway, through the sequence-specific binding of aae-miR-980-5p, which contributes to the activation of Toll pathway. Moreover, the depletion of aae-lnc-0165 caused the suppression of mitochondrial ROS levels in living cells. Our data reveal that Wolbachia activates the anti-dengue Toll pathway through a lncRNA-ceRNA pattern. Taken together, our finding suggested that Wolbachia utilizes lncRNAs to activate host anti-dengue Toll pathway via a ceRNA network. Moreover, Wolbachia employs lncRNAs to ensure ROS homeostasis for ROS-based anti-dengue defense through either trans-regulation or the ceRNA network. This study identifies novel potential molecular biomarkers for prevention and control of epidemic dengue.

Comprehensive investigation and regulatory function of lncRNAs engaged in western honey bee larval immune response to Ascosphaera apis invasion

“…An increasing number of lncRNAs have been verified to be pivotal regulators in the occurrence and development of an array of human diseases through ceRNA mechanisms, such as cancer, Alzheimer's disease, and cardiovascular disease (Wu et al, 2020;Ma et al, 2020). Additionally, lncRNAs were suggested to mediate insectpathogen interactions via ceRNA regulatory networks (Chen et al, 2019a;Mao et al, 2022). For example, Mao et al (2022) reported that aae-lnc-0165 suppressed by Wolbachia induced the expression of Frontiers in Physiology frontiersin.org REL1 gene in Aedes aegypti through the sequence-specific binding of aae-miR-980-5p, which contributed to the activation of Toll signaling pathway.…”

“…Additionally, lncRNAs were suggested to mediate insectpathogen interactions via ceRNA regulatory networks (Chen et al, 2019a;Mao et al, 2022). For example, Mao et al (2022) reported that aae-lnc-0165 suppressed by Wolbachia induced the expression of Frontiers in Physiology frontiersin.org REL1 gene in Aedes aegypti through the sequence-specific binding of aae-miR-980-5p, which contributed to the activation of Toll signaling pathway. Previous findings showed that lncRNA-mediated ceRNA regulatory networks were putatively engaged in midgut development and the N. ceranae response of western honey bee workers (Guo et al, 2018;Chen et al, 2019a).…”

Small Talk: On the Possible Role of Trans-Kingdom Small RNAs during Plant–Virus–Vector Tritrophic Communication

“…The strategy to trans-activate RNAi also works when dsRNA is expressed in a transgenic plant and ingested by the Colorado beetle upon feeding [ 106 ], and altogether shows that insects can be affected by ingestion and uptake of dsRNA from external sources. In another very recent study, a long-noncoding RNA lncRNA molecule from the endosymbiont Wolbachia was found to activate anti-dengue defense pathway in Aedes aegypti mosquitoes, indicating the possibilities of ncRNA communication and modulation of virus insect vectors [ 107 ]. Findings such as these, and the important role of endosymbionts in the life cycle of insect pests and/or virus transmission, have also tempted researchers to elaborate on symbiont-mediated RNAi in aphids [ 108 ].…”

The emerging roles of long non-coding RNA in host immune response and intracellular bacterial infections

“…Further, competitive endogenous RNA (ceRNA) network analysis showed these lncRNA enriched for cellular oxidant detoxification pathway. Of them, lncRNA aae-lnc-7598 had the highest upregulation (Mao et al, 2022). Silencing of aae-lnc-7598 resulted in significant downregulation of antioxidant catalase 1B (CAT1B) gene and increase in mitochondria-mediated reactive oxygen species (ROS) in host cells.…”

“…Silencing of aae-lnc-7598 resulted in significant downregulation of antioxidant catalase 1B (CAT1B) gene and increase in mitochondria-mediated reactive oxygen species (ROS) in host cells. Another lncRNA, aae-lnc-0165 was downregulated after Wolbachia infection in host cells, which increased expression of REL1 through binding of aae-miRNA-980-5p, leading to Toll activation (Mao et al, 2022). Notably, these lncRNAs activate the anti-Dengue Toll pathway during Wolbachia infection.…”