title: Molecular characterization and functional analysis of two distinct liver-expressed antimicrobial peptide 2 (LEAP-2) genes in large yellow croaker (Larimichthys crocea).
abstract: Liver-expressed antimicrobial peptide 2 (LEAP-2) plays a vital role in the host innate immune system. In the present study, two LEAP-2 genes (LcLEAP-2A and LcLEAP-2C) from large yellow croaker (Larimichthys crocea) were cloned, both of which consist of 3 exons and 2 introns. The LcLEAP-2A transcripts were expressed in a wide range of tissues, with the highest mRNA levels found in the liver and intestine, while LcLEAP-2C transcripts showed obvious lower mRNA levels in all tested tissues compared to LcLEAP-2A. Upon infection by Vibrio alginolyticus, LcLEAP-2A transcripts were significantly up-regulated in liver, trunk kidney, spleen, head kidney, and gill, but down-regulated in intestine. In addition, significant up-regulation of LcLEAP-2C transcripts were also detected in all tissues tested, including intestine. The LcLEAP-2A and LcLEAP-2C mature peptides were chemically synthesized and found to exhibit selective antimicrobial activity in vitro against various species of bacteria. LcLEAP-2C, but not LcLEAP-2A, had antimicrobial activity against V. alginolyticus. Moreover, LcLEAP-2C treatment at low concentrations was evaluated and found to improve survival rate in V. alginolyticus-infected large yellow croaker, resulting in a decrease in bacterial load and expression of inflammatory cytokines. These results suggest that LcLEAP-2 isoforms play an important role in innate immunity by killing bacteria and inhibiting early inflammatory response in large yellow croaker.
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo 315211, China.
authors.forename: He-Xiang
authors.initials: HX
authors.lastname: Li
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo 315211, China.
authors.forename: Xin-Jiang
authors.initials: XJ
authors.lastname: Lu
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo 315211, China.
authors.forename: Chang-Hong
authors.initials: CH
authors.lastname: Li
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo 315211, China. Electronic address: jchen1975@163.com.
authors.forename: Jiong
authors.initials: J
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D064451:Hepcidins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment / Q000662:veterinary; D044149:Vibrio alginolyticus / Q000502:physiology
chemical_list: D029941:Fish Proteins; D064451:Hepcidins; D012333:RNA, Messenger
keywords: Antimicrobial activity; Bacterial load; Large yellow croaker; Liver-expressed antimicrobial peptide 2; Survival rate