A pattern recognition receptor C‐type lectin TcCTL14 contributes to immune response and development in the red flour beetle, Tribolium castaneum

Abstract

Evidence is accumulating that pattern recognition receptor (PRR) C‐type lectins (CTL) play essential roles in recognition of pathogens. TcCTL14 (accession no. TC00871) contains the most domains among all CTL of Tribolium castaneum. Yet the biological function of TcCTL14 remains unclear. In this study, TcCTL14 exhibiting typical motif and domain of CTL was cloned from T. castaneum. The expression pattern analysis showed that TcCTL14 was highly expressed in late pupae and central nervous system, and was upregulated after treatment with Escherichia coli and Staphylococcus aureus, respectively. Analysis of binding affinity revealed that recombinant TcCTL14 not only could bind to lipopolysaccharide and peptidoglycan in a dose‐dependent fashion, but possibly could bind to and agglutinate different bacteria in a Ca2+‐dependent fashion. Knockdown of TcCTL14 before injection with bacteria led to the downregulation of nuclear factor‐κB transcription factors of Toll/IMD and 4 antimicrobial peptides. Knockdown of TcCTL14 also caused suppressed metamorphosis, reduced fecundity, and delayed embryogenesis of T. castaneum. Further observation discovered that knockdown of TcCTL14 inhibited the development of ovaries and embryos. The detection of signaling pathways revealed that TcCTL14 may be involved in metamorphosis and fecundity by impacting 20‐hydroxyecdysone and vitellogenin, respectively. Overall, these results indicate that TcCTL14 may contribute to immune response by agglutination or regulating the expression of antimicrobial peptides by the Toll/IMD pathway, and is required for T. castaneum development including metamorphosis, fecundity, and embryogenesis. These findings will improve the functional cognition of PRR CTL in insects and provide the new strategy for pest control.

Genome‐wide CRISPR screening reveals key genes and pathways associated with 20‐hydroxyecdysone signal transduction in the silkworm (Bombyx mori)

“…, 2018; Zhang et al. , 2022), we found that the depleted genes were mainly involved in the Toll pathway and the enriched genes were mainly associated with the Imd pathway (Fig. 4B).…”

“…4C, D). Through literature and database review (Chen et al, 2008;Govind, 2008;Hua et al, 2016;Yang et al, 2018;Zhang et al, 2022), we found that the depleted genes were mainly involved in the Toll pathway and the enriched genes were mainly associated with the Imd pathway (Fig. 4B).…”

The glutathione biosynthesis is involved in metamorphosis, antioxidant function, and insecticide resistance in Tribolium castaneum

“…Double‐stranded RNA synthesis, injection, and behavior analysis were performed in accordance with the procedure described in a previous study 22 . Briefly, PCR products produced by dsTcGclc primers, including gene‐specific sequences, and T7 polymerase promoter were purified using a gel purification kit (product code: DC301; Vazyme).…”

“…20,21 2.6 RNAi and behavioral analysis Double-stranded RNA synthesis, injection, and behavior analysis were performed in accordance with the procedure described in a previous study. 22 Briefly, PCR products produced by dsTcGclc primers, including gene-specific sequences, and T7 polymerase promoter were purified using a gel purification kit (product code: DC301; Vazyme). This purified PCR product was used as the template to synthesize dsRNA with a TranscriptAid T7 high-yield transcription kit (product code: K0441; Thermo Fisher Scientific, Shanghai, China).…”