Cloning and characterization of two lipopolysaccharide-binding protein/bactericidal permeability–increasing protein (LBP/BPI) genes from the sea cucumber Apostichopus japonicus with diversified function in modulating ROS production

• Published in: Developmental and comparative immunology Vol. 52; no. 1; pp. 88 - 97
• Main Authors: Shao, Yina, Li, Chenghua, Che, Zhongjie, Zhang, Pengjuan, Zhang, Weiwei, Duan, Xuemei, Li, Ye
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.09.2015
• Subjects: Acute-Phase Proteins - genetics; Acute-Phase Proteins - metabolism; Animals; Apostichopus japonicus; Base Sequence; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cloning, Molecular; Gene Knockdown Techniques; Humans; Immunity, Innate; Lipopolysaccharide-binding protein/bactericidal permeability–increasing protein; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Molecular Sequence Data; Phylogeny; Protein Isoforms - genetics; Protein Isoforms - metabolism; Reactive Oxygen Species - metabolism; Respiratory burst; RNA interference; Sea Cucumbers - physiology; Signal Transduction; Toll like receptor; Vibrio - immunology; Vibrio Infections - immunology; Toll like receptor; RNA interference; Respiratory burst; Apostichopus japonicus; Lipopolysaccharide-binding protein/bactericidal permeability–increasing protein
• ISSN: 0145-305X; 1879-0089
• DOI: 10.1016/j.dci.2015.04.015

•Two isoforms of AjLBP/BPIs were identified in Apostichopus japonicus.•AjLBP/BPI1 and AjLBP/BPI2 were ubiquitously expressed in all examined tissues.•ROS production was markedly depressed after AjLBP/BPI1, not AjLBP/BPI2 knock-down.•The expression level of AjToll, not AjTLR3, was tightly correlated with AjLBP/BPI1 expression.•Silencing the AjToll also depressed the ROS production in the cultured coelomocytes. Lipopolysaccharide-binding protein and bactericidal permeability–increasing protein (LBP/BPI) play crucial role in modulating cellular signals in response to Gram-negative bacteria infection. In the present study, two isoforms of LBP/BPI genes (designated as AjLBP/BPI1 and AjLBP/BPI2, respectively) were cloned from the sea cucumber Apostichopus japonicus by RACE approach. The full-length cDNAs of AjLBP/BPI1 and AjLBP/BPI2 were of 1479 and 1455 bp and encoded two secreted proteins of 492 and 484 amino acid residues, respectively. Signal peptide, two BPI/LBP/CETP and one central domain were totally conserved in the deduced amino acid of AjLBP/BPI1 and AjLBP/BPI2. Phylogentic analysis further supported that AjLBP/BPI1 and AjLBP/BPI2 belonged to new members of invertebrates LBP/BPI family. Spatial expression analysis revealed that both AjLBP/BPI1 and AjLBP/BPI2 were ubiquitously expressed in all examined tissues with the larger magnitude in AjLBP/BPI1. The Vibrio splenfidus challenge and LPS stimulation could significantly up-regulate the mRNA expression of both AjLBP/BPI1 and AjLBP/BPI2, with the increase of AjLBP/BPI2 expression occurred earlier than that of AjLBP/BPI1. More importantly, we found that LPS induced ROS production was markedly depressed after AjLBP/BPI1 knock-down, but there was no significant change by AjLBP/BPI2 silencing. Consistently, the expression level of unclassified AjToll, not AjTLR3, was tightly correlated with that of AjLBP/BPI1. Silencing the AjToll also depressed the ROS production in the cultured coelomocytes. All these results indicated that AjLBP/BPI1 and AjLBP/BPI2 probably played distinct roles in bacterial mediating immune response in sea cucumber, and AjLBP/BPI1 depressed coelomocytes ROS production via modulating AjToll cascade.