Sox2 and Sox3 are essential for development and regeneration of the zebrafish lateral line

ABSTRACTThe recovery of injured or lost sensory neurons after trauma, disease or aging is a major scientific challenge. Upon hearing loss or balance disorder, regeneration of mechanosensory hair cells has been observed in fish, some amphibians and under special circumstances in birds, but is absent in adult mammals. In aquatic vertebrates, hair cells are not only present in the inner ear but also in neuromasts of the lateral line system. The zebrafish lateral line neuromast has an almost unlimited capacity to regenerate hair cells. This remarkable ability is possible due to the presence of neural stem/progenitor cells within neuromasts. In order to further characterize these stem cells, we use the expression of the neural progenitor markers Sox2 and Sox3, transgenic reporter lines, and morphological and topological analysis of the different cell types within the neuromast. We reveal new sub-populations of supporting cells, the sustentacular supporting cells and the neuromast stem cells. In addition, using loss-of-function and mutants of sox2 and sox3, we find that the combined activity of both genes is essential for lateral line development and regeneration. The capability of sox2/sox3 expressing stem cells to produce new hair cells, hair cell-precursors, and supporting cells after damage was analyzed in detail by time-lapse microscopy and immunofluorescence. We are able to provide evidence that sox2/3 expressing cells are the main contributors to the regenerated neuromast, and that their daughter cells are able to differentiate into most cell types of the neuromast.

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Using light-sheet microscopy to study spontaneous activity in the developing lateral-line system

10.1101/2021.11.23.469686 ◽

2021 ◽

Author(s):

Qiuxiang Zhang ◽

Katie Kindt

Keyword(s):

Spontaneous Activity ◽

Lateral Line ◽

Hair Cells ◽

Light Sheet ◽

Lateral Line System ◽

Supporting Cells ◽

Line System ◽

Calcium Activity ◽

Light Sheet Microscopy ◽

Calcium Indicators

Hair cells are the sensory receptors in the auditory and vestibular systems of all vertebrates, and in the lateral-line system of aquatic vertebrates. During development, spontaneous activity in hair cells shapes the formation of these sensory systems. In auditory hair cells of mice, coordinated waves of spontaneous activity can be triggered by concomitant activity in nearby supporting cells. But in mammals, developing auditory and vestibular hair cells can also autonomously generate spontaneous events independent of supporting cell activity. To date, significant progress has been made studying spontaneous activity in the auditory and vestibular systems of mammals, in isolated cultures. The purpose of this work is to explore the zebrafish lateral-line system as a model to study and understand spontaneous activity in vivo. Our work applies genetically encoded calcium indicators along with light-sheet fluorescence microscopy to visualize spontaneous calcium activity in the developing lateral-line system. Consistent with our previous work, we show that spontaneous calcium activity is present in developing lateral-line hair cells. We now show that supporting cells that surround hair cells, and cholinergic efferent terminals that directly contact hair cells are also spontaneously active. Using two-color functional imaging we demonstrate that spontaneous activity in hair cells does not correlate with activity in either supporting cells or cholinergic terminals. We find that during lateral-line development, hair cells autonomously generate spontaneous events. Using localized calcium indicators, we show that within hair cells, spontaneous calcium activity occurs in two distinct domains-the mechanosensory bundle and the presynapse. Further, spontaneous activity in the mechanosensory bundle ultimately drives spontaneous calcium influx at the presynapse. Comprehensively, our results indicate that in developing lateral-line hair cells, autonomously generated spontaneous activity originates with spontaneous mechanosensory events. Overall, with robust spontaneous activity three different cell types, the developing lateral line is a rich model to study these activities in an intact sensory organ. Future work studying this model may further our understanding of these activities and their role in sensory system formation, function and regeneration.

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S-100 protein is a selective marker for sensory hair cells of the lateral line system in teleosts

Neuroscience Letters ◽

10.1016/s0304-3940(02)00597-9 ◽

2002 ◽

Vol 329 (2) ◽

pp. 133-136 ◽

Cited By ~ 17

Author(s):

F Abbate ◽

S Catania ◽

A Germanà ◽

T González ◽

B Diaz-Esnal ◽

...

Keyword(s):

Lateral Line ◽

Hair Cells ◽

Lateral Line System ◽

Selective Marker ◽

Line System ◽

Sensory Hair ◽

Sensory Hair Cells ◽

S 100

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Regenerated hair cells can originate from supporting cell progeny: evidence from phototoxicity and laser ablation experiments in the lateral line system

Journal of Neuroscience ◽

10.1523/jneurosci.10-08-02502.1990 ◽

1990 ◽

Vol 10 (8) ◽

pp. 2502-2512 ◽

Cited By ~ 141

Author(s):

KJ Balak ◽

JT Corwin ◽

JE Jones

Keyword(s):

Laser Ablation ◽

Lateral Line ◽

Hair Cells ◽

Supporting Cell ◽

Lateral Line System ◽

Line System

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Gentamicin is ototoxic to all hair cells in the fish lateral line system

Hearing Research ◽

10.1016/j.heares.2010.01.001 ◽

2010 ◽

Vol 261 (1-2) ◽

pp. 42-50 ◽

Cited By ~ 62

Author(s):

William J. Van Trump ◽

Sheryl Coombs ◽

Kyle Duncan ◽

Matthew J. McHenry

Keyword(s):

Lateral Line ◽

Hair Cells ◽

Lateral Line System ◽

Line System

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The zebrafish homologs of SET/I2PP2A oncoprotein: expression patterns and insights into their physiological roles during development

Biochemical Journal ◽

10.1042/bcj20160523 ◽

2016 ◽

Vol 473 (24) ◽

pp. 4609-4627 ◽

Cited By ~ 4

Author(s):

Iliana Serifi ◽

Eleni Tzima ◽

Katerina Soupsana ◽

Zoe Karetsou ◽

Dimitris Beis ◽

...

Keyword(s):

Amino Acids ◽

Lateral Line ◽

Gene Networks ◽

Expression Patterns ◽

Otic Vesicle ◽

Lateral Line System ◽

Loss Of Function ◽

Line System ◽

Eye Retina

The oncoprotein SET/I2PP2A (protein phosphatase 2A inhibitor 2) participates in various cellular mechanisms such as transcription, cell cycle regulation and cell migration. SET is also an inhibitor of the serine/threonine phosphatase PP2A, which is involved in the regulation of cell homeostasis. In zebrafish, there are two paralogous set genes that encode Seta (269 amino acids) and Setb (275 amino acids) proteins which share 94% identity. We show here that seta and setb are similarly expressed in the eye, the otic vesicle, the brain and the lateral line system, as indicated by in situ hybridization labeling. Whole-mount immunofluorescence analysis revealed the expression of Seta/b proteins in the eye retina, the olfactory pit and the lateral line neuromasts. Loss-of-function studies using antisense morpholino oligonucleotides targeting both seta and setb genes (MOab) resulted in increased apoptosis, reduced cell proliferation and morphological defects. The morphant phenotypes were partially rescued when MOab was co-injected with human SET mRNA. Knockdown of setb with a transcription-blocking morpholino oligonucleotide (MOb) resulted in phenotypic defects comparable with those induced by setb gRNA (guide RNA)/Cas9 [CRISPR (clustered regularly interspaced short palindromic repeats)-associated 9] injections. In vivo labeling of hair cells showed a significantly decreased number of neuromasts in MOab-, MOb- and gRNA/Cas9-injected embryos. Microarray analysis of MOab morphant transcriptome revealed differential expression in gene networks controlling transcription in the sensory organs, including the eye retina, the ear and the lateral line. Collectively, our results suggest that seta and setb are required during embryogenesis and play roles in the zebrafish sensory system development.

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Larval zebrafish rapidly sense the water flow of a predator's strike

Biology Letters ◽

10.1098/rsbl.2009.0048 ◽

2009 ◽

Vol 5 (4) ◽

pp. 477-479 ◽

Cited By ~ 93

Author(s):

M.J. McHenry ◽

K.E. Feitl ◽

J.A. Strother ◽

W.J. Van Trump

Keyword(s):

Water Flow ◽

Lateral Line ◽

Hair Cells ◽

Escape Response ◽

Neuromuscular Control ◽

Lateral Line System ◽

Line System ◽

Novel Device ◽

Larval Fishes ◽

Mechanosensory Hair Cells

Larval fishes have a remarkable ability to sense and evade the feeding strike of a predator fish with a rapid escape manoeuvre. Although the neuromuscular control of this behaviour is well studied, it is not clear what stimulus allows a larva to sense a predator. Here we show that this escape response is triggered by the water flow created during a predator's strike. Using a novel device, the impulse chamber, zebrafish ( Danio rerio ) larvae were exposed to this accelerating flow with high repeatability. Larvae responded to this stimulus with an escape response having a latency (mode=13–15 ms) that was fast enough to respond to predators. This flow was detected by the lateral line system, which includes mechanosensory hair cells within the skin. Pharmacologically ablating these cells caused the escape response to diminish, but then recover as the hair cells regenerated. These findings demonstrate that the lateral line system plays a role in predator evasion at this vulnerable stage of growth in fishes.

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Insights into Electroreceptor Development and Evolution from Molecular Comparisons with Hair Cells

Integrative and Comparative Biology ◽

10.1093/icb/icy037 ◽

2018 ◽

Vol 58 (2) ◽

pp. 329-340 ◽

Cited By ~ 12

Author(s):

Clare V H Baker ◽

Melinda S Modrell

Keyword(s):

Gene Expression ◽

Hair Cell ◽

Electric Fields ◽

Lateral Line ◽

Hair Cells ◽

Water Movement ◽

Low Frequency ◽

Lateral Line System ◽

Line System ◽

Ribbon Synapses

Abstract The vertebrate lateral line system comprises a mechanosensory division, with neuromasts containing hair cells that detect local water movement (“distant touch”); and an electrosensory division, with electrosensory organs that detect the weak, low-frequency electric fields surrounding other animals in water (primarily used for hunting). The entire lateral line system was lost in the amniote lineage with the transition to fully terrestrial life; the electrosensory division was lost independently in several lineages, including the ancestors of frogs and of teleost fishes. (Electroreception with different characteristics subsequently evolved independently within two teleost lineages.) Recent gene expression studies in a non-teleost actinopterygian fish suggest that electroreceptor ribbon synapses employ the same transmission mechanisms as hair cell ribbon synapses, and show that developing electrosensory organs express transcription factors essential for hair cell development, including Atoh1 and Pou4f3. Previous hypotheses for electroreceptor evolution suggest either that electroreceptors and hair cells evolved independently in the vertebrate ancestor from a common ciliated secondary cell, or that electroreceptors evolved from hair cells. The close developmental and putative physiological similarities implied by the gene expression data support the latter hypothesis, i.e., that electroreceptors evolved in the vertebrate ancestor as a “sister cell-type” to lateral line hair cells.

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