Prestin, a key player in outer hair cell electromotility, and the α10 nicotinic cholinergic subunit show positive selection signatures in the mammalian lineage.

FRANCHINI L; ELGOYHEN AB

Baltimore, USA

Congreso; 29th Midwinter Meeting-Association for Research in Otolaryngology; 2006

The presence of Outer Hair Cell (OHC) 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 evidences suggest that the motor protein prestin and á9á10 containing nAChRs are key players in the function of OHCs active mechanisms within the mammalian cochlea. In order to understand how this system evolved only in the lineage leading to mammals we performed an evolutionary molecular analysis of these proteins. Our results show that prestin underwent some dramatic changes, especially in the sulphate transporter and antisigma-factor antagonist (STAS) domain, after the split between mammals and birds. In addition our data indicate that 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 only 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. This finding is most likely related with the roles these proteins play in OHC somatic electromotility.