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Zhang XM, Xu KL, Kong JH, Dong G, Dong SJ, Yang ZX, Xu SJ, Wang L, Luo SY, Zhang YD, Zhou CC, Gu WY, Mei SY. Heterozygous CAPZA2 mutations cause global developmental delay, hypotonia with epilepsy: a case report and the literature review. J Hum Genet 2024; 69:197-203. [PMID: 38374166 DOI: 10.1038/s10038-024-01230-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 02/05/2024] [Accepted: 02/06/2024] [Indexed: 02/21/2024]
Abstract
CAPZA2 encodes the α2 subunit of CAPZA, which is vital for actin polymerization and depolymerization in humans. However, understanding of diseases associated with CAPZA2 remains limited. To date, only three cases have been documented with neurodevelopmental abnormalities such as delayed motor development, speech delay, intellectual disability, hypotonia, and a history of seizures. In this study, we document a patient who exhibited seizures, mild intellectual disability, and impaired motor development yet did not demonstrate speech delay or hypotonia. The patient also suffered from recurrent instances of respiratory infections, gastrointestinal and allergic diseases. A novel de novo splicing variant c.219+1 G > A was detected in the CAPZA2 gene through whole-exome sequencing. This variant led to exon 4 skipping in mRNA splicing, confirmed by RT-PCR and Sanger sequencing. To our knowledge, this is the third study on human CAPZA2 defects, documenting the fourth unambiguously diagnosed case. Furthermore, this splicing mutation type is reported here for the first time. Our research offers additional support for the existence of a CAPZA2-related non-syndromic neurodevelopmental disorder. Our findings augment our understanding of the phenotypic range associated with CAPZA2 deficiency and enrich the knowledge of the mutational spectrum of the CAPZA2 gene.
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Affiliation(s)
- Xiao-Man Zhang
- Henan Key Laboratory of Children's Genetics and Metabolic Diseases, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Kai-Li Xu
- Department of Pediatric Neurology, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Jing-Hui Kong
- Henan Key Laboratory of Children's Genetics and Metabolic Diseases, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Geng Dong
- Department of Clinical Laboratory, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Shi-Jie Dong
- Department of Radiology, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Zhi-Xiao Yang
- Department of Pediatric Neurology, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Shu-Jing Xu
- Department of Pediatric Neurology, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Li Wang
- Department of Pediatric Neurology, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Shu-Ying Luo
- Henan Key Laboratory of Children's Genetics and Metabolic Diseases, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Yao-Dong Zhang
- Henan Key Laboratory of Children's Genetics and Metabolic Diseases, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Chong-Chen Zhou
- Henan Key Laboratory of Children's Genetics and Metabolic Diseases, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Wei-Yue Gu
- Chigene Translational Medical Research Center Co. Ltd, Beijing, China
| | - Shi-Yue Mei
- Henan Key Laboratory of Children's Genetics and Metabolic Diseases, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China.
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2
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Kramer DA, Narvaez-Ortiz HY, Patel U, Shi R, Shen K, Nolen BJ, Roche J, Chen B. The intrinsically disordered cytoplasmic tail of a dendrite branching receptor uses two distinct mechanisms to regulate the actin cytoskeleton. eLife 2023; 12:e88492. [PMID: 37555826 PMCID: PMC10411975 DOI: 10.7554/elife.88492] [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: 04/10/2023] [Accepted: 05/01/2023] [Indexed: 08/10/2023] Open
Abstract
Dendrite morphogenesis is essential for neural circuit formation, yet the molecular mechanisms underlying complex dendrite branching remain elusive. Previous studies on the highly branched Caenorhabditis elegans PVD sensory neuron identified a membrane co-receptor complex that links extracellular signals to intracellular actin remodeling machinery, promoting high-order dendrite branching. In this complex, the claudin-like transmembrane protein HPO-30 recruits the WAVE regulatory complex (WRC) to dendrite branching sites, stimulating the Arp2/3 complex to polymerize actin. We report here our biochemical and structural analysis of this interaction, revealing that the intracellular domain (ICD) of HPO-30 is intrinsically disordered and employs two distinct mechanisms to regulate the actin cytoskeleton. First, HPO-30 ICD binding to the WRC requires dimerization and involves the entire ICD sequence, rather than a short linear peptide motif. This interaction enhances WRC activation by the GTPase Rac1. Second, HPO-30 ICD directly binds to the sides and barbed end of actin filaments. Binding to the barbed end requires ICD dimerization and inhibits both actin polymerization and depolymerization, resembling the actin capping protein CapZ. These dual functions provide an intriguing model of how membrane proteins can integrate distinct mechanisms to fine-tune local actin dynamics.
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Affiliation(s)
- Daniel A Kramer
- Roy J Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State UniversityAmesUnited States
| | - Heidy Y Narvaez-Ortiz
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of OregonEugeneUnited States
| | - Urval Patel
- Roy J Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State UniversityAmesUnited States
| | - Rebecca Shi
- Department of Biology, Stanford UniversityStanfordUnited States
- Neurosciences IDP, Stanford UniversityStanfordUnited States
| | - Kang Shen
- Department of Biology, Stanford UniversityStanfordUnited States
- Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Brad J Nolen
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of OregonEugeneUnited States
| | - Julien Roche
- Roy J Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State UniversityAmesUnited States
| | - Baoyu Chen
- Roy J Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State UniversityAmesUnited States
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Chuong Nguyen TH, Kim Lien GT, Yen PH, Ho TT, Thuy Van DT, Van Kiem P, Hung NH, Kuo PC, Setzer WN. Molluscicidal Activity of Compounds From the Roots of Aralia armata Against the Golden Apple Snail ( Pomacea canaliculata). Nat Prod Commun 2022. [DOI: 10.1177/1934578x221144573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Background: Aralia armata (Araliaceae) is considered to exhibit effective molluscicidal activity, however, the relationship between the chemical components and molluscicidal activity has not been clearly elucidated. This research attempts to decipher these correlations among the 15 compounds isolated from Vietnam-grown A. armata roots against the freshwater snail, Pomacea canaliculata, a gastropod causing severe damage in agricultural production. Methods: Fifteen saponins were isolated from the methanol root extract of A. armata using chromatographic methods and were identified using spectroscopic techniques. The compounds were screened for molluscicidal activity against P. canaliculata, as well as toxicity against brine shrimp ( Artemia sp.) and phytotoxicity against rice germination and growth. Results: The saponin compounds exhibited extraordinary inhibition of P. canaliculata with LC50 values ranging from 7.90 to 17.50 µg/mL. Notably, the active compounds from A. armata exhibit safety for both nontarget aquatic animals, specifically Artemia sp. with LC50 values between 148.55 and 193.22 µg/mL, and the growth and development of Oryza sativa L. plants showed very little difference compared with the negative control . A molecular docking analysis indicated P. canaliculata acetylcholinesterase (PcAChE) and the actin-binding protein villin (PcVillin) to be potential biomolecular targets of the A. armata saponins. Conclusion: The present experimental and in silico data illustrate the potential of A. armata in agricultural applications.
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Affiliation(s)
- Thi Hong Chuong Nguyen
- Institute of Research and Development, Duy Tan University, Danang, Vietnam
- Faculty of Natural sciences, Duy Tan University, Danang, Vietnam
| | - Giang Thi Kim Lien
- Institute for Research and Executive Education, The University of Danang, Danang, Vietnam
| | - Pham Hai Yen
- Institute of Marine Biochemistry, Vietnam Academy of Science and Technology (VAST), Cau Giay, Hanoi, Vietnam
| | - Thanh-Tam Ho
- Faculty of Natural sciences, Duy Tan University, Danang, Vietnam
- Institute for Global Health Innovations, Duy Tan University, Danang, Vietnam
| | - Do Thi Thuy Van
- University of Science Education, The University of Danang, Danang, Vietnam
| | - Phan Van Kiem
- Institute of Marine Biochemistry, Vietnam Academy of Science and Technology (VAST), Cau Giay, Hanoi, Vietnam
| | - Nguyen Huy Hung
- Institute of Research and Development, Duy Tan University, Danang, Vietnam
- Faculty of Natural sciences, Duy Tan University, Danang, Vietnam
| | - Ping-Chung Kuo
- School of Pharmacy, College of Medicine, National Cheng Kung University, Tainan
| | - William N. Setzer
- Department of Chemistry, University of Alabama in Huntsville, Huntsville, AL, USA
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4
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Scheff DR, Weirich KL, Dasbiswas K, Patel A, Vaikuntanathan S, Gardel ML. Tuning shape and internal structure of protein droplets via biopolymer filaments. SOFT MATTER 2020; 16:5659-5668. [PMID: 32519715 DOI: 10.1039/c9sm02462j] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Macromolecules can phase separate to form liquid condensates, which are emerging as critical compartments in fields as diverse as intracellular organization and soft materials design. A myriad of macromolecules, including the protein FUS, form condensates which behave as isotropic liquids. Here, we investigate the influence of filament dopants on the material properties of protein liquids. We find that the short, biopolymer filaments of actin spontaneously partition into FUS droplets to form composite liquid droplets. As the concentration of the filament dopants increases, the coalescence time decreases, indicating that the dopants control viscosity relative to surface tension. The droplet shape is tunable and ranges from spherical to tactoid as the filament length or concentration is increased. We find that the tactoids are well described by a model of a quasi bipolar liquid crystal droplet, where nematic order from the anisotropic actin filaments competes with isotropic interfacial energy from the FUS, controlling droplet shape in a size-dependent manner. Our results demonstrate a versatile approach to construct tunable, anisotropic macromolecular liquids.
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Affiliation(s)
- Danielle R Scheff
- James Franck Institute, University of Chicago, Chicago, IL 60637, USA. and Department of Physics, University of Chicago, Chicago, IL 60637, USA
| | - Kimberly L Weirich
- James Franck Institute, University of Chicago, Chicago, IL 60637, USA. and HHMI HCIA Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
| | - Kinjal Dasbiswas
- Department of Physics, University of California, Merced, CA 95343, USA
| | - Avinash Patel
- HHMI HCIA Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA and Dewpoint Therapeutics GmbH, Pfotenhauer Strasse 108, Dresden 01307, USA
| | - Suriyanarayanan Vaikuntanathan
- James Franck Institute, University of Chicago, Chicago, IL 60637, USA. and Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
| | - Margaret L Gardel
- James Franck Institute, University of Chicago, Chicago, IL 60637, USA. and Department of Physics, University of Chicago, Chicago, IL 60637, USA and HHMI HCIA Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
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5
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Lee M, Kang EH. Molecular dynamics study of interactions between polymorphic actin filaments and gelsolin segment-1. Proteins 2019; 88:385-392. [PMID: 31498927 DOI: 10.1002/prot.25813] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 08/22/2019] [Accepted: 09/04/2019] [Indexed: 11/08/2022]
Abstract
The assembly of protein actin into double-helical filaments promotes many eukaryotic cellular processes that are regulated by actin-binding proteins (ABPs). Actin filaments can adopt multiple conformations, known as structural polymorphism, which possibly influences the interaction between filaments and ABPs. Gelsolin is a Ca2+ -regulated ABP that severs and caps actin filaments. Gelsolin binding modulates filament structure; however, it is not known how polymorphic actin filament structures influence an interaction of gelsolin S1 with the barbed-end of filament. Herein, we investigated how polymorphic structures of actin filaments affect the interactions near interfaces between the gelsolin segment 1 (S1) domain and the filament barbed-end. Using all-atom molecular dynamics simulations, we demonstrate that different tilted states of subunits modulate gelsolin S1 interactions with the barbed-end of polymorphic filaments. Hydrogen bonding and interaction energy at the filament-gelsolin S1 interface indicate distinct conformations of filament barbed ends, resulting in different interactions of gelsolin S1. This study demonstrates that filament's structural multiplicity plays important roles in the interactions of actin with ABPs.
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Affiliation(s)
- Myeongsang Lee
- NanoScience Technology Center, University of Central Florida, Orlando, Florida
| | - Ellen H Kang
- NanoScience Technology Center, University of Central Florida, Orlando, Florida.,Department of Physics, University of Central Florida, Orlando, Florida.,Department of Materials Science and Engineering, University of Central Florida, Orlando, Florida
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6
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Vasquez MC, Lippert MR, White C, Walter RK, Tomanek L. Proteomic changes across a natural temperature gradient in a marine gastropod. MARINE ENVIRONMENTAL RESEARCH 2019; 149:137-147. [PMID: 31204014 DOI: 10.1016/j.marenvres.2019.06.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 06/01/2019] [Accepted: 06/05/2019] [Indexed: 06/09/2023]
Abstract
Responses of marine ectotherms to variable environmental temperature often entails maintanence of cellular homeostasis and physiological function through temperature compensation and physiological changes. We investigated the physiological response to thermal stress by examining proteomic changes in the marine kelp forest gastropod and emerging fisheries species Kellet's whelk (Kelletia kelletii) across a naturally-existing thermal gradient that ranges from a warmer-water site inside the species' native range and extends to the northern, cold-water edge of the range. We hypothesized that abundance of cellular stress response and energy metabolism proteins would increase with decreasing temperature in support of cold-compensation. Our exploratory proteomic analysis of whelk gill tissue (N = 6 whelks) from each of the four California Channel Island sites revealed protein abundance changes related to the cytoskeleton, energy metabolism/oxidative stress, and cell signaling. The changes did not correlate consistently with temperature. Nonetheless, whelks from the coldest island site showed increased abundance of energy metabolism and oxidative stress proteins, possibly suggesting oxidative damage of lipid membranes that is ameliorated by antioxidants and may aid in their cold stress response. Similarly, our exploratory analysis revealed abundances of cell signaling proteins that were higher at the coldest site compared to the warmest site, possibly indicating an importance for cell signaling regulation in relatively cooler environments. This study provides protein targets for future studies related to thermal effects in marine animals and may contribute to understanding the physiological response of marine organisms to future ocean conditions.
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Affiliation(s)
- M Christina Vasquez
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA, 93407, USA.
| | - Marilla R Lippert
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA, 93407, USA
| | - Crow White
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA, 93407, USA
| | - Ryan K Walter
- Physics Department, California Polytechnic State University, San Luis Obispo, CA, 93407, USA
| | - Lars Tomanek
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA, 93407, USA
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7
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Interplay of structure, elasticity, and dynamics in actin-based nematic materials. Proc Natl Acad Sci U S A 2017; 115:E124-E133. [PMID: 29284753 DOI: 10.1073/pnas.1713832115] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Achieving control and tunability of lyotropic materials has been a long-standing goal of liquid crystal research. Here we show that the elasticity of a liquid crystal system consisting of a dense suspension of semiflexible biopolymers can be manipulated over a relatively wide range of elastic moduli. Specifically, thin films of actin filaments are assembled at an oil-water interface. At sufficiently high concentrations, one observes the formation of a nematic phase riddled with [Formula: see text] topological defects, characteristic of a two-dimensional nematic system. As the average filament length increases, the defect morphology transitions from a U shape into a V shape, indicating the relative increase of the material's bend over splay modulus. Furthermore, through the sparse addition of rigid microtubule filaments, one can gain additional control over the liquid crystal's elasticity. We show how the material's bend constant can be raised linearly as a function of microtubule filament density, and present a simple means to extract absolute values of the elastic moduli from purely optical observations. Finally, we demonstrate that it is possible to predict not only the static structure of the material, including its topological defects, but also the evolution of the system into dynamically arrested states. Despite the nonequilibrium nature of the system, our continuum model, which couples structure and hydrodynamics, is able to capture the annihilation and movement of defects over long time scales. Thus, we have experimentally realized a lyotropic liquid crystal system that can be truly engineered, with tunable mechanical properties, and a theoretical framework to capture its structure, mechanics, and dynamics.
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8
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Abstract
The actin cytoskeleton is a critical regulator of cytoplasmic architecture and mechanics, essential in a myriad of physiological processes. Here we demonstrate a liquid phase of actin filaments in the presence of the physiological cross-linker, filamin. Filamin condenses short actin filaments into spindle-shaped droplets, or tactoids, with shape dynamics consistent with a continuum model of anisotropic liquids. We find that cross-linker density controls the droplet shape and deformation timescales, consistent with a variable interfacial tension and viscosity. Near the liquid-solid transition, cross-linked actin bundles show behaviors reminiscent of fluid threads, including capillary instabilities and contraction. These data reveal a liquid droplet phase of actin, demixed from the surrounding solution and dominated by interfacial tension. These results suggest a mechanism to control organization, morphology, and dynamics of the actin cytoskeleton.
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9
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Westfalewicz B, Dietrich MA, Ciereszko A. Impact of cryopreservation on bull () semen proteome. J Anim Sci 2016; 93:5240-53. [PMID: 26641044 DOI: 10.2527/jas.2015-9237] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cryopreservation of bull spermatozoa is a well-established technique, allowing artificial insemination of cattle on a commercial scale. However, the extent of proteome changes in seminal plasma and spermatozoa during cryopreservation are not yet fully known. The objective of this study was to compare the proteomes of fresh, equilibrated, and cryopreserved bull semen (spermatozoa and seminal plasma) to establish the changes in semen proteins during the cryopreservation process. Semen was collected from 6 mature Holstein Friesian bulls. After sample processing, comparative analysis and identification of proteins was performed using 2-dimensional difference in-gel electrophoresis coupled with matrix-assisted laser desorption/ionization mass spectrometry. Analysis of spermatozoa extracts revealed that 25 identified protein spots, representing 16 proteins, underwent significant ( < 0.05) changes in abundance due to equilibration and cryopreservation. Eighteen protein spots decreased in abundance, 5 protein spots increased in abundance, and 2 protein spots showed different, specific patterns of abundance changes. Analysis of seminal fluid containing seminal plasma showed that 6 identified protein spots, representing 4 proteins, underwent significant ( < 0.05) changes in abundance due to equilibration and cryopreservation. Two protein spots increased in abundance and 4 decreased in abundance. Semen extending and equilibration seems to be responsible for a significant portion of the proteome changes related to cryopreservation technology. Most sperm proteins affected by equilibration and cryopreservation are membrane bound, and loss of those proteins may reduce natural spermatozoa coating. Further research is needed to unravel the mechanisms of the particular protein changes described in this study and establish the relationship between those changes and sperm quality.
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10
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Manhart A, Schmeiser C. Existence of and decay to equilibrium of the filament end density along the leading edge of the lamellipodium. J Math Biol 2016; 74:169-193. [PMID: 27206776 PMCID: PMC5206285 DOI: 10.1007/s00285-016-1027-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 05/04/2016] [Indexed: 12/04/2022]
Abstract
A model for the dynamics of actin filament ends along the leading edge of the lamellipodium is analyzed. It contains accounts of nucleation by branching, of deactivation by capping, and of lateral flow along the leading edge by polymerization. A nonlinearity arises from a Michaelis–Menten type modeling of the branching process. For branching rates large enough compared to capping rates, the existence and stability of nontrivial steady states is investigated. The main result is exponential convergence to nontrivial steady states, proven by investigating the decay of an appropriate Lyapunov functional.
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Affiliation(s)
- Angelika Manhart
- CIMS, New York University, 251 Mercer Street, New York, NY, 10012, USA.
- Faculty of Mathematics, University of Vienna, Oskar-Morgenstern Platz 1, 1090, Vienna, Austria.
| | - Christian Schmeiser
- Faculty of Mathematics, University of Vienna, Oskar-Morgenstern Platz 1, 1090, Vienna, Austria
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11
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Augustine SM, Cherian AV, Syamaladevi DP, Subramonian N. Erianthus arundinaceus HSP70 (EaHSP70) Acts as a Key Regulator in the Formation of Anisotropic Interdigitation in Sugarcane (Saccharum spp. hybrid) in Response to Drought Stress. PLANT & CELL PHYSIOLOGY 2015; 56:2368-80. [PMID: 26423958 DOI: 10.1093/pcp/pcv142] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 09/22/2015] [Indexed: 05/07/2023]
Abstract
Plant growth during abiotic stress is a long sought-after trait especially in crop plants in the context of global warming and climate change. Previous studies on leaf epidermal cells have revealed that during normal growth and development, adjacent cells interdigitate anisotropically to form cell morphological patterns known as interlocking marginal lobes (IMLs), involving the cell wall-cell membrane-cortical actin continuum. IMLs are growth-associated cell morphological changes in which auxin-binding protein (ABP), Rho GTPases and actin are known to play important roles. In the present study, we investigated the formation of IMLs under drought stress and found that Erianthus arundinaceus, a drought-tolerant wild relative of sugarcane, develops such growth-related cell morphological patterns under drought stress. Using confocal microscopy, we showed an increasing trend in cortical F-actin intensity in drought-tolerant plants with increasing soil moisture stress. In order to check the role of drought tolerance-related genes in IML formation under soil moisture stress, we adopted a structural data mining strategy and identified indirect connections between the ABPs and heat shock proteins (HSPs). Initial experimental evidence for this connection comes from the high transcript levels of HSP70 observed in drought-stressed Erianthus, which developed anisotropic interdigitation, i.e. IMLs. Subsequently, by overexpressing the E. arundinaceus HSP70 gene (EaHSP70) in sugarcane (Saccharum spp. hybrid), we confirm the role of HSP70 in the formation of anisotropic interdigitation under drought stress. Taken together, our results suggest that EaHSP70 acts as a key regulator in the formation of anisotropic interdigitation in drought-tolerant plants (Erianthus and HSP70 transgenic sugarcane) under moisture stress in an actin-mediated pathway. The possible biological significance of the formation of drought-associated interlocking marginal lobes (DaIMLs) in sugarcane plants upon drought stress is discussed.
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Affiliation(s)
| | - Anoop V Cherian
- Present address: Max Planck Institute for Heart and Lungs Research, Bad Nauheim, Germany.
| | - Divya P Syamaladevi
- Sugarcane Breeding Institute, ICAR, Coimbatore 641007, India Present address: Indian Institute of Rice Research, ICAR, Hyderabad, India.
| | - N Subramonian
- Sugarcane Breeding Institute, ICAR, Coimbatore 641007, India
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12
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An extended Filament Based Lamellipodium Model produces various moving cell shapes in the presence of chemotactic signals. J Theor Biol 2015; 382:244-58. [DOI: 10.1016/j.jtbi.2015.06.044] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 05/21/2015] [Accepted: 06/26/2015] [Indexed: 11/18/2022]
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13
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Wang S, Hu B, Si W, Jia L, Zheng X, Zhou J. Avibirnavirus VP4 Protein Is a Phosphoprotein and Partially Contributes to the Cleavage of Intermediate Precursor VP4-VP3 Polyprotein. PLoS One 2015; 10:e0128828. [PMID: 26046798 PMCID: PMC4457844 DOI: 10.1371/journal.pone.0128828] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 04/30/2015] [Indexed: 11/19/2022] Open
Abstract
Birnavirus-encoded viral protein 4 (VP4) utilizes a Ser/Lys catalytic dyad mechanism to process polyprotein. Here three phosphorylated amino acid residues Ser538, Tyr611 and Thr674 within the VP4 protein of the infectious bursal disease virus (IBDV), a member of the genus Avibirnavirus of the family Birnaviridae, were identified by mass spectrometry. Anti-VP4 monoclonal antibodies finely mapping to phosphorylated (p)Ser538 and the epitope motif 530PVVDGIL536 were generated and verified. Proteomic analysis showed that in IBDV-infected cells the VP4 was distributed mainly in the cytoskeletal fraction and existed with different isoelectric points and several phosphorylation modifications. Phosphorylation of VP4 did not influence the aggregation of VP4 molecules. The proteolytic activity analysis verified that the pTyr611 and pThr674 sites within VP4 are involved in the cleavage of viral intermediate precursor VP4-VP3. This study demonstrates that IBDV-encoded VP4 protein is a unique phosphoprotein and that phosphorylation of Tyr611 and Thr674 of VP4 affects its serine-protease activity.
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Affiliation(s)
- Sanying Wang
- Key Laboratory of Animal Virology of Ministry of Agriculture, Zhejiang University, Hangzhou, PR China
- Shaoxing Center for Disease Control and Prevention, Shaoxing, PR China
| | - Boli Hu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, PR China
| | - Weiying Si
- Key Laboratory of Animal Virology of Ministry of Agriculture, Zhejiang University, Hangzhou, PR China
| | - Lu Jia
- Key Laboratory of Animal Virology of Ministry of Agriculture, Zhejiang University, Hangzhou, PR China
| | - Xiaojuan Zheng
- Key Laboratory of Animal Virology of Ministry of Agriculture, Zhejiang University, Hangzhou, PR China
- State Key Laboratory and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital, Zhejiang University, Hangzhou, PR China
- * E-mail: (JYZ); (XJZ)
| | - Jiyong Zhou
- Key Laboratory of Animal Virology of Ministry of Agriculture, Zhejiang University, Hangzhou, PR China
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, PR China
- State Key Laboratory and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital, Zhejiang University, Hangzhou, PR China
- * E-mail: (JYZ); (XJZ)
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14
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Schmeiser C, Winkler C. The flatness of Lamellipodia explained by the interaction between actin dynamics and membrane deformation. J Theor Biol 2015; 380:144-55. [PMID: 26002996 DOI: 10.1016/j.jtbi.2015.05.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 04/30/2015] [Accepted: 05/05/2015] [Indexed: 11/28/2022]
Abstract
The crawling motility of many cell types relies on lamellipodia, flat protrusions spreading on flat substrates but (on cells in suspension) also growing into three-dimensional space. Lamellipodia consist of a plasma membrane wrapped around an oriented actin filament meshwork. It is well known that the actin density is controlled by coordinated polymerization, branching, and capping processes, but the mechanisms producing the small aspect ratios of lamellipodia (hundreds of nm thickness vs. several μm lateral and inward extension) remain unclear. The main hypothesis of this work is a strong influence of the local geometry of the plasma membrane on the actin dynamics. This is motivated by observations of co-localization of proteins with I-BAR domains (like IRSp53) with polymerization and branching agents along the membrane. The I-BAR domains are known to bind to the membrane and to prefer and promote membrane curvature. This hypothesis is translated into a stochastic mathematical model where branching and capping rates, and polymerization speeds depend on the local membrane geometry and branching directions are influenced by the principal curvature directions. This requires the knowledge of the deformation of the membrane, being described in a quasi-stationary approximation by minimization of a modified Helfrich energy, subject to the actin filaments acting as obstacles. Simulations with this model predict pieces of flat lamellipodia without any prescribed geometric restrictions.
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Affiliation(s)
- Christian Schmeiser
- Faculty of Mathematics, University of Vienna, Oskar-Morgenstern-Platz 1, 1090 Vienna, Austria; Johann Radon Institute for Computational and Applied Mathematics, Austrian Academy of Sciences, Altenberger Straße 69, 4040 Linz, Austria
| | - Christoph Winkler
- Johann Radon Institute for Computational and Applied Mathematics, Austrian Academy of Sciences, Altenberger Straße 69, 4040 Linz, Austria.
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Elsobky S, Crane AM, Margolis M, Carreon TA, Bhattacharya SK. Review of application of mass spectrometry for analyses of anterior eye proteome. World J Biol Chem 2014; 5:106-114. [PMID: 24921002 PMCID: PMC4050106 DOI: 10.4331/wjbc.v5.i2.106] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 01/16/2014] [Accepted: 03/04/2014] [Indexed: 02/05/2023] Open
Abstract
Proteins have important functional roles in the body, which can be altered in disease states. The eye is a complex organ rich in proteins; in particular, the anterior eye is very sophisticated in function and is most commonly involved in ophthalmic diseases. Proteomics, the large scale study of proteins, has greatly impacted our knowledge and understanding of gene function in the post-genomic period. The most significant breakthrough in proteomics has been mass spectrometric identification of proteins, which extends analysis far beyond the mere display of proteins that classical techniques provide. Mass spectrometry functions as a “mass analyzer” which simplifies the identification and quantification of proteins extracted from biological tissue. Mass spectrometric analysis of the anterior eye proteome provides a differential display for protein comparison of normal and diseased tissue. In this article we present the key proteomic findings in the recent literature related to the cornea, aqueous humor, trabecular meshwork, iris, ciliary body and lens. Through this we identified unique proteins specific to diseases related to the anterior eye.
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Ostler N, Britzen-Laurent N, Liebl A, Naschberger E, Lochnit G, Ostler M, Forster F, Kunzelmann P, Ince S, Supper V, Praefcke GJK, Schubert DW, Stockinger H, Herrmann C, Stürzl M. Gamma interferon-induced guanylate binding protein 1 is a novel actin cytoskeleton remodeling factor. Mol Cell Biol 2014; 34:196-209. [PMID: 24190970 PMCID: PMC3911287 DOI: 10.1128/mcb.00664-13] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/22/2013] [Accepted: 10/28/2013] [Indexed: 02/07/2023] Open
Abstract
Gamma interferon (IFN-γ) regulates immune defenses against viruses, intracellular pathogens, and tumors by modulating cell proliferation, migration, invasion, and vesicle trafficking processes. The large GTPase guanylate binding protein 1 (GBP-1) is among the cellular proteins that is the most abundantly induced by IFN-γ and mediates its cell biologic effects. As yet, the molecular mechanisms of action of GBP-1 remain unknown. Applying an interaction proteomics approach, we identified actin as a strong and specific binding partner of GBP-1. Furthermore, GBP-1 colocalized with actin at the subcellular level and was both necessary and sufficient for the extensive remodeling of the fibrous actin structure observed in IFN-γ-exposed cells. These effects were dependent on the oligomerization and the GTPase activity of GBP-1. Purified GBP-1 and actin bound to each other, and this interaction was sufficient to impair the formation of actin filaments in vitro, as demonstrated by atomic force microscopy, dynamic light scattering, and fluorescence-monitored polymerization. Cosedimentation and band shift analyses demonstrated that GBP-1 binds robustly to globular actin and slightly to filamentous actin. This indicated that GBP-1 may induce actin remodeling via globular actin sequestering and/or filament capping. These results establish GBP-1 as a novel member within the family of actin-remodeling proteins specifically mediating IFN-γ-dependent defense strategies.
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Affiliation(s)
- Nicole Ostler
- Division of Molecular and Experimental Surgery, University Medical Center Erlangen, Friedrich Alexander University of Erlangen-Nuremberg, Erlangen, Germany
| | - Nathalie Britzen-Laurent
- Division of Molecular and Experimental Surgery, University Medical Center Erlangen, Friedrich Alexander University of Erlangen-Nuremberg, Erlangen, Germany
| | - Andrea Liebl
- Division of Molecular and Experimental Surgery, University Medical Center Erlangen, Friedrich Alexander University of Erlangen-Nuremberg, Erlangen, Germany
| | - Elisabeth Naschberger
- Division of Molecular and Experimental Surgery, University Medical Center Erlangen, Friedrich Alexander University of Erlangen-Nuremberg, Erlangen, Germany
| | - Günter Lochnit
- Faculty of Medicine, Institute of Biochemistry, Justus Liebig University, Giessen, Germany
| | - Markus Ostler
- Institute of Physics, Chemnitz University of Technology, Chemnitz, Germany
| | - Florian Forster
- Molecular Immunology Unit, Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Peter Kunzelmann
- Institute of Polymer Materials, Friedrich Alexander University of Erlangen-Nuremberg, Erlangen, Germany
| | - Semra Ince
- Physical Chemistry I, Ruhr University Bochum, Bochum, Germany
| | - Verena Supper
- Molecular Immunology Unit, Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | | | - Dirk W. Schubert
- Institute of Polymer Materials, Friedrich Alexander University of Erlangen-Nuremberg, Erlangen, Germany
| | - Hannes Stockinger
- Molecular Immunology Unit, Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | | | - Michael Stürzl
- Division of Molecular and Experimental Surgery, University Medical Center Erlangen, Friedrich Alexander University of Erlangen-Nuremberg, Erlangen, Germany
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Schroeter MM, Orlova A, Egelman EH, Beall B, Chalovich JM. Organization of F-actin by Fesselin (avian smooth muscle synaptopodin 2). Biochemistry 2013; 52:4955-61. [PMID: 23789719 PMCID: PMC3842371 DOI: 10.1021/bi4005254] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Fesselin or avian synaptopodin 2 is a member of the synaptopodin family of actin binding proteins. Fesselin promotes G-actin polymerization and the formation of large actin complexes that can be collected by low-speed centrifugation. Because of the potential role of fesselin in some cancers and its effects on actin, we further investigated the effect of fesselin on actin. Fesselin initiated actin polymerization under a variety of conditions, including the virtual absence of salt. Actin filaments formed at low salt concentrations in the presence of fesselin were similar to filaments polymerized in the presence of 100 mM KCl. In both cases, the filaments were long and straight with a common orientation. Highly ordered actin bundles formed with increasing times of incubation. Blockers of actin growth at the barbed end (cytochalasin D and CapZ) did not prevent fesselin from polymerizing actin. Low concentrations of fesselin increased the critical concentration of actin. Both observations are consistent with preferential growth at the pointed end of actin filaments. These results indicate a role of fesselin in organizing cellular actin. These and other results indicate that fesselin is part of a cellular actin organizing center.
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Affiliation(s)
- Mechthild M. Schroeter
- Institute of Vegetative Physiology University of Cologne, Robert Koch Strasse 39, D-50931 Cologne, Germany Phone: +49-221-478-7855 Fax: +49-221-478-3538
| | - Albina Orlova
- Department of Biochemistry and Molecular Genetics University of Virginia Box 800733 Charlottesville, VA 22908-0733 Phone: 434-924-8210 Fax: 434-924-5069
| | - Edward H. Egelman
- Department of Biochemistry and Molecular Genetics University of Virginia Box 800733 Charlottesville, VA 22908-0733 Phone: 434-924-8210 Fax: 434-924-5069
| | - Brent Beall
- Department of Biotechnology Athens Technical College 800 US HWY 29N Athens, GA 30601 Phone: 706-227-5350 Fax: 706-425-3104
| | - Joseph M. Chalovich
- Department of Biochemistry & Molecular Biology Brody School of Medicine at East Carolina University 600 Moye Blvd. Greenville, NC 27834-4300, USA Phone: 252-744-2973
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Arora PD, Wang Y, Bresnick A, Dawson J, Janmey PA, McCulloch CA. Collagen remodeling by phagocytosis is determined by collagen substrate topology and calcium-dependent interactions of gelsolin with nonmuscle myosin IIA in cell adhesions. Mol Biol Cell 2013; 24:734-47. [PMID: 23325791 PMCID: PMC3596245 DOI: 10.1091/mbc.e12-10-0754] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cell adhesion to collagen presented on beads activates Ca2+ entry and promotes the formation of phagosomes enriched with NMMIIA and gelsolin. The Ca2+-dependent interaction of gelsolin and NMMIIA in turn enables actin remodeling and enhances collagen degradation by phagocytosis. We examine how collagen substrate topography, free intracellular calcium ion concentration ([Ca2+]i, and the association of gelsolin with nonmuscle myosin IIA (NMMIIA) at collagen adhesions are regulated to enable collagen phagocytosis. Fibroblasts plated on planar, collagen-coated substrates show minimal increase of [Ca2+]i, minimal colocalization of gelsolin and NMMIIA in focal adhesions, and minimal intracellular collagen degradation. In fibroblasts plated on collagen-coated latex beads there are large increases of [Ca2+]i, time- and Ca2+-dependent enrichment of NMMIIA and gelsolin at collagen adhesions, and abundant intracellular collagen degradation. NMMIIA knockdown retards gelsolin recruitment to adhesions and blocks collagen phagocytosis. Gelsolin exhibits tight, Ca2+-dependent binding to full-length NMMIIA. Gelsolin domains G4–G6 selectively require Ca2+ to interact with NMMIIA, which is restricted to residues 1339–1899 of NMMIIA. We conclude that cell adhesion to collagen presented on beads activates Ca2+ entry and promotes the formation of phagosomes enriched with NMMIIA and gelsolin. The Ca2+ -dependent interaction of gelsolin and NMMIIA in turn enables actin remodeling and enhances collagen degradation by phagocytosis.
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Affiliation(s)
- P D Arora
- Faculty of Dentistry, University of Toronto, Toronto, ON, Canada
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20
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Arora PD, Wang Y, Janmey PA, Bresnick A, Yin HL, McCulloch CA. Gelsolin and non-muscle myosin IIA interact to mediate calcium-regulated collagen phagocytosis. J Biol Chem 2011; 286:34184-98. [PMID: 21828045 DOI: 10.1074/jbc.m111.247783] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The formation of adhesion complexes is the rate-limiting step for collagen phagocytosis by fibroblasts, but the role of Ca(2+) and the potential interactions of actin-binding proteins in regulating collagen phagocytosis are not well defined. We found that the binding of collagen beads to fibroblasts was temporally and spatially associated with actin assembly at nascent phagosomes, which was absent in gelsolin null cells. Analysis of tryptic digests isolated from gelsolin immunoprecipitates indicated that non-muscle (NM) myosin IIA may bind to gelsolin. Immunostaining and immunoprecipitation showed that gelsolin and NM myosin IIA associated at collagen adhesion sites. Gelsolin and NM myosin IIA were both required for collagen binding and internalization. Collagen binding to cells initiated a prolonged increase of [Ca(2+)](i), which was absent in cells null for gelsolin or NM myosin IIA. Collagen bead-induced increases of [Ca(2+)](i) were associated with phosphorylation of the myosin light chain, which was dependent on gelsolin. NM myosin IIA filament assembly, which was dependent on myosin light chain phosphorylation and increased [Ca(2+)](i), also required gelsolin. Ionomycin-induced increases of [Ca(2+)](i) overcame the block of myosin filament assembly in gelsolin null cells. We conclude that gelsolin and NM myosin IIA interact at collagen adhesion sites to enable NM myosin IIA filament assembly and localized, Ca(2+)-dependent remodeling of actin at the nascent phagosome and that these steps are required for collagen phagocytosis.
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Affiliation(s)
- Pamma D Arora
- Matrix Dynamics Group, University of Toronto, Toronto, Ontario M5S 3E2, Canada
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Louzao MC, Ares IR, Cagide E, Espiña B, Vilariño N, Alfonso A, Vieytes MR, Botana LM. Palytoxins and cytoskeleton: An overview. Toxicon 2011; 57:460-9. [DOI: 10.1016/j.toxicon.2010.09.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 09/23/2010] [Accepted: 09/28/2010] [Indexed: 11/30/2022]
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Regulation of myofibroblast activities: calcium pulls some strings behind the scene. Exp Cell Res 2010; 316:2390-401. [PMID: 20451515 DOI: 10.1016/j.yexcr.2010.04.033] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 04/27/2010] [Accepted: 04/30/2010] [Indexed: 12/23/2022]
Abstract
Myofibroblast-induced remodeling of collagenous extracellular matrix is a key component of our body's strategy to rapidly and efficiently repair damaged tissues; thus myofibroblast activity is considered crucial in assuring the mechanical integrity of vital organs and tissues after injury. Typical examples of beneficial myofibroblast activities are scarring after myocardial infarct and repair of damaged connective tissues including dermis, tendon, bone, and cartilage. However, deregulation of myofibroblast contraction causes the tissue deformities that characterize hypertrophic scars as well as organ fibrosis that ultimately leads to heart, lung, liver and kidney failure. The phenotypic features of the myofibroblast, within a spectrum going from the fibroblast to the smooth muscle cell, raise the question as to whether it regulates contraction in a fibroblast- or muscle-like fashion. In this review, we attempt to elucidate this point with a particular focus on the role of calcium signaling. We suggest that calcium plays a central role in myofibroblast biological activity not only in regulating contraction but also in mediating intracellular and extracellular mechanical signals, structurally organizing the contractile actin-myosin cytoskeleton, and establishing lines of intercellular communication.
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Cantiello HF, Montalbetti N, Li Q, Chen XZ. The Cytoskeletal Connection to Ion Channels as a Potential Mechanosensory Mechanism: Lessons from Polycystin-2 (TRPP2). CURRENT TOPICS IN MEMBRANES 2007; 59:233-96. [PMID: 25168140 DOI: 10.1016/s1063-5823(06)59010-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Mechanosensitivity of ion channels, or the ability to transfer mechanical forces into a gating mechanism of channel regulation, is split into two main working (not mutually exclusive) hypotheses. One is that elastic and/or structural changes in membrane properties act as a transducing mechanism of channel regulation. The other hypothesis involves tertiary elements, such as the cytoskeleton which, itself by dynamic interactions with the ion channel, may convey conformational changes, including those ascribed to mechanical forces. This hypothesis is supported by numerous instances of regulatory changes in channel behavior by alterations in cytoskeletal structures/interactions. However, only recently, the molecular nature of these interactions has slowly emerged. Recently, a surge of evidence has emerged to indicate that transient receptor potential (TRP) channels are key elements in the transduction of a variety of environmental signals. This chapter describes the molecular linkage and regulatory elements of polycystin-2 (PC2), a TRP-type (TRPP2) nonselective cation channel whose mutations cause autosomal dominant polycystic kidney disease (ADPKD). The chapter focuses on the involvement of cytoskeletal structures in the regulation of PC2 and discusses how these connections are the transducing mechanism of environmental signals to its channel function.
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Affiliation(s)
- Horacio F Cantiello
- Renal Unit, Massachusetts General Hospital East, Charlestown, Massachusetts 02129; Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115; Laboratorio de Canales Iónicos, Departamento de Fisicoquímica y Química Analítica, Facultad de Farmacia y Bioquímica, Buenos Aires 1113, Argentina
| | - Nicolás Montalbetti
- Laboratorio de Canales Iónicos, Departamento de Fisicoquímica y Química Analítica, Facultad de Farmacia y Bioquímica, Buenos Aires 1113, Argentina
| | - Qiang Li
- Department of Physiology, University of Alberta, Edmonton T6G 2H7, Canada
| | - Xing-Zhen Chen
- Department of Physiology, University of Alberta, Edmonton T6G 2H7, Canada
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Ducibella T, Matson S. Secretory mechanisms and Ca2+ signaling in gametes: similarities to regulated neuroendocrine secretion in somatic cells and involvement in emerging pathologies. Endocr Pathol 2007; 18:191-203. [PMID: 18247164 DOI: 10.1007/s12022-007-0015-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Recent studies demonstrate that regulated secretion in probably all mammalian cells, from gonadotropes to gametes, utilizes similar signaling systems, intracellular Ca(2+) regulation, Ca(2+)-dependent proteins, cytoskeletal participation, and SNARE-mediated fusion. Thus, highly specialized cells, like sperm and eggs, should no longer be considered to have evolved a cell-type specific secretory mechanism. In gametes, Ca(2+)-dependent proteins and enzymes transduce elevations of intracellular Ca(2+) into secretory events, i.e., exocytosis of the acrosome in sperm and cortical granules in the egg. Just as secretory deficiencies have clinical consequences in endocrine and exocrine cells, failure of secretion of cortical granules or the acrosome can result in failure of normal fertilization or fertilization followed by abnormal development. With the advent of human in vitro fertilization, such gamete pathologies have been recently identified and have led to new clinical procedures to achieve normal fertilization and pregnancies. A better understanding of the common Ca(2+)-dependent secretory pathways in both gametes and somatic cells should be beneficial to investigating mis-regulation in either cell type.
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Affiliation(s)
- Tom Ducibella
- Sackler School of Biomedical Sciences, Program in Cell, Molecular, and Developmental Biology, Tufts University School of Medicine, Boston, MA, 0211, USA.
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Kim S, Kim H, Chang B, Ahn N, Hwang S, Di Paolo G, Chang S. Regulation of transferrin recycling kinetics by PtdIns[4,5]P2 availability. FASEB J 2006; 20:2399-401. [PMID: 17012244 DOI: 10.1096/fj.05-4621fje] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PtdIns[4,5]P2) is a phosphoinositide involved in a variety of cellular functions, including signal transduction, organelle trafficking, and actin dynamics. Although the role of PtdIns[4,5]P2 in endocytosis is well established, the precise trafficking steps relying on normal PtdIns[4,5]P2 balance in the endosomal pathway have not yet been elucidated. Here we show that decrease in intracellular PtdIns[4,5]P2 levels achieved by the overexpression of the 5-phosphatase domain of synaptojanin 1 or by siRNA knock-down of PIP5Ks expression lead to severe defects in the internalization of transferrin as well as in the recycling of internalized transferrin back to the cell surface in COS-7 cells. These defects suggest that PtdIns[4,5]P2 participates in multiple trafficking and/or sorting events during endocytosis. Coexpression of the PtdIns[4,5]P2 synthesizing enzyme, PIP5KI gamma, was able to rescue these endocytic defects. Furthermore, decreased levels of PtdIns[4,5]P2 caused delays in rapid and slow membrane recycling pathways as well as a severe backup of endocytosed membrane. Taken together, our results demonstrate that PtdIns[4,5]P2 availability regulates multiple steps in the endocytic cycle in non-neuronal cells.
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Affiliation(s)
- Sunyun Kim
- Department of Life Science, Gwangju Institute of Science and Technology, 1 Oryong-dong Buk-gu, Gwangju, South Korea
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Mohri K, Ono K, Yu R, Yamashiro S, Ono S. Enhancement of actin-depolymerizing factor/cofilin-dependent actin disassembly by actin-interacting protein 1 is required for organized actin filament assembly in the Caenorhabditis elegans body wall muscle. Mol Biol Cell 2006; 17:2190-9. [PMID: 16525019 PMCID: PMC1446098 DOI: 10.1091/mbc.e05-11-1016] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Regulated disassembly of actin filaments is involved in several cellular processes that require dynamic rearrangement of the actin cytoskeleton. Actin-interacting protein (AIP) 1 specifically enhances disassembly of actin-depolymerizing factor (ADF)/cofilin-bound actin filaments. In vitro, AIP1 actively disassembles filaments, caps barbed ends, and binds to the side of filaments. However, how AIP1 functions in the cellular actin cytoskeletal dynamics is not understood. We compared biochemical and in vivo activities of mutant UNC-78 proteins and found that impaired activity of mutant UNC-78 proteins to enhance disassembly of ADF/cofilin-bound actin filaments is associated with inability to regulate striated organization of actin filaments in muscle cells. Six functionally important residues are present in the N-terminal beta-propeller, whereas one residue is located in the C-terminal beta-propeller, suggesting the presence of two separate sites for interaction with ADF/cofilin and actin. In vitro, these mutant UNC-78 proteins exhibited variable alterations in actin disassembly and/or barbed end-capping activities, suggesting that both activities are important for its in vivo function. These results indicate that the actin-regulating activity of AIP1 in cooperation with ADF/cofilin is essential for its in vivo function to regulate actin filament organization in muscle cells.
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Affiliation(s)
- Kurato Mohri
- Department of Pathology, Emory University, Atlanta, GA 30322, USA
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Helfer E, Nevalainen EM, Naumanen P, Romero S, Didry D, Pantaloni D, Lappalainen P, Carlier MF. Mammalian twinfilin sequesters ADP-G-actin and caps filament barbed ends: implications in motility. EMBO J 2006; 25:1184-95. [PMID: 16511569 PMCID: PMC1422163 DOI: 10.1038/sj.emboj.7601019] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Accepted: 02/02/2006] [Indexed: 11/09/2022] Open
Abstract
Twinfilins are conserved actin-binding proteins composed of two actin depolymerizing factor homology (ADF-H) domains. Twinfilins are involved in diverse morphological and motile processes, but their mechanism of action has not been elucidated. Here, we show that mammalian twinfilin both sequesters ADP-G-actin and caps filament barbed ends with preferential affinity for ADP-bound ends. Twinfilin replaces capping protein and promotes motility of N-WASP functionalized beads in a biomimetic motility assay, indicating that the capping activity supports twinfilin's function in motility. Consistently, in vivo twinfilin localizes to actin tails of propelling endosomes. The ADP-actin-sequestering activity cooperates with the filament capping activity of twinfilin to finely regulate motility due to processive filament assembly catalyzed by formin-functionalized beads. The isolated ADF-H domains do not cap barbed ends nor promote motility, but sequester ADP-actin, the C-terminal domain showing the highest affinity. A structural model for binding of twinfilin to barbed ends is proposed based on the similar foldings of twinfilin ADF-H domains and gelsolin segments.
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Affiliation(s)
- Emmanuèle Helfer
- Cytoskeleton Dynamics and Motility, LEBS, CNRS, Gif-sur-Yvette, France
| | | | | | - Stéphane Romero
- Cytoskeleton Dynamics and Motility, LEBS, CNRS, Gif-sur-Yvette, France
| | - Dominique Didry
- Cytoskeleton Dynamics and Motility, LEBS, CNRS, Gif-sur-Yvette, France
| | | | - Pekka Lappalainen
- Institute of Biotechnology, University of Helsinki, Finland
- Institute of Biotechnology, University of Helsinki, Finland. Tel.: +358 9 191 59499; E-mail:
| | - Marie-France Carlier
- Cytoskeleton Dynamics and Motility, LEBS, CNRS, Gif-sur-Yvette, France
- Dynamique du Cytosquelette, LEBS, CNRS, Gif-sur-Yvette F-91198, France. Tel.: +33 1 69 82 34 65; Fax: +33 1 69 82 341 29; E-mail:
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Kataoka M, Kido JI, Shinohara Y, Nagata T. Drug-induced gingival overgrowth--a review. Biol Pharm Bull 2006; 28:1817-21. [PMID: 16204928 DOI: 10.1248/bpb.28.1817] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Drug-induced gingival overgrowth is a side effect associated with 3 types of drugs: anticonvulsants (phenytoin), immunosuppressive agents (cyclosporine A), and various calcium channel blockers for cardiovascular diseases. Gingival overgrowth is characterized by the accumulation of extracellular matrix in gingival connective tissues, particularly collagenous components with various degrees of inflammation. Although the mechanisms of these disorders have not been elucidated, recent studies suggest that these disorders seem to be induced by the disruption of homeostasis of collagen synthesis and degradation in gingival connective tissue, predominantly through the inhibition of collagen phagocytosis of gingival fibroblasts. The integrins are a large family of heterodimeric transmembrane receptors for extracellular matrix molecules. alpha2beta1 integrin serves as a specific receptor for type I collagen on fibroblasts, and alpha2 integrin has been shown to play a crucial role in collagen phagocytosis. Actin filaments, which are assembled from monomers and oligomers, are involved in collagen internalization after binding to integrins. Furthermore, the implication of intracellular calcium in the regulation of integrin-mediated binding activity and gelsolin activity, known as a calcium-dependent actin-severing protein, is also described. In this review, we focus on collagen metabolism in drug-induced gingival overgrowth, focusing on the regulation of collagen phagocytosis in fibroblasts.
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Affiliation(s)
- Masatoshi Kataoka
- Division of Gene Expression, Institute for Genome Research, The University of Tokushima; 3-18-15 Kuramoto, Tokushima 770-8503, Japan.
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Arora PD, Chan MWC, Anderson RA, Janmey PA, McCulloch CA. Separate functions of gelsolin mediate sequential steps of collagen phagocytosis. Mol Biol Cell 2005; 16:5175-90. [PMID: 16120646 PMCID: PMC1266417 DOI: 10.1091/mbc.e05-07-0648] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Collagen phagocytosis is a critical mediator of extracellular matrix remodeling. Whereas the binding step of collagen phagocytosis is facilitated by Ca2+-dependent, gelsolin-mediated severing of actin filaments, the regulation of the collagen internalization step is not defined. We determined here whether phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] regulation of gelsolin is required for collagen internalization. In gelsolin null fibroblasts transfected with gelsolin severing mutants, actin severing and collagen binding were strongly impaired but internalization and actin monomer addition at collagen bead sites were much less affected. PI(4,5)P2 accumulated around collagen during internalization and was associated with gelsolin. Cell-permeable peptides mimicking the PI(4,5)P2 binding site of gelsolin blocked actin monomer addition, the association of gelsolin with actin at phagosomes, and collagen internalization but did not affect collagen binding. Collagen beads induced recruitment of type 1 gamma phosphatidylinositol phosphate kinase (PIPK1gamma661) to internalization sites. Dominant negative constructs and RNA interference demonstrated a requirement for catalytically active PIPK1gamma661 for collagen internalization. We conclude that separate functions of gelsolin mediate sequential stages of collagen phagocytosis: Ca2+-dependent actin severing facilitates collagen binding, whereas PI(4,5)P2-dependent regulation of gelsolin promotes the actin assembly required for internalization of collagen fibrils.
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Affiliation(s)
- P D Arora
- Canadian Institutes of Health Research Group in Matrix Dynamics, University of Toronto, Toronto, Ontario M5S 3E2, Canada
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31
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Lu TS, Chen HW, Huang MH, Wang SJ, Yang RC. Heat shock treatment protects osmotic stress-induced dysfunction of the blood-brain barrier through preservation of tight junction proteins. Cell Stress Chaperones 2005; 9:369-77. [PMID: 15633295 PMCID: PMC1065276 DOI: 10.1379/csc-45r1.1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The blood-brain barrier (BBB) is a specialized structure in the central nervous system (CNS), which participates in maintenance of a state of cerebrospinal fluid homeostasis. The endothelial cells of the cerebral capillaries and the tight junctions between them form the basis of the BBB. Research has shown that destruction of the BBB is associated with diseases of the CNS. However, there is little research on how the BBB might be protected. In this study, we used a high osmotic solution (1.6 M D-mannitol) to open the BBB of rats and Evans blue dye as a macromolecular marker. The effect of heat shock treatment was evaluated. The results show that increased synthesis of heat shock protein 72 (Hsp72) was induced in the heated group only. BBB permeability was significantly less in the heat shock-treated group after hyperosmotic shock. The major tight junction proteins, occludin and zonula occludens (ZO)-1, were significantly decreased after D-mannitol treatment in the nonheated group, whereas they were preserved in the heated group. The coimmunoprecipitation studies demonstrated that Hsp72 could be detected in the precipitates of brain extract interacting with anti-ZO-1 antibodies as well as those interacting with anti-occludin antibodies in the heated group. We conclude that the integrity of tight junctions could be maintained by previous heat shock treatment, which might be associated with the increased production of Hsp72.
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Affiliation(s)
- Tzong-Shi Lu
- Department of Physiology, Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung City 807, Taiwan, Republic of China
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32
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Abstract
Amyloid diseases result from protein misfolding and aggregation into fibrils. Some features of gelsolin amyloidogenic fragments comprised of residues 173-243 (G173-243) and residues 173-202 (G173-202) were investigated by the method of molecular dynamics (MD). The alpha-helical structure of G173-243 present in the whole protein unwinds during the course of MD simulation of the fragment G173-243, suggesting that the G173-243 structure is not stable and could unfold before becoming involved in gelsolin amyloid fibril formation. Twelve fragments of G173-202 were used to build a possible beta-fibril. During the course of the simulation, G173-202 fragments formed hydrogen bonds and tended to turn by an angle of 10 degrees -20 degrees towards each other.
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Affiliation(s)
- Inta Liepina
- Latvian Institute of Organic Synthesis, Aizkraukles str. 21, Riga, LV1006, Latvia.
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33
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Welch AY, Riley KN, D'Souza-Schorey C, Herman IM. Arf6 modulates the beta-actin specific capping protein, betacap73. Methods Enzymol 2005; 404:377-87. [PMID: 16413284 DOI: 10.1016/s0076-6879(05)04033-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Recent work from our laboratory has revealed that isoactin cytoskeletal and membrane dynamics are coordinately regulated. In this chapter, we review some of the recent and relevant scientific literature focusing on key aspects of cytoskeletal and membrane-mediated signal transduction. Additionally, we highlight some of the strategic molecular, biochemical, and cell-based methodologies that we have either developed or implemented in our efforts aimed at revealing the pivotal role(s) that the actin isoforms play in controlling cell shape and motility during developmental and/or disease-associated events. Furthermore, we address the central position of beta-actin and its barbed end-specific capping protein, betacap73, in modulating nonmuscle cell membrane dynamics and cell migration. In studying the molecular mechanisms mediating these cytoskeletal protein interactions, we have recently recognized that cell motility and beta-actin dynamics are controlled by the direct association of betacap73 with the plasma membrane- and endosome-associated protein, ADP-ribosylation factor 6 (Arf6).
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Affiliation(s)
- Alice Y Welch
- NIH-NIAID Office of Technology Development, Bethesda, Maryland, USA
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34
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Abstract
The interaction of particles with certain cell surface receptors initiates intracellular signalling pathways that ultimately lead to submembranous actin filament assembly, pseudopod extension, and the ingestion of the particles. Here, Steven Greenberg reviews recent evidence implicating various signalling events in phagocytosis--in particular, activation of tyrosine kinases and phosphatidylinositol 3-kinase--and speculates how they might regulate the actin cytoskeleton.
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Affiliation(s)
- S Greenberg
- Dept of Medicine, Pulmonary Division, Columbia University College of Physicians & Surgeons, 630 West 168th Street, New York, NY 10032, USA
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35
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Hilpelä P, Vartiainen MK, Lappalainen P. Regulation of the Actin Cytoskeleton by PI(4,5)P2 and PI(3,4,5)P3. Curr Top Microbiol Immunol 2004; 282:117-63. [PMID: 14594216 DOI: 10.1007/978-3-642-18805-3_5] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The actin cytoskeleton is fundamental for various motile and morphogenetic processes in cells. The structure and dynamics of the actin cytoskeleton are regulated by a wide array of actin-binding proteins, whose activities are controlled by various signal transduction pathways. Recent studies have shown that certain membrane phospholipids, especially PI(4,5)P2 and PI(3,4,5)P3, regulate actin filament assembly in cells and in cell extracts. PI(4,5)P2 appears to be a general regulator of actin polymerization at the plasma membrane or at membrane microdomains, whereas PI(3,4,5)P3 promotes the assembly of specialized actin filament structures in response to some growth factors. Biochemical studies have demonstrated that the activities of many proteins promoting actin assembly are upregulated by PI(4,5)P2, whereas proteins that inhibit actin assembly or promote filament disassembly are down-regulated by PI(4,5)P2. PI(3,4,5)P3 promotes its effects on the actin cytoskeleton mainly through activation of the Rho family of small GTPases. In addition to their effects on actin dynamics, both PI(4,5)P2 and PI(3,4,5)P3 promote the formation of specific actin filament structures through activation/inactivation of actin filament cross-linking proteins and proteins that mediate cytoskeleton-plasma membrane interactions.
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Affiliation(s)
- P Hilpelä
- Program in Cellular Biotechnology, Institute of Biotechnology, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland
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36
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Arora PD, Glogauer M, Kapus A, Kwiatkowski DJ, McCulloch CA. Gelsolin mediates collagen phagocytosis through a rac-dependent step. Mol Biol Cell 2003; 15:588-99. [PMID: 14617805 PMCID: PMC329256 DOI: 10.1091/mbc.e03-07-0468] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The role of gelsolin, a calcium-dependent actin-severing protein, in mediating collagen phagocytosis, is not defined. We examined alpha 2 beta 1 integrin-mediated phagocytosis in fibroblasts from wild-type (WT) and gelsolin knockout (Gsn(-)) mice. After initial contact with collagen beads, collagen binding and internalization were 60% lower in Gsn(-) than WT cells. This deficiency was restored by transfection with gelsolin or with beta1 integrin-activating antibodies. WT cells showed robust rac activation and increased [Ca(2+)](i) during early contact with collagen beads, but Gsn(-) cells showed very limited responses. Transfected gelsolin in Gsn(-) cells restored rac activation after collagen binding. Transfection of Gsn(-) cells with active rac increased collagen binding to WT levels. Chelation of intracellular calcium inhibited collagen binding and rac activation, whereas calcium ionophore induced rac activation in WT and Gsn(-) cells. We conclude that the ability of gelsolin to remodel actin filaments is important for collagen-induced calcium entry; calcium in turn is required for rac activation, which subsequently enhances collagen binding to unoccupied alpha 2 beta 1 integrins.
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Affiliation(s)
- Pamela D Arora
- Canadian Institutes of Health Research Group in Matrix Dynamics, University of Toronto, Toronto, Ontario, Canada M5S 3E2
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37
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Sartori MJ, Pons P, Mezzano L, Lin S, de Fabro SP. Trypanosoma cruzi infection induces microfilament depletion in human placenta syncytiotrophoblast. Placenta 2003; 24:767-71. [PMID: 12852867 DOI: 10.1016/s0143-4004(03)00111-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Congenital Chagas disease, endemic in Latin America, is associated with premature labour, miscarriage, and placentitis. Metacyclic trypomastigotes adhere to specific receptors on the outer membrane of host cells as a prelude to intracellular invasion, causing calcium ion mobilization, rearrangement of host cell microfilaments, recruitment of lysosomes and parasite internalization. The actin cytoskeleton plays an important role in many cellular processes including the parasite invasion into mammalian cells. In order to observe if placental cytoskeleton is altered in the process of parasite invasion into placental villi, actin microfilaments were studied. Using immunohistochemical techniques, it was observed that the presence of actin in the syncytiotrophoblast was intense throughout the brush border in control placentae belonging to non-chagasic women. But after culture with the trypomastigote, this labelling disappeared, indicating that the parasite induced disassembly of the cortical actin cytoskeleton when the placenta was infected. As a control, placentae from chagasic women were studied, and no actin was found. The same results were obtained by the electron microscope. We confirmed that cortical actin rearrangements may be an early step in the Trypanosoma cruzi invasion mechanism into placental cells, in order to allow lysosomes access to the plasma membrane, and formation of the parasitophorous vacuole. The recruitment of lysosomes occurs directly beneath the invasion site, and this process is required for parasite internalization.
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Affiliation(s)
- M J Sartori
- IIa. Cátedra de Biología Celular, Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, 5016, Córdoba, Argentina.
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Chu X, Chen J, Reedy MC, Vera C, Sung KLP, Sung LA. E-Tmod capping of actin filaments at the slow-growing end is required to establish mouse embryonic circulation. Am J Physiol Heart Circ Physiol 2003; 284:H1827-38. [PMID: 12543641 DOI: 10.1152/ajpheart.00947.2002] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tropomodulins are a family of proteins that cap the slow-growing end of actin filaments. Erythrocyte tropomodulin (E-Tmod) stabilizes short actin protofilaments in erythrocytes and caps longer sarcomeric actin filaments in striated muscles. We report the knockin of the beta-galactosidase gene (LacZ) under the control of the endogenous E-Tmod promoter and the knockout of E-Tmod in mouse embryonic stem cells. E-Tmod(-/-) embryos die around embryonic day 10 and exhibit a noncontractile heart tube with disorganized myofibrils and underdevelopment of the right ventricle, accumulation of mechanically weakened primitive erythroid cells in the yolk sac, and failure of primary capillary plexuses to remodel into vitelline vessels, all required to establish blood circulation between the yolk sac and the embryo proper. We propose a hemodynamic "plexus channel selection" mechanism as the basis for vitelline vascular remodeling. The defects in cardiac contractility, vitelline circulation, and hematopoiesis reflect an essential role for E-Tmod capping of the actin filaments in both assembly of cardiac sarcomeres and of the membrane skeleton in erythroid cells that is not compensated for by other proteins.
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Affiliation(s)
- Xin Chu
- Department of Bioengineering, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412, USA
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39
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Abstract
The actin cytoskeleton plays a central role in many cell biological processes. The structure and dynamics of the actin cytoskeleton are regulated by numerous actin-binding proteins that usually contain one of the few known actin-binding motifs. WH2 domain (WASP homology domain-2) is a approximately 35 residue actin monomer-binding motif, that is found in many different regulators of the actin cytoskeleton, including the beta-thymosins, ciboulot, WASP (Wiskott Aldrich syndrome protein), verprolin/WIP (WASP-interacting protein), Srv2/CAP (adenylyl cyclase-associated protein) and several uncharacterized proteins. The most highly conserved residues in the WH2 domain are important in beta-thymosin's interactions with actin monomers, suggesting that all WH2 domains may interact with actin monomers through similar interfaces. Our sequence database searches did not reveal any WH2 domain-containing proteins in plants. However, we found three classes of these proteins: WASP, Srv2/CAP and verprolin/WIP in yeast and animals. This suggests that the WH2 domain is an ancient actin monomer-binding motif that existed before the divergence of fungal and animal lineages.
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Affiliation(s)
- Eija Paunola
- Program in Cellular Biotechnology, Institute of Biotechnology, Viikki Biocenter, P.O. Box 56, University of Helsinki, 00014 Helsinki, Finland
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40
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41
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Chellaiah MA, Biswas RS, Yuen D, Alvarez UM, Hruska KA. Phosphatidylinositol 3,4,5-trisphosphate directs association of Src homology 2-containing signaling proteins with gelsolin. J Biol Chem 2001; 276:47434-44. [PMID: 11577104 DOI: 10.1074/jbc.m107494200] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Podosomes are adhesion structures in osteoclasts and are structurally related to focal adhesions mediating cell motility during bone resorption. Here we show that gelsolin coprecipitates some of the focal adhesion-associated proteins such as c-Src, phosphoinositide 3-kinase (PI3K), p130(Cas), focal adhesion kinase, integrin alpha(v)beta(3), vinculin, talin, and paxillin. These proteins were inducibly tyrosine-phosphorylated in response to integrin activation by osteopontin. Previous studies have defined unique biochemical properties of gelsolin related to phosphatidylinositol 3,4,5-trisphosphate in osteoclast podosomes, and here we demonstrate phosphatidylinositol 3,4,5-trisphosphate/gelsolin function in mediating organization of the podosome signaling complex. Overlay and GST pull-down assays demonstrated strong phosphatidylinositol 3,4,5-trisphosphate-PI3K interactions based on the Src homology 2 domains of PI3K. Furthermore, lipid extraction of lysates from activated osteoclasts eliminated interaction between gelsolin, c-Src, PI3K, and focal adhesion kinase despite equal amounts of gelsolin in both the lipid-extracted and unextracted experiment. The cytoplasmic protein tyrosine phosphatase (PTP)-proline-glutamic acid-serine-threonine amino acid sequences (PEST) was also found to be associated with gelsolin in osteoclast podosomes and with stimulation of alpha(v)beta(3)-regulated phosphorylation of PTP-PEST. We conclude that gelsolin plays a key role in recruitment of signaling proteins to the plasma membrane through phospholipid-protein interactions and by regulation of their phosphorylation status through its association with PTP-PEST. Because both gelsolin deficiency and PI3K inhibition impair bone resorption, we conclude that phosphatidylinositol 3,4,5-trisphosphate-based protein interactions are critical for osteoclast function.
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Affiliation(s)
- M A Chellaiah
- Department of Oral and Craniofacial Biological Sciences, University of Maryland, 666 W. Baltimore St., Baltimore, MD 21201, USA.
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42
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Ballweber E, Galla M, Aktories K, Yeoh S, Weeds AG, Mannherz HG. Interaction of ADP-ribosylated actin with actin binding proteins. FEBS Lett 2001; 508:131-5. [PMID: 11707283 DOI: 10.1016/s0014-5793(01)03040-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Actin ADP-ribosylated at Arg177 was previously shown not to polymerise after increasing the ionic strength, but to cap the barbed ends of filaments. Here we confirm that the polymerisation of ADP-ribosylated actin is inhibited, however, under specific conditions the modified actin copolymerises with native actin, indicating that its ability to take part in normal subunit interactions within filaments is not fully eliminated. We also show that ADP-ribosylated actin forms antiparallel but not parallel dimers: the former are not able to form filaments. ADP-ribosylated actin interacts with deoxyribonuclease I, vitamin D binding protein, thymosin beta(4), cofilin and gelsolin segment 1 like native actin. Interaction with myosin subfragment 1 revealed that the potential of the modified actin to aggregate into oligomers or short filaments is not fully eliminated.
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Affiliation(s)
- E Ballweber
- Department of Anatomy and Cell Biology, Ruhr-University, Universitätsstrasse 150, D-44780 Bochum, Germany
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43
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Sawyer SJ, Muscatine L. Cellular mechanisms underlying temperature-induced bleaching in the tropical sea anemone Aiptasia pulchella. J Exp Biol 2001; 204:3443-56. [PMID: 11707495 DOI: 10.1242/jeb.204.20.3443] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Temperature-induced bleaching in symbiotic cnidarians is a result of the detachment and loss of host cells containing symbiotic algae. We tested the hypothesis that host cell detachment is evoked through a membrane thermotropic event causing an increase in intracellular calcium concentration, [Ca2+]i, which could then cause collapse of the cytoskeleton and perturb cell adhesion. Electron paramagnetic resonance measurements of plasma membranes from the tropical sea anemone Aiptasia pulchella and the Hawaiian coral Pocillopora damicornis labeled with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) revealed no membrane thermotropic event. In addition, intracellular imaging using Fura-2AM as well as labeling anemones with 45Ca revealed no significant change in [Ca2+]i. However, bleaching could be evoked at ambient temperature with 25 mmol l–1 caffeine without affecting [Ca2+]i. [Ca2+]i could be altered with ionomycin in isolated host cells, but ionomycin could not induce bleaching in A. pulchella. As caffeine can affect levels of intracellular protein phosphorylation, the ability of other agents that alter intracellular levels of protein phosphorylation to evoke bleaching was investigated. The protein phosphatase inhibitor vanadate could induce bleaching in A. pulchella. Two-dimensional gels of 32P-labeled proteins from cold-shocked, caffeine-treated and control anemones show that both temperature shock and caffeine alter the array of phosphorylated host soluble proteins. We conclude that cnidarian bleaching is linked to a temperature-induced alteration in protein phosphorylation.
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Affiliation(s)
- S J Sawyer
- Department of Organismic Biology, Ecology and Evolution, University of California - Los Angeles, 405 Hilgard Avenue, Los Angeles, CA 90095, USA.
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44
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Friedl P, Borgmann S, Bröcker E. Amoeboid leukocyte crawling through extracellular matrix: lessons from the
Dictyostelium
paradigm of cell movement. J Leukoc Biol 2001. [DOI: 10.1189/jlb.70.4.491] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Peter Friedl
- Cell Migration Laboratory, Department of Dermatology, University of Würzburg, Würzburg, Germany
| | - Stefan Borgmann
- Cell Migration Laboratory, Department of Dermatology, University of Würzburg, Würzburg, Germany
| | - Eva‐B. Bröcker
- Cell Migration Laboratory, Department of Dermatology, University of Würzburg, Würzburg, Germany
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45
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Paddenberg R, Loos S, Schöneberger HJ, Wulf S, Müller A, Iwig M, Mannherz HG. Serum withdrawal induces a redistribution of intracellular gelsolin towards F-actin in NIH 3T3 fibroblasts preceding apoptotic cell death. Eur J Cell Biol 2001; 80:366-78. [PMID: 11432727 DOI: 10.1078/0171-9335-00166] [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: 11/18/2022] Open
Abstract
The intracellular distribution of gelsolin in NIH 3T3 cells was examined by immunostaining using affinity-purified polyclonal gelsolin antibodies before and after induction of apoptosis by serum withdrawal. Serum deprivation induced detachment of an increasing number of NIH 3T3 cells, but also apoptosis in attached cells as verified morphologically by chromatin condensation, nuclear fragmentation and labelling of their periphery by FITC-annexin V. Ongoing apoptosis was also demonstrated by activation of caspase-3 activity and chromatin cleavage into high-molecular-mass fragments, although no internucleosomal chromatin degradation (DNA-ladder formation) was detected. When cells were maintained in the presence of 10% foetal calf serum, gelsolin immunoreactivity was evenly distributed in the cytoplasm. No obvious co-localisation of gelsolin and the actin-containing stress fibres was detected under these conditions. At day one after serum withdrawal, a redistribution of gelsolin to actin filaments was detected within a few attached cells by double fluorescence staining. The number of cells exhibiting this redistribution increased at days two to four. In addition, the stress fibres increased in thickness and their length was continuously reduced. At day four, many cells contained shortened stress fibres, which had lost their longitudinal orientation. Additionally, the cytoplasm of a number of attached cells was highly condensed around their nuclei and a homogenous distribution of both gelsolin and actin was detected in the remaining cytoplasmic rim. Up to day two, these effects were reversible after re-addition of serum to attached cells. A similar redistribution of gelsolin immunore-activity was observed after induction of apoptosis by cycloheximide, but not after initiation of necrosis by hydrogen peroxide. In NIH 3T3 cells no alteration in the expression of gelsolin at the level of protein (Western blot) or specific mRNA (Northern blot) was observed after serum withdrawal. Using Western blotting, no proteolysis of gelsolin was detected up to day 4, although caspase-3 activity was found to have increased fivefold after serum withdrawal. These results suggested that in these cells F-actin severing might occur in the absence or advance of gelsolin cleavage by caspases. Intact gelsolin on its own may be sufficient for the dissolution of the microfilaments, since micro-injection of gelsolin into primary bovine lens cells led to a transient disappearance of the stress fibres and to a reduction of their attachment area to the substratum. In NIH 3T3 cells similar effects of micro-injected gelsolin were only observed at day one after serum withdrawal.
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Affiliation(s)
- R Paddenberg
- Department of Anatomy and Cell Biology, Ruhr-University, Bochum/Germany
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46
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Ebert F, Guillén N, Leippe M, Tannich E. Molecular cloning and cellular localization of an unusual bipartite Entamoeba histolytica polypeptide with similarity to actin binding proteins. Mol Biochem Parasitol 2000; 111:459-64. [PMID: 11163453 DOI: 10.1016/s0166-6851(00)00331-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- F Ebert
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
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47
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Wohnsland F, Steinmetz MO, Aebi U, Vergères G. MARCKS-related protein binds to actin without significantly affecting actin polymerization or network structure. Myristoylated alanine-rich C kinase substrate. J Struct Biol 2000; 131:217-24. [PMID: 11052894 DOI: 10.1006/jsbi.2000.4299] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Actinis a 42-kDa protein which, due to its ability to polymerize into filaments (F-actin), is one of the major constituents of the cytoskeleton. It has been proposed that MARCKS (an acronym for myristoylated alanine-rich C kinase substrate) proteins play an important role in regulating the structure and mechanical properties of the actin cytoskeleton by cross-linking actin filaments. We have recently reported that peptides corresponding to the effector domain of MARCKS proteins promote actin polymerization and cause massive bundling of actin filaments. We now investigate the effect of MARCKS-related protein, a 20-kDa member of the MARCKS family, on both filament structure and the kinetics of actin polymerization in vitro. Our experiments document that MRP binds to F-actin with micromolar affinity and that the myristoyl chain at the N-terminus of MRP is not required for this interaction. In marked contrast to the effector peptide, binding of MRP is not accompanied by an acceleration of actin polymerization kinetics, and we also could not reliably observe an actin cross-linking activity of MRP.
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Affiliation(s)
- F Wohnsland
- Department of Biophysical Chemistry, University of Basel, CH-4056 Basel, Switzerland
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48
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Serrander L, Skarman P, Rasmussen B, Witke W, Lew DP, Krause KH, Stendahl O, Nüsse O. Selective inhibition of IgG-mediated phagocytosis in gelsolin-deficient murine neutrophils. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:2451-7. [PMID: 10946270 DOI: 10.4049/jimmunol.165.5.2451] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phagocytosis and the microbicidal functions of neutrophils require dynamic changes of the actin cytoskeleton. We have investigated the role of gelsolin, a calcium-dependent actin severing and capping protein, in peripheral blood neutrophils from gelsolin-null (Gsn-) mice. The phagocytosis of complement opsonized yeast was only minimally affected. In contrast, phagocytosis of IgG-opsonized yeast was reduced close to background level in Gsn- neutrophils. Thus, gelsolin is essential for efficient IgG- but not complement-mediated phagocytosis. Furthermore, attachment of IgG-opsonized yeast to Gsn- neutrophils was reduced ( approximately 50%) but not to the same extent as ingestion ( approximately 73%). This was not due to reduced surface expression of the Fcgamma-receptor or its lateral mobility. This suggests that attachment and ingestion of IgG-opsonized yeast by murine neutrophils are actin-dependent and gelsolin is important for both steps in phagocytosis. We also investigated granule exocytosis and several steps in phagosome processing, namely the formation of actin around the phagosome, translocation of granules, and activation of the NADPH-oxidase. All these functions were normal in Gsn- neutrophils. Thus, the role of gelsolin is specific for IgG-mediated phagocytosis. Our data suggest that gelsolin is part of the molecular machinery that distinguishes complement and IgG-mediated phagocytosis. The latter requires a more dynamic reorganization of the cytoskeleton.
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Affiliation(s)
- L Serrander
- Divison of Infectious Diseases, University of Geneva, Switzerland.
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49
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Puius YA, Fedorov EV, Eichinger L, Schleicher M, Almo SC. Mapping the functional surface of domain 2 in the gelsolin superfamily. Biochemistry 2000; 39:5322-31. [PMID: 10820002 DOI: 10.1021/bi992364d] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The crystal structure of the F-actin binding domain 2 of severin, the gelsolin homologue from Dictyostelium discoideum, has been determined by multiple isomorphous replacement and refined to 1.75 A resolution. The structure reveals an alpha-helix-beta-sheet sandwich similar to the domains of gelsolin and villin, and contains two cation-binding sites, as observed in other domain 1 and domain 2 homologues. Comparison of the structures of several gelsolin family domains has identified residues that may mediate F-actin binding in gelsolin domain 2 homologues. To assess the involvement of these residues in F-actin binding, three mutants of human gelsolin domain 2 were assayed for F-actin binding activity and thermodynamic stability. Two of the mutants, RRV168AAA and RLK210AAA, demonstrated a lowered affinity for F-actin, indicating a role for those residues in filament binding. Using both structural and biochemical data, we have constructed a model of the gelsolin domain 1-domain 2-F-actin complex. This model highlights a number of interactions that may serve as positive and negative determinants of filament end- and side-binding.
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Affiliation(s)
- Y A Puius
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
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Abstract
Gelsolin is an actin filament severing protein composed of six similar structured domains that differ with respect to actin, calcium and polyphospho-inositide binding. Previous work has established that gelsolin binds tropomyosin [Koepf, E.K. and Burtnick, L.D. (1992) FEBS Lett. 309, 56-58]. We have produced various specific gelsolin domains in Escherichia coli in order to establish which of the six domains binds tropomyosin. Gelsolin domains 1-3 (G1-3), G1-2 and G2 all bind tropomyosin in a pH and calcium insensitive manner whereas binding of G4-6 to tropomyosin was barely detectable under the conditions tested. We conclude that gelsolin binds tropomyosin via domain 2 (G2).
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Affiliation(s)
- S K Maciver
- Genes and Development Group, Department of Biomedical Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, UK.
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