IKKγ/NEMO Is Required to Confer Antimicrobial Innate Immune Responses in the Yellow Mealworm, .

IKK/NEMO is the regulatory subunit of the IκB kinase (IKK) complex, which regulates the NF-κB signaling pathway. Within the IKK complex, IKK/NEMO is the non-catalytic subunit, whereas IKK and IKK are the structurally related catalytic subunits. In this study, was screened from the RNA-Seq database and functionally characterized using RNAi screening for its role in regulating antimicrobial peptide (AMP) genes after microbial challenges. The transcript is 1521 bp that putatively encodes a polypeptide of 506 amino acid residues. IKKγ contains a NF-κB essential modulator (NEMO) and a leucine zipper domain of coiled coil region 2 (LZCC2). A phylogenetic analysis confirmed its homology to the red flour beetle, IKKγ (IKKγ). The expression of mRNA showed that it might function in diverse tissues of the insect, with a higher expression in the hemocytes and the fat body of the late-instar larvae. mRNA expression was induced by , , and challenges in the whole larvae and in tissues such as the hemocytes, gut and fat body. The knockdown of mRNA significantly reduced the survival of the larvae after microbial challenges. Furthermore, we investigated the tissue-specific induction patterns of fourteen AMP genes in mRNA-silenced individuals after microbial challenges. In general, the mRNA expression of , , and ; and ; and ; and , , and were found to be downregulated in the hemocytes, gut, and fat body tissues in the silenced individuals after microbial challenges. Under similar conditions, (NF-κB transcription factor) mRNA was also found to be downregulated. Thus, is an important factor in the antimicrobial innate immune response of .