Interaction of lncRNA-CR33942 with Dif/Dorsal Facilitates Antimicrobial Peptide Transcriptions and Enhances Drosophila Toll Immune Responses

Berberine hydrochloride enhances innate immunity to protect against pathogen infection via p38 MAPK pathway

The p38 MAPK pathway, an evolutionarily conserved mechanism, plays a crucial role in defending hosts against bacterial infections in both mammals and nematodes. Activating p38 MAPK signaling has been identified as a promising strategy to strengthen innate immunity and enhance resistance to pathogenic infections across various organisms.Berberine hydrochloride (BH), an isoquinoline alkaloid derived from Coptis, is known for its diverse biological activities, including anticancer, antibacterial, anti-inflammatory, lipid-lowering, and hepatoprotective effects. However, its impact on innate immunity and the associated molecular mechanisms remains unclear. In this study, we discovered that 10 μM Berberine hydrochloride enhanced resistance against both Gram-negative pathogens, such as Pseudomonas aeruginosa, Salmonella enterica and Gram-positive pathogen Listeria monocytogenes. Notably, Berberine hydrochloride improved pathogen resistance by reducing bacterial load in the intestine. Screening of classical innate immune pathways in Caenorhabditis elegans revealed that Berberine hydrochloride conferred protection against infections through the p38 MAPK pathway, specifically by activating p38/PMK-1 signaling in the intestine to bolster innate immunity. Furthermore, Berberine hydrochloride also stimulated innate immunity in mice via the p38 MAPK pathway and significantly reduced bacterial load in the lungs. These findings indicate that Berberine hydrochloride may have therapeutic potential for protecting host from infectious diseases.

Comprehensive analysis of lncRNAs and mRNAs revealed potential participants in the process of avian reovirus infection

Avian reovirus (ARV), a double-stranded RNA virus, frequently induces immunosuppression in poultry, leading to symptoms such as irregular bleeding and spleen necrosis in infected ducks. Since 2017, the morbidity and mortality rates associated with ARV infection in poultry have been on the rise, progressively emerging as a significant viral disease impacting the duck farming industry in China. In our study, we collected duck embryo fibroblasts 18 h post-infection with ARV and conducted transcriptome sequencing analysis. The analysis revealed that 3,818 mRNA expressions were up-regulated, 4,573 mRNA expressions were down-regulated, 472 long noncoding RNAs (LncRNAs) were up-regulated, and 345 lncRNAs were down-regulated. We employed qRT-PCR to validate the sequencing results, confirming their accuracy. The transcriptome data indicated significant upregulation of the PARP9, TLR7, TRIM33, and ATG5 genes, suggesting their potential involvement in ARV infection. Notably, our study identified a novel functional lncRNA, MSTRG.9284.1 (It was named linc000889 in the present study), which inhibits the replication of ARV at the transcriptional, translational levels and viral titer. Overall, this study has identified numerous ARV-induced differentially expressed mRNAs and lncRNAs, including the functional lncRNA linc000889 that inhibits ARV replication. This discovery provides new insights into the mechanisms of ARV infection and may contribute to the development of new prevention and treatment strategies.

NF-κB factors cooperate with Su(Hw)/E4F1 to balance Drosophila/human immune responses via modulating dynamic expression of miR-210

MicroRNAs (miRNAs) play crucial regulatory roles in controlling immune responses, but their dynamic expression mechanisms are poorly understood. Here, we firstly confirm that the conserved miRNA miR-210 negatively regulates innate immune responses of Drosophila and human via targeting Toll and TLR6, respectively. Secondly, our findings demonstrate that the expression of miR-210 is dynamically regulated by NF-κB factor Dorsal in immune response of Drosophila Toll pathway. Thirdly, we find that Dorsal-mediated transcriptional inhibition of miR-210 is dependent on the transcriptional repressor Su(Hw). Mechanistically, Dorsal interacts with Su(Hw) to modulate cooperatively the dynamic expression of miR-210 in a time- and dose-dependent manner, thereby controlling the strength of Drosophila Toll immune response and maintaining immune homeostasis. Fourthly, we reveal a similar mechanism in human cells, where NF-κB/RelA cooperates with E4F1 to regulate the dynamic expression of hsa-miR-210 in the TLR immune response. Overall, our study reveals a conservative regulatory mechanism that maintains animal innate immune homeostasis and provides new insights into the dynamic regulation of miRNA expression in immune response.

The ncRNA-mediated regulatory networks of defensins and lysozymes in Riptortus pedestris: involvement in response to gut bacterial disturbances

Insects depend on humoral immunity against intruders through the secretion of antimicrobial peptides (AMPs) and immune effectors via NF-κB transcription factors, and their fitness is improved by gut bacterial microbiota. Although there are growing numbers of reports on noncoding RNAs (ncRNAs) involving in immune responses against pathogens, comprehensive studies of ncRNA-AMP regulatory networks in Riptortus pedestris, which is one of the widely distributed pests in East Asia, are still not well understood under feeding environmental changes. The objective of this study employed the whole-transcriptome sequencing (WTS) to systematically identify the lncRNAs (long noncoding RNA) and circRNAs (circular RNA) and to obtain their differential expression from the R. pedestris gut under different feeding conditions. Functional annotation indicated that they were mainly enriched in various biological processes with the GO and KEGG databases, especially in immune signaling pathways. Five defensin (four novel members) and eleven lysozyme (nine novel members) family genes were identified and characterized from WTS data, and meanwhile, phylogenetic analysis confirmed their classification. Subsequently, the miRNA-mRNA interaction network of above two AMPs and lncRNA-involved ceRNA (competing endogenous RNA) regulatory network of one lysozyme were predicted and built based on bioinformatic prediction and calculation, and the expression patterns of differentially expressed (DE) defensins, and DE lysozymes and related DE ncRNAs were estimated and selected among all the comparison groups. Finally, to integrate the analyses of WTS and previous 16S rRNA amplicon sequencing, we conducted the Pearson correlation analysis to reveal the significantly positive or negative correlation between above DE AMPs and ncRNAs, as well as most changes in the gut bacterial microbiota at the genus level of R. pedestris. Taken together, the present observations provide great insights into the ncRNA regulatory networks of AMPs in response to rearing environmental changes in insects and uncover new potential strategies for pest control in the future.

The utility of Drosophila melanogaster as a fungal infection model

Invasive fungal diseases have profound effects upon human health and are on increase globally. The World Health Organization (WHO) in 2022 published the fungal priority list calling for improved public health interventions and advance research. Drosophila melanogaster presents an excellent model system to dissect host-pathogen interactions and has been proved valuable to study immunopathogenesis of fungal diseases. In this review we highlight the recent advances in fungal-Drosophila interplay with an emphasis on the recently published WHO's fungal priority list and we focus on available tools and technologies.

Relish-facilitated lncRNA-CR11538 suppresses Drosophila Imd immune response and maintains immune homeostasis via decoying Relish away from antimicrobial peptide promoters

Innate immunity plays a crucial role in host defense against pathogen invasion and its strength and duration requires precise control. Long non-coding RNAs (lncRNAs) have become important regulators of innate immunity, yet their roles in Drosophila immune responses remain largely unknown. In this study, we identified that the overexpression of lncRNA-CR11538 inhibits the expression of antimicrobial peptides (AMPs) Dpt and AttA in Drosophila upon Escherichia coli (E. coli) infection, and influences the survival rate of flies after E. cloacae infection. Mechanically, lncRNA-CR11538 decoys Relish away from AMPs promoter region. We further revealed that Relish can promote the transcription of lncRNA-CR11538. After analyzing the dynamic expression profile of lncRNA-CR11538 during Imd immune response, we put forward a hypothesis that in the late stage of Imd immune response, lncRNA-CR11538 can be activated by Relish and further decoy Relish away from the AMPs promoter to suppress excessive immune signal and maintain immune homeostasis. This mechanism we proposed provides insights into the complex regulatory networks controlling immune responses in Drosophila and suggests potential targets for therapeutic intervention in diseases involving dysregulated immune responses.

The identification of regulatory ceRNA network involved in Drosophila Toll immune responses

Non-coding RNAs play important roles in the innate immunity of Drosophila, with various lncRNAs and miRNAs identified to maintain Drosophila innate immune homeostasis by regulating protein functions. However, it remains unclear whether interactions between lncRNAs and miRNAs give rise to a ceRNA network. In our previous study, we observed the highest differential expression levels of lncRNA-CR11538, lncRNA-CR33942, and lncRNA-CR46018 in wild-type flies after Gram-positive bacterial infection, prompting us to investigate their role in the regulation of Drosophila Toll immune response through RNA-seq analysis. Herein, our comprehensive bioinformatics analysis revealed that lncRNA-CR11538, lncRNA-CR33942, and lncRNA-CR46018 are involved in defense mechanisms and stimulus response. Moreover, lncRNA-CR11538 and lncRNA-CR46018 can also participate in the metabolic recovery processes following Gram-positive bacterial infection. Subsequently, we employed GSEA screening and RT-qPCR to identify seven miRNAs (miR-957, miR-1015, miR-982, miR-993, miR-1007, miR-193, and miR-978) that may be regulated by these three lncRNAs. Furthermore, we predicted the potential target genes in the Toll signaling pathway for these miRNAs and their interaction with the three lncRNAs using TargetScan and miRanda software and preliminary verification. As a result, we established a potential ceRNA regulatory network for Toll immune responses in Drosophila, comprising three lncRNAs and seven miRNAs. This study provides evidence of a ceRNA regulatory network in Drosophila Toll immune responses and offers novel insights into understanding the regulatory networks involved in the innate immunity of other animals.

Representation of non-coding RNA-mediated regulation of gene expression using the Gene Ontology

Regulatory non-coding RNAs (ncRNAs) are increasingly recognized as integral to the control of biological processes. This is often through the targeted regulation of mRNA expression, but this is by no means the only mechanism through which regulatory ncRNAs act. The Gene Ontology (GO) has long been used for the systematic annotation of protein-coding and ncRNA gene function, but rapid progress in the understanding of ncRNAs meant that the ontology needed to be revised to accurately reflect current knowledge. Here, a targeted effort to revise GO terms used for the annotation of regulatory ncRNAs is described, focusing on microRNAs (miRNAs), long non-coding RNAs (lncRNAs), small interfering RNAs (siRNAs) and PIWI-interacting RNAs (piRNAs). This paper provides guidance to biocurators annotating ncRNA-mediated processes using the GO and serves as background for researchers wishing to make use of the GO in their studies of ncRNAs and the biological processes they regulate.

The lncRNA-mediated ceRNA network of Altica viridicyanea is involved in the regulation of the Toll/Imd signaling pathway under antibiotic treatment

Long noncoding RNAs (lncRNAs) play significant roles in the regulation of mRNA expression or in shaping the competing endogenous RNA (ceRNA) network by targeting miRNA. The insect gut is one of the most important tissues due to direct contact with external pathogens and functions in the immune defense against pathogen infection through the innate immune system and symbionts, but there are limited observations on the role of the lncRNA-involved ceRNA network of the Toll/Imd pathway and correlation analysis between this network and bacterial microbiota in the Altica viridicyanea gut. In this research, we constructed and sequenced six RNA sequencing libraries using normal and antibiotic-reared samples, generating a total of 17,193 lncRNAs and 26,361 mRNAs from massive clean data by quality control and bioinformatic analysis. Furthermore, a set of 8,539 differentially expressed lncRNAs (DELs) and 13,263 differentially expressed mRNAs (DEMs), of which related to various immune signaling pathways, such as the Toll/Imd, JAK/STAT, NF-κB, and PI3K-Akt signaling pathways, were obtained between the two experimental groups in A. viridicyanea. In addition, numerous GO and KEGG enrichment analyses were used to annotate the DELs and their target genes. Moreover, six Toll family members and nineteen signal genes from the Toll/Imd signaling pathway were identified and characterized using online tools, and phylogenetic analyses of the above genes proved their classification. Next, a lncRNA-miRNA-mRNA network of the Toll/Imd pathway was built, and it contained different numbers of DEMs in this pathway and related DELs based on prediction and annotation. In addition, qRT-PCR validation and sequencing data were conducted to show the expression patterns of the above DELs and DEMs related to the Toll/Imd signaling pathway. Finally, the correlated investigations between DELs or DEMs of the Toll/Imd signaling pathway and most changes in the gut bacterial microbiota revealed significantly positive or negative relationships between them. The present findings provide essential evidence for innate immune ceRNAs in the beetle gut and uncover new potential relationships between innate immune pathways and the gut bacterial microbiota in insects.

Drosophila immune priming to Enterococcus faecalis relies on immune tolerance rather than resistance

Innate immune priming increases an organism's survival of a second infection after an initial, non-lethal infection. We used Drosophila melanogaster and an insect-derived strain of Enterococcus faecalis to study transcriptional control of priming. In contrast to other pathogens, the enhanced survival in primed animals does not correlate with decreased E. faecalis load. Further analysis shows that primed organisms tolerate, rather than resist infection. Using RNA-seq of immune tissues, we found many genes were upregulated in only primed flies, suggesting a distinct transcriptional program in response to initial and secondary infections. In contrast, few genes continuously express throughout the experiment or more efficiently re-activate upon reinfection. Priming experiments in immune deficient mutants revealed Imd is largely dispensable for responding to a single infection but needed to fully prime. Together, this indicates the fly's innate immune response is plastic-differing in immune strategy, transcriptional program, and pathway use depending on infection history.

Genome-wide identification of lncRNAs associated with viral infection in Spodoptera frugiperda

The role of lncRNAs in immune defence has been demonstrated in many multicellular and unicellular organisms. However, investigation of the identification and characterization of long non-coding RNAs (lncRNAs) involved in the insect immune response is still limited. In this study, we used RNA sequencing (RNA-seq) to investigate the expression profiles of lncRNAs and mRNAs in the fall armyworm Spodoptera frugiperda in response to virus infection. To assess the tissue- and virus-specificity of lncRNAs, we analysed and compared their expression profiles in haemocytes and fat body of larvae infected with two entomopathogenic viruses with different lifestyles, i.e. the polydnavirus HdIV (Hyposoter didymator IchnoVirus) and the densovirus JcDV (Junonia coenia densovirus). We identified 1883 candidate lncRNAs, of which 529 showed differential expression following viral infection. Expression profiles differed considerably between samples, indicating that many differentially expressed (DE) lncRNAs showed virus- and tissue-specific expression patterns. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment and target prediction analyses indicated that DE-LncRNAs were mainly enriched in metabolic process, DNA replication and repair, immune response, metabolism of insect hormone and cell adhesion. In addition, we identified three DE-lncRNAs potentially acting as microRNA host genes, suggesting that they participate in gene regulation by producing miRNAs in response to virus infection. This study provides a catalogue of lncRNAs expressed in two important immune tissues and potential insight into their roles in the antiviral defence in S. frugiperda. The results may help future in-depth functional studies to better understand the biological function of lncRNAs in interaction between viruses and the fall armyworm.

Comprehensive Analysis of lncRNA and mRNA Expression Profile of Macrophage RAW264.7 Stimulated by Antimicrobial Peptide BSN-37

BACKGROUND

BSN-37, a novel antimicrobial peptide (AMP) containing 37 amino acid residues isolated from the bovine spleen, has not only antibacterial activity but also immunomodulatory activity. Recent evidence shows that long non-coding RNAs (lncRNAs) play an important role in regulating the activation and function of immune cells. The purpose of this experiment was to investigate the lncRNA and mRNA expression profile of mouse macrophages RAW264.7 stimulated by bovine antimicrobial peptide BSN-37.

METHODS

The whole gene expression microarray was used to detect the differentially expressed lncRNA and mRNA between antimicrobial peptide BSN-37 activated RAW264.7 cells and normal RAW264.7 cells. KEGG pathway analysis and GO function annotation analysis of differentially expressed lncRNAs and mRNA were carried out. Eight kinds of lncRNAs and nine kinds of mRNA with large differences were selected for qRT-PCR verification, respectively.

RESULTS

In the current study, we found that 1294 lncRNAs and 260 mRNAs were differentially expressed between antibacterial peptide BSN-37 treatment and control groups. Among them, Bcl2l12, Rab44, C1s, Cd101 and other genes were associated with immune responses and were all significantly up-regulated. Mest and Prkcz are related to cell growth, and other genes are related to glucose metabolism and lipid metabolism. In addition, some immune-related terms were also found in the GO and KEGG analyses. At the same time, real-time quantitative PCR was used to verify selected lncRNA and mRNA with differential expression. The results of qRT-PCR verification were consistent with the sequencing results, indicating that our data were reliable.

CONCLUSION

This study provides the lncRNA and mRNA expression profiles of RAW264.7 macrophages stimulated by antimicrobial peptide BSN-37 and helps to provide a reference value for subsequent studies on lncRNA regulation of antimicrobial peptide BSN-37 immune function.

Drosophila Relish Activating lncRNA-CR33942 Transcription Facilitates Antimicrobial Peptide Expression in Imd Innate Immune Response

Long noncoding RNAs (lncRNAs) are an emerging class of regulators that play crucial roles in regulating the strength and duration of innate immunity. However, little is known about the regulation of Drosophila innate immunity-related lncRNAs. In this study, we first revealed that overexpression of lncRNA-CR33942 could strengthen the expression of the Imd pathway antimicrobial peptide (AMP) genes Diptericin (Dpt) and Attacin-A (AttA) after infection, and vice versa. Secondly, RNA-seq analysis of lncRNA-CR33942-overexpressing flies post Gram-negative bacteria infection confirmed that lncRNA-CR33942 positively regulated the Drosophila immune deficiency (Imd) pathway. Mechanistically, we found that lncRNA-CR33942 interacts and enhances the binding of NF-κB transcription factor Relish to Dpt and AttA promoters, thereby facilitating Dpt and AttA expression. Relish could also directly promote lncRNA-CR33942 transcription by binding to its promoter. Finally, rescue experiments and dynamic expression profiling post-infection demonstrated the vital role of the Relish/lncRNA-CR33942/AMP regulatory axis in enhancing Imd pathway and maintaining immune homeostasis. Our study elucidates novel mechanistic insights into the role of lncRNA-CR33942 in activating Drosophila Imd pathway and the complex regulatory interaction during the innate immune response of animals.