Reindeer beta-defensin-1: full-length cDNA cloning and tissue expression

Defensins are members of a large diverse family of cationic antimicrobial peptides that share a signature pattern consisting of six conserved cysteine residues. Here we report the identification of a novel beta-defensin, reindeer beta-defensin-1 (reBD-1), from reindeer tissues with a pair PCR primers according to the conserved cDNA sequences of known ruminant beta-defensins. Total RNA was extracted from the tongue epithelia of a reindeer and the 372bp cDNA encoding reBD-1 was amplified by the reverse transcription PCR (RT-PCR), 5'- and 3'-RACE. The cDNA contained a open reading frame (ORF) of 192 bases which encoded a 64 amino acid prepro-peptide and the prepro-peptide contained the beta-defensin consensus sequence of six invariantly spaced cysteine residues. The sequence homology shows that reBD-1 has 68.8-87.5% amino-acid identity and 76.6-90.9% cDNA identity with other ruminant beta-defensins, sharing the greatest identity with buffalo enteric beta-defensin in both amino acid and nucleotide sequences. The reBD-1 mRNA was detected throughout the digestive tracts and also in trachea, lung, kidney, urinary bladder, testis, epididymis, heart, liver, spleen by RT-PCR. The wide expression of reBD-1 indicates that this endogenous peptide may contribute to both mucosal and systemic host defenses in reindeers.