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

• Published in: International journal of molecular sciences 2020-03, Vol.21 (5), p.1878
• Main Authors: Edosa, Tariku Tesfaye, Jo, Yong Hun, Keshavarz, Maryam, Bae, Young Min, Kim, Dong Hyun, Lee, Yong Seok, Han, Yeon Soo
• Format: Article
• Language: English
• Subjects: amp expression; Antiinfectives and antibacterials; Antimicrobial peptides; Bacteria; Candida albicans; Cytokines; defense response; E coli; Enzymes; Escherichia coli; Fungi; Gene expression; Gram-negative bacteria; Gram-positive bacteria; Hemocytes; Immune response; Immune system; Infections; Insects; Larvae; Ligands; mealworm; Microorganisms; NF-κB protein; Pathogens; Peptides; Phylogenetics; Proteins; Signal transduction; spätzle; Staphylococcus aureus; Survivability; Tenebrio molitor; toll receptor
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms21051878

Spätzle family proteins activate the Toll pathway and induce antimicrobial peptide (AMP) production against microbial infections. However, the functional importance of Tmspätzle4 (TmSpz4) in the immune response of Tenebrio molitor has not been reported. Therefore, here, we have identified and functionally characterized the role of TmSpz4 against bacterial and fungal infections. We showed that TmSpz4 expression was significantly induced in hemocytes at 6 h post-injection with Escherichia coli, Staphylococcus aureus, and Candida albicans. TmSpz4 knock-down significantly reduced larval survival against E. coli and C. albicans. To understand the reason for the survivability difference, the role of TmSpz4 in AMP production was examined in TmSpz4-silenced larvae following microbe injection. The AMPs that are active against Gram-negative bacteria, including TmTenecin-2, TmTenecin-4, TmAttacin-1a, TmDefensin-2, and TmCecropin-2, were significantly downregulated in response to E. coli in TmSpz4-silenced larvae. Similarly, the expression of TmTenecin-1, TmTenecin-3, TmThaumatin-like protein-1 and -2, TmDefensin-1, TmDefensin-2, and TmCecropin-2 were downregulated in response to C. albicans in TmSpz4-silenced larvae. In addition, the transcription factor NF-κB (TmDorX1 and TmDorX2) expression was significantly suppression in TmSpz4-silenced larvae. In conclusion, these results suggest that TmSpz4 plays a key role in regulating immune responses of T. molitor against to E. coli and C. albicans.