Motile Cilia of Human Airway Epithelia Are Chemosensory
Beat It Primary cilia are specialized organelles that serve important sensory functions in many different tissues and cells, and defects in their structure and function underlie a variety of genetic diseases. In contrast to primary cilia, motile cilia serve a mechanical function. For example, the cilia on airway epithelia remove inhaled material from the lung. Shah et al. (p. 1131 , published online 23 July; see the cover; see the Perspective by Kinnamon and Reynolds ) now show that these classic motile cilia are also chemosensory. The motile cilia on airway epithelia contain bitter-taste receptors and their associated signaling machinery. Moreover, application of bitter substances triggers an elevation of intracellular Ca 2+ levels and increases cilia beat frequency. Thus, in airway epithelia, bitter-taste receptors may be able to detect noxious substances entering the airways and initiate an autonomous defensive mechanism designed to accelerate elimination of the offending compound.