Decision letter: Live imaging of hair bundle polarity acquisition demonstrates a critical timeline for transcription factor Emx2

Live imaging of hair bundle polarity acquisition demonstrates a critical timeline for transcription factor Emx2

eLife ◽

10.7554/elife.59282 ◽

2020 ◽

Vol 9 ◽

Author(s):

Yosuke Tona ◽

Doris K Wu

Keyword(s):

Transcription Factor ◽

Hair Cells ◽

Time Window ◽

Critical Time ◽

Live Imaging ◽

Hair Bundle ◽

Directional Sensitivity ◽

Mother Centriole ◽

Daughter Centriole

Directional sensitivity of hair cells (HCs) is conferred by the aymmetric apical hair bundle, comprised of a kinocilium and stereocilia staircase. The mother centriole (MC) forms the base of the kinocilium and the stereocilia develop adjacent to it. Previously, we showed that transcription factor Emx2 reverses hair bundle orientation and its expression in the mouse vestibular utricle is restricted, resulting in two regions of opposite bundle orientation (Jiang et al., 2017). Here, we investigated establishment of opposite bundle orientation in embryonic utricles by live-imaging GFP-labeled centrioles in HCs. The daughter centriole invariably migrated ahead of the MC from the center to their respective peripheral locations in HCs. Comparing HCs between utricular regions, centriole trajectories were similar but they migrated toward opposite directions, suggesting that Emx2 pre-patterned HCs prior to centriole migration. Ectopic Emx2, however, reversed centriole trajectory within hours during a critical time-window when centriole trajectory was responsive to Emx2.

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Live imaging of hair bundle polarity acquisition in the mouse utricle demonstrates a critical timeline for transcription factor Emx2

10.1101/2020.05.28.121244 ◽

2020 ◽

Author(s):

Yosuke Tona ◽

Doris K. Wu

Keyword(s):

Transcription Factor ◽

Hair Cells ◽

Time Window ◽

Critical Time ◽

Live Imaging ◽

Hair Bundle ◽

Directional Sensitivity ◽

Mother Centriole ◽

Daughter Centriole

ABSTRACTThe asymmetric hair bundle on top of hair cells (HCs), comprises a kinocilium and stereocilia staircase, dictates HC directional sensitivity. The mother centriole (MC) forms the base of the kinocilium, where stereocilia are subsequently built next to it. Previously we showed that transcription factor Emx2 reverses hair bundle orientation and its expression in the mouse vestibular utricle is restricted, resulting in two regions of opposite bundle orientation (Jiang et al, 2017). Here, we investigated establishment of opposite bundle orientation in embryonic utricles by live-imaging GFP-labeled centrioles in HCs. The daughter centriole invariably migrated ahead of the MC from the center to their respective peripheral locations in HCs. Comparing HCs between utricular regions, centriole trajectories were similar but they migrated towards opposite directions, suggesting that Emx2 pre-patterned HCs prior to centriole migration. Ectopic Emx2, however, reversed centriole trajectory within hours during a critical time-window when centriole trajectory was responsive to Emx2.

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Author response: Live imaging of hair bundle polarity acquisition demonstrates a critical timeline for transcription factor Emx2

10.7554/elife.59282.sa2 ◽

2020 ◽

Author(s):

Yosuke Tona ◽

Doris K Wu

Keyword(s):

Transcription Factor ◽

Live Imaging ◽

Hair Bundle ◽

Author Response

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Emx2 regulates hair cell rearrangement but not positional identity within neuromasts

eLife ◽

10.7554/elife.60432 ◽

2020 ◽

Vol 9 ◽

Author(s):

Sho Ohta ◽

Young Rae Ji ◽

Daniel Martin ◽

Doris K Wu

Keyword(s):

Transcription Factor ◽

Hair Cell ◽

Hair Bundle ◽

Planar Polarity ◽

Cell Rearrangement ◽

Positional Identity

Each hair cell (HC) precursor of zebrafish neuromasts divides to form two daughter HCs of opposite hair bundle orientations. Previously, we showed that transcription factor Emx2, expressed in only one of the daughter HCs, generates this bidirectional HC pattern (Jiang et al., 2017). Here, we asked whether Emx2 mediates this effect by changing location of hair bundle establishment or positions of HCs since daughter HCs are known to switch positions with each other. We showed this HC rearrangement, redefined as two processes named Rock & Roll, is required for positional acquisition of HCs. Apical protrusion formation of nascent HCs and planar polarity signaling are both important for the Rock & Roll. Emx2 facilitates Rock & Roll by delaying apical protrusion of its nascent HCs but it does not determine HCs' ultimate positions, indicating that Emx2 mediates bidirectional HC pattern by changing the location where hair bundle is established in HCs.

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Transcription factor Emx2 controls stereociliary bundle orientation of sensory hair cells

eLife ◽

10.7554/elife.23661 ◽

2017 ◽

Vol 6 ◽

Cited By ~ 37

Author(s):

Tao Jiang ◽

Katie Kindt ◽

Doris K Wu

Keyword(s):

Transcription Factor ◽

Hair Cells ◽

Mirror Image ◽

Hair Bundle ◽

Polarity Reversal ◽

Lateral Line System ◽

Apical Surface ◽

Sensory Organs ◽

Line System ◽

Image Pattern

The asymmetric location of stereociliary bundle (hair bundle) on the apical surface of mechanosensory hair cells (HCs) dictates the direction in which a given HC can respond to cues such as sound, head movements, and water pressure. Notably, vestibular sensory organs of the inner ear, the maculae, exhibit a line of polarity reversal (LPR) across which, hair bundles are polarized in a mirror-image pattern. Similarly, HCs in neuromasts of the zebrafish lateral line system are generated as pairs, and two sibling HCs develop opposite hair bundle orientations. Within these sensory organs, expression of the transcription factor Emx2 is restricted to only one side of the LPR in the maculae or one of the two sibling HCs in neuromasts. Emx2 mediates hair bundle polarity reversal in these restricted subsets of HCs and generates the mirror-image pattern of the sensory organs. Downstream effectors of Emx2 control bundle polarity cell-autonomously via heterotrimeric G proteins.

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Author response for "Identification of Retinal Ganglion Cell Types and Brain Nuclei expressing the transcription factor Brn3c/Pou4f3 using a Cre recombinase knock‐in allele"

10.1002/cne.25065/v2/response1 ◽

2020 ◽

Author(s):

Nadia Parmhans ◽

Anne Drury Fuller ◽

Eileen Nguyen ◽

Katherine Chuang ◽

David Swygart ◽

...

Keyword(s):

Transcription Factor ◽

Ganglion Cell ◽

Retinal Ganglion Cell ◽

Cell Types ◽

Cre Recombinase ◽

Author Response ◽

Retinal Ganglion ◽

Brain Nuclei

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Transcription factor/DNA interactions visualized by electron spectroscopic imaging

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122654 ◽

1992 ◽

Vol 50 (1) ◽

pp. 450-451

Author(s):

David P. Bazett-Jones ◽

Mark L. Brown

Keyword(s):

Transcription Factor ◽

Dna Sequences ◽

Transcription Initiation ◽

Molecular Mechanisms ◽

Phosphorus Content ◽

Spectroscopic Imaging ◽

Electron Spectroscopic Imaging ◽

Dna Backbone ◽

Two Parameters ◽

High Level

A multisubunit RNA polymerase enzyme is ultimately responsible for transcription initiation and elongation of RNA, but recognition of the proper start site by the enzyme is regulated by general, temporal and gene-specific trans-factors interacting at promoter and enhancer DNA sequences. To understand the molecular mechanisms which precisely regulate the transcription initiation event, it is crucial to elucidate the structure of the transcription factor/DNA complexes involved. Electron spectroscopic imaging (ESI) provides the opportunity to visualize individual DNA molecules. Enhancement of DNA contrast with ESI is accomplished by imaging with electrons that have interacted with inner shell electrons of phosphorus in the DNA backbone. Phosphorus detection at this intermediately high level of resolution (≈lnm) permits selective imaging of the DNA, to determine whether the protein factors compact, bend or wrap the DNA. Simultaneously, mass analysis and phosphorus content can be measured quantitatively, using adjacent DNA or tobacco mosaic virus (TMV) as mass and phosphorus standards. These two parameters provide stoichiometric information relating the ratios of protein:DNA content.

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