Tissue- and age-dependent expression of the bovine DEFB103 gene and protein.

Beta-defensin 103 (DEFB103) shares little homology with 8 other members of the bovine beta-defensin family and in other species DEFB103 protein has diverse functions, including antimicrobial activity, a chemoattractant for dendritic cells, enhancing epithelial wound repair and regulating hair colour. Expression of the bovine DEFB103 gene was surveyed in 27 tissues and transcript was most abundant in tissues with stratified squamous epithelium. Oral cavity epithelial tissues and nictitating membrane consistently expressed high levels of DEFB103 gene transcript. An age-dependent decrease (P < 0.05) in DEFB103 gene expression was only observed for buccal epithelium when comparing healthy 10- to 14-day-old and 10- to 12-month-old calves. A bovine herpesvirus-1 respiratory infection did, however, significantly (P < 0.05) up-regulate DEFB103 gene expression in the buccal epithelium of 6- to 8-month-old calves. Finally, DEFB103 transcript was low in lymph nodes draining the skin and at the limit of detection in other internal organs such as lung, intestine and kidney. Affinity-purified rabbit antisera to bovine DEFB103 was used to identify cells expressing DEFB103 protein within tissues with stratified squamous epitheliums. DEFB103 protein was most abundant in basal epithelial cells and was present in these cells prior to birth. Beta-defensins have been identified as regulators of dendritic cell (DC) chemokine responses and we observed a close association between DCs and epithelial cells expressing DEFB103 in both the fetus and newborn calf. In conclusion, bovine DEFB103 gene expression is most abundant in stratified squamous epithelium with DEFB103 protein localised to basal epithelial cells. These observations are consistent with proposed roles for DEFB103 in DC recruitment and repair of stratified squamous epithelium.

Identification of a new non-coding exon and haplotype variability in the cattle DEFB103 gene.

The DEFB103 gene is a member of the ß-defensin gene family. In this study, we applied multiple sets of primers to characterize the DEFB103 transcript. RT-PCR was used to determine the cDNA boundaries and it indicated that the cDNA start point is at least 514 bp before the start codon and not further than 678 bp. In addition, the length of the 3'UTR was determined to be at least 53 bp after the stop codon. Seven SNPs were located in the 5'UTR, and comprised 4 different haplotypes in genomic DNA. Using these haplotype data, it could be proven that at least two complete copies of DEFB103 with an ATG start codon are present in cDNA in most cattle. Additionally haplotype data indicated that there are also multiple incomplete copies in most cattle. A non-coding exon 1a, and a 261 bp intron 1a were identified in cattle, and subsequently predicted in sheep and goats. DEFB103 sequence assemblies and partial cloning sequences revealed two types of deletion (4 bp and 8 bp) in the 5'UTR. These observations could prove that these copies are not assembly artifact.