Correct patterning of the mammalian inner ear sensory epithelium, which contains mechanosensory outer hair cells (OHCs) that detect and amplify sound vibrations and non-sensory supporting cells such as pillar cells (PCs), is essential for hearing. The cell surface mechanical properties of both OHCs and PCs are important for their function but how are these properties regulated during development? On , Katherine Szarama and colleagues use atomic force microscopy to show that OHCs and PCs have different cell surface mechanical properties that develop over different time courses. By pharmacologically modulating cytoskeletal elements, they show that the increase in OHC stiffness observed during development depends primarily on actin whereas the development of the cell surface mechanical properties of PCs depends on microtubules. In addition, they report that fibroblast growth factor signalling regulates the developing cell surface mechanical properties of OHCs and PCs, in part by altering cytoskeletal dynamics. These new insights into inner ear development may eventually lead to better treatments for hearing loss.
