Peptidoglycan recognition protein-S1 acts as a receptor to activate AMP expression through the IMD pathway in the silkworm Bombyx mori

Wang, Qiang; Wang, Jiayou; Ren, Meijia; Ma, Shangshang; Liu, Xiaoyong; Chen, Keping; Xia, Hengchuan

doi:10.1016/j.dci.2020.103903

Cited by 16 publications

(12 citation statements)

References 19 publications

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“…Previous studies have shown that pattern recognition proteins (PRPs) in insects activate immune pathways by binding to PAMPs ( 49 ). BmPGRP-S1 can be used as a pattern recognition protein to bind bacteria or PG and activate the IMD pathway to activate the production of AMPs ( 50 ). Our results showed that KPI5 can promoted AMP expression in the silkworm fat body.…”

Section: Discussionmentioning

confidence: 99%

KPI5 Is Involved in the Regulation of the Expression of Antibacterial Peptide Genes and Hemolymph Melanization in the Silkworm, Bombyx mori

Heng

Liu

et al. 2022

Front. Immunol.

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Kunitz-type protease inhibitors (KPIs) are ubiquitously found in many organisms, and participate in various physiological processes. However, their function in insects remains to be elucidated. In the present study, we characterized and functionally analyzed silkworm KPI5. Sequence analysis showed that KPI5 contains 85 amino acids with six conserved cysteine residues, and the P1 site is a phenylalanine residue. Inhibitory activity and stability analyses indicated that recombinant KPI5 protein significantly inhibited the activity of chymotrypsin and was highly tolerant to temperature and pH. The spatio-temporal expression profile analysis showed that KPI5 was synthesized in the fat body and secreted into the hemolymph. In vivo induction analysis showed that the expression of KPI5 in the fat body was significantly upregulated by pathogen-associated molecular patterns (PAMPs). Binding assays suggested that KPI5 can bind to pathogens and PAMPs. In vitro pathogen growth inhibition assay and encapsulation analysis indicated that KPI5 can neither kill pathogenic bacteria directly nor promote the encapsulation of agarose beads by silkworm hemocytes. Recombinant protein injection test and CRISPR/Cas9-mediated knockdown showed that KPI5 promotes the expression of antimicrobial peptides (AMPs) in the fat body. Moreover, the survival rate of individuals in the KPI5 knockdown group was significantly lower than that of the control group after pathogen infection. Phenoloxidase (PO) activity assays showed that KPI5 significantly inhibited the hemolymph PO activity and melanization induced by PAMPs. These findings suggested that KPI5 plays a dual regulatory role in innate immunity by promoting the expression of antimicrobial peptides in the fat body and inhibiting hemolymph melanization. Our study furthers the understanding of the function of insect KPIs and provides new insights into the regulatory mechanism of insect immune homeostasis.

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Section: Discussionmentioning

confidence: 99%

KPI5 Is Involved in the Regulation of the Expression of Antibacterial Peptide Genes and Hemolymph Melanization in the Silkworm, Bombyx mori

Heng

Liu

et al. 2022

Front. Immunol.

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“…There is no specification for considering any specific instar larva for the AMP collection. However, in a study, the lowest transcription level was observed during first-instar larval stages and the highest transcription level during the fifth-instar larval stage [52]. At the fifth stage, growth is completed, and metamorphosis is initiated [53].…”

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confidence: 92%

Harvesting of Antimicrobial Peptides from Insect (Hermetia illucens) and Its Applications in the Food Packaging

2021

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About one-third of the total food produced is wasted, rising the concern to adopt proper management. Simultaneously with the increase in population, demand for food is increasing which may lead to scarcity. Adequate packaging is one of the ways to avoid deterioration of food and prevent wastage. In recent years, active packaging has attained interest due to its commendable results in food preservation. Several studies proved that the embodiment of antimicrobial components into the packaging material has the ability to prevent microbial contamination. Antimicrobial peptides (AMP) are newly discovered antimicrobial agents for impregnation into packaging material. Among various sources for AMP, insects have shown great resistivity against a wide spectrum of microorganisms. Insects feed on substances consisting of a varying range of contaminations, which often results in infections. Insects synthesise AMPs to fight such infections and survive in that atmosphere. The disease-causing agents in humans are the same as those found in insects. Hence, AMPs extracted from insects have the potential to fight the microorganisms that act as hazards to human health. This review highlights the harvesting and synthesis of AMPs from Hermetia illucens, which is a promising source for AMP and its applications in the food packaging industry.

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“…16 N. bombycis infection of Bombyx mori larvae activates the JAK/STAT and Toll pathways in the midgut, which induces the up-regulation of the expression of innate immune-related defense proteins involved in humoral and cellular immunity, including moricins, lebocins and lysozymes, to resist invasion by microsporidia. [17][18][19][20] In addition, the production of the prophenoloxidase (PPO) by the gut epidermal cells of the silkworm is also suppressed after microsporidian infection due to the induction of melanization, thus preventing pathogens from entering the surrounding habitat. 1,21 Similar to most lepidopteran larvae, silkworm larvae possess a relatively simple gut without specialized substructures; however, a sufficient gut bacterial population exceeding 10 7 CFU/mL is clearly present.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, it is not surprising that silkworms have evolved effective anti‐ N. bombycis strategies, including its innate immune system as well as the chemical and physical barriers present in the gut, such as a strong alkaline digestion mechanism 16 . N. bombycis infection of Bombyx mori larvae activates the JAK/STAT and Toll pathways in the midgut, which induces the up‐regulation of the expression of innate immune‐related defense proteins involved in humoral and cellular immunity, including moricins, lebocins and lysozymes, to resist invasion by microsporidia 17–20 . In addition, the production of the prophenoloxidase (PPO) by the gut epidermal cells of the silkworm is also suppressed after microsporidian infection due to the induction of melanization, thus preventing pathogens from entering the surrounding habitat 1,21 …”

Section: Introductionmentioning

confidence: 99%

The gut commensal bacterium Enterococcus faecalis LX10 contributes to defending against Nosema bombycis infection in Bombyx mori

Zhang

Feng

et al. 2022

Pest Management Science

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BACKGROUND: Microsporidia, a group of obligate intracellular fungal-related parasites, have been used as efficient biocontrol agents for agriculture and forestry pests due to their host specificity and transovarial transmission. They mainly infect insect pests through the intestinal tract, but the interactions between microsporidia and the gut microbiota of the host have not been well demonstrated.RESULTS: Based on the microsporidia-Bombyx mori model, we report that the susceptibility of silkworms to exposure to the microsporidium Nosema bombycis was both dose and time dependent. Comparative analyses of the silkworm gut microbiome revealed substantially increased abundance of Enterococcus belonging to Firmicutes after N. bombycis infection. Furthermore, a bacterial strain (LX10) was obtained from the gut of B. mori and identified as Enterococcus faecalis based on 16S rRNA sequence analysis. E. faecalis LX10 reduced the N. bombycis spore germination rate and the infection efficiency in vitro and in vivo, as confirmed by bioassay tests and histopathological analyses. In addition, after simultaneous oral feeding with E. faecalis LX10 and N. bombycis, gene (Akirin, Cecropin A, Mesh, Ssk, DUOX and NOS) expression, hydrogen peroxide and nitric oxide levels, and glutathione S-transferase (GST) activity showed different degrees of recovery and correction compared with those under N. bombycis infection alone. Finally, the enterococcin LX protein was identified from sterile LX10 fermentation liquid based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis.CONCLUSION: Altogether, the results revealed that E. faecalis LX10 with anti-N. bombycis activity might play an important role in protecting silkworms from microsporidia. Removal of these specific commensal bacteria with antibiotics and utilization of transgenic symbiotic systems may effectively improve the biocontrol value of microsporidia.

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Peptidoglycan recognition protein-S1 acts as a receptor to activate AMP expression through the IMD pathway in the silkworm Bombyx mori

Cited by 16 publications

References 19 publications

KPI5 Is Involved in the Regulation of the Expression of Antibacterial Peptide Genes and Hemolymph Melanization in the Silkworm, Bombyx mori

KPI5 Is Involved in the Regulation of the Expression of Antibacterial Peptide Genes and Hemolymph Melanization in the Silkworm, Bombyx mori

Harvesting of Antimicrobial Peptides from Insect (Hermetia illucens) and Its Applications in the Food Packaging

The gut commensal bacterium Enterococcus faecalis LX10 contributes to defending against Nosema bombycis infection in Bombyx mori

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