Developing and regenerating a sense of taste

Gustation, or the sense of taste, is essential for distinguishing harmful and nutritious substances, and therefore crucial for health and survival. Taste buds (TBs) located in specialized gustatory papillae on the dorsal surface of the tongue are assemblages of specialized epithelial cells called taste receptor cells (TRCs). With the help of saliva, TRCs transduce sweet, sour, salt, bitter and umami stimuli into electrochemical signals that are transmitted to the brain via gustatory sensory neurons of the VII^th and IX^th cranial ganglia. TBs in the anterior tongue are derived from embryonic ectoderm, while those in the posterior tongue arise from the endoderm. However, regardless of origin and location, all cells in adult taste buds are continually and reliably renewed, such that the sense of taste remains constant. Disruption of this regenerative process in disease or injury can lead to taste dysfunction, or dysgeusia, which negatively impacts quality of life. Decades of research into development and maintenance of adult taste epithelium have revealed molecular and cellular mechanisms underlying these processes. Here, we discuss current findings in the context of the original discoveries related to taste development and regeneration, as well as the transition from developmental to homeostatic mechanisms. Additionally, we review what is currently understood of how cancer therapies cause taste dysfunction and how the taste periphery responds to injury and inflammation. Finally, we consider future directions for the taste field and discuss several outstanding questions for further investigation.