AUTHOR=Yang Wen-Jia , Chen Chun-Xu , Yan Yi , Xu Kang-Kang , Li Can 

TITLE=Clip-Domain Serine Protease Gene (LsCLIP3) Is Essential for Larval–Pupal Molting and Immunity in Lasioderma serricorne

JOURNAL=Frontiers in Physiology

VOLUME=10

YEAR=2020

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2019.01631

DOI=10.3389/fphys.2019.01631

ISSN=1664-042X

ABSTRACT=<p>Clip-domain serine proteases (CLIPs) play crucial roles in insect development and innate immunity. In this study, we identified a CLIP gene (designated <italic>Ls</italic>CLIP3) from the cigarette beetle <italic>Lasioderma serricorne</italic>. <italic>Ls</italic>CLIP3 contains a 1,773-bp open reading frame (ORF) encoding a 390-amino-acid protein and shows a conserved clip domain and a trypsin-like serine protease domain. Phylogenetic analysis indicated that <italic>Ls</italic>CLIP3 was orthologous to the CLIP-B subfamily. <italic>Ls</italic>CLIP3 was prominently expressed in larva, pupa, and early adult stages. In larval tissues, it was highly expressed in the integument and fat body. The expression of <italic>Ls</italic>CLIP3 was induced by 20-hydroxyecdysone. A similar induction was also found by peptidoglycans from <italic>Escherichia coli</italic> and <italic>Staphylococcus aureus</italic>. RNA interference (RNAi)-mediated silencing of <italic>Ls</italic>CLIP3 disrupted larval–pupal molting and specifically reduced the expression of genes in 20-hydroxyecdysone synthesis and signaling pathway. The chitin amounts of <italic>Ls</italic>CLIP3 RNAi larvae were greatly decreased, and expressions of six chitin metabolic-related genes were significantly reduced. Knockdown of <italic>Ls</italic>CLIP3 increased larval sensitivity to Gram-negative and Gram-positive bacteria. There was significantly decreased expression of four antimicrobial peptide (AMP) genes. The results suggest that <italic>Ls</italic>CLIP3 is an important component of the larva to pupa molt and for the immunity of <italic>L. serricorne</italic>.</p>