Prestin, a key player in outer hair cells electromotility, and the a10

FRANCHINI L; ELGOYHEN AB

Pinamar

Congreso; SAIB XLI Annual Meeting, X PABMB Meeting, XX SAN Meeting; 2005

The presence of outer hair cells (OHC) only in the mammalian cochlea and of OHCs active mechanisms, makes the mammalian cochlea a unique hearing device which has the capability of detecting a wide range of frequencies including the highest (more than 100 kHz) in the animal world. Several lines of evidence suggest that the motor protein prestin and á9á10-containing nicotinic receptors (nAChRs) are key players in the function or regulation of OHC active mechanisms. In order to understand how this system evolved only in the lineage leading to mammals we performed an evolutionary molecular analysis of these proteins. Prestin underwent some dramatic changes, especially in the sulphate transporter and antisigma-factor antagonist domain, after the split between mammals and birds. In addition, in placental mammals this gene is under strong purifying selection, suggesting that its function is highly important for these organisms’ fitness and adaptation. On the other hand, the á10 nAChR subunit (but not á9) shows signatures of positive selection along the lineage conducting to mammals, suggesting a possible correlation between unique OHC characteristics and the evolution of new functions for this receptor subunit. Thus, we describe at the molecular level signatures of adaptive evolution of two OHC proteins in the lineage leading to mammals reflecting the importance of these proteins in OHC somatic electromotility.