Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2006
Publication Date: 8/15/2006
Citation: Connor, E.E., Cates, E.A., Williams, J.L., Bannerman, D.D. 2006. Cloning and radiation hybrid mapping of bovine toll-like receptor-4 (TLR-4) signaling molecules. Veterinary Immunology and Immunopathology. 112(3-4):302-308. Interpretive Summary: Toll-like receptor 4 (TLR-4) is thought to play a critical role in the inflammatory response of cells to Gram-negative bacteria, the cause of approximately 40% of clinical cases of masititis in dairy cattle. Knowledge of TLR-4 signaling in cattle is extremely limited. Therefore, the goal of this study was to determine the nucleotide sequences of the bovine genes CASP8, IRAK1, MD-2, TICAM2, TIRAP, TOLLIP and TRAF 6 and determine the chromosomal locations of these genes, as well as MyD88 and TICAM1, within the bovine genome. This work should assist in the assembly and annotation of the bovine genome sequence and facilitate the study of TLR-4 signaling pathways in cattle.
Technical Abstract: Toll-like receptor (TLR)-4 is the putative transmembrane receptor for lipopolysaccharide, a highly pro-inflammatory component of the outer membrane of Gram-negative bacteria. To date, molecules of the TLR-4 signaling pathway have not been well-characterized in cattle. The goal of this study was to clone and sequence the full-length coding regions of bovine genes involved in TLR-4 signaling including CASP8, IRAK1, MD-2, TICAM2, TIRAP, TOLLIP and TRAF 6 and to position these genes, as well as MyD88 and TICAM1, on the bovine genome using radiation hybrid mapping. Results of this work indicate differences with a previously published bovine sequence for MD-2 and a predicted sequence in the GenBank database for TIRAP based on the most recent assembly of the bovine genome. In addition, discrepancies between actual and predicted chromosomal map positions based on the Btau_2.0 genome assembly release were identified, although map positions were consistent with predicted locations based on the current bovine-human comparative map. Alignment of the bovine amino acid sequences with human and murine sequences showed a broad range in conservation, ranging from 52 to 93%. Overall, this work should assist in the assembly and annotation of the bovine genome sequence and facilitate the study of TLR-4 signaling pathways in cattle.