Abstract

The molecular mechanisms underlying the diversity of cortical glutamatergic synapses is still incompletely understood. Here, we tested the hypothesis that presynaptic active zones (AZs) are constructed from molecularly uniform, independent release sites (RSs), the number of which scales linearly with the AZ size. Paired recordings between hippocampal CA1 pyramidal cells and fast-spiking interneurons in acute slices from adult mice followed by quantal analysis demonstrate large variability in the number of RSs (N) at these connections. High resolution molecular analysis of functionally characterized synapses reveals variability in the content of one of the key vesicle priming factors – Munc13-1 – in AZs that possess the same N. Replica immunolabeling also shows a 3-fold variability in the total Munc13-1 content of AZs of identical size, and a 4-fold variability in the size and density of Munc13-1 clusters within the AZs. Our results provide evidence for quantitative molecular heterogeneity of RSs and support a model in which the AZ is built up from variable numbers of molecularly heterogeneous, but independent RSs.

Data availability

Source data have been provided for all figures.

Article and author information

Author details

  1. Maria Rita Karlocai

    Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest, Hungary
    Competing interests
    The authors declare that no competing interests exist.
  2. Judit Heredi

    Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest, Hungary
    Competing interests
    The authors declare that no competing interests exist.
  3. Tünde Benedek

    Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest, Hungary
    Competing interests
    The authors declare that no competing interests exist.
  4. Noemi Holderith

    Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest, Hungary
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-0024-3980
  5. Andrea Lorincz

    Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest, Hungary
    Competing interests
    The authors declare that no competing interests exist.
  6. Zoltan Nusser

    Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest, Hungary
    For correspondence
    nusser.zoltan@koki.mta.hu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7004-4111

Funding

European Research Council (ERC-AG 787157)

  • Zoltan Nusser

Hungarian National Brain Research grant

  • Zoltan Nusser

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

Ethics

Animal experimentation: All the experiments were carried out according to the regulations of the Hungarian Act of Animal Care and Experimentation 40/2013 (II.14) and were reviewed and approved by the Animal Committee of the Institute of Experimental Medicine, Budapest.

Copyright

© 2021, Karlocai 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.

Metrics

  • 1,737
    views
  • 315
    downloads
  • 34
    citations

Views, downloads and citations are aggregated across all versions of this paper published by eLife.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Maria Rita Karlocai
  2. Judit Heredi
  3. Tünde Benedek
  4. Noemi Holderith
  5. Andrea Lorincz
  6. Zoltan Nusser
(2021)
Variability in the Munc13-1 content of excitatory release site
eLife 10:e67468.
https://doi.org/10.7554/eLife.67468

Share this article

https://doi.org/10.7554/eLife.67468

Further reading

    1. Neuroscience
    Kaspar E Vogt, Ashwinikumar Kulkarni ... Robert W Greene
    Research Article

    Sleep loss increases AMPA-synaptic strength and number in the neocortex. However, this is only part of the synaptic sleep loss response. We report an increased AMPA/NMDA EPSC ratio in frontal-cortical pyramidal neurons of layers 2–3. Silent synapses are absent, decreasing the plastic potential to convert silent NMDA to active AMPA synapses. These sleep loss changes are recovered by sleep. Sleep genes are enriched for synaptic shaping cellular components controlling glutamate synapse phenotype, overlap with autism risk genes, and are primarily observed in excitatory pyramidal neurons projecting intra-telencephalically. These genes are enriched with genes controlled by the transcription factor, MEF2c, and its repressor, HDAC4. Sleep genes can thus provide a framework within which motor learning and training occur mediated by the sleep-dependent oscillation of glutamate-synaptic phenotypes.

    1. Neuroscience
    Hans Auer, Donna Gift Cabalo ... Jessica Royer
    Research Article

    The amygdala is a subcortical region in the mesiotemporal lobe that plays a key role in emotional and sensory functions. Conventional neuroimaging experiments treat this structure as a single, uniform entity, but there is ample histological evidence for subregional heterogeneity in microstructure and function. The current study characterized subregional structure-function coupling in the human amygdala, integrating post-mortem histology and in vivo MRI at ultra-high fields. Core to our work was a novel neuroinformatics approach that leveraged multiscale texture analysis as well as non-linear dimensionality reduction techniques to identify salient dimensions of microstructural variation in a 3D post-mortem histological reconstruction of the human amygdala. We observed two axes of subregional variation in this region, describing inferior-superior as well as mediolateral trends in microstructural differentiation that in part recapitulated established atlases of amygdala subnuclei. Translating our approach to in vivo MRI data acquired at 7 Tesla, we could demonstrate the generalizability of these spatial trends across 10 healthy adults. We then cross-referenced microstructural axes with functional blood-oxygen-level dependent (BOLD) signal analysis obtained during task-free conditions, and revealed a close association of structural axes with macroscale functional network embedding, notably the temporo-limbic, default mode, and sensory-motor networks. Our novel multiscale approach consolidates descriptions of amygdala anatomy and function obtained from histological and in vivo imaging techniques.