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Updated: Nov 15, 2025
Detection of Axonally Localized mRNAs in Brain Sections Using High-Resolution In Situ Hybridization
Published on: June 17, 2015
Selective axonal translation of the mRNA isoform encoding prenylated Cdc42 supports axon growth
Seung Joon Lee1, Matthew D Zdradzinski1, Pabitra K Sahoo1
1Department of Biological Sciences, University of South Carolina, Columbia, SC 29208USA.
Abstract:
The small Rho-family GTPase Cdc42 has long been known to have a role in cell motility and axon growth. The eukaryotic Ccd42 gene is alternatively spliced to generate mRNAs with two different 3' untranslated regions (UTRs) that encode proteins with distinct C-termini. The C-termini of these Cdc42 proteins include CaaX and CCaX motifs for post-translational prenylation and palmitoylation, respectively. Palmitoyl-Cdc42 protein was previously shown to contribute to dendrite maturation, while the prenyl-Cdc42 protein contributes to axon specification and its mRNA was detected in neurites. Here, we show that the mRNA encoding prenyl-Cdc42 isoform preferentially localizes into PNS axons and this localization selectively increases in vivo during peripheral nervous system (PNS) axon regeneration. Functional studies indicate that prenyl-Cdc42 increases axon length in a manner that requires axonal targeting of its mRNA, which, in turn, needs an intact C-terminal CaaX motif that can drive prenylation of the encoded protein. In contrast, palmitoyl-Cdc42 has no effect on axon growth but selectively increases dendrite length. Together, these data show that alternative splicing of the Cdc42 gene product generates an axon growth promoting, locally synthesized prenyl-Cdc42 protein. This article has an associated First Person interview with one of the co-first authors of the paper.
Insights
The Cdc42 gene
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Biology
Background:
- Cdc42, a Rho-family GTPase, is crucial for cell motility and axon growth.
- Alternative splicing of the Cdc42 gene generates two mRNA variants with distinct C-termini and functions.
- These C-termini contain CaaX and CCaX motifs, mediating prenylation and palmitoylation, respectively.
Purpose of the Study:
- To investigate the distinct roles of Cdc42 protein isoforms in neuronal development and regeneration.
- To determine the localization and function of prenyl-Cdc42 mRNA in peripheral nervous system (PNS) axons.
- To elucidate the mechanisms underlying prenyl-Cdc42's contribution to axon growth.
Main Methods:
- Analysis of mRNA localization in PNS axons.
- In vivo studies of axon regeneration in the PNS.
- Functional assays assessing axon and dendrite growth.
- Investigation of the role of the C-terminal CaaX motif and prenylation.
Main Results:
- mRNA encoding prenyl-Cdc42 preferentially localizes to PNS axons and increases during regeneration.
- Prenyl-Cdc42 enhances axon length, dependent on mRNA axonal targeting and CaaX motif-driven prenylation.
- Palmitoyl-Cdc42 selectively promotes dendrite length but does not affect axon growth.
Conclusions:
- Alternative splicing of Cdc42 generates a prenyl-Cdc42 protein that promotes axon growth through local synthesis.
- Axonal targeting of prenyl-Cdc42 mRNA is essential for its role in axon elongation.
- Distinct Cdc42 isoforms differentially regulate axon and dendrite development.
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