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Ramirez-Franco J, Debreux K, Sangiardi M, Belghazi M, Kim Y, Lee SH, Lévêque C, Seagar M, El Far O. The downregulation of Kv 1 channels in Lgi1 -/-mice is accompanied by a profound modification of its interactome and a parallel decrease in Kv 2 channels. Neurobiol Dis 2024; 196:106513. [PMID: 38663634 DOI: 10.1016/j.nbd.2024.106513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 03/12/2024] [Accepted: 04/23/2024] [Indexed: 05/03/2024] Open
Abstract
In animal models of LGI1-dependent autosomal dominant lateral temporal lobe epilepsy, Kv1 channels are downregulated, suggesting their crucial involvement in epileptogenesis. The molecular basis of Kv1 channel-downregulation in LGI1 knock-out mice has not been elucidated and how the absence of this extracellular protein induces an important modification in the expression of Kv1 remains unknown. In this study we analyse by immunofluorescence the modifications in neuronal Kv1.1 and Kv1.2 distribution throughout the hippocampal formation of LGI1 knock-out mice. We show that Kv1 downregulation is not restricted to the axonal compartment, but also takes place in the somatodendritic region and is accompanied by a drastic decrease in Kv2 expression levels. Moreover, we find that the downregulation of these Kv channels is associated with a marked increase in bursting patterns. Finally, mass spectrometry uncovered key modifications in the Kv1 interactome that highlight the epileptogenic implication of Kv1 downregulation in LGI1 knock-out animals.
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Affiliation(s)
- Jorge Ramirez-Franco
- INSERM UMR_S 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, Aix-Marseille Université, 13015 Marseille, France.
| | - Kévin Debreux
- INSERM UMR_S 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, Aix-Marseille Université, 13015 Marseille, France
| | - Marion Sangiardi
- INSERM UMR_S 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, Aix-Marseille Université, 13015 Marseille, France
| | - Maya Belghazi
- Marseille Protéomique (MaP), Plateforme Protéomique IMM, CNRS FR3479, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13009 Marseille, France
| | - Yujin Kim
- Department of Physiology, Cell Physiology Lab, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul 03080, South Korea
| | - Suk-Ho Lee
- Department of Physiology, Cell Physiology Lab, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul 03080, South Korea
| | - Christian Lévêque
- INSERM UMR_S 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, Aix-Marseille Université, 13015 Marseille, France
| | - Michael Seagar
- INSERM UMR_S 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, Aix-Marseille Université, 13015 Marseille, France
| | - Oussama El Far
- INSERM UMR_S 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, Aix-Marseille Université, 13015 Marseille, France.
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Arriagada-Diaz J, Flores-Muñoz C, Gómez-Soto B, Labraña-Allende M, Mattar-Araos M, Prado-Vega L, Hinostroza F, Gajardo I, Guerra-Fernández MJ, Bevilacqua JA, Cárdenas AM, Bitoun M, Ardiles AO, Gonzalez-Jamett AM. A centronuclear myopathy-causing mutation in dynamin-2 disrupts neuronal morphology and excitatory synaptic transmission in a murine model of the disease. Neuropathol Appl Neurobiol 2023; 49:e12918. [PMID: 37317811 DOI: 10.1111/nan.12918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 04/30/2023] [Accepted: 06/02/2023] [Indexed: 06/16/2023]
Abstract
AIMS Dynamin-2 is a large GTPase, a member of the dynamin superfamily that regulates membrane remodelling and cytoskeleton dynamics. Mutations in the dynamin-2 gene (DNM2) cause autosomal dominant centronuclear myopathy (CNM), a congenital neuromuscular disorder characterised by progressive weakness and atrophy of the skeletal muscles. Cognitive defects have been reported in some DNM2-linked CNM patients suggesting that these mutations can also affect the central nervous system (CNS). Here we studied how a dynamin-2 CNM-causing mutation influences the CNS function. METHODS Heterozygous mice harbouring the p.R465W mutation in the dynamin-2 gene (HTZ), the most common causing autosomal dominant CNM, were used as disease model. We evaluated dendritic arborisation and spine density in hippocampal cultured neurons, analysed excitatory synaptic transmission by electrophysiological field recordings in hippocampal slices, and evaluated cognitive function by performing behavioural tests. RESULTS HTZ hippocampal neurons exhibited reduced dendritic arborisation and lower spine density than WT neurons, which was reversed by transfecting an interference RNA against the dynamin-2 mutant allele. Additionally, HTZ mice showed defective hippocampal excitatory synaptic transmission and reduced recognition memory compared to the WT condition. CONCLUSION Our findings suggest that the dynamin-2 p.R465W mutation perturbs the synaptic and cognitive function in a CNM mouse model and support the idea that this GTPase plays a key role in regulating neuronal morphology and excitatory synaptic transmission in the hippocampus.
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Affiliation(s)
- Jorge Arriagada-Diaz
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Programa de Magister en Ciencias, Mención Neurociencia, Universidad de Valparaíso, Valparaíso, Chile
| | - Carolina Flores-Muñoz
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Bárbara Gómez-Soto
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Programa de Magister en Ciencias Médicas, Mención Biología Celular y Molecular, Universidad de Valparaíso, Valparaíso, Chile
| | - Marjorie Labraña-Allende
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Programa de Magister en Ciencias Médicas, Mención Biología Celular y Molecular, Universidad de Valparaíso, Valparaíso, Chile
| | - Michelle Mattar-Araos
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Lorena Prado-Vega
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Programa de Magister en Ciencias, Mención Neurociencia, Universidad de Valparaíso, Valparaíso, Chile
| | - Fernando Hinostroza
- Centro de Investigación de Estudios Avanzados del Maule, CIEAM, Vicerrectoría de Investigación y Postgrado, Universidad Católica del Maule, Talca, Chile
- Centro de Investigación en Neuropsicología y Neurociencias Cognitivas, Facultad de Ciencias de la Salud, Universidad Católica del Maule, Talca, Chile
- Escuela de Química y Farmacia, Departamento de Medicina Traslacional, Facultad de Medicina, Universidad Católica del Maule, Talca, Chile
| | - Ivana Gajardo
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - Jorge A Bevilacqua
- Departamento de Neurología y Neurocirugía, Hospital Clínico Universidad de Chile, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Ana M Cárdenas
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Marc Bitoun
- Sorbonne Université, Inserm, Institut de Myologie, Centre de Recherche en Myologie, Paris, F-75013, France
| | - Alvaro O Ardiles
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Centro de Neurología Traslacional, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile
- Centro Interdisciplinario de Estudios en Salud, Facultad de Medicina, Universidad de Valparaíso, Viña del Mar, Chile
| | - Arlek M Gonzalez-Jamett
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Escuela de Química y Farmacia, Facultad de Farmacia, Universidad de Valparaíso, Valparaíso, Chile
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Khurana H, Pucadyil TJ. "Gearing" up for dynamin-catalyzed membrane fission. Curr Opin Cell Biol 2023; 83:102204. [PMID: 37451176 DOI: 10.1016/j.ceb.2023.102204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 06/13/2023] [Accepted: 06/16/2023] [Indexed: 07/18/2023]
Abstract
Endocytic dynamins self-assemble into helical scaffolds and utilize energy from GTP hydrolysis to constrict and sever tubular membranous necks of budded endocytic intermediates. They bind the membrane using a pleckstrin-homology domain (PHD). The PHD is characterized by four unstructured loops, two of which partially insert into the membrane. Recent studies reveal that loop insertion lowers the bending rigidity of the membrane and that mutations in these two loops produce separable and opposite effects on the efficiency of dynamin-catalyzed membrane fission. Here, we review the current understanding of dynamin-catalyzed membrane fission and attempt to reconcile contrasting notions that have emerged from biochemical and cellular studies evaluating the role of the PHD in this process. We propose that two membrane-inserting loops act as "gears" that define the catalytic efficiency of the dynamin helical scaffold in membrane fission.
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Affiliation(s)
- Himani Khurana
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008, Maharashtra, India
| | - Thomas J Pucadyil
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008, Maharashtra, India.
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4
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Fan F, Wu Y, Hara M, Rizk A, Ji C, Nerad D, Tamarina N, Lou X. Dynamin deficiency causes insulin secretion failure and hyperglycemia. Proc Natl Acad Sci U S A 2021; 118:e2021764118. [PMID: 34362840 PMCID: PMC8364113 DOI: 10.1073/pnas.2021764118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pancreatic β cells operate with a high rate of membrane recycling for insulin secretion, yet endocytosis in these cells is not fully understood. We investigate this process in mature mouse β cells by genetically deleting dynamin GTPase, the membrane fission machinery essential for clathrin-mediated endocytosis. Unexpectedly, the mice lacking all three dynamin genes (DNM1, DNM2, DNM3) in their β cells are viable, and their β cells still contain numerous insulin granules. Endocytosis in these β cells is severely impaired, resulting in abnormal endocytic intermediates on the plasma membrane. Although insulin granules are abundant, their release upon glucose stimulation is blunted in both the first and second phases, leading to hyperglycemia and glucose intolerance in mice. Dynamin triple deletion impairs insulin granule exocytosis and decreases intracellular Ca2+ responses and granule docking. The docking defect is correlated with reduced expression of Munc13-1 and RIM1 and reorganization of cortical F-actin in β cells. Collectively, these findings uncover the role of dynamin in dense-core vesicle endocytosis and secretory capacity. Insulin secretion deficiency in the absence of dynamin-mediated endocytosis highlights the risk of impaired membrane trafficking in endocrine failure and diabetes pathogenesis.
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Affiliation(s)
- Fan Fan
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Yumei Wu
- HHMI, Yale University School of Medicine, New Haven, CT 06510
- Departments of Neuroscience and Cell Biology, Program in Cellular Neuroscience, Neurodegeneration and Repair, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06510
| | - Manami Hara
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Chicago, Chicago, IL 60637
| | - Adam Rizk
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Chicago, Chicago, IL 60637
| | - Chen Ji
- Synapses and Circuits section, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892
| | - Dan Nerad
- Emergency Medicine, Carl R. Darnall Army Medical Center, Fort Hood, TX 76544
| | - Natalia Tamarina
- Department of Medicine, The Kovler Diabetes Center, University of Chicago, Chicago, IL 60637
| | - Xuelin Lou
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226;
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Sharafutdinov I, Backert S, Tegtmeyer N. Cortactin: A Major Cellular Target of the Gastric Carcinogen Helicobacter pylori. Cancers (Basel) 2020; 12:E159. [PMID: 31936446 PMCID: PMC7017262 DOI: 10.3390/cancers12010159] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/04/2020] [Accepted: 01/06/2020] [Indexed: 12/19/2022] Open
Abstract
Cortactin is an actin binding protein and actin nucleation promoting factor regulating cytoskeletal rearrangements in nearly all eukaryotic cell types. From this perspective, cortactin poses an attractive target for pathogens to manipulate a given host cell to their own benefit. One of the pathogens following this strategy is Helicobacter pylori, which can cause a variety of gastric diseases and has been shown to be the major risk factor for the onset of gastric cancer. During infection of gastric epithelial cells, H. pylori hijacks the cellular kinase signaling pathways, leading to the disruption of key cell functions. Specifically, by overruling the phosphorylation status of cortactin, H. pylori alternates the activity of molecular interaction partners of this important protein, thereby manipulating the performance of actin-cytoskeletal rearrangements and cell movement. In addition, H. pylori utilizes a unique mechanism to activate focal adhesion kinase, which subsequently prevents host epithelial cells from extensive lifting from the extracellular matrix in order to achieve chronic infection in the human stomach.
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Affiliation(s)
| | | | - Nicole Tegtmeyer
- Division of Microbiology, Department of Biology, Friedrich Alexander University Erlangen-Nuremberg, Staudtstr. 5, D-91058 Erlangen, Germany; (I.S.); (S.B.)
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6
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Mao XW, Sandberg LB, Gridley DS, Herrmann EC, Zhang G, Raghavan R, Zubarev RA, Zhang B, Stodieck LS, Ferguson VL, Bateman TA, Pecaut MJ. Proteomic Analysis of Mouse Brain Subjected to Spaceflight. Int J Mol Sci 2018; 20:ijms20010007. [PMID: 30577490 PMCID: PMC6337482 DOI: 10.3390/ijms20010007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/11/2018] [Accepted: 12/17/2018] [Indexed: 01/01/2023] Open
Abstract
There is evidence that spaceflight poses acute and late risks to the central nervous system. To explore possible mechanisms, the proteomic changes following spaceflight in mouse brain were characterized. Space Shuttle Atlantis (STS-135) was launched from the Kennedy Space Center (KSC) on a 13-day mission. Within 3–5 h after landing, brain tissue was collected to evaluate protein expression profiles using quantitative proteomic analysis. Our results showed that there were 26 proteins that were significantly altered after spaceflight in the gray and/or white matter. While there was no overlap between the white and gray matter in terms of individual proteins, there was overlap in terms of function, synaptic plasticity, vesical activity, protein/organelle transport, and metabolism. Our data demonstrate that exposure to the spaceflight environment induces significant changes in protein expression related to neuronal structure and metabolic function. This might lead to a significant impact on brain structural and functional integrity that could affect the outcome of space missions.
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Affiliation(s)
- Xiao Wen Mao
- Department of Basic Sciences, Division of Biomedical Engineering Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA.
| | - Lawrence B Sandberg
- Department of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
| | - Daila S Gridley
- Department of Basic Sciences, Division of Biomedical Engineering Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA.
| | - E Clifford Herrmann
- Department of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
| | - Guangyu Zhang
- Department of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
| | - Ravi Raghavan
- Department of Pathology and Human Anatomy, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
| | - Roman A Zubarev
- Department of Medical Biochemistry and Biophysics, Biomedicum, Karolinska Institutet, SE 17177 Stockholm, Sweden.
- Department of Pharmacological and Technological Chemistry, I.M. Sechenov First Moscow State Medical University, Moscow 119991, Russia.
| | - Bo Zhang
- Department of Medical Biochemistry and Biophysics, Biomedicum, Karolinska Institutet, SE 17177 Stockholm, Sweden.
- Department of Pharmacological and Technological Chemistry, I.M. Sechenov First Moscow State Medical University, Moscow 119991, Russia.
| | - Louis S Stodieck
- BioServe Space Technologies, University of Colorado at Boulder, Boulder, CO 80303, USA.
| | - Virginia L Ferguson
- BioServe Space Technologies, University of Colorado at Boulder, Boulder, CO 80303, USA.
| | - Ted A Bateman
- Department of Bioengineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Michael J Pecaut
- Department of Basic Sciences, Division of Biomedical Engineering Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA.
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Dynamin 1- and 3-Mediated Endocytosis Is Essential for the Development of a Large Central Synapse In Vivo. J Neurosci 2017; 36:6097-115. [PMID: 27251629 DOI: 10.1523/jneurosci.3804-15.2016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Accepted: 04/25/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Dynamin is a large GTPase crucial for endocytosis and sustained neurotransmission, but its role in synapse development in the mammalian brain has received little attention. We addressed this question using the calyx of Held (CH), a large nerve terminal in the auditory brainstem in mice. Tissue-specific ablation of different dynamin isoforms bypasses the early lethality of conventional knock-outs and allows us to examine CH development in a native brain circuit. Individual gene deletion of dynamin 1, a primary dynamin isoform in neurons, as well as dynamin 2 and 3, did not affect CH development. However, combined tissue-specific knock-out of both dynamin 1 and 3 (cDKO) severely impaired CH formation and growth during the first postnatal week, and the phenotypes were exacerbated by further additive conditional knock-out of dynamin 2. The developmental defect of CH in cDKO first became evident on postnatal day 3 (P3), a time point when CH forms and grows abruptly. This is followed by a progressive loss of postsynaptic neurons and increased glial infiltration late in development. However, early CH synaptogenesis before protocalyx formation was not altered in cDKO. Functional maturation of synaptic transmission in the medial nucleus of the trapezoid body in cDKO was impeded during development and accompanied by an increase in the membrane excitability of medial nucleus of the trapezoid body neurons. This study provides compelling genetic evidence that CH formation requires dynamin 1- and 3-mediated endocytosis in vivo, indicating a critical role of dynamin in synaptic development, maturation, and subsequent maintenance in the mammalian brain. SIGNIFICANCE STATEMENT Synaptic development has been increasingly implicated in numerous brain disorders. Dynamin plays a crucial role in clathrin-mediated endocytosis and synaptic transmission at nerve terminals, but its potential role in synaptic development in the native brain circuitry is unclear. Using the calyx of Held, a giant nerve terminal in the mouse brainstem, we evaluated the role of dynamin in this process by using tissue-specific knock-out (KO) of three different dynamin isoforms (dynamin 1, 2, and 3) individually and in combination. Our data demonstrated that dynamin is required for the formation, functional maturation, and subsequent survival of the calyx of Held. This study highlights the important role of dynamin-mediated endocytosis in the development of central synapses in the mammalian brain.
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Edwards BS, Clay CM, Ellsworth BS, Navratil AM. Functional Role of Gonadotrope Plasticity and Network Organization. Front Endocrinol (Lausanne) 2017; 8:223. [PMID: 28936197 PMCID: PMC5595155 DOI: 10.3389/fendo.2017.00223] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 08/16/2017] [Indexed: 11/18/2022] Open
Abstract
Gonadotrope cells of the anterior pituitary are characterized by their ability to mount a cyclical pattern of gonadotropin secretion to regulate gonadal function and fertility. Recent in vitro and in vivo evidence suggests that gonadotropes exhibit dramatic remodeling of the actin cytoskeleton following gonadotropin-releasing hormone (GnRH) exposure. GnRH engagement of actin is critical for gonadotrope function on multiple levels. First, GnRH-induced cell movements lead to spatial repositioning of the in vivo gonadotrope network toward vascular endothelium, presumably to access the bloodstream for effective hormone release. Interestingly, these plasticity changes can be modified depending on the physiological status of the organism. Additionally, GnRH-induced actin assembly appears to be fundamental to gonadotrope signaling at the level of extracellular signal-regulated kinase (ERK) activation, which is a well-known regulator of luteinizing hormone (LH) β-subunit synthesis. Last, GnRH-induced cell membrane projections are capable of concentrating LHβ-containing vesicles and disruption of the actin cytoskeleton reduces LH secretion. Taken together, gonadotrope network positioning and LH synthesis and secretion are linked to GnRH engagement of the actin cytoskeleton. In this review, we will cover the dynamics and organization of the in vivo gonadotrope cell network and the mechanisms of GnRH-induced actin-remodeling events important in ERK activation and subsequently hormone secretion.
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Affiliation(s)
- Brian S. Edwards
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, United States
| | - Colin M. Clay
- Department of Biomedical Science, Colorado State University, Fort Collins, CO, United States
| | - Buffy S. Ellsworth
- Department of Physiology, Southern Illinois University Carbondale, Carbondale, IL, United States
| | - Amy M. Navratil
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, United States
- *Correspondence: Amy M. Navratil,
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Trinh J, Gustavsson EK, Vilariño-Güell C, Bortnick S, Latourelle J, McKenzie MB, Tu CS, Nosova E, Khinda J, Milnerwood A, Lesage S, Brice A, Tazir M, Aasly JO, Parkkinen L, Haytural H, Foroud T, Myers RH, Sassi SB, Hentati E, Nabli F, Farhat E, Amouri R, Hentati F, Farrer MJ. DNM3 and genetic modifiers of age of onset in LRRK2 Gly2019Ser parkinsonism: a genome-wide linkage and association study. Lancet Neurol 2016; 15:1248-1256. [PMID: 27692902 DOI: 10.1016/s1474-4422(16)30203-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 07/28/2016] [Accepted: 08/04/2016] [Indexed: 12/31/2022]
Abstract
BACKGROUND Leucine-rich repeat kinase 2 (LRRK2) mutation 6055G→A (Gly2019Ser) accounts for roughly 1% of patients with Parkinson's disease in white populations, 13-30% in Ashkenazi Jewish populations, and 30-40% in North African Arab-Berber populations, although age of onset is variable. Some carriers have early-onset parkinsonism, whereas others remain asymptomatic despite advanced age. We aimed to use a genome-wide approach to identify genetic variability that directly affects LRRK2 Gly2019Ser penetrance. METHODS Between 2006 and 2012, we recruited Arab-Berber patients with Parkinson's disease and their family members (aged 18 years or older) at the Mongi Ben Hamida National Institute of Neurology (Tunis, Tunisia). Patients with Parkinson's disease were diagnosed by movement disorder specialists in accordance with the UK Parkinson's Disease Society Brain Bank criteria, without exclusion of familial parkinsonism. LRRK2 carrier status was confirmed by Sanger sequencing or TaqMan SNP assays-on-demand. We did genome-wide linkage analysis using data from multi-incident Arab-Berber families with Parkinson's disease and LRRK2 Gly2019Ser (with both affected and unaffected family members). We assessed Parkinson's disease age of onset both as a categorical variable (dichotomised by median onset) and as a quantitative trait. We used data from another cohort of unrelated Tunisian LRRK2 Gly2019Ser carriers for subsequent locus-specific genotyping and association analyses. Whole-genome sequencing in a subset of 14 unrelated Arab-Berber individuals who were LRRK2 Gly2019Ser carriers (seven with early-onset disease and seven elderly unaffected individuals) subsequently informed imputation and haplotype analyses. We replicated the findings in separate series of LRRK2 Gly2019Ser carriers originating from Algeria, France, Norway, and North America. We also investigated associations between genotype, gene, and protein expression in human striatal tissues and murine LRRK2 Gly2019Ser cortical neurons. FINDINGS Using data from 41 multi-incident Arab-Berber families with Parkinson's disease and LRRK2 Gly2019Ser (150 patients and 103 unaffected family members), we identified significant linkage on chromosome 1q23.3 to 1q24.3 (non-parametric logarithm of odds score 2·9, model-based logarithm of odds score 4·99, θ=0 at D1S2768). In a cohort of unrelated Arab-Berber LRRK2 Gly2019Ser carriers, subsequent association mapping within the linkage region suggested genetic variability within DNM3 as an age-of-onset modifier of disease (n=232; rs2421947; haplotype p=1·07 × 10-7). We found that DNM3 rs2421947 was a haplotype tag for which the median onset of LRRK2 parkinsonism in GG carriers was 12·5 years younger than that of CC carriers (Arab-Berber cohort, hazard ratio [HR] 1·89, 95% CI 1·20-2·98). Replication analyses in separate series from Algeria, France, Norway, and North America (n=263) supported this finding (meta-analysis HR 1·61, 95% CI 1·15-2·27, p=0·02). In human striatum, DNM3 expression varied as a function of rs2421947 genotype, and dynamin-3 localisation was perturbed in murine LRRK2 Gly2019Ser cortical neurons. INTERPRETATION Genetic variability in DNM3 modifies age of onset for LRRK2 Gly2019Ser parkinsonism and informs disease-relevant translational neuroscience. Our results could be useful in genetic counselling for carriers of this mutation and in clinical trial design. FUNDING The Canada Excellence Research Chairs (CERC), Leading Edge Endowment Fund (LEEF), Don Rix BC Leadership Chair in Genetic Medicine, National Institute on Aging, National Institute of Neurological Disorders and Stroke, the Michael J Fox Foundation, Mayo Foundation, the Roger de Spoelberch Foundation, and GlaxoSmithKline.
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Affiliation(s)
- Joanne Trinh
- Centre for Applied Neurogenetics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Emil K Gustavsson
- Centre for Applied Neurogenetics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; Department of Neurology, St Olav's Hospital, Trondheim, Norway
| | - Carles Vilariño-Güell
- Centre for Applied Neurogenetics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Stephanie Bortnick
- Centre for Applied Neurogenetics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Jeanne Latourelle
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| | - Marna B McKenzie
- Centre for Applied Neurogenetics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Chelsea Szu Tu
- Centre for Applied Neurogenetics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Ekaterina Nosova
- Centre for Applied Neurogenetics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Jaskaran Khinda
- Centre for Applied Neurogenetics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Austen Milnerwood
- Centre for Applied Neurogenetics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Suzanne Lesage
- Sorbonne Universités, UPMC Univ Paris 6 UMR S 1127, Inserm U 1127, CNRS UMR 7225, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Alexis Brice
- Sorbonne Universités, UPMC Univ Paris 6 UMR S 1127, Inserm U 1127, CNRS UMR 7225, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France; AP-HP, Hôpital de la Salpêtrière, Department of Genetics and Cytogenetics, Paris, France
| | - Meriem Tazir
- Service de Neurologie CHU Mustapha, Alger, Algeria
| | - Jan O Aasly
- Department of Neurology, St Olav's Hospital, Trondheim, Norway
| | - Laura Parkkinen
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Hazal Haytural
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Tatiana Foroud
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Richard H Myers
- Genome Science Institute, Boston University School of Medicine, Boston, MA, USA
| | - Samia Ben Sassi
- Mongi Ben Hamida National Institute of Neurology, La Rabta, Tunis, Tunisia
| | - Emna Hentati
- Mongi Ben Hamida National Institute of Neurology, La Rabta, Tunis, Tunisia
| | - Fatma Nabli
- Mongi Ben Hamida National Institute of Neurology, La Rabta, Tunis, Tunisia
| | - Emna Farhat
- Mongi Ben Hamida National Institute of Neurology, La Rabta, Tunis, Tunisia
| | - Rim Amouri
- Mongi Ben Hamida National Institute of Neurology, La Rabta, Tunis, Tunisia
| | - Fayçal Hentati
- Mongi Ben Hamida National Institute of Neurology, La Rabta, Tunis, Tunisia
| | - Matthew J Farrer
- Centre for Applied Neurogenetics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.
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10
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Mitra S, Sameer Kumar GS, Tiwari V, Lakshmi BJ, Thakur SS, Kumar S. Implication of Genetic Deletion of Wdr13 in Mice: Mild Anxiety, Better Performance in Spatial Memory Task, with Upregulation of Multiple Synaptic Proteins. Front Mol Neurosci 2016; 9:73. [PMID: 27625594 PMCID: PMC5003927 DOI: 10.3389/fnmol.2016.00073] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Accepted: 08/08/2016] [Indexed: 11/29/2022] Open
Abstract
WDR13 expresses from the X chromosome and has a highly conserved coding sequence. There have been multiple associations of WDR13 with memory. However, its detailed function in context of brain and behavior remains unknown. We characterized the behavioral phenotype of 2 month old male mice lacking the homolog of WDR13 gene (Wdr13−/0). Taking cue from analysis of its expression in the brain, we chose hippocampus for molecular studies to delineate its function. Wdr13−/0 mice spent less time in the central area of the open field test (OFT) and with the novel object in novel object recognition test (NOR) as compared to the wild-type. However, these mice didn't show any significant changes in total time spent in arms or in frequency of arm entries in elevated plus maze (EPM). In the absence of Wdr13, there was a significant upregulation of synaptic proteins, viz., SYN1, RAB3A, CAMK2A etc. accompanied with increased spine density of hippocampal CA1 neurons and better spatial memory in mice as measured by increased time spent in the target quadrant of Morris water maze (MWM) during probe test. Parallel study from our lab has established c-JUN, ER α/β, and HDAC 1,3,7 as interacting partners of WDR13. WDR13 represses transcription from AP1 (c-JUN responsive) and Estrogen Receptor Element (ERE) promoters. We hypothesized that absence of Wdr13 would result in de-regulated expression of a number of genes including multiple synaptic genes leading to the observed phenotype. Knocking down Wdr13 in Neuro2a cell lines led to increased transcripts of Camk2a and Nrxn2 consistent with in-vivo results. Summarily, our data provides functional evidence for the role of Wdr13 in brain.
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Affiliation(s)
- Shiladitya Mitra
- Council of Scientific and Industrial Research - Centre for Cellular and Molecular Biology Hyderabad, India
| | - Ghantasala S Sameer Kumar
- Council of Scientific and Industrial Research - Centre for Cellular and Molecular Biology Hyderabad, India
| | - Vivek Tiwari
- Council of Scientific and Industrial Research - Centre for Cellular and Molecular Biology Hyderabad, India
| | - B Jyothi Lakshmi
- Council of Scientific and Industrial Research - Centre for Cellular and Molecular Biology Hyderabad, India
| | - Suman S Thakur
- Council of Scientific and Industrial Research - Centre for Cellular and Molecular Biology Hyderabad, India
| | - Satish Kumar
- Council of Scientific and Industrial Research - Centre for Cellular and Molecular Biology Hyderabad, India
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11
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Ali M, Heyob K, Jacob NK, Rogers LK. Alterative Expression and Localization of Profilin 1/VASPpS157 and Cofilin 1/VASPpS239 Regulates Metastatic Growth and Is Modified by DHA Supplementation. Mol Cancer Ther 2016; 15:2220-31. [PMID: 27496138 DOI: 10.1158/1535-7163.mct-16-0092] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 06/23/2016] [Indexed: 01/26/2023]
Abstract
Profilin 1, cofilin 1, and vasodialator-stimulated phosphoprotein (VASP) are actin-binding proteins (ABP) that regulate actin remodeling and facilitate cancer cell metastases. miR-17-92 is highly expressed in metastatic tumors and profilin1 and cofilin1 are predicted targets. Docosahexaenoic acid (DHA) inhibits cancer cell proliferation and adhesion. These studies tested the hypothesis that the metastatic phenotype is driven by changes in ABPs including alternative phosphorylation and/or changes in subcellular localization. In addition, we tested the efficacy of DHA supplementation to attenuate or inhibit these changes. Human lung cancer tissue sections were analyzed for F-actin content and expression and cellular localization of profilin1, cofilin1, and VASP (S157 or S239 phosphorylation). The metastatic phenotype was investigated in A549 and MLE12 cells lines using 8 Br-cAMP as a metastasis inducer and DHA as a therapeutic agent. Migration was assessed by wound assay and expression measured by Western blot and confocal analysis. miR-17-92 expression was measured by qRT-PCR. Results indicated increased expression and altered cellular distribution of profilin1/VASP(pS157), but no changes in cofilin1/VASP(pS239) in the human malignant tissues compared with normal tissues. In A549 and MLE12 cells, the expression patterns of profilin1/VASP(pS157) or cofilin1/VASP(pS239) suggested an interaction in regulation of actin dynamics. Furthermore, DHA inhibited cancer cell migration and viability, ABP expression and cellular localization, and modulated expression of miR-17-92 in A549 cells with minimal effects in MLE12 cells. Further investigations are warranted to understand ABP interactions, changes in cellular localization, regulation by miR-17-92, and DHA as a novel therapeutic. Mol Cancer Ther; 15(9); 2220-31. ©2016 AACR.
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Affiliation(s)
- Mehboob Ali
- Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio.
| | - Kathryn Heyob
- Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio
| | | | - Lynette K Rogers
- Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio. Department of Pediatrics, The Ohio State University, Columbus, Ohio
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12
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Edwards BS, Dang AK, Murtazina DA, Dozier MG, Whitesell JD, Khan SA, Cherrington BD, Amberg GC, Clay CM, Navratil AM. Dynamin Is Required for GnRH Signaling to L-Type Calcium Channels and Activation of ERK. Endocrinology 2016; 157:831-43. [PMID: 26696122 PMCID: PMC4733113 DOI: 10.1210/en.2015-1575] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have shown that GnRH-mediated engagement of the cytoskeleton induces cell movement and is necessary for ERK activation. It also has previously been established that a dominant negative form of the mechano-GTPase dynamin (K44A) attenuates GnRH activation of ERK. At present, it is not clear at what level these cellular events might be linked. To explore this, we used live cell imaging in the gonadotrope-derived αT3-1 cell line to determine that dynamin-green fluorescent protein accumulated in GnRH-induced lamellipodia and plasma membrane protrusions. Coincident with translocation of dynamin-green fluorescent protein to the plasma membrane, we demonstrated that dynamin colocalizes with the actin cytoskeleton and the actin binding protein, cortactin at the leading edge of the plasma membrane. We next wanted to assess the physiological significance of these findings by inhibiting dynamin GTPase activity using dynasore. We find that dynasore suppresses activation of ERK, but not c-Jun N-terminal kinase, after exposure to GnRH agonist. Furthermore, exposure of αT3-1 cells to dynasore inhibited GnRH-induced cyto-architectural rearrangements. Recently it has been discovered that GnRH induced Ca(2+) influx via the L-type Ca(2+) channels requires an intact cytoskeleton to mediate ERK phosphorylation. Interestingly, not only does dynasore attenuate GnRH-mediated actin reorganization, it also suppresses Ca(2+) influx through L-type Ca(2+) channels visualized in living cells using total internal reflection fluorescence microscopy. Collectively, our data suggest that GnRH-induced membrane remodeling events are mediated in part by the association of dynamin and cortactin engaging the actin cytoskeleton, which then regulates Ca(2+) influx via L-type channels to facilitate ERK phosphorylation.
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Affiliation(s)
- Brian S Edwards
- Department of Zoology and Physiology (B.S.E., M.G.D., S.A.K., B.D.C., A.M.N.), University of Wyoming, Laramie, Wyoming 82071; Department of Biomedical Sciences (A.K.D., D.A.M., G.C.A., C.M.C.), Colorado State University, Fort Collins, Colorado 80523; and Department of Research and Development (J.D.W.), Allen Institute for Brain Science, Seattle, Washington 98103
| | - An K Dang
- Department of Zoology and Physiology (B.S.E., M.G.D., S.A.K., B.D.C., A.M.N.), University of Wyoming, Laramie, Wyoming 82071; Department of Biomedical Sciences (A.K.D., D.A.M., G.C.A., C.M.C.), Colorado State University, Fort Collins, Colorado 80523; and Department of Research and Development (J.D.W.), Allen Institute for Brain Science, Seattle, Washington 98103
| | - Dilyara A Murtazina
- Department of Zoology and Physiology (B.S.E., M.G.D., S.A.K., B.D.C., A.M.N.), University of Wyoming, Laramie, Wyoming 82071; Department of Biomedical Sciences (A.K.D., D.A.M., G.C.A., C.M.C.), Colorado State University, Fort Collins, Colorado 80523; and Department of Research and Development (J.D.W.), Allen Institute for Brain Science, Seattle, Washington 98103
| | - Melissa G Dozier
- Department of Zoology and Physiology (B.S.E., M.G.D., S.A.K., B.D.C., A.M.N.), University of Wyoming, Laramie, Wyoming 82071; Department of Biomedical Sciences (A.K.D., D.A.M., G.C.A., C.M.C.), Colorado State University, Fort Collins, Colorado 80523; and Department of Research and Development (J.D.W.), Allen Institute for Brain Science, Seattle, Washington 98103
| | - Jennifer D Whitesell
- Department of Zoology and Physiology (B.S.E., M.G.D., S.A.K., B.D.C., A.M.N.), University of Wyoming, Laramie, Wyoming 82071; Department of Biomedical Sciences (A.K.D., D.A.M., G.C.A., C.M.C.), Colorado State University, Fort Collins, Colorado 80523; and Department of Research and Development (J.D.W.), Allen Institute for Brain Science, Seattle, Washington 98103
| | - Shaihla A Khan
- Department of Zoology and Physiology (B.S.E., M.G.D., S.A.K., B.D.C., A.M.N.), University of Wyoming, Laramie, Wyoming 82071; Department of Biomedical Sciences (A.K.D., D.A.M., G.C.A., C.M.C.), Colorado State University, Fort Collins, Colorado 80523; and Department of Research and Development (J.D.W.), Allen Institute for Brain Science, Seattle, Washington 98103
| | - Brian D Cherrington
- Department of Zoology and Physiology (B.S.E., M.G.D., S.A.K., B.D.C., A.M.N.), University of Wyoming, Laramie, Wyoming 82071; Department of Biomedical Sciences (A.K.D., D.A.M., G.C.A., C.M.C.), Colorado State University, Fort Collins, Colorado 80523; and Department of Research and Development (J.D.W.), Allen Institute for Brain Science, Seattle, Washington 98103
| | - Gregory C Amberg
- Department of Zoology and Physiology (B.S.E., M.G.D., S.A.K., B.D.C., A.M.N.), University of Wyoming, Laramie, Wyoming 82071; Department of Biomedical Sciences (A.K.D., D.A.M., G.C.A., C.M.C.), Colorado State University, Fort Collins, Colorado 80523; and Department of Research and Development (J.D.W.), Allen Institute for Brain Science, Seattle, Washington 98103
| | - Colin M Clay
- Department of Zoology and Physiology (B.S.E., M.G.D., S.A.K., B.D.C., A.M.N.), University of Wyoming, Laramie, Wyoming 82071; Department of Biomedical Sciences (A.K.D., D.A.M., G.C.A., C.M.C.), Colorado State University, Fort Collins, Colorado 80523; and Department of Research and Development (J.D.W.), Allen Institute for Brain Science, Seattle, Washington 98103
| | - Amy M Navratil
- Department of Zoology and Physiology (B.S.E., M.G.D., S.A.K., B.D.C., A.M.N.), University of Wyoming, Laramie, Wyoming 82071; Department of Biomedical Sciences (A.K.D., D.A.M., G.C.A., C.M.C.), Colorado State University, Fort Collins, Colorado 80523; and Department of Research and Development (J.D.W.), Allen Institute for Brain Science, Seattle, Washington 98103
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13
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Peters NC, Berg CA. Dynamin-mediated endocytosis is required for tube closure, cell intercalation, and biased apical expansion during epithelial tubulogenesis in the Drosophila ovary. Dev Biol 2015; 409:39-54. [PMID: 26542010 DOI: 10.1016/j.ydbio.2015.10.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 08/09/2015] [Accepted: 10/31/2015] [Indexed: 11/28/2022]
Abstract
Most metazoans are able to grow beyond a few hundred cells and to support differentiated tissues because they elaborate multicellular, epithelial tubes that are indispensable for nutrient and gas exchange. To identify and characterize the cellular behaviors and molecular mechanisms required for the morphogenesis of epithelial tubes (i.e., tubulogenesis), we have turned to the D. melanogaster ovary. Here, epithelia surrounding the developing egg chambers first pattern, then form and extend a set of simple, paired, epithelial tubes, the dorsal appendage (DA) tubes, and they create these structures in the absence of cell division or cell death. This genetically tractable system lets us assess the relative contributions that coordinated changes in cell shape, adhesion, orientation, and migration make to basic epithelial tubulogenesis. We find that Dynamin, a conserved regulator of endocytosis and the cytoskeleton, serves a key role in DA tubulogenesis. We demonstrate that Dynamin is required for distinct aspects of DA tubulogenesis: DA-tube closure, DA-tube-cell intercalation, and biased apical-luminal cell expansion. We provide evidence that Dynamin promotes these processes by facilitating endocytosis of cell-cell and cell-matrix adhesion complexes, and we find that precise levels and sub-cellular distribution of E-Cadherin and specific Integrin subunits impact DA tubulogenesis. Thus, our studies identify novel morphogenetic roles (i.e., tube closure and biased apical expansion), and expand upon established roles (i.e., cell intercalation and adhesion remodeling), for Dynamin in tubulogenesis.
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Affiliation(s)
- Nathaniel C Peters
- University of Washington, Molecular and Cellular Biology Program and Department of Genome Sciences, Box 355065, Seattle, WA 98195-5065, United States
| | - Celeste A Berg
- University of Washington, Molecular and Cellular Biology Program and Department of Genome Sciences, Box 355065, Seattle, WA 98195-5065, United States.
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14
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Lomash RM, Gu X, Youle RJ, Lu W, Roche KW. Neurolastin, a Dynamin Family GTPase, Regulates Excitatory Synapses and Spine Density. Cell Rep 2015. [PMID: 26212327 DOI: 10.1016/j.celrep.2015.06.064] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Membrane trafficking and spinogenesis contribute significantly to changes in synaptic strength during development and in various paradigms of synaptic plasticity. GTPases of the dynamin family are key players regulating membrane trafficking. Here, we identify a brain-specific dynamin family GTPase, neurolastin (RNF112/Znf179), with closest homology to atlastin. We demonstrate that neurolastin has functional GTPase and RING domains, making it a unique protein identified with this multi-enzymatic domain organization. We also show that neurolastin is a peripheral membrane protein that localizes to endosomes and affects endosomal membrane dynamics via its RING domain. In addition, neurolastin knockout mice have fewer dendritic spines, and rescue of the wild-type phenotype requires both the GTPase and RING domains. Furthermore, we find fewer functional synapses and reduced paired pulse facilitation in neurolastin knockout mice. Thus, we identify neurolastin as a dynamin family GTPase that affects endosome size and spine density.
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Affiliation(s)
- Richa Madan Lomash
- Receptor Biology Section, National Institute of Neurological Disorders and Stroke (NINDS), NIH, Bethesda, MD 20892, USA
| | - Xinglong Gu
- Synapse and Neural Circuit Research Unit, NINDS, NIH, Bethesda, MD 20892, USA
| | - Richard J Youle
- Surgical Neurology Branch, NINDS, NIH, Bethesda, MD 20892, USA
| | - Wei Lu
- Synapse and Neural Circuit Research Unit, NINDS, NIH, Bethesda, MD 20892, USA
| | - Katherine W Roche
- Receptor Biology Section, National Institute of Neurological Disorders and Stroke (NINDS), NIH, Bethesda, MD 20892, USA.
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15
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Calabrese B, Halpain S. Differential targeting of dynamin-1 and dynamin-3 to nerve terminals during chronic suppression of neuronal activity. Mol Cell Neurosci 2015; 68:36-45. [PMID: 25827095 DOI: 10.1016/j.mcn.2015.03.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 03/17/2015] [Accepted: 03/24/2015] [Indexed: 01/14/2023] Open
Abstract
Neurons express three closely related dynamin genes. Dynamin 1 has long been implicated in the regulation of synaptic vesicle recycling in nerve terminals, and dynamins 2 and 3 were more recently shown also to contribute to synaptic vesicle recycling in specific and distinguishable ways. In cultured hippocampal neurons we found that chronic suppression of spontaneous network activity differentially regulated the targeting of endogenous dynamins 1 and 3 to nerve terminals, while dynamin 2 was unaffected. Specifically, when neural activity was chronically silenced for 1-2weeks by tetrodotoxin (TTX), the clustering of dynamin 1 at nerve terminals was reduced, while the clustering of dynamin 3 significantly increased. Moreover, dynamin 3 clustering was induced within hours by the sustained blockade of AMPA receptors, suggesting that AMPA receptors may function to prevent Dyn3 accumulation within nerve terminals. Clustering of dynamin 3 was induced by an antagonist of the calcium-dependent protein phosphatase calcineurin, but was not dependent upon intact actin filaments. TTX-induced clustering of Dyn3 occurred with a markedly slower time-course than the previously described clustering of synapsin 1. Potassium-induced depolarization rapidly de-clustered dynamin 3 from nerve terminals within minutes. These results, which have implications for homeostatic synapse restructuring, indicate that the three dynamins have evolved different regulatory mechanisms for trafficking to and from nerve terminals in response to changes in neural activity.
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Affiliation(s)
- Barbara Calabrese
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, United States; Sanford Consortium for Regenerative Medicine, University of California San Diego, La Jolla, CA, United States.
| | - Shelley Halpain
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, United States; Sanford Consortium for Regenerative Medicine, University of California San Diego, La Jolla, CA, United States.
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16
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Byers CE, Barylko B, Ross JA, Southworth DR, James NG, Taylor CA, Wang L, Collins KA, Estrada A, Waung M, Tassin TC, Huber KM, Jameson DM, Albanesi JP. Enhancement of dynamin polymerization and GTPase activity by Arc/Arg3.1. Biochim Biophys Acta Gen Subj 2015; 1850:1310-8. [PMID: 25783003 DOI: 10.1016/j.bbagen.2015.03.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 02/17/2015] [Accepted: 03/09/2015] [Indexed: 01/28/2023]
Abstract
BACKGROUND The Activity-regulated cytoskeleton-associated protein, Arc, is an immediate-early gene product implicated in various forms of synaptic plasticity. Arc promotes endocytosis of AMPA type glutamate receptors and regulates cytoskeletal assembly in neuronal dendrites. Its role in endocytosis may be mediated by its reported interaction with dynamin 2, a 100 kDa GTPase that polymerizes around the necks of budding vesicles and catalyzes membrane scission. METHODS Enzymatic and turbidity assays are used in this study to monitor effects of Arc on dynamin activity and polymerization. Arc oligomerization is measured using a combination of approaches, including size exclusion chromatography, sedimentation analysis, dynamic light scattering, fluorescence correlation spectroscopy, and electron microscopy. RESULTS We present evidence that bacterially-expressed His6-Arc facilitates the polymerization of dynamin 2 and stimulates its GTPase activity under physiologic conditions (37°C and 100mM NaCl). At lower ionic strength Arc also stabilizes pre-formed dynamin 2 polymers against GTP-dependent disassembly, thereby prolonging assembly-dependent GTP hydrolysis catalyzed by dynamin 2. Arc also increases the GTPase activity of dynamin 3, an isoform of implicated in dendrite remodeling, but does not affect the activity of dynamin 1, a neuron-specific isoform involved in synaptic vesicle recycling. We further show in this study that Arc (either His6-tagged or untagged) has a tendency to form large soluble oligomers, which may function as a scaffold for dynamin assembly and activation. CONCLUSIONS AND GENERAL SIGNIFICANCE The ability of Arc to enhance dynamin polymerization and GTPase activation may provide a mechanism to explain Arc-mediated endocytosis of AMPA receptors and the accompanying effects on synaptic plasticity.
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Affiliation(s)
- Christopher E Byers
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Barbara Barylko
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Justin A Ross
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 9681, United States
| | - Daniel R Southworth
- Department of Chemistry and Chemical Biology, University of California, San Francisco, CA 94158, United States
| | - Nicholas G James
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 9681, United States
| | - Clinton A Taylor
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Lei Wang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Katie A Collins
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Armando Estrada
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Maggie Waung
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Tara C Tassin
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Kimberly M Huber
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - David M Jameson
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 9681, United States
| | - Joseph P Albanesi
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States.
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17
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Chatron N, Haddad V, Andrieux J, Désir J, Boute O, Dieux A, Baumann C, Drunat S, Gérard M, Bonnet C, Leheup B, Till M, Rossi M, Flori E, Alembik Y, Stewart H, McParland J, Bernardini L, Castelluccio P, Roos L, Tümer Z, Fagan K, Hackett A, Bain N, van Haeringen A, Ruivenkamp C, Benzacken B, Sanlaville D, Edery P, Aboura A, Schluth-Bolard C. Refinement of genotype-phenotype correlation in 18 patients carrying a 1q24q25 deletion. Am J Med Genet A 2015; 167A:1008-17. [PMID: 25728055 DOI: 10.1002/ajmg.a.36856] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 10/07/2014] [Indexed: 11/10/2022]
Abstract
Interstitial deletion 1q24q25 is a rare rearrangement associated with intellectual disability, growth retardation, abnormal extremities and facial dysmorphism. In this study, we describe the largest series reported to date, including 18 patients (4M/14F) aged from 2 days to 67 years and comprising two familial cases. The patients presented with a characteristic phenotype including mild to moderate intellectual disability (100%), intrauterine (92%) and postnatal (94%) growth retardation, microcephaly (77%), short hands and feet (83%), brachydactyly (70%), fifth finger clinodactyly (78%) and facial dysmorphism with a bulbous nose (72%), abnormal ears (67%) and micrognathia (56%). Other findings were abnormal palate (50%), single transverse palmar crease (53%), renal (38%), cardiac (38%), and genital (23%) malformations. The deletions were characterized by chromosome microarray. They were of different sizes (490 kb to 20.95 Mb) localized within chromosome bands 1q23.3-q31.2 (chr1:160797550-192912120, hg19). The 490 kb deletion is the smallest deletion reported to date associated with this phenotype. We delineated three regions that may contribute to the phenotype: a proximal one (chr1:164,501,003-167,022,133), associated with cardiac and renal anomalies, a distal one (chr1:178,514,910-181,269,712) and an intermediate 490 kb region (chr1:171970575-172460683, hg19), deleted in the most of the patients, and containing DNM3, MIR3120 and MIR214 that may play an important role in the phenotype. However, this genetic region seems complex with multiple regions giving rise to the same phenotype.
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Affiliation(s)
- Nicolas Chatron
- Hospices Civils de Lyon, Service de Génétique, Laboratoire de Cytogénétique Constitutionnelle, Bron, France
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18
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Mimae T, Ito A. New challenges in pseudopodial proteomics by a laser-assisted cell etching technique. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1854:538-46. [PMID: 25461796 DOI: 10.1016/j.bbapap.2014.10.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 09/10/2014] [Accepted: 10/10/2014] [Indexed: 12/26/2022]
Abstract
Pseudopodia are ventral membrane protrusions that extend toward higher concentrations of chemoattractants and play key roles in cell migration and cancer cell invasion. Cancers, including carcinoma and sarcoma, become life threatening when they invade surrounding structures and other organs. Understanding the molecular basis of invasiveness is important for the elimination of cancers. Thus, determining the pseudopodial composition will offer insights into the mechanisms underlying tumor cell invasiveness and provide potential biomarkers and therapeutic targets. Pseudopodial composition has been extensively investigated by using proteomic approaches. A variety of modalities, including gel-based and mass spectrometry-based methods, have been employed for pseudopodial proteomics. Our research group recently established a novel method using excimer laser pulses to selectively harvest pseudopodia, and we successfully identified a number of new pseudopodial constituents. Here, we summarized the conventional proteomic procedures and describe our new excimer laser-assisted method, with a special emphasis on the differences in the methods used to isolate pseudopodia. In addition, we discussed the theoretical background for the use of excimer laser-mediated cell ablation in proteomic applications. Using the excimer laser-assisted method, we showed that alpha-parvin, an actin-binding adaptor protein, is localized to pseudopodia, and is involved in breast cancer invasiveness. Our results clearly indicate that excimer laser-assisted cell etching is a useful technique for pseudopodial proteomics. This article is part of a Special Issue entitled: Medical Proteomics.
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Affiliation(s)
- Takahiro Mimae
- Department of Surgical Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8551, Japan.
| | - Akihiko Ito
- Department of Pathology, Faculty of Medicine, Kinki University, Osaka 589-8511, Japan
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19
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Abstract
Among the largest cells in the body, neurons possess an immense surface area and intricate geometry that poses many unique cell biological challenges. This morphological complexity is critical for neural circuit formation and enables neurons to compartmentalize cell-cell communication and local intracellular signalling to a degree that surpasses other cell types. The adaptive plastic properties of neurons, synapses and circuits have been classically studied by measurement of electrophysiological properties, ionic conductances and excitability. Over the last 15 years, the field of synaptic and neural electrophysiology has collided with neuronal cell biology to produce a more integrated understanding of how these remarkable highly differentiated cells utilize common eukaryotic cellular machinery to decode, integrate and propagate signals in the nervous system. The present article gives a very brief and personal overview of the organelles and trafficking machinery of neuronal dendrites and their role in dendritic and synaptic plasticity.
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20
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González-Jamett AM, Haro-Acuña V, Momboisse F, Caviedes P, Bevilacqua JA, Cárdenas AM. Dynamin-2 in nervous system disorders. J Neurochem 2013; 128:210-23. [DOI: 10.1111/jnc.12455] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 09/04/2013] [Accepted: 09/12/2013] [Indexed: 12/21/2022]
Affiliation(s)
- Arlek M. González-Jamett
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso Chile
| | - Valentina Haro-Acuña
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso Chile
| | - Fanny Momboisse
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso Chile
| | - Pablo Caviedes
- Programa de Farmacología Molecular y Clínica; Facultad de Medicina; Universidad de Chile; Santiago Chile
| | - Jorge A. Bevilacqua
- Departamento de Neurología y Neurocirugía; Hospital Clínico Universidad de Chile; and Programa de Anatomía y Biología del Desarrollo; ICBM; Facultad de Medicina; Universidad de Chile; Santiago Chile
| | - Ana M. Cárdenas
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso Chile
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21
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Kelemen O, Convertini P, Zhang Z, Wen Y, Shen M, Falaleeva M, Stamm S. Function of alternative splicing. Gene 2013; 514:1-30. [PMID: 22909801 PMCID: PMC5632952 DOI: 10.1016/j.gene.2012.07.083] [Citation(s) in RCA: 514] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/21/2012] [Accepted: 07/30/2012] [Indexed: 12/15/2022]
Abstract
Almost all polymerase II transcripts undergo alternative pre-mRNA splicing. Here, we review the functions of alternative splicing events that have been experimentally determined. The overall function of alternative splicing is to increase the diversity of mRNAs expressed from the genome. Alternative splicing changes proteins encoded by mRNAs, which has profound functional effects. Experimental analysis of these protein isoforms showed that alternative splicing regulates binding between proteins, between proteins and nucleic acids as well as between proteins and membranes. Alternative splicing regulates the localization of proteins, their enzymatic properties and their interaction with ligands. In most cases, changes caused by individual splicing isoforms are small. However, cells typically coordinate numerous changes in 'splicing programs', which can have strong effects on cell proliferation, cell survival and properties of the nervous system. Due to its widespread usage and molecular versatility, alternative splicing emerges as a central element in gene regulation that interferes with almost every biological function analyzed.
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Affiliation(s)
- Olga Kelemen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Paolo Convertini
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zhaiyi Zhang
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Yuan Wen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Manli Shen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Marina Falaleeva
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Stefan Stamm
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
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22
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Inactivation of the microRNA-183/96/182 cluster results in syndromic retinal degeneration. Proc Natl Acad Sci U S A 2013; 110:E507-16. [PMID: 23341629 DOI: 10.1073/pnas.1212655110] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The microRNA-183/96/182 cluster is highly expressed in the retina and other sensory organs. To uncover its in vivo functions in the retina, we generated a knockout mouse model, designated "miR-183C(GT/GT)," using a gene-trap embryonic stem cell clone. We provide evidence that inactivation of the cluster results in early-onset and progressive synaptic defects of the photoreceptors, leading to abnormalities of scotopic and photopic electroretinograms with decreased b-wave amplitude as the primary defect and progressive retinal degeneration. In addition, inactivation of the miR-183/96/182 cluster resulted in global changes in retinal gene expression, with enrichment of genes important for synaptogenesis, synaptic transmission, photoreceptor morphogenesis, and phototransduction, suggesting that the miR-183/96/182 cluster plays important roles in postnatal functional differentiation and synaptic connectivity of photoreceptors.
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23
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Menon M, Schafer DA. Dynamin: expanding its scope to the cytoskeleton. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 302:187-219. [PMID: 23351711 DOI: 10.1016/b978-0-12-407699-0.00003-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The large GTPase dynamin is well known for its actions on budded cellular membranes to generate vesicles, most often, clathrin-coated endocytic vesicles. The scope of cellular processes in which dynamin-mediated vesicle formation occurs, has expanded to include secretory vesicle formation at the Golgi, from other endosomes and nonclathrin structures, such as caveolae, as well as membrane remodeling during exocytosis and vesicle fusion. An intriguing new facet of dynamin's sphere of influence is the cytoskeleton. Cytoskeletal filament networks maintain cell shape, provide cell movement, execute cell division and orchestrate vesicle trafficking. Recent evidence supports the hypothesis that dynamin influences actin filaments and microtubules via mechanisms that are independent of its membrane-remodeling activities. This chapter discusses this emerging evidence and considers possible mechanisms of action.
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Affiliation(s)
- Manisha Menon
- Department of Biology, University of Virginia, Charlottesville, VA, USA
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24
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Scott H, Howarth J, Lee YB, Wong LF, Bantounas I, Phylactou L, Verkade P, Uney JB. MiR-3120 is a mirror microRNA that targets heat shock cognate protein 70 and auxilin messenger RNAs and regulates clathrin vesicle uncoating. J Biol Chem 2012; 287:14726-33. [PMID: 22393045 PMCID: PMC3340243 DOI: 10.1074/jbc.m111.326041] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/28/2012] [Indexed: 12/27/2022] Open
Abstract
We show that a single gene locus gives rise to two fully processed and functional miRNAs, i.e. that due to imperfect base pairing, two distinct microRNAs (miRNAs) can be produced from the fully complementary DNA strands. The antisense strand encodes miR-214, which is transcribed by its own promoter, whereas a novel miRNA, miR-3120, is co-expressed with its host gene mRNA. We also found that miR-3120 regulates important aspects of cellular function that are similar to that of its host gene, dynamin-3. miR-3120 was found to be located in neuronal cell bodies and to target Hsc70 and auxilin, and its lentivirus-mediated expression inhibited the uncoating of clathrin-coated vesicles. Finally, mirror miRNAs are likely to represent a new group of miRNAs with complex roles in coordinating gene expression.
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Affiliation(s)
- Helen Scott
- From the Henry Wellcome Laboratories for Integrated Neuroscience and Endocrinology, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY
| | - Joanna Howarth
- From the Henry Wellcome Laboratories for Integrated Neuroscience and Endocrinology, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY
| | - Youn Bok Lee
- the Medical Research Council (MRC) Centre for Neurodegeneration Research, Institute of Psychiatry, King's College London, London SE5 8AF
| | - Liang-Fong Wong
- From the Henry Wellcome Laboratories for Integrated Neuroscience and Endocrinology, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY
| | - Ioannis Bantounas
- the Faculty of Life Sciences, University of Manchester, Michael Smith Building, Manchester M13 9PL
| | - Leonidas Phylactou
- the Department of Molecular Genetics Function and Therapy, The Cyprus Institute of Neurology and Genetics, 1683 Nicosia, Cyprus, and
| | - Paul Verkade
- the Schools of Biochemistry and Physiology and Pharmacology, University of Bristol, Wolfson Bioimaging Facility, Medical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - James. B. Uney
- From the Henry Wellcome Laboratories for Integrated Neuroscience and Endocrinology, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY
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25
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Wakita Y, Kakimoto T, Katoh H, Negishi M. The F-BAR protein Rapostlin regulates dendritic spine formation in hippocampal neurons. J Biol Chem 2011; 286:32672-83. [PMID: 21768103 DOI: 10.1074/jbc.m111.236265] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pombe Cdc15 homology proteins, characterized by Fer/CIP4 homology Bin-Amphiphysin-Rvs/extended Fer/CIP4 homology (F-BAR/EFC) domains with membrane invaginating property, play critical roles in a variety of membrane reorganization processes. Among them, Rapostlin/formin-binding protein 17 (FBP17) has attracted increasing attention as a critical coordinator of endocytosis. Here we found that Rapostlin was expressed in the developing rat brain, including the hippocampus, in late developmental stages when accelerated dendritic spine formation and maturation occur. In primary cultured rat hippocampal neurons, knockdown of Rapostlin by shRNA or overexpression of Rapostlin-QQ, an F-BAR domain mutant of Rapostlin that has no ability to induce membrane invagination, led to a significant decrease in spine density. Expression of shRNA-resistant wild-type Rapostlin effectively restored spine density in Rapostlin knockdown neurons, whereas expression of Rapostlin deletion mutants lacking the protein kinase C-related kinase homology region 1 (HR1) or Src homology 3 (SH3) domain did not. In addition, knockdown of Rapostlin or overexpression of Rapostlin-QQ reduced the uptake of transferrin in hippocampal neurons. Knockdown of Rnd2, which binds to the HR1 domain of Rapostlin, also reduced spine density and the transferrin uptake. These results suggest that Rapostlin and Rnd2 cooperatively regulate spine density. Indeed, Rnd2 enhanced the Rapostlin-induced tubular membrane invagination. We conclude that the F-BAR protein Rapostlin, whose activity is regulated by Rnd2, plays a key role in spine formation through the regulation of membrane dynamics.
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Affiliation(s)
- Yohei Wakita
- Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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26
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Ross JA, Chen Y, Müller J, Barylko B, Wang L, Banks HB, Albanesi JP, Jameson DM. Dimeric endophilin A2 stimulates assembly and GTPase activity of dynamin 2. Biophys J 2011; 100:729-737. [PMID: 21281588 DOI: 10.1016/j.bpj.2010.12.3717] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 12/02/2010] [Accepted: 12/14/2010] [Indexed: 10/18/2022] Open
Abstract
Endophilin, which participates in membrane vesiculation during receptor-mediated endocytosis, is a ∼40 kDa SH3 domain-containing protein that binds to the proline/arginine-rich domain of dynamin, a ∼100 kDa GTPase that is essential for endocytic membrane scission. It has been suggested that endophilin is monomeric in the cytoplasm and dimerizes only after it binds to membranes (or perhaps to dimers or tetramers of dynamin). To clarify this issue, we studied the oligomeric state of endophilin both in vitro using analytical ultracentrifugation and fluorescence anisotropy, and in living cells using two-photon fluorescence fluctuation spectroscopy. We analyzed the fluctuation data using the Q-analysis method, which allowed us to determine the intrinsic brightness of the labeled protein complexes and hence its aggregation state in the cytoplasmic regions of the cell. Although a relatively high K(d) (∼5-15 μM) was observed in vitro, the cell measurements indicate that endophilin is dimeric in the cytoplasm, even at submicromolar concentrations. We also demonstrate that endophilin significantly enhances the assembly of dynamin, and that this enhancement is proportional to the fraction of dimeric endophilin that is present. Moreover, there is correlation between the concentrations of endophilin that promote dynamin self-assembly and those that stimulate dynamin GTPase activity. These findings support the view that endophilin-dynamin interactions play an important role in endocytosis.
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Affiliation(s)
- Justin A Ross
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Yan Chen
- Physics Department, University of Minnesota, Minneapolis, Minnesota
| | - Joachim Müller
- Physics Department, University of Minnesota, Minneapolis, Minnesota
| | - Barbara Barylko
- Pharmacology Department, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Lei Wang
- Pharmacology Department, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Hunter B Banks
- Pharmacology Department, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Joseph P Albanesi
- Pharmacology Department, University of Texas Southwestern Medical Center, Dallas, Texas
| | - David M Jameson
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii.
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27
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Kurklinsky S, Chen J, McNiven MA. Growth cone morphology and spreading are regulated by a dynamin-cortactin complex at point contacts in hippocampal neurons. J Neurochem 2011; 117:48-60. [PMID: 21210813 DOI: 10.1111/j.1471-4159.2011.07169.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Neuronal growth cone (GC) migration and targeting are essential processes for the formation of a neural network during embryonic development. Currently, the mechanisms that support directed motility of GCs are not fully defined. The large GTPase dynamin and an interacting actin-binding protein, cortactin, have been localized to GCs, although the function performed by this complex is unclear. We have found that cortactin and the ubiquitous form of dynamin (Dyn) 2 exhibit a striking co-localization at the base of the transition zone of advancing GCs of embryonic hippocampal neurons. Confocal and total internal reflection fluorescence microscopies demonstrate that this basal localization represents point contacts. Exogenous expression of wild-type Dyn2 and cortactin leads to large, exceptionally flat, and static GCs, whereas disrupting this complex has no such effect. We find that excessive GC spreading is induced by Dyn2 and cortactin over-expression and substantial recruitment of the point contact-associated, actin-binding protein α-actinin1 to the ventral GC membrane. The distributions of other point contact proteins such as vinculin or paxillin appear unchanged. Immunoprecipitation experiments show that both Dyn2 and cortactin reside in a complex with α-actinin1. These findings provide new insights into the role of Dyn2 and the actin cytoskeleton in GC adhesion and motility.
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Affiliation(s)
- Svetlana Kurklinsky
- Mayo Graduate School, The Molecular Neuroscience Program, Rochester, Minnesota, USA
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28
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Barylko B, Wang L, Binns DD, Ross JA, Tassin TC, Collins KA, Jameson DM, Albanesi JP. The proline/arginine-rich domain is a major determinant of dynamin self-activation. Biochemistry 2010; 49:10592-4. [PMID: 21082776 DOI: 10.1021/bi101343p] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dynamins induce membrane vesiculation during endocytosis and Golgi budding in a process that requires assembly-dependent GTPase activation. Brain-specific dynamin 1 has a weaker propensity to self-assemble and self-activate than ubiquitously expressed dynamin 2. Here we show that dynamin 3, which has important functions in neuronal synapses, shares the self-assembly and GTPase activation characteristics of dynamin 2. Analysis of dynamin hybrids and of dynamin 1-dynamin 2 and dynamin 1-dynamin 3 heteropolymers reveals that concentration-dependent GTPase activation is suppressed by the C-terminal proline/arginine-rich domain of dynamin 1. Dynamin proline/arginine-rich domains also mediate interactions with SH3 domain-containing proteins and thus regulate both self-association and heteroassociation of dynamins.
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Affiliation(s)
- Barbara Barylko
- Department of Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75235-9041, United States
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29
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Pontrello CG, Ethell IM. Accelerators, Brakes, and Gears of Actin Dynamics in Dendritic Spines. ACTA ACUST UNITED AC 2009; 3:67-86. [PMID: 20463852 DOI: 10.2174/1874082000903020067] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Dendritic spines are actin-rich structures that accommodate the postsynaptic sites of most excitatory synapses in the brain. Although dendritic spines form and mature as synaptic connections develop, they remain plastic even in the adult brain, where they can rapidly grow, change, or collapse in response to normal physiological changes in synaptic activity that underlie learning and memory. Pathological stimuli can adversely affect dendritic spine shape and number, and this is seen in neurodegenerative disorders and some forms of mental retardation and autism as well. Many of the molecular signals that control these changes in dendritic spines act through the regulation of filamentous actin (F-actin), some through direct interaction with actin, and others via downstream effectors. For example, cortactin, cofilin, and gelsolin are actin-binding proteins that directly regulate actin dynamics in dendritic spines. Activities of these proteins are precisely regulated by intracellular signaling events that control their phosphorylation state and localization. In this review, we discuss how actin-regulating proteins maintain the balance between F-actin assembly and disassembly that is needed to stabilize mature dendritic spines, and how changes in their activities may lead to rapid remodeling of dendritic spines.
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Affiliation(s)
- Crystal G Pontrello
- Biomedical Sciences Division and Neuroscience program, University of California Riverside, USA
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30
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Mooren OL, Kotova TI, Moore AJ, Schafer DA. Dynamin2 GTPase and cortactin remodel actin filaments. J Biol Chem 2009; 284:23995-4005. [PMID: 19605363 DOI: 10.1074/jbc.m109.024398] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The large GTPase dynamin, best known for its activities that remodel membranes during endocytosis, also regulates F-actin-rich structures, including podosomes, phagocytic cups, actin comet tails, subcortical ruffles, and stress fibers. The mechanisms by which dynamin regulates actin filaments are not known, but an emerging view is that dynamin influences F-actin via its interactions with proteins that interact directly or indirectly with actin filaments. We show here that dynamin2 GTPase activity remodels actin filaments in vitro via a mechanism that depends on the binding partner and F-actin-binding protein, cortactin. Tightly associated actin filaments cross-linked by dynamin2 and cortactin became loosely associated after GTP addition when viewed by transmission electron microscopy. Actin filaments were dynamically unraveled and fragmented after GTP addition when viewed in real time using total internal reflection fluorescence microscopy. Cortactin stimulated the intrinsic GTPase activity of dynamin2 and maintained a stable link between actin filaments and dynamin2, even in the presence of GTP. Filaments remodeled by dynamin2 GTPase in vitro exhibit enhanced sensitivity to severing by the actin depolymerizing factor, cofilin, suggesting that GTPase-dependent remodeling influences the interactions of actin regulatory proteins and F-actin. The global organization of the actomyosin cytoskeleton was perturbed in U2-OS cells depleted of dynamin2, implicating dynamin2 in remodeling actin filaments that comprise supramolecular F-actin arrays in vivo. We conclude that dynamin2 GTPase remodels actin filaments and plays a role in orchestrating the global actomyosin cytoskeleton.
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Affiliation(s)
- Olivia L Mooren
- Department of Biology, University of Virginia, Charlottesville, Virginia 22903, USA
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31
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Neurite consolidation is an active process requiring constant repression of protrusive activity. EMBO J 2008; 28:248-60. [PMID: 19096364 DOI: 10.1038/emboj.2008.265] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Accepted: 11/25/2008] [Indexed: 01/05/2023] Open
Abstract
During development, neurons extend projections that pathfind to reach their appropriate targets. These projections are composed of two distinct domains: a highly dynamic growth cone and a stable neurite shaft, which is considered to be consolidated. Although the regulation of these domains is critical to the appropriate formation of neural networks, the molecular mechanisms that regulate neurite shape remain poorly understood. Here, we show that calpain protease activity localizes to the neurite shaft, where it is essential for the repression of protrusive activity by limiting cortactin levels and inhibiting actin polymerization. Correspondingly, inhibition of calpain by branching factors induces the formation of new growth cones along the neurite shaft through cAMP elevation. These findings demonstrate that neurite consolidation is an active process requiring constant repression of protrusive activity. We also show that sprouting is, at least in part, accomplished by turning off the mechanism of consolidation.
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32
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Ammer AG, Weed SA. Cortactin branches out: roles in regulating protrusive actin dynamics. ACTA ACUST UNITED AC 2008; 65:687-707. [PMID: 18615630 DOI: 10.1002/cm.20296] [Citation(s) in RCA: 210] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Since its discovery in the early 1990's, cortactin has emerged as a key signaling protein in many cellular processes, including cell adhesion, migration, endocytosis, and tumor invasion. While the list of cellular functions influenced by cortactin grows, the ability of cortactin to interact with and alter the cortical actin network is central to its role in regulating these processes. Recently, several advances have been made in our understanding of the interaction between actin and cortactin, providing insight into how these two proteins work together to provide a framework for normal and altered cellular function. This review examines how regulation of cortactin through post-translational modifications and interactions with multiple binding partners elicits changes in cortical actin cytoskeletal organization, impacting the regulation and formation of actin-rich motility structures.
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Affiliation(s)
- Amanda Gatesman Ammer
- Department of Neuroscience and Anatomy, Program in Cancer Cell Biology, Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, West Virginia 26506-9300, USA
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33
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Young JS, Guttman JA, Vaid KS, Shahinian H, Vogl AW. Cortactin (CTTN), N-WASP (WASL), and clathrin (CLTC) are present at podosome-like tubulobulbar complexes in the rat testis. Biol Reprod 2008; 80:153-61. [PMID: 18799755 DOI: 10.1095/biolreprod.108.070615] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Tubulobulbar complexes are actin filament-rich plasma membrane protrusions that form at intercellular junctions in the seminiferous epithelium of the mammalian testis. They are proposed to internalize intact junctions during sperm release and during the translocation of spermatocytes through basal junction complexes between neighboring Sertoli cells. Tubulobulbar complexes morphologically resemble podosomes found at cell/substrate attachments in other systems. In this study we probe apical tubulobulbar complexes in fixed epithelial fragments and fixed frozen sections of rat testis for two key actin-related components found at podosomes, and for the endocytosis-related protein clathrin. N-WASP and cortactin, two regulators of actin network assembly known to be components of podosomes, are concentrated at tubulobulbar complexes. Clathrin-positive structures occur in Sertoli cell regions containing tubulobulbar complexes when analyzed by immunofluorescence microscopy and occur at the ends of the complexes when evaluated by immunoelectron microscopy. Our results are consistent with the conclusion that tubulobulbar complexes are podosome-like structures. We propose that the formation of tubulobulbar complexes may be clathrin initiated and that their growth is due to the dendritic assembly of a membrane-related actin network.
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Affiliation(s)
- J'Nelle S Young
- Department of Cellular and Physiological Sciences, Faculty of Medicine, Life Sciences Centre, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
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34
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Newpher TM, Ehlers MD. Glutamate receptor dynamics in dendritic microdomains. Neuron 2008; 58:472-97. [PMID: 18498731 PMCID: PMC2572138 DOI: 10.1016/j.neuron.2008.04.030] [Citation(s) in RCA: 278] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 04/28/2008] [Accepted: 04/30/2008] [Indexed: 01/08/2023]
Abstract
Among diverse factors regulating excitatory synaptic transmission, the abundance of postsynaptic glutamate receptors figures prominently in molecular memory and learning-related synaptic plasticity. To allow for both long-term maintenance of synaptic transmission and acute changes in synaptic strength, the relative rates of glutamate receptor insertion and removal must be tightly regulated. Interactions with scaffolding proteins control the targeting and signaling properties of glutamate receptors within the postsynaptic membrane. In addition, extrasynaptic receptor populations control the equilibrium of receptor exchange at synapses and activate distinct signaling pathways involved in plasticity. Here, we review recent findings that have shaped our current understanding of receptor mobility between synaptic and extrasynaptic compartments at glutamatergic synapses, focusing on AMPA and NMDA receptors. We also examine the cooperative relationship between intracellular trafficking and surface diffusion of glutamate receptors that underlies the expression of learning-related synaptic plasticity.
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Affiliation(s)
- Thomas M. Newpher
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Michael D. Ehlers
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
- Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
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35
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Cell- and stimulus-dependent heterogeneity of synaptic vesicle endocytic recycling mechanisms revealed by studies of dynamin 1-null neurons. Proc Natl Acad Sci U S A 2008; 105:2175-80. [PMID: 18250322 DOI: 10.1073/pnas.0712171105] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mice lacking expression of dynamin 1, a GTPase implicated in the fission reaction of synaptic vesicle endocytosis, fail to thrive and exhibit severe activity-dependent endocytic defects at their synapses. Here, we have used electron tomography to investigate the massive increase in clathrin-coated pit abundance that is selectively observed at a subset of synapses in dynamin 1 KO primary neuron cultures under conditions of spontaneous network activity. This increase, leading to branched tubular plasma membrane invaginations capped by clathrin-coated buds, occurs selectively at inhibitory synapses. A similar massive increase of clathrin-coated profiles (in this case, of clathrin-coated vesicles) is observed at inhibitory synapses of neurons that lack expression of synaptojanin 1, a phosphoinositide phosphatase involved in clathrin-coated vesicle uncoating. Thus, although excitatory synapses are largely spared under these conditions, inhibitory synapses are uniquely sensitive to perturbation of endocytic proteins, probably as a result of their higher levels of tonic activity leading to a buildup of clathrin-coated intermediates in these synapses. In contrast, the predominant endocytic structures observed at the majority of dynamin 1 KO synapses after acute stimulation are endosome-like intermediates that originate by a dynamin 1-independent form of endocytosis. These findings reveal a striking heterogeneity in the mode of synaptic vesicle recycling in different synapses and functional states.
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36
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Cao H, Chen J, Awoniyi M, Henley JR, McNiven MA. Dynamin 2 mediates fluid-phase micropinocytosis in epithelial cells. J Cell Sci 2007; 120:4167-77. [PMID: 18003703 DOI: 10.1242/jcs.010686] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
It is well-known that dynamin 2 (Dyn2) participates in clathrin- and caveolae-mediated endocytosis; however, the role of Dyn2 in coat-independent endocytic processes remains controversial. Here we demonstrate a role for specific spliced variants of Dyn2 in the micropinocytosis of fluid in epithelial cells, independent of coat-mediated endocytic pathways. A general inhibition of Dyn2 was first performed using either microinjection of anti-dynamin antibodies or Dyn2-siRNA treatment. Both of these methods resulted in reduced uptake of transferrin, a marker for clathrin-mediated endocytosis, and, under unstimulated conditions, reduced the uptake of the fluid-phase markers dextran and horseradish peroxidase (HRP). By contrast, cells treated similarly but stimulated with serum or EGF internalized substantial amounts of dextran or HRP, indicating that Dyn2 is not required for stimulated fluid uptake via macropinocytosis. We next tested whether a specific spliced variant might selectively affect fluid-phase endocytosis. Mutation of specific Dyn2 spliced variants resulted in a differential attenuation of transferrin and dextran internalization. Furthermore, the reduction in fluid uptake in Dyn2-siRNA-treated cells was only rescued upon re-expression of select spliced variants. These findings suggest that Dyn2 function is required for the coat-independent internalization of fluid through endocytic pathways distinct from macropinocytosis and, in addition, implicate different Dyn2 spliced variants in specific endocytic functions.
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Affiliation(s)
- Hong Cao
- Mayo Clinic, Department of Biochemistry and Molecular Biology and the Miles and Shirley Fiterman Center for Digestive Diseases, Rochester, MN 55905, USA
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37
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Abstract
Endocytosis, exocytosis, and lateral diffusion are key mechanisms for AMPA receptor trafficking. Endocytosis of AMPARs and other postsynaptic proteins has been proposed to occur at specific endocytic zones (EZs), but the mechanisms that regulate this process are not at all clear. In this issue of Neuron, Lu et al. show that correct synaptic EZ positioning requires links between the GTPase dynamin-3 and the Homer/Shank complex.
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Affiliation(s)
- Frédéric Jaskolski
- MRC Centre for Synaptic Plasticity, Department of Anatomy, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Stéphane Martin
- MRC Centre for Synaptic Plasticity, Department of Anatomy, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Jeremy M. Henley
- MRC Centre for Synaptic Plasticity, Department of Anatomy, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
- Correspondence:
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Lu J, Helton TD, Blanpied TA, Rácz B, Newpher TM, Weinberg RJ, Ehlers MD. Postsynaptic positioning of endocytic zones and AMPA receptor cycling by physical coupling of dynamin-3 to Homer. Neuron 2007; 55:874-89. [PMID: 17880892 PMCID: PMC2597538 DOI: 10.1016/j.neuron.2007.06.041] [Citation(s) in RCA: 212] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Revised: 06/08/2007] [Accepted: 07/31/2007] [Indexed: 02/07/2023]
Abstract
Endocytosis of AMPA receptors and other postsynaptic cargo occurs at endocytic zones (EZs), stably positioned sites of clathrin adjacent to the postsynaptic density (PSD). The tight localization of postsynaptic endocytosis is thought to control spine composition and regulate synaptic transmission. However, the mechanisms that situate the EZ near the PSD and the role of spine endocytosis in synaptic transmission are unknown. Here, we report that a physical link between dynamin-3 and the postsynaptic adaptor Homer positions the EZ near the PSD. Disruption of dynamin-3 or its interaction with Homer uncouples the PSD from the EZ, resulting in synapses lacking postsynaptic clathrin. Loss of the EZ leads to a loss of synaptic AMPA receptors and reduced excitatory synaptic transmission that corresponds with impaired synaptic recycling. Thus, a physical link between the PSD and the EZ ensures localized endocytosis and recycling by recapturing and maintaining a proximate pool of cycling AMPA receptors.
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Affiliation(s)
- Jiuyi Lu
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Thomas D. Helton
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Thomas A. Blanpied
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Bence Rácz
- Department of Cell and Developmental Biology, University of North Carolina School of Medicine, Chapel Hill, NC, 27599, USA
| | - Thomas M. Newpher
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Richard J. Weinberg
- Department of Cell and Developmental Biology, University of North Carolina School of Medicine, Chapel Hill, NC, 27599, USA
- Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, NC, 27599, USA
| | - Michael D. Ehlers
- Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
- Corresponding Author: Michael D. Ehlers, M.D., Ph.D., Howard Hughes Medical Institute, Department of Neurobiology, Duke University Medical Center, Box 3209, Durham, NC 27710, USA, Tel: (919)684-1828, FAX (919)668-0631, e-mail:
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39
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Vaid KS, Guttman JA, Babyak N, Deng W, McNiven MA, Mochizuki N, Finlay BB, Vogl AW. The role of dynamin 3 in the testis. J Cell Physiol 2007; 210:644-54. [PMID: 17133358 DOI: 10.1002/jcp.20855] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We report here that dynamin 3 in the testis is associated with structures termed tubulobulbar complexes that internalize intact intercellular junctions during sperm release and turnover of the blood-testis barrier. The protein lies adjacent to an actin-Arp2/3 network that cuffs the double plasma membrane tubular invagination at the core of each complex. To explore the possible relationship between dynamin 3 and nectin-based adhesion junctions, we transiently transfected DsRed-tagged dynamin 3 into MDCK cells stably transfected with eGFP-tagged nectin 2, one of the adhesion molecules known to be expressed in Sertoli cells at adhesion junctions. Cells transfected with the dynamin 3 construct had less uniformly distributed nectin 2 at intercellular contacts when compared to control cells expressing only nectin 2 or transfected with the DsRed plasmid alone. Significantly, tubular extensions positive for nectin 2 were visible projecting into the cells from regions of intercellular contact. Our findings are consistent with the conclusion that dynamin 3 is involved with tubulobulbar morphogenesis. Dynamin 3 also occurs in concentrated deposits around the capitulum and striated columns in the connecting piece of sperm tails suggesting that the protein in these cells may function to stabilize the base of the tail or serve as a reservoir for use during or after fertilization.
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Affiliation(s)
- K S Vaid
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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40
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Abstract
Cortactin, an actin filament-binding protein and target of multiple kinases, has emerged as a central element connecting signaling pathways with cytoskeleton restructuring. It is involved in a perplexingly diverse array of cellular processes, including cell motility, invasiveness, synaptogenesis, endocytosis, intercellular contact assembly, and host-pathogen interactions, where the common denominator appears to be a role in the coordination of membrane dynamics with cytoskeletal remodeling. Although in recent years our knowledge about cortactin has increased exponentially, the exact mechanisms underlying its fundamental roles remain to be defined.
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Affiliation(s)
- Laura I Cosen-Binker
- Saint Michael's Hospital Research Institute, Department of Surgery, University of Toronto, Ontario, Canada
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41
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Meckler X, Bertandeau E, McNiven MA, Allinquant B, Hémar A. The cytosolic domain of APP induces the relocalization of dynamin 3 in hippocampal neurons. Eur J Neurosci 2006; 24:2439-43. [PMID: 17100832 DOI: 10.1111/j.1460-9568.2006.05141.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amyloid precursor protein (APP) has been the subject of intense research to uncover its implication in Alzheimer's disease. Its physiological function is, however, still poorly understood. Herein, we investigated its possible influence on the development of cultured hippocampal neurons. A peptide corresponding to the APP intracellular domain linked to a cell-penetrating peptide was used to alter the interactions of APP with its cytosolic partners. This treatment promoted the concentration of the cytosolic GTPase dynamin 3 (Dyn3) in neurite segments when most untreated cells displayed a homogenous punctate distribution of Dyn3. The Dyn3-labelled segments were excluded from those revealed by APP staining after aldehyde fixation. Interestingly, after aldehyde fixation MAP2 also labelled segments excluded from APP-stained segments. Thus APP is also a marker for the spacing pattern of neurites demonstrated by Taylor & Fallon (2006)J. Neurosci., 26, 1154-4463.
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Affiliation(s)
- X Meckler
- Physiologie Cellulaire de la Synapse, UMR5091 CNRS, Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33077 Bordeaux Cedex, France
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42
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Abstract
Neurons are among the largest and most complex cells in the body. Their immense size and intricate geometry pose many unique cell-biological problems. How is dendritic architecture established and maintained? How do neurons traffic newly synthesized integral membrane proteins over such long distances to synapses? Functionally, protein trafficking to and from the postsynaptic membrane has emerged as a key mechanism underlying various forms of synaptic plasticity. Which organelles are involved in postsynaptic trafficking, and how do they integrate and respond to activity at individual synapses? Here we review what is currently known about long-range trafficking of newly synthesized postsynaptic proteins as well as the local rules that govern postsynaptic trafficking at individual synapses.
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Affiliation(s)
- Matthew J Kennedy
- Howard Hughes Medical Institute, Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
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43
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Elia LP, Yamamoto M, Zang K, Reichardt LF. p120 catenin regulates dendritic spine and synapse development through Rho-family GTPases and cadherins. Neuron 2006; 51:43-56. [PMID: 16815331 PMCID: PMC2587166 DOI: 10.1016/j.neuron.2006.05.018] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2005] [Revised: 02/17/2006] [Accepted: 05/23/2006] [Indexed: 11/20/2022]
Abstract
Both the cadherin-catenin complex and Rho-family GTPases have been shown to regulate dendrite development. We show here a role for p120 catenin (p120ctn) in regulating spine and synapse formation in the developing mouse brain. p120catenin gene deletion in hippocampal pyramidal neurons in vivo resulted in reduced spine and synapse densities along dendrites. In addition, p120 catenin loss resulted in reduced cadherin levels and misregulation of Rho-family GTPases, with decreased Rac1 and increased RhoA activity. Analyses in vitro indicate that the reduced spine density reflects aberrant Rho-family GTPase signaling, whereas the effects on spine maturation appear to result from reduced cadherin levels and possibly aberrant Rho-family GTPase signaling. Thus, p120ctn acts as a signal coordinator between cadherins and Rho-family GTPases to regulate cytoskeletal changes required during spine and synapse development.
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Affiliation(s)
- Lisa P Elia
- Howard Hughes Medical Institute and Department of Physiology, 1550 Fourth Street, University of California, San Francisco, San Francisco, California 94143, USA
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44
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Soulet F, Schmid SL, Damke H. Domain requirements for an endocytosis-independent, isoform-specific function of dynamin-2. Exp Cell Res 2006; 312:3539-45. [PMID: 16938290 DOI: 10.1016/j.yexcr.2006.07.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Accepted: 07/27/2006] [Indexed: 11/20/2022]
Abstract
Endocytosis is inhibited by overexpression of either dynamin-1 or dynamin-2 mutants because both isoforms form heterotetramers with endogenous dynamin-2 and interfere with its function. By contrast, other phenotypes, which are specifically triggered by overexpression of dynamin-2, but not dynamin-1 are likely to reflect endocytosis-independent, dynamin-2-specific functions and/or interactions. Using Dyn2/Dyn1 chimeras, we explored the structural requirements for a readily quantifiable, isoform-specific function of dynamin-2, the activation of caspase-3 to trigger apoptosis. Strikingly, swapping the highly homologous GTPase domain of dynamin-2 into dynamin-1 was sufficient to confer caspase-3 activation. Moreover, assembly-defective mutations in GED, dynamin's GAP/assembly domain, that inhibit endocytosis enhance caspase-3 activation. Thus, this dynamin-2-specific function is mechanistically distinct from and independent of its role in endocytosis. These findings have important implications for interpreting dynamin-2 dependent phenotypes in overexpression studies.
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Affiliation(s)
- Fabienne Soulet
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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45
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Tada T, Sheng M. Molecular mechanisms of dendritic spine morphogenesis. Curr Opin Neurobiol 2006; 16:95-101. [PMID: 16361095 DOI: 10.1016/j.conb.2005.12.001] [Citation(s) in RCA: 512] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2005] [Accepted: 12/02/2005] [Indexed: 11/29/2022]
Abstract
Excitatory synapses are formed on dendritic spines, postsynaptic structures that change during development and in response to synaptic activity. Once mature, however, spines can remain stable for many months. The molecular mechanisms that control the formation and elimination, motility and stability, and size and shape of dendritic spines are being revealed. Multiple signaling pathways, particularly those involving Rho and Ras family small GTPases, converge on the actin cytoskeleton to regulate spine morphology and dynamics bidirectionally. Numerous cell surface receptors, scaffold proteins and actin binding proteins are concentrated in spines and engaged in spine morphogenesis.
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Affiliation(s)
- Tomoko Tada
- The Picower Institute for Learning and Memory, RIKEN-MIT Neuroscience Research Center, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
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46
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Illés A, Enyedi B, Tamás P, Balázs A, Bogel G, Buday L. Cortactin is required for integrin-mediated cell spreading. Immunol Lett 2005; 104:124-30. [PMID: 16364453 DOI: 10.1016/j.imlet.2005.11.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 11/03/2005] [Accepted: 11/08/2005] [Indexed: 12/28/2022]
Abstract
Cortactin is an SH3 domain-containing protein that contributes to the formation of dynamic cortical actin-associated structures, such as lamellipodia and membrane ruffles. Here we show that expression of either the GFP-tagged N-terminal or the C-teminal halves of cortactin inhibits significantly the spreading of COS7 cells on fibronectin. Introducing inactivating point mutation into the SH3 domain of the C-terminal half of cortactin suspends the dominant negative effect of the construct. In addition, a vector-based RNA interference was used to knock-down endogenous level of cortactin in cells. We demonstrate that cortactin deficient cells were not able to spread. These results suggest that cortactin is required for integrin-mediated signalling pathways.
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Affiliation(s)
- András Illés
- Department of Medical Chemistry, Semmelweis University Medical School, 9 Puskin Street, 1088 Budapest, Hungary
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47
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Abstract
The dendritic nucleation model was devised to explain the cycle of actin dynamics resulting in actin filament network assembly and disassembly in two contexts--at the leading edge of motile cells and in the actin comet tails of intracellular pathogenic bacteria and viruses. Due to the detailed nature of its biochemical predictions, the model has provided an excellent focus for subsequent experimentation. This review summarizes recent work on actin dynamics in the context of the dendritic nucleation model. One outcome of this research is the possibility that additional proteins, as well as the six proteins included in the original model, might increase the efficiency of dendritic nucleation or modify the resulting actin network. In addition, actin dynamics at the leading edge might be influenced by a second actin filament network, independent of dendritic nucleation.
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48
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Yao Q, Chen J, Cao H, Orth JD, McCaffery JM, Stan RV, McNiven MA. Caveolin-1 Interacts Directly with Dynamin-2. J Mol Biol 2005; 348:491-501. [PMID: 15811383 DOI: 10.1016/j.jmb.2005.02.003] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2004] [Revised: 02/01/2005] [Accepted: 02/02/2005] [Indexed: 11/20/2022]
Abstract
Caveolin is the principal component of caveolae in vivo. In addition to a structural role, it is believed to play a scaffolding function to organize and inactivate signaling molecules that are concentrated on the cytoplasmic surface of caveolar membranes. The large GTPase dynamin has been shown to mediate the scission of caveolae from the plasma membrane, although it is unclear if dynamin interacts directly with caveolin or via accessory proteins. Therefore, the goal of this study was to test whether dynamin associates with caveolae via a direct binding to the caveolin 1 (Cav1) protein. Immunoelectron microscopy of lung endothelium or a cultured hepatocyte cell line stained with antibodies for Dyn2 and Cav1 shows that these proteins co-localize to caveolae. To further define this interaction biochemically, in vitro experiments were performed using glutathione-S-transferase (GST)-Dyn2 and GST-Cav1 fusion proteins, which demonstrated a direct interaction between these proteins. This interaction appears to be mediated by the proline-arginine-rich domain (PRD) of Dyn2, as a GST-PRD fragment binds Cav1 while GST-Dyn2DeltaPRD does not. Further, in vitro binding studies using two Dyn2 spliced forms and Cav1 peptides immobilized on paper identify specific domains of Cav1 that bind Dyn2. Interestingly, these Cav1-binding domains differ markedly between two spliced variant forms of Dyn2. In support of these distinctive physical interactions, we find that the different Dyn2 forms, when expressed as GTPase-defective mutants, exert markedly different inhibitory effects on caveolae internalization, as assayed by cholera toxin uptake. These studies provide the first evidence for a direct interaction between dynamin and the caveolin coat, and demonstrate a selectivity of one Dyn2 form toward the caveolae-mediated endocytosis.
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Affiliation(s)
- Qing Yao
- Center for Basic Research in Digestive Diseases, and Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
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