| Abstract No.: | C-B3057 |
| Country: | Canada |
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| Title: | STRUCTURAL PLASTICITY OF THE ACTIVE ZONE CYTOMATRIX AT SYNAPSES BETWEEN HIPPOCAMPAL NEURONS |
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| Authors/Affiliations: | 2 Annette Kolar1, 3Zachary Anaya, 1,2 Stefan R. Krueger
1 Dalhousie University, 1Dept. of Physiology and Biophysics, 2Neuroscience Institute, and 3Undergraduate Neuroscience Program, Halifax, NS, Canada
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| Content: | Objectives: Many studies have highlighted the structural plasticity of postsynaptic densities at glutamatergic synapses and emphasized its importance in conferring long-term changes of the synaptic efficacy at these connections. In contrast, relatively little is known about any structural alterations at presynaptic specializations that may accompany these postsynaptic changes. Our study addresses whether similar structural rearrangements of the presynaptic active zone cytomatrix occur and determines their effect on synaptic transmission.
Materials and Methods: We have tagged two proteins of the active zone cytomatrix (CAZ), bassoon and RIM1, with the fluorescent proteins mCherry and EGFP to assess the stability of active zones at synapses of hippocampal neurons in culture, and are utilizing a genetically encoded fluorescent sensor of synaptic vesicle turnover, synaptophysin-pHluorin, to study the functional consequences of any structural changes observed.
Results: We find that the active zones are very dynamic in young cultures, and remain subject to structural alterations in older cultures. Clusters of CAZ material are often mobilized from active zones, transported within the axon, and deposited at adjacent synapses. CAZ clusters are frequently, but not always co-mobilized with associated synaptic vesicle clusters. We are currently investigating the functional consequences of the observed changes in size of active zones and associated synaptic vesicle pools, hypothesizing that these structural rearrangements cause sustained changes in the probability of neurotransmitter release at synapses.
Conclusion: Our study demonstrates that, similar to postsynaptic specializations at glutamatergic synapses, active zones undergo large-scale structural changes that may elicit long-term alterations in the efficacy of neurotransmitter release and thus synaptic transmission.
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