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Bayonés L, Guerra-Fernández MJ, Figueroa-Cares C, Gallo LI, Alfonso-Bueno S, Caspe O, Canal MP, Báez-Matus X, González-Jamett A, Cárdenas AM, Marengo FD. Dynamin-2 mutations linked to neonatal-onset centronuclear myopathy impair exocytosis and endocytosis in adrenal chromaffin cells. J Neurochem 2024. [PMID: 39126680 DOI: 10.1111/jnc.16194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 06/28/2024] [Accepted: 07/17/2024] [Indexed: 08/12/2024]
Abstract
Dynamins are large GTPases whose primary function is not only to catalyze membrane scission during endocytosis but also to modulate other cellular processes, such as actin polymerization and vesicle trafficking. Recently, we reported that centronuclear myopathy associated dynamin-2 mutations, p.A618T, and p.S619L, impair Ca2+-induced exocytosis of the glucose transporter GLUT4 containing vesicles in immortalized human myoblasts. As exocytosis and endocytosis occur within rapid timescales, here we applied high-temporal resolution techniques, such as patch-clamp capacitance measurements and carbon-fiber amperometry to assess the effects of these mutations on these two cellular processes, using bovine chromaffin cells as a study model. We found that the expression of any of these dynamin-2 mutants inhibits a dynamin and F-actin-dependent form of fast endocytosis triggered by single action potential stimulus, as well as inhibits a slow compensatory endocytosis induced by 500 ms square depolarization. Both dynamin-2 mutants further reduced the exocytosis induced by 500 ms depolarizations, and the frequency of release events and the recruitment of neuropeptide Y (NPY)-labeled vesicles to the cell cortex after stimulation of nicotinic acetylcholine receptors with 1,1-dimethyl-4-phenyl piperazine iodide (DMPP). They also provoked a significant decrease in the Ca2+-induced formation of new actin filaments in permeabilized chromaffin cells. In summary, our results indicate that the centronuclear myopathy (CNM)-linked p.A618T and p.S619L mutations in dynamin-2 affect exocytosis and endocytosis, being the disruption of F-actin dynamics a possible explanation for these results. These impaired cellular processes might underlie the pathogenic mechanisms associated with these mutations.
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Affiliation(s)
- Lucas Bayonés
- Instituto de Fisiología, Biología Molecular y Neurociencias. CONICET. Departamento de Fisiología y Biología Molecular y Celular. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires, Buenos Aires, Argentina
| | - María José Guerra-Fernández
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Cindel Figueroa-Cares
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Luciana I Gallo
- Instituto de Fisiología, Biología Molecular y Neurociencias. CONICET. Departamento de Fisiología y Biología Molecular y Celular. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Samuel Alfonso-Bueno
- Instituto de Fisiología, Biología Molecular y Neurociencias. CONICET. Departamento de Fisiología y Biología Molecular y Celular. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Octavio Caspe
- Instituto de Fisiología, Biología Molecular y Neurociencias. CONICET. Departamento de Fisiología y Biología Molecular y Celular. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires, Buenos Aires, Argentina
| | - María Pilar Canal
- Instituto de Fisiología, Biología Molecular y Neurociencias. CONICET. Departamento de Fisiología y Biología Molecular y Celular. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Ximena Báez-Matus
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Arlek González-Jamett
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
- Escuela de Química y Farmacia, Facultad de Farmacia, Universidad de Valparaíso, Valparaíso, Chile
- Centro para la Investigación Traslacional en Neurofarmacología, CitNe, Universidad de Valparaíso, Valparaiso, Chile
| | - Ana M Cárdenas
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Fernando D Marengo
- Instituto de Fisiología, Biología Molecular y Neurociencias. CONICET. Departamento de Fisiología y Biología Molecular y Celular. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires, Buenos Aires, Argentina
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2
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Wei L, Guo X, Haimov E, Obashi K, Lee SH, Shin W, Sun M, Chan CY, Sheng J, Zhang Z, Mohseni A, Ghosh Dastidar S, Wu XS, Wang X, Han S, Arpino G, Shi B, Molakarimi M, Matthias J, Wurm CA, Gan L, Taraska JW, Kozlov MM, Wu LG. Clathrin mediates membrane fission and budding by constricting membrane pores. Cell Discov 2024; 10:62. [PMID: 38862506 PMCID: PMC11166961 DOI: 10.1038/s41421-024-00677-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 04/04/2024] [Indexed: 06/13/2024] Open
Abstract
Membrane budding, which underlies fundamental processes like endocytosis, intracellular trafficking, and viral infection, is thought to involve membrane coat-forming proteins, including the most observed clathrin, to form Ω-shape profiles and helix-forming proteins like dynamin to constrict Ω-profiles' pores and thus mediate fission. Challenging this fundamental concept, we report that polymerized clathrin is required for Ω-profiles' pore closure and that clathrin around Ω-profiles' base/pore region mediates pore constriction/closure in neuroendocrine chromaffin cells. Mathematical modeling suggests that clathrin polymerization at Ω-profiles' base/pore region generates forces from its intrinsically curved shape to constrict/close the pore. This new fission function may exert broader impacts than clathrin's well-known coat-forming function during clathrin (coat)-dependent endocytosis, because it underlies not only clathrin (coat)-dependent endocytosis, but also diverse endocytic modes, including ultrafast, fast, slow, bulk, and overshoot endocytosis previously considered clathrin (coat)-independent in chromaffin cells. It mediates kiss-and-run fusion (fusion pore closure) previously considered bona fide clathrin-independent, and limits the vesicular content release rate. Furthermore, analogous to results in chromaffin cells, we found that clathrin is essential for fast and slow endocytosis at hippocampal synapses where clathrin was previously considered dispensable, suggesting clathrin in mediating synaptic vesicle endocytosis and fission. These results suggest that clathrin and likely other intrinsically curved coat proteins are a new class of fission proteins underlying vesicle budding and fusion. The half-a-century concept and studies that attribute vesicle-coat contents' function to Ω-profile formation and classify budding as coat-protein (e.g., clathrin)-dependent or -independent may need to be re-defined and re-examined by considering clathrin's pivotal role in pore constriction/closure.
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Affiliation(s)
- Lisi Wei
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Xiaoli Guo
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Ehud Haimov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel
| | - Kazuki Obashi
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD, USA
| | - Sung Hoon Lee
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
- Chung-Ang University, Seoul, Republic of Korea
| | - Wonchul Shin
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Min Sun
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Chung Yu Chan
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Jiansong Sheng
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
- 900 Clopper Rd, Suite, 130, Gaithersburg, MD, USA
| | - Zhen Zhang
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
- Center of Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Ammar Mohseni
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | | | - Xin-Sheng Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Xin Wang
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Sue Han
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Gianvito Arpino
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
- Emme 3 Srl - Via Luigi Meraviglia, 31 - 20020, Lainate, MI, Italy
| | - Bo Shi
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Maryam Molakarimi
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | | | | | - Lin Gan
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - Justin W Taraska
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD, USA
| | - Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel.
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
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Shin W, Zucker B, Kundu N, Lee SH, Shi B, Chan CY, Guo X, Harrison JT, Turechek JM, Hinshaw JE, Kozlov MM, Wu LG. Molecular mechanics underlying flat-to-round membrane budding in live secretory cells. Nat Commun 2022; 13:3697. [PMID: 35760780 PMCID: PMC9237132 DOI: 10.1038/s41467-022-31286-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 06/10/2022] [Indexed: 12/21/2022] Open
Abstract
Membrane budding entails forces to transform flat membrane into vesicles essential for cell survival. Accumulated studies have identified coat-proteins (e.g., clathrin) as potential budding factors. However, forces mediating many non-coated membrane buddings remain unclear. By visualizing proteins in mediating endocytic budding in live neuroendocrine cells, performing in vitro protein reconstitution and physical modeling, we discovered how non-coated-membrane budding is mediated: actin filaments and dynamin generate a pulling force transforming flat membrane into Λ-shape; subsequently, dynamin helices surround and constrict Λ-profile's base, transforming Λ- to Ω-profile, and then constrict Ω-profile's pore, converting Ω-profiles to vesicles. These mechanisms control budding speed, vesicle size and number, generating diverse endocytic modes differing in these parameters. Their impact is widespread beyond secretory cells, as the unexpectedly powerful functions of dynamin and actin, previously thought to mediate fission and overcome tension, respectively, may contribute to many dynamin/actin-dependent non-coated-membrane buddings, coated-membrane buddings, and other membrane remodeling processes.
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Affiliation(s)
- Wonchul Shin
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Ben Zucker
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978, Ramat Aviv, Israel
| | - Nidhi Kundu
- Structural Cell Biology Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Sung Hoon Lee
- Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Bo Shi
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Chung Yu Chan
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Xiaoli Guo
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Jonathan T Harrison
- Structural Cell Biology Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | | | - Jenny E Hinshaw
- Structural Cell Biology Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA.
| | - Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978, Ramat Aviv, Israel.
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
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Gustafsson JK, Davis JE, Rappai T, McDonald KG, Kulkarni DH, Knoop KA, Hogan SP, Fitzpatrick JAJ, Lencer WI, Newberry RD. Intestinal goblet cells sample and deliver lumenal antigens by regulated endocytic uptake and transcytosis. eLife 2021; 10:e67292. [PMID: 34677124 PMCID: PMC8594945 DOI: 10.7554/elife.67292] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 10/20/2021] [Indexed: 12/12/2022] Open
Abstract
Intestinal goblet cells maintain the protective epithelial barrier through mucus secretion and yet sample lumenal substances for immune processing through formation of goblet cell associated antigen passages (GAPs). The cellular biology of GAPs and how these divergent processes are balanced and regulated by goblet cells remains unknown. Using high-resolution light and electron microscopy, we found that in mice, GAPs were formed by an acetylcholine (ACh)-dependent endocytic event remarkable for delivery of fluid-phase cargo retrograde into the trans-golgi network and across the cell by transcytosis - in addition to the expected transport of fluid-phase cargo by endosomes to multi-vesicular bodies and lysosomes. While ACh also induced goblet cells to secrete mucins, ACh-induced GAP formation and mucin secretion were functionally independent and mediated by different receptors and signaling pathways, enabling goblet cells to differentially regulate these processes to accommodate the dynamically changing demands of the mucosal environment for barrier maintenance and sampling of lumenal substances.
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Affiliation(s)
- Jenny K Gustafsson
- Department of Neuroscience and Physiology, University of GothenburgGothenburgSweden
- Department of Internal Medicine, Washington University School of MedicineSt LouisUnited States
| | - Jazmyne E Davis
- Department of Internal Medicine, Washington University School of MedicineSt LouisUnited States
| | - Tracy Rappai
- Center for Cellular Imaging, Washington University School of MedicineSt LouisUnited States
| | - Keely G McDonald
- Department of Internal Medicine, Washington University School of MedicineSt LouisUnited States
| | - Devesha H Kulkarni
- Department of Internal Medicine, Washington University School of MedicineSt LouisUnited States
| | - Kathryn A Knoop
- Department of Internal Medicine, Washington University School of MedicineSt LouisUnited States
| | - Simon P Hogan
- Mary H. Weiser Food Allergy Center, University of Michigan School of Medicine,Ann ArborUnited States
| | - James AJ Fitzpatrick
- Center for Cellular Imaging, Washington University School of MedicineSt LouisUnited States
- Department of Cell Biology &Physiology, Washington University School of MedicineSt LouisUnited States
- Department of Neuroscience, Washington University School of MedicineSt LouisUnited States
- Department of Biomedical Engineering, Washington University in St. LouisSt. LouisUnited States
| | - Wayne I Lencer
- Department of Pediatrics, Harvard Medical SchoolBostonUnited States
- Division of Gastroenterology, Nutrition and Hepatology, Boston Children’s HospitalBostonUnited States
- Harvard Digestive Disease Center, Harvard Medical SchoolBostonUnited States
| | - Rodney D Newberry
- Department of Internal Medicine, Washington University School of MedicineSt LouisUnited States
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Preformed Ω-profile closure and kiss-and-run mediate endocytosis and diverse endocytic modes in neuroendocrine chromaffin cells. Neuron 2021; 109:3119-3134.e5. [PMID: 34411513 DOI: 10.1016/j.neuron.2021.07.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 06/02/2021] [Accepted: 07/23/2021] [Indexed: 01/29/2023]
Abstract
Transformation of flat membrane into round vesicles is generally thought to underlie endocytosis and produce speed-, amount-, and vesicle-size-specific endocytic modes. Visualizing depolarization-induced exocytic and endocytic membrane transformation in live neuroendocrine chromaffin cells, we found that flat membrane is transformed into Λ-shaped, Ω-shaped, and O-shaped vesicles via invagination, Λ-base constriction, and Ω-pore constriction, respectively. Surprisingly, endocytic vesicle formation is predominantly from not flat-membrane-to-round-vesicle transformation but calcium-triggered and dynamin-mediated closure of (1) Ω profiles formed before depolarization and (2) fusion pores (called kiss-and-run). Varying calcium influxes control the speed, number, and vesicle size of these pore closures, resulting in speed-specific slow (more than ∼6 s), fast (less than ∼6 s), or ultrafast (<0.6 s) endocytosis, amount-specific compensatory endocytosis (endocytosis = exocytosis) or overshoot endocytosis (endocytosis > exocytosis), and size-specific bulk endocytosis. These findings reveal major membrane transformation mechanisms underlying endocytosis, diverse endocytic modes, and exocytosis-endocytosis coupling, calling for correction of the half-a-century concept that the flat-to-round transformation predominantly mediates endocytosis after physiological stimulation.
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Miklavc P, Frick M. Actin and Myosin in Non-Neuronal Exocytosis. Cells 2020; 9:cells9061455. [PMID: 32545391 PMCID: PMC7348895 DOI: 10.3390/cells9061455] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/03/2020] [Accepted: 06/06/2020] [Indexed: 12/18/2022] Open
Abstract
Cellular secretion depends on exocytosis of secretory vesicles and discharge of vesicle contents. Actin and myosin are essential for pre-fusion and post-fusion stages of exocytosis. Secretory vesicles depend on actin for transport to and attachment at the cell cortex during the pre-fusion phase. Actin coats on fused vesicles contribute to stabilization of large vesicles, active vesicle contraction and/or retrieval of excess membrane during the post-fusion phase. Myosin molecular motors complement the role of actin. Myosin V is required for vesicle trafficking and attachment to cortical actin. Myosin I and II members engage in local remodeling of cortical actin to allow vesicles to get access to the plasma membrane for membrane fusion. Myosins stabilize open fusion pores and contribute to anchoring and contraction of actin coats to facilitate vesicle content release. Actin and myosin function in secretion is regulated by a plethora of interacting regulatory lipids and proteins. Some of these processes have been first described in non-neuronal cells and reflect adaptations to exocytosis of large secretory vesicles and/or secretion of bulky vesicle cargoes. Here we collate the current knowledge and highlight the role of actomyosin during distinct phases of exocytosis in an attempt to identify unifying molecular mechanisms in non-neuronal secretory cells.
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Affiliation(s)
- Pika Miklavc
- School of Science, Engineering & Environment, University of Salford, Manchester M5 4WT, UK
- Correspondence: (P.M.); (M.F.); Tel.: +44-0161-295-3395 (P.M.); +49-731-500-23115 (M.F.); Fax: +49-731-500-23242 (M.F.)
| | - Manfred Frick
- Institute of General Physiology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
- Correspondence: (P.M.); (M.F.); Tel.: +44-0161-295-3395 (P.M.); +49-731-500-23115 (M.F.); Fax: +49-731-500-23242 (M.F.)
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7
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Yang L, Fomina AF. Ca 2+ influx and clearance at hyperpolarized membrane potentials modulate spontaneous and stimulated exocytosis in neuroendocrine cells. Cell Calcium 2020; 87:102184. [PMID: 32151786 DOI: 10.1016/j.ceca.2020.102184] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 02/10/2020] [Accepted: 02/21/2020] [Indexed: 01/09/2023]
Abstract
Neuroendocrine adrenal chromaffin cells release neurohormones catecholamines in response to Ca2+ entry via voltage-gated Ca2+ channels (VGCCs). Adrenal chromaffin cells also express non-voltage-gated channels, which may conduct Ca2+ at negative membrane potentials, whose role in regulation of exocytosis is poorly understood. We explored how modulation of Ca2+ influx at negative membrane potentials affects basal cytosolic Ca2+ concentration ([Ca2+]i) and exocytosis in metabolically intact voltage-clamped bovine adrenal chromaffin cells. We found that in these cells, Ca2+ entry at negative membrane potentials is balanced by Ca2+ extrusion by the Na+/Ca2+ exchanger and that this balance can be altered by membrane hyperpolarization or stimulation with an inflammatory hormone bradykinin. Membrane hyperpolarization or application of bradykinin augmented Ca2+-carrying current at negative membrane potentials, elevated basal [Ca2+]i, and facilitated synchronous exocytosis evoked by the small amounts of Ca2+ injected into the cell via VGCCs (up to 20 pC). Exocytotic responses evoked by the injections of the larger amounts of Ca2+ via VGCCs (> 20 pC) were suppressed by preceding hyperpolarization. In the absence of Ca2+ entry via VGCCs and Ca2+ extrusion via the Na+/Ca2+ exchanger, membrane hyperpolarization induced a significant elevation in [Ca2+]i and asynchronous exocytosis. Our results indicate that physiological interferences, such as membrane hyperpolarization and/or activation of non-voltage-gated Ca2+ channels, modulate basal [Ca2+]i and, consequently, segregation of exocytotic vesicles and their readiness to be released spontaneously and in response to Ca2+ entry via VGCCs. These mechanisms may play role in homeostatic plasticity of neuronal and endocrine cells.
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Affiliation(s)
- Lukun Yang
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, 95616, USA; Department of Anesthesiology, The 5th Affiliated Hospital of SUN YAT-SEN University, Zhuhai, 519000, China.
| | - Alla F Fomina
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, 95616, USA.
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Shin W, Arpino G, Thiyagarajan S, Su R, Ge L, McDargh Z, Guo X, Wei L, Shupliakov O, Jin A, O'Shaughnessy B, Wu LG. Vesicle Shrinking and Enlargement Play Opposing Roles in the Release of Exocytotic Contents. Cell Rep 2020; 30:421-431.e7. [PMID: 31940486 PMCID: PMC7010319 DOI: 10.1016/j.celrep.2019.12.044] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 11/15/2019] [Accepted: 12/12/2019] [Indexed: 12/13/2022] Open
Abstract
For decades, two fusion modes were thought to control hormone and transmitter release essential to life; one facilitates release via fusion pore dilation and flattening (full collapse), and the other limits release by closing a narrow fusion pore (kiss-and-run). Using super-resolution stimulated emission depletion (STED) microscopy to visualize fusion modes of dense-core vesicles in neuroendocrine cells, we find that facilitation of release is mediated not by full collapse but by shrink fusion, in which the Ω-profile generated by vesicle fusion shrinks but maintains a large non-dilating pore. We discover that the physiological osmotic pressure of a cell squeezes, but does not dilate, the Ω-profile, which explains why shrink fusion prevails over full collapse. Instead of kiss-and-run, enlarge fusion, in which Ω-profiles grow while maintaining a narrow pore, slows down release. Shrink and enlarge fusion may thus account for diverse hormone and transmitter release kinetics observed in secretory cells, previously interpreted within the full-collapse/kiss-and-run framework.
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Affiliation(s)
- Wonchul Shin
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Gianvito Arpino
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA; Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Sathish Thiyagarajan
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA
| | - Rui Su
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA
| | - Lihao Ge
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Zachary McDargh
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA
| | - Xiaoli Guo
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Lisi Wei
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden; Institute of Translational Biomedicine, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Albert Jin
- National Institute of Biomedical Imaging and Bioengineering (NIBIB), Bethesda, MD 20892, USA
| | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA.
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA.
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Gómez-Elías MD, Fissore RA, Cuasnicú PS, Cohen DJ. Compensatory endocytosis occurs after cortical granule exocytosis in mouse eggs. J Cell Physiol 2019; 235:4351-4360. [PMID: 31612508 DOI: 10.1002/jcp.29311] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 09/30/2019] [Indexed: 12/31/2022]
Abstract
Compensatory endocytosis (CE) is one of the primary mechanisms through which cells maintain their surface area after exocytosis. Considering that in eggs massive exocytosis of cortical granules (CG) takes place after fertilization, the aim of this study was to evaluate the occurrence of CE following cortical exocytosis in mouse eggs. For this purpose, we developed a pulse-chase assay to detect CG membrane internalization. Results showed internalized labeling in SrCl2 -activated and fertilized eggs when chasing at 37°C, but not at a nonpermissive temperature (4°C). The use of kinase and calcineurin inhibitors led us to conclude that this internal labeling corresponded to CE. Further experiments showed that CE in mouse eggs is dependent on actin dynamics and dynamin activity, and could be associated with a transient exposure of phosphatidylserine. Finally, CE was impaired in A23187 ionophore-activated eggs, highlighting once again the mechanistic differences between the activation methods. Altogether, these results demonstrate for the first time that egg activation triggers CE in mouse eggs after exocytosis of CG, probably as a plasma membrane homeostasis mechanism.
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Affiliation(s)
- Matías D Gómez-Elías
- Laboratorio de Mecanismos Moleculares de la Fertilización, Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científico y Técnicas (IBYME-CONICET), Buenos Aires, Argentina
| | - Rafael A Fissore
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, 661 North Pleasant Street, Amherst, Massachusetts
| | - Patricia S Cuasnicú
- Laboratorio de Mecanismos Moleculares de la Fertilización, Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científico y Técnicas (IBYME-CONICET), Buenos Aires, Argentina
| | - Débora J Cohen
- Laboratorio de Mecanismos Moleculares de la Fertilización, Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científico y Técnicas (IBYME-CONICET), Buenos Aires, Argentina
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10
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Carbone E, Borges R, Eiden LE, García AG, Hernández‐Cruz A. Chromaffin Cells of the Adrenal Medulla: Physiology, Pharmacology, and Disease. Compr Physiol 2019; 9:1443-1502. [DOI: 10.1002/cphy.c190003] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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11
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Tse A, Lee AK, Takahashi N, Gong A, Kasai H, Tse FW. Strong stimulation triggers full fusion exocytosis and very slow endocytosis of the small dense core granules in carotid glomus cells. J Neurogenet 2018; 32:267-278. [PMID: 30484390 DOI: 10.1080/01677063.2018.1497629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Chemosensory glomus cells of the carotid bodies release transmitters, including ATP and dopamine mainly via the exocytosis of small dense core granules (SDCGs, vesicular diameter of ∼100 nm). Using carbon-fiber amperometry, we showed previously that with a modest uniform elevation in cytosolic Ca2+ concentration ([Ca2+]i of ∼0.5 µM), SDCGs of rat glomus cells predominantly underwent a "kiss-and-run" mode of exocytosis. Here, we examined whether a larger [Ca2+]i rise influenced the mode of exocytosis. Activation of voltage-gated Ca2+ channels by a train of voltage-clamped depolarizations which elevated [Ca2+]i to ∼1.6 μM increased the cell membrane capacitance by ∼2.5%. At 30 s after such a stimulus, only 5% of the added membrane was retrieved. Flash photolysis of caged-Ca2+ (which elevated [Ca2+]i to ∼16 μM) increased cell membrane capacitance by ∼13%, and only ∼30% of the added membrane was retrieved at 30 s after the UV flash. When exocytosis and endocytosis were monitored using the two-photon excitation and extracellular polar tracer (TEP) imaging of FM1-43 fluorescence in conjunction with photolysis of caged Ca2+, almost uniform exocytosis was detected over the cell's entire surface and it was followed by slow endocytosis. Immunocytochemistry showed that the cytoplasmic densities of dynamin I, II and clathrin (key proteins that mediate endocytosis) in glomus cells were less than half of those in adrenal chromaffin cells, suggesting that a lower expression of endocytotic machinery may underlie the slow endocytosis in glomus cells. An analysis of the relative change in the signals from two fluorescent dyes that simultaneously monitored the addition of vesicular volume and plasma membrane surface area, suggested that with an intense stimulus, SDCGs of glomus cells underwent full fusion without any significant "compound" exocytosis. Therefore, during a severe hypoxic challenge, glomus granules undergo full fusion for a more complete release of transmitters.
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Affiliation(s)
- Amy Tse
- a Department of Pharmacology and Neuroscience and Metal Health Institute , University of Alberta , Edmonton , Canada
| | - Andy K Lee
- a Department of Pharmacology and Neuroscience and Metal Health Institute , University of Alberta , Edmonton , Canada
| | - Noriko Takahashi
- b Department of Physiology , Kitasato University School of Medicine , Sagamihara , Japan
| | - Alex Gong
- a Department of Pharmacology and Neuroscience and Metal Health Institute , University of Alberta , Edmonton , Canada
| | - Haruo Kasai
- c Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine , The University of Tokyo , Bunkyo-ku , Japan.,d International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo , Bunkyo-ku , Japan
| | - Frederick W Tse
- a Department of Pharmacology and Neuroscience and Metal Health Institute , University of Alberta , Edmonton , Canada
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12
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Shin W, Ge L, Arpino G, Villarreal SA, Hamid E, Liu H, Zhao WD, Wen PJ, Chiang HC, Wu LG. Visualization of Membrane Pore in Live Cells Reveals a Dynamic-Pore Theory Governing Fusion and Endocytosis. Cell 2018; 173:934-945.e12. [PMID: 29606354 PMCID: PMC5935532 DOI: 10.1016/j.cell.2018.02.062] [Citation(s) in RCA: 136] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 02/22/2018] [Accepted: 02/27/2018] [Indexed: 01/03/2023]
Abstract
Fusion is thought to open a pore to release vesicular cargoes vital for many biological processes, including exocytosis, intracellular trafficking, fertilization, and viral entry. However, fusion pores have not been observed and thus proved in live cells. Its regulatory mechanisms and functions remain poorly understood. With super-resolution STED microscopy, we observed dynamic fusion pore behaviors in live (neuroendocrine) cells, including opening, expansion, constriction, and closure, where pore size may vary between 0 and 490 nm within 26 milliseconds to seconds (vesicle size: 180-720 nm). These pore dynamics crucially determine the efficiency of vesicular cargo release and vesicle retrieval. They are generated by competition between pore expansion and constriction. Pharmacology and mutation experiments suggest that expansion and constriction are mediated by F-actin-dependent membrane tension and calcium/dynamin, respectively. These findings provide the missing live-cell evidence, proving the fusion-pore hypothesis, and establish a live-cell dynamic-pore theory accounting for fusion, fission, and their regulation.
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Affiliation(s)
- Wonchul Shin
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Lihao Ge
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Gianvito Arpino
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Seth A Villarreal
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Edaeni Hamid
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Huisheng Liu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Wei-Dong Zhao
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Peter J Wen
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Hsueh-Cheng Chiang
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
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13
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Hilgemann DW, Dai G, Collins A, Lariccia V, Magi S, Deisl C, Fine M. Lipid signaling to membrane proteins: From second messengers to membrane domains and adapter-free endocytosis. J Gen Physiol 2018; 150:211-224. [PMID: 29326133 PMCID: PMC5806671 DOI: 10.1085/jgp.201711875] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Hilgemann et al. explain how lipid signaling to membrane proteins involves a hierarchy of mechanisms from lipid binding to membrane domain coalescence. Lipids influence powerfully the function of ion channels and transporters in two well-documented ways. A few lipids act as bona fide second messengers by binding to specific sites that control channel and transporter gating. Other lipids act nonspecifically by modifying the physical environment of channels and transporters, in particular the protein–membrane interface. In this short review, we first consider lipid signaling from this traditional viewpoint, highlighting innumerable Journal of General Physiology publications that have contributed to our present understanding. We then switch to our own emerging view that much important lipid signaling occurs via the formation of membrane domains that influence the function of channels and transporters within them, promote selected protein–protein interactions, and control the turnover of surface membrane.
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Affiliation(s)
- Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Gucan Dai
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Anthony Collins
- Saba University School of Medicine, The Bottom, Saba, Dutch Caribbean
| | - Vincenzo Lariccia
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche," Ancona, Italy
| | - Simona Magi
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche," Ancona, Italy
| | - Christine Deisl
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Michael Fine
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX
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14
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Brännmark C, Lövfors W, Komai AM, Axelsson T, El Hachmane MF, Musovic S, Paul A, Nyman E, Olofsson CS. Mathematical modeling of white adipocyte exocytosis predicts adiponectin secretion and quantifies the rates of vesicle exo- and endocytosis. J Biol Chem 2017; 292:20032-20043. [PMID: 28972187 DOI: 10.1074/jbc.m117.801225] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/22/2017] [Indexed: 11/06/2022] Open
Abstract
Adiponectin is a hormone secreted from white adipocytes and takes part in the regulation of several metabolic processes. Although the pathophysiological importance of adiponectin has been thoroughly investigated, the mechanisms controlling its release are only partly understood. We have recently shown that adiponectin is secreted via regulated exocytosis of adiponectin-containing vesicles, that adiponectin exocytosis is stimulated by cAMP-dependent mechanisms, and that Ca2+ and ATP augment the cAMP-triggered secretion. However, much remains to be discovered regarding the molecular and cellular regulation of adiponectin release. Here, we have used mathematical modeling to extract detailed information contained within our previously obtained high-resolution patch-clamp time-resolved capacitance recordings to produce the first model of adiponectin exocytosis/secretion that combines all mechanistic knowledge deduced from electrophysiological experimental series. This model demonstrates that our previous understanding of the role of intracellular ATP in the control of adiponectin exocytosis needs to be revised to include an additional ATP-dependent step. Validation of the model by introduction of data of secreted adiponectin yielded a very close resemblance between the simulations and experimental results. Moreover, we could show that Ca2+-dependent adiponectin endocytosis contributes to the measured capacitance signal, and we were able to predict the contribution of endocytosis to the measured exocytotic rate under different experimental conditions. In conclusion, using mathematical modeling of published and newly generated data, we have obtained estimates of adiponectin exo- and endocytosis rates, and we have predicted adiponectin secretion. We believe that our model should have multiple applications in the study of metabolic processes and hormonal control thereof.
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Affiliation(s)
- Cecilia Brännmark
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg
| | - William Lövfors
- Departments of Biomedical Engineering, SE-581 83 Linköping; Mathematics, Linköping University, SE-581 83 Linköping
| | - Ali M Komai
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg
| | - Tom Axelsson
- Departments of Biomedical Engineering, SE-581 83 Linköping
| | - Mickaël F El Hachmane
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg
| | - Saliha Musovic
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg
| | - Alexandra Paul
- Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10 SE-412 96 Göteborg
| | - Elin Nyman
- Departments of Biomedical Engineering, SE-581 83 Linköping; Cardiovascular and Metabolic Diseases iMed Biotech Unit, AstraZeneca R&D, 431 83 Gothenburg, Sweden.
| | - Charlotta S Olofsson
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg.
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15
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Yue HY, Bieberich E, Xu J. Promotion of endocytosis efficiency through an ATP-independent mechanism at rat calyx of Held terminals. J Physiol 2017; 595:5265-5284. [PMID: 28555839 DOI: 10.1113/jp274275] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Accepted: 05/15/2017] [Indexed: 01/14/2023] Open
Abstract
KEY POINTS At rat calyx of Held terminals, ATP was required not only for slow endocytosis, but also for rapid phase of compensatory endocytosis. An ATP-independent form of endocytosis was recruited to accelerate membrane retrieval at increased activity and temperature. ATP-independent endocytosis primarily involved retrieval of pre-existing membrane, which depended on Ca2+ and the activity of neutral sphingomyelinase but not clathrin-coated pit maturation. ATP-independent endocytosis represents a non-canonical mechanism that can efficiently retrieve membrane at physiological conditions without competing for the limited ATP at elevated neuronal activity. ABSTRACT Neurotransmission relies on membrane endocytosis to maintain vesicle supply and membrane stability. Endocytosis has been generally recognized as a major ATP-dependent function, which efficiently retrieves more membrane at elevated neuronal activity when ATP consumption within nerve terminals increases drastically. This paradox raises the interesting question of whether increased activity recruits ATP-independent mechanism(s) to accelerate endocytosis at the same time as preserving ATP availability for other tasks. To address this issue, we studied ATP requirement in three typical forms of endocytosis at rat calyx of Held terminals by whole-cell membrane capacitance measurements. At room temperature, blocking ATP hydrolysis effectively abolished slow endocytosis and rapid endocytosis but only partially inhibited excess endocytosis following intense stimulation. The ATP-independent endocytosis occurred at calyces from postnatal days 8-15, suggesting its existence before and after hearing onset. This endocytosis was not affected by a reduction of exocytosis using the light chain of botulinum toxin C, nor by block of clathrin-coat maturation. It was abolished by EGTA, which preferentially blocked endocytosis of retrievable membrane pre-existing at the surface, and was impaired by oxidation of cholesterol and inhibition of neutral sphingomyelinase. ATP-independent endocytosis became more significant at 34-35°C, and recovered membrane by an amount that, on average, was close to exocytosis. The results of the present study suggest that activity and temperature recruit ATP-independent endocytosis of pre-existing membrane (in addition to ATP-dependent endocytosis) to efficiently retrieve membrane at nerve terminals. This less understood endocytosis represents a non-canonical mechanism regulated by lipids such as cholesterol and sphingomyelinase.
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Affiliation(s)
- Hai-Yuan Yue
- Departments of Neuroscience and Regenerative Medicine, Augusta University, USA
| | - Erhard Bieberich
- Departments of Neuroscience and Regenerative Medicine, Augusta University, USA
| | - Jianhua Xu
- Departments of Neuroscience and Regenerative Medicine, Augusta University, USA.,Department of Neurology, Medical College of Georgia, Augusta University, USA
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16
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Xie Z, Long J, Liu J, Chai Z, Kang X, Wang C. Molecular Mechanisms for the Coupling of Endocytosis to Exocytosis in Neurons. Front Mol Neurosci 2017; 10:47. [PMID: 28348516 PMCID: PMC5346583 DOI: 10.3389/fnmol.2017.00047] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 02/10/2017] [Indexed: 11/13/2022] Open
Abstract
Neuronal communication and brain function mainly depend on the fundamental biological events of neurotransmission, including the exocytosis of presynaptic vesicles (SVs) for neurotransmitter release and the subsequent endocytosis for SV retrieval. Neurotransmitters are released through the Ca2+- and SNARE-dependent fusion of SVs with the presynaptic plasma membrane. Following exocytosis, endocytosis occurs immediately to retrieve SV membrane and fusion machinery for local recycling and thus maintain the homeostasis of synaptic structure and sustained neurotransmission. Apart from the general endocytic machinery, recent studies have also revealed the involvement of SNARE proteins (synaptobrevin, SNAP25 and syntaxin), synaptophysin, Ca2+/calmodulin, and members of the synaptotagmin protein family (Syt1, Syt4, Syt7 and Syt11) in the balance and tight coupling of exo-endocytosis in neurons. Here, we provide an overview of recent progress in understanding how these neuron-specific adaptors coordinate to ensure precise and efficient endocytosis during neurotransmission.
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Affiliation(s)
- Zhenli Xie
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong UniversityXi'an, China; Frontier Institute of Science and Technology, Xi'an Jiaotong UniversityXi'an, China; State Key Laboratory of Membrane Biology, Peking UniversityBeijing, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking UniversityBeijing, China
| | - Jiangang Long
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong UniversityXi'an, China; Frontier Institute of Science and Technology, Xi'an Jiaotong UniversityXi'an, China
| | - Jiankang Liu
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong UniversityXi'an, China; Frontier Institute of Science and Technology, Xi'an Jiaotong UniversityXi'an, China
| | - Zuying Chai
- State Key Laboratory of Membrane Biology, Peking UniversityBeijing, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking UniversityBeijing, China
| | - Xinjiang Kang
- State Key Laboratory of Membrane Biology, Peking UniversityBeijing, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking UniversityBeijing, China; College of Life Sciences, Liaocheng UniversityLiaocheng, China; Key Laboratory of Medical Electrophysiology, Ministry of Education of China, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical UniversityLuzhou, China
| | - Changhe Wang
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong UniversityXi'an, China; Frontier Institute of Science and Technology, Xi'an Jiaotong UniversityXi'an, China; State Key Laboratory of Membrane Biology, Peking UniversityBeijing, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking UniversityBeijing, China
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17
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Moya-Díaz J, Álvarez YD, Montenegro M, Bayonés L, Belingheri AV, González-Jamett AM, Cárdenas AM, Marengo FD. Sustained Exocytosis after Action Potential-Like Stimulation at Low Frequencies in Mouse Chromaffin Cells Depends on a Dynamin-Dependent Fast Endocytotic Process. Front Cell Neurosci 2016; 10:184. [PMID: 27507935 PMCID: PMC4960491 DOI: 10.3389/fncel.2016.00184] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 07/08/2016] [Indexed: 12/17/2022] Open
Abstract
Under basal conditions the action potential firing rate of adrenal chromaffin cells is lower than 0.5 Hz. The maintenance of the secretory response at such frequencies requires a continuous replenishment of releasable vesicles. However, the mechanism that allows such vesicle replenishment remains unclear. Here, using membrane capacitance measurements on mouse chromaffin cells, we studied the mechanism of replenishment of a group of vesicles released by a single action potential-like stimulus (APls). The exocytosis triggered by APls (ETAP) represents a fraction (40%) of the immediately releasable pool, a group of vesicles highly coupled to voltage dependent calcium channels. ETAP was replenished with a time constant of 0.73 ± 0.11 s, fast enough to maintain synchronous exocytosis at 0.2–0.5 Hz stimulation. Regarding the mechanism involved in rapid ETAP replenishment, we found that it depends on the ready releasable pool; indeed depletion of this vesicle pool significantly delays ETAP replenishment. On the other hand, ETAP replenishment also correlates with a dynamin-dependent fast endocytosis process (τ = 0.53 ± 0.01 s). In this regard, disruption of dynamin function markedly inhibits the fast endocytosis and delays ETAP replenishment, but also significantly decreases the synchronous exocytosis during repetitive APls stimulation at low frequencies (0.2 and 0.5 Hz). Considering these findings, we propose a model in where both the transfer of vesicles from ready releasable pool and fast endocytosis allow rapid ETAP replenishment during low stimulation frequencies.
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Affiliation(s)
- José Moya-Díaz
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Instituto de Fisiología, Biología Molecular y Neurociencias, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas Buenos Aires, Argentina
| | - Yanina D Álvarez
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Instituto de Fisiología, Biología Molecular y Neurociencias, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas Buenos Aires, Argentina
| | - Mauricio Montenegro
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Instituto de Fisiología, Biología Molecular y Neurociencias, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas Buenos Aires, Argentina
| | - Lucas Bayonés
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Instituto de Fisiología, Biología Molecular y Neurociencias, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas Buenos Aires, Argentina
| | - Ana V Belingheri
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Instituto de Fisiología, Biología Molecular y Neurociencias, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas Buenos Aires, Argentina
| | - Arlek M González-Jamett
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso Valparaíso, Chile
| | - Ana M Cárdenas
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso Valparaíso, Chile
| | - Fernando D Marengo
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Instituto de Fisiología, Biología Molecular y Neurociencias, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas Buenos Aires, Argentina
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18
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Post-fusion structural changes and their roles in exocytosis and endocytosis of dense-core vesicles. Nat Commun 2015; 5:3356. [PMID: 24561832 PMCID: PMC4267856 DOI: 10.1038/ncomms4356] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 01/30/2014] [Indexed: 12/18/2022] Open
Abstract
Vesicle fusion with the plasma membrane generates an Ω-shaped membrane profile. Its pore is thought to dilate until flattening (full-collapse), followed by classical endocytosis to retrieve vesicles. Alternatively, the pore may close (kiss-and-run), but the triggering mechanisms and its endocytic roles remain poorly understood. Here, using confocal and stimulated emission depletion microscopy imaging of dense-core vesicles, we find that fusion-generated Ω-profiles may enlarge or shrink while maintaining vesicular membrane proteins. Closure of fusion-generated Ω-profiles, which produces various sizes of vesicles, is the dominant mechanism mediating rapid and slow endocytosis within ~1-30 s. Strong calcium influx triggers dynamin-mediated closure. Weak calcium influx does not promote closure, but facilitates the merging of Ω-profiles with the plasma membrane via shrinking rather than full-collapse. These results establish a model, termed Ω-exo-endocytosis, in which the fusion-generated Ω-profile may shrink to merge with the plasma membrane, change in size or change in size then close in response to calcium, which is the main mechanism to retrieve dense-core vesicles.
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19
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Craviso GL, Fisher C, Chatterjee I, Thomas Vernier P. Adrenal chromaffin cells do not swell when exposed to nanosecond electric pulses. Bioelectrochemistry 2015; 103:98-102. [DOI: 10.1016/j.bioelechem.2014.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 07/22/2014] [Accepted: 08/12/2014] [Indexed: 12/16/2022]
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20
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Abstract
Ca(2+)-dependent synaptic vesicle recycling is essential for structural homeostasis of synapses and maintenance of neurotransmission. Although, the executive role of intrasynaptic Ca(2+) transients in synaptic vesicle exocytosis is well established, identifying the exact role of Ca(2+) in endocytosis has been difficult. In some studies, Ca(2+) has been suggested as an essential trigger required to initiate synaptic vesicle retrieval, whereas others manipulating synaptic Ca(2+) concentrations reported a modulatory role for Ca(2+) leading to inhibition or acceleration of endocytosis. Molecular studies of synaptic vesicle endocytosis, on the other hand, have consistently focused on the roles of Ca(2+)-calmodulin dependent phosphatase calcineurin and synaptic vesicle protein synaptotagmin as potential Ca(2+) sensors for endocytosis. Most studies probing the role of Ca(2+) in endocytosis have relied on measurements of synaptic vesicle retrieval after strong stimulation. Strong stimulation paradigms elicit fusion and retrieval of multiple synaptic vesicles and therefore can be affected by several factors besides the kinetics and duration of Ca(2+) signals that include the number of exocytosed vesicles and accumulation of released neurotransmitters thus altering fusion and retrieval processes indirectly via retrograde signaling. Studies monitoring single synaptic vesicle endocytosis may help resolve this conundrum as in these settings the impact of Ca(2+) on synaptic fusion probability can be uncoupled from its putative role on synaptic vesicle retrieval. Future experiments using these single vesicle approaches will help dissect the specific role(s) of Ca(2+) and its sensors in synaptic vesicle endocytosis.
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Affiliation(s)
- Jeremy Leitz
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, USA
| | - Ege T Kavalali
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, USA Department of Physiology, UT Southwestern Medical Center, Dallas, TX, USA
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21
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Yue HY, Xu J. Cholesterol regulates multiple forms of vesicle endocytosis at a mammalian central synapse. J Neurochem 2015; 134:247-60. [PMID: 25893258 DOI: 10.1111/jnc.13129] [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: 12/11/2014] [Revised: 03/01/2015] [Accepted: 03/31/2015] [Indexed: 01/10/2023]
Abstract
Endocytosis in synapses sustains neurotransmission by recycling vesicle membrane and maintaining the homeostasis of synaptic membrane. A role of membrane cholesterol in synaptic endocytosis remains controversial because of conflicting observations, technical limitations in previous studies, and potential interference from non-specific effects after cholesterol manipulation. Furthermore, it remains unclear whether cholesterol participates in distinct forms of endocytosis that function under different activity levels. In this study, applying the whole-cell membrane capacitance measurement to monitor endocytosis in real time at the rat calyx of Held terminals, we found that disrupting cholesterol with dialysis of cholesterol oxidase or methyl-β-cyclodextrin impaired three different forms of endocytosis, including slow endocytosis, rapid endocytosis, and endocytosis of the retrievable membrane that exists at the surface before stimulation. The effects were observed when disruption of cholesterol was mild enough not to change Ca(2+) channel current or vesicle exocytosis, indicative of stringent cholesterol requirement in synaptic endocytosis. Extracting cholesterol with high concentrations of methyl-β-cyclodextrin reduced exocytosis, mainly by decreasing the readily releasable pool and the vesicle replenishment after readily releasable pool depletion. Our study suggests that cholesterol is an important, universal regulator in multiple forms of vesicle endocytosis at mammalian central synapses.
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Affiliation(s)
- Hai-Yuan Yue
- Department of Neuroscience and Regenerative Medicine, Georgia Regents University, Augusta, Georgia, USA
| | - Jianhua Xu
- Department of Neuroscience and Regenerative Medicine, Georgia Regents University, Augusta, Georgia, USA.,Department of Neurology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA
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22
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Rao TC, Passmore DR, Peleman AR, Das M, Chapman ER, Anantharam A. Distinct fusion properties of synaptotagmin-1 and synaptotagmin-7 bearing dense core granules. Mol Biol Cell 2014; 25:2416-27. [PMID: 24943843 PMCID: PMC4142614 DOI: 10.1091/mbc.e14-02-0702] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Adrenal chromaffin cells express two synaptotagmin isoforms, Syt-1 and Syt-7. Isoforms are usually sorted to separate secretory granules, are differentially activated by depolarizing stimuli, and favor discrete modes of exocytosis. It is proposed that stimulus/Ca+-dependent secretion in the chromaffin cell relies on selective Syt isoform activation. Adrenal chromaffin cells release hormones and neuropeptides that are essential for physiological homeostasis. During this process, secretory granules fuse with the plasma membrane and deliver their cargo to the extracellular space. It was once believed that fusion was the final regulated step in exocytosis, resulting in uniform and total release of granule cargo. Recent evidence argues for nonuniform outcomes after fusion, in which cargo is released with variable kinetics and selectivity. The goal of this study was to identify factors that contribute to the different outcomes, with a focus on the Ca2+-sensing synaptotagmin (Syt) proteins. Two Syt isoforms are expressed in chromaffin cells: Syt-1 and Syt-7. We find that overexpressed and endogenous Syt isoforms are usually sorted to separate secretory granules and are differentially activated by depolarizing stimuli. In addition, overexpressed Syt-1 and Syt-7 impose distinct effects on fusion pore expansion and granule cargo release. Syt-7 pores usually fail to expand (or reseal), slowing the dispersal of lumenal cargo proteins and granule membrane proteins. On the other hand, Syt-1 diffuses from fusion sites and promotes the release of lumenal cargo proteins. These findings suggest one way in which chromaffin cells may regulate cargo release is via differential activation of synaptotagmin isoforms.
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Affiliation(s)
- Tejeshwar C Rao
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | - Daniel R Passmore
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | - Andrew R Peleman
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | - Madhurima Das
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | - Edwin R Chapman
- Howard Hughes Medical Institute, Department of Neuroscience, University of Wisconsin, Madison, WI 53705
| | - Arun Anantharam
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
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Wu XS, Zhang Z, Zhao WD, Wang D, Luo F, Wu LG. Calcineurin is universally involved in vesicle endocytosis at neuronal and nonneuronal secretory cells. Cell Rep 2014; 7:982-8. [PMID: 24835995 DOI: 10.1016/j.celrep.2014.04.020] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 03/05/2014] [Accepted: 04/11/2014] [Indexed: 01/28/2023] Open
Abstract
Calcium influx triggers and accelerates endocytosis in nerve terminals and nonneuronal secretory cells. Whether calcium/calmodulin-activated calcineurin, which dephosphorylates endocytic proteins, mediates this process is highly controversial for different cell types, developmental stages, and endocytic forms. Using three preparations that previously produced discrepant results (i.e., large calyx-type synapses, conventional cerebellar synapses, and neuroendocrine chromaffin cells containing large dense-core vesicles), we found that calcineurin gene knockout consistently slowed down endocytosis, regardless of cell type, developmental stage, or endocytic form (rapid or slow). In contrast, calcineurin and calmodulin blockers slowed down endocytosis at a relatively small calcium influx, but did not inhibit endocytosis at a large calcium influx, resulting in false-negative results. These results suggest that calcineurin is universally involved in endocytosis. They may also help explain the discrepancies among previous pharmacological studies. We therefore suggest that calcineurin should be included as a key player in mediating calcium-triggered and -accelerated vesicle endocytosis.
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Affiliation(s)
- Xin-Sheng Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Zhen Zhang
- National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Wei-Dong Zhao
- National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Dongsheng Wang
- National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Fujun Luo
- National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA.
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Bui L, Glavinović MI. Temperature dependence of vesicular dynamics at excitatory synapses of rat hippocampus. Cogn Neurodyn 2014; 8:277-86. [PMID: 25009670 DOI: 10.1007/s11571-014-9283-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 01/27/2014] [Accepted: 02/09/2014] [Indexed: 10/25/2022] Open
Abstract
How vesicular dynamics parameters depend on temperature and how temperature affects the parameter change during prolonged high frequency stimulation was determined by fitting a model of vesicular storage and release to the amplitudes of the excitatory post-synaptic currents (EPSC) recorded from CA1 neurons in rat hippocampal slices. The temperature ranged from low (13 °C) to higher and more physiological temperature (34 °C). Fitting the model of vesicular storage and release to the EPSC amplitudes during a single pair of brief high-low frequency stimulation trains yields the estimates of all parameters of the vesicular dynamics, and with good precision. Both fractional release and replenishment rate decrease as the temperature rises. Change of the underlying 'basic' parameters (release coupling, replenishment coupling and readily releasable pool size), which the model-fitting also yields is complex. The replenishment coupling between the readily releasable pool (RRP) and resting pool increases with temperature (which renders the replenishment rate higher), but this is more than counterbalanced by greater RRP size (which renders the replenishment rate lower). Finally, during long, high frequency patterned stimulation that leads to significant synaptic depression, the replenishment rate decreases markedly and rapidly at low temperatures (<22 °C), but at high temperatures (>28 °C) the replenishment rate rises with stimulation, making synapses better able to maintain synaptic efficacy.
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Affiliation(s)
- Loc Bui
- Department of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, PQ H3G 1Y6 Canada
| | - Mladen I Glavinović
- Department of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, PQ H3G 1Y6 Canada
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Samasilp P, Lopin K, Chan SA, Ramachandran R, Smith C. Syndapin 3 modulates fusion pore expansion in mouse neuroendocrine chromaffin cells. Am J Physiol Cell Physiol 2014; 306:C831-43. [PMID: 24500282 DOI: 10.1152/ajpcell.00291.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adrenal neuroendocrine chromaffin cells receive excitatory synaptic input from the sympathetic nervous system and secrete hormones into the peripheral circulation. Under basal sympathetic tone, modest amounts of freely soluble catecholamine are selectively released through a restricted fusion pore formed between the secretory granule and the plasma membrane. Upon activation of the sympathoadrenal stress reflex, elevated stimulation drives fusion pore expansion, resulting in increased catecholamine secretion and facilitating release of copackaged peptide hormones. Thus regulated expansion of the secretory fusion pore is a control point for differential hormone release of the sympathoadrenal stress response. Previous work has shown that syndapin 1 deletion alters transmitter release and that the dynamin 1-syndapin 1 interaction is necessary for coupled endocytosis in neurons. Dynamin has also been shown to be involved in regulation of fusion pore expansion in neuroendocrine chromaffin cells through an activity-dependent association with syndapin. However, it is not known which syndapin isoform(s) contributes to pore dynamics in neuroendocrine cells. Nor is it known at what stage of the secretion process dynamin and syndapin associate to modulate pore expansion. Here we investigate the expression and localization of syndapin isoforms and determine which are involved in mediating fusion pore expansion. We show that all syndapin isoforms are expressed in the adrenal medulla. Mutation of the SH3 dynamin-binding domain of all syndapin isoforms shows that fusion pore expansion and catecholamine release are limited specifically by mutation of syndapin 3. The mutation also disrupts targeting of syndapin 3 to the cell periphery. Syndapin 3 exists in a persistent colocalized state with dynamin 1.
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Affiliation(s)
- Prattana Samasilp
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio; and
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Abstract
Large dense core vesicle (LDCV) exocytosis in chromaffin cells follows a well characterized process consisting of docking, priming, and fusion. Total internal reflection fluorescence microscopy (TIRFM) studies suggest that some LDCVs, although being able to dock, are resistant to calcium-triggered release. This phenomenon termed dead-end docking has not been investigated until now. We characterized dead-end vesicles using a combination of membrane capacitance measurement and visualization of LDCVs with TIRFM. Stimulation of bovine chromaffin cells for 5 min with 6 μm free intracellular Ca2+ induced strong secretion and a large reduction of the LDCV density at the plasma membrane. Approximately 15% of the LDCVs were visible at the plasma membrane throughout experiments, indicating they were permanently docked dead-end vesicles. Overexpression of Munc18-2 or SNAP-25 reduced the fraction of dead-end vesicles. Conversely, expressing open-syntaxin increased the fraction of dead-end vesicles. These results indicate the existence of the unproductive target soluble N-ethylmaleimide-sensitive factor attachment protein receptor acceptor complex composed of 2:1 syntaxin-SNAP-25 in vivo. More importantly, they define a novel function for this acceptor complex in mediating dead-end docking.
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Wu LG, Hamid E, Shin W, Chiang HC. Exocytosis and endocytosis: modes, functions, and coupling mechanisms. Annu Rev Physiol 2013; 76:301-31. [PMID: 24274740 DOI: 10.1146/annurev-physiol-021113-170305] [Citation(s) in RCA: 287] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Vesicle exocytosis releases content to mediate many biological events, including synaptic transmission essential for brain functions. Following exocytosis, endocytosis is initiated to retrieve exocytosed vesicles within seconds to minutes. Decades of studies in secretory cells reveal three exocytosis modes coupled to three endocytosis modes: (a) full-collapse fusion, in which vesicles collapse into the plasma membrane, followed by classical endocytosis involving membrane invagination and vesicle reformation; (b) kiss-and-run, in which the fusion pore opens and closes; and (c) compound exocytosis, which involves exocytosis of giant vesicles formed via vesicle-vesicle fusion, followed by bulk endocytosis that retrieves giant vesicles. Here we review these exo- and endocytosis modes and their roles in regulating quantal size and synaptic strength, generating synaptic plasticity, maintaining exocytosis, and clearing release sites for vesicle replenishment. Furthermore, we highlight recent progress in understanding how vesicle endocytosis is initiated and is thus coupled to exocytosis. The emerging model is that calcium influx via voltage-dependent calcium channels at the calcium microdomain triggers endocytosis and controls endocytosis rate; calmodulin and synaptotagmin are the calcium sensors; and the exocytosis machinery, including SNARE proteins (synaptobrevin, SNAP25, and syntaxin), is needed to coinitiate endocytosis, likely to control the amount of endocytosis.
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Affiliation(s)
- Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, Maryland 20892; ,
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Voltage-gated Ca2+ influx and mitochondrial Ca2+ initiate secretion from Aplysia neuroendocrine cells. Neuroscience 2013; 250:755-72. [PMID: 23876326 DOI: 10.1016/j.neuroscience.2013.07.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 07/10/2013] [Accepted: 07/11/2013] [Indexed: 01/14/2023]
Abstract
Neuroendocrine secretion often requires prolonged voltage-gated Ca(2+) entry; however, the ability of Ca(2+) from intracellular stores, such as endoplasmic reticulum or mitochondria, to elicit secretion is less clear. We examined this using the bag cell neurons, which trigger ovulation in Aplysia by releasing egg-laying hormone (ELH) peptide. Secretion from cultured bag cell neurons was observed as an increase in plasma membrane capacitance following Ca(2+) influx evoked by a 5-Hz, 1-min train of depolarizing steps under voltage-clamp. The response was similar for step durations of ≥ 50 ms, but fell off sharply with shorter stimuli. The capacitance change was attenuated by replacing external Ca(2+) with Ba(2+), blocking Ca(2+) channels, buffering intracellular Ca(2+) with EGTA, disrupting synaptic protein recycling, or genetic knock-down of ELH. Regarding intracellular stores, liberating mitochondrial Ca(2+) with the protonophore, carbonyl cyanide-p-trifluoromethoxyphenyl-hydrazone (FCCP), brought about an EGTA-sensitive elevation of capacitance. Conversely, no change was observed to Ca(2+) released from the endoplasmic reticulum or acidic stores. Prior exposure to FCCP lessened the train-induced capacitance increase, suggesting overlap in the pool of releasable vesicles. Employing GTP-γ-S to interfere with endocytosis delayed recovery (presumed membrane retrieval) of the capacitance change following FCCP, but not the train. Finally, secretion was correlated with reproductive behavior, in that neurons isolated from animals engaged in egg-laying presented a greater train-induced capacitance elevation vs quiescent animals. The bag cell neuron capacitance increase is consistent with peptide secretion requiring high Ca(2+), either from influx or stores, and may reflect the all-or-none nature of reproduction.
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Vandael DHF, Mahapatra S, Calorio C, Marcantoni A, Carbone E. Cav1.3 and Cav1.2 channels of adrenal chromaffin cells: emerging views on cAMP/cGMP-mediated phosphorylation and role in pacemaking. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1608-18. [PMID: 23159773 DOI: 10.1016/j.bbamem.2012.11.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 11/05/2012] [Accepted: 11/08/2012] [Indexed: 12/21/2022]
Abstract
Voltage-gated Ca²⁺ channels (VGCCs) are voltage sensors that convert membrane depolarizations into Ca²⁺ signals. In the chromaffin cells of the adrenal medulla, the Ca²⁺ signals driven by VGCCs regulate catecholamine secretion, vesicle retrievals, action potential shape and firing frequency. Among the VGCC-types expressed in these cells (N-, L-, P/Q-, R- and T-types), the two L-type isoforms, Ca(v)1.2 and Ca(v)1.3, control key activities due to their particular activation-inactivation gating and high-density of expression in rodents and humans. The two isoforms are also effectively modulated by G protein-coupled receptor pathways delimited in membrane micro-domains and by the cAMP/PKA and NO/cGMP/PKG phosphorylation pathways which induce prominent Ca²⁺ current changes if opposingly regulated. The two L-type isoforms shape the action potential and directly participate to vesicle exocytosis and endocytosis. The low-threshold of activation and slow rate of inactivation of Ca(v)1.3 confer to this channel the unique property of carrying sufficient inward current at subthreshold potentials able to activate BK and SK channels which set the resting potential, the action potential shape, the cell firing mode and the degree of spike frequency adaptation during spontaneous firing or sustained depolarizations. These properties help chromaffin cells to optimally adapt when switching from normal to stress-mimicking conditions. Here, we will review past and recent findings on cAMP- and cGMP-mediated modulations of Ca(v)1.2 and Ca(v)1.3 and the role that these channels play in the control of chromaffin cell firing. This article is part of a Special Issue entitled: Calcium channels.
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Affiliation(s)
- D H F Vandael
- Department of Drug Science, Laboratory of Cellular & Molecular Neuroscience, NIS Center, CNISM, University of Torino, Italy
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Activity-dependent fusion pore expansion regulated by a calcineurin-dependent dynamin-syndapin pathway in mouse adrenal chromaffin cells. J Neurosci 2012; 32:10438-47. [PMID: 22836276 DOI: 10.1523/jneurosci.1299-12.2012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Neuroendocrine chromaffin cells selectively secrete a variety of transmitter molecules into the circulation as a function of sympathetic activation. Activity-dependent release of transmitter species is controlled through regulation of the secretory fusion pore. Under sympathetic tone, basal synaptic excitation drives chromaffin cells to selectively secrete modest levels of catecholamine through a restricted secretory fusion pore. In contrast, elevated sympathetic activity, experienced under stress, results in fusion pore expansion to evoke maximal catecholamine release and to facilitate release of copackaged peptide transmitters. Therefore, fusion pore expansion is a key control point for the activation of the sympatho-adrenal stress response. Despite the physiological importance of this process, the molecular mechanism by which it is regulated remains unclear. Here we employ fluorescence imaging with electrophysiological and electrochemical-based approaches to investigate the role of dynamin I in the regulation of activity-mediated fusion pore expansion in mouse adrenal chromaffin cells. We show that under elevated stimulation, dynamin I is dephosphorylated at Ser-774 by calcineurin. We also demonstrate that disruption of dynamin I-syndapin binding, an association regulated by calcineurin-dependent dynamin dephosphorylation, limits fusion pore expansion. Last, we show that perturbation of N-WASP function (a syndapin substrate) limits activity-mediated fusion pore expansion. Our results suggest that fusion pore expansion is regulated by a calcineurin-dependent dephosphorylation of dynamin I. Dephosphorylated dynamin I acts via a syndapin/N-WASP signaling cascade to mediate pore expansion.
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31
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Yamashita T. Ca2+-dependent regulation of synaptic vesicle endocytosis. Neurosci Res 2012; 73:1-7. [DOI: 10.1016/j.neures.2012.02.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 02/16/2012] [Accepted: 02/17/2012] [Indexed: 01/25/2023]
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Cytosolic organelles shape calcium signals and exo–endocytotic responses of chromaffin cells. Cell Calcium 2012; 51:309-20. [DOI: 10.1016/j.ceca.2011.12.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 12/02/2011] [Accepted: 12/05/2011] [Indexed: 01/09/2023]
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Perez Bay AE, Belingheri AV, Alvarez YD, Marengo FD. Membrane cycling after the excess retrieval mode of rapid endocytosis in mouse chromaffin cells. Acta Physiol (Oxf) 2012; 204:403-18. [PMID: 21791014 DOI: 10.1111/j.1748-1716.2011.02340.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM After exocytosis, neuroendocrine cells and neurones keep constant the plasma membrane and the releasable vesicle pools by performing endocytosis and vesicular cycling. Patch-clamp capacitance measurements on chromaffin cells showed that strong Ca(+2) entry activates excess retrieval: a rapid endocytosis process that retrieves more membrane than the one fused by preceding exocytosis. The main purpose of the present experiments was to study the recycling pathway that follows excess retrieval, which is unknown. METHODS Membrane recycling after exocytosis-endocytosis can be studied by fluorescence imaging assays with FM1-43 (Perez Bay et al. Am J Physiol Cell Physiol 2007; 293, C1509). In this work, we used this assay in combination with fluorescent dextrans and specific organelle-targeted antibodies to study the membrane recycling after excess retrieval in mouse chromaffin cells. RESULTS Excess retrieval was observed after the application of high-K(+) or cholinergic agonists during 15 or 30 s in the presence of FM1-43. We found that the excess retrieval membrane pool (defined as endocytosis-exocytosis) was associated with the generation of a non-releasable fraction of membrane (up to 30% of plasma membrane surface) colocalizing with the lysosomal compartment. The excess retrieval membrane pool followed a saturable cytosolic Ca(2+) dependency, and it was suppressed by inhibitors of L-type Ca(2+) channels, endoplasmic reticulum Ca(2+) release and PKC. CONCLUSION Excess retrieval is not associated with the cycling of releasable vesicles, but it is related to the formation of non-releasable endosomes. This process is activated by a concerted contribution of Ca(2+) entry through L-channels and Ca(2+) release from endoplasmic reticulum.
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Affiliation(s)
- A E Perez Bay
- Laboratorio de Fisiología y Biología Molecular, Departamento de Fisiología y Biología Molecular y Celular, Instituto de Fisiología, Biología Molecular y Neurociencias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina
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Xue J, Graham ME, Novelle AE, Sue N, Gray N, McNiven MA, Smillie KJ, Cousin MA, Robinson PJ. Calcineurin selectively docks with the dynamin Ixb splice variant to regulate activity-dependent bulk endocytosis. J Biol Chem 2011; 286:30295-30303. [PMID: 21730063 DOI: 10.1074/jbc.m111.273110] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Depolarization of nerve terminals stimulates rapid dephosphorylation of two isoforms of dynamin I (dynI), mediated by the calcium-dependent phosphatase calcineurin (CaN). Dephosphorylation at the major phosphorylation sites Ser-774/778 promotes a dynI-syndapin I interaction for a specific mode of synaptic vesicle endocytosis called activity-dependent bulk endocytosis (ADBE). DynI has two main splice variants at its extreme C terminus, long or short (dynIxa and dynIxb) varying only by 20 (xa) or 7 (xb) residues. Recombinant GST fusion proteins of dynIxa and dynIxb proline-rich domains (PRDs) were used to pull down interacting proteins from rat brain nerve terminals. Both bound equally to syndapin, but dynIxb PRD exclusively bound to the catalytic subunit of CaNA, which recruited CaNB. Binding of CaN was increased in the presence of calcium and was accompanied by further recruitment of calmodulin. Point mutations showed that the entire C terminus of dynIxb is a CaN docking site related to a conserved CaN docking motif (PXIXI(T/S)). This sequence is unique to dynIxb among all other dynamin variants or genes. Peptide mimetics of the dynIxb tail blocked CaN binding in vitro and selectively inhibited depolarization-evoked dynI dephosphorylation in nerve terminals but not of other dephosphins. Therefore, docking to dynIxb is required for the regulation of both dynI splice variants, yet it does not regulate the phosphorylation cycle of other dephosphins. The peptide blocked ADBE, but not clathrin-mediated endocytosis of synaptic vesicles. Our results indicate that Ca(2+) influx regulates assembly of a fully active CaN-calmodulin complex selectively on the tail of dynIxb and that the complex is recruited to sites of ADBE in nerve terminals.
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Affiliation(s)
- Jing Xue
- Cell Signalling Unit, Children's Medical Research Institute, University of Sydney, Locked Bag 23, Wentworthville 2145, New South Wales, Australia
| | - Mark E Graham
- Cell Signalling Unit, Children's Medical Research Institute, University of Sydney, Locked Bag 23, Wentworthville 2145, New South Wales, Australia
| | - Aimee E Novelle
- Cell Signalling Unit, Children's Medical Research Institute, University of Sydney, Locked Bag 23, Wentworthville 2145, New South Wales, Australia
| | - Nancy Sue
- Cell Signalling Unit, Children's Medical Research Institute, University of Sydney, Locked Bag 23, Wentworthville 2145, New South Wales, Australia
| | - Noah Gray
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905
| | - Mark A McNiven
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905
| | - Karen J Smillie
- Membrane Biology Group, Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh EH8 9XD, United Kingdom
| | - Michael A Cousin
- Membrane Biology Group, Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh EH8 9XD, United Kingdom
| | - Phillip J Robinson
- Cell Signalling Unit, Children's Medical Research Institute, University of Sydney, Locked Bag 23, Wentworthville 2145, New South Wales, Australia.
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Chan SA, Doreian B, Smith C. Dynamin and myosin regulate differential exocytosis from mouse adrenal chromaffin cells. Cell Mol Neurobiol 2011; 30:1351-7. [PMID: 21061163 DOI: 10.1007/s10571-010-9591-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 09/02/2010] [Indexed: 01/27/2023]
Abstract
Neuroendocrine chromaffin cells of the adrenal medulla represent a primary output for the sympathetic nervous system. Chromaffin cells release catecholamine as well as vaso- and neuro-active peptide transmitters into the circulation through exocytic fusion of large dense-core secretory granules. Under basal sympathetic activity, chromaffin cells selectively release modest levels of catecholamines, helping to set the "rest and digest" status of energy storage. Under stress activation, elevated sympathetic firing leads to increased catecholamine as well as peptide transmitter release to set the "fight or flight" status of energy expenditure. While the mechanism for catecholamine release has been widely investigated, relatively little is known of how peptide transmitter release is regulated to occur selectively under elevated stimulation. Recent studies have shown selective catecholamine release under basal stimulation is accomplished through a transient, restricted exocytic fusion pore between granule and plasma membrane, releasing a soluble fraction of the small, diffusible molecules. Elevated cell firing leads to the active dilation of the fusion pore, leading to the release of both catecholamine and the less diffusible peptide transmitters. Here we propose a molecular mechanism regulating the activity-dependent dilation of the fusion pore. We review the immediate literature and provide new data to formulate a working mechanistic hypothesis whereby calcium-mediated dephosphorylation of dynamin I at Ser-774 leads to the recruitment of the molecular motor myosin II to actively dilate the fusion pore to facilitate release of peptide transmitters. Thus, activity-dependent dephosphorylation of dynamin is hypothesized to represent a key molecular step in the sympatho-adrenal stress response.
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Affiliation(s)
- Shyue-An Chan
- Case Western Reserve University, 2109 Adelbert Road, Cleveland, OH 44106-4970, USA.
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Lariccia V, Fine M, Magi S, Lin MJ, Yaradanakul A, Llaguno MC, Hilgemann DW. Massive calcium-activated endocytosis without involvement of classical endocytic proteins. ACTA ACUST UNITED AC 2011; 137:111-32. [PMID: 21187336 PMCID: PMC3010057 DOI: 10.1085/jgp.201010468] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We describe rapid massive endocytosis (MEND) of >50% of the plasmalemma in baby hamster kidney (BHK) and HEK293 cells in response to large Ca transients. Constitutively expressed Na/Ca exchangers (NCX1) are used to generate Ca transients, whereas capacitance recording and a membrane tracer dye, FM 4–64, are used to monitor endocytosis. With high cytoplasmic adenosine triphosphate (ATP; >5 mM), Ca influx causes exocytosis followed by MEND. Without ATP, Ca transients cause only exocytosis. MEND can then be initiated by pipette perfusion of ATP, and multiple results indicate that ATP acts via phosphatidylinositol-bis 4,5-phosphate (PIP2) synthesis: PIP2 substitutes for ATP to induce MEND. ATP-activated MEND is blocked by an inositol 5-phosphatase and by guanosine 5′-[γ-thio]triphosphate (GTPγS). Block by GTPγS is overcome by the phospholipase C inhibitor, U73122, and PIP2 induces MEND in the presence of GTPγS. MEND can occur in the absence of ATP and PIP2 when cytoplasmic free Ca is clamped to 10 µM or more by Ca-buffered solutions. ATP-independent MEND occurs within seconds during Ca transients when cytoplasmic solutions contain polyamines (e.g., spermidine) or the membrane is enriched in cholesterol. Although PIP2 and cholesterol can induce MEND minutes after Ca transients have subsided, polyamines must be present during Ca transients. MEND can reverse over minutes in an ATP-dependent fashion. It is blocked by brief β-methylcyclodextrin treatments, and tests for involvement of clathrin, dynamins, calcineurin, and actin cytoskeleton were negative. Therefore, we turned to the roles of lipids. Bacterial sphingomyelinases (SMases) cause similar MEND responses within seconds, suggesting that ceramide may be important. However, Ca-activated MEND is not blocked by reagents that inhibit SMases. MEND is abolished by the alkylating phospholipase A2 inhibitor, bromoenol lactone, whereas exocytosis remains robust, and Ca influx causes MEND in cardiac myocytes without preceding exocytosis. Thus, exocytosis is not prerequisite for MEND. From these results and two companion studies, we suggest that Ca promotes the formation of membrane domains that spontaneously vesiculate to the cytoplasmic side.
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Affiliation(s)
- Vincenzo Lariccia
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
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Rosa JM, Torregrosa-Hetland CJ, Colmena I, Gutiérrez LM, García AG, Gandía L. Calcium entry through slow-inactivating L-type calcium channels preferentially triggers endocytosis rather than exocytosis in bovine chromaffin cells. Am J Physiol Cell Physiol 2011; 301:C86-98. [PMID: 21451100 DOI: 10.1152/ajpcell.00440.2010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calcium (Ca(2+))-dependent endocytosis has been linked to preferential Ca(2+) entry through the L-type (α(1D), Ca(V)1.3) of voltage-dependent Ca(2+) channels (VDCCs). Considering that the Ca(2+)-dependent exocytotic release of neurotransmitters is mostly triggered by Ca(2+) entry through N-(α(1B), Ca(V)2.2) or PQ-VDCCs (α(1A), Ca(V)2.1) and that exocytosis and endocytosis are coupled, the supposition that the different channel subtypes are specialized to control different cell functions is attractive. Here we have explored this hypothesis in primary cultures of bovine adrenal chromaffin cells where PQ channels account for 50% of Ca(2+) current (I(Ca)), 30% for N channels, and 20% for L channels. We used patch-clamp and fluorescence techniques to measure the exo-endocytotic responses triggered by long depolarizing stimuli, in 1, 2, or 10 mM concentrations of extracellular Ca(2+) ([Ca(2+)](e)). Exo-endocytotic responses were little affected by ω-conotoxin GVIA (N channel blocker), whereas ω-agatoxin IVA (PQ channel blocker) caused 80% blockade of exocytosis as well as endocytosis. In contrast, nifedipine (L channel blocker) only caused 20% inhibition of exocytosis but as much as 90% inhibition of endocytosis. Conversely, FPL67146 (an activator of L VDCCs) notably augmented endocytosis. Photoreleased caged Ca(2+) caused substantially smaller endocytotic responses compared with those produced by K(+) depolarization. Using fluorescence antibodies, no colocalization between L, N, or PQ channels with clathrin was found; a 20-30% colocalization was found between dynamin and all three channel antibodies. This is incompatible with the view that L channels are coupled to the endocytotic machine. Data rather support a mechanism implying the different inactivation rates of L (slow-inactivating) and N/PQ channels (fast-inactivating). Thus a slow but more sustained Ca(2+) entry through L channels could be a requirement to trigger endocytosis efficiently, at least in bovine chromaffin cells.
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Affiliation(s)
- Juliana M Rosa
- Instituto Teófilo Hernando, IIS del Hospital Universitario de Princesa, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
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Hilgemann DW, Fine M. Mechanistic analysis of massive endocytosis in relation to functionally defined surface membrane domains. ACTA ACUST UNITED AC 2011; 137:155-72. [PMID: 21242299 PMCID: PMC3032373 DOI: 10.1085/jgp.201010470] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A large fraction of endocytosis in eukaryotic cells occurs without adaptors or dynamins. Here, we present evidence for the involvement of lipid domains in massive endocytosis (MEND) activated by both large Ca transients and amphipathic compounds in baby hamster kidney and HEK293 cells. First, we demonstrate functional coupling of the two MEND types. Ca transients can strongly facilitate detergent-activated MEND. Conversely, an amphipath with dual alkyl chains, ditridecylphthalate, is without effect in the absence of Ca transients but induces MEND to occur within seconds during Ca transients. Ca transients, like amphipaths, enhance the extraction of lipids from cells by β-cyclodextrins. Second, we demonstrate that electrical and/or optical signals generated by selected membrane probes are nearly insensitive to MEND, suggesting that those probes segregate into membrane domains that are not taken up by MEND. Triphenylphosphoniums are increasingly excluded from domains that internalize as the carbon chain length increases from 4 to 12. The small cationic membrane dye, FM 4–64, binds well to domains that internalize, whereas a closely related dye with a larger hydrophobic moiety, di-4-ANEPPDHQ (ANEPPDHQ) is excluded. Multiple carrier-type ionophores and a small amphipathic anion, niflumic acid, are also excluded. Probes with modest MEND sensitivity include the hydrophobic anion, dipicrylamine, carbonyl cyanide m-chlorophenylhydrazone, and NBD-phosphatidylethanolamine. Third, we demonstrate that large Ca transients can strongly enhance the extracellular binding of several membrane probes, monitored electrically or optically, consistent with a more disordered membrane with more amphipath-binding sites. Fluorescence shifts of ANEPPDHQ report increased disorder of the extracellular monolayer after large Ca transients, consistent with an increased propensity of the membrane to phase separate and vesiculate. Collectively, the results indicate that >50% of the outer monolayer is ordered and can be selectively internalized during MEND responses initiated by two very different cell perturbations.
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Affiliation(s)
- Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA. donald.hilgemann@-utsouthwestern.edu
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Cárdenas AM, Marengo FD. Rapid endocytosis and vesicle recycling in neuroendocrine cells. Cell Mol Neurobiol 2010; 30:1365-70. [PMID: 21046457 DOI: 10.1007/s10571-010-9579-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2010] [Accepted: 09/02/2010] [Indexed: 11/29/2022]
Abstract
Endocytosis is a crucial process for neuroendocrine cells that ensures membrane homeostasis, vesicle recycling, and hormone release reliability. Different endocytic mechanisms have been described in chromaffin cells, such as clathrin-dependent slow endocytosis and clathrin-independent rapid endocytosis. Rapid endocytosis, classically measured in terms of a fast decrease in membrane capacitance, exhibits two different forms, "rapid compensatory endocytosis" and "excess retrieval." While excess retrieval seems to be associated with formation of long-lasting endosomes, rapid compensatory endocytosis is well correlated with exocytotic activity, and it is regarded as a mechanism associated to rapid vesicle recycling during normal secretory activity. It has been suggested that rapid compensatory endocytosis may be related to the prevalence of a transient fusion mode of exo-endocytosis. In the latter mode, the fusion pore, a nanometric-sized channel formed at the onset of exocytosis, remains open for a few hundred milliseconds and later abruptly closes, releasing a small amount of transmitters. By this mechanism, endocrine cell selectively releases low molecular weight transmitters, and rapidly recycles the secretory vesicles. In this article, we discuss the cellular and molecular mechanisms that define the different forms of exocytosis and endocytosis and their impact on vesicle recycling pathways.
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Affiliation(s)
- Ana María Cárdenas
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaiso, Chile
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Zhao Y, Fang Q, Straub SG, Lindau M, Sharp GWG. Hormonal inhibition of endocytosis: novel roles for noradrenaline and G protein G(z). J Physiol 2010; 588:3499-509. [PMID: 20643775 DOI: 10.1113/jphysiol.2010.190116] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The modulation of endocytosis following exocytosis by noradrenaline (NA), a physiological inhibitor of insulin secretion, was investigated in INS 832/13 cells using patch-clamp capacitance measurements. Endocytosis was inhibited by NA in a pertussis toxin-insensitive manner. Dialysing a synthetic peptide mimicking the C-terminus of the α-subunit of G(z) into the cells blocked the inhibition of endocytosis by NA. Cell-attached capacitance measurements indicated that inhibition by NA was due to a decreased number of endocytotic events without a change in vesicle size. Analysis of fission pore closure kinetics revealed two distinct fission modes, with NA selectively inhibiting the rapid fission pore closure events. Comparison of the actions of NA and deltamethrin, a calcineurin antagonist and potent inhibitor of endocytosis, demonstrated that they inhibit endocytosis by different mechanisms. These findings establish novel actions for NA and G(z) in insulin-secreting cells and possibly other cell types.
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Affiliation(s)
- Ying Zhao
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853-6401, USA
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Akbergenova Y, Bykhovskaia M. Synapsin regulates vesicle organization and activity-dependent recycling at Drosophila motor boutons. Neuroscience 2010; 170:441-52. [PMID: 20638447 DOI: 10.1016/j.neuroscience.2010.07.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 07/08/2010] [Accepted: 07/12/2010] [Indexed: 11/28/2022]
Abstract
Synapsin is a phosphoprotein reversibly associated with synaptic vesicles. We investigated synapsin function in mediating synaptic activity during intense stimulation at Drosophila motor boutons. Electron microscopy analysis of synapsin(-) boutons demonstrated that synapsin maintains vesicle clustering over the periphery of the bouton. Cyclosporin A pretreatment disrupted peripheral vesicle clustering, presumably due to increasing synapsin phosphorylated state. Labeling recycling vesicles with a fluorescent dye FM1-43 followed by photoconversion of the dye into electron dense product demonstrated that synapsin deficiency does not affect mixing of the reserve and recycling vesicle pools but selectively reduces the size of the reserve pool. Intense stimulation produced a significant increase in vesicle abundance and vesicle redistribution toward the central core of synapsin (+) boutons, while in synapsin (-) boutons the area occupied by vesicles did not change and the increase in vesicle numbers was not as prominent. However, intense stimulation produced an increase in basal release at synapsin(-) but not in synapsin(+) boutons, suggesting that synapsin may direct vesicles to the reserve pool. Finally, synapsin deficiency inhibited an increase in quantal size and formation of endosome-like cisternae, which was activated either by intense electrical stimulation or by high K(+) application. Taken together, these results elucidate a novel synapsin function, specifically, promoting vesicle reuptake and reserve pool formation upon intense stimulation.
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Affiliation(s)
- Y Akbergenova
- Lehigh University, Department of Biological Sciences, Bethlehem, PA 18015, USA
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42
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Developmental shift to a mechanism of synaptic vesicle endocytosis requiring nanodomain Ca2+. Nat Neurosci 2010; 13:838-44. [PMID: 20562869 DOI: 10.1038/nn.2576] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 05/12/2010] [Indexed: 11/08/2022]
Abstract
Ca(2+) is thought to be essential for the exocytosis and endocytosis of synaptic vesicles. However, the manner in which Ca(2+) coordinates these processes remains unclear, particularly at mature synapses. Using membrane capacitance measurements from calyx of Held nerve terminals in rats, we found that vesicle endocytosis is initiated primarily in Ca(2+) nanodomains around Ca(2+) channels, where exocytosis is triggered. Bulk Ca(2+) outside of the domain could also be involved in endocytosis at immature synapses, although only after extensive exocytosis at more mature synapses. This bulk Ca(2+)-dependent endocytosis required calmodulin and calcineurin activation at immature synapses, but not at more mature synapses. Similarly, GTP-independent endocytosis, which occurred after extensive exocytosis at immature synapses, became negligible after maturation. We propose that nanodomain Ca(2+) simultaneously triggers exocytosis and endocytosis of synaptic vesicles and that the molecular mechanisms underlying Ca(2+)-dependent endocytosis undergo major developmental changes at this fast central synapse.
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Khandelwal P, Ruiz WG, Apodaca G. Compensatory endocytosis in bladder umbrella cells occurs through an integrin-regulated and RhoA- and dynamin-dependent pathway. EMBO J 2010; 29:1961-75. [PMID: 20461056 PMCID: PMC2892371 DOI: 10.1038/emboj.2010.91] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Accepted: 04/20/2010] [Indexed: 11/09/2022] Open
Abstract
Compensatory endocytosis (CE) ensures recycling of membrane components and maintenance of plasma membrane size; however, the mechanisms, regulation, and physiological functions of clathrin-independent modes of CE are poorly understood. CE was studied in umbrella cells, which undergo regulated exocytosis of subapical discoidal/fusiform vesicles (DFV) during bladder filling, and may then replenish the pool of DFV by internalizing apical membrane during voiding. We found that voiding-stimulated CE, which depended on beta(1) integrin-associated signalling pathways, occurred by a dynamin-, actin-, and RhoA-regulated mechanism and was independent of caveolins, clathrin, and flotillin. Internalized apical membrane and fluid were initially found in ZO-1-positive vesicles, which were distinct from DFV, classical early endosomes, or the Golgi, and subsequently in lysosomes. We conclude that clathrin-independent CE in umbrella cells functions to recover membrane during voiding, is integrin regulated, occurs by a RhoA- and dynamin-dependent pathway, and terminates in degradation and not recapture of membrane in DFV.
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Affiliation(s)
- Puneet Khandelwal
- Department of Medicine, Laboratory of Epithelial Cell Biology and Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, PA, USA
| | - Wily G Ruiz
- Department of Medicine, Laboratory of Epithelial Cell Biology and Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, PA, USA
| | - Gerard Apodaca
- Department of Medicine, Laboratory of Epithelial Cell Biology and Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, PA, USA
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Ca2+ entry through a non-selective cation channel in Aplysia bag cell neurons. Neuroscience 2009; 162:1023-38. [DOI: 10.1016/j.neuroscience.2009.05.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 05/03/2009] [Accepted: 05/05/2009] [Indexed: 11/20/2022]
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Tsai CC, Lin CL, Wang TL, Chou AC, Chou MY, Lee CH, Peng IW, Liao JH, Chen YT, Pan CY. Dynasore inhibits rapid endocytosis in bovine chromaffin cells. Am J Physiol Cell Physiol 2009; 297:C397-406. [DOI: 10.1152/ajpcell.00562.2008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vesicle recycling is vital for maintaining membrane homeostasis and neurotransmitter release. Multiple pathways for retrieving vesicles fused to the plasma membrane have been reported in neuroendocrine cells. Dynasore, a dynamin GTPase inhibitor, has been shown to specifically inhibit endocytosis and vesicle recycling in nerve terminals. To characterize its effects in modulating vesicle recycling and repetitive exocytosis, changes in the whole cell membrane capacitance of bovine chromaffin cells were recorded in the perforated-patch configuration. Constitutive endocytosis was blocked by dynasore treatment, as shown by an increase in membrane capacitance. The membrane capacitance was increased during strong depolarizations and declined within 30 s to a value lower than the prestimulus level. The amplitude, but not the time constant, of the rapid exponential decay was significantly decreased by dynasore treatment. Although the maximal increase in capacitance induced by stimulation was significantly increased by dynasore treatment, the intercepts at time 0 of the curve fitted to the decay phase were all ∼110% of the membrane capacitance before stimulation, regardless of the dynasore concentration used. Membrane depolarization caused clathrin aggregation and F-actin continuity disruption at the cell boundary, whereas dynasore treatment induced clathrin aggregation without affecting F-actin continuity. The number of invagination pits on the surface of the plasma membrane determined using atomic force microscopy was increased and the pore was wider in dynasore-treated cells. Our data indicate that dynamin-mediated endocytosis is the main pathway responsible for rapid compensatory endocytosis.
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Akbergenova Y, Bykhovskaia M. Stimulation-induced formation of the reserve pool of vesicles in Drosophila motor boutons. J Neurophysiol 2009; 101:2423-33. [PMID: 19279147 DOI: 10.1152/jn.91122.2008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We combined electron microscopy (EM), synaptic vesicle staining by fluorescent marker FM1-43, photoconversion of the dye into an electron dense product, and electrical recordings of synaptic responses to study the distribution of reserve and recycling vesicles and its dependence on stimulation in Drosophila motor boutons. We showed that, at rest, vesicles are distributed over the periphery of the bouton, with the recycling and reserve pools being intermixed and the central core of the bouton being devoid of vesicles. Continuous high-frequency stimulation followed by a resting period mobilized the reserve vesicles into the recycling pool and, most notably, produced an increase in vesicle abundance. Recordings of synaptic activity from the temperature-sensitive endocytosis mutant shibire during continuous stimulation until complete depression provided an independent estimate of the increase in vesicle abundance on intense stimulation. EM analysis demonstrated that continuous stimulation produced an increase in the vesicle density, whereas during a subsequent resting period, vesicles filled empty areas of the bouton, spreading toward its central core. Although the observed structural potentiation did not alter basal transmitter release, it produced an increased synaptic enhancement during high-frequency stimulation. The latter effect was not observed when the boutons were potentiated using high-frequency stimulation without a subsequent resting period. We concluded therefore that the newly formed vesicles replenish the reserve pool during a resting period following intense stimulation.
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Affiliation(s)
- Yulia Akbergenova
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Pui-ock S, Ruchirawat M, Gascoyne P. Dielectrophoretic field-flow fractionation system for detection of aquatic toxicants. Anal Chem 2008; 80:7727-34. [PMID: 18788754 PMCID: PMC2726257 DOI: 10.1021/ac801095p] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Dielectrophoretic field-flow fractionation (dFFF) was applied as a contact-free way to sense changes in the plasma membrane capacitances and conductivities of cultured human HL-60 cells in response to toxicant exposure. A micropatterned electrode imposed electric forces on cells in suspension in a parabolic flow profile as they moved through a thin chamber. Relative changes in the dFFF peak elution time, reflecting changes in cell membrane area and ion permeability, were measured as indices of response during the first 150 min of exposure to eight toxicants having different single or mixed modes of action (acrylonitrile, actinomycin D, carbon tetrachloride, endosulfan, N-nitroso- N-methylurea (NMU), paraquat dichloride, puromycin, and styrene oxide). The dFFF method was compared with the cell viability assay for all toxicants and with the mitochondrial potentiometric dye assay or DNA alkaline comet assay according to the mode of action of the specific agents. Except for low doses of nucleic acid-targeting agents (actinomycin D and NMU), the dFFF method detected all toxicants more sensitively than other assays, in some cases up to 10 (5) times more sensitively than the viability approach. The results suggest the dFFF method merits additional study for possible applicability in toxicology.
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Affiliation(s)
- Sittisak Pui-ock
- Laboratory of Environmental Toxicology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Mathuros Ruchirawat
- Laboratory of Environmental Toxicology, Chulabhorn Research Institute, Bangkok, Thailand
- Department of Pharmacology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Peter Gascoyne
- Department of Molecular Pathology, M.D. Anderson Cancer Center, University of Texas, Houston, Texas 77030
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de Diego AMG, Arnáiz-Cot JJ, Hernández-Guijo JM, Gandía L, García AG. Differential variations in Ca2+ entry, cytosolic Ca2+ and membrane capacitance upon steady or action potential depolarizing stimulation of bovine chromaffin cells. Acta Physiol (Oxf) 2008; 194:97-109. [PMID: 18485124 DOI: 10.1111/j.1748-1716.2008.01871.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS This study looks into the physiology of the exocytosis of catecholamines released by adrenal medullary chromaffin cells. We have comparatively explored the exocytotic responses elicited by two different patterns of depolarizing stimulation: the widely employed square depolarizing pulses (DPs) and trains of acetylcholine-like action potentials (APs), likely the physiological mode of stimulation in the intact innervated adrenal medulla. APs were applied at 30 Hz, a frequency similar to that produced in a stressful situation. METHODS Patch-clamp, cell membrane capacitance, single cell amperometry and fluorescence were the techniques used. The variations of calcium entry measured as the integral of the calcium current, cytosolic calcium (measured with the calcium-sensitive fluorescent probe fluo-4) and exo-endocytosis (membrane capacitance variations) were the parameters measured. RESULTS Trains of AP depolarizations produced distinct responses compared to those of square depolarizations: (1) Calcium current amplitude decreased to a lesser extent along the AP train; (2) calcium entry and capacitance increments raised linearly with stimulation time whereas they deviated from linearity when square depolarizations were used; (3) slower activation and faster delayed decay phase of cytosolic calcium transients; (4) capacitance increments varied linearly with calcium entry with APs and deviated from linearity with longer depolarizations; (5) little endocytosis after stimulation with longer trains of APs and pronounced endocytosis with longer square depolarizations. CONCLUSIONS Stimulation of chromaffin cells with trains of APs produced patterns of cytosolic calcium transients, exocytotic and endocytotic responses quite different from those elicited by the widely employed DPs. Our study is relevant from the methodological and physiological points of view.
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Affiliation(s)
- A M G de Diego
- Facultad de Medicina, Instituto Teófilo Hernando, Universidad Autónoma de Madrid, Madrid, Spain.
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Weng A, Bachran C, Fuchs H, Melzig MF. Soapwort saponins trigger clathrin-mediated endocytosis of saporin, a type I ribosome-inactivating protein. Chem Biol Interact 2008; 176:204-11. [PMID: 18775419 DOI: 10.1016/j.cbi.2008.08.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Revised: 08/07/2008] [Accepted: 08/07/2008] [Indexed: 11/19/2022]
Abstract
Saporin, a type I ribosome-inactivating protein (RIP), removes adenine residues from the 28S ribosomal RNA as part of a process that leads to inhibition of protein synthesis. However, as shown in this study, neither saporin nor his-tagged saporin (both 0.6-6 pM) exert toxicity on several human cell lines including H-2171, SK-N-SH, HEP-G2, MOLT-3, THP-1, HL-60 and ECV-304. Saporin and his-tagged saporin became highly cytotoxic when they were used in a combined treatment with Soapwort saponins (SA). When combined with SA (2-4 microg/ml) saporin became as cytotoxic as the highly toxic type II RIP rViscumin reflected by an IC50 of 42.5x10(-12) M for saporin and 21.5x10(-12) M for rViscumin. We demonstrated that saporin was internalized via clathrin-mediated endocytosis, followed by the release into the endosomal transport system. Our results indicate that SA triggers this endocytic event rendering the otherwise cell membrane impermeable type I RIP saporin a potent cytotoxin. This effect was not cell line-specific suggesting that saporin exploits a common SA-dependent mechanism to enter cells.
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Affiliation(s)
- A Weng
- Institute of Pharmacy, Free University Berlin, D-14195 Berlin, Germany
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50
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He Z, Fan J, Kang L, Lu J, Xue Y, Xu P, Xu T, Chen L. Ca2+Triggers a Novel Clathrin-Independent but Actin-Dependent Fast Endocytosis in Pancreatic Beta Cells. Traffic 2008; 9:910-23. [DOI: 10.1111/j.1600-0854.2008.00730.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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