Characterization and expression of non‐polymorphic liver expressed antimicrobial peptide 2: LEAP‐2 in the Japanese quail, Coturnix japonica

Abstract

Liver-expressed antimicrobial peptide 2 (LEAP-2) is a cationic peptide that plays an important role in innate immunity for host defense. The aim of this study was to characterize the LEAP-2 gene in the Japanese quail (Coturnix japonica). Japanese quail LEAP-2 (CjLEAP-2) was identified from the Japanese quail draft genome database by a local BLAST analysis using chicken LEAP-2 (GgLEAP-2). The exon-intron structure of CjLEAP-2, analyzed from three quails, is composed of three exons, as is the chicken LEAP-2 homolog (GgLEAP-2). An analysis of the coding sequence revealed that CjLEAP-2 is 231 bp long, like GgLEAP-2, and 93% identical to GgLEAP-2 at the nucleic acid level. The predicted amino acid sequence of CjLEAP-2 contained the liver-expressed antimicrobial peptide 2-precursor domain and four cysteine residues characteristic of the LEAP-2 protein. The amino acid sequence of the mature peptide of CjLEAP-2 was 100% identical to that of GgLEAP-2. We confirmed that CjLEAP-2 was transcribed in at least seven tissues, including the digestive system. Additionally, the mature peptide region of CjLEAP-2 exhibited no polymorphisms in 99 quails from six strains. Taken together, these findings indicate that CjLEAP-2 is non-polymorphic and therefore, it likely plays an important role in the innate immunity of quail as it does in chicken.

Identification of duck liver-expressed antimicrobial peptide 2 and characterization of its bactericidal activity

“…AMPs of animals are potentially powerful antibiotics substitutes. LEAP-2 is a generally well-known AMPs in mammals, avian, and fish that has bactericidal effects [12,15,17,18,20].…”

“…In most species, LEAP-2 is a cysteine-rich and cationic protein [14,15], which generally has a conserved core structure with two disulfide bonds that play a crucial role in bacterial killing [16]. In poultry, LEAP-2 sequences have been characterized in chicken and Japanese quail [17,18], but duck LEAP-2 has not yet been characterized.…”

Characterization of the cathelicidin cluster in the Japanese quail (Coturnix japonica)

“…Genomic DNA was isolated from the peripheral red blood cells using a DNeasy blood and tissue kit according to the manufacturer's protocol (Qiagen, Hilden, Germany). The SV total RNA Isolation System (Promega, Madison, WI, USA) was used to isolate total RNA from each of 20 different tissues, including bone marrow, thymus, BF, spleen, tongue, esophagus and crop, glandular stomach, gizzard, duodenum, jejunum, ileum, cecum, colon, pancreas, kidney, liver, trachea, lung, heart and testis dissected from one healthy 3‐week‐old male quail (Ishige et al ). For each of the 20 tissue types, the Rever Tra Ace ‐ α ‐ First Strand complementary DNA (cDNA) Synthesis Kit and random primers (Toyobo, Osaka, Japan) were used to synthesize cDNA from 1 μg of total RNA.…”

“…Host defense peptides (HDPs) are a diverse group of peptides and are known to play an important role in the innate immune systems of a wide range of organisms, from microorganisms to mammals. Several types of HPDs have been found in birds, such as NK-lysin (Cuperus et al 2013;Ishige et al 2014), cathelicidin (CATH; Cuperus et al 2013), liver-expressed antimicrobial peptide 2 (Cuperus et al 2013;Ishige et al 2016a), and β-defensin (Cuperus et al 2013;Ishige et al 2016b).…”

Host defence peptide LEAP2 contributes to antimicrobial activity in a mustache toad (Leptobrachium liui)

“…LEAP2 has been shown to destroy a variety of pathogenic microorganisms, including Bacillus megaterium, Bacillus subtilis, Neisseria cinerea, and Micrococcus luteus (Hocquellet et al, 2010;Krause et al, 2003). Besides mammals, LEAP2 has been identi ed in different species of birds (Ishige et al, 2016), reptiles (van Hoek, 2014), and even sh (Chen et al, 2016;Liu et al, 2020).…”