Critical Roles of Spätzle5 in Antimicrobial Peptide Production Against Escherichia coli in Tenebrio molitor Malpighian Tubules

• Published in: Frontiers in immunology 2021-12, Vol.12, p.760475-760475
• Main Authors: Ali Mohammadie Kojour, Maryam, Edosa, Tariku Tesfaye, Jang, Ho Am, Keshavarz, Maryam, Jo, Yong Hun, Han, Yeon Soo
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; antimicrobial peptides; Antimicrobial Peptides - genetics; Antimicrobial Peptides - immunology; Base Sequence; Candida albicans; Candidiasis - genetics; Candidiasis - immunology; Escherichia coli Infections - genetics; Escherichia coli Infections - immunology; Gene Silencing; Immunology; innate immune response; Insect Proteins - genetics; Insect Proteins - immunology; Malpighian Tubules - immunology; Malpighian Tubules - microbiology; NF-κB; spätzle 5; Staphylococcal Infections - genetics; Staphylococcal Infections - immunology; Staphylococcus aureus; Tenebrio - immunology; Tenebrio - microbiology; Tenebrio molitor; Toll signaling pathway; Transcription Factors - genetics
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2021.760475

The dimeric cytokine ligand Spätzle (Spz) is responsible for Toll pathway activation and antimicrobial peptide (AMP) production upon pathogen challenge in . Here, we indicated that Spz5 has a functional role in response to bacterial infections. We showed that the highest expression of is induced by . However, knockdown reduced larval survival against and . To evaluate the molecular mechanism underlying the observed survival differences, the role of in AMP production was examined by RNA interference and microbial injection. AMPs that are active against Gram-negative and -positive bacteria, including tenecins, attacins, coleoptericins, taumatin-like-proteins, and cecropin-2, were significantly downregulated by RNAi in the Malpighian tubules (MTs) following a challenge with and . However, upon infection with the mRNA levels of most AMPs in the ds -injected group were similar to those in the control groups. Likewise, the expression of the transcription factors NF-κB, , and were noticeably suppressed in the MTs of -silenced larvae. Moreover, -infected knockdown larvae showed decreased antimicrobial activity in the MTs and hindgut compared with the control group. These results demonstrate that Spz5 has a defined role in innate immunity by regulating AMP expression in MTs in response to .