Identification, structure and differential expression of novel pleurocidins clustered on the genome of the winter flounder, Pseudopleuronectes americanus (Walbaum)

Abstract

Antimicrobial peptides form one of the first lines of defense against invading pathogens by killing the microorganisms and/or mobilizing the host innate immune system. Although over 800 antimicrobial peptides have been isolated from many different species, especially insects, few have been reported from marine fish. Sequence analysis of two genomic clones (15.6 and 12.5 kb) from the winter flounder, Pseudopleuronectes americanus (Walbaum) resulted in the identification of multiple clustered genes for novel pleurocidin‐like antimicrobial peptides. Four genes and three pseudogenes (Ψ) are encoded in these clusters, all of which have similar intron/exon boundaries but specify putative antimicrobial peptides differing in sequence. Pseudogenes are easily detectable but have incorrect initiator codons (ACG) and often contain a frameshift(s). Potential promoters and binding sites for transcription factors implicated in regulation of expression of immune‐related genes have been identified in upstream regions by comparative genomics. Using reverse transcription‐PCR assays, we have shown for the first time that each gene is expressed in a tissue‐specific and developmental stage‐specific manner. In addition, synthetic peptides based on the sequences of both genes and pseudogenes have been produced and tested for antimicrobial activity. These data can be used as a basis for prediction of antimicrobial peptide candidates for both human and nonhuman therapeutants from genomic sequences and will aid in understanding the evolution and transcriptional regulation of expression of these peptides.

Anti-lipopolysaccharide factors from the black tiger shrimp, Penaeus monodon, are encoded by two genomic loci

“…Seven and five putative GATA sites are found in the ALF group A and B genes, respectively. The activator protein 1 (AP-1) factor is involved in the cell proliferation and survival [35], and also produced in response to viral infection [36]. The GAAA motif is recognized by interferon regulatory factor 1 (IRF-1) upon transcriptional activation of interferon-stimulated genes in virus-infected mammal cells [37].…”

“…The GAAA motif has also been shown to cooperate with the NF-kappaB motif in the LPSinduced expression of diptericin [38]. The Octamer-binding site 1 (Oct-1) is often found in the enhancer, and promotes the transcription of immune-relevant genes [36]. The putative Oct-1 sites are found in the P. monodon ALF genes.…”

Antimicrobial Peptides Are Expressed during Early Development of Zebrafish (Danio rerio) and Are Inducible by Immune Challenge

“…To date, more than 2400 AMPs have been reported in the Antimicrobial Peptide Database (http://aps.unmc.edu/AP/main.php), and they exhibit remarkable sequence diversity [5] indicating a sort of specification for microorganisms. The ability of AMPs to protect fish against infections by potential pathogens has been investigated in the last two decades [6][7][8][9][10][11][12][13]. For example, parasin I is abundant in fish mucus, and is produced from a precursor molecule, the histone H2A by the enzymatic action of cathepsin D [14].…”

Molecular characterization of hepcidin gene from mud loach (Misgurnus mizolepis; Cypriniformes)

“…The basal expression of hamp1 transcripts was also relatively greater in muscle, testis, and spleen than in the other tissues. The tissue distribution patterns of hepcidin transcripts under non-stimulated conditions differ according to the fish species and the hepcidin isoform, although most postmortem studies have reported liverpredominant expression [7,19,20,31].…”