Abstract

We recently reported that the C2AB portion of Synaptotagmin 1 (Syt1) could self-assemble into Ca2+-sensitive ring-like oligomers on membranes, which could potentially regulate neurotransmitter release. Here we report that analogous ring-like oligomers assemble from the C2AB domains of other Syt isoforms (Syt2, Syt7, Syt9) as well as related C2 domain containing protein, Doc2B and extended Synaptotagmins (E-Syts). Evidently, circular oligomerization is a general and conserved structural aspect of many C2 domain proteins, including Synaptotagmins. Further, using electron microscopy combined with targeted mutations, we show that under physiologically relevant conditions, both the Syt1 ring assembly and its rapid disruption by Ca2+ involve the well-established functional surfaces on the C2B domain that are important for synaptic transmission. Our data suggests that ring formation may be triggered at an early step in synaptic vesicle docking and positions Syt1 to synchronize neurotransmitter release to Ca2+ influx.

Article and author information

Author details

  1. Maria N Zanetti

    Department of Cell Biology, Yale School of Medicine, New Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Oscar D Bello

    Department of Cell Biology, Yale School of Medicine, New Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Jing Wang

    Department of Cell Biology, Yale School of Medicine, New Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Jeff Coleman

    Department of Cell Biology, Yale School of Medicine, New Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Yiying Cai

    Department of Cell Biology, Yale School of Medicine, New Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Charles V Sindelar

    Department of Molecular Biophysics and Biochemistry, Yale School of Medicine, New Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  7. James E Rothman

    Department of Cell Biology, Yale School of Medicine, New Haven, United States
    For correspondence
    james.rothman@yale.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-8653-8650
  8. Shyam S Krishnakumar

    Department of Cell Biology, Yale School of Medicine, New Haven, United States
    For correspondence
    shyam.krishnakumar@yale.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-6148-3251

Funding

National Institute of General Medical Sciences (GM071458)

  • James E Rothman

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

© 2016, Zanetti et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

Download links

Share this article

https://doi.org/10.7554/eLife.17262

Further reading

    1. Neuroscience
    2. Physics of Living Systems
    Moritz Schloetter, Georg U Maret, Christoph J Kleineidam
    Research Article

    Neurons generate and propagate electrical pulses called action potentials which annihilate on arrival at the axon terminal. We measure the extracellular electric field generated by propagating and annihilating action potentials and find that on annihilation, action potentials expel a local discharge. The discharge at the axon terminal generates an inhomogeneous electric field that immediately influences target neurons and thus provokes ephaptic coupling. Our measurements are quantitatively verified by a powerful analytical model which reveals excitation and inhibition in target neurons, depending on position and morphology of the source-target arrangement. Our model is in full agreement with experimental findings on ephaptic coupling at the well-studied Basket cell-Purkinje cell synapse. It is able to predict ephaptic coupling for any other synaptic geometry as illustrated by a few examples.

    1. Neuroscience
    Ulrike Pech, Jasper Janssens ... Patrik Verstreken
    Research Article

    The classical diagnosis of Parkinsonism is based on motor symptoms that are the consequence of nigrostriatal pathway dysfunction and reduced dopaminergic output. However, a decade prior to the emergence of motor issues, patients frequently experience non-motor symptoms, such as a reduced sense of smell (hyposmia). The cellular and molecular bases for these early defects remain enigmatic. To explore this, we developed a new collection of five fruit fly models of familial Parkinsonism and conducted single-cell RNA sequencing on young brains of these models. Interestingly, cholinergic projection neurons are the most vulnerable cells, and genes associated with presynaptic function are the most deregulated. Additional single nucleus sequencing of three specific brain regions of Parkinson’s disease patients confirms these findings. Indeed, the disturbances lead to early synaptic dysfunction, notably affecting cholinergic olfactory projection neurons crucial for olfactory function in flies. Correcting these defects specifically in olfactory cholinergic interneurons in flies or inducing cholinergic signaling in Parkinson mutant human induced dopaminergic neurons in vitro using nicotine, both rescue age-dependent dopaminergic neuron decline. Hence, our research uncovers that one of the earliest indicators of disease in five different models of familial Parkinsonism is synaptic dysfunction in higher-order cholinergic projection neurons and this contributes to the development of hyposmia. Furthermore, the shared pathways of synaptic failure in these cholinergic neurons ultimately contribute to dopaminergic dysfunction later in life.