Sequence and structural analysis of feline interleukin-5 cDNA

Abstract

Abstract Objective To clone and characterize the cDNA encoding feline interleukin-5 (IL-5) cDNA and the 170 basepairs (bp) of the 5' flanking region of the feline IL-5 gene. Sample Population Blood mononuclear cells from a healthy cat. Procedures Cells were cultured, stimulated for 48 hours with concanavalin A, and harvested for RNA and DNA isolation. Recovered RNA was used in northern blot and reverse transcription-polymerase chain reaction analyses. Resulting cDNA was used for rapid amplification of 3' cDNA ends, dideoxy chain termination sequencing, and primer extension analysis. Results Full length cDNA was 838 bp, including a 402-bp open reading frame that encoded a precursor protein of 134 amino acids including a putative peptide signal of 19 residues. Homologies of the nucleotide and derived protein sequences between feline and human IL-5 cDNA were 72 and 71%, respectively. There also was homology between the human and predicted feline cytokines at amino acid positions that are critical for IL-5 receptor binding and signal transduction. The 5' flanking region of the feline gene was homologous to corresponding regions of the human (88%) and murine (72%) genes, and included putative transcriptional regulatory elements. Conclusions and Clinical Relevance Identification of feline IL-5 cDNA is an important step toward a detailed, fully comprehensive characterization of the mechanisms that may be operative in the pathogenesis of eosinophilic disorders in cats. The striking homology between the human and feline IL-5 genes suggests that cats can be used as animal models for human diseases characterized by eosinophil infiltration of tissues. (Am J Vet Res 1998;59:1263–1269)