INTERNATIONAL SYMPOSIUM ON OLFACTION AND TASTE Symposium Overview Stem Cells in Sensory Epithelium Development and Regeneration Linda A. Barlow a and Anne L. Calof b a b Department of Cell and Developmental Biology and the Rocky Mountain Taste & Smell Center, University of Colorado Denver, School of Medicine, Aurora, Colorado, USA Department of Anatomy & Neurobiology and the Center for Complex Biological Systems, University of California, Irvine, California, USA Many adult tissues are renewed throughout life via processes that are either known or thought to rely on a population of tissue-specific stem cells. For example, studies of both skin and brain have identified local stem cells that have complex interactions with their niche environ- ment, leading to regulated cell genesis. The senses of both smell and taste are well known to be mediated by sensory epithelia that are also continually replaced, although the mecha- nisms that govern renewal are less well under- stood. In this symposium, we showcased some recent advances in development of the taste and olfactory periphery, with the hope of shed- ding light on potential mechanisms governing adult renewal of these sensory epithelia. These chemical senses presentations were bookended by talks pertaining to regeneration and mainte- nance of auditory and skin epithelia in adults. The purpose here was to highlight potential parallels in our understanding of molecular and cellular mechanisms regulating auditory hair cells and skin with cell renewal in chemosen- sory epithelia. Neil Segil (House Ear Institute, Los Ange- les) began with an overview of his work on the development and potential for regeneration of auditory hair cells. In vertebrates, hair cells of the inner ear are delicate mechanoreceptors that transduce pressure waves into electrical sig- nals interpreted by the nervous system. In many species, including birds, amphibians, and fishes, these hair cells can be generated in the event of injury or to accommodate growth; however, mammals appear to have lost this regenerative capacity during evolution. Thus, the mecha- nisms that restrict regeneration in mammals are of great interest to both developmental neu- robiologists and clinicians. One exciting idea explored by Dr. Segil is that under certain con- ditions mammalian auditory epithelium may be able to regenerate. Specifically, as is the case in birds, a population of mammalian auditory support cells, located adjacent to hair cells, may be able to reactivate the potential to give rise to new hair cells by altering levels of key cell cycle inhibitors and through alteration of signaling through the Notch pathway. After this introduction to key concepts in sen- sory epithelium differentiation, Shoba Thiru- mangalathu (University of Colorado Denver, School of Medicine) discussed development of the taste epithelium, focusing on her stud- ies to identify the embryonic cell population that gives rise to adult taste buds. She em- ployed inducible and tissue-specific molecular genetic mouse models to label the developing tongue epithelium as the first taste structures— the taste placodes—form, and to follow these cells and their progeny through to adult stages. Although it has long been assumed that taste placodes represent taste papillae, which in turn Address for correspondence: Linda A. Barlow, University of Colorado, Denver, School of Medicine, Dept of cell & Developmental Biology, Mail Stop 8108, 12801 East 17th Avenue, Room L18-11121, Aurora, CO 80045. Voice: 303/724-3438; fax: 303/724-3420. linda.barlow@ ucdenver.edu International Symposium on Olfaction and Taste: Ann. N.Y. Acad. Sci. 1170: 5–6 (2009). c 2009 New York Academy of Sciences. doi: 10.1111/j.1749-6632.2009.04108.x