Functional conservation and division of two single-carbohydrate-recognition domain C-type lectins from the nipa palm hispid beetle Octodonta nipae (Maulik). (November 2019)

• Record Type: Journal Article
• Authors: Zhang, Hua-Jian; Lin, Ya-Ping; Liu, Min; Liang, Xin-Yu; Ji, Ya-Nan; Tang, Bao-Zhen; Hou, You-Ming
• Is Part Of: Developmental and comparative immunology. Volume 100(2019)
• Publication Date: 2019-11
• Subjects: Octodonta nipae -- C-type lectin -- Phagocytosis -- Encapsulation -- Prophenoloxidase; C-type lecyin CTL -- carbohydrate-recogintion domain CRD -- C-type-lectin-like domain CTLD -- containing one CRD and other functional domains CTL-X -- single-CRD CTL-S -- the immune lectin group dual-CRD -- prophenoloxidase-activating factors PPAFs -- pathogen-associated molecular patterns PAMPs -- pattern-recognition receptors PRRs -- L-3, 4-dihydroxyphenylalanine l-DOPA -- ribosomal protein S3 rpS3 -- glyceraldehyde-3-phosphate dehydrogenase GAPDH -- phosphate buffered saline PBS -- antimicrobial peptide AMP -- encapsulation index EI; Immunology -- Periodicals; Developmental immunology -- Periodicals; 616.079
• DOI: 10.1016/j.dci.2019.103416
• Languages: English
• ISSNs: 0145-305X

Abstract

Abstract: As an invasive pest, the complete and effective innate immune system is crucial for the nipa palm hispid beetle Octodonta nipae (Maulik) to adjust to new environments. C-type lectins (CTLs) are large families of carbohydrate-binding proteins that possess one or more characteristic carbohydrate-recognition domains (CRD) and function as pattern-recognition receptors, which play important roles in mediating humoral and cellular immunity. In the present study, for the first time, we report two CTL-Ss (single-CRD CTLs) from O. nipae (Maulik) (designated OnCTL1 and OnCTL2). The two CTL-Ss share high identity at conserved amino acids associated with conserved carbohydrate binding sites Gln-Pro-Asp (QPD) motifs and clearly show a 1:1 orthologous relationship in insects, which endow them with functional conservation and diversification. mRNA abundance analysis showed that OnCTL1 was upregulated upon Staphylococcus aureus and Escherichia coli challenge at 6 and 12 h, while OnCTL2 underwent no changes upon E. coli challenge and was even downregulated after S. aureus infection. Knockdown of OnCTL1 significantly decreased the transcripts of two key serine proteases (prophenoloxidase activating factors), OnPPAF1 and OnPPAF3, followed by the reduction of haemolymph phenoloxidase activity; it also increased the expression of Defensin 2B . In contrast, silencing of OnCTL2 significantly decreased the expression of Defensin 2B and Attacin 3C, the encapsulation index, and the phagocytosis rate compared to the ds EGFP group. The spreading results showed that more irregularly shaped plasmatocytes and lower levels of aggregation were found in OnCTL2 -silenced pupae than in the ds OnCTL1 and ds EGFP groups. We can infer from the results of this study that the two OnCTLs play important roles in the immune system and generate a functional division: OnCTL1 seems to function more in humoral immunity including mediating bacterial recognition and activating the phenoloxidase cascade, and OnCTL2 plays a greater role in enhancing cellular immunity. These observations could replenish information on the functional diversification of insect CTLs, and also provide valuable information to unravel the immunity in O. nipae . Highlights: Two single-CRD C-type lectins from Octodonta nipae have functional division. OnCTL1 is more functional as a PRR in mediating bacterial recognition. OnCTL1 plays an important role in activating the phenoloxidase cascade. OnCTL2 plays a greater role in enhancing cellular immunity.