Holderith N, Heredi J, Kis V, Nusser Z. A High-Resolution Method for Quantitative Molecular Analysis of Functionally Characterized Individual Synapses.
Cell Rep 2021;
32:107968. [PMID:
32726631 PMCID:
PMC7408500 DOI:
10.1016/j.celrep.2020.107968]
[Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/15/2020] [Accepted: 07/08/2020] [Indexed: 12/24/2022] Open
Abstract
Elucidating the molecular mechanisms underlying the functional diversity of synapses requires a high-resolution, sensitive, diffusion-free, quantitative localization method that allows the determination of many proteins in functionally characterized individual synapses. Array tomography permits the quantitative analysis of single synapses but has limited sensitivity, and its application to functionally characterized synapses is challenging. Here, we aim to overcome these limitations by searching the parameter space of different fixation, resin, embedding, etching, retrieval, and elution conditions. Our optimizations reveal that etching epoxy-resin-embedded ultrathin sections with Na-ethanolate and treating them with SDS dramatically increase the labeling efficiency of synaptic proteins. We also demonstrate that this method is ideal for the molecular characterization of individual synapses following paired recordings, two-photon [Ca2+] or glutamate-sensor (iGluSnFR) imaging. This method fills a missing gap in the toolbox of molecular and cellular neuroscience, helping us to reveal how molecular heterogeneity leads to diversity in function.
Etching and antigen retrieval enhance immunoreactions in epoxy-resin-embedded tissue
Biocytin-filled nerve cells can be visualized in epoxy-resin-embedded tissue
Molecular composition of functionally characterized individual synapses is revealed
Multiplexed, postembedding reactions are compatible with STED imaging
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