TmSpz4 Plays an Important Role in Regulating the Production of Antimicrobial Peptides in Response to Escherichia coli and Candida albicans Infections

Patnaik

Kojour

et al. 2021

IJMS

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The cystine knot protein Spätzle is a Toll receptor ligand that modulates the intracellular signaling cascade involved in the nuclear factor kappa B (NF-κB)-mediated regulation of antimicrobial peptide (AMP)-encoding genes. Spätzle-mediated activation of the Toll pathway is critical for the innate immune responses of insects against Gram-positive bacteria and fungi. In this study, the open reading frame (ORF) sequence of Spätzle-like from T. molitor (TmSpz-like) identified from the RNA sequencing dataset was cloned and sequenced. The 885-bp TmSpz-like ORF encoded a polypeptide of 294 amino acid residues. TmSpz-like comprised a cystine knot domain with six conserved cysteine residues that formed three disulfide bonds. Additionally, TmSpz-like exhibited the highest amino acid sequence similarity with T. castaneum Spätzle (TcSpz). In the phylogenetic tree, TmSpz-like and TcSpz were located within a single cluster. The expression of TmSpz-like was upregulated in the Malpighian tubules and gut tissues of T. molitor. Additionally, the expression of TmSpz-like in the whole body and gut of the larvae was upregulated at 24 h post-E. coli infection. The results of RNA interference experiments revealed that TmSpz-like is critical for the viability of E. coli-infected T. molitor larvae. Eleven AMP-encoding genes were downregulated in the E. coli-infected TmSpz-like knockdown larvae, which suggested that TmSpz-like positively regulated these genes. Additionally, the NF-κB-encoding genes (TmDorX1, TmDorX2, and TmRelish) were downregulated in the E. coli-infected TmSpz-like knockdown larvae. Thus, TmSpz-like plays a critical role in the regulation of AMP production in T. molitor in response to E. coli infection.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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TmSpz-like Plays a Fundamental Role in Response to E. coli but Not S. aureus or C. albican Infection in Tenebrio molitor via Regulation of Antimicrobial Peptide Production

Patnaik

Kojour

et al. 2021

IJMS

Self Cite

“…Genetic analyses of the mealworm beetle, Tenebrio molitor ( T. molitor ) , have demonstrated similar fundamental mechanisms (Edosa et al . 2020a; Edosa et al . 2020b; Keshavarz et al .…”

Section: Introductionmentioning

confidence: 99%

Identification, in silico characterization, and expression analysis of Tenebrio molitor Cecropin‐2

Kojour

Edosa

et al. 2020

Entomological Research

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Antimicrobial peptides (AMPs) are considered to be candidate effectors for eliciting humoral immune responses against infectious pathogens in the host. Cecropins are α‐helical peptides of 30–40 amino acids, which are known to permeabilize bacterial membranes, and play authoritative roles in the innate immune system of insects. In the present study, we identified the full‐length open reading frame (ORF) encoding the Tenebrio molitor cecropin‐2 (TmCec2) gene using the Tribolium castaneum cecropin‐2 (TcCec2) gene to query a T. molitor Rnaseq database. Phylogenetic analysis revealed close identity of TmCec2 with TcCec2. TmCec2 was ubiquitously expressed in the insect during all developmental stages, with the highest expression observed in the adult. Tissue‐specific TmCec2 expression was highest in larval hemocytes and in the adult integument and hemocytes. Microbial challenge experiments revealed that TmCec2 was highly induced in response to gram‐positive and gram‐negative bacteria, and fungi. These data provide credible evidence for a putative role of TmCec2 in insect innate immunity against a plethora of pathogens.

“…TmDefensin‐1 and − 2 , have been used in our previous studies (Edosa et al . 2020a,b; Jo et al . 2017, 2019; Keshavarz et al .…”

Section: Introductionmentioning

confidence: 99%

In silico identification and expression analyses of Defensin genes in the mealworm beetle Tenebrio molitor

Park

Kim

et al. 2020

Entomological Research

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Defensins are a major family of antimicrobial peptides that serve as the innate immune defense of both vertebrates and invertebrates. Due to their antimicrobial, chemotactic, and regulatory activities, Defensins have been exploited for their therapeutic potential. Insect Defensins are cysteine-rich and contain an N-terminal loop, α-helix, and antiparallel β-sheet, forming a "cysteine-stabilized alpha beta (CSαβ)" or "loop-helix-sheet" structure. In this study, we identified the full-length open reading frame (ORF) sequences of Defensin (TmDef) and Defensin-like (TmDef-like) genes from the mealworm beetle Tenebrio molitor using in silico methods. TmDef and TmDef-like genes encode the peptides of 72 and 71 amino acid residues, respectively. TmDefensin is comprised of a Defensin domain and the TmDefensin-like is comprised of a signal peptide of 21 amino acid residues. Phylogenetic analysis revealed close similarities of TmDefensin with the Defensin of Acalolepta luxuriosa of the longhorn beetle family. The expression of TmDef mRNA was found to be greater than that of TmDef-like mRNA and was mostly expressed in the pupal and adult stages. Tissue distribution showed high expression of TmDef-like mRNA in larval hemocytes, gut, integument, and fat body, while in adults, the expression was high in gut and hemocytes. Following bacterial and fungal stimulation in vivo, TmDef was upregulated at 24 h post-infection in whole body, fat body, and hemocytes of the larvae. Even TmDef-like mRNA was upregulated in the gut and hemocytes at 12 and 9 h post-infection respectively. These results suggest that TmDef and TmDef-like genes play important roles in protecting T. molitor from microbial contact.