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Structural Basis of Astrocytic Ca 2 Signals at Tripartite Synapses

34 Pages Posted: 21 Nov 2018 Sneak Peek Status: Under Review

See all articles by Misa Arizono

Misa Arizono

University of Bordeaux

Aude Panatier

University of Bordeaux

V. V. G. Krishna Inavalli

University of Bordeaux

Thomas Pfeiffer

University of Bordeaux

Julie Angibaud

University of Bordeaux

Jillian Stobart

University of Zurich - Institute of Pharmacology and Toxicology

Luigi Bellocchio

University of Bordeaux

Giovanni Marsicano

University of Bordeaux

Katsuhiko Mikoshiba

RIKEN Center for Brain Science - Laboratory for Developmental Neurobiology

Stéphane H.R. Oliet

University of Bordeaux

Bruno Weber

University of Zurich - Institute of Pharmacology and Toxicology

U. Valentin Nägerl

University of Bordeaux

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Abstract

According to the concept of the ‘tripartite synapse’, synaptic communication is a result of dynamic signaling between pre- and postsynaptic structures as well as perisynaptic astrocytic processes. Recent studies have shown that astrocytic Ca2 signals can be fast and local, supporting the possibility that astrocytes are involved in actively regulating neural circuits at the level of single synapses. However, the anatomical basis of such specific signaling remains unclear, owing to technical difficulties in resolving the spongiform domain of astrocytes where most tripartite synapses are located. Using 3D-STED microscopy in living organotypic brain slices, we could unambiguously resolve the spongiform domain and reveal new aspects of its morphological architecture. We observed a reticular meshwork of nodes and shafts that featured rings of re-connecting astrocytic processes. The majority of dendritic spines were in contact with nodes, correlating in size with them. FRAP experiments and Ca2 imaging showed that individual nodes were biochemically compartmentalized and hosted highly localized spontaneous Ca2 transients. Mapping these Ca2 signals onto STED images of nodes and spines confirmed that they were associated with individual synapses. Our study reveals the nanoscale anatomical organization of astrocytes in living brain slices, identifying nodes as the functional astrocytic component of tripartite synapses, which may provide the anatomical basis for synapse-specific communication between neurons and astrocytes.

Suggested Citation

Arizono, Misa and Panatier, Aude and Inavalli, V. V. G. Krishna and Pfeiffer, Thomas and Angibaud, Julie and Stobart, Jillian and Bellocchio, Luigi and Marsicano, Giovanni and Mikoshiba, Katsuhiko and Oliet, Stéphane H.R. and Weber, Bruno and Nägerl, U. Valentin, Structural Basis of Astrocytic Ca 2 Signals at Tripartite Synapses (November 20, 2018). Available at SSRN: https://ssrn.com/abstract=3287791 or http://dx.doi.org/10.2139/ssrn.3287791
This is a paper under consideration at Cell Press and has not been peer-reviewed.

Misa Arizono

University of Bordeaux

GREThA
Avenue Léon Duguit
Bordeaux, 33608
France

Aude Panatier

University of Bordeaux

GREThA
Avenue Léon Duguit
Bordeaux, 33608
France

V. V. G. Krishna Inavalli

University of Bordeaux

GREThA
Avenue Léon Duguit
Bordeaux, 33608
France

Thomas Pfeiffer

University of Bordeaux

GREThA
Avenue Léon Duguit
Bordeaux, 33608
France

Julie Angibaud

University of Bordeaux

GREThA
Avenue Léon Duguit
Bordeaux, 33608
France

Jillian Stobart

University of Zurich - Institute of Pharmacology and Toxicology

Winterthurerstrasse 190
Zürich, CH-8057
Switzerland

Luigi Bellocchio

University of Bordeaux

GREThA
Avenue Léon Duguit
Bordeaux, 33608
France

Giovanni Marsicano

University of Bordeaux

GREThA
Avenue Léon Duguit
Bordeaux, 33608
France

Katsuhiko Mikoshiba

RIKEN Center for Brain Science - Laboratory for Developmental Neurobiology

2-1 Hirosawa
Wako, Saitama 351-0198
Japan

Stéphane H.R. Oliet

University of Bordeaux

GREThA
Avenue Léon Duguit
Bordeaux, 33608
France

Bruno Weber

University of Zurich - Institute of Pharmacology and Toxicology

Winterthurerstrasse 190
Zürich, CH-8057
Switzerland

U. Valentin Nägerl (Contact Author)

University of Bordeaux ( email )

GREThA
Avenue Léon Duguit
Bordeaux, 33608
France

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