Mitochondrial form and function in hair cells

Hair cells (HCs) are specialised sensory receptors residing in the neurosensory epithelia of inner ear sense organs. The precise morphological and physiological properties of HCs allow us to perceive sound and in-teract with the world around us. Mitochondria play a significant role in normal HC function and are also intricately involved in HC death. They generate ATP essential for sustaining the activity of ion pumps, Ca2 + transporters and the integrity of the stereociliary bundle during transduction as well as regulat-ing cytosolic calcium homoeostasis during synaptic transmission. Advances in imaging techniques have allowed us to study mitochondrial populations throughout the HC, and how they interact with other organelles. These analyses have identified distinct mitochondrial populations between the apical and ba-solateral portions of the HC, in which mitochondrial morphology appears determined by the physiolog-ical processes in the different cellular compartments. Studies in HCs across species show that ototoxic agents, ageing and noise damage directly impact mitochondrial structure and function resulting in HC death. Deciphering the molecular mechanisms underlying this mitochondrial sensitivity, and how their morphology relates to their function during HC death, requires that we first understand this relationship in the context of normal HC function.(c) 2022 The Author(s). Published by Elsevier B.V.This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

Automated summary

Hair cells (HCs) are specialized sensory receptors in the inner ear that allow us to perceive sound and interact with the world. Mitochondria play a crucial role in HC function and death, producing ATP and regulating calcium levels. Imaging techniques have revealed distinct mitochondrial populations in different parts of the HC, and studies have shown that ototoxic agents, aging, and noise damage affect mitochondrial structure and function, leading to HC death. Understanding the relationship between mitochondrial morphology and function in normal HC function is essential for deciphering the molecular mechanisms underlying HC death.