Project A8 - Jutta Engel

Ca2+-channels and exocytosis in hair cells

A better understanding of the function of the inner ear is crucial for the diagnosis of hearing impairment and for current and future therapeutic strategies to restore hearing.

Cochlear hair cells located in the inner ear transform sound signals into neuronal signals. By virtue of their mechanotransducer ion channels, voltage-activated calcium channels open and the resulting calcium influx triggers transmitter release, which activates auditory nerve fibres. Sound information is then transmitted to the brain. A reduction or the absence of calcium currents results in hearing impairment/deafness.

Hair cell calcium currents have special properties such as extremely fast activation kinetics, opening at very negative membrane potentials, and lack of inactivation. The underlying calcium channels consist of the pore-forming subunit Cav1.3 and auxiliary subunits beta and alpha2delta.

In this project part, the contributions of the auxiliary subunit isoforms for current properties and exocytosis will be studied. To this end, we will analyze inner and outer hair cells of mice with constitutive and tissue-specific deletion of particular isoforms of calcium channel subunits.