| Abstract No.: | A-A1010 |
| Country: | Canada |
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| Title: | 14-3-3 PROTEINS AND GROWTH CONE DYNAMICS |
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| Authors/Affiliations: | 1 Chris Kent*; 1 Alyson E. Fournier;
1 Montreal Neurological Institute, QC, Canada
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| Content: | Background: The distal tip of a developing axon, termed the growth cone, is a highly regulated dynamic structure, critical to establishing the proper speed and direction of neuronal outgrowth. This structure must integrate responses to numerous cues through precise spatial regulation of the dynamic actin and microtubule cytoskeleton. An initial proteomics screen of growth cones found members of the 14-3-3 adaptor protein family present. These proteins regulate a wide variety of Serine/Threonine phosphorylated targets in diverse cell mechanisms such as cell-cycle control, apoptosis, sub-cellular localization and cytoskeletal reorganization. 14-3-3s have previously been implicated in modulating the activity of Serine/Threonine Kinases and Phosphatases known to be involved in the regulation of actin dynamics. Together with their presence in growth cones, this suggests that 14-3-3 proteins could play an important role in modulating cytoskeletal dynamics in response various cues.
Objective: To establish the role of 14-3-3 proteins in growth cone dynamics and test the hypothesis that 14-3-3 proteins could be integration points in growth cones allowing multiple ligand effects to be properly coordinated at the level of cytoskeleton dynamics.
Materials and Methods: Immunocytochemistry was used to characterize the expression of multiple 14-3-3 isoforms within growth cones of different cell types and developmental time points. Live cell fluorescent imaging was used in conjunction with filopodial tracking software and kymographs to assess the impact of the 14-3-3 binding inhibitor R18 peptide on the structural dynamics of growth cones. Immunoprecipitation experiments were used to examine the regulation of 14-3-3 binding in response to ligands known to act as guidance cues.
Results: We show that 14-3-3 isoform expression is both developmentally regulated and cell-type specific. Knockdown of 14-3-3 binding alters the dynamics of lamellapodial structures without effecting filopodial behaviour and this in turn diminishes basal neurite outgrowth.
Conclusions: We propose that 14-3-3 proteins play a role in modulating the dynamic behaviour of growth cone structures and may be involved in regulating the response to guidance cues through altering the interaction between receptors and downstream effector molecules.
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