Article
- The EMBO Journal (2007) 26, 657 - 667
- doi:10.1038/sj.emboj.7601526
Published online: 18 January 2007
Subject Categories:
Afferent neurotransmission mediated by hemichannels in mammalian taste cells
Roman A Romanov1, Olga A Rogachevskaja1, Marina F Bystrova1, Peihua Jiang2, Robert F Margolskee2 and Stanislav S Kolesnikov1
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
- Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York, NY, USA
Correspondence to:
Stanislav S Kolesnikov, Mollecular Physiology of Cell, Institute of Cell Biophysics, Institutional Street 3, Pushchino, Moscow region 142290, Russia. Tel.: +7 496 773 91 21; Fax: +7 496 733 05 09; E-mail: staskolesnikov@yahoo.com
Received 21 July 2006; Accepted 5 December 2006
Abstract
In mammalian taste buds, ionotropic P2X receptors operate in gustatory nerve endings to mediate afferent inputs. Thus, ATP secretion represents a key aspect of taste transduction. Here, we characterized individual vallate taste cells electrophysiologically and assayed their secretion of ATP with a biosensor. Among electrophysiologically distinguishable taste cells, a population was found that released ATP in a manner that was Ca2+ independent but voltage-dependent. Data from physiological and pharmacological experiments suggested that ATP was released from taste cells via specific channels, likely to be connexin or pannexin hemichannels. A small fraction of ATP-secreting taste cells responded to bitter compounds, indicating that they express taste receptors, their G-protein-coupled and downstream transduction elements. Single cell RT–PCR revealed that ATP-secreting taste cells expressed gustducin, TRPM5, PLC
2, multiple connexins and pannexin 1. Altogether, our data indicate that tastant-responsive taste cells release the neurotransmitter ATP via a non-exocytotic mechanism dependent upon the generation of an action potential.
Keywords:
- ATP biosensor,
- ATP release,
- hemichannels,
- neurotransmission,
- taste cells
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