| Abstract No.: | C-A3015 |
| Country: | Canada |
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| Title: | LOCALIZATION AND TRAFFICKING OF FXR1PD IN HIPPOCAMPAL NEURONS
DENISE COOK, CLAUDE LACHANCE, DANUTA RADZIOCH, KEITH K. MURAI
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| Authors/Affiliations: | 1 Denise Cook*; 1 Claude Lachance; 1 Danuta Radzioch; 1 Keith Murai;
1 McGill University, Montreal, QC, Canada
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| Content: | Objectives: Fragile X Related Protein 1 (FXR1P) is a member of a trio of RNA binding proteins that is implicated in posttranscriptional regulation of mRNAs. All three fragile X family members, which also includes FMRP and FXR2, are expressed in the mammalian brain and have highly similar N-termini (70% similarity) but diverge significantly in their C-termini (6% similarity). FXR1P exists in seven alternatively spliced isoforms which are differentially expressed in various tissues, with isoforms a-d expressed in mammalian brain. We are interested in the localization, trafficking and function of FXR1d in hippocampal neurons from mouse brain. Materials and Methods: Using a combination of biochemical and culture techniques, we investigated the expression and subcellular localization of endogenous and overexpressed FXR1P. Results: We have shown that FXR1Pd expression is enhanced during early postnatal development (P5-P21) of the hippocampus and diminishes in adulthood, suggestive of a role in dendritic spine development or synaptic plasticity. In order to investigate the targeting of this protein in hippocampal neurons, we generated a Semliki Forest Virus to overexpress EGFP-FXR1Pd in combination with membrane-targeted mCherry. This virus was used to infect CA1 pyramidal neurons in hippocampal organotypic slice culture to follow the localization of EGFP-FXR1d using static and time-lapse confocal imaging. EGFP-FXR1d was found to be enriched in the somatodendritic compartment where it forms heterogeneous sized clusters in approximately 50% of CA1 cells. In the other 50% of cells, EGFP-FXR1d is diffusely distributed throughout the dendritic cytoplasm. Surprisingly, the majority of these clusters were shown to be non-motile over periods of up to one hour. Conclusion: These results suggest that FXR1d is expressed during hippocampal development and may have differential roles in regulating dendritic mRNAs. |
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