Regulation of presynaptic Ca2+ channel abundance at active zones through a balance of delivery and turnover
<jats:p>Voltage-gated Ca<jats:sup>2+</jats:sup> channels (VGCCs) mediate Ca<jats:sup>2+</jats:sup> influx to trigger neurotransmitter release at specialized presynaptic sites termed active zones (AZs). The abundance of VGCCs at AZs regulates neurotransmitter release pro...
| Main Authors: | , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
eLife Sciences Publications, Ltd
2022
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| Online Access: | https://hdl.handle.net/1721.1/146889 |
| _version_ | 1826189723840806912 |
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| author | Cunningham, Karen L Sauvola, Chad W Tavana, Sara Littleton, J Troy |
| author2 | Massachusetts Institute of Technology. Department of Biology |
| author_facet | Massachusetts Institute of Technology. Department of Biology Cunningham, Karen L Sauvola, Chad W Tavana, Sara Littleton, J Troy |
| author_sort | Cunningham, Karen L |
| collection | MIT |
| description | <jats:p>Voltage-gated Ca<jats:sup>2+</jats:sup> channels (VGCCs) mediate Ca<jats:sup>2+</jats:sup> influx to trigger neurotransmitter release at specialized presynaptic sites termed active zones (AZs). The abundance of VGCCs at AZs regulates neurotransmitter release probability (<jats:italic>P<jats:sub>r</jats:sub></jats:italic>), a key presynaptic determinant of synaptic strength. Although biosynthesis, delivery, and recycling cooperate to establish AZ VGCC abundance, experimentally isolating these distinct regulatory processes has been difficult. Here, we describe how the AZ levels of cacophony (Cac), the sole VGCC-mediating synaptic transmission in <jats:italic>Drosophila</jats:italic>, are determined. We also analyzed the relationship between Cac, the conserved VGCC regulatory subunit α2δ, and the core AZ scaffold protein Bruchpilot (BRP) in establishing a functional AZ. We find that Cac and BRP are independently regulated at growing AZs, as Cac is dispensable for AZ formation and structural maturation, and BRP abundance is not limiting for Cac accumulation. Additionally, AZs stop accumulating Cac after an initial growth phase, whereas BRP levels continue to increase given extended developmental time. AZ Cac is also buffered against moderate increases or decreases in biosynthesis, whereas BRP lacks this buffering. To probe mechanisms that determine AZ Cac abundance, intravital FRAP and Cac photoconversion were used to separately measure delivery and turnover at individual AZs over a multi-day period. Cac delivery occurs broadly across the AZ population, correlates with AZ size, and is rate-limited by α2δ. Although Cac does not undergo significant lateral transfer between neighboring AZs over the course of development, Cac removal from AZs does occur and is promoted by new Cac delivery, generating a cap on Cac accumulation at mature AZs. Together, these findings reveal how Cac biosynthesis, synaptic delivery, and recycling set the abundance of VGCCs at individual AZs throughout synapse development and maintenance.</jats:p> |
| first_indexed | 2024-09-23T08:20:02Z |
| format | Article |
| id | mit-1721.1/146889 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T08:20:02Z |
| publishDate | 2022 |
| publisher | eLife Sciences Publications, Ltd |
| record_format | dspace |
| spelling | mit-1721.1/1468892022-12-16T03:48:18Z Regulation of presynaptic Ca2+ channel abundance at active zones through a balance of delivery and turnover Cunningham, Karen L Sauvola, Chad W Tavana, Sara Littleton, J Troy Massachusetts Institute of Technology. Department of Biology <jats:p>Voltage-gated Ca<jats:sup>2+</jats:sup> channels (VGCCs) mediate Ca<jats:sup>2+</jats:sup> influx to trigger neurotransmitter release at specialized presynaptic sites termed active zones (AZs). The abundance of VGCCs at AZs regulates neurotransmitter release probability (<jats:italic>P<jats:sub>r</jats:sub></jats:italic>), a key presynaptic determinant of synaptic strength. Although biosynthesis, delivery, and recycling cooperate to establish AZ VGCC abundance, experimentally isolating these distinct regulatory processes has been difficult. Here, we describe how the AZ levels of cacophony (Cac), the sole VGCC-mediating synaptic transmission in <jats:italic>Drosophila</jats:italic>, are determined. We also analyzed the relationship between Cac, the conserved VGCC regulatory subunit α2δ, and the core AZ scaffold protein Bruchpilot (BRP) in establishing a functional AZ. We find that Cac and BRP are independently regulated at growing AZs, as Cac is dispensable for AZ formation and structural maturation, and BRP abundance is not limiting for Cac accumulation. Additionally, AZs stop accumulating Cac after an initial growth phase, whereas BRP levels continue to increase given extended developmental time. AZ Cac is also buffered against moderate increases or decreases in biosynthesis, whereas BRP lacks this buffering. To probe mechanisms that determine AZ Cac abundance, intravital FRAP and Cac photoconversion were used to separately measure delivery and turnover at individual AZs over a multi-day period. Cac delivery occurs broadly across the AZ population, correlates with AZ size, and is rate-limited by α2δ. Although Cac does not undergo significant lateral transfer between neighboring AZs over the course of development, Cac removal from AZs does occur and is promoted by new Cac delivery, generating a cap on Cac accumulation at mature AZs. Together, these findings reveal how Cac biosynthesis, synaptic delivery, and recycling set the abundance of VGCCs at individual AZs throughout synapse development and maintenance.</jats:p> 2022-12-15T18:18:12Z 2022-12-15T18:18:12Z 2022 2022-12-15T17:51:36Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/146889 Cunningham, Karen L, Sauvola, Chad W, Tavana, Sara and Littleton, J Troy. 2022. "Regulation of presynaptic Ca2+ channel abundance at active zones through a balance of delivery and turnover." eLife, 11. en 10.7554/ELIFE.78648 eLife Creative Commons Attribution 4.0 International license https://creativecommons.org/licenses/by/4.0/ application/pdf eLife Sciences Publications, Ltd eLife |
| spellingShingle | Cunningham, Karen L Sauvola, Chad W Tavana, Sara Littleton, J Troy Regulation of presynaptic Ca2+ channel abundance at active zones through a balance of delivery and turnover |
| title | Regulation of presynaptic Ca2+ channel abundance at active zones through a balance of delivery and turnover |
| title_full | Regulation of presynaptic Ca2+ channel abundance at active zones through a balance of delivery and turnover |
| title_fullStr | Regulation of presynaptic Ca2+ channel abundance at active zones through a balance of delivery and turnover |
| title_full_unstemmed | Regulation of presynaptic Ca2+ channel abundance at active zones through a balance of delivery and turnover |
| title_short | Regulation of presynaptic Ca2+ channel abundance at active zones through a balance of delivery and turnover |
| title_sort | regulation of presynaptic ca2 channel abundance at active zones through a balance of delivery and turnover |
| url | https://hdl.handle.net/1721.1/146889 |
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