# Molecular and functional characterization of type I and II vestibular hair cells in adult mice

> **NIH NIH F31** · UNIVERSITY OF WASHINGTON · 2024 · $48,974

## Abstract

Project Abstract
 The sensory receptors for mammalian vestibular organs, called hair cells, encode head movements
and relay information along the vestibular nerve to the brainstem and cerebellum. Mammals have two types of
hair cell, type I and type II, which different morphological and physiological properties. Type I and II hair cells
also have distinct forms of afferent innervation that are differentially distributed across the epithelial zones.
Vestibular hair cells die during normal aging and after exposure to ototoxins, and this loss can lead to profound
vestibular deficits. After vestibular hair cell damage in adult mice, supporting cells regenerate ~50% of type ll
hair cells, but no type I hair cells are replaced. This natural hair cell regeneration does not restore the
vestibular system to normal function, as measured by the vestibulo-ocular reflex and other behavioral tests.
One interpretation of this finding is that type I hair cells must be replaced in mammals for vestibular function to
return. While this is tempting to speculate, there is little evidence that type I hair cells are required for specific
vestibular functions. Indeed, we understand little about the respective contributions of type I and II hair cells to
our vestibular sense.
 One step toward solving this puzzle is to use molecular biology to better understand the unique
features of each hair cell type and to determine if subtypes of type I and II hair cells exist. Working with Drs.
Neil Segil and Litao Tao, I found from single cell RNA sequencing that there seem to be four molecularly
distinct populations of hair cells in adult mouse utricles: two type l-like populations, one type ll-like population,
and one unknown group of hair cells. In Aim 1, I will continue these studies, examining expression of
candidate cell-specific genes in all vestibular organs to determine if four distinct hair cell groups are identifiable
in each organ and how these groups are distributed across epithelial zones. I will generate novel insights into
hair cell features across vestibular organs, classify new markers for each cell type, and identify genes that may
be used to drive cell-selective gene misexpression in future studies. Another step toward testing the different
functions of type I and II hair cells is to remove each hair cell population and assess impacts on vestibular
function. In Aim 2, I will use CreLoxP technology to ablate all type I hair cells or peripheral type I hair cells in
all adult vestibular organs. I will determine the impact of these ablations upon animal behaviors and brainstem
electrical responses to vestibular stimuli, which to my knowledge has not been done before in adult mice. I
expect to gain new insights into the general function of type I hair cells and the specific functions of type I hair
cells in each epithelial zone. Overall, this research provides new information about properties and functions of
type I and II hair cells and inform on new therapies to tre...

## Key facts

- **NIH application ID:** 11007165
- **Project number:** 5F31DC020060-02
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** Amanda Nichole Ciani
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $48,974
- **Award type:** 5
- **Project period:** 2023-07-06 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11007165

## Citation

> US National Institutes of Health, RePORTER application 11007165, Molecular and functional characterization of type I and II vestibular hair cells in adult mice (5F31DC020060-02). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/11007165. Licensed CC0.

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