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Alteration of genic 5-hydroxymethylcytosine patterning in olfactory neurons correlates with changes in gene expression and cell identity.

ABSTRACT: The modified DNA base 5-hydroxymethylcytosine (5hmC) is enriched in neurons where it may contribute to gene regulation and cellular identity. To determine how 5hmC influences gene expression in an in vivo neuronal population, we assessed the patterning and function of the base along the developmental lineage of the main olfactory epithelium-from multipotent stem cells through neuronal progenitors to mature olfactory sensory neurons (mOSNs). We find that 5hmC increases over gene bodies during mOSN development with substantial patterning occuring between the progenitor and mOSN stages. Although gene-body 5hmC levels correlate with gene expression in all three developmental cell types, this association is particularly pronounced within mOSNs. Overexpression of Tet3 in mOSNs markedly alters gene-body 5hmC levels and gene expression in a manner consistent with a positive role for 5hmC in transcription. Moreover, Tet3 overexpression disrupts olfactory receptor expression and the targeting of axons to the olfactory bulb, key molecular and anatomical features of the olfactory system. Our results suggest a physiologically significant role for gene-body 5hmC in transcriptional facilitation and the maintenance of cellular identity independent of its function as an intermediate to demethylation.

SUBMITTER: Colquitt BM

PROVIDER: S-EPMC3767503 | biostudies-literature | 2013 Sep

REPOSITORIES: biostudies-literature

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Alteration of genic 5-hydroxymethylcytosine patterning in olfactory neurons correlates with changes in gene expression and cell identity.

Colquitt Bradley M BM Allen William E WE Barnea Gilad G Lomvardas Stavros S

Proceedings of the National Academy of Sciences of the United States of America 20130822 36

The modified DNA base 5-hydroxymethylcytosine (5hmC) is enriched in neurons where it may contribute to gene regulation and cellular identity. To determine how 5hmC influences gene expression in an in vivo neuronal population, we assessed the patterning and function of the base along the developmental lineage of the main olfactory epithelium-from multipotent stem cells through neuronal progenitors to mature olfactory sensory neurons (mOSNs). We find that 5hmC increases over gene bodies during mOS ...[more]

PMID: 23969834

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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

Alteration of genic 5-hydroxymethylcytosine patterning in olfactory neurons correlates with changes in gene expression and cell identity.

Publications

Alteration of genic 5-hydroxymethylcytosine patterning in olfactory neurons correlates with changes in gene expression and cell identity.

Similar Datasets

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