Dataset Information

Assaying sensory ciliopathies using calcium biosensor expression in zebrafish ciliated olfactory neurons.

ABSTRACT:

Background

Primary cilia mediate signal transduction by acting as an organizing scaffold for receptors, signalling proteins and ion channels. Ciliated olfactory sensory neurons (OSNs) organize olfactory receptors and ion channels on cilia and generate a calcium influx as a primary signal in odourant detection. In the zebrafish olfactory placode, ciliated OSNs and microvillus OSNs constitute the major OSN cell types with distinct odourant sensitivity.

Methods

Using transgenic expression of the calcium biosensor GCaMP5 in OSNs, we analysed sensory cilia-dependent odour responses in live zebrafish, at individual cell resolution. oval/ift88 mutant and ift172 knockdown zebrafish were compared with wild-type siblings to establish ciliated OSN sensitivity to different classes of odourants.

Results

oval/ift88 mutant and ift172 knockdown zebrafish showed fewer and severely shortened OSN cilia without a reduction in OSN number. The fraction of responding OSNs and response amplitudes to bile acids and food odour, both sensed by ciliated OSNs, were significantly reduced in ift88 mutants and ift172-deficient embryos, while the amino acids responses were not significantly changed.

Conclusions

Our approach presents a quantitative model for studying sensory cilia signalling using zebrafish OSNs. Our results also implicate ift172-deficiency as a novel cause of hyposmia, a reduced sense of smell, highlighting the value of directly assaying sensory cilia signalling in vivo and supporting the idea that hyposmia can be used as a diagnostic indicator of ciliopathies.

SUBMITTER: Bergboer JGM

PROVIDER: S-EPMC5856005 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Publications

Assaying sensory ciliopathies using calcium biosensor expression in zebrafish ciliated olfactory neurons.

Bergboer Judith G M JGM Wyatt Cameron C Austin-Tse Christina C Yaksi Emre E Drummond Iain A IA

Cilia 20180315

<h4>Background</h4>Primary cilia mediate signal transduction by acting as an organizing scaffold for receptors, signalling proteins and ion channels. Ciliated olfactory sensory neurons (OSNs) organize olfactory receptors and ion channels on cilia and generate a calcium influx as a primary signal in odourant detection. In the zebrafish olfactory placode, ciliated OSNs and microvillus OSNs constitute the major OSN cell types with distinct odourant sensitivity.<h4>Methods</h4>Using transgenic expre ...[more]

PMID: 29568513

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Project description:Olfactory sensory neurons choose to express a single odorant receptor (OR) from a large gene repertoire and extend axons to reproducible, OR-specific locations within the olfactory bulb. This developmental process produces a topographically organized map of odorant experience in the brain. The axon guidance mechanisms that generate this pattern of connectivity, as well as those that coordinate OR choice and axonal guidance receptor expression, are incompletely understood. We applied the powerful approach of single-cell RNA-seq on newly born olfactory sensory neurons (OSNs) in young zebrafish larvae to address these issues. Expression profiles were generated for 56 individual Olfactory Marker Protein (OMP) positive sensory neurons by single-cell (SC) RNA-seq. We show that just as in mouse OSNs, mature zebrafish OSNs typically express a single predominant OR transcript. Our previous work suggests that OSN targeting is related to the OR clade from which a sensory neuron chooses to express its odorant receptor. We categorized each of the mature cells based on the clade of their predominantly expressed OR. Transcripts expressed at higher levels in each of three clade-related categories were identified using Penalized Linear Discriminant Analysis (PLDA). A genome-wide approach was used to identify membrane-associated proteins that are most likely to have guidance-related activity. We found that OSNs that choose to express an OR from a particular clade also express specific subsets of potential axon guidance genes and transcription factors. We validated our identification of candidate axon guidance genes for one clade of OSNs using bulk RNA-seq from a subset of transgene-labeled neurons that project to a single protoglomerulus. The differential expression patterns of selected candidate guidance genes were confirmed using fluorescent in situ hybridization. Most importantly, we observed axonal mistargeting in knockouts of three candidate axonal guidance genes identified in this analysis: nrp1a, nrp1b, and robo2. In each case, targeting errors were detected in the subset of axons that normally express these transcripts at high levels, and not in the axons that express them at low levels. Our findings demonstrate that specific, functional, axonal guidance related genes are expressed in subsets of OSNs that that can be categorized by their patterns of OR expression.

Dataset Information

Assaying sensory ciliopathies using calcium biosensor expression in zebrafish ciliated olfactory neurons.

Background

Methods

Results

Conclusions

Publications

Assaying sensory ciliopathies using calcium biosensor expression in zebrafish ciliated olfactory neurons.

Similar Datasets

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