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Flommersfeld J, Stöberl S, Shah O, Rädler JO, Broedersz CP. Geometry-Sensitive Protrusion Growth Directs Confined Cell Migration. Phys Rev Lett 2024; 132:098401. [PMID: 38489624 DOI: 10.1103/physrevlett.132.098401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 01/30/2024] [Indexed: 03/17/2024]
Abstract
The migratory dynamics of cells can be influenced by the complex microenvironment through which they move. It remains unclear how the motility machinery of confined cells responds and adapts to their microenvironment. Here, we propose a biophysical mechanism for a geometry-dependent coupling between cellular protrusions and the nucleus that leads to directed migration. We apply our model to geometry-guided cell migration to obtain insights into the origin of directed migration on asymmetric adhesive micropatterns and the polarization enhancement of cells observed under strong confinement. Remarkably, for cells that can choose between channels of different size, our model predicts an intricate dependence for cellular decision making as a function of the two channel widths, which we confirm experimentally.
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Affiliation(s)
- Johannes Flommersfeld
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, 1081HV Amsterdam, Netherlands
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilian-University Munich, Theresienstraße 37, D-80333 Munich, Germany
| | - Stefan Stöberl
- Faculty of Physics and Center for NanoScience, Ludwig-Maximilian-University, Geschwister-Scholl-Platz 1, D-80539 Munich, Germany
| | - Omar Shah
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, 1081HV Amsterdam, Netherlands
| | - Joachim O Rädler
- Faculty of Physics and Center for NanoScience, Ludwig-Maximilian-University, Geschwister-Scholl-Platz 1, D-80539 Munich, Germany
| | - Chase P Broedersz
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, 1081HV Amsterdam, Netherlands
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilian-University Munich, Theresienstraße 37, D-80333 Munich, Germany
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2
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Bueno C, García-Bernal D, Martínez S, Blanquer M, Moraleda JM. The nuclei of human adult stem cells can move within the cell and generate cellular protrusions to contact other cells. Stem Cell Res Ther 2024; 15:32. [PMID: 38321563 PMCID: PMC10848534 DOI: 10.1186/s13287-024-03638-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 01/17/2024] [Indexed: 02/08/2024] Open
Abstract
BACKGROUND The neuronal transdifferentiation of adult bone marrow cells (BMCs) is still considered an artifact based on an alternative explanation of experimental results supporting this phenomenon obtained over decades. However, recent studies have shown that following neural induction, BMCs enter an intermediate cellular state before adopting neural-like morphologies by active neurite extension and that binucleated BMCs can be formed independent of any cell fusion events. These findings provide evidence to reject the idea that BMC neural transdifferentiation is merely an experimental artifact. Therefore, understanding the intermediate states that cells pass through during transdifferentiation is crucial given their potential application in regenerative medicine and disease modelling. METHODS In this study, we examined the functional significance of the variety of morphologies and positioning that cell nuclei of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) can adopt during neural-like differentiation using live-cell nuclear fluorescence labelling, time-lapse microscopy, and confocal microscopy analysis. RESULTS Here, we showed that after neural induction, hBM-MSCs enter an intermediate cellular state in which the nuclei are able to move within the cells, switching shapes and positioning and even generating cellular protrusions as they attempt to contact the cells around them. These findings suggest that changes in nuclear positioning occur because human cell nuclei somehow sense their environment. In addition, we showed the process of direct interactions between cell nuclei, which opens the possibility of a new level of intercellular interaction. CONCLUSIONS The present study advances the understanding of the intermediate stage through which hBM-MSCs pass during neural transdifferentiation, which may be crucial to understanding the mechanisms of these cell conversion processes and eventually harness them for use in regenerative medicine. Importantly, our study provides for the first time evidence that the nuclei of hBM-MSC-derived intermediate cells somehow sense their environment, generating cellular protrusions to contact other cells. In summary, human mesenchymal stromal cells could not only help to increase our understanding of the mechanisms underlying cellular plasticity but also facilitate the exact significance of nuclear positioning in cellular function and in tissue physiology.
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Affiliation(s)
- Carlos Bueno
- Medicine Department and Hematopoietic Transplant and Cellular Therapy Unit, Faculty of Medicine, Institute of Biomedical Research (IMIB), University of Murcia, 30120, Murcia, Spain.
| | - David García-Bernal
- Medicine Department and Hematopoietic Transplant and Cellular Therapy Unit, Faculty of Medicine, Institute of Biomedical Research (IMIB), University of Murcia, 30120, Murcia, Spain
- Biochemistry, Molecular Biology and Immunology Department, Faculty of Medicine, University of Murcia, 30100, Murcia, Spain
| | - Salvador Martínez
- Instituto de Neurociencias de Alicante (UMH-CSIC), Universidad Miguel Hernandez, 03550, San Juan, Alicante, Spain
- Center of Biomedical Network Research on Mental Health (CIBERSAM), ISCIII, 28029, Madrid, Spain
- Alicante Institute for Health and Biomedical Research (ISABIAL), 03010, Alicante, Spain
| | - Miguel Blanquer
- Medicine Department and Hematopoietic Transplant and Cellular Therapy Unit, Faculty of Medicine, Institute of Biomedical Research (IMIB), University of Murcia, 30120, Murcia, Spain
| | - José M Moraleda
- Medicine Department and Hematopoietic Transplant and Cellular Therapy Unit, Faculty of Medicine, Institute of Biomedical Research (IMIB), University of Murcia, 30120, Murcia, Spain
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3
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Pimenta FM, Huh J, Guzman B, Amanah D, Marston DJ, Pinkin NK, Danuser G, Hahn KM. Rho MultiBinder, a fluorescent biosensor that reports the activity of multiple GTPases. Biophys J 2023; 122:3646-3655. [PMID: 37085995 PMCID: PMC10541480 DOI: 10.1016/j.bpj.2023.04.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 02/28/2023] [Accepted: 04/17/2023] [Indexed: 04/23/2023] Open
Abstract
Imaging two or more fluorescent biosensors in the same living cell can reveal the spatiotemporal coordination of protein activities. However, using multiple Förster resonance energy transfer (FRET) biosensors together is challenging due to toxicity and the need for orthogonal fluorophores. Here we generate a biosensor component that binds selectively to the activated conformation of three different proteins. This enabled multiplexed FRET with fewer fluorophores, and reduced toxicity. We generated this MultiBinder (MB) reagent for the GTPases RhoA, Rac1, and Cdc42 by combining portions of the downstream effector proteins Pak1 and Rhotekin. Using FRET between mCherry on the MB and YPet or mAmetrine on two target proteins, the activities of any pair of GTPases could be distinguished. The MB was used to image Rac1 and RhoA together with a third, dye-based biosensor for Cdc42. Quantifying effects of biosensor combinations on the frequency, duration, and velocity of cell protrusions and retractions demonstrated reduced toxicity. Multiplexed imaging revealed signaling hierarchies between the three proteins at the cell edge where they regulate motility.
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Affiliation(s)
- Frederico M Pimenta
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Jaewon Huh
- Departments of Bioinformatics and Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Bryan Guzman
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Diepreye Amanah
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Daniel J Marston
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Nicholas K Pinkin
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Gaudenz Danuser
- Departments of Bioinformatics and Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Klaus M Hahn
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
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4
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Kapustina M, Li D, Zhu J, Wall B, Weinreb V, Cheney RE. Changes in cell surface excess are coordinated with protrusion dynamics during 3D motility. Biophys J 2023; 122:3656-3677. [PMID: 37207658 PMCID: PMC10541482 DOI: 10.1016/j.bpj.2023.04.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 03/23/2023] [Accepted: 04/20/2023] [Indexed: 05/21/2023] Open
Abstract
To facilitate rapid changes in morphology without endangering cell integrity, each cell possesses a substantial amount of cell surface excess (CSE) that can be promptly deployed to cover cell extensions. CSE can be stored in different types of small surface projections such as filopodia, microvilli, and ridges, with rounded bleb-like projections being the most common and rapidly achieved form of storage. We demonstrate that, similar to rounded cells in 2D culture, rounded cells in 3D collagen contain large amounts of CSE and use it to cover developing protrusions. Upon retraction of a protrusion, the CSE this produces is stored over the cell body similar to the CSE produced by cell rounding. We present high-resolution imaging of F-actin and microtubules (MTs) for different cell lines in a 3D environment and demonstrate the correlated changes between CSE and protrusion dynamics. To coordinate CSE storage and release with protrusion formation and motility, we expect cells to have specific mechanisms for regulating CSE, and we hypothesize that MTs play a substantial role in this mechanism by reducing cell surface dynamics and stabilizing CSE. We also suggest that different effects of MT depolymerization on cell motility, such as inhibiting mesenchymal motility and enhancing amoeboid, can be explained by this role of MTs in CSE regulation.
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Affiliation(s)
- Maryna Kapustina
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
| | - Donna Li
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - James Zhu
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Brittany Wall
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Violetta Weinreb
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Richard E Cheney
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Sadhu RK, Hernandez-Padilla C, Eisenbach YE, Penič S, Zhang L, Vishwasrao HD, Behkam B, Konstantopoulos K, Shroff H, Iglič A, Peles E, Nain AS, Gov NS. Experimental and theoretical model for the origin of coiling of cellular protrusions around fibers. Nat Commun 2023; 14:5612. [PMID: 37699891 PMCID: PMC10497540 DOI: 10.1038/s41467-023-41273-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 08/29/2023] [Indexed: 09/14/2023] Open
Abstract
Protrusions at the leading-edge of a cell play an important role in sensing the extracellular cues during cellular spreading and motility. Recent studies provided indications that these protrusions wrap (coil) around the extracellular fibers. However, the physics of this coiling process, and the mechanisms that drive it, are not well understood. We present a combined theoretical and experimental study of the coiling of cellular protrusions on fibers of different geometry. Our theoretical model describes membrane protrusions that are produced by curved membrane proteins that recruit the protrusive forces of actin polymerization, and identifies the role of bending and adhesion energies in orienting the leading-edges of the protrusions along the azimuthal (coiling) direction. Our model predicts that the cell's leading-edge coils on fibers with circular cross-section (above some critical radius), but the coiling ceases for flattened fibers of highly elliptical cross-section. These predictions are verified by 3D visualization and quantitation of coiling on suspended fibers using Dual-View light-sheet microscopy (diSPIM). Overall, we provide a theoretical framework, supported by experiments, which explains the physical origin of the coiling phenomenon.
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Affiliation(s)
- Raj Kumar Sadhu
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 7610001, Israel.
- Institut Curie, PSL Research University, CNRS, UMR 168, Paris, France.
| | | | - Yael Eshed Eisenbach
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Samo Penič
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Lixia Zhang
- Advanced Imaging and Microscopy Resource, National Institutes of Health, Bethesda, MD, USA
| | - Harshad D Vishwasrao
- Advanced Imaging and Microscopy Resource, National Institutes of Health, Bethesda, MD, USA
| | - Bahareh Behkam
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA, 24061, USA
| | | | - Hari Shroff
- Advanced Imaging and Microscopy Resource, National Institutes of Health, Bethesda, MD, USA
- Laboratory of High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, USA
| | - Aleš Iglič
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Elior Peles
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Amrinder S Nain
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA, 24061, USA.
| | - Nir S Gov
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 7610001, Israel.
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Francis EA, Heinrich V. Integrative experimental/computational approach establishes active cellular protrusion as the primary driving force of phagocytic spreading by immune cells. PLoS Comput Biol 2022; 18:e1009937. [PMID: 36026476 PMCID: PMC9455874 DOI: 10.1371/journal.pcbi.1009937] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 09/08/2022] [Accepted: 07/27/2022] [Indexed: 12/02/2022] Open
Abstract
The dynamic interplay between cell adhesion and protrusion is a critical determinant of many forms of cell motility. When modeling cell spreading on adhesive surfaces, traditional mathematical treatments often consider passive cell adhesion as the primary, if not exclusive, mechanistic driving force of this cellular motion. To better assess the contribution of active cytoskeletal protrusion to immune-cell spreading during phagocytosis, we here develop a computational framework that allows us to optionally investigate both purely adhesive spreading (“Brownian zipper hypothesis”) as well as protrusion-dominated spreading (“protrusive zipper hypothesis”). We model the cell as an axisymmetric body of highly viscous fluid surrounded by a cortex with uniform surface tension and incorporate as potential driving forces of cell spreading an attractive stress due to receptor-ligand binding and an outward normal stress representing cytoskeletal protrusion, both acting on the cell boundary. We leverage various model predictions against the results of a directly related experimental companion study of human neutrophil phagocytic spreading on substrates coated with different densities of antibodies. We find that the concept of adhesion-driven spreading is incompatible with experimental results such as the independence of the cell-spreading speed on the density of immobilized antibodies. In contrast, the protrusive zipper model agrees well with experimental findings and, when adapted to simulate cell spreading on discrete adhesion sites, it also reproduces the observed positive correlation between antibody density and maximum cell-substrate contact area. Together, our integrative experimental/computational approach shows that phagocytic spreading is driven by cellular protrusion, and that the extent of spreading is limited by the density of adhesion sites. To accomplish many routine biological tasks, cells must rapidly spread over different types of surfaces. Here, we examine the biophysical underpinnings of immune cell spreading during phagocytosis, the process by which white blood cells such as neutrophils engulf pathogens or other foreign objects. Our computational framework models the case in which a human neutrophil spreads over a flat surface coated with antibodies, which we also test experimentally in a companion paper. Our primary purpose is to assess whether phagocytic spreading is actively driven by protrusive forces exerted by the cell, or passively by adhesive forces acting between receptors in the cell membrane and antibodies on the surface. By directly comparing our model predictions to experimental results, we demonstrate that phagocytic spreading is primarily driven by protrusion, but the extent of spreading is still limited by the availability of binding sites. Our findings improve the fundamental understanding of phagocytosis and may also pave the way for future investigations of the balance between adhesion and protrusion in other forms of cell spreading, such as wound healing or cancer cell migration.
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Affiliation(s)
- Emmet A. Francis
- Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America
- * E-mail: (EAF); (VH)
| | - Volkmar Heinrich
- Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America
- * E-mail: (EAF); (VH)
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7
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Jaffe E, Niswander L. Loss of Grhl3 is correlated with altered cellular protrusions in the non-neural ectoderm during neural tube closure. Dev Dyn 2021; 250:732-744. [PMID: 33378081 DOI: 10.1002/dvdy.292] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 12/21/2020] [Accepted: 12/21/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The transcription factor Grainyhead-like 3 (GRHL3) has multiple roles in a variety of tissues during development including epithelial patterning and actin cytoskeletal regulation. During neural tube closure (NTC) in the mouse embryo, GRHL3 is expressed and functions in the non-neural ectoderm (NNE). Two important functions of GRHL3 are regulating the actin cytoskeleton during NTC and regulating the boundary between the NNE and neural ectoderm. However, an open question that remains is whether these functions explain the caudally restricted neural tube defect (NTD) of spina bifida observed in Grhl3 mutants. RESULTS Using scanning electron microscopy and immunofluorescence based imaging on Grhl3 mutants and wildtype controls, we show that GRHL3 is dispensable for NNE identity or epithelial maintenance in the caudal NNE but is needed for regulation of cellular protrusions during NTC. Grhl3 mutants have decreased lamellipodia relative to wildtype embryos during caudal NTC, first observed at the onset of delays when lamellipodia become prominent in wildtype embryos. At the axial level of NTD, half of the mutants show increased and disorganized filopodia and half lack cellular protrusions. CONCLUSION These data suggest that altered cellular protrusions during NTC contribute to the etiology of NTD in Grhl3 mutants.
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Affiliation(s)
- Eric Jaffe
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Lee Niswander
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
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8
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Maddess T, Coy D, Herrington JC, Carle CF, Sabeti F, Barbosa MS. Learning complex texture discrimination. J Opt Soc Am A Opt Image Sci Vis 2021; 38:449-455. [PMID: 33690477 DOI: 10.1364/josaa.413065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 01/10/2021] [Indexed: 06/12/2023]
Abstract
Higher-order spatial correlations contribute strongly to visual structure and salience, and are common in the natural environment. One method for studying this structure has been through the use of highly controlled texture patterns whose obvious structure is defined entirely by third- and higher-order correlations. Here we examine the effects that longer-term training has on discrimination of 17 such texture types. Training took place in 14 sessions over 42 days. Discrimination performance increased at different rates for different textures. The time required to complete a visit reduced by 25.4% (p=0.0004). Factor analysis was applied to data from the learning and experienced phases of the experiment. This indicated that the gain in speed was accompanied by an increase in the number of mechanisms contributing to discrimination. Learning was not affected by sleep quality but was affected by extreme tiredness (p<0.01). The improved discrimination and speed were retained for 2.5 months. Overall, the effects were consistent with perceptual learning. The observed learning is likely related to the adaptation of innate mechanisms that underlie our ability to identify nonredundant, visually salient structure in natural images. It may involve cortical V2 and appears to involve increased strength, speed, and breadth of connections within our internal representation of this complex perceptual space.
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9
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Miao Y, Bhattacharya S, Banerjee T, Abubaker-Sharif B, Long Y, Inoue T, Iglesias PA, Devreotes PN. Wave patterns organize cellular protrusions and control cortical dynamics. Mol Syst Biol 2019; 15:e8585. [PMID: 30858181 PMCID: PMC6413885 DOI: 10.15252/msb.20188585] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 01/31/2019] [Accepted: 02/04/2019] [Indexed: 02/06/2023] Open
Abstract
Cellular protrusions are typically considered as distinct structures associated with specific regulators. However, we found that these regulators coordinately localize as propagating cortical waves, suggesting a common underlying mechanism. These molecular events fell into two excitable networks, the signal transduction network STEN and the cytoskeletal network CEN with different wave substructures. Computational studies using a coupled-network model reproduced these features and showed that the morphology and kinetics of the waves depended on strengths of feedback loops. Chemically induced dimerization at multiple nodes produced distinct, coordinated alterations in patterns of other network components. Taken together, these studies indicate: STEN positive feedback is mediated by mutual inhibition between Ras/Rap and PIP2, while negative feedback depends on delayed PKB activation; PKBs link STEN to CEN; CEN includes positive feedback between Rac and F-actin, and exerts fast positive and slow negative feedbacks to STEN The alterations produced protrusions resembling filopodia, ruffles, pseudopodia, or lamellipodia, suggesting that these structures arise from a common regulatory mechanism and that the overall state of the STEN-CEN system determines cellular morphology.
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Affiliation(s)
- Yuchuan Miao
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Sayak Bhattacharya
- Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Tatsat Banerjee
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Bedri Abubaker-Sharif
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Yu Long
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Takanari Inoue
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Pablo A Iglesias
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Peter N Devreotes
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
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10
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Abstract
Transport of molecular motors along protein filaments in a half-closed geometry is a common feature of biologically relevant processes in cellular protrusions. Using a lattice-gas model we study how the interplay between active and diffusive transport and mass conservation leads to localized domain walls and tip localization of the motors. We identify a mechanism for task sharing between the active motors (maintaining a gradient) and the diffusive motion (transport to the tip), which ensures that energy consumption is low and motor exchange mostly happens at the tip. These features are attributed to strong nearest-neighbor correlations that lead to a strong reduction of active currents, which we calculate analytically using an exact moment identity, and might prove useful for the understanding of correlations and active transport also in more elaborate systems.
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Affiliation(s)
- Isabella R Graf
- Arnold-Sommerfeld-Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, D-80333 Munich, Germany
| | - Erwin Frey
- Arnold-Sommerfeld-Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, D-80333 Munich, Germany
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Pinkoviezky I, Gov NS. Exclusion and Hierarchy of Time Scales Lead to Spatial Segregation of Molecular Motors in Cellular Protrusions. Phys Rev Lett 2017; 118:018102. [PMID: 28106430 DOI: 10.1103/physrevlett.118.018102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Indexed: 06/06/2023]
Abstract
Molecular motors that carry cargo along biopolymer filaments within cells play a crucial role in the functioning of the cell. In particular, these motors are essential for the formation and maintenance of the cellular protrusions that play key roles in motility and specific functionalities, such as the stereocilia in hair cells. Typically, there are several species of motors, carrying different cargos, that share the same track. Furthermore, it was observed that in the mature stereocilia, the different motors occupy well-segregated bands as a function of distance from the tip. We use a totally asymmetric exclusion process model with two- and three-motor species, to study the conditions that give rise to such spatial patterns. We find that the well-segregated bands appear for motors with a strong hierarchy of attachment or detachment rates. This is a striking example of pattern formation in nonequilibrium, low-dimensional systems.
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Affiliation(s)
- I Pinkoviezky
- Department of Chemical Physics, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel
| | - N S Gov
- Department of Chemical Physics, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel
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12
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Carey SP, Goldblatt ZE, Martin KE, Romero B, Williams RM, Reinhart-King CA. Local extracellular matrix alignment directs cellular protrusion dynamics and migration through Rac1 and FAK. Integr Biol (Camb) 2016; 8:821-35. [PMID: 27384462 PMCID: PMC4980151 DOI: 10.1039/c6ib00030d] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Cell migration within 3D interstitial microenvironments is sensitive to extracellular matrix (ECM) properties, but the mechanisms that regulate migration guidance by 3D matrix features remain unclear. To examine the mechanisms underlying the cell migration response to aligned ECM, which is prevalent at the tumor-stroma interface, we utilized time-lapse microscopy to compare the behavior of MDA-MB-231 breast adenocarcinoma cells within randomly organized and well-aligned 3D collagen ECM. We developed a novel experimental system in which cellular morphodynamics during initial 3D cell spreading served as a reductionist model for the complex process of matrix-directed 3D cell migration. Using this approach, we found that ECM alignment induced spatial anisotropy of cells' matrix probing by promoting protrusion frequency, persistence, and lengthening along the alignment axis and suppressing protrusion dynamics orthogonal to alignment. Preference for on-axis behaviors was dependent upon FAK and Rac1 signaling and translated across length and time scales such that cells within aligned ECM exhibited accelerated elongation, front-rear polarization, and migration relative to cells in random ECM. Together, these findings indicate that adhesive and protrusive signaling allow cells to respond to coordinated physical cues in the ECM, promoting migration efficiency and cell migration guidance by 3D matrix structure.
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Affiliation(s)
- Shawn P Carey
- Department of Biomedical Engineering, Cornell University, 302 Weill Hall, 526 Campus Rd, Ithaca, New York 14853, USA.
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Beckham Y, Vasquez RJ, Stricker J, Sayegh K, Campillo C, Gardel ML. Arp2/3 inhibition induces amoeboid-like protrusions in MCF10A epithelial cells by reduced cytoskeletal-membrane coupling and focal adhesion assembly. PLoS One 2014; 9:e100943. [PMID: 24967897 PMCID: PMC4072770 DOI: 10.1371/journal.pone.0100943] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 06/02/2014] [Indexed: 11/18/2022] Open
Abstract
Here we demonstrate that Arp2/3 regulates a transition between mesenchymal and amoeboid protrusions in MCF10A epithelial cells. Using genetic and pharmacological means, we first show Arp2/3 inhibition impairs directed cell migration. Arp2/3 inhibition results in a dramatically impaired cell adhesion, causing deficient cell attachment and spreading to ECM as well as an 8-fold decrease in nascent adhesion assembly at the leading edge. While Arp2/3 does not play a significant role in myosin-dependent adhesion growth, mature focal adhesions undergo large scale movements against the ECM suggesting reduced coupling to the ECM. Cell edge protrusions occur at similar rates when Arp2/3 is inhibited but their morphology is dramatically altered. Persistent lamellipodia are abrogated and we observe a markedly increased incidence of blebbing and unstable pseuodopods. Micropipette-aspiration assays indicate that Arp2/3-inhibited cells have a weak coupling between the cell cortex and the plasma membrane, and suggest a potential mechanism for increased pseudopod and bleb formation. Pseudopods are not sensitive to reduced in formin or myosin II activity. Collectively, these results indicate that Arp2/3 is not necessary for rapid protrusion of the cell edge but plays a crucial role in assembling focal adhesions required for its stabilization.
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Affiliation(s)
- Yvonne Beckham
- Institute for Biophysical Dynamics, University of Chicago Medical Center, Chicago, Illinois, United States of America
| | - Robert J. Vasquez
- Section of Hematology, Oncology and Stem Cell Transplantation, Department of Pediatrics, University of Chicago Medical Center, Chicago, Illinois, United States of America
| | - Jonathan Stricker
- James Franck Institute, University of Chicago, Chicago, Illinois, United States of America
- Department of Physics, University of Chicago, Chicago, Illinois, United States of America
| | - Kareem Sayegh
- James Franck Institute, University of Chicago, Chicago, Illinois, United States of America
- Department of Physics, University of Chicago, Chicago, Illinois, United States of America
| | - Clement Campillo
- Laboratoire Physico-Chimie, Institut Curie, Centre de Recherche, Paris, France
- Laboratoire Analyse et Modélisation pour la Biologie et l’ Environnement, Université d’Evry Val d’Essonne, Evry, France
| | - Margaret L. Gardel
- Institute for Biophysical Dynamics, University of Chicago Medical Center, Chicago, Illinois, United States of America
- James Franck Institute, University of Chicago, Chicago, Illinois, United States of America
- Department of Physics, University of Chicago, Chicago, Illinois, United States of America
- * E-mail:
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14
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Ziemann A, Hess S, Bhuwania R, Linder S, Kloppenburg P, Noegel AA, Clemen CS. CRN2 enhances the invasiveness of glioblastoma cells. Neuro Oncol 2013; 15:548-61. [PMID: 23410663 PMCID: PMC3635520 DOI: 10.1093/neuonc/nos388] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 12/17/2012] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Movement of tumor cells involves dynamic remodeling of the actin cytoskeleton, which is regulated by actin binding proteins, such as CRN2 (synonyms: coronin 1C, coronin 3). In vitro, CRN2 participates in secretion, matrix degradation, protrusion formation, and cell migration. Furthermore, expression of CRN2 correlates with the malignant phenotype of human diffuse gliomas. CRN2's effects on actin polymerization and F-actin bundling are abolished by protein kinase 2 (CK2) dependent phosphorylation at serine 463. METHODS We generated human U373 glioblastoma cell lines with knock-down of CRN2 or over-expression of CRN2 variants and studied their behavior in vitro and ex vivo in organotypic brain slice cultures. RESULTS CRN2 over-expression and expression of the S463A phospho-resistant CRN2 variant increase proliferation, matrix degradation, and invasion but decrease adhesion and formation of invadopodia-like extensions in vitro. Knock-down of CRN2 and expression of S463D phospho-mimetic CRN2 generally have opposite effects. Analysis of invadopodia-like cell extensions shows a diffuse relocalization of F-actin in CRN2 knockdown cells, whereas expression of S463A and S463D mutant CRN2 causes enrichments of F-actin structures at the center and rime zone, respectively. Fluorescence recovery after photobleaching studies of CRN2 and F-actin in lamellipodia show that both CRN2 variants decrease the turnover of actin filaments. Glioblastoma cells over-expressing wild-type or S463A CRN2, which were transplanted onto brain slices, characteristically developed into tumors with an invasive phenotype. CONCLUSIONS Overall, our data indicate that CRN2 participates in cancer progression via modulation of the actin cytoskeleton.
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Affiliation(s)
- Anja Ziemann
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty (A.Z., A.A.N., C.S.C.), Institute of Zoology (S.H., P.K.), Center for Molecular Medicine Cologne (S.H., P.K., A.A.N.), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne (S.H., P.K., A.A.N.); and Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (R.B., S.L.)
| | - Simon Hess
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty (A.Z., A.A.N., C.S.C.), Institute of Zoology (S.H., P.K.), Center for Molecular Medicine Cologne (S.H., P.K., A.A.N.), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne (S.H., P.K., A.A.N.); and Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (R.B., S.L.)
| | - Ridhirama Bhuwania
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty (A.Z., A.A.N., C.S.C.), Institute of Zoology (S.H., P.K.), Center for Molecular Medicine Cologne (S.H., P.K., A.A.N.), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne (S.H., P.K., A.A.N.); and Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (R.B., S.L.)
| | - Stefan Linder
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty (A.Z., A.A.N., C.S.C.), Institute of Zoology (S.H., P.K.), Center for Molecular Medicine Cologne (S.H., P.K., A.A.N.), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne (S.H., P.K., A.A.N.); and Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (R.B., S.L.)
| | - Peter Kloppenburg
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty (A.Z., A.A.N., C.S.C.), Institute of Zoology (S.H., P.K.), Center for Molecular Medicine Cologne (S.H., P.K., A.A.N.), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne (S.H., P.K., A.A.N.); and Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (R.B., S.L.)
| | - Angelika A. Noegel
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty (A.Z., A.A.N., C.S.C.), Institute of Zoology (S.H., P.K.), Center for Molecular Medicine Cologne (S.H., P.K., A.A.N.), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne (S.H., P.K., A.A.N.); and Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (R.B., S.L.)
| | - Christoph S. Clemen
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty (A.Z., A.A.N., C.S.C.), Institute of Zoology (S.H., P.K.), Center for Molecular Medicine Cologne (S.H., P.K., A.A.N.), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne (S.H., P.K., A.A.N.); and Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (R.B., S.L.)
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15
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Meddens MBM, Rieger B, Figdor CG, Cambi A, van den Dries K. Automated podosome identification and characterization in fluorescence microscopy images. Microsc Microanal 2013; 19:180-189. [PMID: 23347434 DOI: 10.1017/s1431927612014018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Podosomes are cellular adhesion structures involved in matrix degradation and invasion that comprise an actin core and a ring of cytoskeletal adaptor proteins. They are most often identified by staining with phalloidin, which binds F-actin and therefore visualizes the core. However, not only podosomes, but also many other cytoskeletal structures contain actin, which makes podosome segmentation by automated image processing difficult. Here, we have developed a quantitative image analysis algorithm that is optimized to identify podosome cores within a typical sample stained with phalloidin. By sequential local and global thresholding, our analysis identifies up to 76% of podosome cores excluding other F-actin-based structures. Based on the overlap in podosome identifications and quantification of podosome numbers, our algorithm performs equally well compared to three experts. Using our algorithm we show effects of actin polymerization and myosin II inhibition on the actin intensity in both podosome core and associated actin network. Furthermore, by expanding the core segmentations, we reveal a previously unappreciated differential distribution of cytoskeletal adaptor proteins within the podosome ring. These applications illustrate that our algorithm is a valuable tool for rapid and accurate large-scale analysis of podosomes to increase our understanding of these characteristic adhesion structures.
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Affiliation(s)
- Marjolein B M Meddens
- Department of Tumor Immunology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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16
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Eaton CJ, Cabrera IE, Servin JA, Wright SJ, Cox MP, Borkovich KA. The guanine nucleotide exchange factor RIC8 regulates conidial germination through Gα proteins in Neurospora crassa. PLoS One 2012; 7:e48026. [PMID: 23118921 PMCID: PMC3485287 DOI: 10.1371/journal.pone.0048026] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2012] [Accepted: 09/25/2012] [Indexed: 11/20/2022] Open
Abstract
Heterotrimeric G protein signaling is essential for normal hyphal growth in the filamentous fungus Neurospora crassa. We have previously demonstrated that the non-receptor guanine nucleotide exchange factor RIC8 acts upstream of the Gα proteins GNA-1 and GNA-3 to regulate hyphal extension. Here we demonstrate that regulation of hyphal extension results at least in part, from an important role in control of asexual spore (conidia) germination. Loss of GNA-3 leads to a drastic reduction in conidial germination, which is exacerbated in the absence of GNA-1. Mutation of RIC8 leads to a reduction in germination similar to that in the Δgna-1, Δgna-3 double mutant, suggesting that RIC8 regulates conidial germination through both GNA-1 and GNA-3. Support for a more significant role for GNA-3 is indicated by the observation that expression of a GTPase-deficient, constitutively active gna-3 allele in the Δric8 mutant leads to a significant increase in conidial germination. Localization of the three Gα proteins during conidial germination was probed through analysis of cells expressing fluorescently tagged proteins. Functional TagRFP fusions of each of the three Gα subunits were constructed through insertion of TagRFP in a conserved loop region of the Gα subunits. The results demonstrated that GNA-1 localizes to the plasma membrane and vacuoles, and also to septa throughout conidial germination. GNA-2 and GNA-3 localize to both the plasma membrane and vacuoles during early germination, but are then found in intracellular vacuoles later during hyphal outgrowth.
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Affiliation(s)
- Carla J. Eaton
- Department of Plant Pathology and Microbiology and Institute for Integrative Genome Biology, University of California Riverside, Riverside, California, United States of America
| | - Ilva E. Cabrera
- Department of Plant Pathology and Microbiology and Institute for Integrative Genome Biology, University of California Riverside, Riverside, California, United States of America
| | - Jacqueline A. Servin
- Department of Plant Pathology and Microbiology and Institute for Integrative Genome Biology, University of California Riverside, Riverside, California, United States of America
| | - Sara J. Wright
- Department of Plant Pathology and Microbiology and Institute for Integrative Genome Biology, University of California Riverside, Riverside, California, United States of America
| | - Murray P. Cox
- Institute of Molecular BioSciences, Massey University, The Bio-Protection Research Centre and The Allan Wilson Centre for Molecular Ecology and Evolution, Palmerston North, New Zealand
| | - Katherine A. Borkovich
- Department of Plant Pathology and Microbiology and Institute for Integrative Genome Biology, University of California Riverside, Riverside, California, United States of America
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17
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de Rezende FF, Martins Lima A, Niland S, Wittig I, Heide H, Schröder K, Eble JA. Integrin α7β1 is a redox-regulated target of hydrogen peroxide in vascular smooth muscle cell adhesion. Free Radic Biol Med 2012; 53:521-31. [PMID: 22659335 DOI: 10.1016/j.freeradbiomed.2012.05.032] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 05/16/2012] [Accepted: 05/22/2012] [Indexed: 01/15/2023]
Abstract
Upon adhesion to laminin-111, aortic smooth muscle cells initially form membrane protrusions with an average diameter of 2.9μm. We identified these protrusions also as subcellular areas of increased redox potential and protein oxidation by detecting cysteine sulfenic acid groups with dimedone. Hence, we termed these areas oxidative hot spots. They are spatially and temporally transient during an early stage of adhesion and depend on the activity of the H(2)O(2)-generating NADPH oxidase 4. Presumably located on cellular protrusions, integrin α7β1 mediates adhesion and migration of vascular smooth muscle cells to laminins of their surrounding basement membrane. Using protein chemistry and mass spectrometry, two specific oxidation sites within the integrin α7 subunit were identified: one located in its genu region and another within its calf 2 domain. Upon H(2)O(2) treatment, two cysteine residues are oxidized thereby unlocking a disulfide bridge. The genu region is a hinge, around which the integrin domains pivot between a bent/inactive and an upright/active conformation. Also, cysteine oxidation within the calf 2 domain permits conformational changes related to integrin activation. H(2)O(2) treatment of α7β1 integrin in concentrations of up to 100μM increases integrin binding activity to laminin-111, suggesting a physiological redox regulation of α7β1 integrin.
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Affiliation(s)
- Flávia Figueiredo de Rezende
- Excellence Cluster Cardio-Pulmonary System, Vascular Matrix Biology, Center for Molecular Medicine, Frankfurt University Hospital, Frankfurt am Main, Germany
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18
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Abstract
The Deleted in liver cancer one (Dlc1) tumor suppressor gene encodes a RhoGTPase activating protein (RhoGAP). The Dlc1 gene has multiple transcriptional isoforms and we have previously established a mouse strain containing a gene trap (gt) insertion, which specifically reduces the expression of the 6.1 kb isoform (isoform 2). This gene trapped allele when homozygous results in embryonic lethality and the heterozygous gene trapped mice do not show an increased incidence of cancers, suggesting that cooperating oncogenic changes may be required for transformation. In the present work, we have studied the in vivo cooperation between oncogenic K-Ras2 and Dlc1 genes in tumourigenesis. We have observed an increase in invasive thymic cancers, including both thymomas and lymphomas, resulting in significantly shortened life spans in mice heterozygous for the gt Dlc1 allele and an inducible LSL-K-Ras2G12D allele compared with the LSL-K-Ras2G12D only mice. The heterozygous mice showed a high degree of metastasis in the lung. We have found tumour specific selective hypermethylation of the Dlc1 isoform 2 promoter and reduction of the corresponding protein expression in thymic lymphoma (TL) and thymic epithelial carcinoma (TEC) derived from the thymic tumours. The Dlc1 deficient thymic lymphoma cell lines exhibited increased trans-endothelial cell migration. TEC cell lines also exhibited increased stress fiber formation and Rho activity. Introduction of the three Dlc1 isoforms tagged with GFP into these cells resulted in different morphological changes. These results suggest that loss of expression of only isoform 2 may be sufficient for the development of thymic tumors and metastasis.
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MESH Headings
- Animals
- Base Sequence
- Cell Shape
- Cell Surface Extensions
- Chromosome Mapping
- CpG Islands
- Cyclin-Dependent Kinase Inhibitor p21/metabolism
- DNA Methylation
- GTPase-Activating Proteins/genetics
- GTPase-Activating Proteins/metabolism
- GTPase-Activating Proteins/physiology
- Gene Expression Regulation, Neoplastic
- Lung Neoplasms/genetics
- Lung Neoplasms/metabolism
- Lung Neoplasms/secondary
- Lymphoma, T-Cell/genetics
- Lymphoma, T-Cell/metabolism
- Lymphoma, T-Cell/pathology
- Mice
- Mice, Transgenic
- Molecular Sequence Data
- Mutation, Missense
- Neoplasms, Experimental/genetics
- Neoplasms, Experimental/metabolism
- Neoplasms, Experimental/pathology
- Promoter Regions, Genetic
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Protein Isoforms/physiology
- Proto-Oncogene Proteins p21(ras)/genetics
- Stress Fibers/metabolism
- Thymoma/genetics
- Thymoma/metabolism
- Thymoma/secondary
- Thymus Neoplasms/genetics
- Thymus Neoplasms/metabolism
- Thymus Neoplasms/pathology
- Transendothelial and Transepithelial Migration
- Tumor Cells, Cultured
- Tumor Suppressor Proteins/genetics
- Tumor Suppressor Proteins/metabolism
- Tumor Suppressor Proteins/physiology
- rho GTP-Binding Proteins/metabolism
- rhoA GTP-Binding Protein
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Affiliation(s)
- Mohammad Golam Sabbir
- Manitoba Institute of Cell Biology, CancerCare Manitoba, Winnipeg, Manitoba, Canada
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Heather Prieditis
- Manitoba Institute of Cell Biology, CancerCare Manitoba, Winnipeg, Manitoba, Canada
| | - Esther Ravinsky
- Department of Pathology, Health Sciences Centre, Winnipeg, Manitoba, Canada
| | - Michael R. A. Mowat
- Manitoba Institute of Cell Biology, CancerCare Manitoba, Winnipeg, Manitoba, Canada
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
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19
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Kong YK, Zhang Y, Lin MH, Xi XD. [A single E726Q mutation in the membrane proximal α-helix of integrin β3 subunit induces membrane blebbing by disrupting the membrane-actin cortex interaction]. Zhongguo Shi Yan Xue Ye Xue Za Zhi 2011; 19:1450-1455. [PMID: 22169302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The membrane proximal α helix of integrin β subunit cytoplasmic tails plays an important functional role by interacting with various intracellular proteins, namely talin, α-actinin or skelemin. This study was designed to investigate the functional role of 5 highly conserved charged amino acids (R(724), K(725), E(726), E(731), E(733)) within this α helix by site-directed mutagenesis. The result showed that CHO cells expressing the αIIbβ3E726Q mutant had the most prominent phenotype and characterized by defective cell spreading on immobilized fibrinogen. In addition, this E726Q mutation induced membrane blebbing in cells adherent on fibrinogen, and this blebbing could be inhibited by the myosin light chain ATPase inhibitor blebbistatin. It is concluded that the membrane proximal α-helix of integrin β3 subunit is important in linking the phospholipid membrane to the submembraneous actin cortex.
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Affiliation(s)
- Yong-Kui Kong
- Shanghai Institute of Hematology, Shanghai Jiaotong University School of Medicine, Shanghai, China
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20
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Guo M, Cao L, Lu P, Liu Y, Xu X. Anticorrosion and cytocompatibility behavior of MAO/PLLA modified magnesium alloy WE42. J Mater Sci Mater Med 2011; 22:1735-40. [PMID: 21630093 DOI: 10.1007/s10856-011-4354-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2010] [Accepted: 05/16/2011] [Indexed: 05/23/2023]
Abstract
Recently, biodegradable magnesium alloys have been introduced in the field of cardiovascular stents to avoid the specific drawbacks of permanent metallic implants. However, the major obstacle of the clinical use of magnesium-based materials is their rapid corrosion rate. In this paper, a composite micro-arc oxidation/poly-L: -lactic acid (MAO/PLLA) coating was fabricated on the surface of the magnesium alloy WE42 to improve its corrosion resistance and the cytocompatibility of the modified materials was also investigated for safety aim. In our study, the morphology of materials was analyzed by Scanning electron microscopy. Potentiodynamic polarization was used to evaluate the corrosion behavior of the samples and corrosion weight loss was used to demonstrate their degradation rate. Furthermore, we applied cytotoxicity test in testing the cytocompatibility of the modified samples. The results showed that the PLLA coating effectively sealed the microcracks and micropores on the surface of the MAO coating by physical interlocking to interfere the corrosion ions. The corrosion rate was decreased and the cyototoxicity test showed that the MAO/PLLA composite coating WE42 had good cytocompatibility.
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Affiliation(s)
- Meiqing Guo
- School of Materials Science and Engineering, Tianjin University, Tianjin 300072, People's Republic of China
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21
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Luo T. [Simple extraction of nucleus pulposus through intervertebral approach for the treatment of great protrusion of lumbar intervertebral disk]. Zhongguo Gu Shang 2010; 23:795-796. [PMID: 21137301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Affiliation(s)
- Tao Luo
- The Beijing Hospital of TCM Affiliated to Capital Medical University, Beijing 100010, China.
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22
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Teodorof C, Bae JI, Kim SM, Oh HJ, Kang YS, Choi J, Chun JS, Song WK. SPIN90-IRSp53 complex participates in Rac-induced membrane ruffling. Exp Cell Res 2009; 315:2410-9. [PMID: 19460367 DOI: 10.1016/j.yexcr.2009.05.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 05/11/2009] [Accepted: 05/14/2009] [Indexed: 11/17/2022]
Abstract
SPIN90 is a key regulator of actin cytoskeletal organization. Using the BioGRID(beta) database (General Repository for Interaction Datasets), we identified IRSp53 as a binding partner of SPIN90, and confirmed the in vivo formation of a SPIN90-IRSp53 complex mediated through direct association of the proline-rich domain (PRD) of SPIN90 with the SH3 domain of IRSp53. SPIN90 and IRSp53 positively cooperated to mediate Rac activation, and co-expression of SPIN90 and IRSp53 in COS-7 cells led to the complex formation of SPIN90-IRSp53 in the leading edge of cells. PDGF treatment induced strong colocalization of SPIN90 and IRSp53 at membrane protrusions. Within such PDGF-induced protrusions, knockdown of SPIN90 protein using siRNA significantly reduced lamellipodia-like protrusions as well as localization of IRSp53 at those sites. Finally, competitive inhibition of SPIN90-IRSp53 binding by SPIN90 PRD dramatically reduced ruffle formation, further suggesting that SPIN90 plays a key role in the formation of the membrane protrusions associated with cell motility.
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Affiliation(s)
- Carmen Teodorof
- Bio Imaging Research Center, Cell Dynamics Research Center, Department of Life Science, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, South Korea
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23
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Abstract
Cancer cells migrating within a 3D microenvironment are able to adopt either a mesenchymal or amoeboid mode of migration. Amoeboid migration is characterised by membrane blebbing that is dependent on the Rho effectors, ROCK1/2. We identify LIMK2 as the preferred substrate for ROCK1 but find that LIMK2 did not induce membrane blebbing, suggesting that a LIMK2 pathway is not involved in amoeboid-mode migration. In support of this hypothesis, novel FRET data demonstrate a direct interaction between ROCK1 and LIMK2 in polarised but not blebbing cells. Our results point to a specific role for the ROCK1:LIMK2 pathway in mesenchymal-mode migration.
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Affiliation(s)
- Kerry F. Shea
- Randall Division of Cell & Molecular Biophysics, King's College London, London, United Kingdom
- AstraZeneca, Cancer and Infection Research Area, Macclesfield, United Kingdom
| | - Claire M. Wells
- Randall Division of Cell & Molecular Biophysics, King's College London, London, United Kingdom
- Division of Cancer Studies, Kings College London, London, United Kingdom
| | - Andrew P. Garner
- AstraZeneca, Cancer and Infection Research Area, Macclesfield, United Kingdom
| | - Gareth E. Jones
- Randall Division of Cell & Molecular Biophysics, King's College London, London, United Kingdom
- * E-mail:
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24
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Abstract
Research on mesoporous materials for biomedical purposes has experienced an outstanding increase during recent years. Since 2001, when MCM-41 was first proposed as drug-delivery system, silica-based materials, such as SBA-15 or MCM-48, and some metal-organic frameworks have been discussed as drug carriers and controlled-release systems. Mesoporous materials are intended for both systemic-delivery systems and implantable local-delivery devices. The latter application provides very promising possibilities in the field of bone-tissue repair because of the excellent behavior of these materials as bioceramics. This Minireview deals with the advances in this field by the control of the textural parameters, surface functionalization, and the synthesis of sophisticated stimuli-response systems.
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Affiliation(s)
- María Vallet-Regí
- Departamento de Química Inorgánica y Bioinorgánica, Facultad de Farmacia, Universidad Complutense de Madrid, 28040 Madrid, Spain.
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25
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Sarkar SK, Andoy NM, Benítez JJ, Chen PR, Kong JS, He C, Chen P. Engineered holliday junctions as single-molecule reporters for protein-DNA interactions with application to a MerR-family regulator. J Am Chem Soc 2007; 129:12461-7. [PMID: 17880214 PMCID: PMC2528078 DOI: 10.1021/ja072485y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Protein-DNA interactions are essential for gene maintenance, replication, and expression. Characterizing how proteins interact with and change the structure of DNA is crucial in elucidating the mechanisms of protein function. Here, we present a novel and generalizable method of using engineered DNA Holliday junctions (HJs) that contain specific protein-recognition sequences to report protein-DNA interactions in single-molecule FRET measurements, utilizing the intrinsic structural dynamics of HJs. Because the effects of protein binding are converted to the changes in the structure and dynamics of HJs, protein-DNA interactions that involve small structural changes of DNA can be studied. We apply this method to investigate how the MerR-family regulator PbrR691 interacts with DNA for transcriptional regulation. Both apo- and holo-PbrR691 bind the stacked conformers of the engineered HJ, change their structures, constrain their conformational distributions, alter the kinetics, and shift the equilibrium of their structural dynamics. The information obtained maps the potential energy surfaces of HJ before and after PbrR691 binding and reveals the protein actions that force DNA structural changes for transcriptional regulation. The ability of PbrR691 to bind both HJ conformers and still allow HJ structural dynamics also informs about its conformational flexibility that may have significance for its regulatory function. This method of using engineered HJs offers quantification of the changes both in structure and in dynamics of DNA upon protein binding and thus provides a new tool to elucidate the correlation of structure, dynamics, and function of DNA-binding proteins.
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Affiliation(s)
- Susanta K. Sarkar
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853
| | - Nesha May Andoy
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853
| | - Jaime J. Benítez
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853
| | - Peng R. Chen
- Department of Chemistry, University of Chicago, 929 E 57th Street, Chicago, IL 60637
| | - Jason S. Kong
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853
| | - Chuan He
- Department of Chemistry, University of Chicago, 929 E 57th Street, Chicago, IL 60637
| | - Peng Chen
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853
- To whom correspondence should be addressed
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Benninger Y, Thurnherr T, Pereira JA, Krause S, Wu X, Chrostek-Grashoff A, Herzog D, Nave KA, Franklin RJM, Meijer D, Brakebusch C, Suter U, Relvas JB. Essential and distinct roles for cdc42 and rac1 in the regulation of Schwann cell biology during peripheral nervous system development. ACTA ACUST UNITED AC 2007; 177:1051-61. [PMID: 17576798 PMCID: PMC2064365 DOI: 10.1083/jcb.200610108] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
During peripheral nervous system (PNS) myelination, Schwann cells must interpret extracellular cues to sense their environment and regulate their intrinsic developmental program accordingly. The pathways and mechanisms involved in this process are only partially understood. We use tissue-specific conditional gene targeting to show that members of the Rho GTPases, cdc42 and rac1, have different and essential roles in axon sorting by Schwann cells. Our results indicate that although cdc42 is required for normal Schwann cell proliferation, rac1 regulates Schwann cell process extension and stabilization, allowing efficient radial sorting of axon bundles.
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Affiliation(s)
- Yves Benninger
- Institute of Cell Biology, Department of Biology, Eidgenössische Technische Hochschule Zurich, CH-8093 Zurich, Switzerland
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27
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Abstract
During the development of the peripheral nervous system, Schwann cells select individual axons from a nerve bundle and establish a one-to-one relationship through a process termed “radial sorting”. Recent findings identify the Rho family GTPase Rac1 as the downstream effector molecule responsible for process extension and lamellipodia formation in Schwann cells, allowing for proper radial sorting and myelination. These findings begin to shed light on our understanding of the distinct and yet essential molecular mechanisms involved in developmental processes preceding myelination.
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Affiliation(s)
- Jonah R Chan
- Zilkha Neurogenetic Institute, Department of Biochemistry and Molecular Biology, Keck School of Medicine at the University of Southern California, Los Angeles, CA 90033, USA.
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28
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Nodari A, Zambroni D, Quattrini A, Court FA, D'Urso A, Recchia A, Tybulewicz VLJ, Wrabetz L, Feltri ML. Beta1 integrin activates Rac1 in Schwann cells to generate radial lamellae during axonal sorting and myelination. ACTA ACUST UNITED AC 2007; 177:1063-75. [PMID: 17576799 PMCID: PMC2064366 DOI: 10.1083/jcb.200610014] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Myelin is a multispiraled extension of glial membrane that surrounds axons. How glia extend a surface many-fold larger than their body is poorly understood. Schwann cells are peripheral glia and insert radial cytoplasmic extensions into bundles of axons to sort, ensheath, and myelinate them. Laminins and β1 integrins are required for axonal sorting, but the downstream signals are largely unknown. We show that Schwann cells devoid of β1 integrin migrate to and elongate on axons but cannot extend radial lamellae of cytoplasm, similar to cells with low Rac1 activation. Accordingly, active Rac1 is decreased in β1 integrin–null nerves, inhibiting Rac1 activity decreases radial lamellae in Schwann cells, and ablating Rac1 in Schwann cells of transgenic mice delays axonal sorting and impairs myelination. Finally, expressing active Rac1 in β1 integrin–null nerves improves sorting. Thus, increased activation of Rac1 by β1 integrins allows Schwann cells to switch from migration/elongation to the extension of radial membranes required for axonal sorting and myelination.
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Affiliation(s)
- Alessandro Nodari
- Department of Biological and Technological Research, San Raffaele Scientific Institute, 20132 Milan, Italy
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29
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Abstract
The conformations of vesicles deformed by microtubules are studied within the framework of the curvature energy. The phenomenon in which the destruction of a microtubule is followed by the formation of peristaltic shapes on a protrusion created by the microtubule is investigated. The influence of the spontaneous curvature on the conformations of vesicles is examined, and the results are compared to existing experiments. The elastic properties of a vesicle deformed by the microtubule are studied.
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Affiliation(s)
- W T Góźdź
- Institute of Physical Chemistry Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
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31
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Collett J, Crawford A, Hatton PV, Geoghegan M, Rimmer S. Thermally responsive polymeric hydrogel brushes: synthesis, physical properties and use for the culture of chondrocytes. J R Soc Interface 2007; 4:117-26. [PMID: 17254980 PMCID: PMC2358963 DOI: 10.1098/rsif.2006.0158] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Hydrogel brushes are materials composed of a water-swollen network, which contains polymer chains that are grafted with another polymer. Using a thermally responsive polymer, poly(N-isopropyl acrylamide) (polyNIPAM), as the graft component we are able to maintain the critical solution temperature (Tcrit), independent of the overall composition of the material, at approximately 32 degrees C. The change in swelling at Tcrit is a function of the amount of polyNIPAM in the system. However, there is a much smaller change in the surface contact angles at Tcrit. PolyNIPAM-based materials have generated considerable interest, as 'smart' substrates for the culture of cells and here, we show the utility of hydrogel brushes in cell culture. Chondrocytes attached to the hydrogel brushes and yielded viable cell cultures. Moreover, the chondrocytes could be released from the hydrogel brushes without the use of proteases by reducing the temperature of the cultures to below Tcrit to induce a change in the conformation of the polyNIPAM chain at Tcrit. The importance of the crosslink hydrogel component is illustrated by significant changes in cell attachment/cell viability as the crosslink density is changed.
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Affiliation(s)
- John Collett
- Department of Chemistry, University of SheffieldSheffield, South Yorkshire S3 7HF, UK
- Centre for Biomaterials and Tissue Engineering, University of SheffieldSheffield, South Yorkshire S3 7HQ, UK
| | - Aileen Crawford
- Centre for Biomaterials and Tissue Engineering, University of SheffieldSheffield, South Yorkshire S3 7HQ, UK
- School of Clinical Dentistry, University of SheffieldSheffield, South Yorkshire S10 2TA, UK
| | - Paul V Hatton
- Centre for Biomaterials and Tissue Engineering, University of SheffieldSheffield, South Yorkshire S3 7HQ, UK
- School of Clinical Dentistry, University of SheffieldSheffield, South Yorkshire S10 2TA, UK
| | - Mark Geoghegan
- Department of Physics and Astronomy, University of SheffieldSheffield, South Yorkshire S3 7RH, UK
| | - Stephen Rimmer
- Department of Chemistry, University of SheffieldSheffield, South Yorkshire S3 7HF, UK
- Centre for Biomaterials and Tissue Engineering, University of SheffieldSheffield, South Yorkshire S3 7HQ, UK
- Author for correspondence ()
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32
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Areekijseree M, Vejaratpimol R. In vivo and in vitro study of porcine oviductal epithelial cells, cumulus oocyte complexes and granulosa cells: A scanning electron microscopy and inverted microscopy study. Micron 2006; 37:707-16. [PMID: 16716597 DOI: 10.1016/j.micron.2006.03.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Revised: 03/07/2006] [Accepted: 03/07/2006] [Indexed: 11/26/2022]
Abstract
The morphology and structure of porcine oviductal epithelial cells (POEC), cumulus-oocyte complexes (COCs) and granulosa cells (GC) were investigated in vivo and in vitro conditions using scanning electron microscopy (SEM) and inverted microscopy. The POEC contained columnar ciliated cells and spherical shaped non-ciliated cells. Both non- and ciliated cells appeared either in groups or distributing among each other. However, the isolation of cells was observed after culture for 48 h. A total of 921 oocytes from 20 ovaries was isolated resulting in an average of 46 oocytes per ovary. They were round in shape, surrounded by zona pellucida with layers of cumulus cells ranging between 89.16 and 144.68 microm in size. As for COCs, they were classified into 4 types; intact-, multi-, partial-cumulus cell layers and completely denuded oocyte. Interestingly, changes in morphology of COCs with intact and multi-cumulus cell layers were observed in the in vitro study. The GCs in the follicular fluid were also round in shape and found as clusters. After culturing in in vitro for 48 h, no change in morphology was observed. The GC appeared in smaller clusters or were present as single cells and their sizes ranged from 6 to 8 microm. The results obtained from this study allow us to have a better understanding of the morphology and nature of cells under both in vivo and in vitro conditions. This information is also important for the study of their secretions and biochemical compositions, which is of great importance to the use of cells as feeder cells in in vitro fertilization in current studies.
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Affiliation(s)
- Mayuva Areekijseree
- Department of Biology, Faculty of Science, Silpakorn University, Nakorn Pathom 73000, Thailand.
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Sebaihia M, Preston A, Maskell DJ, Kuzmiak H, Connell TD, King ND, Orndorff PE, Miyamoto DM, Thomson NR, Harris D, Goble A, Lord A, Murphy L, Quail MA, Rutter S, Squares R, Squares S, Woodward J, Parkhill J, Temple LM. Comparison of the genome sequence of the poultry pathogen Bordetella avium with those of B. bronchiseptica, B. pertussis, and B. parapertussis reveals extensive diversity in surface structures associated with host interaction. J Bacteriol 2006; 188:6002-15. [PMID: 16885469 PMCID: PMC1540077 DOI: 10.1128/jb.01927-05] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bordetella avium is a pathogen of poultry and is phylogenetically distinct from Bordetella bronchiseptica, Bordetella pertussis, and Bordetella parapertussis, which are other species in the Bordetella genus that infect mammals. In order to understand the evolutionary relatedness of Bordetella species and further the understanding of pathogenesis, we obtained the complete genome sequence of B. avium strain 197N, a pathogenic strain that has been extensively studied. With 3,732,255 base pairs of DNA and 3,417 predicted coding sequences, it has the smallest genome and gene complement of the sequenced bordetellae. In this study, the presence or absence of previously reported virulence factors from B. avium was confirmed, and the genetic bases for growth characteristics were elucidated. Over 1,100 genes present in B. avium but not in B. bronchiseptica were identified, and most were predicted to encode surface or secreted proteins that are likely to define an organism adapted to the avian rather than the mammalian respiratory tracts. These include genes coding for the synthesis of a polysaccharide capsule, hemagglutinins, a type I secretion system adjacent to two very large genes for secreted proteins, and unique genes for both lipopolysaccharide and fimbrial biogenesis. Three apparently complete prophages are also present. The BvgAS virulence regulatory system appears to have polymorphisms at a poly(C) tract that is involved in phase variation in other bordetellae. A number of putative iron-regulated outer membrane proteins were predicted from the sequence, and this regulation was confirmed experimentally for five of these.
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Affiliation(s)
- Mohammed Sebaihia
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, United Kingdom
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34
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Abstract
Junctional adhesion molecule-A (JAM-A) is an adhesive protein expressed in endothelial cells, epithelial cells, platelets, and some leukocytes. JAM-A localizes to the tight junctions between contacting endothelial and epithelial cells, where it contributes to cell-cell adhesion and to the control of paracellular permeability. JAM-A also regulates cell motility, even though the quantitative biophysical features have not been characterized. In this study, we evaluated the role of JAM-A in the regulation of cell motility using JAM-A-expressing and JAM-A-deficient murine endothelial cells. We report that, in the absence of shear stress, JAM-A absence increases cell motility by increasing directional persistence but not cell speed. In addition, in the presence of shear stress, JAM-A absence increases protrusion extension in the direction of flow and increased downstream cellular displacement (while, conversely, decreasing upstream displacement). All these effects of JAM-A absence are mitigated by the microtubule-stabilizing compound taxol. A motility- and microtubule-related function, integrin-mediated adhesiveness, was only slightly reduced in JAM-A-deficient cells compared with JAM-A-expressing cells. However, overexpression of JAM-A in the JAM-A-deficient cells increased integrin adhesiveness to the same levels as those observed in taxol-treated JAM-A-deficient cells. Taken together, these data indicate that JAM-A regulates cell motility by cooperating with microtubule-stabilizing pathways.
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Affiliation(s)
- Hayden Huang
- Cardiovascular Division, Brigham and Women's Hospital, Cambridge, Massachusetts 02139, USA.
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35
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Seballos L, Zhang JZ, Sutphen R. Surface-enhanced Raman scattering detection of lysophosphatidic acid. Anal Bioanal Chem 2005; 383:763-7. [PMID: 16261318 PMCID: PMC3303217 DOI: 10.1007/s00216-005-0097-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 08/28/2005] [Accepted: 08/31/2005] [Indexed: 10/25/2022]
Abstract
Surface-enhanced Raman scattering using silver nanoparticles was applied to detect various forms of lysophosphatidic acid (LPA) to examine its potential application as an alternative to current detection methods of LPA as biomarkers of ovarian cancer. Enhancement of the Raman modes of the molecule, especially those related to the acyl chain within the 800-1300 cm(-1) region, was observed. In particular, the C-C vibration mode of the gauche-bonded chain around 1100 cm(-1) was enhanced to allow the discrimination of two similar LPA molecules. Given the molecular selectivity of this technique, the detection of LPA using SERS may eliminate the need for partial purification of samples prior to analysis in cancer screening.
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Affiliation(s)
- Leo Seballos
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Jin Z. Zhang
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA, Tel.: +1-831-4593776, Fax: +1-831-4592935
| | - Rebecca Sutphen
- Department of Interdisciplinary Oncology, College of Medicine and H. Lee Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, FL 33612, USA
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36
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Abstract
We show here that methylene-blue supravital staining of specimens from normal human mammary gland reveals (selectively) interstitial (stromal) cells, with 2-3 long (20-80 microm), thin, moniliform processes. Such cells appear c-kit/CD117 positive, either by immunohistochemistry (IHC) or immunofluorescence (IF). Since these features (affinity for methylene blue, c-kit positivity, and characteristic processes) define archetypal interstitial cells of Cajal (ICC) in light microscopy, our results suggest the existence of Cajal-like cells in the interstitium of human normal mammary gland.
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Affiliation(s)
- L M Popescu
- Department of Cellular and Molecular Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, 050474, Romania.
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37
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Abstract
Anillins are conserved proteins that are important for stabilizing and remodeling the actin cytoskeleton. Anillins have been implicated in cytokinesis in several systems and in cellularization of the syncytial Drosophila embryo. Here, we examine the functions of three C. elegans proteins with homology to anillin (ANI-1, ANI-2 and ANI-3). We show that ANI-1 and ANI-2 contribute to embryonic viability by performing distinct functions in the early embryo and gonad, respectively. By contrast, ANI-3 appears to be dispensable for embryonic development. ANI-1 is essential for cortical ruffling and pseudocleavage, contractile events that occur in embryos prior to mitosis. ANI-1 is also required for the highly asymmetric cytokinetic events that extrude the two polar bodies during oocyte meiosis, but is dispensable for cytokinesis following mitotic chromosome segregation. During both meiosis and mitosis, ANI-1 targets the septins, but not myosin II, to the contractile ring and does not require either for its own targeting. In contrast to ANI-1, ANI-2 functions during oogenesis to maintain the structure of the rachis, the central core of cytoplasm that connects the developing oocytes in the syncytial gonad. In ANI-2-depleted worms, oocytes disconnect prematurely from the defective rachis, generating embryos of varying sizes. Our results highlight specialization of divergent anillin family proteins in the C. elegans life cycle and reveal conserved roles for this protein family in organizing syncytial structures and cortical contractility.
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Affiliation(s)
- Amy Shaub Maddox
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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38
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Abstract
Our brain serves as a center for cognitive function and neurons within the brain relay and store information about our surroundings and experiences. Modulation of this complex neuronal circuitry allows us to process that information and respond appropriately. Proper development of neurons is therefore vital to the mental health of an individual, and perturbations in their signaling or morphology are likely to result in cognitive impairment. The development of a neuron requires a series of steps that begins with migration from its birth place and initiation of process outgrowth, and ultimately leads to differentiation and the formation of connections that allow it to communicate with appropriate targets. Over the past several years, it has become clear that the Rho family of GTPases and related molecules play an important role in various aspects of neuronal development, including neurite outgrowth and differentiation, axon pathfinding, and dendritic spine formation and maintenance. Given the importance of these molecules in these processes, it is therefore not surprising that mutations in genes encoding a number of regulators and effectors of the Rho GTPases have been associated with human neurological diseases. This review will focus on the role of the Rho GTPases and their associated signaling molecules throughout neuronal development and discuss how perturbations in Rho GTPase signaling may lead to cognitive disorders.
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Affiliation(s)
- Eve-Ellen Govek
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
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Rosenberger G, Gal A, Kutsche K. αPIX Associates with Calpain 4, the Small Subunit of Calpain, and Has a Dual Role in Integrin-mediated Cell Spreading. J Biol Chem 2005; 280:6879-89. [PMID: 15611136 DOI: 10.1074/jbc.m412119200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Binding of integrins to the extracellular matrix results in actin cytoskeletal rearrangements, e.g. during cell spreading, by regulating the activity of Rho GTP-ases. We have shown previously that alphaPIX (Cool-2 or ARHGEF6), a Rac1/Cdc42-specific guanine nucleotide exchange factor (GEF), binds to beta-parvin/affixin and colocalizes with integrin-linked kinase in actively spreading cells, suggesting that alphaPIX is involved in integrin-induced signaling leading to activation of Rac1/Cdc42. Here we report calpain 4, the small subunit of the proteases mu-calpain and m-calpain, as a novel binding partner of alphaPIX. This association was identified by the CytoTrap system and confirmed by coimmunoprecipitation and glutathione S-transferase pull-down assays. The alphaPIX triple domain SH3-DH-PH was found to be required for calpain 4 binding. During integrin-dependent spreading of CHO-K1 cells, alphaPIX colocalized with mu- and m-calpain, integrin-linked kinase, and beta1 integrin in early integrin-containing clusters. Overexpression of alphaPIX wild type but not the GEF-deficient mutant (L386R/L387S) resulted in enhanced formation of characteristic cellular protrusions during cell spreading, suggesting that alphaPIX GEF activity is necessary for this specific actin cytoskeletal reorganization. The calpain inhibitors calpeptin and calpain inhibitor IV significantly inhibited integrin-dependent cell spreading. However, concomitant overexpression of alphaPIX wild type or the L386R/L387S mutant restored cell spreading. Together, these data suggest that alphaPIX is a component of early integrin clusters and plays a dual role in integrin-dependent cell spreading. Whereas alphaPIX GEF activity contributes to enhanced formation of cellular protrusions, the GEF-independent association with calpain 4 leads to induction of a yet unknown signaling cascade resulting in cell spreading.
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Affiliation(s)
- Georg Rosenberger
- Institut für Humangenetik, Universitätsklinikum Hamburg-Eppendorf, D-22529 Hamburg, Germany
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40
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Liu Y, Yang YW, Chen Y. Thio[2-(benzoylamino)ethylamino]-β-CD fragment modified gold nanoparticles as recycling extractors for [60]fullerene. Chem Commun (Camb) 2005:4208-10. [PMID: 16100605 DOI: 10.1039/b507650a] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Gold particles are modified with surface-attached bis(beta-cyclodextrin)s bearing S-S bridges to give water-soluble cyclodextrin-modified gold nanoparticles, which are successfully used as recycling extractors for [60]fullerene.
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Affiliation(s)
- Yu Liu
- Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, P. R. China.
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41
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Abstract
In the present study we characterize a novel RhoGAP protein (RC-GAP72) that interacts with actin stress fibers, focal adhesions, and cell-cell adherens junctions via its 185-amino acid C-terminal region. Overexpression of RC-GAP72 in fibroblasts induces cell rounding with partial or complete disruption of actin stress fibers and formation of membrane ruffles, lamellipodia, and filopodia. RC-GAP72 mutant truncated downstream of the GTPase-activating protein (GAP) domain retains the ability to stimulate membrane protrusions but fails to affect stress fiber integrity or induce cell retraction. A mutant protein consisting of the C terminus of RC-GAP72 and lacking the GAP domain does not exert any visible effect on cellular morphology. Inactivation of the GAP domain by a point mutation does not abolish the effect of RC-GAP72 on actin stress fibers but moderates its capability to induce membrane protrusions. Our data imply that the cytoskeletal localization of RC-GAP72 and its interaction with GTPases are essential for its effect on the integrity of actin stress fibers, whereas the induction of lamellipodia and filopodia depends on the activity of the GAP domain irrespective of binding to the actin cytoskeleton. We propose that RC-GAP72 affects cellular morphology by targeting activated Cdc42 and Rac1 GTPases to specific subcellular sites, triggering local morphological changes. The overall physiological functions of RC-GAP72 are presently unknown, yet our data suggest that RC-GAP72 plays a role in regulating cell morphology and cytoskeletal organization.
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Affiliation(s)
- Irena Lavelin
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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42
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Affiliation(s)
- Carrie Phillips
- Indiana University School of Medicine, Indianapolis, IN, USA.
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Yasuda K, Inoue S, Tabata Y. Influence of Culture Method on the Proliferation and Osteogenic Differentiation of Human Adipo-stromal Cells in Nonwoven Fabrics. ACTA ACUST UNITED AC 2004; 10:1587-96. [PMID: 15588418 DOI: 10.1089/ten.2004.10.1587] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The initial attachment, proliferation, and osteogenic differentiation of stromal cells from human fat tissue were investigated in three-dimensional nonwoven fabrics prepared from polyethylene terephthalate (PET) fiber with different diameters. The largest number of cells initially attached was observed in the nonwoven fabrics prepared from PET fiber with a diameter of 22.0 microm, irrespective of fabric porosity. The number of cells attached was larger and the cells were distributed more homogeneously in the fabrics by the agitated seeding method than by the static seeding method. The culture method depended on the time profile of cell proliferation. Cell proliferation improved in the following order: stirred (spinner flask) culture method > agitated culture method > static culture method. In addition, cells proliferated homogeneously in fabrics by the stirred culture method. When evaluated as a measurement of cell osteogenic differentiation, the activity of alkaline phosphatase (ALP) was not influenced by the diameter of fabrics. The static culture method tended to enable cells to enhance ALP activity, in contrast with the stirred and agitated culture methods. It is concluded that fabric fiber diameter and culture method greatly affected the proliferation and differentiation of cells in nonwoven fabrics.
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Affiliation(s)
- Kaori Yasuda
- Field of Tissue Engineering, Department of Biomaterials, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
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44
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Abstract
A partially biodegradable and thermosensitive hybrid hydrogel network (DAN series) based on dextran-allylisocyanate (Dex-AI) and poly(N-isopropylacrylamide) (PNIPAAm) was synthesized via UV photocrosslinking. These hybrid hydrogels were characterized in terms of their chemical structure, thermal, mechanical, morphological and temperature-induced swelling properties. The effect of the composition ratio of Dex-AI to PNIPAAm on such properties were examined. The differential scanning calorimetry data show that this Dex-AI/PNIPAAm hybrid network has an increased lower critical solution temperature (LCST) and glass transition temperature (Tg) with an increase in the Dex-AI content. The interior morphology of these hybrid hydrogels revealed a decreased porous microstructure with an increase in the Dex-AI content in the hybrid network. Furthermore, if the Dex-AI composition became too high, a distinctive network structure with two different microporous structures appeared. The mechanical properties of these hybrid hydrogels also increased with an increase in the Dex-AI content. The temperature dependence of the swelling ratio, the deswelling kinetics as well as the reswelling kinetics was also characterized by gravimetric method. When comparing with a normal PNIPAAm hydrogel, these Dex-AI/PNIPAAm hybrid networks, due to the presence of Dex-AI moiety, also show improved temperature-induced intelligent properties, such as the faster and controllable response dynamics, which may find promising applications in a wide variety of fields, such as biomedical and bioengineering fields.
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Affiliation(s)
- Xian-Zheng Zhang
- Department of Textiles and Apparel and Biomedical Engineering Program, Cornell University, Ithaca, New York 14853-4401, USA
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Zhang Y, Chen K, Tu Y, Wu C. Distinct roles of two structurally closely related focal adhesion proteins, alpha-parvins and beta-parvins, in regulation of cell morphology and survival. J Biol Chem 2004; 279:41695-705. [PMID: 15284246 DOI: 10.1074/jbc.m401563200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Proteins at cell-extracellular matrix adhesions (e.g. focal adhesions) are crucially involved in regulation of cell morphology and survival. We show here that CH-ILKBP/actopaxin/alpha-parvin and affixin/beta-parvin (abbreviated as alpha- and beta-parvin, respectively), two structurally closely related integrin-linked kinase (ILK)-binding focal adhesion proteins, are co-expressed in human cells. Depletion of alpha-parvin dramatically increased the level of beta-parvin, suggesting that beta-parvin is negatively regulated by alpha-parvin in human cells. Loss of PINCH-1 or ILK, to which alpha- and beta-parvin bind, significantly reduced the activation of Rac, a key signaling event that controls lamellipodium formation and cell spreading. We were surprised to find that loss of alpha-parvin, but not that of beta-parvin, markedly stimulated Rac activation and enhanced lamellipodium formation. Overexpression of beta-parvin, however, was insufficient for stimulation of Rac activation or lamellipodium formation, although it was sufficient for promotion of apoptosis, another important cellular process that is regulated by PINCH-1, ILK, and alpha-parvin. In addition, we show that the interactions of ILK with alpha- and beta-parvin are mutually exclusive. Overexpression of beta-parvin or its CH(2) fragment, but not a CH(2) deletion mutant, inhibited the ILK-alpha-parvin complex formation. Finally, we provide evidence suggesting that inhibition of the ILK-alpha-parvin complex is sufficient, although not necessary, for promotion of apoptosis. These results identify Rac as a downstream target of PINCH-1, ILK, and parvin. Furthermore, they demonstrate that alpha- and beta-parvins play distinct roles in mammalian cells and suggest that the formation of the ILK-alpha-parvin complex is crucial for protection of cells from apoptosis.
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Affiliation(s)
- Yongjun Zhang
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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González P, Serra J, Liste S, Chiussi S, León B, Pérez-Amor M, Martínez-Fernández J, de Arellano-López AR, Varela-Feria FM. New biomorphic SiC ceramics coated with bioactive glass for biomedical applications. Biomaterials 2004; 24:4827-32. [PMID: 14530079 DOI: 10.1016/s0142-9612(03)00405-8] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A new generation of light, tough and high-strength material for medical implants for bone substitutions with a good biological response is presented. The innovative product that fulfills all these requirements is based on biomorphic silicon carbide ceramics coated with a bioactive glass layer. The combination of the excellent mechanical properties and low density of the biomorphic SiC ceramics, used as a base material for implants, with the osteoconducting properties of the bioactive glass materials opens new possibilities for the development of alternative dental and orthopedic implants with enhanced mechanical and biochemical properties that ensures optimum fixation to living tissue. Biomorphic SiC is fabricated by molten-Si infiltration of carbon templates obtained by controlled pyrolysis of wood. Through this process, the microstructure of the final SiC product mimics that of the starting wood, which has been perfected by natural evolution. The basic features of such microstructure are its porosity (ranging from 30% to 70%) and its anisotropy, which resembles the cellular microstructure and the mechanical characteristics of the bone. The SiC ceramics have been successfully coated with a uniform and adherent bioactive glass film by pulsed laser ablation using an excimer ArF laser. The excellent coverage of the SiC rough surface without film spallation or detachment is demonstrated. In order to assess the coating bioactivity, in vitro tests by soaking the samples in simulated body fluid have been carried out. After 72 h, the formation of a dense apatite layer has been observed even in interconnecting pores by SEM and energy dispersive X-ray spectroscopy analysis demonstrating the bioactive response of this product.
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Affiliation(s)
- P González
- Departamento de Física Aplicada, Universidade de Vigo, Lagoas-Marcosende 9, 36280 Vigo, Spain.
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Calle Y, Jones GE, Jagger C, Fuller K, Blundell MP, Chow J, Chambers T, Thrasher AJ. WASp deficiency in mice results in failure to form osteoclast sealing zones and defects in bone resorption. Blood 2004; 103:3552-61. [PMID: 14726392 DOI: 10.1182/blood-2003-04-1259] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
AbstractNo defects related to deficiency of the Wiskott-Aldrich Syndrome protein (WASp) have been described in osteoclasts. Here we show that there are significant morphologic and functional abnormalities. WASp-null cells spread over a much larger surface area and are highly polykaryotic. In their migratory phase, normal cells assemble clusters of podosomes behind their leading edges, whereas during the bone resorptive phase multiple podosomes are densely aggregated in well-defined actin rings forming the sealing zone. In comparison, WASp-null osteoclasts in either phase are markedly depleted of podosomes. On bone surfaces, this results in a failure to form actin rings at sealing zones. Complementation of WASp-null osteoclasts with an enhanced green fluorescent protein (eGFP)-WASp fusion protein restores normal cytoarchitecture. These structural disturbances translate into abnormal patterns of bone resorption both in vitro on bone slices and in vivo. Although physiologic steady-state levels of bone resorption are maintained, a major impairment is observed when WASp-null animals are exposed to a resorptive challenge. Our results provide clear evidence that WASp is a critical component of podosomes in osteoclasts and indicate a nonredundant role for WASp in the dynamic organization of these actin structures during bone resorption. (Blood. 2004;103:3552-3561)
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Affiliation(s)
- Yolanda Calle
- The Randall Centre for Molecular Mechanisms of Cell Function, New Hunt's House, King's College London, Guy's Campus, London, United Kingdom.
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Rother K, Preissner R, Goede A, Frömmel C. Inhomogeneous molecular density: reference packing densities and distribution of cavities within proteins. Bioinformatics 2004; 19:2112-21. [PMID: 14594717 DOI: 10.1093/bioinformatics/btg292] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
MOTIVATION There is no consensus in the literature about how the deepest portions of protein structures are packed. Using an improved Voronoi procedure, we calculate reference packing densities for different regions in the protein interior. Furthermore, we want to clarify where cavities are located. RESULTS Sets of reference packing densities are provided for regions in proteins that differ in their distance to the surface and to internal cavities, supplementing previous data. Packing in the protein interior is tight but generally inhomogeneous. There are about 4.4 cavities per 100 amino acids in protein structures, they occur in all regions, most frequently in a depth of 2.5-3.6 A underneath the Connolly surface. However, the deepest protein regions have a lower mean packing density than circumjacent regions, because more contacts to cavities occur in the core. AVAILABILITY/SUPPLEMENTARY INFORMATION Calculation software and detailed packing data are available on request.
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Affiliation(s)
- Kristian Rother
- Berlin Center of Genome Based Bioinformatics (BCB), Humboldt University, Institute of Biochemistry at the Charite, Monbijoustr. 2, 10117 Berlin, Germany
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Sumoza-Toledo A, Santos-Argumedo L. The spreading of B lymphocytes induced by CD44 cross-linking requires actin, tubulin, and vimentin rearrangements. J Leukoc Biol 2003; 75:233-9. [PMID: 14634057 DOI: 10.1189/jlb.0803403] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
CD44 is a polymorphic family of adhesion molecules widely distributed on cells and tissues. CD44 is up-regulated on activated lymphocytes, and it can function as a receptor, mediating rolling and migration. Although it has been demonstrated that anti-CD44 antibodies bound to tissue-culture plates induce multidirectional emission of retractile dendrites ("spreading") in activated murine B lymphocytes, the involvement of cytoskeleton elements in this phenomenon is largely unknown. In this work, it is shown that the generation of dendrites induced by CD44 cross-linking in activated B cells depends on actin, microtubules, and vimentin reorganization. Immunofluorescence analysis showed that dendrite formation began with actin polymerization, and its extension was favored by microtubules and intermediate filaments of vimentin oriented to the polymerized actin. Pretreatment of activated B lymphocytes with cytochalasin E inhibited the dendrites formation; moreover, when cells were treated with this drug at different time points during the dendrite formation process, the stability of the dendrites was affected. In contrast, although the treatment with colchicine and nocodazole (tubulin polymerization inhibitors) inhibited the dendrites formation, it did not inhibit the initial phase of actin polymerization. According to these results, B cell spreading and dendrite formation induced by anti-CD44 antibodies require coordinated rearrangements of actin, microtubules, and vimentin, being the actin cytoskeleton, the most important element that confers stability and drives the morphological changes during B cell spreading, conceivably preparing B lymphocytes for locomotion.
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Affiliation(s)
- Adriana Sumoza-Toledo
- Department of Molecular Biomedicine, Centro de Investigación y Estudios Avanzados, IPN, Mexico
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Mironov AA, Mironov AA, Beznoussenko GV, Trucco A, Lupetti P, Smith JD, Geerts WJC, Koster AJ, Burger KNJ, Martone ME, Deerinck TJ, Ellisman MH, Luini A. ER-to-Golgi carriers arise through direct en bloc protrusion and multistage maturation of specialized ER exit domains. Dev Cell 2003; 5:583-94. [PMID: 14536060 DOI: 10.1016/s1534-5807(03)00294-6] [Citation(s) in RCA: 196] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Protein transport between the ER and the Golgi in mammalian cells occurs via large pleiomorphic carriers, and most current models suggest that these are formed by the fusion of small ER-derived COPII vesicles. We have examined the dynamics and structural features of these carriers during and after their formation from the ER by correlative video/light electron microscopy and tomography. We found that saccular carriers containing either the large supramolecular cargo procollagen or the small diffusible cargo protein VSVG arise through cargo concentration and direct en bloc protrusion of specialized ER domains in the vicinity of COPII-coated exit sites. This formation process is COPII dependent but does not involve budding and fusion of COPII-dependent vesicles. Fully protruded saccules then move centripetally, evolving into one of two types of carriers (with distinct kinetic and structural features). These findings provide an alternative framework for analysis of ER-to-Golgi traffic.
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Affiliation(s)
- Alexander A Mironov
- Department of Cell Biology and Oncology, Istituto di Ricerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro, (Chieti), Italy
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