title: Molecular cloning and characterization of rat genes encoding homologues of human beta-defensins.
abstract: beta-Defensins are cationic peptides with broad-spectrum antimicrobial activity that may play a role in mucosal defenses of several organs. They have been isolated in several species, and in humans, two beta-defensins have been identified. Here, we report the identification of two genes encoding beta-defensin homologues in the rat. Partial cDNAs were found by searching the expressed-sequence-tag database, and primers were designed to generate full-length mRNA coding sequences. One gene was highly similar to the human beta-defensin-1 (HBD-1) gene and mouse beta-defensin-1 gene at both the nucleic acid and amino acid levels and was termed rat beta-defensin-1 (RBD-1). The other gene, named RBD-2, was homologous to the HBD-2 and bovine tracheal antimicrobial peptide (TAP) genes. The predicted prepropeptides were strongly cationic, were 69 and 63 residues in length for RBD-1 and RBD-2, respectively, and contained the six-cysteine motif characteristic of beta-defensins. The beta-defensin genes mapped closely on rat chromosome 16 and were closely linked to the alpha-defensins genes, suggesting that they are part of a gene cluster, similar to the organization reported for humans. Northern blot analysis showed that both RBD-1 and RBD-2 mRNA transcripts were approximately 0.5 kb in length; RBD-1 mRNA was abundantly transcribed in the rat kidney, while RBD-2 was prevalent in the lung. Reverse transcription-PCR indicated that RBD-1 and RBD-2 mRNAs were distributed in a variety of other tissues. In the lung, RBD-1 mRNA expression localized to the tracheal epithelium while RBD-2 was expressed in alveolar type II cells. In conclusion, we characterized two novel beta-defensin homologues in the rat. The rat may be a useful model to investigate the function and contribution of beta-defensins to host defense in the lung, kidney, and other tissues.
authors.affiliation: Department of Pediatrics, University of Iowa College of Medicine, Iowa City, Iowa, USA.
authors.forename: H P
authors.initials: HP
authors.lastname: Jia
authors.forename: J N
authors.initials: JN
authors.lastname: Mills
authors.forename: F
authors.initials: F
authors.lastname: Barahmand-Pour
authors.forename: D
authors.initials: D
authors.lastname: Nishimura
authors.forename: R K
authors.initials: RK
authors.lastname: Mallampali
authors.forename: G
authors.initials: G
authors.lastname: Wang
authors.forename: K
authors.initials: K
authors.lastname: Wiles
authors.forename: B F
authors.initials: BF
authors.lastname: Tack
authors.forename: C L
authors.initials: CL
authors.lastname: Bevins
authors.forename: P B
authors.initials: PB
authors.lastname: McCray
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D001992:Bronchoalveolar Lavage Fluid; D002417:Cattle; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018076:DNA, Complementary; D023082:Defensins; D015870:Gene Expression; D006801:Humans; D017403:In Situ Hybridization; D051379:Mice; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger; D051381:Rats; D017207:Rats, Sprague-Dawley; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride; D014018:Tissue Distribution; D023083:beta-Defensins
chemical_list: C406407:DEFB1 protein, human; D018076:DNA, Complementary; D023082:Defensins; D011506:Proteins; D012333:RNA, Messenger; D023083:beta-Defensins; D012965:Sodium Chloride