1
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Chen GL, Li JY, Chen X, Liu JW, Zhang Q, Liu JY, Wen J, Wang N, Lei M, Wei JP, Yi L, Li JJ, Ling YP, Yi HQ, Hu Z, Duan J, Zhang J, Zeng B. Mechanosensitive channels TMEM63A and TMEM63B mediate lung inflation-induced surfactant secretion. J Clin Invest 2024; 134:e174508. [PMID: 38127458 PMCID: PMC10904053 DOI: 10.1172/jci174508] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 12/20/2023] [Indexed: 12/23/2023] Open
Abstract
Pulmonary surfactant is a lipoprotein complex lining the alveolar surface to decrease the surface tension and facilitate inspiration. Surfactant deficiency is often seen in premature infants and in children and adults with respiratory distress syndrome. Mechanical stretch of alveolar type 2 epithelial (AT2) cells during lung expansion is the primary physiological factor that stimulates surfactant secretion; however, it is unclear whether there is a mechanosensor dedicated to this process. Here, we show that loss of the mechanosensitive channels TMEM63A and TMEM63B (TMEM63A/B) resulted in atelectasis and respiratory failure in mice due to a deficit of surfactant secretion. TMEM63A/B were predominantly localized at the limiting membrane of the lamellar body (LB), a lysosome-related organelle that stores pulmonary surfactant and ATP in AT2 cells. Activation of TMEM63A/B channels during cell stretch facilitated the release of surfactant and ATP from LBs fused with the plasma membrane. The released ATP evoked Ca2+ signaling in AT2 cells and potentiated exocytic fusion of more LBs. Our study uncovered a vital physiological function of TMEM63 mechanosensitive channels in preparing the lungs for the first breath at birth and maintaining respiration throughout life.
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Affiliation(s)
- Gui-Lan Chen
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - Jing-Yi Li
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - Xin Chen
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - Jia-Wei Liu
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - Qian Zhang
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - Jie-Yu Liu
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - Jing Wen
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - Na Wang
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - Ming Lei
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - Jun-Peng Wei
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - Li Yi
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - Jia-Jia Li
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - Yu-Peng Ling
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
| | - He-Qiang Yi
- Department of Cardiothoracic Surgery, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, Sichuan, China
| | - Zhenying Hu
- Human Aging Research Institute and School of Life Sciences and
| | - Jingjing Duan
- Human Aging Research Institute and School of Life Sciences and
| | - Jin Zhang
- School of Basic Medical Sciences, Nanchang University, Nanchang, Jiangxi, China
| | - Bo Zeng
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, and
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2
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Heydecker M, Shitara A, Chen D, Tran DT, Masedunskas A, Tora MS, Ebrahim S, Appaduray MA, Galeano Niño JL, Bhardwaj A, Narayan K, Hardeman EC, Gunning PW, Weigert R. Coordination of force-generating actin-based modules stabilizes and remodels membranes in vivo. J Cell Biol 2024; 223:e202401091. [PMID: 39172125 PMCID: PMC11344176 DOI: 10.1083/jcb.202401091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 06/18/2024] [Accepted: 08/07/2024] [Indexed: 08/23/2024] Open
Abstract
Membrane remodeling drives a broad spectrum of cellular functions, and it is regulated through mechanical forces exerted on the membrane by cytoplasmic complexes. Here, we investigate how actin filaments dynamically tune their structure to control the active transfer of membranes between cellular compartments with distinct compositions and biophysical properties. Using intravital subcellular microscopy in live rodents we show that a lattice composed of linear filaments stabilizes the granule membrane after fusion with the plasma membrane and a network of branched filaments linked to the membranes by Ezrin, a regulator of membrane tension, initiates and drives to completion the integration step. Our results highlight how the actin cytoskeleton tunes its structure to adapt to dynamic changes in the biophysical properties of membranes.
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Affiliation(s)
- Marco Heydecker
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- School of Biomedical Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Akiko Shitara
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Department of Pharmacology, Asahi University School of Dentistry, Gifu, Japan
| | - Desu Chen
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Duy T. Tran
- NIDCR Imaging Core, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Andrius Masedunskas
- School of Biomedical Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Muhibullah S. Tora
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Seham Ebrahim
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Department of Molecular Physiology and Biological Physics, Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Mark A. Appaduray
- School of Biomedical Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Jorge Luis Galeano Niño
- EMBL Australia, Single Molecule Science node, University of New South Wales Sydney, Sydney, Australia
| | - Abhishek Bhardwaj
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Kedar Narayan
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Edna C. Hardeman
- School of Biomedical Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Peter W. Gunning
- School of Biomedical Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Roberto Weigert
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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3
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Hanusrichterova J, Mokry J, Al-Saiedy MR, Koetzler R, Amrein MW, Green FHY, Calkovska A. Factors influencing airway smooth muscle tone: a comprehensive review with a special emphasis on pulmonary surfactant. Am J Physiol Cell Physiol 2024; 327:C798-C816. [PMID: 39099420 DOI: 10.1152/ajpcell.00337.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Revised: 07/23/2024] [Accepted: 07/25/2024] [Indexed: 08/06/2024]
Abstract
A thin film of pulmonary surfactant lines the surface of the airways and alveoli, where it lowers the surface tension in the peripheral lungs, preventing collapse of the bronchioles and alveoli and reducing the work of breathing. It also possesses a barrier function for maintaining the blood-gas interface of the lungs and plays an important role in innate immunity. The surfactant film covers the epithelium lining both large and small airways, forming the first line of defense between toxic airborne particles/pathogens and the lungs. Furthermore, surfactant has been shown to relax airway smooth muscle (ASM) after exposure to ASM agonists, suggesting a more subtle function. Whether surfactant masks irritant sensory receptors or interacts with one of them is not known. The relaxant effect of surfactant on ASM is absent in bronchial tissues denuded of an epithelial layer. Blocking of prostanoid synthesis inhibits the relaxant function of surfactant, indicating that prostanoids might be involved. Another possibility for surfactant to be active, namely through ATP-dependent potassium channels and the cAMP-regulated epithelial chloride channels [cystic fibrosis transmembrane conductance regulators (CFTRs)], was tested but could not be confirmed. Hence, this review discusses the mechanisms of known and potential relaxant effects of pulmonary surfactant on ASM. This review summarizes what is known about the role of surfactant in smooth muscle physiology and explores the scientific questions and studies needed to fully understand how surfactant helps maintain the delicate balance between relaxant and constrictor needs.
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Affiliation(s)
- Juliana Hanusrichterova
- Biomedical Centre Martin, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
- Department of Physiology, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
| | - Juraj Mokry
- Department of Pharmacology, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
| | - Mustafa R Al-Saiedy
- Department of Internal Medicine, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Rommy Koetzler
- Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Matthias W Amrein
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada
| | - Francis H Y Green
- Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Andrea Calkovska
- Department of Physiology, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
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4
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Inoue S, Nagao J, Kawamoto K, Kan-o K, Fukuyama S, Sasaki S, Kudo S, Okamoto I, Sera T. Overstretching alveolar epithelial type II cells decreases surfactant secretion via actin polymerization and intracellular trafficking alteration. Heliyon 2024; 10:e33499. [PMID: 39040228 PMCID: PMC11260927 DOI: 10.1016/j.heliyon.2024.e33499] [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: 03/04/2024] [Revised: 05/27/2024] [Accepted: 06/21/2024] [Indexed: 07/24/2024] Open
Abstract
Pulmonary surfactant is essential for maintaining proper lung function. Alveolar epithelial type II (AE2) cells secrete surfactants via lamellar bodies (LBs). In tidal loading during each breath, the physiological cyclic stretching of AE2 cells promotes surfactant secretion. Excessive stretching inhibits surfactant secretion, which is considered to contribute to the development of lung damage. However, its precise mechanism remains unknown. This study tested whether actin polymerization and intracellular transport are required for pulmonary surfactant secretion and the association of actin polymerization and transport in identical human AE2-derived A549 cells using live-cell imaging, not in the bulk cells population. We found that overstretching approximately doubled actin polymerization into filaments (F-actin) and suppressed LB secretion by half in the fluorescent area ratio, compared with physiological stretching (F-actin: 1.495 vs 0.643 (P < 0.01); LB: 0.739 vs 0.332 (P < 0.01)). An inhibitor of actin polymerization increased LB secretion. Intracellular tracking using fluorescent particles revealed that cyclic stretching shifted the particle motion perpendicularly to the direction of stretching according to the orientation of the F-actin (proportion of perpendicular axis motion prior particle: 0h 40.12 % vs 2h 63.13 % (P < 0.01)), and particle motion was restricted over time in the cells subjected to overstretching, indicating that overstretching regulates intracellular transport dynamics (proportion of stop motion particle: 0h 1.01 % vs 2h 11.04 % (P < 0.01)). These findings suggest that overstretching changes secretion through the cytoskeleton: overstretching AE2 cells inhibits pulmonary surfactant secretion, at least through accelerating actin polymerization and decreasing intracellular trafficking, and the change in actin orientation would modulate intracellular trafficking.
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Affiliation(s)
- Shigesato Inoue
- Department of Respiratory Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
- Department of Mechanical Engineering, Graduate School of Engineering, Kyushu University, Fukuoka, Japan
| | - Junpei Nagao
- Department of Mechanical Engineering, Graduate School of Engineering, Kyushu University, Fukuoka, Japan
| | - Kouhei Kawamoto
- Department of Mechanical Engineering, Graduate School of Engineering, Kyushu University, Fukuoka, Japan
| | - Keiko Kan-o
- Department of Respiratory Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Satoru Fukuyama
- Department of Respiratory Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
- Department of Respiratory Medicine, National Hospital Organization Omuta National Hospital, Fukuoka, Japan
| | - Saori Sasaki
- Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka, Japan
| | - Susumu Kudo
- Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka, Japan
| | - Isamu Okamoto
- Department of Respiratory Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Toshihiro Sera
- Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka, Japan
- Department of Medical and Robotic Engineering Design, Faculty of Advanced Engineering, Tokyo University of Science, Tokyo, Japan
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5
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Heydecker M, Shitara A, Chen D, Tran D, Masedunskas A, Tora M, Ebrahim S, Appaduray MA, Galeano Niño JL, Bhardwaj A, Narayan K, Hardeman EC, Gunning PW, Weigert R. Spatial and Temporal Coordination of Force-generating Actin-based Modules Drives Membrane Remodeling In Vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.04.569944. [PMID: 38168275 PMCID: PMC10760165 DOI: 10.1101/2023.12.04.569944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Membrane remodeling drives a broad spectrum of cellular functions, and it is regulated through mechanical forces exerted on the membrane by cytoplasmic complexes. Here, we investigate how actin filaments dynamically tune their structure to control the active transfer of membranes between cellular compartments with distinct compositions and biophysical properties. Using intravital subcellular microscopy in live rodents we show that: a lattice composed of linear filaments stabilizes the granule membrane after fusion with the plasma membrane; and a network of branched filaments linked to the membranes by Ezrin, a regulator of membrane tension, initiates and drives to completion the integration step. Our results highlight how the actin cytoskeleton tunes its structure to adapt to dynamic changes in the biophysical properties of membranes.
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6
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Biton T, Scher N, Carmon S, Elbaz-Alon Y, Schejter ED, Shilo BZ, Avinoam O. Fusion pore dynamics of large secretory vesicles define a distinct mechanism of exocytosis. J Cell Biol 2023; 222:e202302112. [PMID: 37707500 PMCID: PMC10501449 DOI: 10.1083/jcb.202302112] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 07/06/2023] [Accepted: 08/24/2023] [Indexed: 09/15/2023] Open
Abstract
Exocrine cells utilize large secretory vesicles (LSVs) up to 10 μm in diameter. LSVs fuse with the apical surface, often recruiting actomyosin to extrude their content through dynamic fusion pores. The molecular mechanism regulating pore dynamics remains largely uncharacterized. We observe that the fusion pores of LSVs in the Drosophila larval salivary glands expand, stabilize, and constrict. Arp2/3 is essential for pore expansion and stabilization, while myosin II is essential for pore constriction. We identify several Bin-Amphiphysin-Rvs (BAR) homology domain proteins that regulate fusion pore expansion and stabilization. We show that the I-BAR protein Missing-in-Metastasis (MIM) localizes to the fusion site and is essential for pore expansion and stabilization. The MIM I-BAR domain is essential but not sufficient for localization and function. We conclude that MIM acts in concert with actin, myosin II, and additional BAR-domain proteins to control fusion pore dynamics, mediating a distinct mode of exocytosis, which facilitates actomyosin-dependent content release that maintains apical membrane homeostasis during secretion.
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Affiliation(s)
- Tom Biton
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Nadav Scher
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Shari Carmon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Yael Elbaz-Alon
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Eyal D. Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Ori Avinoam
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
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7
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An Overview of Cell Membrane Perforation and Resealing Mechanisms for Localized Drug Delivery. Pharmaceutics 2022; 14:pharmaceutics14040886. [PMID: 35456718 PMCID: PMC9031838 DOI: 10.3390/pharmaceutics14040886] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 04/09/2022] [Accepted: 04/14/2022] [Indexed: 01/04/2023] Open
Abstract
Localized and reversible plasma membrane disruption is a promising technique employed for the targeted deposition of exogenous therapeutic compounds for the treatment of disease. Indeed, the plasma membrane represents a significant barrier to successful delivery, and various physical methods using light, sound, and electrical energy have been developed to generate cell membrane perforations to circumvent this issue. To restore homeostasis and preserve viability, localized cellular repair mechanisms are subsequently triggered to initiate a rapid restoration of plasma membrane integrity. Here, we summarize the known emergency membrane repair responses, detailing the salient membrane sealing proteins as well as the underlying cytoskeletal remodeling that follows the physical induction of a localized plasma membrane pore, and we present an overview of potential modulation strategies that may improve targeted drug delivery approaches.
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8
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Liu X, Huan P, Liu B. Nonmuscle Myosin II is Required for Larval Shell Formation in a Patellogastropod. Front Cell Dev Biol 2022; 10:813741. [PMID: 35186928 PMCID: PMC8851382 DOI: 10.3389/fcell.2022.813741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 01/11/2022] [Indexed: 11/13/2022] Open
Abstract
The molecular mechanisms underlying larval shell development in mollusks remain largely elusive. We previously found evident filamentous actin (F-actin) aggregations in the developing shell field of the patellogastropod Lottia goshimai, indicating roles of actomyosin networks in the process. In the present study, we functionally characterized nonmuscle myosin II (NM II), the key molecule in actomyosin networks, in the larval shell development of L. goshimai. Immunostaining revealed general colocalization of phosphorylated NM II and F-actin in the shell field. When inhibiting the phosphorylation of NM II using the specific inhibitor blebbistatin in one- or 2-h periods during shell field morphogenesis (6–8 h post-fertilization, hpf), the larval shell plate was completely lost in the veliger larva (24 hpf). Scanning electron microscopy revealed that the nascent larval shell plate could not be developed in the manipulated larvae (10 hpf). Further investigations revealed that key events in shell field morphogenesis were inhibited by blebbistatin pulses, including invagination of the shell field and cell shape changes and cell rearrangements during shell field morphogenesis. These factors caused the changed morphology of the shell field, despite the roughly retained “rosette” organization. To explore whether the specification of related cells was affected by blebbistatin treatments, we investigated the expression of four potential shell formation genes (bmp2/4, gata2/3, hox1 and engrailed). The four genes did not show evident changes in expression level, indicating unaffected cell specification in the shell field, while the gene expression patterns showed variations according to the altered morphology of the shell field. Together, our results reveal that NM II contributes to the morphogenesis of the shell field and is crucial for the formation of the larval shell plate in L. goshimai. These results add to the knowledge of the mechanisms of molluskan shell development.
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Affiliation(s)
- Xinyu Liu
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Pin Huan
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
| | - Baozhong Liu
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Baozhong Liu,
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9
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Rogerson C, Wotherspoon DJ, Tommasi C, Button RW, O'Shaughnessy RFL. Akt1-associated actomyosin remodelling is required for nuclear lamina dispersal and nuclear shrinkage in epidermal terminal differentiation. Cell Death Differ 2021; 28:1849-1864. [PMID: 33462407 PMCID: PMC8184862 DOI: 10.1038/s41418-020-00712-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 12/14/2020] [Accepted: 12/16/2020] [Indexed: 01/30/2023] Open
Abstract
Keratinocyte cornification and epidermal barrier formation are tightly controlled processes, which require complete degradation of intracellular organelles, including removal of keratinocyte nuclei. Keratinocyte nuclear destruction requires Akt1-dependent phosphorylation and degradation of the nuclear lamina protein, Lamin A/C, essential for nuclear integrity. However, the molecular mechanisms that result in complete nuclear removal and their regulation are not well defined. Post-confluent cultures of rat epidermal keratinocytes (REKs) undergo spontaneous and complete differentiation, allowing visualisation and perturbation of the differentiation process in vitro. We demonstrate that there is dispersal of phosphorylated Lamin A/C to structures throughout the cytoplasm in differentiating keratinocytes. We show that the dispersal of phosphorylated Lamin A/C is Akt1-dependent and these structures are specific for the removal of Lamin A/C from the nuclear lamina; nuclear contents and Lamin B were not present in these structures. Immunoprecipitation identified a group of functionally related Akt1 target proteins involved in Lamin A/C dispersal, including actin, which forms cytoskeletal microfilaments, Arp3, required for actin filament nucleation, and Myh9, a component of myosin IIa, a molecular motor that can translocate along actin filaments. Disruption of actin filament polymerisation, nucleation or myosin IIa activity prevented formation and dispersal of cytoplasmic Lamin A/C structures. Live imaging of keratinocytes expressing fluorescently tagged nuclear proteins showed a nuclear volume reduction step taking less than 40 min precedes final nuclear destruction. Preventing Akt1-dependent Lamin A/C phosphorylation and disrupting cytoskeletal Akt1-associated proteins prevented nuclear volume reduction. We propose keratinocyte nuclear destruction and differentiation requires myosin II activity and the actin cytoskeleton for two intermediate processes: Lamin A/C dispersal and rapid nuclear volume reduction.
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Affiliation(s)
- Clare Rogerson
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Duncan J Wotherspoon
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Cristina Tommasi
- Immunobiology and Dermatology, UCL Great Ormond Street Institute of Child Health, London, UK
- School of Cellular & Molecular Medicine, University of Bristol, Bristol, UK
| | - Robert W Button
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Ryan F L O'Shaughnessy
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
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10
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Modzelewska K, Brown L, Culotti J, Moghal N. Sensory regulated Wnt production from neurons helps make organ development robust to environmental changes in C. elegans. Development 2020; 147:dev186080. [PMID: 32586974 DOI: 10.1242/dev.186080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 06/13/2020] [Indexed: 11/20/2022]
Abstract
Long-term survival of an animal species depends on development being robust to environmental variations and climate changes. We used C. elegans to study how mechanisms that sense environmental changes trigger adaptive responses that ensure animals develop properly. In water, the nervous system induces an adaptive response that reinforces vulval development through an unknown backup signal for vulval induction. This response involves the heterotrimeric G-protein EGL-30//Gαq acting in motor neurons. It also requires body-wall muscle, which is excited by EGL-30-stimulated synaptic transmission, suggesting a behavioral function of neurons induces backup signal production from muscle. We now report that increased acetylcholine during liquid growth activates an EGL-30-Rho pathway, distinct from the synaptic transmission pathway, that increases Wnt production from motor neurons. We also provide evidence that this neuronal Wnt contributes to EGL-30-stimulated vulval development, with muscle producing a parallel developmental signal. As diverse sensory modalities stimulate motor neurons via acetylcholine, this mechanism enables broad sensory perception to enhance Wnt-dependent development. Thus, sensory perception improves animal fitness by activating distinct neuronal functions that trigger adaptive changes in both behavior and developmental processes.
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Affiliation(s)
- Katarzyna Modzelewska
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - Louise Brown
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada
| | - Joseph Culotti
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada
| | - Nadeem Moghal
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
- Princess Margaret Cancer Centre/University Health Network, Toronto, Ontario, M5G 1L7, Canada
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11
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Miklavc P, Frick M. Actin and Myosin in Non-Neuronal Exocytosis. Cells 2020; 9:cells9061455. [PMID: 32545391 PMCID: PMC7348895 DOI: 10.3390/cells9061455] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/03/2020] [Accepted: 06/06/2020] [Indexed: 12/18/2022] Open
Abstract
Cellular secretion depends on exocytosis of secretory vesicles and discharge of vesicle contents. Actin and myosin are essential for pre-fusion and post-fusion stages of exocytosis. Secretory vesicles depend on actin for transport to and attachment at the cell cortex during the pre-fusion phase. Actin coats on fused vesicles contribute to stabilization of large vesicles, active vesicle contraction and/or retrieval of excess membrane during the post-fusion phase. Myosin molecular motors complement the role of actin. Myosin V is required for vesicle trafficking and attachment to cortical actin. Myosin I and II members engage in local remodeling of cortical actin to allow vesicles to get access to the plasma membrane for membrane fusion. Myosins stabilize open fusion pores and contribute to anchoring and contraction of actin coats to facilitate vesicle content release. Actin and myosin function in secretion is regulated by a plethora of interacting regulatory lipids and proteins. Some of these processes have been first described in non-neuronal cells and reflect adaptations to exocytosis of large secretory vesicles and/or secretion of bulky vesicle cargoes. Here we collate the current knowledge and highlight the role of actomyosin during distinct phases of exocytosis in an attempt to identify unifying molecular mechanisms in non-neuronal secretory cells.
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Affiliation(s)
- Pika Miklavc
- School of Science, Engineering & Environment, University of Salford, Manchester M5 4WT, UK
- Correspondence: (P.M.); (M.F.); Tel.: +44-0161-295-3395 (P.M.); +49-731-500-23115 (M.F.); Fax: +49-731-500-23242 (M.F.)
| | - Manfred Frick
- Institute of General Physiology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
- Correspondence: (P.M.); (M.F.); Tel.: +44-0161-295-3395 (P.M.); +49-731-500-23115 (M.F.); Fax: +49-731-500-23242 (M.F.)
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12
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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: 2.4] [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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13
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Ryan AQ, Chan CJ, Graner F, Hiiragi T. Lumen Expansion Facilitates Epiblast-Primitive Endoderm Fate Specification during Mouse Blastocyst Formation. Dev Cell 2019; 51:684-697.e4. [PMID: 31735667 PMCID: PMC6912163 DOI: 10.1016/j.devcel.2019.10.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 06/29/2019] [Accepted: 10/14/2019] [Indexed: 12/21/2022]
Abstract
Epithelial tissues typically form lumina. In mammalian blastocysts, in which the first embryonic lumen forms, many studies have investigated how the cell lineages are specified through genetics and signaling, whereas potential roles of the fluid lumen have yet to be investigated. We discover that in mouse pre-implantation embryos at the onset of lumen formation, cytoplasmic vesicles are secreted into intercellular space. The segregation of epiblast and primitive endoderm directly follows lumen coalescence. Notably, pharmacological and biophysical perturbation of lumen expansion impairs the specification and spatial segregation of primitive endoderm cells within the blastocyst. Luminal deposition of FGF4 expedites fate specification and partially rescues the reduced specification in blastocysts with smaller cavities. Combined, our results suggest that blastocyst lumen expansion plays a critical role in guiding cell fate specification and positioning, possibly mediated by luminally deposited FGF4. Lumen expansion may provide a general mechanism for tissue pattern formation. Lumenogenesis coincides with cytoplasmic vesicle release into intercellular space Mouse blastocyst epiblast-primitive endoderm segregation follows lumen expansion Reduced lumen expansion impairs cell fate specification and segregation Luminally deposited FGF4 expedites epiblast-primitive endoderm specification
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Affiliation(s)
- Allyson Quinn Ryan
- Developmental Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; Laboratoire Matière et Systèmes Complexes, Université Denis Diderot, Paris 7, CNRS UMR 7057, Condorcet Building 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France
| | - Chii Jou Chan
- Developmental Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - François Graner
- Laboratoire Matière et Systèmes Complexes, Université Denis Diderot, Paris 7, CNRS UMR 7057, Condorcet Building 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France
| | - Takashi Hiiragi
- Developmental Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; Institute for the Advanced Study of Human Biology (WPI-ASHBi), Kyoto University, Kyoto, Japan.
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14
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Sulzer D, Edwards RH. The physiological role of α-synuclein and its relationship to Parkinson's Disease. J Neurochem 2019; 150:475-486. [PMID: 31269263 PMCID: PMC6707892 DOI: 10.1111/jnc.14810] [Citation(s) in RCA: 214] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/03/2019] [Accepted: 06/28/2019] [Indexed: 12/15/2022]
Abstract
The protein α-synuclein has a central role in the pathogenesis of Parkinson's disease (PD). In this review, we discuss recent results concerning its primary function, which appears to be on cell membranes. The pre-synaptic location of synuclein has suggested a role in neurotransmitter release and it apparently associates with synaptic vesicles because of their high curvature. Indeed, synuclein over-expression inhibits synaptic vesicle exocytosis. However, loss of synuclein has not yet been shown to have a major effect on synaptic transmission. Consistent with work showing that synuclein can promote as well as sense membrane curvature, recent analysis of synuclein triple knockout mice now shows that synuclein accelerates dilation of the exocytic fusion pore. This form of regulation affects primarily the release of slowly discharged lumenal cargo such as neural peptides, but presumably also contributes to maintenance of the release site. This article is part of the Special Issue "Synuclein".
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Affiliation(s)
- David Sulzer
- Departments of Psychiatry, Neurology and Pharmacology, Columbia University Medical Center, New York State Psychiatric Institute
| | - Robert H Edwards
- Departments of Neurology and Physiology, Graduate Programs in Cell Biology, Biomedical Sciences and Neuroscience, UCSF School of Medicine
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15
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Müller MT, Schempp R, Lutz A, Felder T, Felder E, Miklavc P. Interaction of microtubules and actin during the post-fusion phase of exocytosis. Sci Rep 2019; 9:11973. [PMID: 31427591 PMCID: PMC6700138 DOI: 10.1038/s41598-019-47741-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 07/09/2019] [Indexed: 01/24/2023] Open
Abstract
Exocytosis is the intracellular trafficking step where a secretory vesicle fuses with the plasma membrane to release vesicle content. Actin and microtubules both play a role in exocytosis; however, their interplay is not understood. Here we study the interaction of actin and microtubules during exocytosis in lung alveolar type II (ATII) cells that secrete surfactant from large secretory vesicles. Surfactant extrusion is facilitated by an actin coat that forms on the vesicle shortly after fusion pore opening. Actin coat compression allows hydrophobic surfactant to be released from the vesicle. We show that microtubules are localized close to actin coats and stay close to the coats during their compression. Inhibition of microtubule polymerization by colchicine and nocodazole affected the kinetics of actin coat formation and the extent of actin polymerisation on fused vesicles. In addition, microtubule and actin cross-linking protein IQGAP1 localized to fused secretory vesicles and IQGAP1 silencing influenced actin polymerisation after vesicle fusion. This study demonstrates that microtubules can influence actin coat formation and actin polymerization on secretory vesicles during exocytosis.
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Affiliation(s)
- M Tabitha Müller
- Institute of General Physiology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | - Rebekka Schempp
- Institute of General Physiology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | - Anngrit Lutz
- Institute of General Physiology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | - Tatiana Felder
- Institute of General Physiology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | - Edward Felder
- Institute of General Physiology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | - Pika Miklavc
- School of Environment and Life Sciences, University of Salford, The Crescent, M54WT, Salford, United Kingdom.
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16
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Shutova MS, Svitkina TM. Common and Specific Functions of Nonmuscle Myosin II Paralogs in Cells. BIOCHEMISTRY (MOSCOW) 2019; 83:1459-1468. [PMID: 30878021 DOI: 10.1134/s0006297918120040] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Various forms of cell motility critically depend on pushing, pulling, and resistance forces generated by the actin cytoskeleton. Whereas pushing forces largely depend on actin polymerization, pulling forces responsible for cell contractility and resistance forces maintaining the cell shape require interaction of actin filaments with the multivalent molecular motor myosin II. In contrast to muscle-specific myosin II paralogs, nonmuscle myosin II (NMII) functions in virtually all mammalian cells, where it executes numerous mechanical tasks. NMII is expressed in mammalian cells as a tissue-specific combination of three paralogs, NMIIA, NMIIB, and NMIIC. Despite overall similarity, these paralogs differ in their molecular properties, which allow them to play both unique and common roles. Importantly, the three paralogs can also cooperate with each other by mixing and matching their unique capabilities. Through specialization and cooperation, NMII paralogs together execute a great variety of tasks in many different cell types. Here, we focus on mammalian NMII paralogs and review novel aspects of their kinetics, regulation, and functions in cells from the perspective of how distinct features of the three myosin II paralogs adapt them to perform specialized and joint tasks in the cells.
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Affiliation(s)
- M S Shutova
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - T M Svitkina
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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17
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Mietkowska M, Schuberth C, Wedlich-Söldner R, Gerke V. Actin dynamics during Ca 2+-dependent exocytosis of endothelial Weibel-Palade bodies. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:1218-1229. [PMID: 30465794 DOI: 10.1016/j.bbamcr.2018.11.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/14/2018] [Accepted: 11/15/2018] [Indexed: 01/24/2023]
Abstract
Weibel-Palade bodies (WPBs) are specialized secretory organelles of endothelial cells that serve important functions in the response to inflammation and vascular injury. WPBs actively respond to different stimuli by regulated exocytosis leading to full or selective release of their contents. Cellular conditions and mechanisms that distinguish between these possibilities are only beginning to emerge. To address this we analyzed dynamic rearrangements of the actin cytoskeleton during histamine-stimulated, Ca2+-dependent WPB exocytosis. We show that most WPB fusion events are followed by a rapid release of von-Willebrand factor (VWF), the large WPB cargo, and that this occurs concomitant with a softening of the actin cortex by the recently described Ca2+-dependent actin reset (CaAR). However, a considerable fraction of WPB fusion events is characterized by a delayed release of VWF and observed after the CaAR reaction peak. These delayed VWF secretions are accompanied by an assembly of actin rings or coats around the WPB post-fusion structures and are also seen following direct elevation of intracellular Ca2+ by plasma membrane wounding. Actin ring/coat assembly at WPB post-fusion structures requires Rho GTPase activity and is significantly reduced upon expression of a dominant-active mutant of the formin INF2 that triggers a permanent CaAR peak-like sequestration of actin to the endoplasmic reticulum. These findings suggest that a rigid actin cortex correlates with a higher proportion of fused WPB which assemble actin rings/coats most likely required for efficient VWF expulsion and/or stabilization of a WPB post-fusion structure. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
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Affiliation(s)
- Magdalena Mietkowska
- Institute of Medical Biochemistry, Centre for Molecular Biology of Inflammation and Cells-in-Motion Cluster of Excellence, University of Münster, Germany
| | - Christian Schuberth
- Institute of Cell Dynamics and Imaging, Centre for Molecular Biology of Inflammation and Cells-in-Motion Cluster of Excellence, University of Münster, Germany
| | - Roland Wedlich-Söldner
- Institute of Cell Dynamics and Imaging, Centre for Molecular Biology of Inflammation and Cells-in-Motion Cluster of Excellence, University of Münster, Germany
| | - Volker Gerke
- Institute of Medical Biochemistry, Centre for Molecular Biology of Inflammation and Cells-in-Motion Cluster of Excellence, University of Münster, Germany.
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18
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Parreno J, Fowler VM. Multifunctional roles of tropomodulin-3 in regulating actin dynamics. Biophys Rev 2018; 10:1605-1615. [PMID: 30430457 DOI: 10.1007/s12551-018-0481-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 11/08/2018] [Indexed: 12/12/2022] Open
Abstract
Tropomodulins (Tmods) are proteins that cap the slow-growing (pointed) ends of actin filaments (F-actin). The basis for our current understanding of Tmod function comes from studies in cells with relatively stable and highly organized F-actin networks, leading to the view that Tmod capping functions principally to preserve F-actin stability. However, not only is Tmod capping dynamic, but it also can play major roles in regulating diverse cellular processes involving F-actin remodeling. Here, we highlight the multifunctional roles of Tmod with a focus on Tmod3. Like other Tmods, Tmod3 binds tropomyosin (Tpm) and actin, capping pure F-actin at submicromolar and Tpm-coated F-actin at nanomolar concentrations. Unlike other Tmods, Tmod3 can also bind actin monomers and its ability to bind actin is inhibited by phosphorylation of Tmod3 by Akt2. Tmod3 is ubiquitously expressed and is present in a diverse array of cytoskeletal structures, including contractile structures such as sarcomere-like units of actomyosin stress fibers and in the F-actin network encompassing adherens junctions. Tmod3 participates in F-actin network remodeling in lamellipodia during cell migration and in the assembly of specialized F-actin networks during exocytosis. Furthermore, Tmod3 is required for development, regulating F-actin mesh formation during meiosis I of mouse oocytes, erythroblast enucleation in definitive erythropoiesis, and megakaryocyte morphogenesis in the mouse fetal liver. Thus, Tmod3 plays vital roles in dynamic and stable F-actin networks in cell physiology and development, with further research required to delineate the mechanistic details of Tmod3 regulation in the aforementioned processes, or in other yet to be discovered processes.
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Affiliation(s)
- Justin Parreno
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Velia M Fowler
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA, 92037, USA.
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19
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Actin Remodeling in Regulated Exocytosis: Toward a Mesoscopic View. Trends Cell Biol 2018; 28:685-697. [DOI: 10.1016/j.tcb.2018.04.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 04/05/2018] [Accepted: 04/13/2018] [Indexed: 01/10/2023]
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20
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Zhang J, Li Q, Shao Q, Song J, Zhou B, Shu P. Effects of panax notoginseng saponin on the pathological ultrastructure and serum IL‐6 and IL‐8 in pulmonary fibrosis in rabbits. J Cell Biochem 2018; 119:8410-8418. [DOI: 10.1002/jcb.27045] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 04/23/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Jizhou Zhang
- Department of OncologyWenzhou Traditional Chinese Medicine Affiliated to Zhejiang Chinese Medicine UniversityWenzhouZhejiangChina
| | - Qing Li
- Department of Integrated TCM & Western MedicineThe Second Affiliated Hospital of Kunming Medical CollegeKunmingYunnanChina
| | - Qiqi Shao
- Department of NursingWenzhou Lucheng District Wuma Community Health Service CenterWenzhouZhejiangChina
| | - Jingling Song
- Teaching and Research Section of PathologyKunming Medical UniversityKunmingYunnanChina
| | - Bin Zhou
- Department of OncologyWenzhou Traditional Chinese Medicine Affiliated to Zhejiang Chinese Medicine UniversityWenzhouZhejiangChina
| | - Peng Shu
- Department of OncologyJiangsu Province Hospital of TCMNanjingJiangsuChina
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21
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Segal D, Zaritsky A, Schejter ED, Shilo BZ. Feedback inhibition of actin on Rho mediates content release from large secretory vesicles. J Cell Biol 2018; 217:1815-1826. [PMID: 29496739 PMCID: PMC5940311 DOI: 10.1083/jcb.201711006] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 12/24/2017] [Accepted: 01/30/2018] [Indexed: 12/02/2022] Open
Abstract
Secretion of adhesive glycoproteins to the lumen of Drosophila melanogaster larval salivary glands is performed by contraction of an actomyosin network assembled around large secretory vesicles, after their fusion to the apical membranes. We have identified a cycle of actin coat nucleation and disassembly that is independent of myosin. Recruitment of active Rho1 to the fused vesicle triggers activation of the formin Diaphanous and actin nucleation. This leads to actin-dependent localization of a RhoGAP protein that locally shuts off Rho1, promoting disassembly of the actin coat. When contraction of vesicles is blocked, the strict temporal order of the recruited elements generates repeated oscillations of actin coat formation and disassembly. Interestingly, different blocks to actin coat disassembly arrested vesicle contraction, indicating that actin turnover is an integral part of the actomyosin contraction cycle. The capacity of F-actin to trigger a negative feedback on its own production may be widely used to coordinate a succession of morphogenetic events or maintain homeostasis.
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Affiliation(s)
- Dagan Segal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Assaf Zaritsky
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Eyal D Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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22
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Varjabedian A, Kita A, Bement W. Living Xenopus oocytes, eggs, and embryos as models for cell division. Methods Cell Biol 2018; 144:259-285. [PMID: 29804672 PMCID: PMC6050073 DOI: 10.1016/bs.mcb.2018.03.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Xenopus laevis has long been a popular model for studies of development and, based on the use of cell-free extracts derived from its eggs, as a model for reconstitution of cell cycle regulation and other basic cellular processes. However, work over the last several years has shown that intact Xenopus eggs and embryos are also powerful models for visualization and characterization of cell cycle-regulated cytoskeletal dynamics. These findings were something of a surprise, given that the relatively low opacity of Xenopus eggs and embryos was assumed to make them poor subjects for live-cell imaging. In fact, however, the high tolerance for light exposure, the development of new imaging approaches, new probes for cytoskeletal components and cytoskeletal regulators, and the ease of microinjection make the Xenopus oocytes, eggs, and embryos one of the most useful live-cell imaging models among the vertebrates. In this review, we describe the basics of using X. laevis as a model organism for studying cell division and outline experimental approaches for imaging cytoskeletal components in vivo in X. laevis embryos and eggs.
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Affiliation(s)
- Ani Varjabedian
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI, United States; Graduate Program in Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI, United States
| | - Angela Kita
- Graduate Program in Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI, United States; Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, United States
| | - William Bement
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI, United States; Graduate Program in Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI, United States; Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, United States.
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23
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Polyisoprenylated cysteinyl amide inhibitors disrupt actin cytoskeleton organization, induce cell rounding and block migration of non-small cell lung cancer. Oncotarget 2018; 8:31726-31744. [PMID: 28423648 PMCID: PMC5458243 DOI: 10.18632/oncotarget.15956] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 02/15/2017] [Indexed: 12/18/2022] Open
Abstract
The malignant potential of Non-Small Cell Lung Cancer (NSCLC) is dependent on cellular processes that promote metastasis. F-actin organization is central to cell migration, invasion, adhesion and angiogenesis, processes involved in metastasis. F-actin remodeling is enhanced by the overexpression and/or hyper-activation of some members of the Rho family of small GTPases. Therefore, agents that mitigate hyperactive Rho proteins may be relevant for controlling metastasis. We previously reported the role of polyisoprenylated cysteinyl amide inhibitors (PCAIs) as potential inhibitors of cancers with hyperactive small GTPases. In this report, we investigate the potential role of PCAIs against NSCLC cells and show that as low as 0.5 μM PCAIs significantly inhibit 2D and 3D NCI-H1299 cell migration by 48% and 45%, respectively. PCAIs at 1 μM inhibited 2D and 3D NCI-H1299 cell invasion through Matrigel by 50% and 85%, respectively. Additionally, exposure to 5 μM of the PCAIs for 24 h caused at least a 66% drop in the levels of Rac1, Cdc42, and RhoA and a 38% drop in F-actin intensity at the cell membrane. This drop in F-actin was accompanied by a 73% reduction in the number of filopodia per cell. Interestingly, the polyisoprenyl group of the PCAIs is essential for these effects, as NSL-100, a non-farnesylated analog, does not elicit similar effects on F-actin assembly and organization. Our findings indicate that PCAIs disrupt F-actin assembly and organization to suppress cell motility and invasion. The PCAIs may be an effective therapy option for NSCLC metastasis and invasion control.
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24
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Masedunskas A, Appaduray MA, Lucas CA, Lastra Cagigas M, Heydecker M, Holliday M, Meiring JCM, Hook J, Kee A, White M, Thomas P, Zhang Y, Adelstein RS, Meckel T, Böcking T, Weigert R, Bryce NS, Gunning PW, Hardeman EC. Parallel assembly of actin and tropomyosin, but not myosin II, during de novo actin filament formation in live mice. J Cell Sci 2018; 131:jcs.212654. [PMID: 29487177 DOI: 10.1242/jcs.212654] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 02/12/2018] [Indexed: 01/04/2023] Open
Abstract
Many actin filaments in animal cells are co-polymers of actin and tropomyosin. In many cases, non-muscle myosin II associates with these co-polymers to establish a contractile network. However, the temporal relationship of these three proteins in the de novo assembly of actin filaments is not known. Intravital subcellular microscopy of secretory granule exocytosis allows the visualisation and quantification of the formation of an actin scaffold in real time, with the added advantage that it occurs in a living mammal under physiological conditions. We used this model system to investigate the de novo assembly of actin, tropomyosin Tpm3.1 (a short isoform of TPM3) and myosin IIA (the form of non-muscle myosin II with its heavy chain encoded by Myh9) on secretory granules in mouse salivary glands. Blocking actin polymerization with cytochalasin D revealed that Tpm3.1 assembly is dependent on actin assembly. We used time-lapse imaging to determine the timing of the appearance of the actin filament reporter LifeAct-RFP and of Tpm3.1-mNeonGreen on secretory granules in LifeAct-RFP transgenic, Tpm3.1-mNeonGreen and myosin IIA-GFP (GFP-tagged MYH9) knock-in mice. Our findings are consistent with the addition of tropomyosin to actin filaments shortly after the initiation of actin filament nucleation, followed by myosin IIA recruitment.
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Affiliation(s)
| | | | | | | | - Marco Heydecker
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia.,Membrane Dynamics, Department of Biology, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287 Darmstadt, Germany
| | - Mira Holliday
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia
| | | | - Jeff Hook
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia
| | - Anthony Kee
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia
| | - Melissa White
- South Australian Genome Editing, Facility Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia
| | - Paul Thomas
- South Australian Genome Editing, Facility Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia
| | - Yingfan Zhang
- NHLBI, National Institutes of Health, Bethesda, MD 20892, USA
| | | | - Tobias Meckel
- Membrane Dynamics, Department of Biology, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287 Darmstadt, Germany
| | - Till Böcking
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia
| | - Roberto Weigert
- Laboratory of Cellular and Molecular Biology, CCR, National Cancer Institute, Bethesda, MD 20892, USA
| | - Nicole S Bryce
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia
| | - Peter W Gunning
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia
| | - Edna C Hardeman
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia
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25
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Shutova MS, Svitkina TM. Mammalian nonmuscle myosin II comes in three flavors. Biochem Biophys Res Commun 2018; 506:394-402. [PMID: 29550471 DOI: 10.1016/j.bbrc.2018.03.103] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 03/13/2018] [Indexed: 12/16/2022]
Abstract
Nonmuscle myosin II is an actin-based motor that executes numerous mechanical tasks in cells including spatiotemporal organization of the actin cytoskeleton, adhesion, migration, cytokinesis, tissue remodeling, and membrane trafficking. Nonmuscle myosin II is ubiquitously expressed in mammalian cells as a tissue-specific combination of three paralogs. Recent studies reveal novel specific aspects of their kinetics, intracellular regulation and functions. On the other hand, the three paralogs also can copolymerize and cooperate in cells. Here we review the recent advances from the prospective of how distinct features of the three myosin II paralogs adapt them to perform specialized and joint tasks in the cell.
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Affiliation(s)
- Maria S Shutova
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Tatyana M Svitkina
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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26
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Abstract
Murrell-Lagnado provides insight into new research revealing the physiological role of lysosomal P2X4 channels.
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Affiliation(s)
- Ruth D Murrell-Lagnado
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, England, UK
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27
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Fois G, Winkelmann VE, Bareis L, Staudenmaier L, Hecht E, Ziller C, Ehinger K, Schymeinsky J, Kranz C, Frick M. ATP is stored in lamellar bodies to activate vesicular P2X 4 in an autocrine fashion upon exocytosis. J Gen Physiol 2017; 150:277-291. [PMID: 29282210 PMCID: PMC5806682 DOI: 10.1085/jgp.201711870] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 10/12/2017] [Accepted: 11/17/2017] [Indexed: 12/14/2022] Open
Abstract
P2X4 receptor activation facilitates secretion of pulmonary surfactant from secretory vesicles called lamellar bodies in alveolar epithelial cells. Fois et al. reveal that P2X4 receptors on the lamellar body membranes are activated by ATP stored within the vesicles themselves upon vesicle exocytosis. Vesicular P2X4 receptors are known to facilitate secretion and activation of pulmonary surfactant in the alveoli of the lungs. P2X4 receptors are expressed in the membrane of lamellar bodies (LBs), large secretory lysosomes that store lung surfactant in alveolar type II epithelial cells, and become inserted into the plasma membrane after exocytosis. Subsequent activation of P2X4 receptors by adenosine triphosphate (ATP) results in local fusion-activated cation entry (FACE), facilitating fusion pore dilation, surfactant secretion, and surfactant activation. Despite the importance of ATP in the alveoli, and hence lung function, the origin of ATP in the alveoli is still elusive. In this study, we demonstrate that ATP is stored within LBs themselves at a concentration of ∼1.9 mM. ATP is loaded into LBs by the vesicular nucleotide transporter but does not activate P2X4 receptors because of the low intraluminal pH (5.5). However, the rise in intravesicular pH after opening of the exocytic fusion pore results in immediate activation of vesicular P2X4 by vesicular ATP. Our data suggest a new model in which agonist (ATP) and receptor (P2X4) are located in the same intracellular compartment (LB), protected from premature degradation (ATP) and activation (P2X4), and ideally placed to ensure coordinated and timely receptor activation as soon as fusion occurs to facilitate surfactant secretion.
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Affiliation(s)
- Giorgio Fois
- Institute of General Physiology, Ulm University, Ulm, Germany
| | | | - Lara Bareis
- Institute of General Physiology, Ulm University, Ulm, Germany
| | | | - Elena Hecht
- Institute of General Physiology, Ulm University, Ulm, Germany
| | - Charlotte Ziller
- Institute of Analytical and Bioanalytical Chemistry, Ulm University, Ulm, Germany
| | | | - Jürgen Schymeinsky
- Immunology and Respiratory Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riß, Germany
| | - Christine Kranz
- Institute of Analytical and Bioanalytical Chemistry, Ulm University, Ulm, Germany
| | - Manfred Frick
- Institute of General Physiology, Ulm University, Ulm, Germany
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28
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Myosin IIa is critical for cAMP-mediated endothelial secretion of von Willebrand factor. Blood 2017; 131:686-698. [PMID: 29208598 DOI: 10.1182/blood-2017-08-802140] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 11/14/2017] [Indexed: 01/10/2023] Open
Abstract
Nonmuscle myosin II has been implicated in regulation of von Willebrand factor (VWF) release from endothelial Weibel-Palade bodies (WPBs), but the specific role of myosin IIa isoform is poorly defined. Here, we report that myosin IIa is expressed both in primary human endothelial cells and intact mouse vessels, essential for cyclic adenosine monophosphate (cAMP)-mediated endothelial VWF secretion. Downregulation of myosin IIa by shRNAs significantly suppressed both forskolin- and epinephrine-induced VWF secretion. Endothelium-specific myosin IIa knockout mice exhibited impaired epinephrine-stimulated VWF release, prolonged bleeding time, and thrombosis. Further study showed that in resting cells, myosin IIa deficiency disrupted the peripheral localization of Rab27-positive WPBs along stress fibers; on stimulation by cAMP agonists, myosin IIa in synergy with zyxin promotes the formation of a functional actin framework, which is derived from preexisting cortical actin filaments, around WPBs, facilitating fusion and subsequent exocytosis. In summary, our findings not only identify new functions of myosin IIa in regulation of WPB positioning and the interaction between preexisting cortical actin filaments and exocytosing vesicles before fusion but also reveal myosin IIa as a physiological regulator of endothelial VWF secretion in stress-induced hemostasis and thrombosis.
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29
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Yamamoto Y, Gotoh S, Korogi Y, Seki M, Konishi S, Ikeo S, Sone N, Nagasaki T, Matsumoto H, Muro S, Ito I, Hirai T, Kohno T, Suzuki Y, Mishima M. Long-term expansion of alveolar stem cells derived from human iPS cells in organoids. Nat Methods 2017; 14:1097-1106. [DOI: 10.1038/nmeth.4448] [Citation(s) in RCA: 139] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 08/13/2017] [Indexed: 12/19/2022]
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30
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Milberg O, Shitara A, Ebrahim S, Masedunskas A, Tora M, Tran DT, Chen Y, Conti MA, Adelstein RS, Ten Hagen KG, Weigert R. Concerted actions of distinct nonmuscle myosin II isoforms drive intracellular membrane remodeling in live animals. J Cell Biol 2017; 216:1925-1936. [PMID: 28600434 PMCID: PMC5496622 DOI: 10.1083/jcb.201612126] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 04/02/2017] [Accepted: 05/02/2017] [Indexed: 12/11/2022] Open
Abstract
Membrane remodeling plays a fundamental role during a variety of biological events. However, the dynamics and the molecular mechanisms regulating this process within cells in mammalian tissues in situ remain largely unknown. In this study, we use intravital subcellular microscopy in live mice to study the role of the actomyosin cytoskeleton in driving the remodeling of membranes of large secretory granules, which are integrated into the plasma membrane during regulated exocytosis. We show that two isoforms of nonmuscle myosin II, NMIIA and NMIIB, control distinct steps of the integration process. Furthermore, we find that F-actin is not essential for the recruitment of NMII to the secretory granules but plays a key role in the assembly and activation of NMII into contractile filaments. Our data support a dual role for the actomyosin cytoskeleton in providing the mechanical forces required to remodel the lipid bilayer and serving as a scaffold to recruit key regulatory molecules.
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Affiliation(s)
- Oleg Milberg
- Intracellular Membrane Trafficking Section, National Institutes of Health, Bethesda, MD
| | - Akiko Shitara
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD.,Intracellular Membrane Trafficking Section, National Institutes of Health, Bethesda, MD
| | - Seham Ebrahim
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Andrius Masedunskas
- Intracellular Membrane Trafficking Section, National Institutes of Health, Bethesda, MD.,School of Medical Sciences, University of New South Wales, Sidney, Australia
| | - Muhibullah Tora
- Intracellular Membrane Trafficking Section, National Institutes of Health, Bethesda, MD
| | - Duy T Tran
- Developmental Glycobiology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD
| | - Yun Chen
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Mary Anne Conti
- Laboratory of Molecular Cardiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Robert S Adelstein
- Laboratory of Molecular Cardiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Kelly G Ten Hagen
- Developmental Glycobiology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD
| | - Roberto Weigert
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD .,Intracellular Membrane Trafficking Section, National Institutes of Health, Bethesda, MD
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31
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Brown K, Filuta A, Ludwig MG, Seuwen K, Jaros J, Vidal S, Arora K, Naren AP, Kandasamy K, Parthasarathi K, Offermanns S, Mason RJ, Miller WE, Whitsett JA, Bridges JP. Epithelial Gpr116 regulates pulmonary alveolar homeostasis via Gq/11 signaling. JCI Insight 2017; 2:93700. [PMID: 28570277 DOI: 10.1172/jci.insight.93700] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 05/02/2017] [Indexed: 12/27/2022] Open
Abstract
Pulmonary function is dependent upon the precise regulation of alveolar surfactant. Alterations in pulmonary surfactant concentrations or function impair ventilation and cause tissue injury. Identification of the molecular pathways that sense and regulate endogenous alveolar surfactant concentrations, coupled with the ability to pharmacologically modulate them both positively and negatively, would be a major therapeutic advance for patients with acute and chronic lung diseases caused by disruption of surfactant homeostasis. The orphan adhesion GPCR GPR116 (also known as Adgrf5) is a critical regulator of alveolar surfactant concentrations. Here, we show that human and mouse GPR116 control surfactant secretion and reuptake in alveolar type II (AT2) cells by regulating guanine nucleotide-binding domain α q and 11 (Gq/11) signaling. Synthetic peptides derived from the ectodomain of GPR116 activated Gq/11-dependent inositol phosphate conversion, calcium mobilization, and cortical F-actin stabilization to inhibit surfactant secretion. AT2 cell-specific deletion of Gnaq and Gna11 phenocopied the accumulation of surfactant observed in Gpr116-/- mice. These data provide proof of concept that GPR116 is a plausible therapeutic target to modulate endogenous alveolar surfactant pools to treat pulmonary diseases associated with surfactant dysfunction.
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Affiliation(s)
- Kari Brown
- Department of Pediatrics, Perinatal Institute, Section of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Alyssa Filuta
- Department of Pediatrics, Perinatal Institute, Section of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | | | - Klaus Seuwen
- Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Julian Jaros
- Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Solange Vidal
- Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Kavisha Arora
- Department of Pediatrics, Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Anjaparavanda P Naren
- Department of Pediatrics, Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Kathirvel Kandasamy
- Department of Physiology, University of Tennessee Health Sciences Center, Memphis, Tennessee, USA
| | - Kaushik Parthasarathi
- Department of Physiology, University of Tennessee Health Sciences Center, Memphis, Tennessee, USA
| | - Stefan Offermanns
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Robert J Mason
- Department of Medicine, National Jewish Health, Denver, Colorado, USA
| | - William E Miller
- Department of Molecular Genetics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Jeffrey A Whitsett
- Department of Pediatrics, Perinatal Institute, Section of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - James P Bridges
- Department of Pediatrics, Perinatal Institute, Section of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
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32
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Abstract
Real-time imaging of regulated exocytosis in secreting organs can provide unprecedented temporal and spatial detail. Here, we highlight recent advances in 3D time-lapse imaging in Drosophila salivary glands at single-granule resolution. Using fluorescently labeled proteins expressed in the fly, it is now possible to image the dynamics of vesicle biogenesis and the cytoskeletal factors involved in secretion. 3D imaging over time allows one to visualize and define the temporal sequence of events, including clearance of cortical actin, fusion pore formation, mixing of the vesicular and plasma membranes and recruitment of components of the cytoskeleton. We will also discuss the genetic tools available in the fly that allow one to interrogate the essential factors involved in secretory vesicle formation, cargo secretion and the ultimate integration of the vesicular and plasma membranes. We argue that the combination of high-resolution real-time imaging and powerful genetics provides a platform to investigate the role of any factor in regulated secretion.
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Affiliation(s)
- Duy T Tran
- Section on Biological Chemistry, NIDCR, National Institutes of Health, 30 Convent Drive, Bethesda, MD 20892, USA
| | - Kelly G Ten Hagen
- Developmental Glycobiology Section, NIDCR, National Institutes of Health, 30 Convent Drive, Bethesda, MD 20892, USA
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33
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Olmeda B, Martínez-Calle M, Pérez-Gil J. Pulmonary surfactant metabolism in the alveolar airspace: Biogenesis, extracellular conversions, recycling. Ann Anat 2016; 209:78-92. [PMID: 27773772 DOI: 10.1016/j.aanat.2016.09.008] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/22/2016] [Accepted: 09/25/2016] [Indexed: 01/03/2023]
Abstract
Pulmonary surfactant is a lipid-protein complex that lines and stabilizes the respiratory interface in the alveoli, allowing for gas exchange during the breathing cycle. At the same time, surfactant constitutes the first line of lung defense against pathogens. This review presents an updated view on the processes involved in biogenesis and intracellular processing of newly synthesized and recycled surfactant components, as well as on the extracellular surfactant transformations before and after the formation of the surface active film at the air-water interface. Special attention is paid to the crucial regulation of surfactant homeostasis, because its disruption is associated with several lung pathologies.
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Affiliation(s)
- Bárbara Olmeda
- Department of Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, 28040 Madrid, Spain
| | - Marta Martínez-Calle
- Department of Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, 28040 Madrid, Spain
| | - Jesus Pérez-Gil
- Department of Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, 28040 Madrid, Spain.
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34
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Li M, Xiao X, Liu L, Xi N, Wang Y. Nanoscale Quantifying the Effects of Targeted Drug on Chemotherapy in Lymphoma Treatment Using Atomic Force Microscopy. IEEE Trans Biomed Eng 2016; 63:2187-99. [DOI: 10.1109/tbme.2015.2512924] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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35
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Hobi N, Giolai M, Olmeda B, Miklavc P, Felder E, Walther P, Dietl P, Frick M, Pérez-Gil J, Haller T. A small key unlocks a heavy door: The essential function of the small hydrophobic proteins SP-B and SP-C to trigger adsorption of pulmonary surfactant lamellar bodies. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2124-34. [DOI: 10.1016/j.bbamcr.2016.04.028] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 04/15/2016] [Accepted: 04/27/2016] [Indexed: 02/07/2023]
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36
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Abstract
An actin filament coat promotes cargo expulsion from large exocytosing vesicles, but the mechanisms of coat formation and force generation have been poorly characterized. Elegant imaging studies of the Drosophila melanogaster salivary gland now reveal how actin and myosin are recruited, and show that myosin II forms a contractile 'cage' that facilitates exocytosis.
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Affiliation(s)
- Christien J Merrifield
- Institute for Integrative Biology of the Cell, Bât. 34, Avenue de la Terrasse, 9198 Gif sur Yvette cedex, France
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37
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Gabel M, Chasserot-Golaz S. Annexin A2, an essential partner of the exocytotic process in chromaffin cells. J Neurochem 2016; 137:890-6. [DOI: 10.1111/jnc.13628] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 03/09/2016] [Accepted: 03/30/2016] [Indexed: 12/30/2022]
Affiliation(s)
- Marion Gabel
- INCI; UPR3212 CNRS; Université de Strasbourg; Strasbourg France
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38
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Kittelberger N, Breunig M, Martin R, Knölker HJ, Miklavc P. The role of myosin 1c and myosin 1b in surfactant exocytosis. J Cell Sci 2016; 129:1685-96. [PMID: 26940917 PMCID: PMC4852769 DOI: 10.1242/jcs.181313] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 02/25/2016] [Indexed: 12/19/2022] Open
Abstract
Actin and actin-associated proteins have a pivotal effect on regulated exocytosis in secretory cells and influence pre-fusion as well as post-fusion stages of exocytosis. Actin polymerization on secretory granules during the post-fusion phase (formation of an actin coat) is especially important in cells with large secretory vesicles or poorly soluble secretions. Alveolar type II (ATII) cells secrete hydrophobic lipo-protein surfactant, which does not easily diffuse from fused vesicles. Previous work showed that compression of actin coat is necessary for surfactant extrusion. Here, we investigate the role of class 1 myosins as possible linkers between actin and membranes during exocytosis. Live-cell microscopy showed translocation of fluorescently labeled myosin 1b and myosin 1c to the secretory vesicle membrane after fusion. Myosin 1c translocation was dependent on its pleckstrin homology domain. Expression of myosin 1b and myosin 1c constructs influenced vesicle compression rate, whereas only the inhibition of myosin 1c reduced exocytosis. These findings suggest that class 1 myosins participate in several stages of ATII cell exocytosis and link actin coats to the secretory vesicle membrane to influence vesicle compression.
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Affiliation(s)
- Nadine Kittelberger
- Institute of General Physiology, Ulm University, Albert-Einstein Allee 11, Ulm 89081, Germany
| | - Markus Breunig
- Institute of General Physiology, Ulm University, Albert-Einstein Allee 11, Ulm 89081, Germany
| | - René Martin
- Department of Chemistry, Technische Universität Dresden, Bergstr. 66, Dresden 01069, Germany
| | - Hans-Joachim Knölker
- Department of Chemistry, Technische Universität Dresden, Bergstr. 66, Dresden 01069, Germany
| | - Pika Miklavc
- Institute of General Physiology, Ulm University, Albert-Einstein Allee 11, Ulm 89081, Germany
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39
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Gabel M, Delavoie F, Demais V, Royer C, Bailly Y, Vitale N, Bader MF, Chasserot-Golaz S. Annexin A2-dependent actin bundling promotes secretory granule docking to the plasma membrane and exocytosis. J Cell Biol 2015; 210:785-800. [PMID: 26323692 PMCID: PMC4555831 DOI: 10.1083/jcb.201412030] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Annexin A2, a calcium-, actin-, and lipid-binding protein involved in exocytosis, mediates the formation of lipid microdomains required for the structural and spatial organization of fusion sites at the plasma membrane. To understand how annexin A2 promotes this membrane remodeling, the involvement of cortical actin filaments in lipid domain organization was investigated. 3D electron tomography showed that cortical actin bundled by annexin A2 connected docked secretory granules to the plasma membrane and contributed to the formation of GM1-enriched lipid microdomains at the exocytotic sites in chromaffin cells. When an annexin A2 mutant with impaired actin filament-bundling activity was expressed, the formation of plasma membrane lipid microdomains and the number of exocytotic events were decreased and the fusion kinetics were slower, whereas the pharmacological activation of the intrinsic actin-bundling activity of endogenous annexin A2 had the opposite effects. Thus, annexin A2-induced actin bundling is apparently essential for generating active exocytotic sites.
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Affiliation(s)
- Marion Gabel
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 Centre National de la Recherche Scientifique, Université de Strasbourg, F-67084 Strasbourg, France
| | - Franck Delavoie
- Laboratoire de Biologie Moléculaire Eucaryote, UMR5099 Centre National de la Recherche Scientifique-Université de Toulouse III Paul Sabatier, F-31000 Toulouse, France
| | - Valérie Demais
- Plateforme Imagerie In Vitro, Neuropôle de Strasbourg, F-67084 Strasbourg, France
| | - Cathy Royer
- Plateforme Imagerie In Vitro, Neuropôle de Strasbourg, F-67084 Strasbourg, France
| | - Yannick Bailly
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 Centre National de la Recherche Scientifique, Université de Strasbourg, F-67084 Strasbourg, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 Centre National de la Recherche Scientifique, Université de Strasbourg, F-67084 Strasbourg, France
| | - Marie-France Bader
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 Centre National de la Recherche Scientifique, Université de Strasbourg, F-67084 Strasbourg, France
| | - Sylvette Chasserot-Golaz
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 Centre National de la Recherche Scientifique, Université de Strasbourg, F-67084 Strasbourg, France
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40
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Arp2/3-mediated F-actin formation controls regulated exocytosis in vivo. Nat Commun 2015; 6:10098. [PMID: 26639106 PMCID: PMC4686765 DOI: 10.1038/ncomms10098] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 11/02/2015] [Indexed: 02/07/2023] Open
Abstract
The actin cytoskeleton plays crucial roles in many cellular processes, including regulated secretion. However, the mechanisms controlling F-actin dynamics in this process are largely unknown. Through 3D time-lapse imaging in a secreting organ, we show that F-actin is actively disassembled along the apical plasma membrane at the site of secretory vesicle fusion and re-assembled directionally on vesicle membranes. Moreover, we show that fusion pore formation and PIP2 redistribution precedes actin and myosin recruitment to secretory vesicle membranes. Finally, we show essential roles for the branched actin nucleators Arp2/3- and WASp in the process of secretory cargo expulsion and integration of vesicular membranes with the apical plasma membrane. Our results highlight previously unknown roles for branched actin in exocytosis and provide a genetically tractable system to image the temporal and spatial dynamics of polarized secretion in vivo. The cytoskeleton plays a crucial role in secretion. Here Tran et al. demonstrate that cortical actin is rearranged at the site of vesicle fusion and recruited to fused secretory granules in Drosophila salivary glands, and show that branched actin nucleators are required for cargo expulsion.
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41
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Orchestrated content release from Drosophila glue-protein vesicles by a contractile actomyosin network. Nat Cell Biol 2015; 18:181-90. [DOI: 10.1038/ncb3288] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 11/11/2015] [Indexed: 12/22/2022]
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42
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Szumowski SC, Estes KA, Popovich JJ, Botts MR, Sek G, Troemel ER. Small GTPases promote actin coat formation on microsporidian pathogens traversing the apical membrane of Caenorhabditis elegans intestinal cells. Cell Microbiol 2015; 18:30-45. [PMID: 26147591 DOI: 10.1111/cmi.12481] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 06/01/2015] [Accepted: 06/12/2015] [Indexed: 12/16/2022]
Abstract
Many intracellular pathogens co-opt actin in host cells, but little is known about these interactions in vivo. We study the in vivo trafficking and exit of the microsporidian Nematocida parisii, which is an intracellular pathogen that infects intestinal cells of the nematode Caenorhabditis elegans. We recently demonstrated that N. parisii uses directional exocytosis to escape out of intestinal cells into the intestinal tract. Here, we show that an intestinal-specific isoform of C. elegans actin called ACT-5 forms coats around membrane compartments that contain single exocytosing spores, and that these coats appear to form after fusion with the apical membrane. We performed a genetic screen for host factors required for actin coat formation and identified small GTPases important for this process. Through analysis of animals defective in these factors, we found that actin coats are not required for pathogen exit although they may boost exocytic output. Later during infection, we find that ACT-5 also forms coats around membrane-bound vesicles that contain multiple spores. These vesicles are likely formed by clathrin-dependent compensatory endocytosis to retrieve membrane material that has been trafficked to the apical membrane as part of the exocytosis process. These findings provide insight into microsporidia interaction with host cells, and provide novel in vivo examples of the manner in which intracellular pathogens co-opt host actin during their life cycle.
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Affiliation(s)
- Suzannah C Szumowski
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, La Jolla, CA, USA
| | - Kathleen A Estes
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, La Jolla, CA, USA
| | - John J Popovich
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, La Jolla, CA, USA
| | - Michael R Botts
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, La Jolla, CA, USA
| | - Grace Sek
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, La Jolla, CA, USA
| | - Emily R Troemel
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, La Jolla, CA, USA
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43
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Shitara A, Weigert R. Imaging membrane remodeling during regulated exocytosis in live mice. Exp Cell Res 2015; 337:219-25. [PMID: 26160452 DOI: 10.1016/j.yexcr.2015.06.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 06/28/2015] [Indexed: 10/23/2022]
Abstract
In this mini-review we focus on the use of time-lapse light microscopy to study membrane remodeling during protein secretion in live animals. In particular, we highlight how subcellular intravital microscopy has enabled imaging the dynamics of both individual secretory vesicles and the plasma membrane, during different steps in the exocytic process. This powerful approach has provided us with the unique opportunity to unravel the role of the actin cytoskeleton in regulating this process under physiological conditions, and to overcome the shortcomings of more reductionist model systems.
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Affiliation(s)
- Akiko Shitara
- Intracellular Membrane Trafficking Section, Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, 30 Convent Dr. 303A, Bethesda, MD 20892-4340, United States
| | - Roberto Weigert
- Intracellular Membrane Trafficking Section, Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, 30 Convent Dr. 303A, Bethesda, MD 20892-4340, United States.
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SMIFH2 has effects on Formins and p53 that perturb the cell cytoskeleton. Sci Rep 2015; 5:9802. [PMID: 25925024 PMCID: PMC5386218 DOI: 10.1038/srep09802] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 03/19/2015] [Indexed: 01/08/2023] Open
Abstract
Formin proteins are key regulators of the cytoskeleton involved in developmental and homeostatic programs, and human disease. For these reasons, small molecules interfering with Formins' activity have gained increasing attention. Among them, small molecule inhibitor of Formin Homology 2 domains (SMIFH2) is often used as a pharmacological Formin blocker. Although SMIFH2 inhibits actin polymerization by Formins and affects the actin cytoskeleton, its cellular mechanism of action and target specificity remain unclear. Here we show that SMIFH2 induces remodelling of actin filaments, microtubules and the Golgi complex as a result of its effects on Formins and p53. We found that SMIFH2 triggers alternated depolymerization-repolymerization cycles of actin and tubulin, increases cell migration, causes scattering of the Golgi complex, and also cytotoxicity at high dose. Moreover, SMIFH2 reduces expression and activity of p53 through a post-transcriptional, proteasome-independent mechanism that influences remodelling of the cytoskeleton. As the action of SMIFH2 may go beyond Formin inhibition, only short-term and low-dose SMIFH2 treatments minimize confounding effects induced by loss of p53 and cytotoxicity.
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Positively charged amino acids at the SNAP-25 C terminus determine fusion rates, fusion pore properties, and energetics of tight SNARE complex zippering. J Neurosci 2015; 35:3230-9. [PMID: 25698757 DOI: 10.1523/jneurosci.2905-14.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
SNAP-25 is a Q-SNARE protein mediating exocytosis of neurosecretory vesicles including chromaffin granules. Previous results with a SNAP-25 construct lacking the nine C terminal residues (SNAP-25Δ9) showed changed fusion pore properties (Fang et al., 2008), suggesting a model for fusion pore mechanics that couple C terminal zipping of the SNARE complex to the opening of the fusion pore. The deleted fragment contains the positively charged residues R198 and K201, adjacent to layers 7 and 8 of the SNARE complex. To determine how fusion pore conductance and dynamics depend on these residues, single exocytotic events in bovine chromaffin cells expressing R198Q, R198E, K201Q, or K201E mutants were investigated by carbon fiber amperometry and cell-attached patch capacitance measurements. Coarse grain molecular dynamics simulations revealed spontaneous transitions between a loose and tightly zippered state at the SNARE complex C terminus. The SNAP-25 K201Q mutant showed no changes compared with SNAP-25 wild-type. However, K201E, R198Q, and R198E displayed reduced release frequencies, slower release kinetics, and prolonged fusion pore duration that were correlated with reduced probability to engage in the tightly zippered state. The results show that the positively charged amino acids at the SNAP-25 C terminus promote tight SNARE complex zippering and are required for high release frequency and rapid release in individual fusion events.
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Miklavc P, Ehinger K, Sultan A, Felder T, Paul P, Gottschalk KE, Frick M. Actin depolymerisation and crosslinking join forces with myosin II to contract actin coats on fused secretory vesicles. J Cell Sci 2015; 128:1193-203. [PMID: 25637593 PMCID: PMC4359923 DOI: 10.1242/jcs.165571] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
In many secretory cells actin and myosin are specifically recruited to the surface of secretory granules following their fusion with the plasma membrane. Actomyosin-dependent compression of fused granules is essential to promote active extrusion of cargo. However, little is known about molecular mechanisms regulating actin coat formation and contraction. Here, we provide a detailed kinetic analysis of the molecules regulating actin coat contraction on fused lamellar bodies in primary alveolar type II cells. We demonstrate that ROCK1 and myosin light chain kinase 1 (MLCK1, also known as MYLK) translocate to fused lamellar bodies and activate myosin II on actin coats. However, myosin II activity is not sufficient for efficient actin coat contraction. In addition, cofilin-1 and α-actinin translocate to actin coats. ROCK1-dependent regulated actin depolymerisation by cofilin-1 in cooperation with actin crosslinking by α-actinin is essential for complete coat contraction. In summary, our data suggest a complementary role for regulated actin depolymerisation and crosslinking, and myosin II activity, to contract actin coats and drive secretion.
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Affiliation(s)
- Pika Miklavc
- Department of General Physiology, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
| | - Konstantin Ehinger
- Department of General Physiology, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
| | - Ayesha Sultan
- Department of General Physiology, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
| | - Tatiana Felder
- Department of General Physiology, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
| | - Patrick Paul
- Institute for Experimental Physics, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
| | - Kay-Eberhard Gottschalk
- Institute for Experimental Physics, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
| | - Manfred Frick
- Department of General Physiology, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
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Neuland K, Sharma N, Frick M. Synaptotagmin-7 links fusion-activated Ca²⁺ entry and fusion pore dilation. J Cell Sci 2014; 127:5218-27. [PMID: 25344253 PMCID: PMC4265738 DOI: 10.1242/jcs.153742] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Ca(2+)-dependent regulation of fusion pore dilation and closure is a key mechanism determining the output of cellular secretion. We have recently described 'fusion-activated' Ca(2+) entry (FACE) following exocytosis of lamellar bodies in alveolar type II cells. FACE regulates fusion pore expansion and facilitates secretion. However, the mechanisms linking this locally restricted Ca(2+) signal and fusion pore expansion were still elusive. Here, we demonstrate that synaptotagmin-7 (Syt7) is expressed on lamellar bodies and links FACE and fusion pore dilation. We directly assessed dynamic changes in fusion pore diameters by analysing diffusion of fluorophores across fusion pores. Expressing wild-type Syt7 or a mutant Syt7 with impaired Ca(2+)-binding to the C2 domains revealed that binding of Ca(2+) to the C2A domain facilitates FACE-induced pore dilation, probably by inhibiting translocation of complexin-2 to fused vesicles. However, the C2A domain hampered Ca(2+)-dependent exocytosis of lamellar bodies. These findings support the hypothesis that Syt7 modulates fusion pore expansion in large secretory organelles and extend our picture that lamellar bodies contain the necessary molecular inventory to facilitate secretion during the exocytic post-fusion phase. Moreover, regulating Syt7 levels on lamellar bodies appears to be essential in order that exocytosis is not impeded during the pre-fusion phase.
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Affiliation(s)
- Kathrin Neuland
- Institute of General Physiology, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
| | - Neeti Sharma
- Institute of General Physiology, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
| | - Manfred Frick
- Institute of General Physiology, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
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48
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Masedunskas A, Appaduray M, Hardeman EC, Gunning PW. What makes a model system great? INTRAVITAL 2014. [DOI: 10.4161/intv.26287] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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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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Mahto SK, Tenenbaum-Katan J, Greenblum A, Rothen-Rutishauser B, Sznitman J. Microfluidic shear stress-regulated surfactant secretion in alveolar epithelial type II cells in vitro. Am J Physiol Lung Cell Mol Physiol 2014; 306:L672-83. [PMID: 24487389 DOI: 10.1152/ajplung.00106.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the role of flow-induced shear stress on the mechanisms regulating surfactant secretion in type II alveolar epithelial cells (ATII) using microfluidic models. Following flow stimulation spanning a range of wall shear stress (WSS) magnitudes, monolayers of ATII (MLE-12 and A549) cells were examined for surfactant secretion by evaluating essential steps of the process, including relative changes in the number of fusion events of lamellar bodies (LBs) with the plasma membrane (PM) and intracellular redistribution of LBs. F-actin cytoskeleton and calcium levels were analyzed in A549 cells subjected to WSS spanning 4-20 dyn/cm(2). Results reveal an enhancement in LB fusion events with the PM in MLE-12 cells upon flow stimulation, whereas A549 cells exhibit no foreseeable changes in the monitored number of fusion events for WSS levels ranging up to a threshold of ∼8 dyn/cm(2); above this threshold, we witness instead a decrease in LB fusion events in A549 cells. However, patterns of LB redistribution suggest that WSS can potentially serve as a stimulus for A549 cells to trigger the intracellular transport of LBs toward the cell periphery. This observation is accompanied by a fragmentation of F-actin, indicating that disorganization of the F-actin cytoskeleton might act as a limiting factor for LB fusion events. Moreover, we note a rise in cytosolic calcium ([Ca(2+)]c) levels following stimulation of A549 cells with WSS magnitudes ranging near or above the experimental threshold. Overall, WSS stimulation can influence key components of molecular machinery for regulated surfactant secretion in ATII cells in vitro.
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