Kentucky: Mechanosensory hair cells in the inner ear pick up the softest sounds, such as whispers and distant noises. Unlike other cells in the human body, these sensory cells are fragile and finite. At birth, the human ear contains approximately 15,000 of these cells. They do not regenerate or divide and, therefore are susceptible to permanent damage from exposure to loud sounds. Scientists believe understanding the molecular mechanisms that maintain the structure of these cells throughout the lifespan can provide insight into the fundamental causes of hearing loss and deafness.
University of Kentucky physiologists Catalina Vélez-Ortega, Gregory
Frolenkov and their collaborators in the UK College of Medicine have
discovered a molecular mechanism necessary for stabilizing stereocilia,
the “hairs” of the sensory cells of the inner ear. Stereocilia are
nanoscale structures grouped together in staircase-like rows and
interconnected by extracellular filaments. Hearing happens when sound
vibrations deflect stereocilia, tension the extracellular filaments and
open mechanotransduction ion channels allowing calcium and other ions to
enter the hair cell.
Frolenkov’s team discovered that blockage of these channels cause the
stereocilia to retract and that this retraction depends on the calcium
influx through these channels. UK researchers uncovered the mechanism
maintaining the remarkable staircase-like architecture of the
stereocilia. This contribution provides new insight into the molecular
mechanisms that facilitate the detection of sound within the inner ear,
with opportunities to explore molecular therapies to maintain the
This research will appear in an upcoming issue of eLife.