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Somatodendritic localization of EFA6A, a guanine nucleotide exchange factor for ADP-ribosylation factor 6, and its possible interaction with α-actinin in dendritic spines

Authors

  • Hiroyuki Sakagami,

    1. Division of Histology, Department of Cell Biology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Sendai 980-8575, Japan
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  • Takashi Honma,

    1. Division of Histology, Department of Cell Biology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Sendai 980-8575, Japan
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  • Jun Sukegawa,

    1. Department of Molecular Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Sendai 980-8575, Japan
    2. The Tohoku University 21st Century COE Program Comprehensive Research and Education Center for Planning of Drug and Clinical Evaluation, CRESCENDO, 2-1 Seiryo-machi, Sendai 980-8575, Japan
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  • Yuji Owada,

    1. Division of Histology, Department of Cell Biology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Sendai 980-8575, Japan
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  • Teruyuki Yanagisawa,

    1. Department of Molecular Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Sendai 980-8575, Japan
    2. The Tohoku University 21st Century COE Program Comprehensive Research and Education Center for Planning of Drug and Clinical Evaluation, CRESCENDO, 2-1 Seiryo-machi, Sendai 980-8575, Japan
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  • Hisatake Kondo

    1. Division of Histology, Department of Cell Biology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Sendai 980-8575, Japan
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Dr H. Sakagami, as above.
E-mail: h-sakagami@mail.tains.tohoku.ac.jp

Abstract

EFA6A is a member of the guanine nucleotide exchange factors that can specifically activate ADP ribosylation factor 6 (ARF6). In this study, we identified α-actinin-1 as a possible interacting protein with EFA6A by the yeast two-hybrid screening with its C-terminal region as bait. The central region of α-actinin-1 containing a part of spectrin repeat 1 and spectrin repeats 2–3 is responsible for this interaction. In the hippocampal formation, EFA6A immunoreactivity occurred at a high level as numerous fine puncta in the strata oriens, radiatum, lacunosum-moleculare of the hippocampal CA1–3 subfields and the dentate molecular layer, whereas the immunoreactivity was faint in the neuronal cell layers and the stratum lucidum, the mossy fiber-recipient layer of the CA3 subfield. Double-immunofluorescent analyses revealed a partial overlapping of EFA6A and α-actinin at the dendritic spines of in vivo and cultured hippocampal neurons. Our present findings suggest that EFA6A may form a protein complex with α-actinin and activate ARF6 in close proximity of the actin cytoskeleton and membrane proteins in the dendritic spines.

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