Taste Cells of the Type III Employ CASR to Maintain Steady Serotonin Exocytosis at Variable Ca<sup>2+</sup> in the Extracellular Medium

Type III taste cells are the only taste bud cells which express voltage-gated (VG) Ca<sup>2+</sup> channels and employ Ca<sup>2+</sup>-dependent exocytosis to release neurotransmitters, particularly serotonin. The taste bud is a tightly packed cell population, wherein extrace...

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Main Authors: Aleksandr P. Cherkashin, Olga A. Rogachevskaja, Natalia V. Kabanova, Polina D. Kotova, Marina F. Bystrova, Stanislav S. Kolesnikov
Format: Article
Language:English
Published: MDPI AG 2022-04-01
Series:Cells
Subjects:
Online Access:https://www.mdpi.com/2073-4409/11/8/1369
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author Aleksandr P. Cherkashin
Olga A. Rogachevskaja
Natalia V. Kabanova
Polina D. Kotova
Marina F. Bystrova
Stanislav S. Kolesnikov
author_facet Aleksandr P. Cherkashin
Olga A. Rogachevskaja
Natalia V. Kabanova
Polina D. Kotova
Marina F. Bystrova
Stanislav S. Kolesnikov
author_sort Aleksandr P. Cherkashin
collection DOAJ
description Type III taste cells are the only taste bud cells which express voltage-gated (VG) Ca<sup>2+</sup> channels and employ Ca<sup>2+</sup>-dependent exocytosis to release neurotransmitters, particularly serotonin. The taste bud is a tightly packed cell population, wherein extracellular Ca<sup>2+</sup> is expected to fluctuate markedly due to the electrical activity of taste cells. It is currently unclear whether the Ca<sup>2+</sup> entry-driven synapse in type III cells could be reliable enough at unsteady extracellular Ca<sup>2</sup>. Here we assayed depolarization-induced Ca<sup>2+</sup> signals and associated serotonin release in isolated type III cells at varied extracellular Ca<sup>2+</sup>. It turned out that the same depolarizing stimulus elicited invariant Ca<sup>2+</sup> signals in type III cells irrespective of bath Ca<sup>2+</sup> varied within 0.5–5 mM. The serotonin release from type III cells was assayed with the biosensor approach by using HEK-293 cells co-expressing the recombinant 5-HT4 receptor and genetically encoded cAMP sensor Pink Flamindo. Consistently with the weak Ca<sup>2+</sup> dependence of intracellular Ca<sup>2+</sup> transients produced by VG Ca<sup>2+</sup> entry, depolarization-triggered serotonin secretion varied negligibly with bath Ca<sup>2+</sup>. The evidence implicated the extracellular Ca<sup>2+</sup>-sensing receptor in mediating the negative feedback mechanism that regulates VG Ca<sup>2+</sup> entry and levels off serotonin release in type III cells at deviating Ca<sup>2+</sup> in the extracellular medium.
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spelling doaj.art-5052c9415dd7468c99728bea7a9a1fb72023-12-01T01:15:46ZengMDPI AGCells2073-44092022-04-01118136910.3390/cells11081369Taste Cells of the Type III Employ CASR to Maintain Steady Serotonin Exocytosis at Variable Ca<sup>2+</sup> in the Extracellular MediumAleksandr P. Cherkashin0Olga A. Rogachevskaja1Natalia V. Kabanova2Polina D. Kotova3Marina F. Bystrova4Stanislav S. Kolesnikov5Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino 142290, RussiaPushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino 142290, RussiaPushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino 142290, RussiaPushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino 142290, RussiaPushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino 142290, RussiaPushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino 142290, RussiaType III taste cells are the only taste bud cells which express voltage-gated (VG) Ca<sup>2+</sup> channels and employ Ca<sup>2+</sup>-dependent exocytosis to release neurotransmitters, particularly serotonin. The taste bud is a tightly packed cell population, wherein extracellular Ca<sup>2+</sup> is expected to fluctuate markedly due to the electrical activity of taste cells. It is currently unclear whether the Ca<sup>2+</sup> entry-driven synapse in type III cells could be reliable enough at unsteady extracellular Ca<sup>2</sup>. Here we assayed depolarization-induced Ca<sup>2+</sup> signals and associated serotonin release in isolated type III cells at varied extracellular Ca<sup>2+</sup>. It turned out that the same depolarizing stimulus elicited invariant Ca<sup>2+</sup> signals in type III cells irrespective of bath Ca<sup>2+</sup> varied within 0.5–5 mM. The serotonin release from type III cells was assayed with the biosensor approach by using HEK-293 cells co-expressing the recombinant 5-HT4 receptor and genetically encoded cAMP sensor Pink Flamindo. Consistently with the weak Ca<sup>2+</sup> dependence of intracellular Ca<sup>2+</sup> transients produced by VG Ca<sup>2+</sup> entry, depolarization-triggered serotonin secretion varied negligibly with bath Ca<sup>2+</sup>. The evidence implicated the extracellular Ca<sup>2+</sup>-sensing receptor in mediating the negative feedback mechanism that regulates VG Ca<sup>2+</sup> entry and levels off serotonin release in type III cells at deviating Ca<sup>2+</sup> in the extracellular medium.https://www.mdpi.com/2073-4409/11/8/1369taste cellsvoltage-gated Ca<sup>2+</sup> channelsserotonin secretionserotonin biosensorextracellular Ca<sup>2+</sup>-sensing receptor
spellingShingle Aleksandr P. Cherkashin
Olga A. Rogachevskaja
Natalia V. Kabanova
Polina D. Kotova
Marina F. Bystrova
Stanislav S. Kolesnikov
Taste Cells of the Type III Employ CASR to Maintain Steady Serotonin Exocytosis at Variable Ca<sup>2+</sup> in the Extracellular Medium
Cells
taste cells
voltage-gated Ca<sup>2+</sup> channels
serotonin secretion
serotonin biosensor
extracellular Ca<sup>2+</sup>-sensing receptor
title Taste Cells of the Type III Employ CASR to Maintain Steady Serotonin Exocytosis at Variable Ca<sup>2+</sup> in the Extracellular Medium
title_full Taste Cells of the Type III Employ CASR to Maintain Steady Serotonin Exocytosis at Variable Ca<sup>2+</sup> in the Extracellular Medium
title_fullStr Taste Cells of the Type III Employ CASR to Maintain Steady Serotonin Exocytosis at Variable Ca<sup>2+</sup> in the Extracellular Medium
title_full_unstemmed Taste Cells of the Type III Employ CASR to Maintain Steady Serotonin Exocytosis at Variable Ca<sup>2+</sup> in the Extracellular Medium
title_short Taste Cells of the Type III Employ CASR to Maintain Steady Serotonin Exocytosis at Variable Ca<sup>2+</sup> in the Extracellular Medium
title_sort taste cells of the type iii employ casr to maintain steady serotonin exocytosis at variable ca sup 2 sup in the extracellular medium
topic taste cells
voltage-gated Ca<sup>2+</sup> channels
serotonin secretion
serotonin biosensor
extracellular Ca<sup>2+</sup>-sensing receptor
url https://www.mdpi.com/2073-4409/11/8/1369
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