Submitted to: Mammalian Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/1998
Publication Date: N/A
Interpretive Summary: Escherichia coli O157:H7 from beef sources has recently caused serious outbreaks resulting in human sickness and death. The aim of this study was to identify and map genes that are expressed in bovine cells in the early phases of E. coli O157:H7 infection. Bovine cell cultures were exposed to a toxin present on the E. coli O157:H7 envelope and changes in the cattle gene expression were observed. Two related cattle genes were discovered (IL-8 and ECIP-1) that were expressed in response to E. coli. The human counterparts for these genes are known to be induced by E. coli and proposed to aid in clearance of E. coli infections. Like the human gene counterparts, both cattle genes were mapped to a narrow region of one chromosome. This clustering of genes suggests conservation of these respective regions in the cattle and human genomes. Identifying, mapping, and comparing such genes are an important first step toward elucidating their role in the pathogenesis of bacterial infection in cattle.
Technical Abstract: RNA fingerprinting by arbitrarily primed (RAP)-PCR was used to identify two bovine genes that were differentially expressed in epithelial cells during inflammatory response. RNA fingerprints revealed two differentially amplified transcripts when monolayers of Madin-Darby bovine kidney (MDBK) cells were stimulated with Escherichia coli O157:H7 lipopolysaccharide (LPS) in combination with cycloheximide (CX). Sequence analysis showed that both transcripts encoded members of the alpha C-X-C chemokine family, including interleukin 8 (IL-8) and a protein closely related to bovine growth regulated protein (GRO)-gamma (89% identical). The latter putative epithelial cell inflammatory protein was designated ECIP-1. IL-8 and ECIP-1 genes were placed on the cattle genetic map using single nucleotide polymorphism (SNP) markers amplified from genomic DNA. Multi-point linkage analysis indicated that the gene locations were indistinguishable from those of serum albumin (ALB) and vitamin D-binding protein (GC) on bovine chromosome (BTA) 6. In humans, ALB and GC are located near IL-8, GRO-gamma, and seven other alpha chemokines on chromosome 4 (HSA 4q11-4q13), suggesting that this gene cluster has been conserved on BTA6. These results provide a starting point for characterizing allelic variation in chemokine genes and their roles in the pathogenesis of bacterial infections in cattle.