Identification of novel cyclic nucleotide phosphodiesterase gene cDNAs in the cochlea of guinea pig (Cavia porcellus) through conserved homologous sequences.

The nitric oxide (NO) signaling pathway plays a critical role in auditory signal conversion and transduction. Cyclic nucleotide phosphodiesterase (PDE), an important component of the NO signaling pathway, has not been identified in the cochlea. Using cross-species comparison, homologous sequences of human and mouse Pde coding sequences were searched in a guinea pig genomic database and conserved homologous exons were found between human and mouse homologous sequences. Based on reverse-transcription PCR of these conserved regions, six partial Pde cDNAs were detected in the cochlea: CpPde3a, CpPde4d, CpPde8a, CpPde8b, CpPde9a, and CpPde11a. The identity rates of the six partial Pde cDNA sequences between guinea pig and human range from 83.8 to 95.5% and those of the peptide sequences range from 85.6 to 100%. The identity rates of the six Pde cDNA sequences between guinea pig and mouse range from 80.6 to 93.0% and those of peptide sequences range from 79.5 to 99.2%. The results demonstrate that multiple Pde genes are expressed in the cochlea, suggesting a NO pathway in the auditory system. Insights into this pathway will help to develop new therapeutic drugs on auditory abnormalities.