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Kontaxi C, Ivanova D, Davenport EC, Kind PC, Cousin MA. Epilepsy-Related CDKL5 Deficiency Slows Synaptic Vesicle Endocytosis in Central Nerve Terminals. J Neurosci 2023; 43:2002-2020. [PMID: 36759195 PMCID: PMC10027047 DOI: 10.1523/jneurosci.1537-22.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 12/20/2022] [Accepted: 01/09/2023] [Indexed: 02/11/2023] Open
Abstract
Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) is a severe early-onset epileptic encephalopathy resulting mainly from de novo mutations in the X-linked CDKL5 gene. To determine whether loss of presynaptic CDKL5 function contributes to CDD, we examined synaptic vesicle (SV) recycling in primary hippocampal neurons generated from Cdkl5 knockout rat males. Using a genetically encoded reporter, we revealed that CDKL5 is selectively required for efficient SV endocytosis. We showed that CDKL5 kinase activity is both necessary and sufficient for optimal SV endocytosis, since kinase-inactive mutations failed to correct endocytosis in Cdkl5 knockout neurons, whereas the isolated CDKL5 kinase domain fully restored SV endocytosis kinetics. Finally, we demonstrated that CDKL5-mediated phosphorylation of amphiphysin 1, a putative presynaptic target, is not required for CDKL5-dependent control of SV endocytosis. Overall, our findings reveal a key presynaptic role for CDKL5 kinase activity and enhance our insight into how its dysfunction may culminate in CDD.SIGNIFICANCE STATEMENT Loss of cyclin-dependent kinase like 5 (CDKL5) function is a leading cause of monogenic childhood epileptic encephalopathy. However, information regarding its biological role is scarce. In this study, we reveal a selective presynaptic role for CDKL5 in synaptic vesicle endocytosis and that its protein kinase activity is both necessary and sufficient for this role. The isolated protein kinase domain is sufficient to correct this loss of function, which may facilitate future gene therapy strategies if presynaptic dysfunction is proven to be central to the disorder. It also reveals that a CDKL5-specific substrate is located at the presynapse, the phosphorylation of which is required for optimal SV endocytosis.
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Affiliation(s)
- Christiana Kontaxi
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
| | - Daniela Ivanova
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
| | - Elizabeth C Davenport
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
| | - Peter C Kind
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
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2
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Gao GB, Sun Y, Fang RD, Wang Y, Wang Y, He QY. Post-translational modifications of CDK5 and their biological roles in cancer. MOLECULAR BIOMEDICINE 2021; 2:22. [PMID: 35006426 PMCID: PMC8607427 DOI: 10.1186/s43556-021-00029-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 02/09/2021] [Indexed: 12/11/2022] Open
Abstract
Post-translational modifications (PTMs) of Cyclin-dependent kinase 5 (CDK5) have emerged as important regulatory mechanisms that modulate cancer development in patients. Though CDK5 is an atypical member of the cyclin-dependent kinase family, its aberrant expression links to cell proliferation, DNA damage response, apoptosis, migration and angiogenesis in cancer. Current studies suggested that, new PTMs on CDK5, including S-nitrosylation, sumoylation, and acetylation, serve as molecular switches to control the kinase activity of CDK5 in the cell. However, a majority of these modifications and their biological significance in cancer remain uncharacterized. In this review, we discussed the role of PTMs on CDK5-mediated signaling cascade, and their possible mechanisms of action in malignant tumors, as well as the challenges and future perspectives in this field. On the basis of the newly identified regulatory signaling pathways of CDK5 related to PTMs, researchers have investigated the cancer therapeutic potential of chemical compounds, small-molecule inhibitors, and competitive peptides by targeting CDK5 and its PTMs. Results of these preclinical studies demonstrated that targeting PTMs of CDK5 yields promising antitumor effects and that clinical translation of these therapeutic strategies is warranted.
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Affiliation(s)
- Gui-Bin Gao
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Yue Sun
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Run-Dong Fang
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Ying Wang
- Institute of Chinese Medical Sciences and State Key Laboratory of Quality Research in Chinese Medicine, University of Macau, Avenida da Universidade, Taipa, Macao SAR, China
| | - Yang Wang
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China.
| | - Qing-Yu He
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China.
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3
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Ferreira APA, Casamento A, Carrillo Roas S, Halff EF, Panambalana J, Subramaniam S, Schützenhofer K, Chan Wah Hak L, McGourty K, Thalassinos K, Kittler JT, Martinvalet D, Boucrot E. Cdk5 and GSK3β inhibit fast endophilin-mediated endocytosis. Nat Commun 2021; 12:2424. [PMID: 33893293 PMCID: PMC8065113 DOI: 10.1038/s41467-021-22603-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 03/18/2021] [Indexed: 12/12/2022] Open
Abstract
Endocytosis mediates the cellular uptake of micronutrients and cell surface proteins. Fast Endophilin-mediated endocytosis, FEME, is not constitutively active but triggered upon receptor activation. High levels of growth factors induce spontaneous FEME, which can be suppressed upon serum starvation. This suggested a role for protein kinases in this growth factor receptor-mediated regulation. Using chemical and genetic inhibition, we find that Cdk5 and GSK3β are negative regulators of FEME. They antagonize the binding of Endophilin to Dynamin-1 and to CRMP4, a Plexin A1 adaptor. This control is required for proper axon elongation, branching and growth cone formation in hippocampal neurons. The kinases also block the recruitment of Dynein onto FEME carriers by Bin1. As GSK3β binds to Endophilin, it imposes a local regulation of FEME. Thus, Cdk5 and GSK3β are key regulators of FEME, licensing cells for rapid uptake by the pathway only when their activity is low.
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Affiliation(s)
- Antonio P A Ferreira
- Institute of Structural and Molecular Biology, University College London, London, UK
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Alessandra Casamento
- Institute of Structural and Molecular Biology, University College London, London, UK
| | - Sara Carrillo Roas
- Institute of Structural and Molecular Biology, University College London, London, UK
| | - Els F Halff
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London, UK
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - James Panambalana
- Institute of Structural and Molecular Biology, University College London, London, UK
| | - Shaan Subramaniam
- Institute of Structural and Molecular Biology, University College London, London, UK
- Institute of Structural and Molecular Biology, Birkbeck College, London, UK
| | - Kira Schützenhofer
- Institute of Structural and Molecular Biology, University College London, London, UK
| | - Laura Chan Wah Hak
- Institute of Structural and Molecular Biology, University College London, London, UK
- Centre for Neural Circuits and Behaviour, University of Oxford, Oxford, UK
| | - Kieran McGourty
- Institute of Structural and Molecular Biology, University College London, London, UK
- Department of Chemical Sciences, Bernal Institute, University of Limerick, Limerick, Ireland
| | | | - Josef T Kittler
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London, UK
| | | | - Emmanuel Boucrot
- Institute of Structural and Molecular Biology, University College London, London, UK.
- Institute of Structural and Molecular Biology, Birkbeck College, London, UK.
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4
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Chen Y, Cao W, Wang L, Zhong T. AMPH1 functions as a tumour suppressor in ovarian cancer via the inactivation of PI3K/AKT pathway. J Cell Mol Med 2020; 24:7652-7659. [PMID: 32476271 PMCID: PMC7339212 DOI: 10.1111/jcmm.15400] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 04/04/2020] [Accepted: 04/27/2020] [Indexed: 12/11/2022] Open
Abstract
AMPH1, an abundant protein in nerve terminals, plays a critical role in the recruitment of dynamin to sites of clathrin-mediated endocytosis. Recently, it is reported to be involved in breast cancer and lung cancer. However, the impact of AMPH1 on ovarian cancer is unclear. In this study, we used gain-of-function and loss-of-function methods to explore the role of AMPH1 in ovarian cancer cells. AMPH1 inhibited ovarian cancer cell growth and cell migration, and promoted caspase-3 activity, resulting in the increase of cell apoptosis. In xenograft mice model, AMPH1 prevented tumour progression. The anti-oncogene effects of AMPH1 on ovarian cancer might be partially due to the inhibition of PI3K/AKT signalling pathway after overexpression of AMPH1. Immunohistochemistry analysis showed that the staining of AMPH1 was remarkably reduced in ovarian cancer tissues compared with normal ovarian tissues. In conclusion, our study identifies AMPH1 as a tumour suppressor in ovarian cancer in vitro and in vivo. This is the first evidence that AMPH1 inhibited cell growth and migration, and induced apoptosis via the inactivation of PI3K/AKT signalling pathway on ovarian cancer, which may be used as an effective strategy.
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Affiliation(s)
- Yajun Chen
- Department of Clinical LaboratoryNanjing Maternity and Child Health Care HospitalWomen’s Hospital of Nanjing Medical UniversityNanjingChina
| | - Wenjiao Cao
- The international Peace Maternity and Child Health HospitalSchool of MedicineThe China Welfare InstituteShanghai Jiao Tong UniversityShanghaiChina
- Shanghai Key Laboratory of Embryo Original DiseasesShanghaiChina
- Shanghai Municipal Key Clinical SpecialtyShanghaiChina
| | - Lihua Wang
- The international Peace Maternity and Child Health HospitalSchool of MedicineThe China Welfare InstituteShanghai Jiao Tong UniversityShanghaiChina
- Shanghai Key Laboratory of Embryo Original DiseasesShanghaiChina
- Shanghai Municipal Key Clinical SpecialtyShanghaiChina
| | - Tianying Zhong
- Department of Clinical LaboratoryNanjing Maternity and Child Health Care HospitalWomen’s Hospital of Nanjing Medical UniversityNanjingChina
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5
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Casamento A, Boucrot E. Molecular mechanism of Fast Endophilin-Mediated Endocytosis. Biochem J 2020; 477:2327-2345. [PMID: 32589750 PMCID: PMC7319585 DOI: 10.1042/bcj20190342] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 05/11/2020] [Accepted: 05/18/2020] [Indexed: 12/13/2022]
Abstract
Endocytosis mediates the cellular uptake of micronutrients and cell surface proteins. Clathrin-mediated endocytosis (CME) is the housekeeping pathway in resting cells but additional Clathrin-independent endocytic (CIE) routes, including Fast Endophilin-Mediated Endocytosis (FEME), internalize specific cargoes and support diverse cellular functions. FEME is part of the Dynamin-dependent subgroup of CIE pathways. Here, we review our current understanding of the molecular mechanism of FEME. Key steps are: (i) priming, (ii) cargo selection, (iii) membrane curvature and carrier formation, (iv) membrane scission and (v) cytosolic transport. All steps are controlled by regulatory mechanisms mediated by phosphoinositides and by kinases such as Src, LRRK2, Cdk5 and GSK3β. A key feature of FEME is that it is not constitutively active but triggered upon the stimulation of selected cell surface receptors by their ligands. In resting cells, there is a priming cycle that concentrates Endophilin into clusters on discrete locations of the plasma membrane. In the absence of receptor activation, the patches quickly abort and new cycles are initiated nearby, constantly priming the plasma membrane for FEME. Upon activation, receptors are swiftly sorted into pre-existing Endophilin clusters, which then bud to form FEME carriers within 10 s. We summarize the hallmarks of FEME and the techniques and assays required to identify it. Next, we review similarities and differences with other CIE pathways and proposed cargoes that may use FEME to enter cells. Finally, we submit pending questions and future milestones and discuss the exciting perspectives that targeting FEME may boost treatments against cancer and neurodegenerative diseases.
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Affiliation(s)
- Alessandra Casamento
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, U.K
| | - Emmanuel Boucrot
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, U.K
- Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, U.K
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6
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Abe T, La TM, Miyagaki Y, Oya E, Wei FY, Sumida K, Fujise K, Takeda T, Tomizawa K, Takei K, Yamada H. Phosphorylation of cortactin by cyclin-dependent kinase 5 modulates actin bundling by the dynamin 1-cortactin ring-like complex and formation of filopodia and lamellipodia in NG108-15 glioma-derived cells. Int J Oncol 2018; 54:550-558. [PMID: 30570111 PMCID: PMC6317663 DOI: 10.3892/ijo.2018.4663] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 11/09/2018] [Indexed: 12/14/2022] Open
Abstract
Dynamin copolymerizes with cortactin to form a ring-like complex that bundles and stabilizes actin filaments. Actin bundle formation is crucial for generation of filopodia and lamellipodia, which guide migration, invasion, and metastasis of cancer cells. However, it is unknown how the dynamin-cortactin complex regulates actin bundle formation. The present study investigated phosphorylation of cortactin by cyclin-dependent kinase 5 (CDK5) and its effect on actin bundle formation by the dynamin-cortactin complex. CDK5 directly phosphorylated cortactin at T145/T219 in vitro. Phosphomimetic mutants in which one or both of these threonine residues was substituted by aspartate were used. The three phosphomimetic mutants (T145D, T219D and T145DT219D) had a decreased affinity for F-actin. Furthermore, electron microscopy demonstrated that these phosphomimetic mutants could not form a ring-like complex with dynamin 1. Consistently, the dynamin 1-phosphomimetic cortactin complexes exhibited decreased actin-bundling activity. Expression of the phosphomimetic mutants resulted in not only aberrant lamellipodia and short filopodia but also cell migration in NG108-15 glioma-derived cells. These results indicate that phosphorylation of cortactin by CDK5 regulates formation of lamellipodia and filopodia by modulating dynamin 1/cortactin-dependent actin bundling. Taken together, these findings suggest that CDK5 is a potential molecular target for anticancer therapy.
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Affiliation(s)
- Tadashi Abe
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - The Mon La
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Yuuzi Miyagaki
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Eri Oya
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Fan-Yan Wei
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Kento Sumida
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Kenshiro Fujise
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Tetsuya Takeda
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Kazuhito Tomizawa
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Kohji Takei
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Hiroshi Yamada
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
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7
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Dixit AB, Banerjee J, Tripathi M, Sarkar C, Chandra PS. Synaptic roles of cyclin-dependent kinase 5 & its implications in epilepsy. Indian J Med Res 2018. [PMID: 28639593 PMCID: PMC5501049 DOI: 10.4103/ijmr.ijmr_1249_14] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
There is an urgent need to understand the molecular mechanisms underlying epilepsy to find novel prognostic/diagnostic biomarkers to prevent epilepsy patients at risk. Cyclin-dependent kinase 5 (CDK5) is involved in multiple neuronal functions and plays a crucial role in maintaining homeostatic synaptic plasticity by regulating intracellular signalling cascades at synapses. CDK5 deregulation is shown to be associated with various neurodegenerative diseases such as Alzheimer's disease. The association between chronic loss of CDK5 and seizures has been reported in animal models of epilepsy. Genetic expression of CDK5 at transcriptome level has been shown to be abnormal in intractable epilepsy. In this review various possible mechanisms by which deregulated CDK5 may alter synaptic transmission and possibly lead to epileptogenesis have been discussed. Further, CDK5 has been proposed as a potential biomarker as well as a pharmacological target for developing treatments for epilepsy.
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Affiliation(s)
- Aparna Banerjee Dixit
- Center for Excellence in Epilepsy, A Joint National Brain Research Centre (NBRC)- All India Institute of Medical Sciences (AIIMS) Collaboration, NBRC, Gurugram, India
| | - Jyotirmoy Banerjee
- Center for Excellence in Epilepsy, A Joint National Brain Research Centre (NBRC)- All India Institute of Medical Sciences (AIIMS) Collaboration, NBRC, Gurugram, India
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8
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Vargas KJ, Schrod N, Davis T, Fernandez-Busnadiego R, Taguchi YV, Laugks U, Lucic V, Chandra SS. Synucleins Have Multiple Effects on Presynaptic Architecture. Cell Rep 2017; 18:161-173. [PMID: 28052246 DOI: 10.1016/j.celrep.2016.12.023] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/21/2016] [Accepted: 12/07/2016] [Indexed: 02/01/2023] Open
Abstract
Synucleins (α, β, γ-synuclein) are a family of abundant presynaptic proteins. α-Synuclein is causally linked to the pathogenesis of Parkinson's disease (PD). In an effort to define their physiological and pathological function or functions, we investigated the effects of deleting synucleins and overexpressing α-synuclein PD mutations, in mice, on synapse architecture using electron microscopy (EM) and cryoelectron tomography (cryo-ET). We show that synucleins are regulators of presynapse size and synaptic vesicle (SV) pool organization. Using cryo-ET, we observed that deletion of synucleins increases SV tethering to the active zone but decreases the inter-linking of SVs by short connectors. These ultrastructural changes were correlated with discrete protein phosphorylation changes in αβγ-synuclein-/- neurons. We also determined that α-synuclein PD mutants (PARK1/hA30P and PARK4/hα-syn) primarily affected presynaptic cytomatrix proximal to the active zone, congruent with previous findings that these PD mutations decrease neurotransmission. Collectively, our results suggest that synucleins are important orchestrators of presynaptic terminal topography.
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Affiliation(s)
- Karina J Vargas
- Department of Neurology, Yale University, New Haven, CT 06536, USA; Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University, New Haven, CT 06536, USA
| | - Nikolas Schrod
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Taylor Davis
- Department of Neurology, Yale University, New Haven, CT 06536, USA; Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University, New Haven, CT 06536, USA
| | - Ruben Fernandez-Busnadiego
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University, New Haven, CT 06536, USA; Department of Cell Biology, School of Medicine, Yale University, New Haven, CT 06510, USA; Howard Hughes Medical Institute, School of Medicine, Yale University, New Haven, CT 06510, USA
| | - Yumiko V Taguchi
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University, New Haven, CT 06536, USA; Department of Cell Biology, School of Medicine, Yale University, New Haven, CT 06510, USA
| | - Ulrike Laugks
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Vladan Lucic
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
| | - Sreeganga S Chandra
- Department of Neurology, Yale University, New Haven, CT 06536, USA; Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University, New Haven, CT 06536, USA; Department of Neuroscience, Yale University, New Haven, CT 06519, USA.
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9
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Saito M, Otsu W, Hsu KS, Chuang JZ, Yanagisawa T, Shieh V, Kaitsuka T, Wei FY, Tomizawa K, Sung CH. Tctex-1 controls ciliary resorption by regulating branched actin polymerization and endocytosis. EMBO Rep 2017; 18:1460-1472. [PMID: 28607034 DOI: 10.15252/embr.201744204] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/13/2017] [Accepted: 05/16/2017] [Indexed: 11/09/2022] Open
Abstract
The primary cilium is a plasma membrane-protruding sensory organelle that undergoes regulated assembly and resorption. While the assembly process has been studied extensively, the cellular machinery that governs ciliary resorption is less well understood. Previous studies showed that the ciliary pocket membrane is an actin-rich, endocytosis-active periciliary subdomain. Furthermore, Tctex-1, originally identified as a cytoplasmic dynein light chain, has a dynein-independent role in ciliary resorption upon phosphorylation at Thr94. Here, we show that the remodeling and endocytosis of the ciliary pocket membrane are accelerated during ciliary resorption. This process depends on phospho(T94)Tctex-1, actin, and dynamin. Mechanistically, Tctex-1 physically and functionally interacts with the actin dynamics regulators annexin A2, Arp2/3 complex, and Cdc42. Phospho(T94)Tctex-1 is required for Cdc42 activation before the onset of ciliary resorption. Moreover, inhibiting clathrin-dependent endocytosis or suppressing Rab5GTPase on early endosomes effectively abrogates ciliary resorption. Taken together with the epistasis functional assays, our results support a model in which phospho(T94)Tctex-1-regulated actin polymerization and periciliary endocytosis play an active role in orchestrating the initial phase of ciliary resorption.
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Affiliation(s)
- Masaki Saito
- Department of Molecular Pharmacology, Graduate School of Medicine, Tohoku University, Aoba-ku Sendai, Japan .,Department of Cellular Signaling, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-ku Sendai, Japan.,Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY, USA
| | - Wataru Otsu
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY, USA
| | - Kuo-Shun Hsu
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY, USA
| | - Jen-Zen Chuang
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY, USA
| | - Teruyuki Yanagisawa
- Department of Molecular Pharmacology, Graduate School of Medicine, Tohoku University, Aoba-ku Sendai, Japan
| | - Vincent Shieh
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY, USA
| | - Taku Kaitsuka
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Fan-Yan Wei
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Kazuhito Tomizawa
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Ching-Hwa Sung
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY, USA .,Department of Cell and Developmental Biology, Weill Medical College of Cornell University, New York, NY, USA
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10
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Yamada H, Kikuchi T, Masumoto T, Wei FY, Abe T, Takeda T, Nishiki T, Tomizawa K, Watanabe M, Matsui H, Takei K. Possible role of cortactin phosphorylation by protein kinase Cα in actin-bundle formation at growth cone. Biol Cell 2015; 107:319-30. [PMID: 26033110 DOI: 10.1111/boc.201500032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 05/28/2015] [Indexed: 11/29/2022]
Abstract
BACKGROUND INFORMATION Cortactin contributes to growth cone morphogenesis by forming with dynamin, ring-shaped complexes that mechanically bundle and stabilise F-actin. However, the regulatory mechanism of cortactin action is poorly understood. RESULTS Immunofluorescence microscopy revealed that protein kinase C (PKC) α colocalises with cortactin at growth cone filopodia in SH-SY5Y neuroblastoma cells. PKC activation by phorbol 12-myristate 13-acetate causes cortactin phosphorylation, filopodial retraction and F-actin-bundle loss. Moreover, PKCα directly phosphorylates cortactin in vitro at S135/T145/S172, mitigating both cortactin's actin-binding and actin-crosslinking activity, whereas cellular expression of a phosphorylation-mimetic cortactin mutant hinders filopodial formation with a significant decrease of actin bundles. CONCLUSIONS Our results indicate that PKC-mediated cortactin phosphorylation might be implicated in the maintenance of growth cone.
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Affiliation(s)
- Hiroshi Yamada
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan.,CREST, Japan Science and Technology Agency, Kita-ku, Okayama, 700-8558, Japan
| | - Tatsuya Kikuchi
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan
| | - Toshio Masumoto
- Department of Cell Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan
| | - Fan-Yan Wei
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, 860-8556, Japan
| | - Tadashi Abe
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan.,CREST, Japan Science and Technology Agency, Kita-ku, Okayama, 700-8558, Japan
| | - Tetsuya Takeda
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan.,CREST, Japan Science and Technology Agency, Kita-ku, Okayama, 700-8558, Japan
| | - Teiichi Nishiki
- Department of Cell Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan
| | - Kazuhito Tomizawa
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, 860-8556, Japan
| | - Masami Watanabe
- Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan
| | - Hideki Matsui
- Department of Cell Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan
| | - Kohji Takei
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan.,CREST, Japan Science and Technology Agency, Kita-ku, Okayama, 700-8558, Japan
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11
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Phosphorylation of synapsin I by cyclin-dependent kinase-5 sets the ratio between the resting and recycling pools of synaptic vesicles at hippocampal synapses. J Neurosci 2014; 34:7266-80. [PMID: 24849359 DOI: 10.1523/jneurosci.3973-13.2014] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cyclin-dependent kinase-5 (Cdk5) was reported to downscale neurotransmission by sequestering synaptic vesicles (SVs) in the release-reluctant resting pool, but the molecular targets mediating this activity remain unknown. Synapsin I (SynI), a major SV phosphoprotein involved in the regulation of SV trafficking and neurotransmitter release, is one of the presynaptic substrates of Cdk5, which phosphorylates it in its C-terminal region at Ser(549) (site 6) and Ser(551) (site 7). Here we demonstrate that Cdk5 phosphorylation of SynI fine tunes the recruitment of SVs to the active recycling pool and contributes to the Cdk5-mediated homeostatic responses. Phosphorylation of SynI by Cdk5 is physiologically regulated and enhances its binding to F-actin. The effects of Cdk5 inhibition on the size and depletion kinetics of the recycling pool, as well as on SV distribution within the nerve terminal, are virtually abolished in mouse SynI knock-out (KO) neurons or in KO neurons expressing the dephosphomimetic SynI mutants at sites 6,7 or site 7 only. The observation that the single site-7 mutant phenocopies the effects of the deletion of SynI identifies this site as the central switch in mediating the synaptic effects of Cdk5 and demonstrates that SynI is necessary and sufficient for achieving the effects of the kinase on SV trafficking. The phosphorylation state of SynI by Cdk5 at site 7 is regulated during chronic modification of neuronal activity and is an essential downstream effector for the Cdk5-mediated homeostatic scaling.
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12
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Sekiguchi M, Katayama S, Hatano N, Shigeri Y, Sueyoshi N, Kameshita I. Identification of amphiphysin 1 as an endogenous substrate for CDKL5, a protein kinase associated with X-linked neurodevelopmental disorder. Arch Biochem Biophys 2013; 535:257-67. [DOI: 10.1016/j.abb.2013.04.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 04/18/2013] [Accepted: 04/20/2013] [Indexed: 10/26/2022]
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13
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Abstract
Cyclin-dependent kinase 5 (Cdk5) is a multifaceted serine/threonine kinase protein with important roles in the nervous system. Two related proteins, p35 and p39, activate Cdk5 upon direct binding. Over the past decade, Cdk5 activity has been demonstrated to regulate many events during brain development, including neuronal migration as well as axon and dendrite development. Recent evidence also suggests a pivotal role for Cdk5 in synaptic plasticity, behavior, and cognition. Dysfunction of Cdk5 has been implicated in a number of neurological disorders and neurodegenerative diseases including Alzheimer's disease, amyotrophic lateral sclerosis, Niemann-Pick type C disease, and ischemia. Hyperactivation of Cdk5 due to the conversion of p35 to p25 by the calcium-dependent protease calpain during neurotoxicity also contributes to the pathological state. This review surveys recent literature surrounding Cdk5 in synaptic plasticity and homeostasis, with particular emphasis on Cdk5 kinase activity under neurodegenerative conditions.
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Affiliation(s)
- Susan C Su
- Howard Hughes Medical Institute, Cambridge, Massachusetts 02139, USA
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14
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Rohrbeck A, Borlak J. Cancer genomics identifies regulatory gene networks associated with the transition from dysplasia to advanced lung adenocarcinomas induced by c-Raf-1. PLoS One 2009; 4:e7315. [PMID: 19812696 PMCID: PMC2754338 DOI: 10.1371/journal.pone.0007315] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Accepted: 09/13/2009] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Lung cancer is a leading cause of cancer morbidity. To improve an understanding of molecular causes of disease a transgenic mouse model was investigated where targeted expression of the serine threonine kinase c-Raf to respiratory epithelium induced initially dysplasia and subsequently adenocarcinomas. This enables dissection of genetic events associated with precancerous and cancerous lesions. METHODOLOGY/PRINCIPAL FINDINGS By laser microdissection cancer cell populations were harvested and subjected to whole genome expression analyses. Overall 473 and 541 genes were significantly regulated, when cancer versus transgenic and non-transgenic cells were compared, giving rise to three distinct and one common regulatory gene network. At advanced stages of tumor growth predominately repression of gene expression was observed, but genes previously shown to be up-regulated in dysplasia were also up-regulated in solid tumors. Regulation of developmental programs as well as epithelial mesenchymal and mesenchymal endothelial transition was a hall mark of adenocarcinomas. Additionally, genes coding for cell adhesion, i.e. the integrins and the tight and gap junction proteins were repressed, whereas ligands for receptor tyrosine kinase such as epi- and amphiregulin were up-regulated. Notably, Vegfr- 2 and its ligand Vegfd, as well as Notch and Wnt signalling cascades were regulated as were glycosylases that influence cellular recognition. Other regulated signalling molecules included guanine exchange factors that play a role in an activation of the MAP kinases while several tumor suppressors i.e. Mcc, Hey1, Fat3, Armcx1 and Reck were significantly repressed. Finally, probable molecular switches forcing dysplastic cells into malignantly transformed cells could be identified. CONCLUSIONS/SIGNIFICANCE This study provides insight into molecular pertubations allowing dysplasia to progress further to adenocarcinoma induced by exaggerted c-Raf kinase activity.
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Affiliation(s)
- Astrid Rohrbeck
- Department of Molecular Medicine and Medical Biotechnology, Fraunhofer Institute of Toxicology and Experimental Medicine, Hannover, Germany
| | - Jürgen Borlak
- Department of Molecular Medicine and Medical Biotechnology, Fraunhofer Institute of Toxicology and Experimental Medicine, Hannover, Germany
- Center for Pharmacology and Toxicology, Hannover Medical School, Hannover, Germany
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15
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Hawasli AH, Koovakkattu D, Hayashi K, Anderson AE, Powell CM, Sinton CM, Bibb JA, Cooper DC. Regulation of hippocampal and behavioral excitability by cyclin-dependent kinase 5. PLoS One 2009; 4:e5808. [PMID: 19529798 PMCID: PMC2695674 DOI: 10.1371/journal.pone.0005808] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Accepted: 05/07/2009] [Indexed: 01/19/2023] Open
Abstract
Cyclin-dependent kinase 5 (Cdk5) is a proline-directed serine/threonine kinase that has been implicated in learning, synaptic plasticity, neurotransmission, and numerous neurological disorders. We previously showed that conditional loss of Cdk5 in adult mice enhanced hippocampal learning and plasticity via modulation of calpain-mediated N-methyl-D-aspartic acid receptor (NMDAR) degradation. In the present study, we characterize the enhanced synaptic plasticity and examine the effects of long-term Cdk5 loss on hippocampal excitability in adult mice. Field excitatory post-synaptic potentials (fEPSPs) from the Schaffer collateral CA1 subregion of the hippocampus (SC/CA1) reveal that loss of Cdk5 altered theta burst topography and enhanced post-tetanic potentiation. Since Cdk5 governs NMDAR NR2B subunit levels, we investigated the effects of long-term Cdk5 knockout on hippocampal neuronal excitability by measuring NMDAR-mediated fEPSP magnitudes and population-spike thresholds. Long-term loss of Cdk5 led to increased Mg2+-sensitive potentials and a lower threshold for epileptiform activity and seizures. Biochemical analyses were performed to better understand the role of Cdk5 in seizures. Induced-seizures in wild-type animals led to elevated amounts of p25, the Cdk5-activating cofactor. Long-term, but not acute, loss of Cdk5 led to decreased p25 levels, suggesting that Cdk5/p25 may be activated as a homeostatic mechanism to attenuate epileptiform activity. These findings indicate that Cdk5 regulates synaptic plasticity, controls neuronal and behavioral stimulus-induced excitability and may be a novel pharmacological target for cognitive and anticonvulsant therapies.
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Affiliation(s)
- Ammar H. Hawasli
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Della Koovakkattu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Kanehiro Hayashi
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Anne E. Anderson
- Departments of Pediatrics, Neurology and Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Craig M. Powell
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Christopher M. Sinton
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - James A. Bibb
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail:
| | - Donald C. Cooper
- Department of Psychology and Neuroscience, Institute for Behavioral Genetics, University of Colorado, Boulder, Colorado, United States of America
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16
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Liberali P, Rämö P, Pelkmans L. Protein kinases: starting a molecular systems view of endocytosis. Annu Rev Cell Dev Biol 2008; 24:501-23. [PMID: 18598215 DOI: 10.1146/annurev.cellbio.041008.145637] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The field of endocytosis is in strong need of formal biophysical modeling and mathematical analysis. At the same time, endocytosis must be much better integrated into cellular physiology to understand the former's complex behavior in such a wide range of phenotypic variations. Furthermore, the concept that endocytosis provides the space-time for signal transduction can now be experimentally addressed. In this review, we discuss these principles and argue for a systematic and top-down approach to study the endocytic membrane system. We provide a summary of published observations on protein kinases regulating endocytic machinery components and discuss global unbiased approaches to further map out kinase regulatory networks. In particular, protein phosphorylation is at the heart of controlling the physical properties of endocytosis and of integrating these physical properties into the signal transduction networks of the cell to allow a fine-tuned response to the continuously varying physiological conditions of a cell.
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Affiliation(s)
- Prisca Liberali
- Institute of Molecular Systems Biology, ETH Zurich, CH-8093 Zurich, Switzerland
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17
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Choudhury M, Kleiner O, Chung R, Barden L, Morgan L, Patel TR, Staddon JM. Amphiphysin I phosphorylation on residue threonine 260 in a pentylenetetrazole-induced seizure model. Neurosci Lett 2008; 444:245-9. [DOI: 10.1016/j.neulet.2008.08.055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 07/17/2008] [Accepted: 08/11/2008] [Indexed: 10/21/2022]
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18
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Craft GE, Graham ME, Bache N, Larsen MR, Robinson PJ. The in vivo phosphorylation sites in multiple isoforms of amphiphysin I from rat brain nerve terminals. Mol Cell Proteomics 2008; 7:1146-61. [PMID: 18344231 DOI: 10.1074/mcp.m700351-mcp200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Amphiphysin I (amphI) is dephosphorylated by calcineurin during nerve terminal depolarization and synaptic vesicle endocytosis (SVE). Some amphI phosphorylation sites (phosphosites) have been identified with in vitro studies or phosphoproteomics screens. We used a multifaceted strategy including 32P tracking to identify all in vivo amphI phosphosites and determine their relative abundance and potential relevance to SVE. AmphI was extracted from 32P-labeled synaptosomes, phosphopeptides were isolated from proteolytic digests using TiO2 chromatography, and mass spectrometry revealed 13 sites: serines 250, 252, 262, 268, 272, 276, 285, 293, 496, 514, 539, and 626 and Thr-310. These were distributed into two clusters around the proline-rich domain and the C-terminal Src homology 3 domain. Hierarchical phosphorylation of Ser-262 preceded phosphorylation of Ser-268, -272, -276, and -285. Off-line HPLC separation and two-dimensional tryptic mapping of 32P-labeled amphI revealed that Thr-310, Ser-293, Ser-285, Ser-272, Ser-276, and Ser-268 contained the highest 32P incorporation and were the most stimulus-sensitive. Individually Thr-310 and Ser-293 were the most abundant phosphosites, incorporating 16 and 23% of the 32P. The multiple phosphopeptides containing Ser-268, Ser-276, Ser-272, and Ser-285 had 27% of the 32P. Evidence for a role for at least one proline-directed protein kinase and one non-proline-directed kinase was obtained. Four phosphosites predicted for non-proline-directed kinases, Ser-626, -250, -252, and -539, contained low amounts of 32P and were not depolarization-responsive. At least one alternatively spliced amphI isoform was identified in synaptosomes as being constitutively phosphorylated because it did not incorporate 32P during the 1-h labeling period. Multiple phosphosites from amphI-co-migrating synaptosomal proteins were also identified, including SGIP (Src homology 3 domain growth factor receptor-bound 2 (Grb2)-like (endophilin)-interacting protein 1), AAK1, eps15R, MAP6, alpha/beta-adducin, and HCN1. The results reveal two sets of amphI phosphosites that are either dynamically turning over or constitutively phosphorylated in nerve terminals and improve understanding of the role of individual amphI sites or phosphosite clusters in synaptic SVE.
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Affiliation(s)
- George E Craft
- Cell Signalling Unit, Children's Medical Research Institute, The University of Sydney, Locked Bag 23, Wentworthville, New South Wales 2145, Australia
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Wu Y, Liang S, Oda Y, Ohmori I, Nishiki TI, Takei K, Matsui H, Tomizawa K. Truncations of amphiphysin I by calpain inhibit vesicle endocytosis during neural hyperexcitation. EMBO J 2007; 26:2981-90. [PMID: 17541403 PMCID: PMC1894779 DOI: 10.1038/sj.emboj.7601741] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2007] [Accepted: 05/08/2007] [Indexed: 11/09/2022] Open
Abstract
Under normal physiological conditions, synaptic vesicle endocytosis is regulated by phosphorylation and Ca(2+)-dependent dephosphorylation of endocytic proteins such as amphiphysin and dynamin. To investigate the regulatory mechanisms that may occur under the conditions of excessive presynaptic Ca(2+) influx observed preceding neural hyperexcitation, we examined hippocampal slices following high-potassium or high-frequency electrical stimulation (HFS). In both cases, three truncated forms of amphiphysin I resulted from cleavage by the protease calpain. In vitro, the binding of truncated amphiphysin I to dynamin I and copolymerization into rings with dynamin I were inhibited, but its interaction with liposomes was not affected. Moreover, overexpression of the truncated form of amphiphysin I inhibited endocytosis of transferrin and synaptic vesicles. Inhibiting calpain prevented HFS-induced depression of presynaptic transmission. Finally, calpain-dependent amphiphysin I cleavage attenuated kainate-induced seizures. These results suggest that calpain-dependent cleavage of amphiphysin I inhibits synaptic vesicle endocytosis during neural hyperexcitation and demonstrate a novel post-translational regulation of endocytosis.
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Affiliation(s)
- Yumei Wu
- Department of Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Shuang Liang
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Yoshiya Oda
- Laboratory of Seed Finding Technology, Eisai Co., Ltd, Tsukuba, Japan
| | - Iori Ohmori
- Department of Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Tei-ichi Nishiki
- Department of Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Kohji Takei
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Hideki Matsui
- Department of Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Kazuhito Tomizawa
- Department of Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
- Department of Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Shikata-cho 2-5-1, Okayama 700-8558, Japan. Tel.: +81 86 235 7107; Fax: +81 86 235 7111; E-mail:
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