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Correlated Levels of mRNA and Soma Size in Single Identified Neurons: Evidence for Compartment-specific Regulation of Gene Expression.

Ransdell JL, Faust TB, Schulz DJ - Front Mol Neurosci (2010)

Bottom Line: Levels of mRNA for the K+ channel shal, which is localized exclusively to the soma, are negatively correlated with soma size, suggesting that gene expression does not simply track positively with compartment size.Conversely, levels of beta-actin and beta-tubulin mRNA, which are major cytoskeletal proteins of neuronal processes, do not correlate with soma size, but are strongly correlated with one another.These results suggest that steady-state transcript levels are differentially regulated based on the subcellular compartment within which a given gene product primarily acts.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Missouri Columbia Columbia, MO, USA.

ABSTRACT
In addition to the overall complexity of transcriptional regulation, cells also must take into account the subcellular distribution of these gene products. This is particularly challenging for morphologically complex cells such as neurons. Yet the interaction between cellular morphology and gene expression is poorly understood. Here we provide some of the first evidence for a relationship between neuronal compartment size and maintenance of mRNA levels in neurons. We find that single-cell transcript levels of 18S rRNA, GAPDH, and EF1-alpha, all gene products with primary functions in the cell soma, are strongly correlated to soma size in multiple distinct neuronal types. Levels of mRNA for the K+ channel shal, which is localized exclusively to the soma, are negatively correlated with soma size, suggesting that gene expression does not simply track positively with compartment size. Conversely, levels of beta-actin and beta-tubulin mRNA, which are major cytoskeletal proteins of neuronal processes, do not correlate with soma size, but are strongly correlated with one another. Additionally, actin/tubulin expression levels correlate with voltage-gated ion channels that are uniquely localized to axons. These results suggest that steady-state transcript levels are differentially regulated based on the subcellular compartment within which a given gene product primarily acts.

No MeSH data available.


Related in: MedlinePlus

Mean ± SEM of the relative soma size (A) and levels of expression of five different genes (B – F) in identified neurons of the STG. Sample size indicated in each bar. P-values reported are the results of one-way ANOVA analyses for each gene. Individual cell types are listed on the x-axis.
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Figure 2: Mean ± SEM of the relative soma size (A) and levels of expression of five different genes (B – F) in identified neurons of the STG. Sample size indicated in each bar. P-values reported are the results of one-way ANOVA analyses for each gene. Individual cell types are listed on the x-axis.

Mentions: To ensure that measurements of soma area were not affected by differences in mounting of the preparation, the neuronal soma area of each identified cell was normalized to a PD cell soma area within that ganglion. This soma size is expressed as a relative measure with PD values set to 1.0. Measured in this way the STG cells showed significant differences in their somata areas among cell types (p < 0.001, ANOVA). Mean cell somata sizes ranked from largest to smallest as follows: LG > LP > PD > IC > LPG > PY (Figure 2A). LG neurons were consistently the largest neuron in a given ganglion, with a mean size approximately 135% of that of PD. Conversely, PY cells were consistently the smallest in a given ganglion, measuring approximately 60% the size of PD cells and less than half the size of LG.


Correlated Levels of mRNA and Soma Size in Single Identified Neurons: Evidence for Compartment-specific Regulation of Gene Expression.

Ransdell JL, Faust TB, Schulz DJ - Front Mol Neurosci (2010)

Mean ± SEM of the relative soma size (A) and levels of expression of five different genes (B – F) in identified neurons of the STG. Sample size indicated in each bar. P-values reported are the results of one-way ANOVA analyses for each gene. Individual cell types are listed on the x-axis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2991126&req=5

Figure 2: Mean ± SEM of the relative soma size (A) and levels of expression of five different genes (B – F) in identified neurons of the STG. Sample size indicated in each bar. P-values reported are the results of one-way ANOVA analyses for each gene. Individual cell types are listed on the x-axis.
Mentions: To ensure that measurements of soma area were not affected by differences in mounting of the preparation, the neuronal soma area of each identified cell was normalized to a PD cell soma area within that ganglion. This soma size is expressed as a relative measure with PD values set to 1.0. Measured in this way the STG cells showed significant differences in their somata areas among cell types (p < 0.001, ANOVA). Mean cell somata sizes ranked from largest to smallest as follows: LG > LP > PD > IC > LPG > PY (Figure 2A). LG neurons were consistently the largest neuron in a given ganglion, with a mean size approximately 135% of that of PD. Conversely, PY cells were consistently the smallest in a given ganglion, measuring approximately 60% the size of PD cells and less than half the size of LG.

Bottom Line: Levels of mRNA for the K+ channel shal, which is localized exclusively to the soma, are negatively correlated with soma size, suggesting that gene expression does not simply track positively with compartment size.Conversely, levels of beta-actin and beta-tubulin mRNA, which are major cytoskeletal proteins of neuronal processes, do not correlate with soma size, but are strongly correlated with one another.These results suggest that steady-state transcript levels are differentially regulated based on the subcellular compartment within which a given gene product primarily acts.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Missouri Columbia Columbia, MO, USA.

ABSTRACT
In addition to the overall complexity of transcriptional regulation, cells also must take into account the subcellular distribution of these gene products. This is particularly challenging for morphologically complex cells such as neurons. Yet the interaction between cellular morphology and gene expression is poorly understood. Here we provide some of the first evidence for a relationship between neuronal compartment size and maintenance of mRNA levels in neurons. We find that single-cell transcript levels of 18S rRNA, GAPDH, and EF1-alpha, all gene products with primary functions in the cell soma, are strongly correlated to soma size in multiple distinct neuronal types. Levels of mRNA for the K+ channel shal, which is localized exclusively to the soma, are negatively correlated with soma size, suggesting that gene expression does not simply track positively with compartment size. Conversely, levels of beta-actin and beta-tubulin mRNA, which are major cytoskeletal proteins of neuronal processes, do not correlate with soma size, but are strongly correlated with one another. Additionally, actin/tubulin expression levels correlate with voltage-gated ion channels that are uniquely localized to axons. These results suggest that steady-state transcript levels are differentially regulated based on the subcellular compartment within which a given gene product primarily acts.

No MeSH data available.


Related in: MedlinePlus