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Fukaya M, Ibuchi K, Sugawara T, Itakura M, Ito A, Shiroshima T, Hara Y, Okamoto H, Luton F, Sakagami H. EFA6A, an Exchange Factor for Arf6, Regulates NGF-Dependent TrkA Recycling From Early Endosomes and Neurite Outgrowth in PC12 Cells. Traffic 2024; 25:e12936. [PMID: 38725127 DOI: 10.1111/tra.12936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 12/18/2023] [Accepted: 12/26/2023] [Indexed: 06/03/2024]
Abstract
Endosomal trafficking of TrkA is a critical process for nerve growth factor (NGF)-dependent neuronal cell survival and differentiation. The small GTPase ADP-ribosylation factor 6 (Arf6) is implicated in NGF-dependent processes in PC12 cells through endosomal trafficking and actin cytoskeleton reorganization. However, the regulatory mechanism for Arf6 in NGF signaling is largely unknown. In this study, we demonstrated that EFA6A, an Arf6-specific guanine nucleotide exchange factor, was abundantly expressed in PC12 cells and that knockdown of EFA6A significantly inhibited NGF-dependent Arf6 activation, TrkA recycling from early endosomes to the cell surface, prolonged ERK1/2 phosphorylation, and neurite outgrowth. We also demonstrated that EFA6A forms a protein complex with TrkA through its N-terminal region, thereby enhancing its catalytic activity for Arf6. Similarly, we demonstrated that EFA6A forms a protein complex with TrkA in cultured dorsal root ganglion (DRG) neurons. Furthermore, cultured DRG neurons from EFA6A knockout mice exhibited disturbed NGF-dependent TrkA trafficking compared with wild-type neurons. These findings provide the first evidence for EFA6A as a key regulator of NGF-dependent TrkA trafficking and signaling.
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Affiliation(s)
- Masahiro Fukaya
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Japan
| | - Kanta Ibuchi
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Japan
| | - Takeyuki Sugawara
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Japan
| | - Makoto Itakura
- Department of Biochemistry, Kitasato University School of Medicine, Sagamihara, Japan
| | - Akiko Ito
- Department of Anesthesiology, Kitasato University School of Medicine, Sagamihara, Japan
| | - Tomoko Shiroshima
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Japan
| | - Yoshinobu Hara
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Japan
| | - Hirotsugu Okamoto
- Department of Anesthesiology, Kitasato University School of Medicine, Sagamihara, Japan
| | - Frédéric Luton
- CNRS, Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), Université Côte d'Azur, Valbonne, France
| | - Hiroyuki Sakagami
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Japan
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Kim H, Jung H, Jung H, Kwon SK, Ko J, Um JW. The small GTPase ARF6 regulates GABAergic synapse development. Mol Brain 2020; 13:2. [PMID: 31907062 PMCID: PMC6945580 DOI: 10.1186/s13041-019-0543-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 12/23/2019] [Indexed: 01/05/2023] Open
Abstract
ADP ribosylation factors (ARFs) are a family of small GTPases composed of six members (ARF1-6) that control various cellular functions, including membrane trafficking and actin cytoskeletal rearrangement, in eukaryotic cells. Among them, ARF1 and ARF6 are the most studied in neurons, particularly at glutamatergic synapses, but their roles at GABAergic synapses have not been investigated. Here, we show that a subset of ARF6 protein is localized at GABAergic synapses in cultured hippocampal neurons. In addition, we found that knockdown (KD) of ARF6, but not ARF1, triggered a reduction in the number of GABAergic synaptic puncta in mature cultured neurons in an ARF activity-dependent manner. ARF6 KD also reduced GABAergic synaptic density in the mouse hippocampal dentate gyrus (DG) region. Furthermore, ARF6 KD in the DG increased seizure susceptibility in an induced epilepsy model. Viewed together, our results suggest that modulating ARF6 and its regulators could be a therapeutic strategy against brain pathologies involving hippocampal network dysfunction, such as epilepsy.
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Affiliation(s)
- Hyeonho Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea
| | - Hyeji Jung
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea
| | - Hyunsu Jung
- Division of Life Sciences, Korea University, Seoul, 02841, South Korea.,Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Seok-Kyu Kwon
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea.
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