Ca2+ signaling, apoptosis and autophagy in the developing cochlea: Milestones to hearing acquisition

Abstract

In mammals, the sense of hearing arises through a complex sequence of morphogenetic events that drive the sculpting of the auditory sensory epithelium into its terminally functional three-dimensional shape. While the majority of the underlying mechanisms remain unknown, it has become increasingly clear that Ca²⁺ signaling is at center stage and plays numerous fundamental roles both in the sensory hair cells and in the matrix of non-sensory, epithelial and supporting cells, which embed them and are tightly interconnected by a dense network of gap junctions formed by connexin 26 (Cx26) and connexin 30 (Cx30) protein subunits. In this review, we discuss the intricate interplay between Ca²⁺ signaling, connexin expression and function, apoptosis and autophagy in the crucial steps that lead to hearing acquisition.

Keywords: ATP; Ca(2+) waves; Caspase-3; Connexins; Deafness; Development; Greater epithelial ridge; IP(3); Inner hair cells; Lesser epithelial ridge; Mitochondria; Morphogenesis; Mouse models; Outer hair cells; Peripheral auditory system; Spiral ganglion neurons.