Abstract
The structural homeostasis of the cochlear hair cell membrane is critical for all aspects of sensory transduction, but the regulation of its maintenance is not well understood. In this report, we analyzed the cochlear hair cells of mice with specific deletion of myosin light chain kinase (MLCK) in inner hair cells. MLCK-deficient mice showed impaired hearing, with a 5- to 14-dB rise in the auditory brainstem response (ABR) thresholds to clicks and tones of different frequencies and a significant decrease in the amplitude of the ABR waves. The mutant inner hair cells produced several ball-like structures around the hair bundles in vivo, indicating impaired membrane stability. Inner hair cells isolated from the knockout mice consistently displayed less resistance to hypoosmotic solution and less membrane F-actin. Myosin light-chain phosphorylation was also reduced in the mutated inner hair cells. Our results suggest that MLCK is necessary for maintaining the membrane stability of inner hair cells.
Highlights
Hearing is achieved through multiple steps; acoustic stimuli are received through the inner hair cells (IHCs) and outer hair cells (OHCs) in the organ of Corti, converted into electric signals, and transmitted to the central nervous system [1]
Strong signals were observed in the IHCs and OHCs [Fig. 1, C and D]
Investigations of hearing loss are limited because the inner ear is positioned deep within the temporal bones, and the physical examination of the human inner ear is possible only post mortem
Summary
Hearing is achieved through multiple steps; acoustic stimuli are received through the inner hair cells (IHCs) and outer hair cells (OHCs) in the organ of Corti, converted into electric signals, and transmitted to the central nervous system [1] These mechano-chemical and mechano-electrical transductions are performed by both cellular components and extracellular structures, and they involve many molecules in the inner ear, such as stretch-activated ion channels, caveolae, integrins, cadherins, growth factor receptors, myosin motors, cytoskeletal filaments, nuclei, extracellular matrix, and numerous other structures and signaling molecules [2]. Hair cells function in signal transduction through apical hair bundles as well as somatic contractility and membrane machineries [2,3,4] These cellular structures are important for the homeostasis of the cochlear hair cells and are highly regulated by cytoskeletal factors, including myosin motors, F-actin bundle proteins and F-actin crosslinking proteins [3,5,6]. We speculated that MLCK might play an important part in hearing
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
