# Illuminating the structure and function of Type I taste cells

> **NIH NIH R01** · UNIVERSITY OF COLORADO DENVER · 2020 · $504,534

## Abstract

Abstract
Taste buds are multicellular sensors reporting taste, which reflects quality and potential toxicity for potential
food items. Two of the 3 cell types (Type II and Type III) comprising a taste bud are well described in terms of
molecular features for transduction and transmission of different taste qualities whereas Type I cells are
described as being supporting or glial-like. In this proposal we test the hypothesis that Type I taste cells serve
two critical functions. First, our preliminary reconstructions of taste buds show that Type I cells completely
surround and separate other cell types in a taste bud; thus Type I cells must be important for signaling and
integration of taste information within the bud. Second, our ultrastructural analysis further shows that some
Type I cells extend an apical process through the taste pore to sample the oral contents and so may transduce
some components of salty taste. We propose to use correlated anatomical, functional and molecular means to
classify and characterize Type I cells in taste buds from mice. The first set of experiments will extend our
preliminary analysis of Type I cells in circumvallate taste buds to test whether Type I cells in fungiform taste
buds similarly separate Type II and Type III cells from one another. Further we test whether the Type I cells
participate in intrabud signaling by releasing GABA or other neurotransmitters in response to the ATP released
by stimulated Type II (sweet-bitter-umami) cells. The GABA can then act on adjacent Type II cells to terminate
signaling and reduce subsequent responsiveness to tastants. In Aim 2, we test whether any morphological
subtype of Type I cells expresses functional amiloride-sensitive salt (ENaC) receptors and if so, determine the
relationship of these cells to sensory nerve fibers. Conventional EM indicates that Type I cells do not form
synapses leaving open the question of how any Type I cell response could be communicated to the nervous
system. We suggest that Type I cells, like glial cells in the CNS, can release neurotransmitter by reversal of
membrane transporters for GABA or glutamate or opening of large pore channels. In the end we will have
resolved two important questions in transduction and transmission of taste information by defining the nature of
intrabud signaling between receptor cell types, and secondly finally determining the identity of cells underlying
amiloride-sensitive salt transduction.

## Key facts

- **NIH application ID:** 9816625
- **Project number:** 5R01DC017679-02
- **Recipient organization:** UNIVERSITY OF COLORADO DENVER
- **Principal Investigator:** Sue C. Kinnamon
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $504,534
- **Award type:** 5
- **Project period:** 2018-12-01 → 2023-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9816625

## Citation

> US National Institutes of Health, RePORTER application 9816625, Illuminating the structure and function of Type I taste cells (5R01DC017679-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9816625. Licensed CC0.

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