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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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Studies of the Secretory Machinery Dynamics by Total Internal Reflection Fluorescence Microscopy in Bovine Adrenal Chromaffin Cells. Methods Mol Biol 2018. [PMID: 30317519 DOI: 10.1007/978-1-4939-8760-3_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Cultured bovine chromaffin cells have been tested as a successful neuroendocrine model to study the secretory process. Changes in the dynamics of the secretory vesicles and the exocytotic machinery microdomains could be studied in control and stimulated conditions using appropriate molecular tools such as fluorescent SNARE protein expression or fluorochrome vesicular labeling in these neuroendocrine cells. Since most of these changes occur in or near the plasma membrane, the use of the total internal reflection fluorescent microscopy (TIRFM) and the implement of particle motion analysis could be essential tools to study the structural and dynamic changes of secretory machinery related with its function in this exocytotic cell model.
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Gimenez-Molina Y, Villanueva J, Francés MDM, Viniegra S, Gutiérrez LM. Multiple Mechanisms Driving F-actin-Dependent Transport of Organelles to and From Secretory Sites in Bovine Chromaffin Cells. Front Cell Neurosci 2018; 12:344. [PMID: 30356839 PMCID: PMC6190647 DOI: 10.3389/fncel.2018.00344] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 09/18/2018] [Indexed: 01/12/2023] Open
Abstract
Neuroendocrine chromaffin cells represent an excellent model to study the molecular mechanisms associated with the exo-endocytotic cycle of neurotransmitter release. In this study, EGFP-Lifeact and confocal microscopy has been used to analyze the re-organization of the cortical F-actin cytoskeleton associated to organelle transport during secretion with unprecedented detail. In these cells secretory events accumulate in temperature-sensitive and myosin II-dependent F-actin expansions and retractions affecting specific regions of the sub-membrane space. Interestingly, not only vesicles but also mitochondria are transported toward the plasmalemma during these expansions. Simultaneously, we found F-actin cytoskeletal retraction withdraws vesicles from the sub-plasmalemmal space, forming novel empty internal spaces into which organelles can be transported. In addition to these well-coordinated, F-actin-myosin II dependent processes that drive the transport of the majority of vesicles, fast transport of chromaffin vesicles was observed, albeit less frequently, which used F-actin comet tails nucleated from the granular membrane. Thus, upon cell stimulation F-actin structures use diverse mechanisms to transport organelles to and from the membrane during the exo-endocytotic cycle taking place in specific areas of cell periphery.
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Affiliation(s)
- Yolanda Gimenez-Molina
- Instituto de Neurociencias, Centro Mixto CSIC-Universidad Miguel Hernández, San Juan de Alicante, Spain
| | - José Villanueva
- Instituto de Neurociencias, Centro Mixto CSIC-Universidad Miguel Hernández, San Juan de Alicante, Spain
| | - Maria Del Mar Francés
- Instituto de Neurociencias, Centro Mixto CSIC-Universidad Miguel Hernández, San Juan de Alicante, Spain
| | - Salvador Viniegra
- Instituto de Neurociencias, Centro Mixto CSIC-Universidad Miguel Hernández, San Juan de Alicante, Spain
| | - Luis M Gutiérrez
- Instituto de Neurociencias, Centro Mixto CSIC-Universidad Miguel Hernández, San Juan de Alicante, Spain
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Gutiérrez LM, Villanueva J. The role of F-actin in the transport and secretion of chromaffin granules: an historic perspective. Pflugers Arch 2017; 470:181-186. [PMID: 28730385 PMCID: PMC5748413 DOI: 10.1007/s00424-017-2040-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/13/2017] [Accepted: 07/14/2017] [Indexed: 12/23/2022]
Abstract
Actin is one of the most ubiquitous protein playing fundamental roles in a variety of cellular processes. Since early in the 1980s, it was evident that filamentous actin (F-actin) formed a peripheral cortical barrier that prevented vesicles to access secretory sites in chromaffin cells in culture. Later, around 2000, it was described that the F-actin structure accomplishes a dual role serving both vesicle transport and retentive purposes and undergoing dynamic transient changes during cell stimulation. The complex role of the F-actin cytoskeleton in neuroendocrine secretion was further evidenced when it has been proved to participate in the scaffold structure holding together the secretory machinery at active sites and participate in the generation of mechanical forces that drive the opening of the fusion pore, during the first decade of the present century. The complex vision of the multiple roles of F-actin in secretion we have acquired to date comes largely from studies performed on traditional 2D cultures of primary cells; however, recent evidences suggest that these may not accurately mimic the 3D in vivo environment, and thus, more work is now needed on adrenomedullary cells kept in a more “native” configuration to fully understand the role of F-actin in regulating chromaffin granule transport and secretion under physiological conditions.
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Affiliation(s)
- Luis M Gutiérrez
- Instituto de Neurociencias de Alicante, Consejo Superior de Investigaciones Científicas-Universidad Miguel Hernández, Sant Joan d'Alacant, 03550, Alicante, Spain.
| | - José Villanueva
- Instituto de Neurociencias de Alicante, Consejo Superior de Investigaciones Científicas-Universidad Miguel Hernández, Sant Joan d'Alacant, 03550, Alicante, Spain
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Meunier FA, Gutiérrez LM. Captivating New Roles of F-Actin Cortex in Exocytosis and Bulk Endocytosis in Neurosecretory Cells. Trends Neurosci 2016; 39:605-613. [DOI: 10.1016/j.tins.2016.07.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 07/01/2016] [Accepted: 07/06/2016] [Indexed: 12/01/2022]
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Villanueva J, Gimenez-Molina Y, Viniegra S, Gutiérrez LM. F-actin cytoskeleton and the fate of organelles in chromaffin cells. J Neurochem 2016; 137:860-6. [PMID: 26843469 DOI: 10.1111/jnc.13560] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 01/21/2016] [Accepted: 01/22/2016] [Indexed: 12/31/2022]
Abstract
In addition to playing a fundamental structural role, the F-actin cytoskeleton in neuroendocrine chromaffin cells has a prominent influence on governing the molecular mechanism and regulating the secretory process. Performing such roles, the F-actin network might be essential to first transport, and later locate the cellular organelles participating in the secretory cycle. Chromaffin granules are transported from the internal cytosolic regions to the cell periphery along microtubular and F-actin structures. Once in the cortical region, they are embedded in the F-actin network where these vesicles experience restrictions in motility. Similarly, mitochondria transport is affected by both microtubule and F-actin inhibitors and suffers increasing motion restrictions when they are located in the cortical region. Therefore, the F-actin cortex is a key factor in defining the existence of two populations of cortical and perinuclear granules and mitochondria which could be distinguished by their different location and mobility. Interestingly, other important organelles for controlling intracellular calcium levels, such as the endoplasmic reticulum network, present clear differences in distribution and much lower mobility than chromaffin vesicles and mitochondria. Nevertheless, both mitochondria and the endoplasmic reticulum appear to distribute in the proximity of secretory sites to fulfill a pivotal role, forming triads with calcium channels ensuring the fine tuning of the secretory response. This review presents the contributions that provide the basis for our current view regarding the influence that F-actin has on the distribution of organelles participating in the release of catecholamines in chromaffin cells, and summarizes this knowledge in simple models. In chromaffin cells, organelles such as granules and mitochondria distribute forming cortical and perinuclear populations whereas others like the ER present homogenous distributions. In the present review we discuss the role of transport systems and the existence of an F-actin cortical structure as the main factors behind the formation of organelle subpopulations in this neuroendocrine cell model. This article is part of a mini review series on Chromaffin cells (ISCCB Meeting, 2015). Cover image for this issue: doi: 10.1111/jnc.13322.
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Affiliation(s)
- José Villanueva
- Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant (Alicante), Spain
| | - Yolanda Gimenez-Molina
- Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant (Alicante), Spain
| | - Salvador Viniegra
- Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant (Alicante), Spain
| | - Luis M Gutiérrez
- Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant (Alicante), Spain
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Jackson J, Papadopulos A, Meunier FA, McCluskey A, Robinson PJ, Keating DJ. Small molecules demonstrate the role of dynamin as a bi-directional regulator of the exocytosis fusion pore and vesicle release. Mol Psychiatry 2015; 20:810-9. [PMID: 25939402 DOI: 10.1038/mp.2015.56] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 03/14/2015] [Accepted: 03/24/2015] [Indexed: 12/18/2022]
Abstract
Hormones and neurotransmitters are stored in specialised vesicles and released from excitable cells through exocytosis. During vesicle fusion with the plasma membrane, a transient fusion pore is created that enables transmitter release. The protein dynamin is known to regulate fusion pore expansion (FPE). The mechanism is unknown, but requires its oligomerisation-stimulated GTPase activity. We used a palette of small molecule dynamin modulators to reveal bi-directional regulation of FPE by dynamin and vesicle release in chromaffin cells. The dynamin inhibitors Dynole 34-2 and Dyngo 4a and the dynamin activator Ryngo 1-23 reduced or increased catecholamine released from single vesicles, respectively. Total internal reflection fluorescence (TIRF) microscopy demonstrated that dynamin stimulation with Ryngo 1-23 reduced the number of neuropeptide Y (NPY) kiss-and-run events, but not full fusion events, and slowed full fusion release kinetics. Amperometric stand-alone foot signals, representing transient kiss-and-run events, were less frequent but were of longer duration, similarly to full amperometric spikes and pre-spike foot signals. These effects are not due to alterations in vesicle size. Ryngo 1-23 action was blocked by inhibitors of actin polymerisation or myosin II. Therefore, we demonstrate using a novel pharmacological approach that dynamin not only controls FPE during exocytosis, but is a bi-directional modulator of the fusion pore that increases or decreases the amount released from a vesicle during exocytosis if it is activated or inhibited, respectively. As such, dynamin has the ability to exquisitely fine-tune transmitter release.
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Affiliation(s)
- J Jackson
- Discipline of Human Physiology, Centre for Neuroscience, Flinders University, Adelaide, Australia
| | - A Papadopulos
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - F A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - A McCluskey
- Centre for Chemical Biology and Chemistry, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales, Australia
| | - P J Robinson
- Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, Australia
| | - D J Keating
- 1] Discipline of Human Physiology, Centre for Neuroscience, Flinders University, Adelaide, Australia [2] South Australian Health and Medical Research Institute (SAHMRI), Adelaide, Australia
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Secretagogue stimulation of neurosecretory cells elicits filopodial extensions uncovering new functional release sites. J Neurosci 2014; 33:19143-53. [PMID: 24305811 DOI: 10.1523/jneurosci.2634-13.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Regulated exocytosis in neurosecretory cells relies on the timely fusion of secretory granules (SGs) with the plasma membrane. Secretagogue stimulation leads to an enlargement of the cell footprint (surface area in contact with the coverslip), an effect previously attributed to exocytic fusion of SGs with the plasma membrane. Using total internal reflection fluorescence microscopy, we reveal the formation of filopodia-like structures in bovine chromaffin and PC12 cells driving the footprint expansion, suggesting the involvement of cortical actin network remodeling in this process. Using exocytosis-incompetent PC12 cells, we demonstrate that footprint enlargement is largely independent of SG fusion, suggesting that vesicular exocytic fusion plays a relatively minor role in filopodial expansion. The footprint periphery, including filopodia, undergoes extensive F-actin remodeling, an effect abolished by the actomyosin inhibitors cytochalasin D and blebbistatin. Imaging of both Lifeact-GFP and the SG marker protein neuropeptide Y-mCherry reveals that SGs actively translocate along newly forming actin tracks before undergoing fusion. Together, these data demonstrate that neurosecretory cells regulate the number of SGs undergoing exocytosis during sustained stimulation by controlling vesicular mobilization and translocation to the plasma membrane through actin remodeling. Such remodeling facilitates the de novo formation of fusion sites.
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Villanueva J, Viniegra S, Gimenez-Molina Y, García-Martinez V, Expósito-Romero G, del Mar Frances M, García-Sancho J, Gutiérrez LM. The distribution of mitochondria and endoplasmic reticulum in relation with secretory sites in chromaffin cells. J Cell Sci 2014; 127:5105-14. [DOI: 10.1242/jcs.160242] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The distribution of mitochondria and ER in relation to exocytotic sites is relevant to understand the influence of these organelles in tuning calcium signals and secretion. Confocal images of probes tagged to mitochondria and F-actin cytoskeleton revealed the existence of two populations of mitochondria, one cortical and the other perinuclear. This mitochondrial distribution was also confirmed by using electron microscopy. In contrast, ER was sparse in the cortex and more abundant in deep cytoplasmic regions. The mitochondrial distribution may be due to organellar transport, which experiences increasing restrictions in the cell cortex. Further study of organelle distribution in relation to SNARE microdomains or the granule fusion sites revealed that 1/3 of the cortical mitochondria co-localized with exocytotic sites whereas another 1/3 located at a distance smaller than 2 vesicle diameters. ER structures were also present in the vicinity of secretory sites but at a lower density. Therefore, mitochondria and ER have a spatial distribution that suggests a specialized role in modulation of exocytosis and fits with cytosolic Ca2+ microdomains described before.
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Hissa B, Pontes B, Roma PMS, Alves AP, Rocha CD, Valverde TM, Aguiar PHN, Almeida FP, Guimarães AJ, Guatimosim C, Silva AM, Fernandes MC, Andrews NW, Viana NB, Mesquita ON, Agero U, Andrade LO. Membrane cholesterol removal changes mechanical properties of cells and induces secretion of a specific pool of lysosomes. PLoS One 2013; 8:e82988. [PMID: 24376622 PMCID: PMC3869752 DOI: 10.1371/journal.pone.0082988] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 10/29/2013] [Indexed: 11/18/2022] Open
Abstract
In a previous study we had shown that membrane cholesterol removal induced unregulated lysosomal exocytosis events leading to the depletion of lysosomes located at cell periphery. However, the mechanism by which cholesterol triggered these exocytic events had not been uncovered. In this study we investigated the importance of cholesterol in controlling mechanical properties of cells and its connection with lysosomal exocytosis. Tether extraction with optical tweezers and defocusing microscopy were used to assess cell dynamics in mouse fibroblasts. These assays showed that bending modulus and surface tension increased when cholesterol was extracted from fibroblasts plasma membrane upon incubation with MβCD, and that the membrane-cytoskeleton relaxation time increased at the beginning of MβCD treatment and decreased at the end. We also showed for the first time that the amplitude of membrane-cytoskeleton fluctuation decreased during cholesterol sequestration, showing that these cells become stiffer. These changes in membrane dynamics involved not only rearrangement of the actin cytoskeleton, but also de novo actin polymerization and stress fiber formation through Rho activation. We found that these mechanical changes observed after cholesterol sequestration were involved in triggering lysosomal exocytosis. Exocytosis occurred even in the absence of the lysosomal calcium sensor synaptotagmin VII, and was associated with actin polymerization induced by MβCD. Notably, exocytosis triggered by cholesterol removal led to the secretion of a unique population of lysosomes, different from the pool mobilized by actin depolymerizing drugs such as Latrunculin-A. These data support the existence of at least two different pools of lysosomes with different exocytosis dynamics, one of which is directly mobilized for plasma membrane fusion after cholesterol removal.
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Affiliation(s)
- Barbara Hissa
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Bruno Pontes
- LPO-COPEA, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Paula Magda S. Roma
- Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ana Paula Alves
- Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Carolina D. Rocha
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Thalita M. Valverde
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Pedro Henrique N. Aguiar
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Fernando P. Almeida
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Allan J. Guimarães
- Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Rio de Janeiro, RJ, Brazil
| | - Cristina Guatimosim
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Aristóbolo M. Silva
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Maria C. Fernandes
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Norma W. Andrews
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Nathan B. Viana
- LPO-COPEA, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Oscar N. Mesquita
- Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ubirajara Agero
- Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Luciana O. Andrade
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
- * E-mail:
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Papadopulos A, Tomatis VM, Kasula R, Meunier FA. The cortical acto-Myosin network: from diffusion barrier to functional gateway in the transport of neurosecretory vesicles to the plasma membrane. Front Endocrinol (Lausanne) 2013; 4:153. [PMID: 24155741 PMCID: PMC3800816 DOI: 10.3389/fendo.2013.00153] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 10/05/2013] [Indexed: 01/14/2023] Open
Abstract
Dysregulation of regulated exocytosis is linked to an array of pathological conditions, including neurodegenerative disorders, asthma, and diabetes. Understanding the molecular mechanisms underpinning neuroexocytosis including the processes that allow neurosecretory vesicles to access and fuse with the plasma membrane and to recycle post-fusion, is therefore critical to the design of future therapeutic drugs that will efficiently tackle these diseases. Despite considerable efforts to determine the principles of vesicular fusion, the mechanisms controlling the approach of vesicles to the plasma membrane in order to undergo tethering, docking, priming, and fusion remain poorly understood. All these steps involve the cortical actin network, a dense mesh of actin filaments localized beneath the plasma membrane. Recent work overturned the long-held belief that the cortical actin network only plays a passive constraining role in neuroexocytosis functioning as a physical barrier that partly breaks down upon entry of Ca(2+) to allow secretory vesicles to reach the plasma membrane. A multitude of new roles for the cortical actin network in regulated exocytosis have now emerged and point to highly dynamic novel functions of key myosin molecular motors. Myosins are not only believed to help bring about dynamic changes in the actin cytoskeleton, tethering and guiding vesicles to their fusion sites, but they also regulate the size and duration of the fusion pore, thereby directly contributing to the release of neurotransmitters and hormones. Here we discuss the functions of the cortical actin network, myosins, and their effectors in controlling the processes that lead to tethering, directed transport, docking, and fusion of exocytotic vesicles in regulated exocytosis.
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Affiliation(s)
- Andreas Papadopulos
- Queensland Brain Institute, The University of Queensland, St Lucia Campus, Brisbane, QLD, Australia
| | - Vanesa M. Tomatis
- Queensland Brain Institute, The University of Queensland, St Lucia Campus, Brisbane, QLD, Australia
| | - Ravikiran Kasula
- Queensland Brain Institute, The University of Queensland, St Lucia Campus, Brisbane, QLD, Australia
| | - Frederic A. Meunier
- Queensland Brain Institute, The University of Queensland, St Lucia Campus, Brisbane, QLD, Australia
- *Correspondence: Frederic A. Meunier, Queensland Brain Institute, The University of Queensland, St Lucia Campus, QBI Building #79, St Lucia, QLD 4072, Australia e-mail:
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Masi G, Mercati D, Vannuccini E, Paccagnini E, Riparbelli MG, Lupetti P, Pelicci PG, Baldari CT, Ulivieri C. p66Shc regulates vesicle-mediated secretion in mast cells by affecting F-actin dynamics. J Leukoc Biol 2013; 95:285-92. [DOI: 10.1189/jlb.0313178] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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Torregrosa-Hetland CJ, Villanueva J, Garcia-Martínez V, Expósito-Romero G, Francés MDM, Gutiérrez LM. Cortical F-actin affects the localization and dynamics of SNAP-25 membrane clusters in chromaffin cells. Int J Biochem Cell Biol 2012; 45:583-92. [PMID: 23220175 DOI: 10.1016/j.biocel.2012.11.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Revised: 10/22/2012] [Accepted: 11/28/2012] [Indexed: 10/27/2022]
Abstract
It has been proposed recently that the F-actin cytoskeleton organizes the relative disposition of the SNARE proteins and calcium channels that form part of the secretory machinery in chromaffin cells, a neurosecretory model. To test this idea, we used confocal microscopy do determine if DsRed-SNAP-25 microdomains, which define the final sites of exocytosis along with syntaxin-1, preferentially remain in contact with F-actin cortical structures labelled by lifeact-EGFP. A quantitative analysis showed that in cells over-expressing these constructs there is a preferential colocalization, rather than a random distribution of SNAP-25 patches. To analyze the possible interactions between these proteins, we designed FRET experiments and tested whether treatment with agents that affect F-actin mobility would modify SNAP-25 movement. The significant FRET efficiencies detected suggest that direct molecular interactions occur, whereas dynamic experiments using TIRFM revealed that attenuation of cortical F-actin movement clearly diminishes the mobility of SNAP-25 clusters. Taken together, these data can be explained by a model that associates components of the secretory machinery to the F-actin cortex through flexible links.
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Affiliation(s)
- Cristina J Torregrosa-Hetland
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, Sant Joan d'Alacant, Carretera Nacional 332 s/n, 03550 Alicante, Spain
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