Journal article
Distinct synaptic localization patterns of brefeldin A-resistant guanine nucleotide exchange factors BRAG2 and BRAG3 in the mouse retina
Journal of Comparative Neurology, Vol.521(4), pp.860-876
2013
Abstract
The BRAG/IQSEC is a family of guanine nucleotide exchange factors for ADP ribosylation factors, small GTPases that regulate membrane trafficking and actin cytoskeleton, and comprises three structurally related members (BRAG1-3) generated from different genes. In the mouse retina, BRAG1 (also known as IQSEC2) was previously shown to localize at synaptic ribbons of photoreceptor terminals and to form a protein complex with RIBEYE. In this study, we examined the immunohistochemical localization of BRAG2 (IQSEC1) and BRAG3 (IQSEC3) in the adult mouse retina at the light and electron microscopic levels. In the outer plexiform layer, BRAG2 showed a punctate distribution in intimate association with dystrophin and β-dystroglycan. Immunoelectron microscopic analysis revealed that BRAG2 localized at specific subcompartments of photoreceptor terminals in both rod spherules and cone pedicles. In the inner plexiform layer, immunolabeling for both BRAG2 and BRAG3 had a punctate appearance, suggestive of synaptic labeling. Double immunostaining demonstrated that BRAG2 colocalized preferentially with PSD-95 and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate-type glutamate receptors (AMPARs). By contrast, BRAG3 colocalized with gephyrin and a subpopulation of inhibitory synapses expressing glycine receptors or γ-aminobutyric acid type A receptors (GABAARs). Immunoelectron microscopic analysis revealed that BRAG2 localized to postsynaptic processes at bipolar dyads, while BRAG3 localized to postsynaptic components at conventional synapses. These findings suggest that BRAG/IQSEC family members have key roles in the function and organization of distinct excitatory and inhibitory synapses in the retina. © 2012 Wiley Periodicals, Inc.
Details
- Title
- Distinct synaptic localization patterns of brefeldin A-resistant guanine nucleotide exchange factors BRAG2 and BRAG3 in the mouse retina
- Authors
- H Sakagami (Author) - Kitasato University School of Medicine, JapanO Katsumata (Author) - Kitasato University School of Medicine, JapanY Hara (Author) - Kitasato University School of Medicine, JapanH Tamaki (Author) - Kitasato University School of Medicine, JapanM Watanabe (Author) - Hokkaido University School of Medicine, JapanRobert J Harvey (Author) - University College London, United KingdomM Fukaya (Author) - Kitasato University School of Medicine, Japan
- Publication details
- Journal of Comparative Neurology, Vol.521(4), pp.860-876
- Publisher
- John Wiley & Sons Inc.
- Date published
- 2013
- DOI
- 10.1002/cne.23206
- ISSN
- 0021-9967
- Organisation Unit
- School of Health; University of the Sunshine Coast, Queensland; School of Health and Sport Sciences - Legacy; Centre for Bioinnovation; School of Health and Behavioural Sciences - Legacy
- Language
- English
- Record Identifier
- 99450470602621
- Output Type
- Journal article
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