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Gremmel T, Frelinger AL, Michelson AD. Platelet Physiology. Semin Thromb Hemost 2024. [PMID: 38653463 DOI: 10.1055/s-0044-1786387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Platelets are the smallest blood cells, numbering 150 to 350 × 109/L in healthy individuals. The ability of activated platelets to adhere to an injured vessel wall and form aggregates was first described in the 19th century. Besides their long-established roles in thrombosis and hemostasis, platelets are increasingly recognized as pivotal players in numerous other pathophysiological processes including inflammation and atherogenesis, antimicrobial host defense, and tumor growth and metastasis. Consequently, profound knowledge of platelet structure and function is becoming more important in research and in many fields of modern medicine. This review provides an overview of platelet physiology focusing particularly on the structure, granules, surface glycoproteins, and activation pathways of platelets.
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Affiliation(s)
- Thomas Gremmel
- Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
- Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria
- Institute of Cardiovascular Pharmacotherapy and Interventional Cardiology, Karl Landsteiner Society, St. Pölten, Austria
- Karl Landsteiner University of Health Sciences, Krems, Austria
- Department of Internal Medicine I, Cardiology and Intensive Care Medicine, Landesklinikum Mistelbach-Gänserndorf, Mistelbach, Austria
| | - Andrew L Frelinger
- Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
| | - Alan D Michelson
- Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
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2
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Loh YP, Xiao L, Park JJ. Trafficking of hormones and trophic factors to secretory and extracellular vesicles: a historical perspective and new hypothesis. EXTRACELLULAR VESICLES AND CIRCULATING NUCLEIC ACIDS 2023; 4:568-587. [PMID: 38435713 PMCID: PMC10906782 DOI: 10.20517/evcna.2023.34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 03/05/2024]
Abstract
It is well known that peptide hormones and neurotrophic factors are intercellular messengers that are packaged into secretory vesicles in endocrine cells and neurons and released by exocytosis upon the stimulation of the cells in a calcium-dependent manner. These secreted molecules bind to membrane receptors, which then activate signal transduction pathways to mediate various endocrine/trophic functions. Recently, there is evidence that these molecules are also in extracellular vesicles, including small extracellular vesicles (sEVs), which appear to be taken up by recipient cells. This finding raised the hypothesis that they may have functions differentiated from their classical secretory hormone/neurotrophic factor actions. In this article, the historical perspective and updated mechanisms for the sorting and packaging of hormones and neurotrophic factors into secretory vesicles and their transport in these organelles for release at the plasma membrane are reviewed. In contrast, little is known about the packaging of hormones and neurotrophic factors into extracellular vesicles. One proposal is that these molecules could be sorted at the trans-Golgi network, which then buds to form Golgi-derived vesicles that can fuse to endosomes and subsequently form intraluminal vesicles. They are then taken up by multivesicular bodies to form extracellular vesicles, which are subsequently released. Other possible mechanisms for packaging RSP proteins into sEVs are discussed. We highlight some studies in the literature that suggest the dual vesicular pathways for the release of hormones and neurotrophic factors from the cell may have some physiological significance in intercellular communication.
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Affiliation(s)
- Y. Peng Loh
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lan Xiao
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Joshua J. Park
- Scientific Review Branch, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA
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3
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Voronina S, Chvanov M, De Faveri F, Mayer U, Wileman T, Criddle D, Tepikin A. Autophagy, Acute Pancreatitis and the Metamorphoses of a Trypsinogen-Activating Organelle. Cells 2022; 11:cells11162514. [PMID: 36010591 PMCID: PMC9406838 DOI: 10.3390/cells11162514] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 08/05/2022] [Accepted: 08/08/2022] [Indexed: 01/18/2023] Open
Abstract
Recent studies have highlighted the importance of autophagy and particularly non-canonical autophagy in the development and progression of acute pancreatitis (a frequent disease with considerable morbidity and significant mortality). An important early event in the development of acute pancreatitis is the intrapancreatic activation of trypsinogen, (i.e., formation of trypsin) leading to the autodigestion of the organ. Another prominent phenomenon associated with the initiation of this disease is vacuolisation and specifically the formation of giant endocytic vacuoles in pancreatic acinar cells. These organelles develop in acinar cells exposed to several inducers of acute pancreatitis (including taurolithocholic acid and high concentrations of secretagogues cholecystokinin and acetylcholine). Notably, early trypsinogen activation occurs in the endocytic vacuoles. These trypsinogen-activating organelles undergo activation, long-distance trafficking, and non-canonical autophagy. In this review, we will discuss the role of autophagy in acute pancreatitis and particularly focus on the recently discovered LAP-like non-canonical autophagy (LNCA) of endocytic vacuoles.
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Affiliation(s)
- Svetlana Voronina
- Department of Molecular Physiology and Cell Signalling, University of Liverpool, Liverpool L69 3BX, UK
| | - Michael Chvanov
- Department of Molecular Physiology and Cell Signalling, University of Liverpool, Liverpool L69 3BX, UK
| | - Francesca De Faveri
- Department of Molecular Physiology and Cell Signalling, University of Liverpool, Liverpool L69 3BX, UK
| | - Ulrike Mayer
- Biomedical Research Centre, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
| | - Tom Wileman
- Quadram Institute Bioscience and Norwich Medical School, University of East Anglia, Norwich NR4 7UQ, UK
| | - David Criddle
- Department of Molecular Physiology and Cell Signalling, University of Liverpool, Liverpool L69 3BX, UK
| | - Alexei Tepikin
- Department of Molecular Physiology and Cell Signalling, University of Liverpool, Liverpool L69 3BX, UK
- Correspondence:
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Kang H, Bae Y, Kwon Y, Kim S, Park J. Extracellular Vesicles Generated Using Bioreactors and their Therapeutic Effect on the Acute Kidney Injury Model. Adv Healthc Mater 2022; 11:e2101606. [PMID: 34773445 DOI: 10.1002/adhm.202101606] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/09/2021] [Indexed: 01/05/2023]
Abstract
Extracellular vesicles (EVs) are nano-sized vesicles secreted by cells, having beneficial effects for various types of regenerative processes. Although EVs have shown promising effects as therapeutic agents, these effects are difficult to research due to the limitations of EV production. In this study, an EV production method based on a flat-plate bioreactor is introduced. The bioreactor produces approximately seven times more mesenchymal stem cell-derived EVs than static culture conditions. The mechanism underlying the increased production of EVs in a flat-plate bioreactor and its application to acute kidney injury is investigated. This study describes the mechanism of EV production by demonstrating the link between EV biogenesis and increased calcium ion concentration under flow conditions. EVs secreted by cells cultured in the bioreactor have therapeutic efficacy in terms of improving kidney damage, resulting in tissue regeneration in a cisplatin-induced acute kidney injury model. This method will help overcome the limitations of EV production, and the analysis of the application of EVs will increase their reliability as well as the understanding of the use of bioreactor-derived EVs as therapeutic agents.
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Affiliation(s)
- Hyejin Kang
- School of Interdisciplinary Bioscience and Bioengineering Pohang University of Science and Technology Pohang Gyeongbuk 37673 Republic of Korea
| | - Yeon‐hee Bae
- EXOSOMEplus Inc. Suwon Gyeonggi‐do 16229 Republic of Korea
| | - Yongmin Kwon
- Department of Mechanical Engineering Pohang University of Science and Technology Pohang Gyeongbuk 37673 Republic of Korea
| | - Sejoong Kim
- Department of Internal Medicine Seoul National University Bundang Hospital Pohang Gyeonggi‐do 13620 Republic of Korea
| | - Jaesung Park
- School of Interdisciplinary Bioscience and Bioengineering Pohang University of Science and Technology Pohang Gyeongbuk 37673 Republic of Korea
- Department of Mechanical Engineering Pohang University of Science and Technology Pohang Gyeongbuk 37673 Republic of Korea
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Errachid A, Nohawica M, Wyganowska-Swiatkowska M. A comprehensive review of the influence of Epigallocatechin gallate on Sjögren's syndrome associated molecular regulators of exocytosis (Review). Biomed Rep 2021; 15:95. [PMID: 34631050 PMCID: PMC8493546 DOI: 10.3892/br.2021.1471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 06/25/2021] [Indexed: 12/03/2022] Open
Abstract
Sjögren's syndrome (SS) is an autoimmune disorder that affects the salivary glands, leading to reduced secretory functions and oral and ocular dryness. The salivary glands are composed of acinar cells that are responsible for the secretion and production of secretory granules, which contain salivary components, such as amylase, mucins and immunoglobulins. This secretion process involves secretory vesicle trafficking, docking, priming and membrane fusion. A failure during any of the steps in exocytosis in the salivary glands results in the altered secretion of saliva. Soluble N-ethylmaleimide-sensitive-factor attachment protein receptors, actin, tight junctions and aquaporin 5 all serve an important role in the trafficking regulation of secretory vesicles in the secretion of saliva via exocytosis. Alterations in the expression and distribution of these selected proteins leads to salivary gland dysfunction, including SS. Several studies have demonstrated that green tea polyphenols, most notably Epigallocatechin gallate (EGCG), possess both anti-inflammatory and anti-apoptotic properties in normal human cells. Molecular, cellular and animal studies have indicated that EGCG can provide protective effects against autoimmune and inflammatory reactions in salivary glands in diseases such as SS. The aim of the present article is to provide a comprehensive and up-to-date review on the possible therapeutic interactions between EGCG and the selected molecular mechanisms associated with SS.
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Affiliation(s)
- Abdelmounaim Errachid
- Department of Dental Surgery and Periodontology, Poznan University of Medicinal Sciences, 60-812 Poznań, Greater Poland, Poland.,Earth and Life Institute, University Catholique of Louvain, B-1348 Louvain-la-Neuve, Ottignies-Louvain-la-Neuve, Belgium
| | - Michal Nohawica
- Department of Dental Surgery and Periodontology, Poznan University of Medicinal Sciences, 60-812 Poznań, Greater Poland, Poland
| | - Marzena Wyganowska-Swiatkowska
- Department of Dental Surgery and Periodontology, Poznan University of Medicinal Sciences, 60-812 Poznań, Greater Poland, Poland
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AKAP79/150 coordinates leptin-induced PKA signaling to regulate K ATP channel trafficking in pancreatic β-cells. J Biol Chem 2021; 296:100442. [PMID: 33617875 PMCID: PMC8010710 DOI: 10.1016/j.jbc.2021.100442] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/11/2021] [Accepted: 02/17/2021] [Indexed: 01/21/2023] Open
Abstract
The adipocyte hormone leptin regulates glucose homeostasis both centrally and peripherally. A key peripheral target is the pancreatic β-cell, which secretes insulin upon glucose stimulation. Leptin is known to suppress glucose-stimulated insulin secretion by promoting trafficking of KATP channels to the β-cell surface, which increases K+ conductance and causes β-cell hyperpolarization. We have previously shown that leptin-induced KATP channel trafficking requires protein kinase A (PKA)-dependent actin remodeling. However, whether PKA is a downstream effector of leptin signaling or PKA plays a permissive role is unknown. Using FRET-based reporters of PKA activity, we show that leptin increases PKA activity at the cell membrane and that this effect is dependent on N-methyl-D-aspartate receptors, CaMKKβ, and AMPK, which are known to be involved in the leptin signaling pathway. Genetic knockdown and rescue experiments reveal that the increased PKA activity upon leptin stimulation requires the membrane-targeted PKA-anchoring protein AKAP79/150, indicating that PKA activated by leptin is anchored to AKAP79/150. Interestingly, disrupting protein phosphatase 2B (PP2B) anchoring to AKAP79/150, known to elevate basal PKA signaling, leads to increased surface KATP channels even in the absence of leptin stimulation. Our findings uncover a novel role of AKAP79/150 in coordinating leptin and PKA signaling to regulate KATP channel trafficking in β-cells, hence insulin secretion. The study further advances our knowledge of the downstream signaling events that may be targeted to restore insulin secretion regulation in β-cells defective in leptin signaling, such as those from obese individuals with type 2 diabetes.
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De Faveri F, Chvanov M, Voronina S, Moore D, Pollock L, Haynes L, Awais M, Beckett AJ, Mayer U, Sutton R, Criddle DN, Prior IA, Wileman T, Tepikin AV. LAP-like non-canonical autophagy and evolution of endocytic vacuoles in pancreatic acinar cells. Autophagy 2020; 16:1314-1331. [PMID: 31651224 PMCID: PMC7469629 DOI: 10.1080/15548627.2019.1679514] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 08/30/2019] [Accepted: 10/07/2019] [Indexed: 12/20/2022] Open
Abstract
Activation of trypsinogen (formation of trypsin) inside the pancreas is an early pathological event in the development of acute pancreatitis. In our previous studies we identified the activation of trypsinogen within endocytic vacuoles (EVs), cellular organelles that appear in pancreatic acinar cells treated with the inducers of acute pancreatitis. EVs are formed as a result of aberrant compound exocytosis and subsequent internalization of post-exocytic structures. These organelles can be up to 12 μm in diameter and can be actinated (i.e. coated with F-actin). Notably, EVs can undergo intracellular rupture and fusion with the plasma membrane, providing trypsin with access to cytoplasmic and extracellular targets. Unraveling the mechanisms involved in cellular processing of EVs is an interesting cell biological challenge with potential benefits for understanding acute pancreatitis. In this study we have investigated autophagy of EVs and discovered that it involves a non-canonical LC3-conjugation mechanism, reminiscent in its properties to LC3-associated phagocytosis (LAP); in both processes LC3 was recruited to single, outer organellar membranes. Trypsinogen activation peptide was observed in approximately 55% of LC3-coated EVs indicating the relevance of the described process to the early cellular events of acute pancreatitis. We also investigated relationships between actination and non-canonical autophagy of EVs and concluded that these processes represent sequential steps in the evolution of EVs. Our study expands the known roles of LAP and indicates that, in addition to its well-established functions in phagocytosis and macropinocytosis, LAP is also involved in the processing of post-exocytic organelles in exocrine secretory cells. ABBREVIATIONS AP: acute pancreatitis; CCK: cholecystokinin; CLEM: correlative light and electron microscopy; DPI: diphenyleneiodonium; EV: endocytic vacuole; LAP: LC3-associate phagocytosis; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; PACs: pancreatic acinar cells; PFA: paraformaldehyde; PtdIns3K: phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol 3-phosphate; Res: resveratrol; TAP: trypsinogen activation peptide; TEM: transmission electron microscopy; TLC-S: taurolithocholic acid 3-sulfate; TRD: Dextran Texas Red 3000 MW Neutral; ZGs: zymogen granules.
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Affiliation(s)
- Francesca De Faveri
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | - Michael Chvanov
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | - Svetlana Voronina
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | - Danielle Moore
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | - Liam Pollock
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | - Lee Haynes
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | - Muhammad Awais
- Department of Molecular and Clinical Cancer Medicine, University of Liverpool, Liverpool, UK
| | - Alison J. Beckett
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | - Ulrike Mayer
- Bio-Medical Research Centre, Norwich Medical School, Faculty of Medicine and Health Sciences, University of East Anglia, Norwich, UK
| | - Robert Sutton
- Department of Molecular and Clinical Cancer Medicine, University of Liverpool, Liverpool, UK
| | - David N. Criddle
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | - Ian A. Prior
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | - Tom Wileman
- Bio-Medical Research Centre, Norwich Medical School, Faculty of Medicine and Health Sciences, University of East Anglia, Norwich, UK
| | - Alexei V. Tepikin
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
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Ma W, Chang J, Tong J, Ho U, Yau B, Kebede MA, Thorn P. Arp2/3 nucleates F-actin coating of fusing insulin granules in pancreatic β cells to control insulin secretion. J Cell Sci 2020; 133:jcs236794. [PMID: 32079655 DOI: 10.1242/jcs.236794] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 02/05/2020] [Indexed: 01/11/2023] Open
Abstract
F-actin dynamics are known to control insulin secretion, but the point of intersection with the stimulus-secretion cascade is unknown. Here, using multiphoton imaging of β cells isolated from Lifeact-GFP transgenic mice, we show that glucose stimulation does not cause global changes in subcortical F-actin. Instead, we observe spatially discrete and transient F-actin changes around each fusing granule. This F-actin remodelling is dependent on actin nucleation and is observed for granule fusion induced by either glucose or high potassium stimulation. Using GFP-labelled proteins, we identify local enrichment of Arp3, dynamin 2 and clathrin, all occurring after granule fusion, suggesting early recruitment of an endocytic complex to the fusing granules. Block of Arp2/3 activity with drugs or shRNA inhibits F-actin coating, traps granules at the cell membrane and reduces insulin secretion. Block of formin-mediated actin nucleation also blocks F-actin coating, but has no effect on insulin secretion. We conclude that local Arp2/3-dependent actin nucleation at the sites of granule fusion plays an important role in post-fusion granule dynamics and in the regulation of insulin secretion.
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Affiliation(s)
- Wei Ma
- Discipline of Physiology, School of Medical Sciences, Charles Perkins Centre, University of Sydney, Camperdown 2006, Australia
| | - Jenny Chang
- School of Biomedical Sciences, University of Queensland, St Lucia 4072, Australia
| | - Jason Tong
- Discipline of Physiology, School of Medical Sciences, Charles Perkins Centre, University of Sydney, Camperdown 2006, Australia
| | - Uda Ho
- School of Biomedical Sciences, University of Queensland, St Lucia 4072, Australia
| | - Belinda Yau
- Discipline of Physiology, School of Medical Sciences, Charles Perkins Centre, University of Sydney, Camperdown 2006, Australia
| | - Melkam A Kebede
- Discipline of Physiology, School of Medical Sciences, Charles Perkins Centre, University of Sydney, Camperdown 2006, Australia
| | - Peter Thorn
- Discipline of Physiology, School of Medical Sciences, Charles Perkins Centre, University of Sydney, Camperdown 2006, Australia
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Galkina SI, Fedorova NV, Golenkina EA, Stadnichuk VI, Sud’ina GF. Cytonemes Versus Neutrophil Extracellular Traps in the Fight of Neutrophils with Microbes. Int J Mol Sci 2020; 21:ijms21020586. [PMID: 31963289 PMCID: PMC7014225 DOI: 10.3390/ijms21020586] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 12/11/2022] Open
Abstract
Neutrophils can phagocytose microorganisms and destroy them intracellularly using special bactericides located in intracellular granules. Recent evidence suggests that neutrophils can catch and kill pathogens extracellularly using the same bactericidal agents. For this, live neutrophils create a cytoneme network, and dead neutrophils provide chromatin and proteins to form neutrophil extracellular traps (NETs). Cytonemes are filamentous tubulovesicular secretory protrusions of living neutrophils with intact nuclei. Granular bactericides are localized in membrane vesicles and tubules of which cytonemes are composed. NETs are strands of decondensed DNA associated with histones released by died neutrophils. In NETs, bactericidal neutrophilic agents are adsorbed onto DNA strands and are not covered with a membrane. Cytonemes and NETs occupy different places in protecting the body against infections. Cytonemes can develop within a few minutes at the site of infection through the action of nitric oxide or actin-depolymerizing alkaloids of invading microbes. The formation of NET in vitro occurs due to chromatin decondensation resulting from prolonged activation of neutrophils with PMA (phorbol 12-myristate 13-acetate) or other stimuli, or in vivo due to citrullination of histones with peptidylarginine deiminase 4. In addition to antibacterial activity, cytonemes are involved in cell adhesion and communications. NETs play a role in autoimmunity and thrombosis.
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Affiliation(s)
- Svetlana I. Galkina
- Lomonosov Moscow State University, A. N. Belozersky Institute of Physico-Chemical Biology, 119991 Moscow, Russia; (N.V.F.); (E.A.G.)
- Correspondence: (S.I.G.); (G.F.S.); Tel.: +7-495-939-5408 (S.I.G.)
| | - Natalia V. Fedorova
- Lomonosov Moscow State University, A. N. Belozersky Institute of Physico-Chemical Biology, 119991 Moscow, Russia; (N.V.F.); (E.A.G.)
| | - Ekaterina A. Golenkina
- Lomonosov Moscow State University, A. N. Belozersky Institute of Physico-Chemical Biology, 119991 Moscow, Russia; (N.V.F.); (E.A.G.)
| | | | - Galina F. Sud’ina
- Lomonosov Moscow State University, A. N. Belozersky Institute of Physico-Chemical Biology, 119991 Moscow, Russia; (N.V.F.); (E.A.G.)
- Correspondence: (S.I.G.); (G.F.S.); Tel.: +7-495-939-5408 (S.I.G.)
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Couto NF, Rezende L, Fernandes-Braga W, Alves AP, Agero U, Alvarez-Leite J, Damasceno NRT, Castro-Gomes T, Andrade LO. OxLDL alterations in endothelial cell membrane dynamics leads to changes in vesicle trafficking and increases cell susceptibility to injury. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183139. [PMID: 31812625 DOI: 10.1016/j.bbamem.2019.183139] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 11/14/2019] [Accepted: 11/27/2019] [Indexed: 02/07/2023]
Abstract
Plasma membrane repair (PMR) is an important process for cell homeostasis, especially for cells under constant physical stress. Repair involves a sequence of Ca2+-dependent events, including lysosomal exocytosis and subsequent compensatory endocytosis. Cholesterol sequestration from plasma membrane causes actin cytoskeleton reorganization and polymerization, increasing cell stiffness, which leads to exocytosis and reduction of a peripheral pool of lysosomes involved in PMR. These changes in mechanical properties are similar to those observed in cells exposed to oxidized Low Density Lipoprotein (oxLDL), a key molecule during atherosclerosis development. Using a human umbilical vein endothelial cell line (EAhY926) we evaluated the influence of mechanical modulation induced by oxLDL in PMR and its effect in endothelial fragility. Similar to MβCD (a drug capable of sequestering cholesterol) treatment, oxLDL exposure led to actin reorganization and de novo polymerization, as well as an increase in cell rigidity and lysosomal exocytosis. Additionally, for both MβCD and oxLDL treated cells, there was an initial increase in endocytic events, likely triggered by the peak of exocytosis induced by both treatments. However, no further endocytic events were observed, suggesting that constitutive endocytosis is blocked upon treatment and that the reorganized cytoskeleton function as a mechanical barrier to membrane traffic. Finally, the increase in cell rigidity renders cells more prone to mechanical injury. Together, these data show that mechanical modulation induced by oxLDL exposure not only alters membrane traffic in cells, but also makes them more susceptible to mechanical injury, which may likely contribute to the initial steps of atherosclerosis development.
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Affiliation(s)
- Natália Fernanda Couto
- Department of Morphology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Luisa Rezende
- Department of Morphology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Weslley Fernandes-Braga
- Department of Biochemistry and Immunology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ana Paula Alves
- Department of Physics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ubirajara Agero
- Department of Physics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Jacqueline Alvarez-Leite
- Department of Biochemistry and Immunology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | | | - Thiago Castro-Gomes
- Department of Parasitology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Luciana O Andrade
- Department of Morphology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
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Deng H, Dutta P, Liu J. Stochastic modeling of nanoparticle internalization and expulsion through receptor-mediated transcytosis. NANOSCALE 2019; 11:11227-11235. [PMID: 31157808 PMCID: PMC6634982 DOI: 10.1039/c9nr02710f] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Receptor-mediated transcytosis (RMT) is a fundamental mechanism for the transcellular transport of nanoparticles. RMT is a complex process, during which the nanoparticles actively interact with the membrane and the membrane profile undergoes extreme deformations for particle internalization and expulsion. In this work, we developed a stochastic model to study the endocytosis and exocytosis of nanoparticles across soft membranes. The model is based on the combination of a stochastic particle binding model with a membrane model, and accounts for both clathrin-mediated endocytosis for internalization and actin-mediated exocytosis for expulsion. Our results showed that nanoparticles must have certain avidity with enough ligand density and ligand-receptor binding affinity to be taken up, while too high avidity limited the particle release from the cell surface. We further explored the functional roles of actin during exocytosis, which has been a topic under active debate. Our simulations indicated that the membrane compression due to the actin induced tension tended to break the ligand-receptor bonds and to shrink the fusion pore. Therefore, an intermediate tension promoted the fusion pore expansion and nanoparticle release, while high tension prohibits particle release. Our model provides new and critical mechanistic insights into RMT, and represents a powerful platform for aiding the rational design of nanocarriers for controlled drug delivery.
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Affiliation(s)
- Hua Deng
- School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99163, USA.
| | - Prashanta Dutta
- School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99163, USA.
| | - Jin Liu
- School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99163, USA.
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de Oliveira C, Khatua B, Bag A, El-Kurdi B, Patel K, Mishra V, Navina S, Singh VP. Multimodal Transgastric Local Pancreatic Hypothermia Reduces Severity of Acute Pancreatitis in Rats and Increases Survival. Gastroenterology 2019; 156:735-747.e10. [PMID: 30518512 PMCID: PMC6368865 DOI: 10.1053/j.gastro.2018.10.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 10/11/2018] [Accepted: 10/20/2018] [Indexed: 12/16/2022]
Abstract
BACKGROUND & AIMS Acute pancreatitis (AP) of different etiologies is associated with the activation of different signaling pathways in pancreatic cells, posing challenges to the development of targeted therapies. We investigated whether local pancreatic hypothermia, without systemic hypothermia, could lessen the severity of AP induced by different methods in rats. METHODS A urethane balloon with 2 polyurethane tubes was placed inside the stomach of rats. AP was induced in Wistar rats by the administration of cerulein or glyceryl tri-linoleate (GTL). Then, cold water was infused into the balloon to cool the pancreas. Pancreatic temperatures were selected based on those found to decrease acinar cell injury. An un-perfused balloon was used as a control. Pancreatic and rectal temperatures were monitored, and an infrared lamp or heating pad was used to avoid generalized hypothermia. We collected blood, pancreas, kidney, and lung tissues and analyzed them by histology, immunofluorescence, immunoblot, cytokine and chemokine magnetic bead, and DNA damage assays. The effect of hypothermia on signaling pathways initiated by cerulein and GTL was studied in acinar cells. RESULTS Rats with pancreatic cooling developed less severe GTL-induced AP compared with rats that received the control balloon. In acinar cells, cooling decreased the lipolysis induced by GTL, increased the micellar form of its fatty acid, lowered the increase in cytosolic calcium, prevented the loss of mitochondrial membrane potential (by 70%-80%), and resulted in a 40%-50% decrease in the uptake of a fatty acid tracer. In rats with AP, cooling decreased pancreatic necrosis by 48%, decreased serum levels of cytokines and markers of cell damage, and decreased markers of lung and renal damage. Pancreatic cooling increased the proportions of rats surviving 6 hours after induction of AP (to 90%, from <10% of rats that received the control balloon). In rats with cerulein-induced AP, pancreatic cooling decreased pancreatic markers of apoptosis and inflammation. CONCLUSIONS In rats with AP, transgastric local pancreatic hypothermia decreases pancreatic necrosis, apoptosis, inflammation, and markers of pancreatitis severity and increases survival.
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Affiliation(s)
- Cristiane de Oliveira
- Department of Medicine, Mayo Clinic, Scottsdale, AZ, University of Pittsburgh, Pittsburgh, PA
| | - Biswajit Khatua
- Department of Medicine, Mayo Clinic, Scottsdale, AZ, University of Pittsburgh, Pittsburgh, PA
| | - Arup Bag
- Department of Medicine, Mayo Clinic, Scottsdale, AZ, University of Pittsburgh, Pittsburgh, PA
| | - Bara El-Kurdi
- Department of Medicine, Mayo Clinic, Scottsdale, AZ, University of Pittsburgh, Pittsburgh, PA
| | - Krutika Patel
- Department of Medicine, Mayo Clinic, Scottsdale, AZ, University of Pittsburgh, Pittsburgh, PA
| | - Vivek Mishra
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Sarah Navina
- Pathology, University of Pittsburgh, Pittsburgh, PA
| | - Vijay P. Singh
- Department of Medicine, Mayo Clinic, Scottsdale, AZ, University of Pittsburgh, Pittsburgh, PA
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14
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The C Terminus of Rotavirus VP4 Protein Contains an Actin Binding Domain Which Requires Cooperation with the Coiled-Coil Domain for Actin Remodeling. J Virol 2018; 93:JVI.01598-18. [PMID: 30333172 DOI: 10.1128/jvi.01598-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 10/10/2018] [Indexed: 12/28/2022] Open
Abstract
The interactions between viruses and actin cytoskeleton have been widely studied. We showed that rotaviruses remodel microfilaments in intestinal cells and demonstrated that this was due to the VP4 spike protein. Microfilaments mainly occur in the apical domain of infected polarized enterocytes and favor the polarized apical exit of viral progeny. The present work aims at the identification of molecular determinants of actin-VP4 interactions. We used various deletion mutants of VP4 that were transfected into Cos-7 cells and analyzed interactions by immunofluorescence confocal microscopy. It has been established that the C-terminal part of VP4 is embedded within viral particles when rotavirus assembles. The use of specific monoclonal antibodies demonstrated that VP4 is expressed in different forms in infected cells: classically as spike on the outer layer of virus particles, but also as free soluble protein in the cytosol. The C terminus of free VP4 was identified as interacting with actin microfilaments. The VP4 actin binding domain is unable to promote microfilament remodeling by itself; the coiled-coil domain is also required in this process. This actin-binding domain was shown to dominate a previously identified peroxisomal targeting signal, located in the three last amino acids of VP4. The newly identified actin-binding domain is highly conserved in rotavirus strains from species A, B, and C, suggesting that actin binding and remodeling is a general strategy for rotavirus exit. This provides a novel mechanism of protein-protein interactions, not involving cell signaling pathways, to facilitate rotavirus exit.IMPORTANCE Rotaviruses are causal agents of acute infantile viral diarrhea. In intestinal cells, in vitro as well as in vivo, virus assembly and exit do not imply cell lysis but rely on an active process in which the cytoskeleton plays a major role. We describe here a novel molecular mechanism by which the rotavirus spike protein VP4 drives actin remodeling. This relies on the fact that VP4 occurs in different forms. Besides its structural function within the virion, a large proportion of VP4 is expressed as free protein. Here, we show that free VP4 possesses a functional actin-binding domain. This domain, in coordination with a coiled-coil domain, promotes actin cytoskeleton remodeling, thereby providing the capacity to destabilize the cell membrane and allow efficient rotavirus exit.
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Romarowski A, Velasco Félix ÁG, Torres Rodríguez P, Gervasi MG, Xu X, Luque GM, Contreras-Jiménez G, Sánchez-Cárdenas C, Ramírez-Gómez HV, Krapf D, Visconti PE, Krapf D, Guerrero A, Darszon A, Buffone MG. Super-resolution imaging of live sperm reveals dynamic changes of the actin cytoskeleton during acrosomal exocytosis. J Cell Sci 2018; 131:jcs.218958. [PMID: 30301778 DOI: 10.1242/jcs.218958] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 09/25/2018] [Indexed: 01/14/2023] Open
Abstract
Filamentous actin (F-actin) is a key factor in exocytosis in many cell types. In mammalian sperm, acrosomal exocytosis (denoted the acrosome reaction or AR), a special type of controlled secretion, is regulated by multiple signaling pathways and the actin cytoskeleton. However, the dynamic changes of the actin cytoskeleton in live sperm are largely not understood. Here, we used the powerful properties of SiR-actin to examine actin dynamics in live mouse sperm at the onset of the AR. By using a combination of super-resolution microscopy techniques to image sperm loaded with SiR-actin or sperm from transgenic mice containing Lifeact-EGFP, six regions containing F-actin within the sperm head were revealed. The proportion of sperm possessing these structures changed upon capacitation. By performing live-cell imaging experiments, we report that dynamic changes of F-actin during the AR occur in specific regions of the sperm head. While certain F-actin regions undergo depolymerization prior to the initiation of the AR, others remain unaltered or are lost after exocytosis occurs. Our work emphasizes the utility of live-cell nanoscopy, which will undoubtedly impact the search for mechanisms that underlie basic sperm functions.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Ana Romarowski
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1428ADN, Argentina
| | - Ángel G Velasco Félix
- Laboratorio Nacional de Microscopía Avanzada, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos 62210, México
| | - Paulina Torres Rodríguez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos 62210, México
| | - María G Gervasi
- Department of Veterinary and Animal Science, Paige Labs, University of Massachusetts, Amherst, MA 01003, USA
| | - Xinran Xu
- Department of Electrical and Computer Engineering, School of Biomedical Engineering, 1301 Campus Delivery, Fort Collins, CO 80523, USA
| | - Guillermina M Luque
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1428ADN, Argentina
| | - Gastón Contreras-Jiménez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos 62210, México
| | - Claudia Sánchez-Cárdenas
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos 62210, México
| | - Héctor V Ramírez-Gómez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos 62210, México
| | - Diego Krapf
- Department of Electrical and Computer Engineering, School of Biomedical Engineering, 1301 Campus Delivery, Fort Collins, CO 80523, USA
| | - Pablo E Visconti
- Department of Veterinary and Animal Science, Paige Labs, University of Massachusetts, Amherst, MA 01003, USA
| | - Dario Krapf
- Instituto de Biología Molecular y Celular de Rosario (CONICET-UNR), Rosario, Santa Fe S2000EZP, Argentina
| | - Adán Guerrero
- Laboratorio Nacional de Microscopía Avanzada, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos 62210, México
| | - Alberto Darszon
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos 62210, México
| | - Mariano G Buffone
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1428ADN, Argentina
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A Serine/Threonine Kinase 16-Based Phospho-Proteomics Screen Identifies WD Repeat Protein-1 As A Regulator Of Constitutive Secretion. Sci Rep 2018; 8:13049. [PMID: 30158666 PMCID: PMC6115458 DOI: 10.1038/s41598-018-31426-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 08/14/2018] [Indexed: 01/03/2023] Open
Abstract
The plasma membrane of polarized hepatocytes is functionally divided into two domains: the apical and basolateral. Our focus is to define the molecular basis of polarized protein sorting of newly-synthesized membrane and secretory proteins in WIF-B cells, an excellent model system for polarized hepatocytes. We determined that MAL2 (myelin and lymphocyte protein 2) and its binding partner, serine/threonine kinase 16 (STK16) regulate basolateral constitutive secretion. Because STK16 is a constitutively active kinase, we reasoned that constitutively phosphorylated substrates must participate in constitutive secretion. To identify either STK16 substrates or other proteins that regulate constitutive secretion, we took a proteomics approach. Post-nuclear supernatants from cells expressing wild type or a kinase-dead (E202A) STK16 were separated on 2D gels and immunoblotted with antibodies against phospho-serine/threonine residues. Sixteen spots were identified from E202A-expressing cells that reproducibly displayed decreased immunoreactivity. From these spots, 28 proteins were identified as possible STK16 substrates. Out of these 28 possible substrates, 25% of them encode predicted STK16 phosphorylation consensus sites, with WD repeat containing protein-1 (WDR1) encoding two such sites. Based on this finding and on the finding that actin remodeling is required for hepatic secretion, we further confirmed that WDR1 is a phosphoprotein that regulates secretion.
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17
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Chvanov M, De Faveri F, Moore D, Sherwood MW, Awais M, Voronina S, Sutton R, Criddle DN, Haynes L, Tepikin AV. Intracellular rupture, exocytosis and actin interaction of endocytic vacuoles in pancreatic acinar cells: initiating events in acute pancreatitis. J Physiol 2018; 596:2547-2564. [PMID: 29717784 PMCID: PMC6023832 DOI: 10.1113/jp275879] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 04/20/2018] [Indexed: 12/18/2022] Open
Abstract
Key points Giant trypsin‐containing endocytic vacuoles are formed in pancreatic acinar cells stimulated with inducers of acute pancreatitis. F‐actin envelops endocytic vacuoles and regulates their properties. Endocytic vacuoles can rupture and release their content into the cytosol of acinar cells. Endocytic vacuoles can fuse with the plasma membrane of acinar cells and exocytose their content.
Abstract Intrapancreatic activation of trypsinogen is an early event in and hallmark of the development of acute pancreatitis. Endocytic vacuoles, which form by disconnection and transport of large post‐exocytic structures, are the only resolvable sites of the trypsin activity in live pancreatic acinar cells. In the present study, we characterized the dynamics of endocytic vacuole formation induced by physiological and pathophysiological stimuli and visualized a prominent actin coat that completely or partially surrounded endocytic vacuoles. An inducer of acute pancreatitis taurolithocholic acid 3‐sulphate and supramaximal concentrations of cholecystokinin triggered the formation of giant (more than 2.5 μm in diameter) endocytic vacuoles. We discovered and characterized the intracellular rupture of endocytic vacuoles and the fusion of endocytic vacuoles with basal and apical regions of the plasma membrane. Experiments with specific protease inhibitors suggest that the rupture of endocytic vacuoles is probably not induced by trypsin or cathepsin B. Perivacuolar filamentous actin (observed on the surface of ∼30% of endocytic vacuoles) may play a stabilizing role by preventing rupture of the vacuoles and fusion of the vacuoles with the plasma membrane. The rupture and fusion of endocytic vacuoles allow trypsin to escape the confinement of a membrane‐limited organelle, gain access to intracellular and extracellular targets, and initiate autodigestion of the pancreas, comprising a crucial pathophysiological event. Giant trypsin‐containing endocytic vacuoles are formed in pancreatic acinar cells stimulated with inducers of acute pancreatitis. F‐actin envelops endocytic vacuoles and regulates their properties. Endocytic vacuoles can rupture and release their content into the cytosol of acinar cells. Endocytic vacuoles can fuse with the plasma membrane of acinar cells and exocytose their content.
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Affiliation(s)
- Michael Chvanov
- Department of Cellular and Molecular Physiology and NIHR Liverpool Pancreas Biomedical Research Unit, University of Liverpool, Liverpool, UK
| | - Francesca De Faveri
- Department of Cellular and Molecular Physiology and NIHR Liverpool Pancreas Biomedical Research Unit, University of Liverpool, Liverpool, UK
| | - Danielle Moore
- Department of Cellular and Molecular Physiology and NIHR Liverpool Pancreas Biomedical Research Unit, University of Liverpool, Liverpool, UK
| | - Mark W Sherwood
- Department of Cellular and Molecular Physiology and NIHR Liverpool Pancreas Biomedical Research Unit, University of Liverpool, Liverpool, UK
| | - Muhammad Awais
- Department of Cellular and Molecular Physiology and NIHR Liverpool Pancreas Biomedical Research Unit, University of Liverpool, Liverpool, UK
| | - Svetlana Voronina
- Department of Cellular and Molecular Physiology and NIHR Liverpool Pancreas Biomedical Research Unit, University of Liverpool, Liverpool, UK
| | - Robert Sutton
- Department of Cellular and Molecular Physiology and NIHR Liverpool Pancreas Biomedical Research Unit, University of Liverpool, Liverpool, UK
| | - David N Criddle
- Department of Cellular and Molecular Physiology and NIHR Liverpool Pancreas Biomedical Research Unit, University of Liverpool, Liverpool, UK
| | - Lee Haynes
- Department of Cellular and Molecular Physiology and NIHR Liverpool Pancreas Biomedical Research Unit, University of Liverpool, Liverpool, UK
| | - Alexei V Tepikin
- Department of Cellular and Molecular Physiology and NIHR Liverpool Pancreas Biomedical Research Unit, University of Liverpool, Liverpool, UK
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Venditti M, Fasano C, Santillo A, Aniello F, Minucci S. First evidence of DAAM1 localization in mouse seminal vesicles and its possible involvement during regulated exocytosis. C R Biol 2018; 341:228-234. [PMID: 29571963 DOI: 10.1016/j.crvi.2018.03.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 03/01/2018] [Accepted: 03/01/2018] [Indexed: 12/26/2022]
Abstract
Dishevelled-associated activator of morphogenesis 1 (DAAM1) is a protein belonging to the formin family, which regulates, together with the small GTPase RhoA, the nucleation and the assembly of actin fibres through Wnt-Dishevelled PCP pathway. Its role has been investigated in essential biological processes, such as cell polarity, movement and adhesion during morphogenesis and organogenesis. In this work, we studied the expression of DAAM1 mRNA and protein by PCR and Western blot analyses and its co-localization with actin in adult mouse seminal vesicles by immunofluorescence. We show that both proteins are cytoplasmic: actin is evident at cell-cell junctions and at cell cortex; DAAM1 had a more diffused localization, but is also prominent at the apical plasmatic membrane of epithelial cells. These findings support our hypothesis of a role of DAAM1 in cytoskeletal rearrangement that occurs during the exocytosis of secretory vesicles, and in particular concerning actin filaments. We were also able to detect DAAM1 and actin association in the smooth muscle cells that surround the epithelium too. In this case, we could only speculate the possible involvement of this formin in muscular cells in the maintenance and the regulation of the contractile structures. The present results strongly suggest that DAAM1 could have a pivotal role in vesicle exocytosis and in the physiology of mouse seminal vesicles.
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Affiliation(s)
- Massimo Venditti
- Dipartimento di Medicina Sperimentale, Sez, Fisiologia Umana e Funzioni Biologiche Integrate, Università degli studi della Campania "Luigi Vanvitelli", Via Costantinopoli, 16, 80138 Napoli, Italy
| | - Chiara Fasano
- Dipartimento di Medicina Sperimentale, Sez, Fisiologia Umana e Funzioni Biologiche Integrate, Università degli studi della Campania "Luigi Vanvitelli", Via Costantinopoli, 16, 80138 Napoli, Italy
| | - Alessandra Santillo
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania "Luigi Vanvitelli", Caserta, Italy
| | - Francesco Aniello
- Dipartimento di Biologia, Università degli Studi di Napoli "Federico II", Napoli, Italy
| | - Sergio Minucci
- Dipartimento di Medicina Sperimentale, Sez, Fisiologia Umana e Funzioni Biologiche Integrate, Università degli studi della Campania "Luigi Vanvitelli", Via Costantinopoli, 16, 80138 Napoli, Italy.
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β-adrenoceptor activation increased VAMP-2 and syntaxin-4 in secretory granules are involved in protein secretion of submandibular gland through the PKA/F-actin pathway. Biosci Rep 2018; 38:BSR20171142. [PMID: 29358308 PMCID: PMC5809613 DOI: 10.1042/bsr20171142] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 01/17/2018] [Accepted: 01/18/2018] [Indexed: 11/17/2022] Open
Abstract
Autologous submandibular gland transplantation is an effective treatment for severe dry eye syndrome. However, the protein secretion in transplanted gland is altered by a mechanism that remains to be elucidated. In the present study, we found that β1-adrenoceptor (β1-AR) and β2-AR expression and the phosphorylation of the downstream molecule protein kinase A (PKA) were elevated in transplanted submandibular glands obtained from epiphora patients. Synaptobrevin/vesicle-associated membrane protein 2 (VAMP-2) interacted with syntaxin-4 and actin in human submandibular gland. The contents of syntaxin-4 and actin interacting with VAMP-2 were increased in transplanted gland. Moreover, VAMP-2 and syntaxin-4 expression in the secretory granule fraction, and VAMP-2 expression in the membrane protein fraction were increased in isoproterenol-treated and transplanted glands. Isoproterenol increased F-actin polymerization in the apical and lateral regions of the cytoplasm in both control and transplanted glands. Inhibiting PKA activity and/or F-actin formation abolished the isoproterenol-enhanced expression of VAMP-2 and syntaxin-4 in the secretory granule fraction and the isoproterenol-enhanced expression of VAMP-2 in the membrane protein fraction. Taken together, these results indicate that the activation of β-ARs induces secretory granules and cell membrane fusion via the interaction of VAMP-2 and syntaxin-4 in a PKA- and F-actin-dependent manner in human submandibular gland. Up-regulated β-ARs might participate in altering protein secretion in transplanted submandibular gland by promoting the interaction of VAMP-2 with syntaxin-4.
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20
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Mo M, Zhou Y, Li S, Wu Y. Three-Dimensional Culture Reduces Cell Size By Increasing Vesicle Excretion. Stem Cells 2017; 36:286-292. [DOI: 10.1002/stem.2729] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 09/15/2017] [Accepted: 10/13/2017] [Indexed: 12/12/2022]
Affiliation(s)
- Miaohua Mo
- School of Life Sciences, Tsinghua University; Beijing People's Republic of China
- The Shenzhen Key Laboratory of Health Sciences and Technology, Graduate School at Shenzhen, Tsinghua University; Shenzhen People's Republic of China
| | - Ying Zhou
- School of Life Sciences, Tsinghua University; Beijing People's Republic of China
- The Shenzhen Key Laboratory of Health Sciences and Technology, Graduate School at Shenzhen, Tsinghua University; Shenzhen People's Republic of China
| | - Sen Li
- The Shenzhen Key Laboratory of Health Sciences and Technology, Graduate School at Shenzhen, Tsinghua University; Shenzhen People's Republic of China
| | - Yaojiong Wu
- The Shenzhen Key Laboratory of Health Sciences and Technology, Graduate School at Shenzhen, Tsinghua University; Shenzhen People's Republic of China
- Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University; Shenzhen People's Republic of China
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Neuronal Dysfunction in iPSC-Derived Medium Spiny Neurons from Chorea-Acanthocytosis Patients Is Reversed by Src Kinase Inhibition and F-Actin Stabilization. J Neurosci 2017; 36:12027-12043. [PMID: 27881786 DOI: 10.1523/jneurosci.0456-16.2016] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 09/07/2016] [Accepted: 09/26/2016] [Indexed: 11/21/2022] Open
Abstract
Chorea-acanthocytosis (ChAc) is a fatal neurological disorder characterized by red blood cell acanthocytes and striatal neurodegeneration. Recently, severe cell membrane disturbances based on depolymerized cortical actin and an elevated Lyn kinase activity in erythrocytes from ChAc patients were identified. How this contributes to the mechanism of neurodegeneration is still unknown. To gain insight into the pathophysiology, we established a ChAc patient-derived induced pluripotent stem cell model and an efficient differentiation protocol providing a large population of human striatal medium spiny neurons (MSNs), the main target of neurodegeneration in ChAc. Patient-derived MSNs displayed enhanced neurite outgrowth and ramification, whereas synaptic density was similar to controls. Electrophysiological analysis revealed a pathologically elevated synaptic activity in ChAc MSNs. Treatment with the F-actin stabilizer phallacidin or the Src kinase inhibitor PP2 resulted in the significant reduction of disinhibited synaptic currents to healthy control levels, suggesting a Src kinase- and actin-dependent mechanism. This was underlined by increased G/F-actin ratios and elevated Lyn kinase activity in patient-derived MSNs. These data indicate that F-actin stabilization and Src kinase inhibition represent potential therapeutic targets in ChAc that may restore neuronal function. SIGNIFICANCE STATEMENT Chorea-acanthocytosis (ChAc) is a fatal neurodegenerative disease without a known cure. To gain pathophysiological insight, we newly established a human in vitro model using skin biopsies from ChAc patients to generate disease-specific induced pluripotent stem cells (iPSCs) and developed an efficient iPSC differentiation protocol providing striatal medium spiny neurons. Using patch-clamp electrophysiology, we detected a pathologically enhanced synaptic activity in ChAc neurons. Healthy control levels of synaptic activity could be restored by treatment of ChAc neurons with the F-actin stabilizer phallacidin and the Src kinase inhibitor PP2. Because Src kinases are involved in bridging the membrane to the actin cytoskeleton by membrane protein phosphorylation, our data suggest an actin-dependent mechanism of this dysfunctional phenotype and potential treatment targets in ChAc.
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22
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Ramadass M, Catz SD. Molecular mechanisms regulating secretory organelles and endosomes in neutrophils and their implications for inflammation. Immunol Rev 2017; 273:249-65. [PMID: 27558339 DOI: 10.1111/imr.12452] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neutrophils constitute the first line of cellular defense against invading microorganisms and modulate the subsequent innate and adaptive immune responses. In order to execute a rapid and precise response to infections, neutrophils rely on preformed effector molecules stored in a variety of intracellular granules. Neutrophil granules contain microbicidal factors, the membrane-bound components of the respiratory burst oxidase, membrane-bound adhesion molecules, and receptors that facilitate the execution of all neutrophil functions including adhesion, transmigration, phagocytosis, degranulation, and neutrophil extracellular trap formation. The rapid mobilization of intracellular organelles is regulated by vesicular trafficking mechanisms controlled by effector molecules that include small GTPases and their interacting proteins. In this review, we focus on recent discoveries of mechanistic processes that are at center stage of the regulation of neutrophil function, highlighting the discrete and selective pathways controlled by trafficking modulators. In particular, we describe novel pathways controlled by the Rab27a effectors JFC1 and Munc13-4 in the regulation of degranulation, reactive oxygen species and neutrophil extracellular trap production, and endolysosomal signaling. Finally, we discuss the importance of understanding these molecular mechanisms in order to design novel approaches to modulate neutrophil-mediated inflammatory processes in a targeted fashion.
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Affiliation(s)
- Mahalakshmi Ramadass
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Sergio D Catz
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
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23
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Gorelick FS, Lerch MM. Do Animal Models of Acute Pancreatitis Reproduce Human Disease? Cell Mol Gastroenterol Hepatol 2017; 4:251-262. [PMID: 28752114 PMCID: PMC5518169 DOI: 10.1016/j.jcmgh.2017.05.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 05/26/2017] [Indexed: 12/10/2022]
Abstract
Acute pancreatitis is currently the most common cause of hospital admission among all nonmalignant gastrointestinal diseases. To understand the pathophysiology of the disease and as a potential step toward developing targeted therapies, attempts to induce the disease experimentally began more than 100 years ago. Recent decades have seen progress in developing new experimental pancreatitis models as well as elucidating many underlying cell biological and pathophysiological disease mechanisms. Some models have been developed to reflect specific causes of acute pancreatitis in human beings. However, the paucity of data relating to the molecular mechanisms of human disease, the likelihood that multiple genetic and environmental factors affect the risk of disease development and its severity, and the limited information regarding the natural history of disease in human beings make it difficult to evaluate the value of disease models. Here, we provide an overview of key models and discuss our views on their strengths for characterizing cell biological disease mechanisms or for identifying potential therapeutic targets. We also acknowledge their limitations.
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Affiliation(s)
- Fred S. Gorelick
- Yale University Medical School and Veterans Affairs Medical Center, West Haven, Connecticut
- Correspondence Address correspondence to: Fred S. Gorelick, MD, VA Connecticut Healthcare System/Yale University Medical School, 950 Campbell Avenue, West Haven, Connecticut 06516. fax: (203) 937-3852.VA Connecticut Healthcare System/Yale University Medical School950 Campbell AvenueWest HavenConnecticut 06516
| | - Markus M. Lerch
- Department of Medicine A, University Medicine Greifswald, Greifswald, Germany
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Salari V, Rahnama M, Tuszynski JA. Dissipationless Transfer of Visual Information From Retina to the Primary Visual Cortex in the Human Brain. ACTA ACUST UNITED AC 2017. [DOI: 10.1007/bf03379582] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Abstract
Recently, the experiments on photosynthetic systems via “femto-second laser spectroscopy” methods have indicated that a “quantum-coherence” in the system causes a highly efficient transfer of energy to the “reaction center” (efficiency is approximately equal to 100%). A recent experiment on a single neuron has indicated that it can conduct light. Also, a re-emission of light from both photosynthetic systems and single neurons has been observed, which is called “delayed luminescence”. This can be supposed as a possibility for dissipationless transfer of visual information to the human brain. In addition, a long-range Fröhlich coherence in microtubules can be a candidate for efficient transfer of light through “noisy” and complex structures of the human brain. From an informational point of view it is a legitimate question to ask how human brain can receive subtle external quantum information of photons intact when photons are in a quantum superposition and pass through very noisy and complex pathways from the eye to the brain? Here, we propose a coherent model in which quantum states of photons can be rebuilt in the human brain.
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Ang WG, Church AM, Kulis M, Choi HW, Burks AW, Abraham SN. Mast cell desensitization inhibits calcium flux and aberrantly remodels actin. J Clin Invest 2016; 126:4103-4118. [PMID: 27669462 PMCID: PMC5096925 DOI: 10.1172/jci87492] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 08/16/2016] [Indexed: 11/17/2022] Open
Abstract
Rush desensitization (DS) is a widely used and effective clinical strategy for the rapid inhibition of IgE-mediated anaphylactic responses. However, the cellular targets and underlying mechanisms behind this process remain unclear. Recent studies have implicated mast cells (MCs) as the primary target cells for DS. Here, we developed a murine model of passive anaphylaxis with demonstrated MC involvement and an in vitro assay to evaluate the effect of DS on MCs. In contrast with previous reports, we determined that functional IgE remains on the cell surface of desensitized MCs following DS. Despite notable reductions in MC degranulation following DS, the high-affinity IgE receptor FcεRI was still capable of transducing signals in desensitized MCs. Additionally, we found that displacement of the actin cytoskeleton and its continued association with FcεRI impede the capacity of desensitized MCs to evoke the calcium response that is essential for MC degranulation. Together, these findings suggest that reduced degranulation responses in desensitized MCs arise from aberrant actin remodeling, providing insights that may lead to improvement of DS treatments for anaphylactic responses.
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Affiliation(s)
- W.X. Gladys Ang
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Alison M. Church
- GlaxoSmithKline, Rare Diseases Unit, Research Triangle Park, North Carolina, USA
| | - Mike Kulis
- Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | | | - A. Wesley Burks
- Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Soman N. Abraham
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
- Department of Pathology and
- Department of Immunology, Duke University Medical Center, Durham, North Carolina, USA
- Program in Emerging Infectious Diseases, Duke–National University of Singapore, Singapore
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Mziaut H, Mulligan B, Hoboth P, Otto O, Ivanova A, Herbig M, Schumann D, Hildebrandt T, Dehghany J, Sönmez A, Münster C, Meyer-Hermann M, Guck J, Kalaidzidis Y, Solimena M. The F-actin modifier villin regulates insulin granule dynamics and exocytosis downstream of islet cell autoantigen 512. Mol Metab 2016; 5:656-668. [PMID: 27656403 PMCID: PMC5021679 DOI: 10.1016/j.molmet.2016.05.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 05/20/2016] [Accepted: 05/24/2016] [Indexed: 01/02/2023] Open
Abstract
Objective Insulin release from pancreatic islet β cells should be tightly controlled to avoid hypoglycemia and insulin resistance. The cortical actin cytoskeleton is a gate for regulated exocytosis of insulin secretory granules (SGs) by restricting their mobility and access to the plasma membrane. Prior studies suggest that SGs interact with F-actin through their transmembrane cargo islet cell autoantigen 512 (Ica512) (also known as islet antigen 2/Ptprn). Here we investigated how Ica512 modulates SG trafficking and exocytosis. Methods Transcriptomic changes in Ica512−/− mouse islets were analyzed. Imaging as well as biophysical and biochemical methods were used to validate if and how the Ica512-regulated gene villin modulates insulin secretion in mouse islets and insulinoma cells. Results The F-actin modifier villin was consistently downregulated in Ica512−/− mouse islets and in Ica512-depleted insulinoma cells. Villin was enriched at the cell cortex of β cells and dispersed villin−/− islet cells were less round and less deformable. Basal mobility of SGs in villin-depleted cells was enhanced. Moreover, in cells depleted either of villin or Ica512 F-actin cages restraining cortical SGs were enlarged, basal secretion was increased while glucose-stimulated insulin release was blunted. The latter changes were reverted by overexpressing villin in Ica512-depleted cells, but not vice versa. Conclusion Our findings show that villin controls the size of the F-actin cages restricting SGs and, thus, regulates their dynamics and availability for exocytosis. Evidence that villin acts downstream of Ica512 also indicates that SGs directly influence the remodeling properties of the cortical actin cytoskeleton for tight control of insulin secretion. Ica512-depletion reduces the genetic expression of the F-actin modifier villin. Villin-depletion enhances basal insulin granule mobility and exocytosis. Villin regulates the size of actin cages restraining insulin granules. Villin acts downstream of insulin granule cargo Ica512. The Ica512-villin genetic link enables granules to control cytoskeleton plasticity.
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Key Words
- D, diffusion coefficient
- EGFP, enhanced green fluorescent protein
- F-actin
- Granules
- IPGTT, intraperitoneal glucose tolerance test
- IVGTT, intravenous glucose tolerance test
- Ica512
- Ica512, islet cell autoantigen
- Insulin
- OGTT, oral glucose tolerance test
- RT-DC, real-time deformability cytometry
- SE, standard error
- SG, secretory granules
- Secretion
- TIRFM, total internal reflection fluorescence microscopy
- Villin
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Affiliation(s)
- Hassan Mziaut
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany
| | - Bernard Mulligan
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany
| | - Peter Hoboth
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany
| | - Oliver Otto
- Biotechnology Center Dresden, 01307 Dresden, Germany
| | - Anna Ivanova
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany
| | - Maik Herbig
- Biotechnology Center Dresden, 01307 Dresden, Germany
| | - Desiree Schumann
- Boehringer Ingelheim Pharma GmbH & Co. KG. Cardiometabolic Research, 88397 Biberach, Germany
| | - Tobias Hildebrandt
- Boehringer Ingelheim Pharma GmbH & Co. KG. Cardiometabolic Research, 88397 Biberach, Germany
| | - Jaber Dehghany
- Helmholtz Centre for Infection Research (HZI), Braunschweig Integrated Centre for Systems Biology (BRICS), 38124 Braunschweig, Germany
| | - Anke Sönmez
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany
| | - Carla Münster
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany
| | - Michael Meyer-Hermann
- Helmholtz Centre for Infection Research (HZI), Braunschweig Integrated Centre for Systems Biology (BRICS), 38124 Braunschweig, Germany
| | - Jochen Guck
- Biotechnology Center Dresden, 01307 Dresden, Germany
| | - Yannis Kalaidzidis
- Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Michele Solimena
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany; Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
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Ojima K, Lin ZX, de Andrade IR, Costa ML, Mermelstein C. Distinctive Effects of Cytochalasin B in Chick Primary Myoblasts and Fibroblasts. PLoS One 2016; 11:e0154109. [PMID: 27119825 PMCID: PMC4847871 DOI: 10.1371/journal.pone.0154109] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 04/09/2016] [Indexed: 01/07/2023] Open
Abstract
Actin-based structures play fundamental roles in cellular functions. However it remains controversial how cells cope with the absence of F-actin structures. This report focuses on short- and long-term effects of cytochalasin B (CB) on actin-complexes in fibroblasts and myoblasts. Thirty min of CB treatment dispersed subplasma actin cortices, lamellipodia, ruffled membranes, stress fibers and adhesion plaques into actin patches in fibroblasts and muscle cells. In contrast, 72 hrs CB treatment showed distinct morphological effects. Fibroblasts became giant multinucleated-finger shaped with 5 to 10 protrusions, 3-8 μm in width, and >200 μm in length. They lacked cortical actin, stress fibers, adhesion plaques and ruffled membranes but contained immense lamelliopodia with abnormal adhesion plaque protein complexes. Muscle cells transformed into multinucleated globular-shaped but contained normal I-Z-I and A-bands, indicating that CB did not interfere with the assembly of myofibrils. Within 30 min after CB removal, finger-shaped fibroblasts returned to their original shape and actin-containing structures rapidly reappeared, whereas muscle cells respond slowly to form elongated myotubes following CB washout. The capacity to grow, complete several nuclear cycles, assemble intermediate filaments and microtubules without a morphologically recognizable actin cytoskeleton raises interesting issues related to the role of the actin compartments in eukaryotic cells.
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Affiliation(s)
- Koichi Ojima
- Animal Products Research Division, NARO Institute of Livestock and Grassland Science, Tsukuba, Ibaraki, 305–0901, Japan
| | - Zhong-Xiang Lin
- Department of Cell Biology, Beijing Institute for Cancer Research, Beijing Medical University, Beijing, 100083, China
| | - Ivone Rosa de Andrade
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941–902, Brasil
| | - Manoel Luis Costa
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941–902, Brasil
| | - Claudia Mermelstein
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941–902, Brasil
- * E-mail:
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Satoh K, Narita T, Katsumata-Kato O, Sugiya H, Seo Y. Involvement of myristoylated alanine-rich C kinase substrate phosphorylation and translocation in cholecystokinin-induced amylase release in rat pancreatic acini. Am J Physiol Gastrointest Liver Physiol 2016; 310:G399-409. [PMID: 26744470 DOI: 10.1152/ajpgi.00198.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 01/05/2016] [Indexed: 01/31/2023]
Abstract
Cholecystokinin (CCK) is a gastrointestinal hormone that induces exocytotic amylase release in pancreatic acinar cells. The activation of protein kinase C (PKC) is involved in the CCK-induced pancreatic amylase release. Myristoylated alanine-rich C kinase substrate (MARCKS) is a ubiquitously expressed substrate of PKC. MARCKS has been implicated in membrane trafficking in several cell types. The phosphorylation of MARCKS by PKC results in the translocation of MARCKS from the membrane to the cytosol. Here, we studied the involvement of MARCKS in the CCK-induced amylase release in rat pancreatic acini. Employing Western blotting, we detected MARCKS protein in the rat pancreatic acini. CCK induced MARCKS phosphorylation. A PKC-δ inhibitor, rottlerin, inhibited the CCK-induced MARCKS phosphorylation and amylase release. In the translocation assay, we also observed CCK-induced PKC-δ activation. An immunohistochemistry study showed that CCK induced MARCKS translocation from the membrane to the cytosol. When acini were lysed by a detergent, Triton X-100, CCK partially induced displacement of the MARCKS from the GM1a-rich detergent-resistant membrane fractions (DRMs) in which Syntaxin2 is distributed. A MARCKS-related peptide inhibited the CCK-induced amylase release. These findings suggest that MARCKS phosphorylation by PKC-δ and then MARCKS translocation from the GM1a-rich DRMs to the cytosol are involved in the CCK-induced amylase release in pancreatic acinar cells.
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Affiliation(s)
- Keitaro Satoh
- Department of Regulatory Physiology, Dokkyo Medical University School of Medicine, Tochigi, Japan;
| | - Takanori Narita
- Laboratory of Veterinary Biochemistry, Nihon University College of Bioresource Sciences, Kanagawa, Japan
| | - Osamu Katsumata-Kato
- Department of Physiology, Nihon University School of Dentistry at Matsudo, Chiba, Japan
| | - Hiroshi Sugiya
- Laboratory of Veterinary Biochemistry, Nihon University College of Bioresource Sciences, Kanagawa, Japan
| | - Yoshiteru Seo
- Department of Regulatory Physiology, Dokkyo Medical University School of Medicine, Tochigi, Japan
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Role of Actin Cytoskeleton During Mammalian Sperm Acrosomal Exocytosis. ADVANCES IN ANATOMY, EMBRYOLOGY, AND CELL BIOLOGY 2016; 220:129-44. [PMID: 27194353 DOI: 10.1007/978-3-319-30567-7_7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mammalian sperm require to undergo an exocytotic process called acrosomal exocytosis in order to be able to fuse with the oocyte. This ability is acquired during the course of sperm capacitation. This review is focused on one aspect related to this acquisition: the role of the actin cytoskeleton. Evidence from different laboratories indicates that actin polymerization occurs during capacitation, and the detection of several actin-related proteins suggests that the cytoskeleton is involved in important sperm functions. In other mammalian cells, the cortical actin network acts as a dominant negative clamp which blocks constitutive exocytosis but, at the same time, is necessary to prepare the cell to undergo regulated exocytosis. Thus, F-actin stabilizes structures generated by exocytosis and supports the physiological progression of this process. Is this also the case in mammalian sperm? This review summarizes what is currently known about actin and its related proteins in the male gamete, with particular emphasis on their role in acrosomal exocytosis.
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Park S, Ahuja M, Kim MS, Brailoiu GC, Jha A, Zeng M, Baydyuk M, Wu LG, Wassif CA, Porter FD, Zerfas PM, Eckhaus MA, Brailoiu E, Shin DM, Muallem S. Fusion of lysosomes with secretory organelles leads to uncontrolled exocytosis in the lysosomal storage disease mucolipidosis type IV. EMBO Rep 2015; 17:266-78. [PMID: 26682800 DOI: 10.15252/embr.201541542] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 11/04/2015] [Indexed: 01/29/2023] Open
Abstract
Mutations in TRPML1 cause the lysosomal storage disease mucolipidosis type IV (MLIV). The role of TRPML1 in cell function and how the mutations cause the disease are not well understood. Most studies focus on the role of TRPML1 in constitutive membrane trafficking to and from the lysosomes. However, this cannot explain impaired neuromuscular and secretory cells' functions that mediate regulated exocytosis. Here, we analyzed several forms of regulated exocytosis in a mouse model of MLIV and, opposite to expectations, we found enhanced exocytosis in secretory glands due to enlargement of secretory granules in part due to fusion with lysosomes. Preliminary exploration of synaptic vesicle size, spontaneous mEPSCs, and glutamate secretion in neurons provided further evidence for enhanced exocytosis that was rescued by re-expression of TRPML1 in neurons. These features were not observed in Niemann-Pick type C1. These findings suggest that TRPML1 may guard against pathological fusion of lysosomes with secretory organelles and suggest a new approach toward developing treatment for MLIV.
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Affiliation(s)
- Soonhong Park
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD, USA Department of Oral Biology, BK 21 PLUS Project, Yonsei University College of Dentistry, Seoul, Korea
| | - Malini Ahuja
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD, USA
| | - Min Seuk Kim
- Department of Oral Physiology, School of Dentistry, Wonkwang University, Iksan City, Korea
| | - G Cristina Brailoiu
- Department of Pharmaceutical Sciences, Jefferson School of Pharmacy, Thomas Jefferson University, Philadelphia, PA, USA
| | - Archana Jha
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD, USA
| | - Mei Zeng
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD, USA
| | - Maryna Baydyuk
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Christopher A Wassif
- Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Forbes D Porter
- Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Patricia M Zerfas
- Diagnostic and Research Services Branch, Division of Veterinary Resources, Office of Research Services, National Institutes of Health, Bethesda, MD, USA
| | - Michael A Eckhaus
- Diagnostic and Research Services Branch, Division of Veterinary Resources, Office of Research Services, National Institutes of Health, Bethesda, MD, USA
| | - Eugen Brailoiu
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA, USA
| | - Dong Min Shin
- Department of Oral Biology, BK 21 PLUS Project, Yonsei University College of Dentistry, Seoul, Korea
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD, USA
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Heijnen H, van der Sluijs P. Platelet secretory behaviour: as diverse as the granules … or not? J Thromb Haemost 2015; 13:2141-51. [PMID: 26391322 DOI: 10.1111/jth.13147] [Citation(s) in RCA: 141] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 09/05/2015] [Indexed: 12/19/2022]
Abstract
Platelets play a central role in the arrest of bleeding after damage to a blood vessel and in the development of thrombosis. Platelets rapidly respond after interaction with sub-endothelial components and release cargo from their storage granules. The three principal granule types of platelets are α-granules, dense granules and lysosomes. Timed release of granule contents and regulated expression of critical receptors are essential for maintenance of the platelet thrombus, yet also have important functions beyond hemostasis (i.e. inflammatory reactions and immune responses). α-granules store adhesive molecules such as von Willebrand factor and fibrinogen, growth factors and inflammatory and angiogenic mediators, which play crucial roles in inflammatory responses and tumor genesis. The α-granules comprise a group of subcellular compartments with a unique composition and ultrastructure. Recent studies have suggested that differential secretory kinetics of α-granule subtypes is responsible for a thematic release of adhesive and inflammatory mediators. In addition, new results indicate that activation-dependent synthesis and release of cytokines also contribute to the inflammatory role of platelets. We will discuss the various methods that platelets use to regulate secretory processes and how these relate to potential differential secretion patterns, thereby promoting adhesiveness and/or inflammatory functions. We will focus on the heterogenic granule population, open canalicular system (OCS) plasticity, the role of contractile and mechanobiological forces, and the fusogenic machinery.
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Affiliation(s)
- H Heijnen
- Department of Clinical Chemistry and Hematology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - P van der Sluijs
- Department of Cell Biology, University Medical Center Utrecht, Utrecht, the Netherlands
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Romarowski A, Battistone MA, La Spina FA, Puga Molina LDC, Luque GM, Vitale AM, Cuasnicu PS, Visconti PE, Krapf D, Buffone MG. PKA-dependent phosphorylation of LIMK1 and Cofilin is essential for mouse sperm acrosomal exocytosis. Dev Biol 2015; 405:237-49. [PMID: 26169470 DOI: 10.1016/j.ydbio.2015.07.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 07/01/2015] [Accepted: 07/09/2015] [Indexed: 02/06/2023]
Abstract
Mammalian sperm must acquire their fertilizing ability after a series of biochemical modifications in the female reproductive tract collectively called capacitation to undergo acrosomal exocytosis, a process that is essential for fertilization. Actin dynamics play a central role in controlling the process of exocytosis in somatic cells as well as in sperm from several mammalian species. In somatic cells, small GTPases of the Rho family are widely known as master regulators of actin dynamics. However, the role of these proteins in sperm has not been studied in detail. In the present work we characterized the participation of small GTPases of the Rho family in the signaling pathway that leads to actin polymerization during mouse sperm capacitation. We observed that most of the proteins of this signaling cascade and their effector proteins are expressed in mouse sperm. The activation of the signaling pathways of cAMP/PKA, RhoA/C and Rac1 is essential for LIMK1 activation by phosphorylation on Threonine 508. Serine 3 of Cofilin is phosphorylated by LIMK1 during capacitation in a transiently manner. Inhibition of LIMK1 by specific inhibitors (BMS-3) resulted in lower levels of actin polymerization during capacitation and a dramatic decrease in the percentage of sperm that undergo acrosomal exocytosis. Thus, we demonstrated for the first time that the master regulators of actin dynamics in somatic cells are present and active in mouse sperm. Combining the results of our present study with other results from the literature, we have proposed a working model regarding how LIMK1 and Cofilin control acrosomal exocytosis in mouse sperm.
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Affiliation(s)
- Ana Romarowski
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - María A Battistone
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Florenza A La Spina
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Lis del C Puga Molina
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Guillermina M Luque
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Alejandra M Vitale
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Patricia S Cuasnicu
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Pablo E Visconti
- Department of Veterinary and Animal Science, Paige Labs, University of Massachusets, Amherst, MA 01003, USA
| | - Darío Krapf
- Instituto de Biología Molecular y Celular de Rosario (CONICET-UNR), Rosario 2000 Argentina
| | - Mariano G Buffone
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
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Binker MG, Richards D, Gaisano HY, Cosen-Binker LI. ER stress-associated CTRC mutants decrease stimulated pancreatic zymogen secretion through SIRT2-mediated microtubule dysregulation. Biochem Biophys Res Commun 2015; 463:329-35. [DOI: 10.1016/j.bbrc.2015.05.064] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 05/15/2015] [Indexed: 01/24/2023]
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Identification of key transcription factors in caerulein-induced pancreatitis through expression profiling data. Mol Med Rep 2015; 12:2570-6. [PMID: 25975747 PMCID: PMC4464163 DOI: 10.3892/mmr.2015.3773] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 11/07/2014] [Indexed: 11/16/2022] Open
Abstract
The current study aimed to isolate key transcription factors (TFs) in caerulein-induced pancreatitis, and to identify the difference between wild type and Mist1 knockout (KO) mice, in order to elucidate the contribution of Mist1 to pancreatitis. The gene profile of GSE3644 was downloaded from the Gene Expression Omnibus database then analyzed using the t-test. The isolated differentially expressed genes (DEGs) were mapped into a transcriptional regulatory network derived from the Integrated Transcription Factor Platform database and in the network, the interaction pairs involving at least one DEG were screened. Fisher’s exact test was used to analyze the functional enrichment of the target genes. A total of 1,555 and 3,057 DEGs were identified in the wild type and Mist1KO mice treated with caerulein, respectively. DEGs screened in Mist1KO mice were predominantly enriched in apoptosis, mitogen-activated protein kinase signaling and other cancer-associated pathways. A total of 188 and 51 TFs associated with pathopoiesis were isolated in Mist1KO and wild type mice, respectively. Out of the top 10 TFs (ranked by P-value), 7 TFs, including S-phase kinase-associated protein 2 (Skp2); minichromosome maintenance complex component 3 (Mcm3); cell division cycle 6 (Cdc6); cyclin B1 (Ccnb1); mutS homolog 6 (Msh6); cyclin A2 (Ccna2); and cyclin B2 (Ccnb2), were expressed in the two types of mouse. These TFs were predominantly involved in phosphorylation, DNA replication, cell division and DNA mismatch repair. In addition, specific TFs, including minichromosome maintenance complex component 7 (Mcm7); lymphoid-specific helicase (Hells); and minichromosome maintenance complex component 6 (Mcm6), that function in the unwinding of DNA were identified to participate in Mist1KO pancreatitis. The DEGs, including Cdc6, Mcm6, Msh6 and Wdr1 are closely associated with the regulation of caerulein-induced pancreatitis. Furthermore, other identified TFs were also involved in this type of regulation.
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Masedunskas A, Sramkova M, Weigert R. Homeostasis of the apical plasma membrane during regulated exocytosis in the salivary glands of live rodents. BIOARCHITECTURE 2014; 1:225-229. [PMID: 22754613 PMCID: PMC3384574 DOI: 10.4161/bioa.18405] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In exocrine organs such as the salivary glands, fluids and proteins are secreted into ductal structures by distinct mechanisms that are tightly coupled. In the acinar cells, the major secretory units of the salivary glands, fluids are secreted into the acinar canaliculi through paracellular and intracellular transport, whereas proteins are stored in large granules that undergo exocytosis and fuse with the apical plasma membranes releasing their content into the canaliculi. Both secretory processes elicit a remodeling of the apical plasma membrane that has not been fully addressed in in vitro or ex vivo models. Recently, we have studied regulated exocytosis in the salivary glands of live rodents, focusing on the role that actin and myosin plays in this process. We observed that during exocytosis both secretory granules and canaliculi are subjected to the hydrostatic pressure generated by fluid secretion. Furthermore, the absorption of the membranes of the secretory granules contributes to the expansion and deformation of the canaliculi. Here we suggest that the homeostasis of the apical plasma membranes during exocytosis is maintained by various strategies that include: (1) membrane retrieval via compensatory endocytosis, (2) increase of the surface area via membrane folds and (3) recruitment of a functional actomyosin complex. Our observations underscore the important relationship between tissue architecture and cellular response, and highlight the potential of investigating biological processes in vivo by using intravital microscopy.
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Haddock BJ, Zhu Y, Doyle SP, Abdullah LH, Davis CW. Role of MARCKS in regulated secretion from mast cells and airway goblet cells. Am J Physiol Lung Cell Mol Physiol 2014; 306:L925-36. [PMID: 24705720 DOI: 10.1152/ajplung.00213.2013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
MARCKS (myristoylated alanine-rich C kinase substrate) is postulated to regulate the passage of secretory granules through cortical actin in the early phase of exocytosis. There are, however, three proposed mechanisms of action, all of which were derived from studies using synthetic peptides representing either the central phosphorylation site domain or the upstream, NH2-terminal domain: it tethers actin to the plasma membrane and/or to secretory granules, and/or it sequesters PIP2. Using MARCKS-null mice, we probed for a loss of function secretory phenotype in mast cells harvested from embryonic livers and maturated in vivo [embryonic hepatic-derived mast cells (eHMCs)]. Both wild-type (WT) and MARCKS-null eHMCs exhibited full exocytic responses upon FcϵRI receptor activation with DNP-BSA (2,4-dinitrophenyl-BSA), whether they were in suspension or adherent. The secretory responses of MARCKS-null eHMCs were consistently higher than those of WT cells, but the differences had sporadic statistical significance. The MARCKS-null cells exhibited faster secretory kinetics, however, achieving the plateau phase of the response with a t½ ∼2.5-fold faster. Hence, MARCKS appears to be a nonessential regulatory protein in mast cell exocytosis but exerts a negative modulation. Surprisingly, the MARCKS NH2-terminal peptide, MANS, which has been reported to inhibit mucin secretion from airway goblet cells (Li Y, Martin LD, Spizz G, Adler KB. J Biol Chem 276: 40982-40990, 2001), inhibited hexosaminidase secretion from WT and MARCKS-null eHMCs, leading us to reexamine its effects on mucin secretion. Results from studies using peptide inhibitors with human bronchial epithelial cells and with binding assays using purified mucins suggested that MANS inhibited the mucin binding assay, rather than the secretory response.
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Affiliation(s)
- Brookelyn J Haddock
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina and Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, North Carolina
| | - Yunxiang Zhu
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina and
| | - Sean P Doyle
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina and
| | - Lubna H Abdullah
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina and
| | - C William Davis
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina and Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, North Carolina
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Messenger SW, Falkowski MA, Groblewski GE. Ca²⁺-regulated secretory granule exocytosis in pancreatic and parotid acinar cells. Cell Calcium 2014; 55:369-75. [PMID: 24742357 DOI: 10.1016/j.ceca.2014.03.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 03/04/2014] [Accepted: 03/09/2014] [Indexed: 01/09/2023]
Abstract
Protein secretion from acinar cells of the pancreas and parotid glands is controlled by G-protein coupled receptor activation and generation of the cellular messengers Ca(2+), diacylglycerol and cAMP. Secretory granule (SG) exocytosis shares some common characteristics with nerve, neuroendocrine and endocrine cells which are regulated mainly by elevated cell Ca(2+). However, in addition to diverse signaling pathways, acinar cells have large ∼1 μm diameter SGs (∼30 fold larger diameter than synaptic vesicles), respond to stimulation at slower rates (seconds versus milliseconds), demonstrate significant constitutive secretion, and in isolated acini, undergo sequential compound SG-SG exocytosis at the apical membrane. Exocytosis proceeds as an initial rapid phase that peaks and declines over 3 min followed by a prolonged phase that decays to near basal levels over 20-30 min. Studies indicate the early phase is triggered by Ca(2+) and involves the SG proteins VAMP2 (vesicle associated membrane protein2), Ca(2+)-sensing protein synatotagmin 1 (syt1) and the accessory protein complexin 2. The molecular details for regulation of VAMP8-mediated SG exocytosis and the prolonged phase of secretion are still emerging. Here we review the known regulatory molecules that impact the sequential exocytic process of SG tethering, docking, priming and fusion in acinar cells.
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Affiliation(s)
- Scott W Messenger
- Department of Nutritional Sciences, Graduate Program in Biochemical and Molecular Nutrition, University of Wisconsin, Madison, WI 53706, United States
| | - Michelle A Falkowski
- Department of Nutritional Sciences, Graduate Program in Biochemical and Molecular Nutrition, University of Wisconsin, Madison, WI 53706, United States
| | - Guy E Groblewski
- Department of Nutritional Sciences, Graduate Program in Biochemical and Molecular Nutrition, University of Wisconsin, Madison, WI 53706, United States.
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Clostridium difficile toxin CDT hijacks microtubule organization and reroutes vesicle traffic to increase pathogen adherence. Proc Natl Acad Sci U S A 2014; 111:2313-8. [PMID: 24469807 DOI: 10.1073/pnas.1311589111] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Clostridium difficile causes antibiotic-associated diarrhea and pseudomembranous colitis by the actions of Rho-glucosylating toxins A and B. Recently identified hypervirulent strains, which are associated with increased morbidity and mortality, additionally produce the actin-ADP-ribosylating toxin C. difficile transferase (CDT). CDT depolymerizes actin, causes formation of microtubule-based protrusions, and increases pathogen adherence. Here we show that CDT-induced protrusions allow vesicle traffic and contain endoplasmic reticulum tubules, connected to microtubules via the calcium sensor Stim1. The toxin reroutes Rab11-positive vesicles containing fibronectin, which is involved in bacterial adherence, from basolateral to the apical membrane sides in a microtubule- and Stim1-dependent manner. The data yield a model of C. difficile adherence regulated by actin depolymerization, microtubule restructuring, subsequent Stim1-dependent Ca(2+) signaling, vesicle rerouting, and secretion of ECM proteins to increase bacterial adherence.
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Petersen OH. Calcium signalling and secretory epithelia. Cell Calcium 2014; 55:282-9. [PMID: 24508392 DOI: 10.1016/j.ceca.2014.01.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 01/10/2014] [Indexed: 12/15/2022]
Abstract
Ca(2+) is now firmly established as the most important intracellular regulator of physiological and pathological events in a vast number of different cell types, including secretory epithelia. In these tissues, Ca(2+) signalling is crucially important for the control of both fluid secretion and electrolyte secretion as well as the regulation of macromolecule secretion. In this overview article, I shall attempt to give some general background to the concepts underlying our current thinking about Ca(2+) signalling in epithelia and its roles in regulating secretion. It is outside the scope of this review to provide a comprehensive account of Ca(2+) signalling and the many different processes in the many different secretory epithelia that are controlled by Ca(2+) signals. It is my aim to draw attention to some general features of Ca(2+) signalling processes in secretory epithelia, which are rather different from those in, for example, endocrine glands. The principal examples will be taken from studies of exocrine cells and, in particular, pancreatic acinar cells, as they are the pioneer cells with regard to investigations of Ca(2+) signalling due to primary intracellular Ca(2+) release. They also represent the cell type which has been characterized in most detail with regard to Ca(2+) transport events and mechanisms.
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Affiliation(s)
- O H Petersen
- MRC Secretory Control Research Group, Cardiff School of Biosciences, Cardiff University, The Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, Wales, UK.
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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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Chen PC, Kryukova YN, Shyng SL. Leptin regulates KATP channel trafficking in pancreatic β-cells by a signaling mechanism involving AMP-activated protein kinase (AMPK) and cAMP-dependent protein kinase (PKA). J Biol Chem 2013; 288:34098-34109. [PMID: 24100028 DOI: 10.1074/jbc.m113.516880] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pancreatic β-cells secrete insulin in response to metabolic and hormonal signals to maintain glucose homeostasis. Insulin secretion is under the control of ATP-sensitive potassium (KATP) channels that play key roles in setting β-cell membrane potential. Leptin, a hormone secreted by adipocytes, inhibits insulin secretion by increasing KATP channel conductance in β-cells. We investigated the mechanism by which leptin increases KATP channel conductance. We show that leptin causes a transient increase in surface expression of KATP channels without affecting channel gating properties. This increase results primarily from increased channel trafficking to the plasma membrane rather than reduced endocytosis of surface channels. The effect of leptin on KATP channels is dependent on the protein kinases AMP-activated protein kinase (AMPK) and PKA. Activation of AMPK or PKA mimics and inhibition of AMPK or PKA abrogates the effect of leptin. Leptin activates AMPK directly by increasing AMPK phosphorylation at threonine 172. Activation of PKA leads to increased channel surface expression even in the presence of AMPK inhibitors, suggesting AMPK lies upstream of PKA in the leptin signaling pathway. Leptin signaling also leads to F-actin depolymerization. Stabilization of F-actin pharmacologically occludes, whereas destabilization of F-actin simulates, the effect of leptin on KATP channel trafficking, indicating that leptin-induced actin reorganization underlies enhanced channel trafficking to the plasma membrane. Our study uncovers the signaling and cellular mechanism by which leptin regulates KATP channel trafficking to modulate β-cell function and insulin secretion.
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Affiliation(s)
- Pei-Chun Chen
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239
| | - Yelena N Kryukova
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239
| | - Show-Ling Shyng
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239.
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Singh S, More KR, Chitnis CE. Role of calcineurin and actin dynamics in regulated secretion of microneme proteins in Plasmodium falciparum merozoites during erythrocyte invasion. Cell Microbiol 2013; 16:50-63. [PMID: 23910910 DOI: 10.1111/cmi.12177] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 07/16/2013] [Accepted: 07/30/2013] [Indexed: 11/28/2022]
Abstract
Plasmodium falciparum invades host erythrocytes by multiple invasion pathways. The invasion of erythrocytes by P. falciparum merozoites is a complex process that requires multiple interactions between host receptors and parasite ligands. A number of parasite proteins that mediate interaction with host receptors during invasion are localized to membrane-bound apical organelles referred to as micronemes and rhoptries. The timely release of these proteins to the merozoite surface is crucial for receptor engagement and invasion. It has been demonstrated previously that exposure of merozoites to a low potassium (K(+)) ionic environment as found in blood plasma leads to a rise in cytosolic calcium (Ca(2+)), which triggers microneme secretion. The signalling pathways that regulate microneme discharge in response to rise in cytosolic Ca(2+) are not completely understood. Here, we show that a P. falciparum Ca(2+)-dependent protein phosphatase, calcineurin (PfCN), is an essential regulator of Ca(2+)-dependent microneme exocytosis. An increase in PfCN activity was observed in merozoites following exposure to a low K(+) environment. Treatment of merozoites with calcineurin inhibitors such as FK506 and cyclosporin A prior to transfer to a low K(+) environment resulted in inhibition of secretion of microneme protein apical merozoite antigen-1 (PfAMA-1). Inhibition of PfCN was shown to result in reduced dephosphorylation and depolymerization of apical actin, which appears to be criticalfor microneme secretion. PfCN thus serves as an effector of Ca(2+)-dependent microneme exocytosis by regulating depolymerization of apical actin. Inhibitors that target PfCN block microneme exocytosis and limit growth of P. falciparum blood-stage parasites providing a novel approach towards development of new therapeutic strategies against malaria.
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Affiliation(s)
- Shailja Singh
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
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Abstract
Cellular organelles move within the cellular volume and the effect of the resulting drag forces on the liquid causes bulk movement in the cytosol. The movement of both organelles and cytosol leads to an overall motion pattern called cytoplasmic streaming or cyclosis. This streaming enables the active and passive transport of molecules and organelles between cellular compartments. Furthermore, the fusion and budding of vesicles with and from the plasma membrane (exo/endocytosis) allow for transport of material between the inside and the outside of the cell. In the pollen tube, cytoplasmic streaming and exo/endocytosis are very active and fulfill several different functions. In this review, we focus on the logistics of intracellular motion and transport processes as well as their biophysical underpinnings. We discuss various modeling attempts that have been performed to understand both long-distance shuttling and short-distance targeting of organelles. We show how the combination of mechanical and mathematical modeling with cell biological approaches has contributed to our understanding of intracellular transport logistics.
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Affiliation(s)
- Youssef Chebli
- Département de Sciences Biologiques, Institut de Recherche en Biologie Végétale, Université de Montréal, Montréal, Québec, Canada
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Sabbatini ME, Williams JA. Cholecystokinin-mediated RhoGDI phosphorylation via PKCα promotes both RhoA and Rac1 signaling. PLoS One 2013; 8:e66029. [PMID: 23776598 PMCID: PMC3679036 DOI: 10.1371/journal.pone.0066029] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Accepted: 05/07/2013] [Indexed: 01/18/2023] Open
Abstract
RhoA and Rac1 have been implicated in the mechanism of CCK-induced amylase secretion from pancreatic acini. In all cell types studied to date, inactive Rho GTPases are present in the cytosol bound to the guanine nucleotide dissociation inhibitor RhoGDI. Here, we identified the switch mechanism regulating RhoGDI1-Rho GTPase dissociation and RhoA translocation upon CCK stimulation in pancreatic acini. We found that both Gα13 and PKC, independently, regulate CCK-induced RhoA translocation and that the PKC isoform involved is PKCα. Both RhoGDI1 and RhoGDI3, but not RhoGDI2, are expressed in pancreatic acini. Cytosolic RhoA and Rac1 are associated with RhoGDI1, and CCK-stimulated PKCα activation releases the complex. Overexpression of RhoGDI1, by binding RhoA, inhibits its activation, and thereby, CCK-induced apical amylase secretion. RhoA translocation is also inhibited by RhoGDI1. Inactive Rac1 influences CCK-induced RhoA activation by preventing RhoGDI1 from binding RhoA. By mutational analysis we found that CCK-induced PKCα phosphorylation on RhoGDI1 at Ser96 releases RhoA and Rac1 from RhoGDI1 to facilitate Rho GTPases signaling.
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Affiliation(s)
- Maria Eugenia Sabbatini
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States of America.
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Vaškovičová K, Žárský V, Rösel D, Nikolič M, Buccione R, Cvrčková F, Brábek J. Invasive cells in animals and plants: searching for LECA machineries in later eukaryotic life. Biol Direct 2013; 8:8. [PMID: 23557484 PMCID: PMC3663805 DOI: 10.1186/1745-6150-8-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Accepted: 03/21/2013] [Indexed: 02/08/2023] Open
Abstract
Invasive cell growth and migration is usually considered a specifically metazoan phenomenon. However, common features and mechanisms of cytoskeletal rearrangements, membrane trafficking and signalling processes contribute to cellular invasiveness in organisms as diverse as metazoans and plants – two eukaryotic realms genealogically connected only through the last common eukaryotic ancestor (LECA). By comparing current understanding of cell invasiveness in model cell types of both metazoan and plant origin (invadopodia of transformed metazoan cells, neurites, pollen tubes and root hairs), we document that invasive cell behavior in both lineages depends on similar mechanisms. While some superficially analogous processes may have arisen independently by convergent evolution (e.g. secretion of substrate- or tissue-macerating enzymes by both animal and plant cells), at the heart of cell invasion is an evolutionarily conserved machinery of cellular polarization and oriented cell mobilization, involving the actin cytoskeleton and the secretory pathway. Its central components - small GTPases (in particular RHO, but also ARF and Rab), their specialized effectors, actin and associated proteins, the exocyst complex essential for polarized secretion, or components of the phospholipid- and redox- based signalling circuits (inositol-phospholipid kinases/PIP2, NADPH oxidases) are aparently homologous among plants and metazoans, indicating that they were present already in LECA. Reviewer: This article was reviewed by Arcady Mushegian, Valerian Dolja and Purificacion Lopez-Garcia.
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Affiliation(s)
- Katarína Vaškovičová
- Department of Cell Biology, Faculty of Science, Charles University in Prague, Vinicna 7, 128 43, Prague 2, Czech Republic
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Galkina SI, Fedorova NV, Stadnichuk VI, Sud'ina GF. Membrane tubulovesicular extensions (cytonemes): secretory and adhesive cellular organelles. Cell Adh Migr 2013; 7:174-86. [PMID: 23287580 DOI: 10.4161/cam.23130] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In this review, we summarized data on the formation and structure of the long and highly adhesive membrane tubulovesicular extensions (TVEs, membrane tethers or cytonemes) observed in human neutrophils and other mammalian cells, protozoan parasites and bacteria. We determined that TVEs are membrane protrusions characterized by a uniform diameter (130-250 nm for eukaryotic cells and 60-90 nm for bacteria) along the entire length, an outstanding length and high rate of development and a high degree of flexibility and capacity for shedding from the cells. This review represents TVEs as protrusions of the cellular secretory process, serving as intercellular adhesive organelles in eukaryotic cells and bacteria. An analysis of the physical and chemical approaches to induce TVEs formation revealed that disrupting the actin cytoskeleton and inhibiting glucose metabolism or vacuolar-type ATPase induces TVE formation in eukaryotic cells. Nitric oxide is represented as a physiological regulator of TVE formation.
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Affiliation(s)
- Svetlana I Galkina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
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Xu J, Toops KA, Diaz F, Carvajal-Gonzalez JM, Gravotta D, Mazzoni F, Schreiner R, Rodriguez-Boulan E, Lakkaraju A. Mechanism of polarized lysosome exocytosis in epithelial cells. J Cell Sci 2012; 125:5937-43. [PMID: 23038769 DOI: 10.1242/jcs.109421] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fusion of lysosomes with the plasma membrane is a calcium-dependent process that is crucial for membrane repair, limiting pathogen entry and clearing cellular debris. In non-polarized cells, lysosome exocytosis facilitates rapid resealing of torn membranes. Here, we investigate the mechanism of lysosome exocytosis in polarized epithelia, the main barrier between the organism and the external environment and the first line of defense against pathogens. We find that in polarized Madin-Darby canine kidney (MDCK) cells, calcium ionophores or pore-forming toxins cause lysosomes to fuse predominantly with the basolateral membrane. This polarized exocytosis is regulated by the actin cytoskeleton, membrane cholesterol and the clathrin adaptor AP-1. Depolymerization of actin, but not microtubules, causes apical lysosome fusion, supporting the hypothesis that cortical actin is a barrier to exocytosis. Overloading lysosomes with cholesterol inhibits exocytosis, suggesting that excess cholesterol paralyzes lysosomal traffic. The clathrin adaptor AP-1 is responsible for accurately targeting syntaxin 4 to the basolateral domain. In cells lacking either the ubiquitous AP-1A or the epithelial-specific AP-1B, syntaxin 4 is non-polar. This causes lysosomes to fuse with both the apical and basolateral membranes. Consistent with these findings, RNAi-mediated depletion of syntaxin 4 inhibits basolateral exocytosis in wild-type MDCK, and both apical and basolateral exocytosis in cells lacking AP-1A or AP-1B. Our results provide fundamental insight into the molecular machinery involved in membrane repair in polarized epithelia and suggest that AP-1 is a crucial regulator of this process.
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Affiliation(s)
- Jin Xu
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
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Multiple roles for the actin cytoskeleton during regulated exocytosis. Cell Mol Life Sci 2012; 70:2099-121. [PMID: 22986507 DOI: 10.1007/s00018-012-1156-5] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/28/2012] [Accepted: 08/30/2012] [Indexed: 01/01/2023]
Abstract
Regulated exocytosis is the main mechanism utilized by specialized secretory cells to deliver molecules to the cell surface by virtue of membranous containers (i.e., secretory vesicles). The process involves a series of highly coordinated and sequential steps, which include the biogenesis of the vesicles, their delivery to the cell periphery, their fusion with the plasma membrane, and the release of their content into the extracellular space. Each of these steps is regulated by the actin cytoskeleton. In this review, we summarize the current knowledge regarding the involvement of actin and its associated molecules during each of the exocytic steps in vertebrates, and suggest that the overall role of the actin cytoskeleton during regulated exocytosis is linked to the architecture and the physiology of the secretory cells under examination. Specifically, in neurons, neuroendocrine, endocrine, and hematopoietic cells, which contain small secretory vesicles that undergo rapid exocytosis (on the order of milliseconds), the actin cytoskeleton plays a role in pre-fusion events, where it acts primarily as a functional barrier and facilitates docking. In exocrine and other secretory cells, which contain large secretory vesicles that undergo slow exocytosis (seconds to minutes), the actin cytoskeleton plays a role in post-fusion events, where it regulates the dynamics of the fusion pore, facilitates the integration of the vesicles into the plasma membrane, provides structural support, and promotes the expulsion of large cargo molecules.
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Jang Y, Soekmadji C, Mitchell JM, Thomas WG, Thorn P. Real-time measurement of F-actin remodelling during exocytosis using Lifeact-EGFP transgenic animals. PLoS One 2012; 7:e39815. [PMID: 22768313 PMCID: PMC3388092 DOI: 10.1371/journal.pone.0039815] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 05/26/2012] [Indexed: 11/25/2022] Open
Abstract
F-actin remodelling is essential for a wide variety of cell processes. It is important in exocytosis, where F-actin coats fusing exocytic granules. The purpose of these F-actin coats is unknown. They may be important in stabilizing the fused granules, they may play a contractile role and promote expulsion of granule content and finally may be important in endocytosis. To elucidate these functions of F-actin remodelling requires a reliable method to visualize F-actin dynamics in living cells. The recent development of Lifeact-EGFP transgenic animals offers such an opportunity. Here, we studied the characteristics of exocytosis in pancreatic acinar cells obtained from the Lifeact-EGFP transgenic mice. We show that the time-course of agonist-evoked exocytic events and the kinetics of each single exocytic event are the same for wild type and Lifeact-EGFP transgenic animals. We conclude that Lifeact-EGFP animals are a good model to study of exocytosis and reveal that F-actin coating is dependent on the de novo synthesis of F-actin and that development of actin polymerization occurs simultaneously in all regions of the granule. Our insights using the Lifeact-EGFP mice demonstrate that F-actin coating occurs after granule fusion and is a granule-wide event.
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Affiliation(s)
- Yujin Jang
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Carolina Soekmadji
- The Australian Prostate Research Centre – Queensland, Princess Alexandra Hospital, Buranda, Queensland, Australia
| | - Justin M. Mitchell
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Walter G. Thomas
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Peter Thorn
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
- * E-mail:
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