Molecular characterization and functional analysis of two distinct liver-expressed antimicrobial peptide 2 (LEAP-2) genes in large yellow croaker (Larimichthys crocea)

• Published in: Fish & shellfish immunology 2014-06, Vol.38 (2), p.330-339
• Main Authors: Li, He-Xiang, Lu, Xin-Jiang, Li, Chang-Hong, Chen, Jiong
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Antimicrobial activity; Bacterial load; Fish Proteins - chemistry; Fish Proteins - genetics; Fish Proteins - metabolism; Hepcidins - chemistry; Hepcidins - genetics; Hepcidins - metabolism; Large yellow croaker; Liver-expressed antimicrobial peptide 2; Molecular Sequence Data; Perciformes - genetics; Perciformes - immunology; Perciformes - metabolism; Phylogeny; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Alignment - veterinary; Survival rate; Vibrio alginolyticus; Vibrio alginolyticus - physiology
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2014.04.004

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. •We characterized two distinct LEAP-2 isoforms from large yellow croaker.•Tissue LcLEAP-2 transcripts were altered upon Vibrio alginolyticus infection.•LcLEAP-2C, but not LcLEAP-2A, had an antimicrobial activity against V. alginolyticus.•LcLEAP-2C enhanced survival in V. alginolyticus infected large yellow croaker.