An Optical Neuron-Astrocyte Proximity Assay at Synaptic Distance Scales

J Christopher Octeau; Hua Chai; Ruotian Jiang; Shivan L Bonanno; Kelsey C Martin; Baljit S Khakh

doi:10.1016/j.neuron.2018.03.003

An Optical Neuron-Astrocyte Proximity Assay at Synaptic Distance Scales

Neuron. 2018 Apr 4;98(1):49-66.e9. doi: 10.1016/j.neuron.2018.03.003.

Authors

J Christopher Octeau¹, Hua Chai¹, Ruotian Jiang¹, Shivan L Bonanno², Kelsey C Martin², Baljit S Khakh³

Affiliations

¹ Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095-1751, USA.
² Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095-1751, USA.
³ Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095-1751, USA; Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095-1751, USA. Electronic address: bkhakh@mednet.ucla.edu.

Abstract

Astrocytes are complex bushy cells that serve important functions through close contacts between their processes and synapses. However, the spatial interactions and dynamics of astrocyte processes relative to synapses have proven problematic to study in adult living brain tissue. Here, we report a genetically targeted neuron-astrocyte proximity assay (NAPA) to measure astrocyte-synapse spatial interactions within intact brain preparations and at synaptic distance scales. The method exploits resonance energy transfer between extracellularly displayed fluorescent proteins targeted to synapses and astrocyte processes. We validated the method in the striatal microcircuitry following in vivo expression. We determined the proximity of striatal astrocyte processes to distinct neuronal input pathways, to D1 and D2 medium spiny neuron synapses, and we evaluated how astrocyte-to-excitatory synapse proximity changed following cortical afferent stimulation, during ischemia and in a model of Huntington's disease. NAPA provides a simple approach to measure astrocyte-synapse spatial interactions in a variety of experimental scenarios. VIDEO ABSTRACT.

Keywords: FRET; astrocyte; connectome; striatum; synapses; wiring.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Animals
Astrocytes / chemistry
Astrocytes / physiology*
Astrocytes / ultrastructure
Female
Gene Targeting / methods*
HEK293 Cells
Humans
Male
Mice, Inbred C57BL
Mice, Transgenic
Neurons / chemistry
Neurons / physiology*
Neurons / ultrastructure
Synapses / chemistry
Synapses / physiology*
Synapses / ultrastructure
Synaptic Transmission / physiology*

Abstract

Publication types

MeSH terms

Grants and funding