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Liu X, Xu J, Zhang M, Wang H, Guo X, Zhao M, Duan M, Guan Z, Guo Y. RABV induces biphasic actin cytoskeletal rearrangement through Rac1 activity modulation. J Virol 2024; 98:e0060624. [PMID: 38809020 PMCID: PMC11264595 DOI: 10.1128/jvi.00606-24] [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: 04/06/2024] [Accepted: 05/03/2024] [Indexed: 05/30/2024] Open
Abstract
Rabies virus (RABV) is highly lethal and triggers severe neurological symptoms. The neuropathogenic mechanism remains poorly understood. Ras-related C3 botulinum toxin substrate 1 (Rac1) is a Rho-GTPase that is involved in actin remodeling and has been reported to be closely associated with neuronal dysfunction. In this study, by means of a combination of pharmacological inhibitors, small interfering RNA, and specific dominant-negatives, we characterize the crucial roles of dynamic actin and the regulatory function of Rac1 in RABV infection, dominantly in the viral entry phase. The data show that the RABV phosphoprotein interacts with Rac1. RABV phosphoprotein suppress Rac1 activity and impedes downstream Pak1-Limk1-Cofilin1 signaling, leading to the disruption of F-actin-based structure formation. In early viral infection, the EGFR-Rac1-signaling pathway undergoes a biphasic change, which is first upregulated and subsequently downregulated, corresponding to the RABV entry-induced remodeling pattern of F-actin. Taken together, our findings demonstrate for the first time the role played by the Rac1 signaling pathway in RABV infection and may provide a clue for an explanation for the etiology of rabies neurological pathogenesis.IMPORTANCEThough neuronal dysfunction is predominant in fatal rabies, the detailed mechanism by which rabies virus (RABV) infection causes neurological symptoms remains in question. The actin cytoskeleton is involved in numerous viruses infection and plays a crucial role in maintaining neurological function. The cytoskeletal disruption is closely associated with abnormal nervous symptoms and induces neurogenic diseases. In this study, we show that RABV infection led to the rearrangement of the cytoskeleton as well as the biphasic kinetics of the Rac1 signal transduction. These results help elucidate the mechanism that causes the aberrant neuronal processes by RABV infection and may shed light on therapeutic development aimed at ameliorating neurological disorders.
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Affiliation(s)
- Xiaomin Liu
- Institute of Zoonosis, College of Veterinary Medicine, Jilin University, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Changchun, China
| | - Jing Xu
- Institute of Zoonosis, College of Veterinary Medicine, Jilin University, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Changchun, China
| | - Maolin Zhang
- Institute of Zoonosis, College of Veterinary Medicine, Jilin University, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Changchun, China
| | - Hualei Wang
- Institute of Zoonosis, College of Veterinary Medicine, Jilin University, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Changchun, China
| | - Xin Guo
- Institute of Zoonosis, College of Veterinary Medicine, Jilin University, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Changchun, China
| | - Mingxin Zhao
- Institute of Zoonosis, College of Veterinary Medicine, Jilin University, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Changchun, China
| | - Ming Duan
- Institute of Zoonosis, College of Veterinary Medicine, Jilin University, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Changchun, China
| | - Zhenhong Guan
- Institute of Zoonosis, College of Veterinary Medicine, Jilin University, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Changchun, China
| | - Yidi Guo
- Institute of Zoonosis, College of Veterinary Medicine, Jilin University, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Changchun, China
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Caillaud MC. Tools for studying the cytoskeleton during plant cell division. TRENDS IN PLANT SCIENCE 2022; 27:1049-1062. [PMID: 35667969 DOI: 10.1016/j.tplants.2022.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 04/28/2022] [Accepted: 05/11/2022] [Indexed: 06/15/2023]
Abstract
The plant cytoskeleton regulates fundamental biological processes, including cell division. How to experimentally perturb the cytoskeleton is a key question if one wants to understand the role of both actin filaments (AFs) and microtubules (MTs) in a given biological process. While a myriad of mutants are available, knock-out in cytoskeleton regulators, when nonlethal, often produce little or no phenotypic perturbation because such regulators are often part of a large family, leading to functional redundancy. In this review, alternative techniques to modify the plant cytoskeleton during plant cell division are outlined. The different pharmacological and genetic approaches already developed in cell culture, transient assays, or in whole organisms are presented. Perspectives on the use of optogenetics to perturb the plant cytoskeleton are also discussed.
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Affiliation(s)
- Marie-Cécile Caillaud
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, F-69342 Lyon, France.
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Lu HJ, Nguyen TL, Hong GS, Pak S, Kim H, Kim H, Kim DY, Kim SY, Shen Y, Ryu PD, Lee MO, Oh U. Tentonin 3/TMEM150C senses blood pressure changes in the aortic arch. J Clin Invest 2021; 130:3671-3683. [PMID: 32484458 DOI: 10.1172/jci133798] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 03/24/2020] [Indexed: 01/09/2023] Open
Abstract
The baroreceptor reflex is a powerful neural feedback that regulates arterial pressure (AP). Mechanosensitive channels transduce pulsatile AP to electrical signals in baroreceptors. Here we show that tentonin 3 (TTN3/TMEM150C), a cation channel activated by mechanical strokes, is essential for detecting AP changes in the aortic arch. TTN3 was expressed in nerve terminals in the aortic arch and nodose ganglion (NG) neurons. Genetic ablation of Ttn3 induced ambient hypertension, tachycardia, AP fluctuations, and impaired baroreflex sensitivity. Chemogenetic silencing or activation of Ttn3+ neurons in the NG resulted in an increase in AP and heart rate, or vice versa. More important, overexpression of Ttn3 in the NG of Ttn3-/- mice reversed the cardiovascular changes observed in Ttn3-/- mice. We conclude that TTN3 is a molecular component contributing to the sensing of dynamic AP changes in baroreceptors.
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Affiliation(s)
- Huan-Jun Lu
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea.,College of Pharmacy
| | - Thien-Luan Nguyen
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea.,College of Pharmacy
| | - Gyu-Sang Hong
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea
| | - Sungmin Pak
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea
| | - Hyesu Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea
| | - Hyungsup Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea
| | | | - Sung-Yon Kim
- Institute of Molecular Biology and Genetics, and
| | - Yiming Shen
- College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | - Pan Dong Ryu
- College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | | | - Uhtaek Oh
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea
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CCN1-Yes-Associated Protein Feedback Loop Regulates Physiological and Pathological Angiogenesis. Mol Cell Biol 2019; 39:MCB.00107-19. [PMID: 31262999 DOI: 10.1128/mcb.00107-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 06/23/2019] [Indexed: 01/08/2023] Open
Abstract
Cellular communication network factor 1 (CCN1) is a dynamically expressed, matricellular protein required for vascular development and tissue repair. The CCN1 gene is a presumed target of Yes-associated protein (YAP), a transcriptional coactivator that regulates cell growth and organ size. Herein, we demonstrate that the CCN1 promoter is indeed a direct genomic target of YAP in endothelial cells (ECs) of new blood vessel sprouts and that YAP deficiency in mice downregulates CCN1 and alters cytoskeletal and mitogenic gene expression. Interestingly, CCN1 overexpression in cultured ECs inactivates YAP in a negative feedback and causes its nuclear exclusion. Accordingly, EC-specific deletion of the CCN1 gene in mice mimics a YAP gain-of-function phenotype, characterized by EC hyperproliferation and blood vessel enlargement. CCN1 brings about its effect by providing cells with a soft compliant matrix that creates YAP-repressive cytoskeletal states. Concordantly, pharmacological inhibition of cell stiffness recapitulates the CCN1 deletion vascular phenotype. Furthermore, adeno-associated virus-mediated expression of CCN1 reversed the pathology of YAP hyperactivation and the subsequent aberrant growth of blood vessels in mice with ischemic retinopathy. Our studies unravel a new paradigm of functional interaction between CCN1 and YAP and underscore the significance of their interplay in the pathogenesis of neovascular diseases.
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Brückner BR, Nöding H, Skamrahl M, Janshoff A. Mechanical and morphological response of confluent epithelial cell layers to reinforcement and dissolution of the F-actin cytoskeleton. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 144:77-90. [DOI: 10.1016/j.pbiomolbio.2018.08.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 07/09/2018] [Accepted: 08/26/2018] [Indexed: 12/22/2022]
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Zhang HM, Colyvas K, Patrick JW, Offler CE. A Ca2+-dependent remodelled actin network directs vesicle trafficking to build wall ingrowth papillae in transfer cells. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:4749-4764. [PMID: 29048561 PMCID: PMC5853249 DOI: 10.1093/jxb/erx315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Accepted: 08/02/2017] [Indexed: 05/18/2023]
Abstract
The transport function of transfer cells is conferred by an enlarged plasma membrane area, enriched in nutrient transporters, that is supported on a scaffold of wall ingrowth (WI) papillae. Polarized plumes of elevated cytosolic Ca2+ define loci at which WI papillae form in developing adaxial epidermal transfer cells of Vicia faba cotyledons that are induced to trans-differentiate when the cotyledons are placed on culture medium. We evaluated the hypothesis that vesicle trafficking along a Ca2+-regulated remodelled actin network is the mechanism that underpins this outcome. Polarized to the outer periclinal cytoplasm, a Ca2+-dependent remodelling of long actin bundles into short, thin bundles was found to be essential for assembling WI papillae but not the underlying uniform wall layer. The remodelled actin network directed polarized vesicle trafficking to sites of WI papillae construction, and a pharmacological study indicated that both exo- and endocytosis contributed to assembly of the papillae. Potential candidates responsible for the Ca2+-dependent actin remodelling, along with those underpinning polarized exo- and endocyotosis, were identified in a transcriptome RNAseq database generated from the trans-differentiating epidermal cells. Of most significance, endocytosis was controlled by up-regulated expression of a dynamin-like isoform. How a cycle of localized exo- and endocytosis, regulated by Ca2+-dependent actin remodelling, assembles WI papillae is discussed.
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Affiliation(s)
| | - Kim Colyvas
- School of Mathematical and Physical Sciences, The University of Newcastle, Newcastle NSW, Australia
| | - John W Patrick
- School of Environmental and Life Sciences
- Correspondence: or
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Celler K, Fujita M, Kawamura E, Ambrose C, Herburger K, Holzinger A, Wasteneys GO. Microtubules in Plant Cells: Strategies and Methods for Immunofluorescence, Transmission Electron Microscopy, and Live Cell Imaging. Methods Mol Biol 2016; 1365:155-84. [PMID: 26498784 DOI: 10.1007/978-1-4939-3124-8_8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Microtubules (MTs) are required throughout plant development for a wide variety of processes, and different strategies have evolved to visualize and analyze them. This chapter provides specific methods that can be used to analyze microtubule organization and dynamic properties in plant systems and summarizes the advantages and limitations for each technique. We outline basic methods for preparing samples for immunofluorescence labeling, including an enzyme-based permeabilization method, and a freeze-shattering method, which generates microfractures in the cell wall to provide antibodies access to cells in cuticle-laden aerial organs such as leaves. We discuss current options for live cell imaging of MTs with fluorescently tagged proteins (FPs), and provide chemical fixation, high-pressure freezing/freeze substitution, and post-fixation staining protocols for preserving MTs for transmission electron microscopy and tomography.
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Affiliation(s)
- Katherine Celler
- Department of Botany, The University of British Columbia, Vancouver, BC, Canada
| | - Miki Fujita
- Department of Botany, The University of British Columbia, Vancouver, BC, Canada
| | - Eiko Kawamura
- Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Chris Ambrose
- Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Klaus Herburger
- Functional Plant Biology, Institute of Botany, University of Innsbruck, Sternwartestraße 15, 6020, Innsbruck, Austria
| | - Andreas Holzinger
- Functional Plant Biology, Institute of Botany, University of Innsbruck, Sternwartestraße 15, 6020, Innsbruck, Austria.
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Actin-Dynamics in Plant Cells: The Function of Actin-Perturbing Substances: Jasplakinolide, Chondramides, Phalloidin, Cytochalasins, and Latrunculins. Methods Mol Biol 2016; 1365:243-61. [PMID: 26498789 DOI: 10.1007/978-1-4939-3124-8_13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This chapter gives an overview of the most common F-actin-perturbing substances that are used to study actin dynamics in living plant cells in studies on morphogenesis, motility, organelle movement, or when apoptosis has to be induced. These substances can be divided into two major subclasses: F-actin-stabilizing and -polymerizing substances like jasplakinolide and chondramides and F-actin-severing compounds like chytochalasins and latrunculins. Jasplakinolide was originally isolated form a marine sponge, and can now be synthesized and has become commercially available, which is responsible for its wide distribution as membrane-permeable F-actin-stabilizing and -polymerizing agent, which may even have anticancer activities. Cytochalasins, derived from fungi, show an F-actin-severing function and many derivatives are commercially available (A, B, C, D, E, H, J), also making it a widely used compound for F-actin disruption. The same can be stated for latrunculins (A, B), derived from red sea sponges; however the mode of action is different by binding to G-actin and inhibiting incorporation into the filament. In the case of swinholide a stable complex with actin dimers is formed resulting also in severing of F-actin. For influencing F-actin dynamics in plant cells only membrane permeable drugs are useful in a broad range. We however introduce also the phallotoxins and synthetic derivatives, as they are widely used to visualize F-actin in fixed cells. A particular uptake mechanism has been shown for hepatocytes, but has also been described in siphonal giant algae. In the present chapter the focus is set on F-actin dynamics in plant cells where alterations in cytoplasmic streaming can be particularly well studied; however methods by fluorescence applications including phalloidin and antibody staining as well as immunofluorescence-localization of the inhibitor drugs are given.
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Chang M, Huang S. Arabidopsis ACT11 modifies actin turnover to promote pollen germination and maintain the normal rate of tube growth. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 83:515-527. [PMID: 26096143 DOI: 10.1111/tpj.12910] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 05/21/2015] [Accepted: 06/01/2015] [Indexed: 06/04/2023]
Abstract
Actin is an ancient conserved protein that is encoded by multiple isovariants in multicellular organisms. There are eight functional actin genes in the Arabidopsis genome, and the precise function and mechanism of action of each isovariant remain poorly understood. Here, we report the characterization of ACT11, a reproductive actin isovariant. Our studies reveal that loss of function of ACT11 causes a delay in pollen germination, but enhances pollen tube growth. Cytological analysis revealed that the amount of filamentous actin decreased, and the rate of actin turnover increased in act11 pollen. Convergence of actin filaments upon the germination aperture was impaired in act11 pollen, consistent with the observed delay of germination. Reduction of actin dynamics with jasplakinolide suppressed the germination and tube growth phenotypes in act11 pollen, suggesting that the underlying mechanisms involve an increase in actin dynamics. Thus, we demonstrate that ACT11 is required to maintain the rate of actin turnover in order to promote pollen germination and maintain the normal rate of pollen tube growth.
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Affiliation(s)
- Ming Chang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shanjin Huang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- National Center for Plant Gene Research, Beijing, 100101, China
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Zhou GZ, Cao FK, Du SW. The apoptotic pathways in the curcumin analog MHMD-induced lung cancer cell death and the essential role of actin polymerization during apoptosis. Biomed Pharmacother 2015; 71:128-34. [DOI: 10.1016/j.biopha.2015.02.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 02/21/2015] [Indexed: 01/13/2023] Open
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11
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Trendowski M. Exploiting the cytoskeletal filaments of neoplastic cells to potentiate a novel therapeutic approach. Biochim Biophys Acta Rev Cancer 2014; 1846:599-616. [PMID: 25286320 DOI: 10.1016/j.bbcan.2014.09.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 09/19/2014] [Accepted: 09/21/2014] [Indexed: 02/06/2023]
Abstract
Although cytoskeletal-directed agents have been a mainstay in chemotherapeutic protocols due to their ability to readily interfere with the rapid mitotic progression of neoplastic cells, they are all microtubule-based drugs, and there has yet to be any microfilament- or intermediate filament-directed agents approved for clinical use. There are many inherent differences between the cytoskeletal networks of malignant and normal cells, providing an ideal target to attain preferential damage. Further, numerous microfilament-directed agents, and an intermediate filament-directed agent of particular interest (withaferin A) have demonstrated in vitro and in vivo efficacy, suggesting that cytoskeletal filaments may be exploited to supplement chemotherapeutic approaches currently used in the clinical setting. Therefore, this review is intended to expose academics and clinicians to the tremendous variety of cytoskeletal filament-directed agents that are currently available for further chemotherapeutic evaluation. The mechanisms by which microfilament directed- and intermediate filament-directed agents damage malignant cells are discussed in detail in order to establish how the drugs can be used in combination with each other, or with currently approved chemotherapeutic agents to generate a substantial synergistic attack, potentially establishing a new paradigm of chemotherapeutic agents.
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Affiliation(s)
- Matthew Trendowski
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY 13244, USA.
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Natarajan P, Crothers JM, Rosen JE, Nakada SL, Rakholia M, Okamoto CT, Forte JG, Machen TE. Myosin IIB and F-actin control apical vacuolar morphology and histamine-induced trafficking of H-K-ATPase-containing tubulovesicles in gastric parietal cells. Am J Physiol Gastrointest Liver Physiol 2014; 306:G699-710. [PMID: 24578340 PMCID: PMC3989701 DOI: 10.1152/ajpgi.00316.2013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Selective inhibitors of myosin or actin function and confocal microscopy were used to test the role of an actomyosin complex in controlling morphology, trafficking, and fusion of tubulovesicles (TV) containing H-K-ATPase with the apical secretory canaliculus (ASC) of primary-cultured rabbit gastric parietal cells. In resting cells, myosin IIB and IIC, ezrin, and F-actin were associated with ASC, whereas H-K-ATPase localized to intracellular TV. Histamine caused fusion of TV with ASC and subsequent expansion resulting from HCl and water secretion; F-actin and ezrin remained associated with ASC whereas myosin IIB and IIC appeared to dissociate from ASC and relocalize to the cytoplasm. ML-7 (inhibits myosin light chain kinase) caused ASC of resting cells to collapse and most myosin IIB, F-actin, and ezrin to dissociate from ASC. TV were unaffected by ML-7. Jasplakinolide (stabilizes F-actin) caused ASC to develop large blebs to which actin, myosin II, and ezrin, as well as tubulin, were prominently localized. When added prior to stimulation, ML-7 and jasplakinolide prevented normal histamine-stimulated transformations of ASC/TV and the cytoskeleton, but they did not affect cells that had been previously stimulated with histamine. These results indicate that dynamic pools of actomyosin are required for maintenance of ASC structure in resting cells and for trafficking of TV to ASC during histamine stimulation. However, the dynamic pools of actomyosin are not required once the histamine-stimulated transformation of TV/ASC and cytoskeleton has occurred. These results also show that vesicle trafficking in parietal cells shares mechanisms with similar processes in renal collecting duct cells, neuronal synapses, and skeletal muscle.
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Affiliation(s)
- Paramasivam Natarajan
- 1Department of Molecular and Cell Biology, University of California, Berkeley, California; and
| | - James M. Crothers
- 1Department of Molecular and Cell Biology, University of California, Berkeley, California; and
| | - Jared E. Rosen
- 1Department of Molecular and Cell Biology, University of California, Berkeley, California; and
| | - Stephanie L. Nakada
- 1Department of Molecular and Cell Biology, University of California, Berkeley, California; and
| | - Milap Rakholia
- 1Department of Molecular and Cell Biology, University of California, Berkeley, California; and
| | - Curtis T. Okamoto
- 2Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California
| | - John G. Forte
- 1Department of Molecular and Cell Biology, University of California, Berkeley, California; and
| | - Terry E. Machen
- 1Department of Molecular and Cell Biology, University of California, Berkeley, California; and
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A new antiproliferative and antioxidant peptide isolated from Arca subcrenata. Mar Drugs 2013; 11:1800-14. [PMID: 23708186 PMCID: PMC3721206 DOI: 10.3390/md11061800] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 04/22/2013] [Accepted: 05/08/2013] [Indexed: 01/31/2023] Open
Abstract
A new antitumor and antioxidant peptide (H3) was isolated from Arca subcrenata Lischke using ion exchange and hydrophobic column chromatography. The purity of H3 was over 99.3% in reversed phase-high performance liquid chromatography (RP-HPLC) and the molecular weight was determined to be 20,491.0 Da by electrospray-ionization mass spectrometry (ESI-MS/MS). The isoelectric point of H3 was measured to be 6.65 by isoelectric focusing-polyacrylamide gel electrophoresis. Partial amino acid sequence of this peptide was determined as ISMEDVEESRKNGMHSIDVNHDGKHRAYWADNTYLM-KCMDLPYDVLDTGGKDRSSDKNTDLVDLFELDMVPDRKNNECMNMIMDVIDTN-TAARPYYCSLDVNHDGAGLSMEDVEEDK via MALDI-TOF/TOF-MS and de novo sequencing. The in vitro antitumor activity of H3 was evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The result indicated that H3 exhibited significant antiproliferative activity against HeLa, HepG2 and HT-29 cell lines with IC50 values of 10.8, 10.1 and 10.5 μg/mL. The scavenging percentage of H3 at 8 mg/mL to 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals were 56.8% and 47.5%, respectively.
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African swine fever virus uses macropinocytosis to enter host cells. PLoS Pathog 2012; 8:e1002754. [PMID: 22719252 PMCID: PMC3375293 DOI: 10.1371/journal.ppat.1002754] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 04/30/2012] [Indexed: 12/16/2022] Open
Abstract
African swine fever (ASF) is caused by a large and highly pathogenic DNA virus, African swine fever virus (ASFV), which provokes severe economic losses and expansion threats. Presently, no specific protection or vaccine against ASF is available, despite the high hazard that the continued occurrence of the disease in sub-Saharan Africa, the recent outbreak in the Caucasus in 2007, and the potential dissemination to neighboring countries, represents. Although virus entry is a remarkable target for the development of protection tools, knowledge of the ASFV entry mechanism is still very limited. Whereas early studies have proposed that the virus enters cells through receptor-mediated endocytosis, the specific mechanism used by ASFV remains uncertain. Here we used the ASFV virulent isolate Ba71, adapted to grow in Vero cells (Ba71V), and the virulent strain E70 to demonstrate that entry and internalization of ASFV includes most of the features of macropinocytosis. By a combination of optical and electron microscopy, we show that the virus causes cytoplasm membrane perturbation, blebbing and ruffles. We have also found that internalization of the virions depends on actin reorganization, activity of Na+/H+ exchangers, and signaling events typical of the macropinocytic mechanism of endocytosis. The entry of virus into cells appears to directly stimulate dextran uptake, actin polarization and EGFR, PI3K-Akt, Pak1 and Rac1 activation. Inhibition of these key regulators of macropinocytosis, as well as treatment with the drug EIPA, results in a considerable decrease in ASFV entry and infection. In conclusion, this study identifies for the first time the whole pathway for ASFV entry, including the key cellular factors required for the uptake of the virus and the cell signaling involved. ASFV is a highly pathogenic zoonotic virus, which can cause severe economic losses and bioterrorism threats. No vaccine against ASFV is available so far. A strong hazard of ASFV dissemination through EU countries from Caucasian areas has recently emerged, thus making urgent to acquire knowledge and tools for protection against this virus. Despite that, our understanding of how ASFV enters host cells is very limited. A thorough understanding of this process would enable to design targeted antiviral therapies and vaccine development. The present study clearly defines key steps of ASFV cellular uptake, as well as the host factors responsible for permitting virus entry into cells. Our results indicate that the primary mechanism of ASFV uptake is a macropinocytosis-like process, that involves cellular membrane perturbation, actin polarization, activity of Na+/H+ membrane channels, and signaling proceedings typical of the macropinocytic mechanism of endocytosis, such as Rac1-Pak1 pathways, PI3K and tyrosine-kinases activation. These findings help understanding how ASFV infects cells and suggest that disturbance of macropinocytosis may be useful in the impairment of infection and vaccine development.
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Vannerum K, De Rycke R, Pollier J, Goossens A, Inzé D, Vyverman AW. CHARACTERIZATION OF A RABE (RAS GENE FROM RAT BRAIN E) GTPASE EXPRESSED DURING MORPHOGENESIS IN THE UNICELLULAR GREEN ALGA MICRASTERIAS DENTICULATA (ZYGNEMATOPHYCEAE, STREPTOPHYTA)(1). JOURNAL OF PHYCOLOGY 2012; 48:682-692. [PMID: 27011085 DOI: 10.1111/j.1529-8817.2012.01170.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Rab GTPases are central regulators of cell shape in land plants by coordinating vesicle trafficking during morphogenesis. To date, relatively little is known about the role of these ubiquitous signaling proteins during cell growth in microalgae, in particular in the related charophyte algae. This article identifies the first charophyte Rab GTPase, MdRABE1, in Micrasterias denticulata Bréb., a convenient model organism for studying morphogenesis. Its expression correlated with the onset of morphogenesis, and structural analysis indicated that it belongs to the RABE (Ras gene from rat brain E) subclass. Confocal fluorescence and immunoelectron microscopy (IEM) of transiently GFP-MdRABE1 overexpressing interphase cells demonstrated that the GFP-MdRABE1 protein was localized to the endoplasmic reticulum, dictyosomes, exocytotic vesicles, the cell margin, the membranes of cell organelles, and in the isthmus zone around the nucleus. Although overexpression phenotyping of both N- and C-terminal green fluorescent protein (GFP) fusions failed to indicate additional functional evidence of the MdRABE1 protein due to mortality of those transgenic cells, its expression profile, bioinformatics, and intracellular localization suggest a role in vesicle trafficking during morphogenesis.
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Affiliation(s)
- Katrijn Vannerum
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Gent, BelgiumDepartment of Plant Systems Biology, VIB, Technologiepark 927, 9052 Gent, BelgiumDepartment of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052 Gent, Belgium
| | - Riet De Rycke
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Gent, BelgiumDepartment of Plant Systems Biology, VIB, Technologiepark 927, 9052 Gent, BelgiumDepartment of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052 Gent, Belgium
| | - Jacob Pollier
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Gent, BelgiumDepartment of Plant Systems Biology, VIB, Technologiepark 927, 9052 Gent, BelgiumDepartment of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052 Gent, Belgium
| | - Alain Goossens
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Gent, BelgiumDepartment of Plant Systems Biology, VIB, Technologiepark 927, 9052 Gent, BelgiumDepartment of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052 Gent, Belgium
| | - Dirk Inzé
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Gent, BelgiumDepartment of Plant Systems Biology, VIB, Technologiepark 927, 9052 Gent, BelgiumDepartment of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052 Gent, Belgium
| | - And Wim Vyverman
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Gent, BelgiumDepartment of Plant Systems Biology, VIB, Technologiepark 927, 9052 Gent, BelgiumDepartment of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052 Gent, Belgium
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Bioactive peptides and depsipeptides with anticancer potential: sources from marine animals. Mar Drugs 2012; 10:963-986. [PMID: 22822350 PMCID: PMC3397454 DOI: 10.3390/md10050963] [Citation(s) in RCA: 161] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Revised: 03/24/2012] [Accepted: 04/05/2012] [Indexed: 11/30/2022] Open
Abstract
Biologically active compounds with different modes of action, such as, antiproliferative, antioxidant, antimicrotubule, have been isolated from marine sources, specifically algae and cyanobacteria. Recently research has been focused on peptides from marine animal sources, since they have been found as secondary metabolites from sponges, ascidians, tunicates, and mollusks. The structural characteristics of these peptides include various unusual amino acid residues which may be responsible for their bioactivity. Moreover, protein hydrolysates formed by the enzymatic digestion of aquatic and marine by-products are an important source of bioactive peptides. Purified peptides from these sources have been shown to have antioxidant activity and cytotoxic effect on several human cancer cell lines such as HeLa, AGS, and DLD-1. These characteristics imply that the use of peptides from marine sources has potential for the prevention and treatment of cancer, and that they might also be useful as molecular models in anticancer drug research. This review focuses on the latest studies and critical research in this field, and evidences the immense potential of marine animals as bioactive peptide sources.
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Sharma N, Kosan ZA, Stallworth JE, Berbari NF, Yoder BK. Soluble levels of cytosolic tubulin regulate ciliary length control. Mol Biol Cell 2011; 22:806-16. [PMID: 21270438 PMCID: PMC3057705 DOI: 10.1091/mbc.e10-03-0269] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
We show that manipulation of either the microtubule or the actin cytoskeleton has unexpected influences on cilia length control. The primary cilium is an evolutionarily conserved dynamic organelle important for regulating numerous signaling pathways, and, as such, mutations disrupting ciliogenesis result in a variety of developmental abnormalities and postnatal disorders. The length of the cilium is regulated by the cell through largely unknown mechanisms. Normal cilia length is important, as either shortened or elongated cilia have been associated with disease and developmental defects. Here we explore the importance of cytoskeletal dynamics in regulating cilia length. Using pharmacological approaches in different cell types, we demonstrate that actin depolymerization or stabilization and protein kinase A activation result in a rapid elongation of the primary cilium. The effects of pharmacological agents on cilia length are associated with a subsequent increase in soluble tubulin levels and can be impaired by depletion of soluble tubulin with taxol. In addition, subtle nocodazole treatment was able to induce ciliogenesis under conditions in which cilia are not normally formed and also increases cilia length on cells that have already established cilia. Together these data indicate that cilia length can be regulated through changes in either the actin or microtubule network and implicate a possible role for soluble tubulin levels in cilia length control.
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Affiliation(s)
- Neeraj Sharma
- Department of Cell Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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18
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Rott E, Holzinger A, Gesierich D, Kofler W, Sanders D. Cell morphology, ultrastructure, and calcification pattern of Oocardium stratum, a peculiar lotic desmid. PROTOPLASMA 2010; 243:39-50. [PMID: 19455279 DOI: 10.1007/s00709-009-0050-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Accepted: 05/04/2009] [Indexed: 05/27/2023]
Abstract
Cell morphology and ultrastructure of the desmid Oocardium stratum and its habitat conditions in two limestone-precipitating spring habitats in the Alps were studied. In spite of specific cell geometry, we found ultrastructural features (nucleus with nucleolus, Golgi apparatus, chloroplast structure, lipid bodies, cell wall texture) closely related to other desmids. The type of the mucilage pore apparatus perforating in high densities extended areas of the cell wall of Oocardium is of the Cosmarium type. Oocardium contrasts to Cosmarium by a peculiar bilateral cell geometry (lateral sphenoid shape) which is combined with a dislocated nucleus. Although the cell features of Oocardium did not differ between the two habitats, different calcification types (rhombohedral calcite versus fascicular-fibrous calcite) and calcification intensities were recorded. The spatial positioning and extension of the Oocardium niches differed considerably between the two springs in spite of high CO(2) oversaturation at both sites.
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Affiliation(s)
- E Rott
- Faculty of Biology, Arbeitsgruppe Hydrobotanik, Institute of Botany, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria.
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Gil-Krzewska AJ, Farber E, Buttner EA, Hunter CP. Regulators of the actin cytoskeleton mediate lethality in a Caenorhabditis elegans dhc-1 mutant. Mol Biol Cell 2010; 21:2707-20. [PMID: 20554764 PMCID: PMC2912356 DOI: 10.1091/mbc.e09-07-0593] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Both LIS-1 and the dynein heavy-chain DHC-1 are required for integrity of the actin cytoskeleton in Caenorhabditis elegans. An RNAi screen revealed that knockdown of other actin regulators, including actin-capping protein genes and prefoldin subunit genes, suppresses dhc-1(or195ts)–induced lethality. Functional analysis of cytoplasmic dynein in Caenorhabditis elegans has revealed a wide range of cellular functions for this minus-end–directed motor protein. Dynein transports a variety of cargos to diverse cellular locations, and thus cargo selection and destination are likely regulated by accessory proteins. The microtubule-associated proteins LIS-1 and dynein interact, but the nature of this interaction remains poorly understood. Here we show that both LIS-1 and the dynein heavy-chain DHC-1 are required for integrity of the actin cytoskeleton in C. elegans. Although both dhc-1(or195ts) and lis-1 loss-of-function disrupt the actin cytoskeleton and produce embryonic lethality, a double mutant suppresses these defects. A targeted RNA interference screen revealed that knockdown of other actin regulators, including actin-capping protein genes and prefoldin subunit genes, suppresses dhc-1(or195ts)–induced lethality. We propose that release or relocation of the mutant dynein complex mediates this suppression of dhc-1(or195ts)--induced phenotypes. These results reveal an unexpected direct or indirect interaction between the actin cytoskeleton and dynein activity.
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Abstract
Microtubules are required throughout plant development for a wide variety of processes, and different strategies have been evolved to visualize them. This chapter summarizes the most effective of these methods and points out potential problems and pitfalls. We outline the freeze-shattering method for immunolabeling microtubules in aerial organs such as leaves that require mechanical permeabilization, discuss current options for live cell imaging of MTs with fluorescently tagged proteins (FPs), and provide different fixation protocols for preserving MTs for transmission electron microscopy including chemical fixation, high pressure freezing/freeze substitution, and post-fixation staining procedures for transmission electron microscopy.
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Affiliation(s)
- Andreas Holzinger
- Institute of Botany, Department of Physiology and Cell Physiology, University of Innsbruck, Innsbruck, Austria
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21
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Holzinger A. Jasplakinolide: an actin-specific reagent that promotes actin polymerization. Methods Mol Biol 2010; 586:71-87. [PMID: 19768425 DOI: 10.1007/978-1-60761-376-3_4] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Jasplakinolide, a cyclo-depsipeptide is a commonly used actin filament polymerizing and stabilizing drug. The substance has originally been isolated from a marine sponge, and can now be synthesized and has become commercially available. This, together with the benefit that jasplakinolide is membrane permeable has made it a commonly used tool in cell biology, when actin filament stabilization or polymerization has to be achieved. This may either be the case in studies on morphogenesis, motility, organelle movement, or when apoptosis has to be induced. Its use as a potent anticancer drug is discussed. The direct action on actin filaments may have further consequences in golgi body and membrane raft protein organization. In this chapter, the visualization of jasplaklinolide effects by different fluorescent and transmission electron microscopic methods is described. As competitive binding capacities of jasplakinolide and phalloidin make the detection of actin filaments by fluorescently labeled phalloidin problematic, alternatives are given here.
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Affiliation(s)
- Andreas Holzinger
- Institute of Botany, Department of Physiology and Cell Physiology, University of Innsbruck, Innsbruck, Austria
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22
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Andavan GSB, Lemmens-Gruber R. Cyclodepsipeptides from marine sponges: natural agents for drug research. Mar Drugs 2010; 8:810-34. [PMID: 20411126 PMCID: PMC2857363 DOI: 10.3390/md8030810] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 03/04/2010] [Accepted: 03/19/2010] [Indexed: 11/24/2022] Open
Abstract
A number of natural products from marine sponges, such as cyclodepsipeptides, have been identified. The structural characteristics of this family of cyclic peptides include various unusual amino acid residues and unique N-terminal polyketide-derived moieties. Papuamides are representatives of a class of marine sponge derived cyclic depsipeptides, including callipeltin A, celebesides A and B, homophymine A, mirabamides, microspinosamide, neamphamide A and theopapuamides. They are thought to have cytoprotective activity against HIV-1 in vitro by inhibiting viral entry. Jasplakinolide, a representative member of marine sponge-derived cyclodepsipeptides that include arenastatin A, geodiamolides, homophymines, spongidepsin and theopapuamides, is a potent inducer of actin polymerization in vitro. Although actin dynamics is essential for tumor metasasis, no actin targeting drugs have been used in clinical trials due to their severe cytotoxicity. Nonetheless, the actin cytoskeleton remains a potential target for anti-cancer drug development. These features imply the use of cyclodepsipeptides as molecular models in drug research.
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Affiliation(s)
| | - Rosa Lemmens-Gruber
- * Author to whom correspondence should be addressed; E-Mail:
; Tel.: +43-1-4277-55325; Fax: +43-1-4277-9553
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23
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Wang F, Jing Y, Wang Z, Mao T, Samaj J, Yuan M, Ren H. Arabidopsis profilin isoforms, PRF1 and PRF2 show distinctive binding activities and subcellular distributions. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2009; 51:113-21. [PMID: 19200149 DOI: 10.1111/j.1744-7909.2008.00781.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Profilin is an actin-binding protein that shows complex effects on the dynamics of the actin cytoskeleton. There are five profilin isoforms in Arabidopsis thaliana L. However, it is still an open question whether these isoforms are functionally different. In the present study, two profilin isoforms from Arabidopsis, PRF1 and PRF2 were fused with green fluorescent protein (GFP) tag and expressed in Escherichia coli and A. thaliana in order to compare their biochemical properties in vitro and their cellular distributions in vivo. Biochemical analysis revealed that fusion proteins of GFP-PRF1 and GFP-PRF2 can bind to poly-L-proline and G-actin showing remarkable differences. GFP-PRF1 has much higher affinities for both poly-L-proline and G-actin compared with GFP-PRF2. Observations of living cells in stable transgenic A. thaliana lines revealed that 35S::GFP-PRF1 formed a filamentous network, while 35S::GFP-PRF2 formed polygonal meshes. Results from the treatment with latrunculin A and a subsequent recovery experiment indicated that filamentous alignment of GFP-PRF1 was likely associated with actin filaments. However, GFP-PRF2 localized to polygonal meshes resembling the endoplasmic reticulum. Our results provide evidence that Arabidopsis profilin isoforms PRF1 and PRF2 have different biochemical affinities for poly-L-proline and G-actin, and show distinctive localizations in living cells. These data suggest that PRF1 and PRF2 are functionally different isoforms.
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Affiliation(s)
- Feng Wang
- State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, China
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24
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Xie L, Forer A. Jasplakinolide, an actin stabilizing agent, alters anaphase chromosome movements in crane-fly spermatocytes. ACTA ACUST UNITED AC 2008; 65:876-89. [DOI: 10.1002/cm.20309] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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25
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Momma K, Masuzawa Y, Nakai N, Chujo M, Murakami A, Kioka N, Kiyama Y, Akita T, Nagao M. Direct interaction of Cucurbitacin E isolated from Alsomitra macrocarpa to actin filament. Cytotechnology 2007; 56:33-9. [PMID: 19002839 DOI: 10.1007/s10616-007-9100-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Accepted: 09/19/2007] [Indexed: 11/26/2022] Open
Abstract
A methanol extract of Alsomitra macrocarpa leaves and branches induced a marked alteration of cell morphology in a human stellate cell line (LX-2). Similar morphologic alterations were observed in several other cell lines. Active compound was purified from the extract and determined to be cucurbitacin E (Cuc E). It has been known that Cuc E causes marked disruption of the actin cytoskeleton, supporting our observation, but how Cuc E altered the actin cytoskeleton has not been elucidated. By using the standard fluorescence assay using copolymerization and depolymerization of native and pyrene labelled actin, this study revealed that Cuc E interacted directly with actin consequently stabilizing the polymerized actin. When NIH-3T3 cells exogenously expressing YFP-labeled actin were treated with Cuc E, firstly the aggregation of globular actin and secondly the aggregation of actin including disrupted fibrous actin in the cells was observed.
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Affiliation(s)
- Keiko Momma
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502, Japan
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26
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Amin M, Grove DA, Kapus A, Glogauer M, Ellen RP. An actin-stabilizing peptide conjugate deduced from the major outer sheath protein of the bacterium Treponema denticola. ACTA ACUST UNITED AC 2007; 64:662-74. [PMID: 17565753 DOI: 10.1002/cm.20213] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A synthetic peptide conjugated to bovine serum albumin, P34(BSA), based on a 10-mer in the deduced amino acid sequence of the major outer sheath protein of Treponema denticola, was found to stabilize actin filaments of fibroblasts. Pretreatment of cells with P34(BSA) inhibited the actin disruption induced by cytochalasin D and latrunculin B. P34(BSA) was taken up by the cells and localized among actin filaments. P34(BSA) bound actin from fibroblast lysates, and cell exposure to P34(BSA) led to the activation of RhoA, a key regulator of actin filament assembly in fibroblasts. Exposure of fibroblasts to P34(BSA) retarded their migration on a collagen substratum. P34(BSA) also inhibited chemotaxis of murine neutrophils. Our findings with a novel peptide conjugate imply that bacterial proteins known to perturb the cytoskeleton represent a rich source of molecular models upon which to design synthetic reagents for modulating actin-dependent cellular functions.
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Affiliation(s)
- Mohsen Amin
- CIHR Group in Matrix Dynamics and Dental Research Institute, University of Toronto, Toronto, Ontario, Canada
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27
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Holzinger A, Wasteneys GO, Lütz C. Investigating cytoskeletal function in chloroplast protrusion formation in the arctic-alpine plant Oxyria digyna. PLANT BIOLOGY (STUTTGART, GERMANY) 2007; 9:400-10. [PMID: 17236103 DOI: 10.1055/s-2006-924727] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Arctic and alpine plants like Oxyria digyna have to face enhanced environmental stress. This study compared leaves from Oxyria digyna collected in the Arctic at Svalbard (78 degrees N) and in the Austrian Alps (47 degrees N) at cellular, subcellular, and ultrastructural levels. Oxyria digyna plants collected in Svalbard had significantly thicker leaves than the samples collected in the Austrian Alps. This difference was generated by increased thickness of the palisade and spongy mesophyll layers in the arctic plants, while epidermal cells had no significant size differences between the two habitats. A characteristic feature of arctic, alpine, and cultivated samples was the occurrence of broad stroma-filled chloroplast protrusions, 2 - 5 microm broad and up to 5 microm long. Chloroplast protrusions were in close spatial contact with other organelles including mitochondria and microbodies. Mitochondria were also present in invaginations of the chloroplasts. A dense network of cortical microtubules found in the mesophyll cells suggested a potential role for microtubules in the formation and function of chloroplast protrusions. No direct interactions between microtubules and chloroplasts, however, were observed and disruption of the microtubule arrays with the anti-microtubule agent oryzalin at 5 - 10 microM did not alter the appearance or dynamics of chloroplast protrusions. These observations suggest that, in contrast to studies on stromule formation in Nicotiana, microtubules are not involved in the formation and morphology of chloroplast protrusions in Oxyria digyna. The actin microfilament-disrupting drug latrunculin B (5 - 10 microM for 2 h) arrested cytoplasmic streaming and altered the cytoplasmic integrity of mesophyll cells. However, at the ultrastructural level, stroma-containing, thylakoid-free areas were still visible, mostly at the concave sides of the chloroplasts. As chloroplast protrusions were frequently found to be mitochondria-associated in Oxyria digyna, a role in metabolite exchange is possible, which may contribute to an adaptation to alpine and arctic conditions.
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Affiliation(s)
- A Holzinger
- Department of Physiology and Cell Physiology of Alpine Plants, Institute of Botany, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria.
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Cárdenas L, Lovy-Wheeler A, Wilsen KL, Hepler PK. Actin polymerization promotes the reversal of streaming in the apex of pollen tubes. ACTA ACUST UNITED AC 2005; 61:112-27. [PMID: 15849722 DOI: 10.1002/cm.20068] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Actin polymerization is important in the control of pollen tube growth. Thus, treatment of pollen tubes with low concentrations of latrunculin B (Lat-B), which inhibits actin polymerization, permits streaming but reversibly blocks oscillatory growth. In the current study, we employ Jasplakinolide (Jas), a sponge cyclodepsipeptide that stabilizes actin microfilaments and promotes polymerization. Uniquely, Jas (2 microM) blocks streaming in the shank of the tube, but induces the formation of a toroidal-shaped domain in the swollen apex, of which longitudinal optical sections exhibit circles of motion. The polarity of this rotary motion is identical to that of reverse fountain motility in control pollen tubes, with the forward direction occurring at the edge of the cell and the rearward direction in the cell interior. Support for the idea that actin polymerization in the apical domain contributes to the formation of this rotary motility activity derives from the appearance therein of aggregates and flared cables of F-actin, using immunofluorescence, and by the reduction in G-actin as indicated with fluorescent DNAse. In addition, Jas reduces the tip-focused Ca2+ gradient. However, the alkaline band appears in the swollen apex and is spatially localized with the reverse fountain streaming activity. Taken together, our results support the idea that actin polymerization promotes reversal of streaming in the apex of the lily pollen tube.
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Affiliation(s)
- Luis Cárdenas
- Biology Department, and the Plant Biology Graduate Program, Morrill Science Center, University of Massachusetts, Amherst, USA.
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29
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Rosestolato CTF, Dutra JDMF, De Souza W, de Carvalho TMU. Participation of host cell actin filaments during interaction of trypomastigote forms of Trypanosoma cruzi with host cells. Cell Struct Funct 2002; 27:91-8. [PMID: 12207050 DOI: 10.1247/csf.27.91] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The involvement of actin filaments from the host cell on the process of invasion of trypomastigote forms of Trypanosma cruzi was analyzed in seven different cell lines. Prior incubation of all cell lines with cytochalasin D, under conditions which interfere with actin filaments, markedly inhibited parasite internalization and increased parasite attachment. Attached parasites were readily ingested following washing of the drug-treated cells. Cytochalasin treatment interfered with the distribution of actin filaments of the host cell as evaluated by visualization of the filaments using confocal laser scanning microscopy of cells incubated in the presence of FITC-phalloidin. Concentration of actin filaments could be observed in most, but not all, parasites in the process of internalization. We also treated LLCMK 2 and macrophage cells with Jasplakinolide, a drug that stabilizes actin filaments, before interaction with the trypomastigote forms. This drug partially inhibits parasite invasion into the cells. Prior incubation of the host cells in the presence of colchicine, which interfere with microtubules, also inhibited parasite internalization into the cells.
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Affiliation(s)
- Carlos Tadeu Fonseca Rosestolato
- Laboratório de Biologia Celular e Tecidual, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Rio de Janeiro, RJ, Brazil
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30
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Isowa N, Liu M. Role of LPS-induced microfilament depolymerization in MIP-2 production from rat pneumocytes. Am J Physiol Lung Cell Mol Physiol 2001; 280:L762-70. [PMID: 11238018 DOI: 10.1152/ajplung.2001.280.4.l762] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have previously demonstrated that lipopolysaccharide (LPS) induces production of macrophage inflammatory protein-2 (MIP-2), a C-X-C chemokine for neutrophil recruitment and activation, in primary cultured rat lung alveolar epithelial cells. We have also demonstrated that LPS depolymerizes microfilaments in rat alveolar epithelial cells. To determine whether the polymerization status of microfilaments affects LPS-induced MIP-2 production, we treated rat alveolar epithelial cells with cytochalasin D (CytoD), a microfilament-disrupting agent, before and during LPS stimulation. A lower concentration (0.1 microM) of CytoD inhibited LPS-induced MIP-2 production without affecting microfilament polymerization. In contrast, LPS-induced MIP-2 production was enhanced by a higher concentration (10 microM) of CytoD, which disrupted the filamentous structure of actin. Jasplakinolide (1 nM to 1 microM), a polymerizing agent for microfilaments, decreased LPS-induced MIP-2 secretion. Jasplakinolide (1 microM) also blocked LPS-induced depolymerization of microfilaments. These results suggest that, in alveolar epithelial cells, LPS-induced MIP-2 production is at least partially regulated by microfilament depolymerization.
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Affiliation(s)
- N Isowa
- Thoracic Surgery Research Laboratory, Division of Cellular and Molecular Biology, Toronto General Hospital Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada M5G 2C4
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White SR, Williams P, Wojcik KR, Sun S, Hiemstra PS, Rabe KF, Dorscheid DR. Initiation of apoptosis by actin cytoskeletal derangement in human airway epithelial cells. Am J Respir Cell Mol Biol 2001; 24:282-94. [PMID: 11245627 DOI: 10.1165/ajrcmb.24.3.3995] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Changes in epithelial cell shape can lead to cell death and detachment. Actin filaments are cleaved during apoptosis, but whether disruption in the actin cytoskeletal network, as one manifestation of cell shape change, can itself induce apoptosis is not known. We tested this hypothesis in the airway epithelial cell line 1HAEo(-) and in primary airway epithelial cells by preventing actin filament elongation with cytochalasin D or by aggregating actin filaments with jasplakinolide. Disruption of actin filament integrity promptly induced apoptosis in adherent epithelial cells within 5 h. Jasplakinolide-induced apoptosis did not disrupt focal adhesions, whereas cytochalasin D-induced apoptosis decreased focal adhesion protein expression and occurred despite ligation of the fibronectin receptor. Death induction was abrogated by the caspase inhibitors z-VAD-fmk and Ac-DEVD-cho but not by blocking the Fas (CD95) receptor. Whereas cytochalasin D--induced apoptosis was associated with cleavage of pro-caspase-8, jasplakinolide-induced apoptosis was not. Both agents induced formation of a death-inducing signaling complex. These data demonstrate that disruption of actin filament integrity with either cytochalasin D or jasplakinolide induces apoptosis in airway epithelial cells but by different mechanisms, and suggest that actin may be an early modulator of apoptotic commitment.
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Affiliation(s)
- S R White
- Section of Pulmonary and Critical Care Medicine, Department of Medicine, Division of Biological Sciences, University of Chicago, Chicago, Illinois 60637, USA.
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32
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Holzinger A, Lütz-Meindl U. Chondramides, novel cyclodepsipeptides from myxobacteria, influence cell development and induce actin filament polymerization in the green alga Micrasterias. CELL MOTILITY AND THE CYTOSKELETON 2001; 48:87-95. [PMID: 11169761 DOI: 10.1002/1097-0169(200102)48:2<87::aid-cm1000>3.0.co;2-c] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The effects of chondramides A-D, new actin targeting cyclodepsipeptides from the myxobacterium Chondromyces crocatus, are probed on the unicellular green alga Micrasterias denticulata, a model organism for studies on cytomorphogenesis. All four chondramides readily enter the cells and cause severe shape malformations when applied during growth. However, the four derivatives have different lowest effective concentrations. Chondramide A: 20 microM, chondramide B: 15 microM, chondramide C: 5 microM chondramide D: 10 microM. At the ultrastructural level, chondramide C, the most effective drug, causes the appearance of abnormal, dense F-actin bundles, and a substantial increase in ER, which covers large parts of the developing semicell. Also the secondary cell wall is malformed by the drug. When chondramide C effects are investigated by means of indirect immunofluorescence, alterations of the F-actin system are also visible. Instead of the cortical F-actin network of untreated controls, distinct parts of the cell are covered by abundant F-actin aggregations. Phalloidin staining of chondramide C treated cells results in a decreased fluorescence in a time-dependent manner due to binding competitions between these drugs. F-actin polymerizing and bundling capacities of chondramides A-D are presented in Micrasterias for the first time, and may in future make this substances a useful tool for cell biological research.
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Affiliation(s)
- A Holzinger
- Institute of Plant Physiology, University of Salzburg, Austria.
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Odaka C, Sanders ML, Crews P. Jasplakinolide induces apoptosis in various transformed cell lines by a caspase-3-like protease-dependent pathway. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2000; 7:947-52. [PMID: 11063504 PMCID: PMC95991 DOI: 10.1128/cdli.7.6.947-952.2000] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To clarify the mechanisms underlying the antiproliferative effects of jasplakinolide, a cyclic depsipeptide from marine sponges, we examined whether jasplakinolide induces apoptosis in a variety of transformed and nontransformed cells. Jasplakinolide inhibited proliferation of human Jurkat T cells, resulting in cell death. This was accompanied by chromatin condensation and DNA cleavage at the linker regions between the nucleosomes. When caspase-3-like activity in the cytosolic extracts of Jurkat T cells was examined with a fluorescent substrate, DEVD-MAC (N-acetyl-Asp-Glu-Val-Asp-4-methyl-coumaryl-7-amide), the activity in the cells treated with jasplakinolide was remarkably increased in a time-dependent manner. Pretreatment of Jurkat T cells with the caspase inhibitor zVAD [benzyloxycarbonyl(Cbz)-Val-Ala-beta-Asp(OMe)-fluoromethylketone] or DEVD-CHO (N-acetyl-Asp-Glu-Val-Asp-1-aldehyde) prevented the induction of apoptosis by jasplakinolide. Moreover, exposure of various murine transformed cell lines to jasplakinolide resulted in cell death, which was inhibited by zVAD. Although it has been well established that murine immature thymocytes are sensitive to apoptosis when exposed to various apoptotic stimuli, these cells as well as mature T lymphocytes were resistant to jasplakinolide-induced apoptosis. The results suggest that jasplakinolide induces apoptotic cell death through a caspase-3-like protease-dependent pathway. Another important outcome is that transformed cell lines were more susceptible to jasplakinolide-induced apoptosis than normal nontransformed cells.
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Affiliation(s)
- C Odaka
- Department of Bacterial and Blood Products, National Institute of Infectious Diseases, Tokyo, Japan.
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34
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Locker JK, Kuehn A, Schleich S, Rutter G, Hohenberg H, Wepf R, Griffiths G. Entry of the two infectious forms of vaccinia virus at the plasma membane is signaling-dependent for the IMV but not the EEV. Mol Biol Cell 2000; 11:2497-511. [PMID: 10888684 PMCID: PMC14935 DOI: 10.1091/mbc.11.7.2497] [Citation(s) in RCA: 147] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The simpler of the two infectious forms of vaccinia virus, the intracellular mature virus (IMV) is known to infect cells less efficiently than the extracellular enveloped virus (EEV), which is surrounded by an additional, TGN-derived membrane. We show here that when the IMV binds HeLa cells, it activates a signaling cascade that is regulated by the GTPase rac1 and rhoA, ezrin, and both tyrosine and protein kinase C phosphorylation. These cascades are linked to the formation of actin and ezrin containing protrusions at the plasma membrane that seem to be essential for the entry of IMV cores. The identical cores of the EEV also appear to enter at the cell surface, but surprisingly, without the need for signaling and actin/membrane rearrangements. Thus, in addition to its known role in wrapping the IMV and the formation of intracellular actin comets, the membrane of the EEV seems to have evolved the capacity to enter cells silently, without a need for signaling.
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Affiliation(s)
- J K Locker
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
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35
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Terada Y, Simerly C, Schatten G. Microfilament stabilization by jasplakinolide arrests oocyte maturation, cortical granule exocytosis, sperm incorporation cone resorption, and cell-cycle progression, but not DNA replication, during fertilization in mice. Mol Reprod Dev 2000; 56:89-98. [PMID: 10737971 DOI: 10.1002/(sici)1098-2795(200005)56:1<89::aid-mrd11>3.0.co;2-i] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Jasplakinolide (JAS), which induces microfilament polymerization and stabilization, inhibits microfilament-mediated events in murine oocyte maturation and fertilization in a fashion unlike the effects of cytochalasin B (CCB) and latranculin A (LAT A). JAS prevents egg polar body emission at a much lower concentration than either CCB or LAT A. Microfilament bundles were detected on the entire egg cortex after JAS exposure. Conversely, microfilament patterns did not change after exposure to CCB, and few microfilaments were observed after exposure to LAT A. Eggs that were allowed to recover from JAS were unable to recover normal microfilament organization. During oocyte maturation, JAS prevented both spindle migration to the oocyte cortex and first polar body emission. During in vitro fertilization, sperm head entered the eggs and formed pronuclei, but sperm tail entry, pronuclear centration, and second polar body emission were not detected. DNA synthesis occurs in these JAS-treated zygotes. JAS inhibited not only the formation, but also the disassembly, of incorporation cones. JAS was also found to prevent cortical granule exocytosis following artificial activation, and cortical granules were still beneath the plasma membrane even after activation. Finally, incorporation of microinjected nonmuscle actin into the microfilament network of mice eggs was delayed by JAS. We conclude that JAS acts as a microfilament inhibitor during maturation and fertilization and is more powerful than other inhibitors. Its mechanism differs in that it promotes assembly and stabilization of microfilaments. JAS is a novel cell permeable tool for the investigation of microfilament-dependent events in early mammalian development.
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Affiliation(s)
- Y Terada
- Department of Cell-Developmental Biology and Obstetrics and Gynecology, Oregon Health Sciences University, Beaverton, Oregon
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36
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Bubb MR, Spector I, Beyer BB, Fosen KM. Effects of jasplakinolide on the kinetics of actin polymerization. An explanation for certain in vivo observations. J Biol Chem 2000; 275:5163-70. [PMID: 10671562 DOI: 10.1074/jbc.275.7.5163] [Citation(s) in RCA: 406] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Jasplakinolide paradoxically stabilizes actin filaments in vitro, but in vivo it can disrupt actin filaments and induce polymerization of monomeric actin into amorphous masses. A detailed analysis of the effects of jasplakinolide on the kinetics of actin polymerization suggests a resolution to this paradox. Jasplakinolide markedly enhances the rate of actin filament nucleation. This increase corresponds to a change in the size of actin oligomer capable of nucleating filament growth from four to approximately three subunits, which is mechanistically consistent with the localization of the jasplakinolide-binding site at an interface of three actin subunits. Because jasplakinolide both decreases the amount of sequestered actin (by lowering the critical concentration of actin) and augments nucleation, the enhancement of polymerization by jasplakinolide is amplified in the presence of actin-monomer sequestering proteins such as thymosin beta(4). Overall, the kinetic parameters in vitro define the mechanism by which jasplakinolide induces polymerization of monomeric actin in vivo. Expected consequences of jasplakinolide function are consistent with the experimental observations and include de novo nucleation resulting in disordered polymeric actin and in insufficient monomeric actin to allow for remodeling of stress fibers.
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Affiliation(s)
- M R Bubb
- Department of Medicine, University of Florida, Gainesville, Florida 32610, USA
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37
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Raucher D, Stauffer T, Chen W, Shen K, Guo S, York JD, Sheetz MP, Meyer T. Phosphatidylinositol 4,5-bisphosphate functions as a second messenger that regulates cytoskeleton-plasma membrane adhesion. Cell 2000; 100:221-8. [PMID: 10660045 DOI: 10.1016/s0092-8674(00)81560-3] [Citation(s) in RCA: 530] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Binding interactions between the plasma membrane and the cytoskeleton define cell functions such as cell shape, formation of cell processes, cell movement, and endocytosis. Here we use optical tweezers tether force measurements and show that plasma membrane phosphatidylinositol 4,5-bisphosphate (PIP2) acts as a second messenger that regulates the adhesion energy between the cytoskeleton and the plasma membrane. Receptor stimuli that hydrolyze PIP2 lowered adhesion energy, a process that could be mimicked by expressing PH domains that sequester PIP2 or by targeting a 5'-PIP2-phosphatase to the plasma membrane to selectively lower plasma membrane PIP2 concentration. Our study suggests that plasma membrane PIP2 controls dynamic membrane functions and cell shape by locally increasing and decreasing the adhesion between the actin-based cortical cytoskeleton and the plasma membrane.
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Affiliation(s)
- D Raucher
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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38
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Cramer LP. Role of actin-filament disassembly in lamellipodium protrusion in motile cells revealed using the drug jasplakinolide. Curr Biol 1999; 9:1095-105. [PMID: 10531004 DOI: 10.1016/s0960-9822(99)80478-3] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND In motile cells, protrusion of the lamellipodium (a type of cell margin) requires assembly of actin monomers into actin filaments at the tip of the lamellipodium. The importance of actin-filament disassembly in this process is less well understood, and is assessed here using the actin drug jasplakinolide, which has two known activities - inhibition of filament disassembly and induction of an increase in actin polymer. RESULTS In cells the two activities of jasplakinolide were found to be separable; 1 microM jasplakinolide could permeate cells, bind cellular filamentous actin (F-actin) and inhibit filament disassembly within 3.5 minutes, but significant increase in actin polymer was not detected until 60 minutes of treatment. In live, permeabilised cells, jasplakinolide did not inhibit filament assembly from supplied, purified actin monomers. In migrating chick fibroblasts, lamellipodium protrusion was blocked within 1-5 minutes of treatment with 1 microM jasplakinolide, without any perturbation of actin organisation. In non-migrating chick fibroblasts, there was a delay in the onset of jasplakinolide-induced inhibition of lamellipodium protrusion, during which lamellipodium length increased linearly with no increase in protrusion rate. Motility of the bacterium Listeria in infected PtK2 cells was reduced 2.3-fold within 3 minutes of treatment with 1 microM jasplakinolide. CONCLUSIONS Actin-filament disassembly is tightly coupled to lamellipodium protrusion in migrating chick fibroblasts and motility of Listeria in PtK2 cells. One simple interpretation of these data is a situation whereby ongoing actin-filament assembly uses free actin monomer derived from filament disassembly, in preference to stored monomer.
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Affiliation(s)
- L P Cramer
- MRC-Laboratory Molecular Cell Biology University College London Gower Street, WC1E 6BT, The Randall Institute Kings College London, WC2B 5RL, UK.
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39
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Shaw MK, Tilney LG. Induction of an acrosomal process in Toxoplasma gondii: visualization of actin filaments in a protozoan parasite. Proc Natl Acad Sci U S A 1999; 96:9095-9. [PMID: 10430901 PMCID: PMC17738 DOI: 10.1073/pnas.96.16.9095] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The invasive stages of Toxoplasma gondii, an Apicomplexan parasite, actively invade their host cells in an actin-dependent way. However, despite containing biochemically significant amounts of actin, actin filaments have never been observed in these parasites. Jasplakinolide, a membrane-permeable actin-polymerizing and filament-stabilizing drug, induced the polymerization of actin filaments at the anterior end of each tachyzoite in association with the conoid, where they formed, in many cases, a prominent membrane-enclosed apical projection reminiscent of acrosomal processes of invertebrate sperm. These jasplakinolide-induced filaments decorated with myosin subfragment 1, demonstrating unequivocally that they were indeed actin. Jasplakinolide-treated tachyzoites were unable to invade host cells, but once the drug was removed the parasites were able to enter host cells. Actin polymerization at the apical end of the parasite is consistent with the role of the apical end in host-cell invasion powered by a jackhammer-like extension and retraction of the conoid complex coupled to the secretion and rearward capping of surface proteins.
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Affiliation(s)
- M K Shaw
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA.
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40
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Poupel O, Tardieux I. Toxoplasma gondii motility and host cell invasiveness are drastically impaired by jasplakinolide, a cyclic peptide stabilizing F-actin. Microbes Infect 1999; 1:653-62. [PMID: 10611742 DOI: 10.1016/s1286-4579(99)80066-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Actin polymerization and actin-myosin coupling activity most likely provide the driving force that the protozoan parasite Toxoplasma gondii has to exert to propulse itself during gliding and host cell entry. Nevertheless, little information is available on T. gondii tachyzoite actin dynamics, and in particular, the presence of actin filaments remains largely uncharacterized. Here, we report that the marine sponge peptide jasplakinolide, known to bind to filamentous actin, does indeed stabilize a pool of a parasite detergent-insoluble actin. This pool is likely to be formed by a dynamic assembled actin complex: first, it is competent for assembly/disassembly and secondly, it is sensitive to nucleotide phosphate concentration. In addition, T. gondii tachyzoites contain molecules which inhibit actin assembly and destabilize actin filaments. Thus, these activities could account for the remarkably low amount of the myosin-containing F-actin pool we describe here. Furthermore, when parasites are treated with cell-permeant jasplakinolide, they display a significant loss of both motility and host cell invasiveness. These data suggest that in vivo, the detergent-insoluble pool of actin is dynamic.
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Affiliation(s)
- O Poupel
- Institut Pasteur, BBMI, 25-28, rue du Dr Roux, 75724 Paris cedex 15, France
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41
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Sawitzky H, Liebe S, Willingale-Theune J, Menzel D. The anti-proliferative agent jasplakinolide rearranges the actin cytoskeleton of plant cells. Eur J Cell Biol 1999; 78:424-33. [PMID: 10430024 DOI: 10.1016/s0171-9335(99)80085-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the present study, we have characterized the action of the natural cyclodepsipeptide jasplakinolide (JAS) on the cytoplasmic architecture, actin-based cytoplasmic motility, and the organization of the actin cytoskeleton in selected examples of green algae (Acetabularia, Pseudobryopsis and Nitella) and higher plant cells (Allium bulb scale cells and Sinapis root hairs). JAS was capable of influencing the actin cytoskeleton and inhibiting cytoplasmic streaming in a differential, cell type-specific manner. With the exception of Nitella, two consecutive responses were observed upon incubation with 2.5 microM JAS: In the first phase cytoplasmic streaming increased transiently alongside with minor modifications of the actin cytoskeleton in the form of adventitious actin spots and spikes appearing throughout the cell cortex in addition to the normal actin bundle system typical for each cell type. In the second phase, cytoplasmic streaming stopped and the actin cytoskeleton became heavily reorganized into shorter, straight, more and more randomly oriented bundle segments. JAS exerted severe long-term effects on the actin cytoskeleton when treatments exceeded 30min at a concentration of 2.5 microM. An in situ competition assay using equimolar concentrations of JAS and FITC-phalloidin suggested that JAS has a phalloidin-like action. Effects of JAS were significantly different from those of cytochalasin D with respect to the resulting degree of perturbance of cytoplasmic organization, the distribution of actin filaments and the speed of reversibility.
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Affiliation(s)
- H Sawitzky
- Max-Planck-Institut für Zellbiologie, Rosenhof, Ladenburg, Germany
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Alteration of Actin Organization by Jaspamide Inhibits Ruffling, but not Phagocytosis or Oxidative Burst, in HL-60 Cells and Human Monocytes. Blood 1999. [DOI: 10.1182/blood.v93.11.3994] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractJaspamide, a naturally occurring cyclic peptide isolated from the marine sponge Hemiastrella minor, has fungicidal and growth-inhibiting activities. Exposure of promyelocytic HL-60 cells and human monocytes to jaspamide induces a dramatic reorganization of actin from a typical fibrous network to focal aggregates. HL-60 cells exposed to 5 × 10−8 mol/L or 10−7 mol/L jaspamide exhibited a reduced proliferation rate. In addition, 10−7mol/L jaspamide induced maturation of HL-60 cells as indicated by the appearance of a lobulated nucleus in 55% ± 5% of the cells and immunophenotypic maturation of the leukemia cells (upregulation of CD16 and CD14 B antigens). Further characterization has shown that F-actin is aggregated both in HL-60 cells and in human monocytes exposed to 10−7 mol/L jaspamide. Well-spread cultured human monocytes contracted and adopted round shapes after treatment with jaspamide. Moreover, a dose-dependent increase in both total actin and de novo synthesized portions of the soluble actin was observed in jaspamide-treated HL-60 cells. Jaspamide treatment inhibits ruffling and intracellular movement in HL-60 cells and monocytes, but does not affect phagocytic activity or respiratory burst activity. The consequential effects of jaspamide-induced actin reorganization on ruffling, versus its negligible effect on phagocytosis and oxidative burst, may shed light on molecular mechanisms of actin involvement in these processes. Jaspamide disrupts the actin cytoskeleton of normal and malignant mammalian cells with no significant effect on phagocytic activity and may, therefore, be considered as a novel therapeutic agent.
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Alteration of Actin Organization by Jaspamide Inhibits Ruffling, but not Phagocytosis or Oxidative Burst, in HL-60 Cells and Human Monocytes. Blood 1999. [DOI: 10.1182/blood.v93.11.3994.411k39_3994_4005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Jaspamide, a naturally occurring cyclic peptide isolated from the marine sponge Hemiastrella minor, has fungicidal and growth-inhibiting activities. Exposure of promyelocytic HL-60 cells and human monocytes to jaspamide induces a dramatic reorganization of actin from a typical fibrous network to focal aggregates. HL-60 cells exposed to 5 × 10−8 mol/L or 10−7 mol/L jaspamide exhibited a reduced proliferation rate. In addition, 10−7mol/L jaspamide induced maturation of HL-60 cells as indicated by the appearance of a lobulated nucleus in 55% ± 5% of the cells and immunophenotypic maturation of the leukemia cells (upregulation of CD16 and CD14 B antigens). Further characterization has shown that F-actin is aggregated both in HL-60 cells and in human monocytes exposed to 10−7 mol/L jaspamide. Well-spread cultured human monocytes contracted and adopted round shapes after treatment with jaspamide. Moreover, a dose-dependent increase in both total actin and de novo synthesized portions of the soluble actin was observed in jaspamide-treated HL-60 cells. Jaspamide treatment inhibits ruffling and intracellular movement in HL-60 cells and monocytes, but does not affect phagocytic activity or respiratory burst activity. The consequential effects of jaspamide-induced actin reorganization on ruffling, versus its negligible effect on phagocytosis and oxidative burst, may shed light on molecular mechanisms of actin involvement in these processes. Jaspamide disrupts the actin cytoskeleton of normal and malignant mammalian cells with no significant effect on phagocytic activity and may, therefore, be considered as a novel therapeutic agent.
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Posey SC, Bierer BE. Actin stabilization by jasplakinolide enhances apoptosis induced by cytokine deprivation. J Biol Chem 1999; 274:4259-65. [PMID: 9933626 DOI: 10.1074/jbc.274.7.4259] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Participation of the actin cytoskeleton in the transduction of proliferative signals has been established through the use of compounds that disrupt the cytoskeleton. To address the possibility that actin also participates in the transduction of an apoptotic signal, we have studied the response of the murine interleukin 2 (IL-2)-dependent T cell line CTLL-20 to treatment with the actin-binding compound jasplakinolide upon IL-2 deprivation. Like phalloidin, jasplakinolide stabilizes F-actin and promotes actin polymerization. Treatment of CTLL-20 cells with jasplakinolide, in the presence or absence of recombinant human IL-2, altered actin morphology as assessed by confocal fluorescence microscopy. Jasplakinolide was not toxic to CTLL-20 cells, nor was apoptosis induced in the presence of exogenous recombinant human IL-2. However, actin stabilization at the time of IL-2 deprivation enhanced apoptosis by changing the time at which CTLL-20 cells committed to the apoptotic pathway. This effect of jasplakinolide correlated with its ability to stabilize polymerized actin, as treatment with a synthetic analog of jasplakinolide with a greatly reduced ability to bind actin, jasplakinolide B, did not enhance apoptosis. The enhancement occurred upstream of the induction of caspase-3-like activity and could be inhibited by the overexpression of the anti-apoptotic protein Bcl-xL. These data suggest that the actin cytoskeleton plays an active role in modulating lymphocyte apoptosis induced by cytokine deprivation.
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Affiliation(s)
- S C Posey
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachussets 02115, USA
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