DOI: 10.5061/dryad.905qfttvj
title: Contributions of mirror-image hair cell orientation to mouse otolith organ and zebrafish neuromast function: Part 2/2, Hair cell and afferent physiology from mouse utricle

description: Otolith organs in the inner ear and neuromasts in the fish lateral-line
 harbor two populations of hair cells oriented to detect stimuli in
 opposing directions. The underlying mechanism is highly conserved: the
 transcription factor EMX2 is regionally expressed in just one hair cell
 population and acts through the receptor GPR156 to reverse cell
 orientation relative to the other population. In mouse and zebrafish, loss
 of Emx2 results in sensory organs that harbor only one hair cell
 orientation and are not innervated properly. In zebrafish, Emx2 also
 confers hair cells with reduced mechanosensory properties. Here, we
 leverage mouse and zebrafish models lacking GPR156 to determine how
 detecting stimuli of opposing directions serves vestibular function, and
 whether GPR156 has other roles besides orienting hair cells. We find that
 otolith organs in Gpr156 mouse mutants have normal zonal organization and
 normal type I-II hair cell distribution and mechano-electrical
 transduction properties. In contrast, gpr156 zebrafish mutants lack the
 smaller mechanically-evoked signals that characterize Emx2-positive hair
 cells. Loss of GPR156 does not affect orientation-selectivity of afferents
 in mouse utricle or zebrafish neuromasts. Consistent with normal otolith
 organ anatomy and afferent selectivity, Gpr156 mutant mice do not show
 overt vestibular dysfunction. Instead, performance on two tests that
 engage otolith organs is significantly altered – swimming and
 off-vertical-axis rotation. We conclude that GPR156 relays hair cell
 orientation and transduction information downstream of EMX2, but not
 selectivity for direction-specific afferents. These results clarify how
 molecular mechanisms that confer bi-directionality to sensory organs
 contribute to function, from single hair cell physiology to animal
 behavior.
description: We compared mechano-electrical transduction and whole-cell
 voltage-activated K<sup>+ </sup>currents in verstibular type I
 and type II hair cells from homozygous knockout
 (Gpr156<sup>–</sup><sup>/</sup><sup>–</sup>) animals and heterozygote (Gpr156<sup>+/</sup><sup>–</sup>) littermates. We performed current clamp experiments to investigate firing properties of calyceal afferent nerves. 
description: # Contributions of mirror-image hair cell orientation to mouse otolith
 organ and zebrafish neuromast function: Part 2/2, Hair cell and afferent
 physiology from mouse utricle
 [https://doi.org/10.5061/dryad.905qfttvj](https://doi.org/10.5061/dryad.905qfttvj) ##### Description of the data and file structure This dataset is from the mouse utricle, comparing control tissue with tissue lacking the normal line of reversal of hair bundle polarity (LPR).  Data included are:  whole-cell patch clamp data on hair cell transduction and voltage-gated current properties (Figure 2 and its associated supplementary file 2, F2-FS2; Figure 3 and supplementary file 3, F3-FS3;  Figure 4 and supplementary file 4, F4-FS4) and vestibular afferent properties (Figure 8 and supplementary file 5, F8-FS5).    Datasets are in excel format. Datasets have headers, and additional information is provided in this document. ##### DATA & FILE OVERVIEW Each file corresponds to a parent figure and a Figure supplement containing a table in the manuscript, and contains sufficient data to recreate all statistical tests. Each file contains sheets that are explicitly labelled to refer to condition (cell type, genotype) within that table. Each sheet has header information describing the parameter, condition (genotype, age, zone), and the unique Cell ID of every cell used in the analysis. Some data is repeated in different files if it is used in multiple figures or tables. This is seen if when the unique Cell ID for each data entry is found in multiple files. ##### Files and variables Additional information for some sheets within files is provided below. #### *Filename: F2\_FS2\_sourcedata.xlsx* #### *Sheetname: FS2\_Gpr156*\_*HET, FS2*\_*Gpr156*\_*KO* **Description:**  The sheets named "*FS2*_*Gpr156_HET" and "FS2Gpr156KO*" include the data from Gpr156+/- and Gpr156-/- mice, used to generate Figure Supplement 2, respectively. "none" in the cells indicates that the adaptation component was not detectable by exponential curve fitting. The sheet named "F2_Representatives" includes representative Cell IDs used to generate Figure panels. **Number of Variables: 19** 1. Cell ID: Unique cell identifier 2. Cell type: type I (HCI) or type II (HCII) hair cell 3. Age: postnatal day (P) 4. Sex: male (m) or female (f) 5. tau Vfast: ms, time constant for very fast adaptation component at X1/2 6. tau fast: ms, time constant for fast adaptation component at X1/2 7. tau slow: ms, time constant for slow adaptation component at X1/2 8. OR: nm, 10%~90% operating range of hair bundle  9. Imax: pA, Maximum peak mechano-electrical transduction (MET) current evoked by step-bundle displacement 10. % decay: percentage, extent to which I-MET adapts 11. X1/2: micrometer, displacement that evokes half-maximal *I-MET* 12. dx: micrometer, displacement corresponding to an e-fold rise in *I-MET* 13. Probe scale f: micrometer/V, scale factor of the rigid probe motion 14. A1 amplitude: pA, amplitude of very fast adaptation component at X1/2 15. A2 amplitude: pA, amplitude of fast adaptation component at X1/2 16. A3 amplitude: pA, amplitude of slow adaptation component at X1/2 17. A1 amplitude: %, proportion of very fast adaptation component to overall adaptation at X1/2 18. A2 amplitude: %, proportion of fast adaptation component to overall adaptation at X1/2 19. A3 amplitude: %, proportion of slow adaptation component to overall adaptation at X1/2 #### *Filename: F3\_FS3\_sourcedata.xlsx* #### Sheetname: *FS3\_HCI, FS3*\_*HCII* **Description:** The sheets named "*FS3*_*HCI" and "FS3*_HCII" include the data for type I and type II hair cells used to generate Figure Supplement 3, respectively. The sheet named "F3_Representatives" includes representative Cell IDs used to generate Figure panels. Any blank cells in the file indicate a lack of data for that variable. ##### Number of Variables: 10 1. Cell ID: Unique cell identifier 2. Genotype: Gpr156 knockouts (KO) or heterozygote control (HET) 3. Age: postnatal day (P) 4. Sex: male (m) or female (f) 5. Cm: pF, Cell membrane capacitance 6. Vrest: mV, resting potential 7. V1/2: mV, half maximal activating potential 8. Slope F: mV, the voltage change over which conductance (G) changes e-fold at voltages negative to V1/2 9. Rin: megaOhms, the input resistance 10. Gmax/Cm: nS/pF, conductance density  #### *Filename: F4\_FS4\_sourcedata.xlsx* #### Sheetname: *FS4\_Gpr156\_HET, FS4\_Gpr156\_KO* **Description:**  The sheets named "FS4_Gpr156_HET" and "FS4_Gpr156_KO" include the data for Gpr156 heterozygote control and Gpr156 knockouts used to generate Figure Supplement 4, respectively. "none" in the cells indicates that the adaptation component was not detectable by exponential curve fitting. The sheet named "F4_Representatives" includes representative Cell IDs used to generate Figure panels. ##### **Number of Variables: 17** 1. Cell ID: Unique cell identifier 2. Zone: Location of the cell within utricle; LES, MES or Striola 3. Cell type: type I (HCI) or type II (HCII) hair cell 4. Age: postnatal day (P) 5. Sex: male (m) or female (f) 6. tau Vfast: ms, time constant for very fast adaptation component at X1/2 7. tau fast: ms, time constant for fast adaptation component at X1/2 8. tau slow: ms, time constant for slow adaptation component at X1/2 9. OR: nm, 10~90% operating range of hair bundle  10. Imax: pA, Maximum peak mechano-electrical transduction (MET) current evoked by step-bundle displacement 11. % decay: percentage, extent of I-MET adaptation 12. X1/2: micrometer, displacement that evokes half-maximal *I-MET* 13. dx: micrometer, displacement corresponding to an e-fold rise in *I-MET* 14. Probe scale f: micrometer/V, scale factor of the rigid probe motion 15. A1 amplitude: %, proportion of very fast adaptation component to overall adaptation at X1/2 16. A2 amplitude: %, proportion of fast adaptation component to overall adaptation at X1/2 17. A3 amplitude: %, proportion of slow adaptation component to overall adaptation at X1/2 #### *Filename: F8\_FS5*\_*sourcedata.xlsx* #### Sheetname: *FS5* **Description:** The sheet named "FS5" includes the data from calyceal endings used to generate Figure Supplement 5. The sheet named "F8_Representatives" includes representative Cell IDs used to generate Figure panels. ##### **Number of Variables: 8** 1. Cell ID: Unique cell identifier 2. Genotype: Gpr156 knockouts (KO) or heterozygote control (HET) 3. Age: postnatal day (P) 4. Sex: male (m) or female (f) 5. Transient/Sustained: transient neuron (T) or sustained neuron (S) in response to adequate amount of current injection  6. Vrest: mV, resting potential 7. Rin: megaOhms, the input resistance 8. I-threshold: pA,  threshold step-current that elicited an initial spike This dataset submission is linked with Part 1: DOI: [https://doi.org/10.5061/dryad.m63xsj4br](https://doi.org/10.5061/dryad.m63xsj4br)