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Jia Y, Wu SL, Isenberg JS, Dai S, Sipes JM, Field L, Zeng B, Bandle RW, Ridnour LA, Wink DA, Ramchandran R, Karger BL, Roberts DD. Thiolutin inhibits endothelial cell adhesion by perturbing Hsp27 interactions with components of the actin and intermediate filament cytoskeleton. Cell Stress Chaperones 2010; 15:165-81. [PMID: 19579057 PMCID: PMC2866983 DOI: 10.1007/s12192-009-0130-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 06/12/2009] [Accepted: 06/17/2009] [Indexed: 10/20/2022] Open
Abstract
Thiolutin is a dithiole synthesized by Streptomyces sp. that inhibits endothelial cell adhesion and tumor growth. We show here that thiolutin potently inhibits developmental angiogenesis in zebrafish and vascular outgrowth from tissue explants in 3D cultures. Thiolutin is a potent and selective inhibitor of endothelial cell adhesion accompanied by rapid induction of HSPB1 (Hsp27) phosphorylation. The inhibitory effects of thiolutin on endothelial cell adhesion are transient, potentially due to a compensatory increase in Hsp27 protein levels. Accordingly, heat shock induction of Hsp27 limits the anti-adhesive activity of thiolutin. Thiolutin treatment results in loss of actin stress fibers, increased cortical actin as cells retract, and decreased cellular F-actin. Mass spectrometric analysis of Hsp27 binding partners following immunoaffinity purification identified several regulatory components of the actin cytoskeleton that associate with Hsp27 in a thiolutin-sensitive manner including several components of the Arp2/3 complex. Among these, ArpC1a is a direct binding partner of Hsp27. Thiolutin treatment induces peripheral localization of phosphorylated Hsp27 and Arp2/3. Hsp27 also associates with the intermediate filament components vimentin and nestin. Thiolutin treatment specifically ablates Hsp27 interaction with nestin and collapses nestin filaments. These results provide new mechanistic insights into regulation of cell adhesion and cytoskeletal dynamics by Hsp27.
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Affiliation(s)
- Yifeng Jia
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - Shiaw-Lin Wu
- Barnett Institute, Northeastern University, Boston, MA 02115 USA
| | - Jeff S. Isenberg
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
- Hemostasis and Vascular Biology Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261 USA
| | - Shujia Dai
- Barnett Institute, Northeastern University, Boston, MA 02115 USA
| | - John M. Sipes
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - Lyndsay Field
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - Bixi Zeng
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - Russell W. Bandle
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - Lisa A. Ridnour
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - David A. Wink
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - Ramani Ramchandran
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
- Department of Pediatrics, Children’s Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226 USA
| | - Barry L. Karger
- Barnett Institute, Northeastern University, Boston, MA 02115 USA
| | - David D. Roberts
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
- NIH, Building 10 Room 2A33, 10 Center Dr MSC1500, Bethesda, MD 20892-1500 USA
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153
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Ezratty EJ, Bertaux C, Marcantonio EE, Gundersen GG. Clathrin mediates integrin endocytosis for focal adhesion disassembly in migrating cells. ACTA ACUST UNITED AC 2010; 187:733-47. [PMID: 19951918 PMCID: PMC2806590 DOI: 10.1083/jcb.200904054] [Citation(s) in RCA: 261] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Focal adhesion disassembly is regulated by microtubules (MTs) through an unknown mechanism that involves dynamin. To test whether endocytosis may be involved, we interfered with the function of clathrin or its adaptors autosomal recessive hypercholesteremia (ARH) and Dab2 (Disabled-2) and found that both treatments prevented MT-induced focal adhesion disassembly. Surface labeling experiments showed that integrin was endocytosed in an extracellular matrix-, clathrin-, and ARH- and Dab2-dependent manner before entering Rab5 endosomes. Clathrin colocalized with a subset of focal adhesions in an ARH- and Dab2-dependent fashion. Direct imaging showed that clathrin rapidly accumulated on focal adhesions during MT-stimulated disassembly and departed from focal adhesions with integrin upon their disassembly. In migrating cells, depletion of clathrin or Dab2 and ARH inhibited focal adhesion disassembly and decreased the rate of migration. These results show that focal adhesion disassembly occurs through a targeted mechanism involving MTs, clathrin, and specific clathrin adaptors and that direct endocytosis of integrins from focal adhesions mediates their disassembly in migrating cells.
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Affiliation(s)
- Ellen J Ezratty
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
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154
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Self-Assembled Monolayers as Dynamic Model Substrates for Cell Biology. BIOACTIVE SURFACES 2010. [DOI: 10.1007/12_2010_87] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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155
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Scharnagl N, Lee S, Hiebl B, Sisson A, Lendlein A. Design principles for polymers as substratum for adherent cells. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/c0jm00997k] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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156
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Akkouch A, Shi G, Zhang Z, Rouabhia M. Bioactivating electrically conducting polypyrrole with fibronectin and bovine serum albumin. J Biomed Mater Res A 2010; 92:221-31. [DOI: 10.1002/jbm.a.32357] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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157
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Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV), the most recently identified member of the herpesvirus family, infects a variety of target cells in vitro and in vivo. This minireview surveys current information on the early events of KSHV infection, including virus-receptor interactions, involved envelope glycoproteins, mode of entry, intracellular trafficking, and initial viral and host gene expression programs. We describe data supporting the hypothesis that KSHV manipulates preexisting host cell signaling pathways to allow successful infection. The various signaling events triggered by infection, and their potential roles in the different stages of infection and disease pathogenesis, are summarized.
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158
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Hehlgans S, Lange I, Eke I, Cordes N. 3D cell cultures of human head and neck squamous cell carcinoma cells are radiosensitized by the focal adhesion kinase inhibitor TAE226. Radiother Oncol 2009; 92:371-8. [PMID: 19729215 DOI: 10.1016/j.radonc.2009.08.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 07/01/2009] [Accepted: 08/07/2009] [Indexed: 11/18/2022]
Abstract
BACKGROUND AND PURPOSE Focal adhesion kinase (FAK), a main player in integrin signaling and survival, is frequently overexpressed in human cancers and therefore postulated as potential target in cancer therapy. The aim of this study was to evaluate the radiosensitizing potential of the FAK inhibitor TAE226 in three-dimensional (3D) tumor cell cultures. MATERIALS AND METHODS Head and neck squamous cell carcinoma (HNSCC) cells (FaDu, UT-SCC15, UT-SCC45), lung cancer cells (A549), colorectal carcinoma cells (DLD-1, HCT-116) and pancreatic tumor cells (MiaPaCa2, Panc1) were treated with different concentrations of TAE226 (0-1mum; 1 or 24h) without or in combination with irradiation (0-6Gy, X-ray, single dose). Subsequently, 3D clonogenic survival assays (laminin-rich extracellular matrix) and Western blotting (expression/phosphorylation, e.g. FAK, Akt, ERK1/2) were performed. RESULTS All investigated 3D cell cultures showed a dose-dependent reduction in clonogenic survival by TAE226. Intriguingly, TAE226 only significantly radiosensitized 3D HNSCC cell cultures accompanied by a pronounced dephosphorylation of FAK, Akt and ERK1/2. CONCLUSIONS Our data demonstrate TAE226 as potent FAK inhibitor that enhances the cellular radiosensitivity particularly of HNSCC cells grown in a 3D cell culture model. Future in vitro and in vivo investigations will clarify, to which extent this approach might be clinically relevant for radiotherapy of HNSCC.
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Affiliation(s)
- Stephanie Hehlgans
- OncoRay-Center for Radiation Research in Oncology, Dresden University of Technology, Dresden, Germany
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159
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Winograd-Katz SE, Itzkovitz S, Kam Z, Geiger B. Multiparametric analysis of focal adhesion formation by RNAi-mediated gene knockdown. ACTA ACUST UNITED AC 2009; 186:423-36. [PMID: 19667130 PMCID: PMC2728402 DOI: 10.1083/jcb.200901105] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cell adhesion to the extracellular matrix is mediated by elaborate networks of multiprotein complexes consisting of adhesion receptors, cytoskeletal components, signaling molecules, and diverse adaptor proteins. To explore how specific molecular pathways function in the assembly of focal adhesions (FAs), we performed a high-throughput, high-resolution, microscopy-based screen. We used small interfering RNAs (siRNAs) to target human kinases, phosphatases, and migration- and adhesion-related genes. Multiparametric image analysis of control and of siRNA-treated cells revealed major correlations between distinct morphological FA features. Clustering analysis identified different gene families whose perturbation induced similar effects, some of which uncoupled the interfeature correlations. Based on these findings, we propose a model for the molecular hierarchy of FA formation, and tested its validity by dynamic analysis of FA formation and turnover. This study provides a comprehensive information resource on the molecular regulation of multiple cell adhesion features, and sheds light on signaling mechanisms regulating the formation of integrin adhesions.
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Affiliation(s)
- Sabina E Winograd-Katz
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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160
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Abstract
Integrin-mediated adhesion is as ancient as multicellularity, but it was not always as complex as it is in humans. Here, I examine the extent of conservation of 192 adhesome proteins across the genomes of nine model organisms spanning one and a half billion years of evolution. The work reveals that Rho GTPases, lipid- and serine/threonine-kinases, and phosphatases existed before integrins, but tyrosine phosphorylation developed concomitant with integrins. The expansion of specific functional groups such as GAPs, GEFs, adaptors, and receptors is demonstrated, along with the expansion of specific protein domains, such as SH3, PH, SH2, CH, and LIM. Expansion is due to gene duplication and creation of families of paralogues. Apparently, these paralogues share few partners and create new sets of interactions, thus increasing specificity and the repertoire of integrin-mediated signaling. Interestingly, the average number of interactions positively correlates with the evolutionary age of proteins. While shedding light on the evolution of adhesome complexity, this analysis also highlights the relevance and creates a framework for studying integrin-mediated adhesion in simpler model organisms.
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Affiliation(s)
- Ronen Zaidel-Bar
- Department of Zoology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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161
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Alghisi GC, Rüegg C. Vascular Integrins in Tumor Angiogenesis: Mediators and Therapeutic Targets. ACTA ACUST UNITED AC 2009; 13:113-35. [PMID: 16728329 DOI: 10.1080/10623320600698037] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The notion that tumor angiogenesis may have therapeutic implications in the control of tumor growth was introduced by Dr. Judah Folkman in 1971. The approval of Avastin in 2004 as the first antiangiogenic systemic drug to treat cancer patients came as a validation of this visionary concept and opened new perspectives to the treatment of cancer. In addition, this success boosted the field to the quest for new therapeutic targets and antiangiogenic drugs. Preclinical and clinical evidence indicate that vascular integrins may be valid therapeutic targets. In preclinical studies, pharmacological inhibition of integrin function efficiently suppressed angiogenesis and inhibited tumor progression. alphaVbeta3 and alphaVbeta5 were the first vascular integrins targeted to suppress tumor angiogenesis. Subsequent experiments revealed that at least four additional integrins (i.e., alpha1beta1, alpha2beta1, alpha5beta1, and alpha6beta4) might be potential therapeutic targets. In clinical studies low-molecular-weight integrin inhibitors and anti-integrin function-blocking antibodies demonstrated low toxicity and good tolerability and are now being tested in combination with radiotherapy and chemotherapy for anticancer activity in patients. In this article the authors review the role of integrins in angiogenesis, present recent development in the use of alphaVbeta3 and alpha5beta1 integrin antagonists as potential therapeutics in cancer, and discuss future perspectives.
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Affiliation(s)
- Gian Carlo Alghisi
- Centre Pluridisciplinaire d'Oncologie (CePO), Faculty of Biology and Medicine, University of Lausanne, Switzerland
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162
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Zhang H, Chen X, Bollag WB, Bollag RJ, Sheehan DJ, Chew CS. Lasp1 gene disruption is linked to enhanced cell migration and tumor formation. Physiol Genomics 2009; 38:372-85. [PMID: 19531578 DOI: 10.1152/physiolgenomics.00048.2009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Lasp1 is an actin-binding, signaling pathway-regulated phosphoprotein that is overexpressed in several cancers. siRNA knockdown in cell lines retards cell migration, suggesting the possibility that Lasp1 upregulation influences cancer metastasis. Herein, we utilized a recently developed gene knockout model to assess the role of Lasp1 in modulating nontransformed cell functions. Wound healing and tumor initiation progressed more rapidly in Lasp1(-/-) mice compared with Lasp1(+/+) controls. Embryonic fibroblasts (MEFs) derived from Lasp1(-/-) mice also migrated more rapidly in vitro. These MEFs characteristically possessed increased focal adhesion numbers and displayed more rapid attachment compared with wild-type MEFs. Differential microarray analyses revealed alterations in message expression for proteins implicated in cell migration, adhesion, and cytoskeletal organization. Notably, the focal adhesion protein, lipoma preferred partner (LPP), a zyxin family member and putative Lasp1 binding protein, was increased about twofold. Because LPP gene disruption reduces cell migration, we hypothesize that LPP plays a role in enhancing the migratory capacity of Lasp1(-/-) MEFs, perhaps by modifying the subcellular localization of other motility-associated proteins. The striking contrast in the functional effects of loss of Lasp1 in innate cells compared with cell lines reveals distinct differences in mechanisms of motility and attachment in these models.
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Affiliation(s)
- Han Zhang
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, Georgia, USA
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163
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Estrada-Bernal A, Gatlin JC, Sunpaweravong S, Pfenninger KH. Dynamic adhesions and MARCKS in melanoma cells. J Cell Sci 2009; 122:2300-10. [PMID: 19509053 DOI: 10.1242/jcs.047860] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Cell motility necessitates the rapid formation and disassembly of cell adhesions. We have studied adhesions in a highly motile melanoma cell line using various biochemical approaches and microscopic techniques to image close adhesions. We report that WM-1617 melanoma cells contain at least two types of close adhesion: classic focal adhesions and more extensive, irregularly shaped adhesions that tend to occur along lamellipodial edges. In contrast to focal adhesions, these latter adhesions are highly dynamic and can be disassembled rapidly via protein kinase C (PKC) activation (e.g. by eicosanoid) and MARCKS phosphorylation. MARCKS overexpression, however, greatly increases the area of close adhesions and renders them largely refractory to PKC stimulation. This indicates that nonphosphorylated MARCKS is an adhesion stabilizer. Unlike focal adhesions, the dynamic adhesions contain alpha3 integrin and MARCKS, but they do not contain the focal adhesion marker vinculin. Overall, these results begin to define the molecular and functional properties of dynamic close adhesions involved in cell motility.
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Affiliation(s)
- Adriana Estrada-Bernal
- Department of Pediatrics, University of Colorado School of Medicine, University of Colorado Cancer Center, and Colorado Intellectual and Developmental Disabilities Research Center, Aurora, CO 80045, USA
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164
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Kim H, Rhee SH, Pothoulakis C, LaMont JT. Clostridium difficile toxin A binds colonocyte Src causing dephosphorylation of focal adhesion kinase and paxillin. Exp Cell Res 2009; 315:3336-44. [PMID: 19481075 DOI: 10.1016/j.yexcr.2009.05.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Revised: 05/19/2009] [Accepted: 05/20/2009] [Indexed: 12/15/2022]
Abstract
Clostridium difficile toxin A impairs tight junction function of colonocytes by glucosylation of Rho family proteins causing actin filament disaggregation and cell rounding. We investigated the effect of toxin A on focal contact formation by assessing its action on focal adhesion kinase (FAK) and the adapter protein paxillin. Exposure of NCM460 human colonocytes to toxin A for 1 h resulted in complete dephosphorylation of FAK and paxillin, while protein tyrosine phosphatase activity was reduced. Blockage of toxin A-associated glucosyltransferase activity by co-incubation with UDP-2'3' dialdehyde did not reduce toxin A-induced FAK and paxillin dephosphorylation. GST-pull down and in vitro kinase activity experiments demonstrated toxin A binding directly to the catalytic domain of Src with suppression of its kinase activity. Direct binding of toxin A to Src, independent of any effect on protein tyrosine phosphatase or Rho glucosylation, inhibits Src kinase activity followed by FAK/paxillin inactivation. These mechanisms may contribute to toxin A inhibition of colonocyte focal adhesion that occurs in human colonic epithelium exposed to toxin A.
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Affiliation(s)
- Ho Kim
- Department of Life Science, College of Natural Science, Daejin University, Pochen, Kyungkido, Republic of Korea
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165
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Brew CT, Aronchik I, Kosco K, McCammon J, Bjeldanes LF, Firestone GL. Indole-3-carbinol inhibits MDA-MB-231 breast cancer cell motility and induces stress fibers and focal adhesion formation by activation of Rho kinase activity. Int J Cancer 2009; 124:2294-302. [PMID: 19173291 PMCID: PMC3400502 DOI: 10.1002/ijc.24210] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Indole-3-carbinol (I3C), a phytochemical derived from cruciferous vegetables such as broccoli and Brussels sprouts, has potent antiproliferative effects in human breast cancer cells and has been shown to decrease metastatic spread of tumors in experimental animals. Using chemotaxis and fluorescent-bead cell motility assays, we demonstrated that I3C significantly decreased the in vitro migration of MDA-MB-231 cells, a highly invasive breast cancer cell line. Immunofluorescence staining of the actin cytoskeleton revealed that concurrent with the loss of cell motility, I3C treatment significantly increased stress fiber formation. Furthermore, I3C induced the localization of the focal adhesion component vinculin and tyrosine-phosphorylated proteins to the cell periphery, which implicates an indole-dependent enhancement of focal adhesions within the outer boundary of the cells. Coimmunoprecipitation analysis of focal adhesion kinase demonstrated that I3C stimulated the dynamic formation of the focal adhesion protein complex without altering the total level of individual focal adhesion proteins. The RhoA-Rho kinase pathway is involved in stress fiber and focal adhesion formation, and I3C treatment stimulated Rho kinase enzymatic activity and cofilin phosphorylation, which is a downstream target of Rho kinase signaling, but did not increase the level of active GTP-bound RhoA. Exposure of MDA-MB-231 cells to the Rho kinase inhibitor Y-27632, or expression of dominant negative RhoA ablated the I3C induced formation of stress fibers and of peripheral focal adhesions. Expression of constitutively active RhoA mimicked the I3C effects on both processes. Taken together, our data demonstrate that I3C induces stress fibers and peripheral focal adhesions in a Rho kinase-dependent manner that leads to an inhibition of motility in human breast cancer cells.
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Affiliation(s)
- Christine T. Brew
- Department of Molecular and Cell Biology and The Cancer Research Laboratory, The University of California at Berkeley, Berkeley, CA 94720
| | - Ida Aronchik
- Department of Molecular and Cell Biology and The Cancer Research Laboratory, The University of California at Berkeley, Berkeley, CA 94720
| | - Karena Kosco
- Signal Transduction Program, The Burnham Institute, La Jolla, CA 92037
| | - Jasmine McCammon
- Department of Molecular and Cell Biology and The Cancer Research Laboratory, The University of California at Berkeley, Berkeley, CA 94720
| | - Leonard F. Bjeldanes
- Department of Nutritional Sciences and Toxicology, The University of California at Berkeley, Berkeley, CA 94720
| | - Gary L. Firestone
- Department of Molecular and Cell Biology and The Cancer Research Laboratory, The University of California at Berkeley, Berkeley, CA 94720
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166
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Divya Rani VV, Manzoor K, Menon D, Selvamurugan N, Nair SV. The design of novel nanostructures on titanium by solution chemistry for an improved osteoblast response. NANOTECHNOLOGY 2009; 20:195101. [PMID: 19420629 DOI: 10.1088/0957-4484/20/19/195101] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We report an interesting cell response to novel nanostructures formed on a titanium (Ti) surface by a simple non-lithographic bottom-up method. The surface topography of bio-implant materials dramatically influences their cell response. The aim of this study was to modify the surface of a titanium implant by a simple and cost effective processing technique and to determine its suitability for osteoblast attachment. A set of unique structures ranging from mesoporous nanoscaffolds, nanoflowers, nanoneedles, nanorods and octahedral bipyramids were fabricated by systematically tuning the hydrothermal conditions such as reaction medium composition, concentration, temperature and time duration. The cytotoxicity of surface modified Ti was assessed using human primary osteoblastic cells, and more than 90% of the cells were found to be viable after 24 h of incubation. Protein adsorption studies revealed that the surface modified nanostructures on titanium adsorbed more proteins, suggesting that they are capable of promoting cell adhesion/attachment. Immunofluorescence studies with vinculin antibody identified a distinctly different spread pattern of osteoblastic cells on hydrothermally modified nanostructured surfaces, indicating the formation of the focal adhesion points required for intracellular signaling. Thus, based on our results, we suggest that this study may present one of the best designs and systematic syntheses of biocompatible nanostructures on metallic Ti for orthopedic implant applications.
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Affiliation(s)
- V V Divya Rani
- Amrita Centre for Nanosciences, Amrita Institute of Medical Science and Research Centre, Amrita Vishwa Vidyapeetham, Cochin, Kerala, India
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167
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Zheng Z, Zhang L, Kong L, Wang A, Gong Y, Zhang X. The behavior of MC3T3-E1 cells on chitosan/poly-L-lysine composite films: Effect of nanotopography, surface chemistry, and wettability. J Biomed Mater Res A 2009; 89:453-65. [DOI: 10.1002/jbm.a.31979] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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168
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Trache A, Lim SM. Integrated microscopy for real-time imaging of mechanotransduction studies in live cells. JOURNAL OF BIOMEDICAL OPTICS 2009; 14:034024. [PMID: 19566317 DOI: 10.1117/1.3155517] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Mechanical force is an important stimulus and determinant of many vascular smooth muscle cell functions including contraction, proliferation, migration, and cell attachment. Transmission of force from outside the cell through focal adhesions controls the dynamics of these adhesion sites and initiates intracellular signaling cascades that alter cellular behavior. To understand the mechanism by which living cells sense mechanical forces, and how they respond and adapt to their environment, a critical first step is to develop a new technology to investigate cellular behavior at subcellular level that integrates an atomic force microscope (AFM) with total internal reflection fluorescence (TIRF) and fast-spinning disk (FSD) confocal microscopy, providing high spatial and temporal resolution. AFM uses a nanosensor to measure the cell surface topography and can apply and measure mechanical force with high precision. TIRF microscopy is an optical imaging technique that provides high-contrast images with high z-resolution of fluorescently labeled molecules in the immediate vicinity of the cell-coverslip interface. FSD confocal microscopy allows rapid 3-D imaging throughout the cell in real time. The integrated system is broadly applicable across a wide range of molecular dynamic studies in any adherent live cells, allowing direct optical imaging of cell responses to mechanical stimulation in real time.
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Affiliation(s)
- Andreea Trache
- Texas A&M Health Science Center, Cardiovascular Research Institute, College of Medicine, Department of Systems Biology and Translational Medicine, College Station, Texas 77843-1114, USA.
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169
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Zhu Y, Wu Y, Kim JI, Wang Z, Daaka Y, Nie Z. Arf GTPase-activating protein AGAP2 regulates focal adhesion kinase activity and focal adhesion remodeling. J Biol Chem 2009; 284:13489-13496. [PMID: 19318351 DOI: 10.1074/jbc.m900469200] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Focal adhesions are specialized sites of cell attachment to the extracellular matrix where integrin receptors link extracellular matrix to the actin cytoskeleton, and they are constantly remodeled during cell migration. Focal adhesion kinase (FAK) is an important regulator of focal adhesion remodeling. AGAP2 is an Arf GTPase-activating protein that regulates endosomal trafficking and is overexpressed in different human cancers. Here we examined the regulation of the FAK activity and the focal adhesion remodeling by AGAP2. Our results show that FAK binds the pleckstrin homology domain of AGAP2, and the binding is independent of FAK activation following epidermal growth factor receptor stimulation. Overexpression of AGAP2 augments the activity of FAK, and concordantly, the knockdown of AGAP2 expression with RNA interference attenuates the FAK activity stimulated by epidermal growth factor or platelet-derived growth factor receptors. AGAP2 is localized to the focal adhesions, and its overexpression results in dissolution of the focal adhesions, whereas knockdown of its expression stabilizes them. The AGAP2-induced dissolution of the focal adhesions is independent of its GTPase-activating protein activity but may involve its N-terminal G protein-like domain. Our results indicate that AGAP2 regulates the FAK activity and the focal adhesion disassembly during cell migration.
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Affiliation(s)
- Yunjuan Zhu
- Department of Pathology, Medical College of Georgia, Augusta, Georgia 30912
| | - Yuanjun Wu
- Department of Pathology, Medical College of Georgia, Augusta, Georgia 30912
| | - Jae I Kim
- Department of Pathology, Medical College of Georgia, Augusta, Georgia 30912
| | - Zhimin Wang
- Department of Pathology, Medical College of Georgia, Augusta, Georgia 30912
| | - Yehia Daaka
- Department of Pathology, Medical College of Georgia, Augusta, Georgia 30912
| | - Zhongzhen Nie
- Department of Pathology, Medical College of Georgia, Augusta, Georgia 30912.
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170
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Nishizuka M, Kishimoto K, Kato A, Ikawa M, Okabe M, Sato R, Niida H, Nakanishi M, Osada S, Imagawa M. Disruption of the novel gene fad104 causes rapid postnatal death and attenuation of cell proliferation, adhesion, spreading and migration. Exp Cell Res 2009; 315:809-19. [PMID: 19138685 DOI: 10.1016/j.yexcr.2008.12.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Revised: 11/09/2008] [Accepted: 12/12/2008] [Indexed: 11/29/2022]
Abstract
The molecular mechanisms at the beginning of adipogenesis remain unknown. Previously, we identified a novel gene, fad104 (factor for adipocyte differentiation 104), transiently expressed at the early stage of adipocyte differentiation. Since the knockdown of the expression of fad104 dramatically repressed adipogenesis, it is clear that fad104 plays important roles in adipocyte differentiation. However, the physiological roles of fad104 are still unknown. In this study, we generated fad104-deficient mice by gene targeting. Although the mice were born in the expected Mendelian ratios, all died within 1 day of birth, suggesting fad104 to be crucial for survival after birth. Furthermore, analyses of mouse embryonic fibroblasts (MEFs) prepared from fad104-deficient mice provided new insights into the functions of fad104. Disruption of fad104 inhibited adipocyte differentiation and cell proliferation. In addition, cell adhesion and wound healing assays using fad104-deficient MEFs revealed that loss of fad104 expression caused a reduction in stress fiber formation, and notably delayed cell adhesion, spreading and migration. These results indicate that fad104 is essential for the survival of newborns just after birth and important for cell proliferation, adhesion, spreading and migration.
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Affiliation(s)
- Makoto Nishizuka
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, Aichi 467-8603, Japan
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171
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Burghardt RC, Burghardt JR, Taylor JD, Reeder AT, Nguen BT, Spencer TE, Bayless KJ, Johnson GA. Enhanced focal adhesion assembly reflects increased mechanosensation and mechanotransduction at maternal–conceptus interface and uterine wall during ovine pregnancy. Reproduction 2009; 137:567-82. [DOI: 10.1530/rep-08-0304] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The integrity of the fetal–maternal interface is critical for proper fetal nourishment during pregnancy. Integrins are important adhesion molecules present at the interface during implantation; however,in vivoevidence for integrin activation and focal adhesion formation at the maternal–conceptus interface is limited. We hypothesized that focal adhesion assembly in uterine luminal epithelium (LE) and conceptus trophectoderm (Tr) results from integrin binding of extracellular matrix (ECM) at this interface to provide increased tensile forces and signaling to coordinate utero-placental development. An ovine model of unilateral pregnancy was used to evaluate mechanotransduction events leading to focal adhesion assembly at the maternal–conceptus interface and within the uterine wall. Animals were hysterectomized on days 40, 80, or 120 of pregnancy, and uteri immunostained for integrins (ITGAV, ITGA4, ITGA5, ITGB1, ITGB3, and ITGB5), ECM proteins (SPP1, LGALS15, fibronectin (FN), and vitronectin (VTN)), cytoskeletal molecules (ACTN and TLN1), and a signal generator (PTK2). Focal adhesion assembly in myometrium and stroma was also studied to provide a frame of reference for mechanical stretch of the uterine wall. Large focal adhesions containing aggregates of ITGAV, ITGA4, ITGA5, ITGB1, ITGB5, ACTN, and PTK2 were detected in interplacentomal uterine LE and Tr of gravid but not non-gravid uterine horns and increased during pregnancy. SPP1 and LGALS15, but not FN or VTN, were present along LE and Tr interfaces in both uterine horns. These data support the idea that focal adhesion assembly at the maternal–conceptus interface reflects adaptation to increasing forces caused by the growing fetus. Cooperative binding of multiple integrins to SPP1 deposited at the maternal–conceptus interface forms an adhesive mosaic to maintain a tight connection between uterine and placental surfaces along regions of epitheliochorial placentation in sheep.
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172
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Krsko P, McCann TE, Thach TT, Laabs TL, Geller HM, Libera MR. Length-scale mediated adhesion and directed growth of neural cells by surface-patterned poly(ethylene glycol) hydrogels. Biomaterials 2009; 30:721-9. [PMID: 19026443 PMCID: PMC3282616 DOI: 10.1016/j.biomaterials.2008.10.011] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Accepted: 10/13/2008] [Indexed: 11/26/2022]
Abstract
We engineered surfaces that permit the adhesion and directed growth of neuronal cell processes but that prevent the adhesion of astrocytes. This effect was achieved based on the spatial distribution of sub-micron-sized cell-repulsive poly(ethylene glycol) [PEG] hydrogels patterned on an otherwise cell-adhesive substrate. Patterns were identified that promoted cellular responses ranging from complete non-attachment, selective attachment, and directed growth at both cellular and subcellular length scales. At the highest patterning density where the individual hydrogels almost overlapped, there was no cellular adhesion. As the spacing between individual hydrogels was increased, patterns were identified where neurites could grow on the adhesive surface between hydrogels while astrocytes were unable to adhere. Patterns such as lines or arrays were identified that could direct the growth of these subcellular neuronal processes. At higher hydrogel spacings, both neurons and astrocytes adhered and grew in a manner approaching that of unpatterned control surfaces. Patterned lines could once again direct growth at cellular length scales. Significantly, we have demonstrated that the patterning of sub-micron/nano scale cell-repulsive features at microscale lengths on an otherwise cell-adhesive surface can differently control the adhesion and growth of cells and cell processes based on the difference in their characteristic sizes. This concept could potentially be applied to an implantable nerve-guidance device that would selectively enable regrowing axons to bridge a spinal-cord injury without interference from the glial scar.
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Affiliation(s)
- Peter Krsko
- Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, 1 Castle Point Terrace, Hoboken, NJ 07030, USA
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173
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Enhanced interaction between focal adhesion and adherens junction proteins: involvement in sphingosine 1-phosphate-induced endothelial barrier enhancement. Microvasc Res 2009; 77:304-13. [PMID: 19323978 DOI: 10.1016/j.mvr.2008.12.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 11/18/2008] [Accepted: 12/19/2008] [Indexed: 11/21/2022]
Abstract
Sphingosine 1-phosphate (S1P) is an important vascular barrier regulatory agonist which enhances the junctional integrity of human lung endothelial cell monolayers. We have now demonstrated that S1P induced cortical actin ring formation and redistribution of focal adhesion kinase (FAK) and paxillin to the cell periphery suggesting the critical role of cell-cell adhesion in endothelial barrier enhancement. Co-immunoprecipitation studies revealed increased association of VE-cadherin with FAK and paxillin in S1P-challenged human pulmonary artery endothelial cell (HPAEC) monolayers. Furthermore, S1P-induced enhancement of VE-cadherin interaction with alpha-catenin and beta-catenin was associated with the increased formation of FAK-beta-catenin protein complexes. Depletion of beta-catenin (siRNA) resulted in loss of S1P-mediated VE-cadherin association with FAK and paxillin rearrangement. Furthermore, transendothelial electrical resistance (an index of barrier function) demonstrated that beta-catenin siRNA significantly attenuated S1P-induced barrier enhancement. These results demonstrate a mechanism of S1P-induced endothelial barrier enhancement via beta-catenin-linked adherens junction and focal adhesion interaction.
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174
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Hule RA, Nagarkar RP, Altunbas A, Ramay HR, Branco MC, Schneider JP, Pochan DJ. Correlations between structure, material properties and bioproperties in self-assembled beta-hairpin peptide hydrogels. Faraday Discuss 2009; 139:251-64; discussion 309-25, 419-20. [PMID: 19048999 DOI: 10.1039/b717616c] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A de novo designed beta-hairpin peptide (MAX8), capable of undergoing intramolecular folding and consequent intermolecular self-assembly into a cytocompatible hydrogel, has been studied. A combination of small angle neutron scattering (SANS) and cryogenic-transmission electron microscopy (cryo-TEM) have been used to quantitatively investigate the MAX8 nanofibrillar hydrogel network morphology. A change in the peptide concentration from 0.5 to 2 wt% resulted in a denser fibrillar network as revealed via SANS by a change in the high q (q = (4 pi/lambda) x sin (theta/2), where lambda = wavelength of incident neutrons and theta = scattering angle) mass fractal exponent from 2.5 to 3 and by a decrease in the measured correlation length from 23 to 16 A. A slope of -4 in the USANS regime indicates well-defined gel microporosity, an important characteristic for cellular substrate applications. These changes, both at the network as well as the individual fibril lengthscales, can be directly visualized in situ by cryo-TEM. Fibrillar nanostructures and network properties are directly related to bulk hydrogel stiffness via oscillatory rheology. Preliminary cell viability and anchorage studies at varying hydrogel stiffness confirm cell adhesion at early stages of cell culture within the window of stiffness investigated. Knowledge of the precise structure spanning length scales from the nanoscale up to the microscale can help in the formation of future, specific structure-bioproperty relationships when studying in vitro and in vivo behavior of these new peptide scaffolds.
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Affiliation(s)
- Rohan A Hule
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA
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175
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Undyala VV, Dembo M, Cembrola K, Perrin BJ, Huttenlocher A, Elce JS, Greer PA, Wang YL, Beningo KA. The calpain small subunit regulates cell-substrate mechanical interactions during fibroblast migration. J Cell Sci 2008; 121:3581-8. [PMID: 18840650 PMCID: PMC3081789 DOI: 10.1242/jcs.036152] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cell migration involves the dynamic formation and release of cell-substrate adhesions, where the exertion and detection of mechanical forces take place. Members of the calpain family of calcium-dependent proteases are believed to have a central role in these processes, possibly through the regulation of focal adhesion dynamics. The ubiquitous calpains, calpain 1 (mu-calpain) and calpain 2 (m-calpain), are heterodimers consisting of large catalytic subunits encoded by the Capn1 and Capn2 genes, respectively, and the small regulatory subunit encoded by Capn4. We have examined the role of the calpain regulatory small subunit in traction force production and mechanosensing during cell migration. Capn4-deficient or rescued cells were plated on flexible polyacrylamide substrates, for both the detection of traction forces and the application of mechanical stimuli. The total force output of Capn4-deficient cells was approximately 75% lower than that of rescued cells and the forces were more randomly distributed and less dynamic in Capn4-deficient cells than in rescued cells. Furthermore, Capn4-deficient cells were less adhesive than wild-type cells and they also failed to respond to mechanical stimulations by pushing or pulling the flexible substrate, or by engaging dorsal receptors to the extracellular matrix. Surprisingly, fibroblasts deficient in calpain 1 or calpain 2 upon siRNA-mediated knockdown of Capn1 or Capn2, respectively, did not show the same defects in force production or adhesion, although they also failed to respond to mechanical stimulation. Interestingly, stress fibers were aberrant and also contained fewer colocalised vinculin-containing adhesions in Capn4-deficient cells than Capn1- and Capn2-knockdown cells. Together, these results suggest that the calpain small subunit plays an important role in the production of mechanical forces and in mediating mechanosensing during fibroblast migration. Furthermore, the Capn4 gene product might perform functions secondary to, or independent of, its role as a regulatory subunit for calpain 1 and calpain 2.
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Affiliation(s)
- Vishnu V. Undyala
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Micah Dembo
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Katherine Cembrola
- Department of Physiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Benjamin J. Perrin
- Department of Pediatrics and Pharmacology, University of Wisconsin Medical School, Madison, WI 53706, USA
| | - Anna Huttenlocher
- Department of Pediatrics and Pharmacology, University of Wisconsin Medical School, Madison, WI 53706, USA
| | - John S. Elce
- Department of Biochemistry Cancer Research Institute, Queen's University, Kingston, Ontario, K7L 3N6 Canada
| | - Peter A. Greer
- Department of Biochemistry Cancer Research Institute, Queen's University, Kingston, Ontario, K7L 3N6 Canada
- Department of Pathology and Molecular Medicine, Cancer Research Institute, Queen's University, Kingston, Ontario, K7L 3N6 Canada
| | - Yu-li Wang
- Department of Physiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Karen A. Beningo
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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176
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Du G, Frohman MA. A lipid-signaled myosin phosphatase surge disperses cortical contractile force early in cell spreading. Mol Biol Cell 2008; 20:200-8. [PMID: 18946083 DOI: 10.1091/mbc.e08-06-0555] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
When cells cease migrating through the vasculature, adhere to extracellular matrix, and begin to spread, they exhibit rapid changes in contraction and relaxation at peripheral regions newly contacting the underlying substrata. We describe here a requirement in this process for myosin II disassembly at the cell cortex via the action of myosin phosphatase (MP), which in turn is regulated by a plasma membrane signaling lipid. Cells in suspension exhibit high levels of activity of the signaling enzyme phospholipase D2 (PLD2), elevating production of the lipid second messenger phosphatidic acid (PA) at the plasma membrane, which in turn recruits MP and stores it there in a presumed inactive state. On cell attachment, down-regulation of PLD2 activity decreases PA production, leading to MP release, myosin dephosphorylation, and actomyosin disassembly. This novel model for recruitment and restraint of MP provides a means to effect a rapid cytoskeletal reorganization at the cell cortex upon demand.
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Affiliation(s)
- Guangwei Du
- Department of Pharmacology and Center for Developmental Genetics, Stony Brook University, Stony Brook, NY 11794
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177
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Kokubun K, Kashiwagi K, Yoshinari M, Inoue T, Shiba K. Motif-programmed artificial extracellular matrix. Biomacromolecules 2008; 9:3098-105. [PMID: 18826322 DOI: 10.1021/bm800638z] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Motif-programming is a method for creating artificial proteins by combining functional peptide motifs in a combinatorial manner. This method is particularly well suited for developing liaison molecules that interface between cells and inorganic materials. Here we describe our creation of artificial proteins through the programming of two motifs, a natural cell attachment motif (RGD) and an artificial Ti-binding motif (minTBP-1). The created proteins were found to reversibly bind Ti and to bind MC3T3-E1 osteoblast-like cells. Moreover, although the interaction with Ti was not covalent, the proteins recapitulated several functions of fibronectin, and thus, could serve as an artificial ECM on Ti materials. Because this motif-programming system could be easily extended to create artificial proteins having other biological functions and material specificities, it should be highly useful for application to tissue engineering and regenerative medicine.
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Affiliation(s)
- Katsutoshi Kokubun
- Department of Clinical Pathophysiology, Division of Oral Implants Research and Oral Health Science Center, Tokyo Dental College, 1-2-2, Masago, Mihama-ku, Chiba, 261-8501 Japan
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178
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Alexandrova AY, Arnold K, Schaub S, Vasiliev JM, Meister JJ, Bershadsky AD, Verkhovsky AB. Comparative dynamics of retrograde actin flow and focal adhesions: formation of nascent adhesions triggers transition from fast to slow flow. PLoS One 2008; 3:e3234. [PMID: 18800171 PMCID: PMC2535565 DOI: 10.1371/journal.pone.0003234] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Accepted: 07/24/2008] [Indexed: 12/22/2022] Open
Abstract
Dynamic actin network at the leading edge of the cell is linked to the extracellular matrix through focal adhesions (FAs), and at the same time it undergoes retrograde flow with different dynamics in two distinct zones: the lamellipodium (peripheral zone of fast flow), and the lamellum (zone of slow flow located between the lamellipodium and the cell body). Cell migration involves expansion of both the lamellipodium and the lamellum, as well as formation of new FAs, but it is largely unknown how the position of the boundary between the two flow zones is defined, and how FAs and actin flow mutually influence each other. We investigated dynamic relationship between focal adhesions and the boundary between the two flow zones in spreading cells. Nascent FAs first appeared in the lamellipodium. Within seconds after the formation of new FAs, the rate of actin flow decreased locally, and the lamellipodium/lamellum boundary advanced towards the new FAs. Blocking fast actin flow with cytochalasin D resulted in rapid dissolution of nascent FAs. In the absence of FAs (spreading on poly-L-lysine-coated surfaces) retrograde flow was uniform and the velocity transition was not observed. We conclude that formation of FAs depends on actin dynamics, and in its turn, affects the dynamics of actin flow by triggering transition from fast to slow flow. Extension of the cell edge thus proceeds through a cycle of lamellipodium protrusion, formation of new FAs, advance of the lamellum, and protrusion of the lamellipodium from the new base.
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Affiliation(s)
- Antonina Y. Alexandrova
- Ecole Polytechnique Fédérale de Lausanne, Laboratory of Cell Biophysics, Lausanne, Switzerland
- Belozersky Institute of Physical and Chemical Biology, Moscow State University, Moscow, Russia
| | - Katya Arnold
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, Israel
| | - Sébastien Schaub
- Ecole Polytechnique Fédérale de Lausanne, Laboratory of Cell Biophysics, Lausanne, Switzerland
- Institut “Biologie du Développement et Cancer” UMR 6543–CNRS, Nice, France
| | - Jury M. Vasiliev
- Belozersky Institute of Physical and Chemical Biology, Moscow State University, Moscow, Russia
- Cancer Research Center, Russian Academy of Medical Sciences, Moscow, Russia
| | - Jean-Jacques Meister
- Ecole Polytechnique Fédérale de Lausanne, Laboratory of Cell Biophysics, Lausanne, Switzerland
| | - Alexander D. Bershadsky
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, Israel
- * E-mail: (ADB); (ABV)
| | - Alexander B. Verkhovsky
- Ecole Polytechnique Fédérale de Lausanne, Laboratory of Cell Biophysics, Lausanne, Switzerland
- * E-mail: (ADB); (ABV)
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179
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Sharma A, Mayer BJ. Phosphorylation of p130Cas initiates Rac activation and membrane ruffling. BMC Cell Biol 2008; 9:50. [PMID: 18793427 PMCID: PMC2553404 DOI: 10.1186/1471-2121-9-50] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Accepted: 09/15/2008] [Indexed: 12/27/2022] Open
Abstract
Background Non-receptor tyrosine kinases (NTKs) regulate physiological processes such as cell migration, differentiation, proliferation, and survival by interacting with and phosphorylating a large number of substrates simultaneously. This makes it difficult to attribute a particular biological effect to the phosphorylation of a particular substrate. We developed the Functional Interaction Trap (FIT) method to phosphorylate specifically a single substrate of choice in living cells, thereby allowing the biological effect(s) of that phosphorylation to be assessed. In this study we have used FIT to investigate the effects of specific phosphorylation of p130Cas, a protein implicated in cell migration. We have also used this approach to address a controversy regarding whether it is Src family kinases or focal adhesion kinase (FAK) that phosphorylates p130Cas in the trimolecular Src-FAK-p130Cas complex. Results We show here that SYF cells (mouse fibroblasts lacking the NTKs Src, Yes and Fyn) exhibit a low level of basal tyrosine phosphorylation at focal adhesions. FIT-mediated tyrosine phosphorylation of NTK substrates p130Cas, paxillin and FAK and cortactin was observed at focal adhesions, while FIT-mediated phosphorylation of cortactin was also seen at the cell periphery. Phosphorylation of p130Cas in SYF cells led to activation of Rac1 and increased membrane ruffling and lamellipodium formation, events associated with cell migration. We also found that the kinase activity of Src and not FAK is essential for phosphorylation of p130Cas when the three proteins exist as a complex in focal adhesions. Conclusion These results demonstrate that tyrosine phosphorylation of p130Cas is sufficient for its localization to focal adhesions and for activation of downstream signaling events associated with cell migration. FIT provides a valuable tool to evaluate the contribution of individual components of the response to signals with multiple outputs, such as activation of NTKs.
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Affiliation(s)
- Alok Sharma
- Department of Pharmaceutical Sciences, Massachusetts College of Pharmacy and Health Sciences, 1260 Elm Street, Manchester, NH 03101, USA.
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180
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Stéphanou A, Mylona E, Chaplain M, Tracqui P. A computational model of cell migration coupling the growth of focal adhesions with oscillatory cell protrusions. J Theor Biol 2008; 253:701-16. [DOI: 10.1016/j.jtbi.2008.04.035] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Revised: 03/07/2008] [Accepted: 04/24/2008] [Indexed: 11/15/2022]
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181
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Pouthas F, Girard P, Lecaudey V, Ly TBN, Gilmour D, Boulin C, Pepperkok R, Reynaud EG. In migrating cells, the Golgi complex and the position of the centrosome depend on geometrical constraints of the substratum. J Cell Sci 2008; 121:2406-14. [DOI: 10.1242/jcs.026849] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Although cells migrate in a constrained 3D environment in vivo, in-vitro studies have mainly focused on the analysis of cells moving on 2D substrates. Under such conditions, the Golgi complex is always located towards the leading edge of the cell, suggesting that it is involved in the directional movement. However, several lines of evidence indicate that this location can vary depending on the cell type, the environment or the developmental processes. We have used micro contact printing (μCP) to study the migration of cells that have a geometrically constrained shape within a polarized phenotype. Cells migrating on micropatterned lines of fibronectin are polarized and migrate in the same direction. Under such conditions, the Golgi complex and the centrosome are located behind the nucleus. In addition, the Golgi complex is often displaced several micrometres away from the nucleus. Finally, we used the zebrafish lateral line primordium as an in-vivo model of cells migrating in a constrained environment and observe a similar localization of both the Golgi and the centrosome in the leading cells. We propose that the positioning of the Golgi complex and the centrosome depends on the geometrical constraints applied to the cell rather than on a precise migratory function in the leading region.
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Affiliation(s)
- François Pouthas
- Cell Biology and Cell Biophysics Programme, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Philippe Girard
- Cell Biology and Cell Biophysics Programme, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Virginie Lecaudey
- Cell Biology and Cell Biophysics Programme, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Thi Bach Nga Ly
- Cell Biology and Cell Biophysics Programme, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Darren Gilmour
- Cell Biology and Cell Biophysics Programme, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Christian Boulin
- Cell Biology and Cell Biophysics Programme, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Rainer Pepperkok
- Cell Biology and Cell Biophysics Programme, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Emmanuel G. Reynaud
- Cell Biology and Cell Biophysics Programme, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
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182
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Gunst SJ, Zhang W. Actin cytoskeletal dynamics in smooth muscle: a new paradigm for the regulation of smooth muscle contraction. Am J Physiol Cell Physiol 2008; 295:C576-87. [PMID: 18596210 DOI: 10.1152/ajpcell.00253.2008] [Citation(s) in RCA: 267] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A growing body of data supports a view of the actin cytoskeleton of smooth muscle cells as a dynamic structure that plays an integral role in regulating the development of mechanical tension and the material properties of smooth muscle tissues. The increase in the proportion of filamentous actin that occurs in response to the stimulation of smooth muscle cells and the essential role of stimulus-induced actin polymerization and cytoskeletal dynamics in the generation of mechanical tension has been convincingly documented in many smooth muscle tissues and cells using a wide variety of experimental approaches. Most of the evidence suggests that the functional role of actin polymerization during contraction is distinct and separately regulated from the actomyosin cross-bridge cycling process. The molecular basis for the regulation of actin polymerization and its physiological roles may vary in diverse types of smooth muscle cells and tissues. However, current evidence supports a model for smooth muscle contraction in which contractile stimulation initiates the assembly of cytoskeletal/extracellular matrix adhesion complex proteins at the membrane, and proteins within this complex orchestrate the polymerization and organization of a submembranous network of actin filaments. This cytoskeletal network may serve to strengthen the membrane for the transmission of force generated by the contractile apparatus to the extracellular matrix, and to enable the adaptation of smooth muscle cells to mechanical stresses. Better understanding of the physiological function of these dynamic cytoskeletal processes in smooth muscle may provide important insights into the physiological regulation of smooth muscle tissues.
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Affiliation(s)
- Susan J Gunst
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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183
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Identification of a fibrin-independent platelet contractile mechanism regulating primary hemostasis and thrombus growth. Blood 2008; 112:90-9. [DOI: 10.1182/blood-2007-12-127001] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractA fundamental property of platelets is their ability to transmit cytoskeletal contractile forces to extracellular matrices. While the importance of the platelet contractile mechanism in regulating fibrin clot retraction is well established, its role in regulating the primary hemostatic response, independent of blood coagulation, remains ill defined. Real-time analysis of platelet adhesion and aggregation on a collagen substrate revealed a prominent contractile phase during thrombus development, associated with a 30% to 40% reduction in thrombus volume. Thrombus contraction developed independent of thrombin and fibrin and resulted in the tight packing of aggregated platelets. Inhibition of the platelet contractile mechanism, with the myosin IIA inhibitor blebbistatin or through Rho kinase antagonism, markedly inhibited thrombus contraction, preventing the tight packing of aggregated platelets and undermining thrombus stability in vitro. Using a new intravital hemostatic model, we demonstrate that the platelet contractile mechanism is critical for maintaining the integrity of the primary hemostatic plug, independent of thrombin and fibrin generation. These studies demonstrate an important role for the platelet contractile mechanism in regulating primary hemostasis and thrombus growth. Furthermore, they provide new insight into the underlying bleeding diathesis associated with platelet contractility defects.
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184
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Pathak A, Deshpande VS, McMeeking RM, Evans AG. The simulation of stress fibre and focal adhesion development in cells on patterned substrates. J R Soc Interface 2008; 5:507-24. [PMID: 17939980 PMCID: PMC2375958 DOI: 10.1098/rsif.2007.1182] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The remodelling of the cytoskeleton and focal adhesion (FA) distributions for cells on substrates with micro-patterned ligand patches is investigated using a bio-chemo-mechanical model. We investigate the effect of ligand pattern shape on the cytoskeletal arrangements and FA distributions for cells having approximately the same area. The cytoskeleton model accounts for the dynamic rearrangement of the actin/myosin stress fibres. It entails the highly nonlinear interactions between signalling, the kinetics of tension-dependent stress-fibre formation/dissolution and stress-dependent contractility. This model is coupled with another model that governs FA formation and accounts for the mechano-sensitivity of the adhesions from thermodynamic considerations. This coupled modelling scheme is shown to capture a variety of key experimental observations including: (i) the formation of high concentrations of stress fibres and FAs at the periphery of circular and triangular, convex-shaped ligand patterns; (ii) the development of high FA concentrations along the edges of the V-, T-, Y- and U-shaped concave ligand patterns; and (iii) the formation of highly aligned stress fibres along the non-adhered edges of cells on the concave ligand patterns. When appropriately calibrated, the model also accurately predicts the radii of curvature of the non-adhered edges of cells on the concave-shaped ligand patterns.
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Affiliation(s)
- Amit Pathak
- Department of Mechanical Engineering, University of California, Santa Barbara, CA 93106, USA
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185
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Blanchemain N, Chai F, Haulon S, Krump-Konvalinkova V, Traisnel M, Morcellet M, Martel B, Kirkpatrick CJ, Hildebrand HF. Biological behaviour of an endothelial cell line (HPMEC) on vascular prostheses grafted with hydroxypropylgamma-cyclodextrine (HPgamma-CD) and hydroxypropylbeta-cyclodextrine (HPbeta-CD). JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2008; 19:2515-2523. [PMID: 18266086 DOI: 10.1007/s10856-008-3388-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Accepted: 01/18/2008] [Indexed: 05/25/2023]
Abstract
The cytocompatibility of cyclodextrins (CDs) grafting on vascular polyester (PET) prostheses for further loading with biomolecules was investigated in this study. Viability tests demonstrated no toxicity of HP-CDs and PolyHP-CDs at 4,000 mg/l with survival rates of 80 to 96%. Proliferation tests using the human pulmonary microvascular endothelial cell line (HPMEC-ST1) revealed an excellent biocompatibility for Melinex (Film form of PET). For Polythese and Polymaille, a good proliferation rate was observed at 3 days (60-80%) but decreased at 6 days (56-73%). For all CD-grafted samples, low proliferation rates were observed after 6 days (35-38%). Vitality tests revealed excellent functional capacities of HPMEC cells after 3 and 6 days for all samples. Adhesion kinetics tests showed a similar adhesion of HPMEC cells on control and Melinex. A low adhesion was observed on Polythese and especially on Polymaille compared to control. After CD grafting, the cell adhesion was decreased. The woven or knitted architecture and CD grafting were the most likely causes of this weak adhesion. The adhesion kinetic test was confirmed by SEM observations and immunocytochemistry. The low proliferation of HPMEC on virgin prostheses and especially on grafted prostheses was not due to a cytotoxic effect, but to the physical surface characteristics of the prostheses.
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Affiliation(s)
- N Blanchemain
- Faculté de Médecine, Laboratoire de Biophysique EA 1049, Groupe de Recherche sur les Biomatériaux, University Lille-2, 59045 Cedex, Lille, France
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186
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Suzuki M, Miura K, Tanaka T. The virus-like particles of a braconid endoparasitoid wasp, Meteorus pulchricornis, inhibit hemocyte spreading in its noctuid host, Pseudaletia separata. JOURNAL OF INSECT PHYSIOLOGY 2008; 54:1015-22. [PMID: 18501922 DOI: 10.1016/j.jinsphys.2008.03.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2008] [Revised: 03/31/2008] [Accepted: 03/31/2008] [Indexed: 05/21/2023]
Abstract
We previously reported that the virus-like particles of Meteorus pulchricornis (MpVLPs) are capable of inducing apoptosis by around 6h in the hemocytes of the host, Pseudaletia separata [Suzuki, M., Tanaka, T., 2006. Virus-like particles in venom of Meteorus pulchricornis induce host hemocyte apoptosis. Journal of Insect Physiology 52, 602-611], thereby protecting the oviposited egg. In the present study, we focused on analyses of the earlier events caused by the MpVLPs upon the host immune response, namely their effects on hemocyte spreading. After recognition and attachment on foreign substance, the granulocytes and plasmatocytes assemble focal complexes and focal adhesions and spread by protruding filopodia/lamellipodia. The well-spread, cultured hemocytes were subjected to MpVLPs exposure, and the morphological changes were observed. The granulocytes lost the focal complexes/adhesions visualized as phosphotyrosine clusters and retracted the filopodia/lamellipodia within 30min after exposure, while the plasmatocytes exhibited similar but distinct responses. The two hemocyte species prepared from either parasitized or MpVLP-injected hosts lost the ability to form both filopodia/lamellipodia and phosphotyrosine clusters. A caspase inhibitor, Z-VAD-FMK, did not affect these MpVLP-induced morphological changes, indicating that these earlier changes found in the hemocytes precede apoptosis. The present study together with our previous data has established that the attenuation of host immune defense by the MpVLPs comprises at least two temporally distinguishable phases: immediate and early inhibition of hemocyte spreading and the eventual induction of hemocyte apoptosis.
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Affiliation(s)
- M Suzuki
- Applied Entomology, Graduate School of Bio-Agricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
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187
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Read DE, Reed Herbert K, Gorman AM. Heat shock enhances NGF-induced neurite elongation which is not mediated by Hsp25 in PC12 cells. Brain Res 2008; 1221:14-23. [PMID: 18561899 DOI: 10.1016/j.brainres.2008.05.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Revised: 04/01/2008] [Accepted: 05/13/2008] [Indexed: 12/31/2022]
Abstract
Neuronal differentiation and neurite outgrowth are key processes during development of the nervous system. Understanding the regulation of neurite outgrowth stimulated by neurotrophins is crucial to developing therapies to promote axon regeneration after injury or in neurodegenerative diseases. Treatment of PC12 cells with nerve growth factor (NGF) stimulates them to extend neurites and differentiate into a sympathetic neuron-like phenotype. In this study we found that exposure of PC12 cells to 42 degrees C for 1 h significantly enhanced NGF-induced neurite elongation, but not branching. This heat shock treatment led to induction of heat shock protein 25 (Hsp25) and Hsp70. The morphological changes induced by NGF were accompanied by increased Hsp25 mRNA levels, in addition to elevation in Hsp25 protein expression and phosphorylation, without a concomitant increase in Hsp70. A possible role for Hsp25 in NGF-stimulated neurite outgrowth was investigated. However, quantification of NGF-induced neurite elongation and branching revealed that neither of these features were altered in PC12 cells which stably overexpressed human Hsp27 (to mimic heat shock induction of Hsp25). Similarly, knockdown of Hsp25 using siRNA had no effect on NGF-induced neurite outgrowth. Inhibition of p38 MAPK signalling with SB202190 blocked phosphorylation of Hsp25 without affecting NGF-induced neurite outgrowth or the heat shock-dependent enhancement of elongation. These findings indicate that Hsp25 is not required for NGF-induced neurite outgrowth in PC12 cells and is not responsible for the heat shock-enhancement of NGF-induced neurite elongation. Instead, inhibition of MEK1/2 with U0126 partially reduced the heat shock-enhancement of NGF-stimulated neurite elongation.
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Affiliation(s)
- Danielle E Read
- Department of Biochemistry, National University of Ireland, Galway, Ireland
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188
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Zhang ZM, Simmerman JA, Guibao CD, Zheng JJ. GIT1 paxillin-binding domain is a four-helix bundle, and it binds to both paxillin LD2 and LD4 motifs. J Biol Chem 2008; 283:18685-93. [PMID: 18448431 DOI: 10.1074/jbc.m801274200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The G protein-coupled receptor kinase-interacting protein 1 (GIT1) is a multidomain protein that plays an important role in cell adhesion, motility, cytoskeletal remodeling, and membrane trafficking. GIT1 mediates the localization of the p21-activated kinase (PAK) and PAK-interactive exchange factor to focal adhesions, and its activation is regulated by the interaction between its C-terminal paxillin-binding domain (PBD) and the LD motifs of paxillin. In this study, we determined the solution structure of rat GIT1 PBD by NMR spectroscopy. The PBD folds into a four-helix bundle, which is structurally similar to the focal adhesion targeting and vinculin tail domains. Previous studies showed that GIT1 interacts with paxillin through the LD4 motif. Here, we demonstrated that in addition to the LD4 motif, the GIT1 PBD can also bind to the paxillin LD2 motif, and both LD2 and LD4 motifs competitively target the same site on the PBD surface. We also revealed that paxillin Ser(272) phosphorylation does not influence GIT1 PBD binding in vitro. These results are in agreement with the notion that phosphorylation of paxillin Ser(272) plays an essential role in regulating focal adhesion turnover.
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Affiliation(s)
- Ziwei M Zhang
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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189
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Kalinina S, Gliemann H, López-García M, Petershans A, Auernheimer J, Schimmel T, Bruns M, Schambony A, Kessler H, Wedlich D. Isothiocyanate-functionalized RGD peptides for tailoring cell-adhesive surface patterns. Biomaterials 2008; 29:3004-13. [PMID: 18433862 DOI: 10.1016/j.biomaterials.2008.04.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Accepted: 04/01/2008] [Indexed: 01/08/2023]
Abstract
With the advances made in surface patterning by micro- and nanotechnology, alternative methods to immobilize biomolecules for different purposes are highly desired. RGD peptides are commonly used to create cell-attractive surfaces for cell-biological and also medical applications. We have developed a fast, one-step method to bind RGD peptides covalently to surfaces by thiourea formation, which can be applied to structured and unstructured materials. RGD peptides were fused to an isothiocyanate anchor during synthesis and directly immobilized on amino-terminated surfaces. The spreading behavior of fibroblasts and the formation of focal contacts served to prove the applicability of the coupling method. Two different linear peptides and one cyclic peptide were compared. All the peptides induced spreading behavior and the formation of focal contacts in murine fibroblasts. Adhesion was specific as cells neither recognized the corresponding negative control peptides nor spread in the presence of soluble H-RGDS-OH peptide. We successfully applied our coupling method to functionalize surface patterns created by microcontact printing (microCP) and chemical etching. Cells recognize areas selectively coated with RGD-containing peptides, proliferate and maintain this preference during long-term cultivation. Our method significantly facilitates surface modification with any kind of peptide - even for the preparation of peptide-functionalized small surface areas.
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Affiliation(s)
- Sviatlana Kalinina
- Institut für Zoologie II (Entwicklungs- und Zellphysiologie), Universität Karlsruhe (TH), Karlsruhe, Germany
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190
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Papp S, Szabo E, Kim H, McCulloch CA, Opas M. Kinase-dependent adhesion to fibronectin: Regulation by calreticulin. Exp Cell Res 2008; 314:1313-26. [DOI: 10.1016/j.yexcr.2008.01.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 12/11/2007] [Accepted: 01/07/2008] [Indexed: 11/17/2022]
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191
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Abstract
Cell colonization is an important in a wide variety of biological processes and applications including vascularization, wound healing, tissue engineering, stem cell differentiation and biosensors. During colonization porous 3D structures are used to support and guide the ingrowth of cells into the matrix. In this review, we summarize our understanding of various factors affecting cell colonization in three-dimensional environment. The structural, biological and degradation properties of the matrix all play key roles during colonization. Further, specific scaffold properties such as porosity, pore size, fiber thickness, topography and scaffold stiffness as well as important cell material interactions such as cell adhesion and mechanotransduction also influence colonization.
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Affiliation(s)
- Benjamin J Lawrence
- School of Chemical Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, USA
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192
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Chan EWL, Yousaf MN. A photo-electroactive surface strategy for immobilizing ligands in patterns and gradients for studies of cell polarization. MOLECULAR BIOSYSTEMS 2008; 4:746-53. [DOI: 10.1039/b801394b] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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193
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Abstract
The c-Src non-receptor tyrosine kinase is overexpressed in a large number of human malignancies. It is linked to tumour development and progression to distant metastases by promoting cell proliferation, invasion, and motility. Recently, promising anticancer therapeutics targeting c-Src have been developed that are under clinical investigation.
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Affiliation(s)
- A Hilbig
- Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Medizinische Klinik mit Schwerpunkt Hämatologie und Onkologie, Germany
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194
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Chapter Eight Cytoskeletal Proteins at the Lipid Membrane. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/s1554-4516(07)06008-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
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195
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Integrins in Angiogenesis. Angiogenesis 2008. [DOI: 10.1007/978-0-387-71518-6_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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196
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Melton AC, Soon RK, Park JG, Martinez L, Dehart GW, Yee HF. Focal adhesion disassembly is an essential early event in hepatic stellate cell chemotaxis. Am J Physiol Gastrointest Liver Physiol 2007; 293:G1272-80. [PMID: 17947456 DOI: 10.1152/ajpgi.00134.2007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Chemotaxis (i.e., directed migration) of hepatic stellate cells to areas of inflammation is a requisite event in the liver's response to injury. Previous studies of signaling pathways that regulate stellate cell migration suggest a key role for focal adhesions, but the exact function of these protein complexes in motility remains unclear. Focal adhesions attach a cell to its substrate and therefore must be regulated in a highly coordinated manner during migration. To test the hypothesis that focal adhesion turnover is an essential early event for chemotaxis in stellate cells, we employed a live-cell imaging technique in which chemotaxis was induced by locally stimulating the tips of rat stellate cell protrusions with platelet-derived growth factor-BB (PDGF). Focal adhesions were visualized with an antibody directed against vinculin, a structural component of the focal adhesion complex. PDGF triggered rapid disassembly of adhesions within 6.25 min, subsequent reassembly by 12.5 min, and continued adhesion assembly in concert with the spreading protrusion until the completion of chemotaxis. Blockade of adhesion disassembly by growing cells on fibronectin or treatment with nocodazole prevented a chemotactic response to PDGF. Augmentation of adhesion disassembly with ML-7 enhanced the chemotactic response to PDGF. These data suggest that focal adhesion disassembly is an essential early event in stellate cell chemotaxis in response to PDGF.
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Affiliation(s)
- Andrew C Melton
- Department of Medicine and Liver Center, University of California San Francisco, San Francisco, California, USA
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197
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Ko HC, Han JS, Bächle M, Jang JH, Shin SW, Kim DJ. Initial osteoblast-like cell response to pure titanium and zirconia/alumina ceramics. Dent Mater 2007; 23:1349-55. [PMID: 17197017 DOI: 10.1016/j.dental.2006.11.023] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Revised: 11/11/2006] [Accepted: 11/16/2006] [Indexed: 11/19/2022]
Abstract
OBJECTIVES Outstanding mechanical properties, resistance to scratching and high biocompatibility make zirconia/alumina ceramics interesting for dental applications. To solve the problem of the well-known low temperature degradation and to provide stable mechanical properties a novel zirconia alloy ((Y,Nb)-TZP/alumina) was developed. The aim of this study was to investigate the initial bone cell response to this new zirconia/alumina composite ceramic. METHODS HOS cells were cultured on zirconia/alumina composite (Zc) and pure titanium (Ti) discs. Surface topography was examined by atomic force microscopy (AFM), cell morphology by scanning electron microscopy (SEM). Cell proliferation (MTS) and alkaline phosphatase activity was measured at 1, 4 and 8 days. The mRNA expression of Cycline D1, the cell cycle regulating gene, integrin beta 1, osteonectin (ON) and beta-actin were evaluated by RT-PCR analysis after 12, 24 and 48 h. RESULTS Both substrates showed a very smooth character with R(a)-values in the range of 0.002-0.113 microm supporting a continuous cellular growth. After 8 days, cell proliferation on Zc was higher than on Ti. The mRNA expression of cyclin D1 showed similar activity after 48 h on both surfaces, ALP activity was higher on Zc after 8 days. ON expression however showed no difference between the two groups. SIGNIFICANCE Our data demonstrate that this new zirconia composite ceramic showed at least equivalent or slightly better biological response of osteoblast-like HOS cells than pure titanium during a short-time cell culture period.
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Affiliation(s)
- Hee-Cheol Ko
- Department of Oral Rehabilitation, Graduate School, Korea University, Republic of Korea
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198
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Szabo E, Papp S, Opas M. Differential calreticulin expression affects focal contacts via the calmodulin/CaMK II pathway. J Cell Physiol 2007; 213:269-77. [PMID: 17516550 DOI: 10.1002/jcp.21122] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Calreticulin is an ER calcium-storage protein, which influences gene expression and cell adhesion. In this study, we analysed the differences in adhesive properties of calreticulin under- and overexpressing fibroblasts in relation to the calmodulin- and calcium/calmodulin-dependent kinase II (CaMK II)-dependent signalling pathways. Cells stably underexpressing calreticulin had elevated expression of calmodulin, activated CaMK II, activated ERK and activated c-src. Inhibition of calmodulin by W7, and CaMK II by KN-62, caused the otherwise weekly adhesive calreticulin underexpressing cells to behave like the overexpressing cells, via induction of increased cell spreading. Increased vinculin, activated paxillin, activated focal adhesion kinase and fibronectin levels were observed upon inhibition of either the calmodulin or the CaMK II signalling pathways, which was accompanied by an increase in cell spreading and focal contact formation. Both KN-62 and W7 treatment increased cell motility in underexpressing cells, but W7 treatment led to loss of directionality. Thus, both the calmodulin and CaMK II signalling pathways influence cellular spreading and motility, but subtle differences exist in their distal effects on motility effectors.
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Affiliation(s)
- Eva Szabo
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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199
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Sakamoto N, Yamazaki Y, Ohashi T, Sato M. Effect of Mechanical Environment of Focal Adhesions on Remodeling of Endothelial Cells Subjected to Cyclic Stretching Using Microsubstrates. JOURNAL OF ROBOTICS AND MECHATRONICS 2007. [DOI: 10.20965/jrm.2007.p0557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Endothelial cells (ECs) adapt to mechanical environments such as cyclic stretching by altering their morphology and cytoskeletal structure. The detailed mechanism underlying EC remodeling in response to cyclic stretching, however, remains unclear. To understand the contribution of strain in contact area between focal adhesions (FAs) and the substrate to morphological and cytoskeletal changes in cells, we applied cyclic stretching to ECs using a microsubstrate with arrays of micropillars on which cells were selectively stretched between FAs but FA-substrate contact area were hardly stretched. Bovine aortic ECs were seeded on a silicone elastomer micropillar substrate in a silicone chamber. ECs were then subjected to 20% stretching at 0.5 Hz for up to 6 h using a stretching apparatus. Cells stretched on a flat substrate were also observed. Under static conditions, no significant difference was seen in EC morphology between flat and micropillar substrates. After exposure to cyclic stretching for 3 h, ECs on both flat and micropillar substrates were aligned perpendicular to the direction of stretching. Stress fibers were oriented about 60° to the direction of stretching on the flat substrate, while stress fibers were not aligned in any direction for the micropillar substrate. After 6 h of stretching, stress fibers on the micropillar substrate were oriented approximately 90° to the direction of stretching. These results suggest that strain in contact area between FAs and the substrate may have an impact on reorientation rates of stress fibers in ECs in response to cyclic stretching.
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200
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Peyton SR, Ghajar CM, Khatiwala CB, Putnam AJ. The emergence of ECM mechanics and cytoskeletal tension as important regulators of cell function. Cell Biochem Biophys 2007; 47:300-20. [PMID: 17652777 DOI: 10.1007/s12013-007-0004-y] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 12/17/2022]
Abstract
The ability to harvest and maintain viable cells from mammalian tissues represented a critical advance in biomedical research, enabling individual cells to be cultured and studied in molecular detail. However, in these traditional cultures, cells are grown on rigid glass or polystyrene substrates, the mechanical properties of which often do not match those of the in vivo tissue from which the cells were originally derived. This mechanical mismatch likely contributes to abrupt changes in cellular phenotype. In fact, it has been proposed that mechanical changes in the cellular microenvironment may alone be responsible for driving specific cellular behaviors. Recent multidisciplinary efforts from basic scientists and engineers have begun to address this hypothesis more explicitly by probing the effects of ECM mechanics on cell and tissue function. Understanding the consequences of such mechanical changes is physiologically relevant in the context of a number of tissues in which altered mechanics may either correlate with or play an important role in the onset of pathology. Examples include changes in the compliance of blood vessels associated with atherosclerosis and intimal hyperplasia, as well as changes in the mechanical properties of developing tumors. Compelling evidence from 2-D in vitro model systems has shown that substrate mechanical properties induce changes in cell shape, migration, proliferation, and differentiation, but it remains to be seen whether or not these same effects translate to 3-D systems or in vivo. Furthermore, the molecular "mechanotransduction" mechanisms by which cells respond to changes in ECM mechanics remain unclear. Here, we provide some historical context for this emerging area of research, and discuss recent evidence that regulation of cytoskeletal tension by changes in ECM mechanics (either directly or indirectly) may provide a critical switch that controls cell function.
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Affiliation(s)
- Shelly R Peyton
- Department of Chemical Engineering and Materials Science, The Henry Samueli School of Engineering, University of California, Irvine, CA 92697-2715, USA
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