Synaptic vesicle proteins are selectively delivered to axons in mammalian neurons
Neurotransmitter-filled synaptic vesicles (SVs) mediate synaptic transmission and are a hallmark specialization in neuronal axons. Yet, how SV proteins are sorted to presynaptic nerve terminals remains the subject of debate. The leading model posits that these proteins are randomly trafficked throug...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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eLife Sciences Publications Ltd
2023-02-01
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| Series: | eLife |
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| Online Access: | https://elifesciences.org/articles/82568 |
| _version_ | 1797934599382237184 |
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| author | Emma T Watson Michaela M Pauers Michael J Seibert Jason D Vevea Edwin R Chapman |
| author_facet | Emma T Watson Michaela M Pauers Michael J Seibert Jason D Vevea Edwin R Chapman |
| author_sort | Emma T Watson |
| collection | DOAJ |
| description | Neurotransmitter-filled synaptic vesicles (SVs) mediate synaptic transmission and are a hallmark specialization in neuronal axons. Yet, how SV proteins are sorted to presynaptic nerve terminals remains the subject of debate. The leading model posits that these proteins are randomly trafficked throughout neurons and are selectively retained in presynaptic boutons. Here, we used the RUSH (retention using selective hooks) system, in conjunction with HaloTag labeling approaches, to study the egress of two distinct transmembrane SV proteins, synaptotagmin 1 and synaptobrevin 2, from the soma of mature cultured rat and mouse neurons. For these studies, the SV reporter constructs were expressed at carefully controlled, very low levels. In sharp contrast to the selective retention model, both proteins selectively and specifically entered axons with minimal entry into dendrites. However, even moderate overexpression resulted in the spillover of SV proteins into dendrites, potentially explaining the origin of previous non-polarized transport models, revealing the limited, saturable nature of the direct axonal trafficking pathway. Moreover, we observed that SV constituents were first delivered to the presynaptic plasma membrane before incorporation into SVs. These experiments reveal a new-found membrane trafficking pathway, for SV proteins, in classically polarized mammalian neurons and provide a glimpse at the first steps of SV biogenesis. |
| first_indexed | 2024-04-10T18:01:32Z |
| format | Article |
| id | doaj.art-4b905ba3ddf448e3bff0358ebfd55eef |
| institution | Directory Open Access Journal |
| issn | 2050-084X |
| language | English |
| last_indexed | 2024-04-10T18:01:32Z |
| publishDate | 2023-02-01 |
| publisher | eLife Sciences Publications Ltd |
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| spelling | doaj.art-4b905ba3ddf448e3bff0358ebfd55eef2023-02-02T15:19:01ZengeLife Sciences Publications LtdeLife2050-084X2023-02-011210.7554/eLife.82568Synaptic vesicle proteins are selectively delivered to axons in mammalian neuronsEmma T Watson0https://orcid.org/0000-0002-5336-8170Michaela M Pauers1https://orcid.org/0000-0001-9760-7041Michael J Seibert2https://orcid.org/0000-0003-1619-1852Jason D Vevea3https://orcid.org/0000-0002-3068-973XEdwin R Chapman4https://orcid.org/0000-0001-9787-8140Department of Neuroscience, University of Wisconsin-Madison, Madison, United States; Howard Hughes Medical Institute, Madison, United StatesDepartment of Neuroscience, University of Wisconsin-Madison, Madison, United States; Howard Hughes Medical Institute, Madison, United StatesDepartment of Neuroscience, University of Wisconsin-Madison, Madison, United States; Howard Hughes Medical Institute, Madison, United StatesDepartment of Neuroscience, University of Wisconsin-Madison, Madison, United States; Howard Hughes Medical Institute, Madison, United StatesDepartment of Neuroscience, University of Wisconsin-Madison, Madison, United States; Howard Hughes Medical Institute, Madison, United StatesNeurotransmitter-filled synaptic vesicles (SVs) mediate synaptic transmission and are a hallmark specialization in neuronal axons. Yet, how SV proteins are sorted to presynaptic nerve terminals remains the subject of debate. The leading model posits that these proteins are randomly trafficked throughout neurons and are selectively retained in presynaptic boutons. Here, we used the RUSH (retention using selective hooks) system, in conjunction with HaloTag labeling approaches, to study the egress of two distinct transmembrane SV proteins, synaptotagmin 1 and synaptobrevin 2, from the soma of mature cultured rat and mouse neurons. For these studies, the SV reporter constructs were expressed at carefully controlled, very low levels. In sharp contrast to the selective retention model, both proteins selectively and specifically entered axons with minimal entry into dendrites. However, even moderate overexpression resulted in the spillover of SV proteins into dendrites, potentially explaining the origin of previous non-polarized transport models, revealing the limited, saturable nature of the direct axonal trafficking pathway. Moreover, we observed that SV constituents were first delivered to the presynaptic plasma membrane before incorporation into SVs. These experiments reveal a new-found membrane trafficking pathway, for SV proteins, in classically polarized mammalian neurons and provide a glimpse at the first steps of SV biogenesis.https://elifesciences.org/articles/82568axonal transportsynaptobrevinpolaritysynaptic vesicleHaloTagsynaptotagmin |
| spellingShingle | Emma T Watson Michaela M Pauers Michael J Seibert Jason D Vevea Edwin R Chapman Synaptic vesicle proteins are selectively delivered to axons in mammalian neurons eLife axonal transport synaptobrevin polarity synaptic vesicle HaloTag synaptotagmin |
| title | Synaptic vesicle proteins are selectively delivered to axons in mammalian neurons |
| title_full | Synaptic vesicle proteins are selectively delivered to axons in mammalian neurons |
| title_fullStr | Synaptic vesicle proteins are selectively delivered to axons in mammalian neurons |
| title_full_unstemmed | Synaptic vesicle proteins are selectively delivered to axons in mammalian neurons |
| title_short | Synaptic vesicle proteins are selectively delivered to axons in mammalian neurons |
| title_sort | synaptic vesicle proteins are selectively delivered to axons in mammalian neurons |
| topic | axonal transport synaptobrevin polarity synaptic vesicle HaloTag synaptotagmin |
| url | https://elifesciences.org/articles/82568 |
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