Active role of glia‐like supporting cells in the organ of Corti: Membrane proteins and their roles in hearing

Abstract

The organ of Corti, located in the cochlea in the inner ear, is one of the major sensory organs involved in hearing. The organ of Corti consists of hair cells, glia‐like supporting cells, and the cochlear nerve, which work in harmony to receive sound from the outer ear and transmit auditory signals to the cochlear nucleus in the auditory ascending pathway. In this process, maintenance of the endocochlear potential, with a high potassium gradient and clearance of electrolytes and biochemicals in the inner ear, is critical for normal sound transduction. There is an emerging need for a thorough understanding of each cell type involved in this process to understand the sophisticated mechanisms of the organ of Corti. Hair cells have long been thought to be active, playing a primary role in the cochlea in actively detecting and transmitting signals. In contrast, supporting cells are thought to be silent and function to support hair cells. However, growing lines of evidence regarding the membrane proteins that mediate ionic movement in supporting cells have demonstrated that supporting cells are not silent, but actively play important roles in normal signal transduction. In this review, we summarize studies that characterize diverse membrane proteins according to the supporting cell subtypes involved in cochlear physiology and hearing. This review contributes to a better understanding of supporting cell functions and facilitates the development of potential therapeutic tools for hearing loss.

Transgenic Tg(Kcnj10-ZsGreen) fluorescent reporter mice allow visualization of intermediate cells in the stria vascularis

“…While the loss of KCNJ10 in the stria vascularis is connected to the loss of the endocochlear potential 8 , Eckhardt and colleagues have suggested that KCNJ10 expression in supporting cells is related to the involvement of cochlear supporting cells in potassium recycling that is consistent with previous hypotheses 29 . Eckhardt and colleagues also point to the glia-like properties of supporting cells that have been reviewed extensively by others 25 , 32 , 33 , suggesting that KCNJ10 may have similar functions in these two regions of the cochlea 29 . Thus, the mouse model presented in this study provides an opportunity to study the function of cell types, identified by their expression of KCNJ10, in the cochlea, including SV intermediate cells, supporting cells of the organ of Corti, and satellite glial cells.…”

Conditional Ablation of Glucocorticoid and Mineralocorticoid Receptors from Cochlear Supporting Cells Reveals Their Differential Roles for Hearing Sensitivity and Dynamics of Recovery from Noise-Induced Hearing Loss

“…Supporting cells perform multiple functions to maintain auditory sensitivity. Within the epithelial-supporting cells, specialized functions include ionic balance through connexin expression and mechanical support, glia-like functions through neurotrophic factor expression and release, and maintenance of extracellular glutamate levels by the glutamate–glutamine cycle [ 87 , 109 , 110 , 111 , 112 ]. Dysregulation of supporting cell functions including clearance of extracellular glutamate, maintenance of K + ion concentration, and alterations to neurotrophic factors each induce synapse loss [ 94 , 113 , 114 ].…”

Hearing loss and vestibular schwannoma: new insights into Schwann cells implication

“…In addition, HCs are surrounded by glial-like supporting cells, which share many molecular and physiological features with the glial cells of the central nervous system (CNS). These cells, which were thought to be silent and only mechanically supporting HCs, were recently reconsidered as actively playing important roles in auditory transduction [ 11 ]. Glial-like supporting cells also participate in the maturation, proliferation, protection, and regeneration of cochlear cells [ 12 , 13 ].…”