Regenerative pathways in the avian cochlea

Project Summary / Abstract It is known for more than 30 years that supporting cells in the normally quiescent avian hearing organ, the basilar papilla, can respond to sensory hair cell death with S-phase entry, mitotic division, and generation of replacement hair cells. The work proposed here utilizes several methodological advances for an unbiased, comprehensive, and systematic inventorying of changes in gene expression during aminoglycoside-induced hair cell death and in responding supporting cells. Pilot data obtained at multiple time points from single cells isolated from the chicken basilar papilla sensory epithelium revealed that activation of a novel pathway linked to protease-activated receptor-2, PAR2, is essential for S-phase entry of supporting cells and hair cell regeneration. The project puts forward a speci?c hypothesis for the activation pathway, which will be explicitly and thoroughly evaluated. Moreover, the identi?ed e?ector genes for the novel regeneration pathway will be assessed in a new adult mouse model for long-term hair cell loss. Here, the focus is on S-phase entry of mouse utricle and organ of Corti supporting cells four weeks after aminoglycoside-induced hair cell loss. Finally, the project will focus on the characterization of newly regenerated hair cells by reconstructing the temporal transcriptomic changes that happen when the new hair cells mature. In parallel, it is proposed to align transcriptomic data with in situ observations such as hair bundle formation, changes in planar cell polarity, reestablishment of synaptic connections, and electrophysiological features such as mechanoelectrical transduction and electrical tuning.