Comparative sequences of the canine and feline vasopressin prohormones

Vasopressin (VP, antidiuretic hormone) is synthesized as a prohormone consisting of four domains: a signal sequence, the VP nonapeptide, neurophysin II (NP II), and a C-terminal glycopeptide. It plays a key role in cardiovascular homeostasis by regulating renal tubular water reabsorption and urine production. As part of our ongoing studies of the hormonal effects of heart failure in dogs and cats, we have been determining, when not known, the nucleotide and amino acid sequences of relevant peptide hormones. This information will be used to assist in the development and selection of regions of the prohormone for further study and the selection of molecular and antibody probes. To determine the comparative nucleotide and amino acid sequences of canine and feline VP, total RNA was extracted from feline and canine hypothalamus to obtain complementary DNA (cDNA) by reverse transcriptase polymerase chain reaction (RT-PCR) using oligo-T primers. Consensus primers were designed and used for PCR of the resulting cDNA, and the PCR products were then sequenced and analyzed. Each VP sequence was compared to the VP from several mammalian species by alignment with sequences obtained from the GenBank database at the National Center for Biotechnology Information (NCBI). The complete sequence of the canine prohormone was consequently derived from raw data available from the canine Whole Genome Shotgun sequencing site at NCBI. Canine and feline VP prohormones share a high degree of homology with that of other known mammalian species in the VP hormone and NP II domains. The nine amino acid code of canine and feline VP (CYFQNCPRG) is identical to that found in human beings, cows, mice, and rats. The sequence differs by one amino acid from that of swine. The results of this study should be of help in the design and use of antibodies and molecular probes for future studies.