1
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Lee D, Kim HS, Kim HU, Song HJ, Lee C, Kim DY, Chun HM, Jang WY, Jang B. Expression profile of CD98 heavy chain and L-type amino acid transporter 1 and its prognostic significance in colorectal cancer. Pathol Res Pract 2022; 229:153730. [DOI: 10.1016/j.prp.2021.153730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 11/29/2021] [Accepted: 11/30/2021] [Indexed: 12/20/2022]
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2
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Parisi MG, Parrinello D, Stabili L, Cammarata M. Cnidarian Immunity and the Repertoire of Defense Mechanisms in Anthozoans. BIOLOGY 2020; 9:E283. [PMID: 32932829 PMCID: PMC7563517 DOI: 10.3390/biology9090283] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/04/2020] [Accepted: 09/04/2020] [Indexed: 02/07/2023]
Abstract
Anthozoa is the most specious class of the phylum Cnidaria that is phylogenetically basal within the Metazoa. It is an interesting group for studying the evolution of mutualisms and immunity, for despite their morphological simplicity, Anthozoans are unexpectedly immunologically complex, with large genomes and gene families similar to those of the Bilateria. Evidence indicates that the Anthozoan innate immune system is not only involved in the disruption of harmful microorganisms, but is also crucial in structuring tissue-associated microbial communities that are essential components of the cnidarian holobiont and useful to the animal's health for several functions including metabolism, immune defense, development, and behavior. Here, we report on the current state of the art of Anthozoan immunity. Like other invertebrates, Anthozoans possess immune mechanisms based on self/non-self-recognition. Although lacking adaptive immunity, they use a diverse repertoire of immune receptor signaling pathways (PRRs) to recognize a broad array of conserved microorganism-associated molecular patterns (MAMP). The intracellular signaling cascades lead to gene transcription up to endpoints of release of molecules that kill the pathogens, defend the self by maintaining homeostasis, and modulate the wound repair process. The cells play a fundamental role in immunity, as they display phagocytic activities and secrete mucus, which acts as a physicochemical barrier preventing or slowing down the proliferation of potential invaders. Finally, we describe the current state of knowledge of some immune effectors in Anthozoan species, including the potential role of toxins and the inflammatory response in the Mediterranean Anthozoan Anemonia viridis following injection of various foreign particles differing in type and dimensions, including pathogenetic bacteria.
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Affiliation(s)
- Maria Giovanna Parisi
- Department of Earth and Marine Sciences, University of Palermo, 90128 Palermo, Italy;
| | - Daniela Parrinello
- Department of Earth and Marine Sciences, University of Palermo, 90128 Palermo, Italy;
| | - Loredana Stabili
- Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy;
| | - Matteo Cammarata
- Department of Earth and Marine Sciences, University of Palermo, 90128 Palermo, Italy;
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Lu Z, Mathew S, Chen J, Hadziselimovic A, Palamuttam R, Hudson BG, Fässler R, Pozzi A, Sanders CR, Zent R. Implications of the differing roles of the β1 and β3 transmembrane and cytoplasmic domains for integrin function. eLife 2016; 5. [PMID: 27929375 PMCID: PMC5207772 DOI: 10.7554/elife.18633] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 12/07/2016] [Indexed: 12/26/2022] Open
Abstract
Integrins are transmembrane receptors composed of α and β subunits. Although most integrins contain β1, canonical activation mechanisms are based on studies of the platelet integrin, αIIbβ3. Its inactive conformation is characterized by the association of the αIIb transmembrane and cytosolic domain (TM/CT) with a tilted β3 TM/CT that leads to activation when disrupted. We show significant structural differences between β1 and β3 TM/CT in bicelles. Moreover, the 'snorkeling' lysine at the TM/CT interface of β subunits, previously proposed to regulate αIIbβ3 activation by ion pairing with nearby lipids, plays opposite roles in β1 and β3 integrin function and in neither case is responsible for TM tilt. A range of affinities from almost no interaction to the relatively high avidity that characterizes αIIbβ3 is seen between various α subunits and β1 TM/CTs. The αIIbβ3-based canonical model for the roles of the TM/CT in integrin activation and function clearly does not extend to all mammalian integrins.
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Affiliation(s)
- Zhenwei Lu
- Department of Biochemistry, Vanderbilt University Medical Center, Nashville, United States
| | - Sijo Mathew
- Division of Nephrology, Department of Medicine, Vanderbilt Medical Center, Nashville, United States
| | - Jiang Chen
- Department of Biochemistry, Vanderbilt University Medical Center, Nashville, United States
| | - Arina Hadziselimovic
- Department of Biochemistry, Vanderbilt University Medical Center, Nashville, United States
| | - Riya Palamuttam
- Department of Biochemistry, Vanderbilt University Medical Center, Nashville, United States
| | - Billy G Hudson
- Department of Biochemistry, Vanderbilt University Medical Center, Nashville, United States.,Division of Nephrology, Department of Medicine, Vanderbilt Medical Center, Nashville, United States.,Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, United States.,Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, United States
| | - Reinhard Fässler
- Department of Molecular Medicine, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Ambra Pozzi
- Division of Nephrology, Department of Medicine, Vanderbilt Medical Center, Nashville, United States.,Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, United States.,Veterans Affairs Hospital, Nashville, United States.,Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, United States
| | - Charles R Sanders
- Department of Biochemistry, Vanderbilt University Medical Center, Nashville, United States
| | - Roy Zent
- Division of Nephrology, Department of Medicine, Vanderbilt Medical Center, Nashville, United States.,Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, United States.,Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, United States.,Veterans Affairs Hospital, Nashville, United States
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4
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Bai H, Li H, Li W, Gui T, Yang J, Cao D, Shen K. The PI3K/AKT/mTOR pathway is a potential predictor of distinct invasive and migratory capacities in human ovarian cancer cell lines. Oncotarget 2016; 6:25520-32. [PMID: 26267321 PMCID: PMC4694849 DOI: 10.18632/oncotarget.4550] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 07/04/2015] [Indexed: 12/21/2022] Open
Abstract
Objectives To explore the genetic and molecular events that control subclones exhibiting distinct invasive/migratory capacities derived from human epithelial ovarian cancer (EOC) cell line A2780 and SKOV3. Methods Single-cell subclones were isolated and established that were derived from the SKOV3 and A2780 cell lines through limiting dilution methodology. Transwell insert assays and MTT assays were performed to screen and identify the subclones exhibiting the highest and the lowest invasive/migratory capacities, and the selected subclones were renamed as A-H (A2780 high), A-L (A2780 low), S-H (SKOV3 high), and S-L (SKOV3 low). Their biological characteristics were evaluated. RNA-Seq was conducted on the targeted subclones. Results Compared with their corresponding counterparts, A-H/S-H cells exhibited significantly higher invasive/migratory capacities (P < 0.001 and = 0.001, respectively). A-H/S-H cells displayed a clear reduction in doubling time (P = 0.004 and 0.001, respectively), and a significant increase in the percentage of cells in S phase (P = 0.004 and 0.022, respectively). Additionally, the apoptotic rates of A-H/S-H cells were significantly lower than those of A-L/S-L cells (P = 0.002 and 0.026, respectively). At both mRNA and protein levels, caspase-3 and caspase-7 expression were reduced but Bcl-2 expression was increased in A-H/S-H cells. The TrkB (anoikis-related) and Beclin1 (autophagy-related) levels were consistently high and low, respectively, in both A-H/S-H cells. Resistance to chemotherapy in vitro and higher capacities on tumor formation in vivo was presented in both A-H/S-H cells. PI3K/AKT/mTOR pathway components, PIK3CA, PIK3CD, AKT3, ECM1, GPCR, mTOR and PRKCB were increased but that the Nur77 and PTEN were decreased in A-H/S-H cells, identified by RNA-Seq and consistently confirmed by RT-PCR and Western blot analyses. Conclusions Heterogeneous cell subpopulations exhibiting distinct invasive and migratory capacities co-exist within the SKOV3 and A2780 cell lines. PI3K/AKT/mTOR pathway activation is associated with higher invasive and migratory capacities in subpopulations of human ovarian cancer cell lines. Inhibiting this pathway may be useful for the chemoprevention or treatment of EOC.
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Affiliation(s)
- Huimin Bai
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing China.,Department of Obstetrics and Gynecology, Beijing Chao-Yang Hospital, China Capital Medical University, Beijing China
| | - Haixia Li
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing China
| | - Weihua Li
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing China
| | - Ting Gui
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing China
| | - Jiaxin Yang
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing China
| | - Dongyan Cao
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing China
| | - Keng Shen
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing China
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5
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Morandi EM, Verstappen R, Zwierzina ME, Geley S, Pierer G, Ploner C. ITGAV and ITGA5 diversely regulate proliferation and adipogenic differentiation of human adipose derived stem cells. Sci Rep 2016; 6:28889. [PMID: 27363302 PMCID: PMC4929468 DOI: 10.1038/srep28889] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 06/09/2016] [Indexed: 12/19/2022] Open
Abstract
The fate of human adipose tissue stem cells (ASCs) is largely determined by biochemical and mechanical cues from the extracellular matrix (ECM), which are sensed and transmitted by integrins. It is well known that specific ECM constituents influence ASC proliferation and differentiation. Nevertheless, knowledge on how individual integrins regulate distinct processes is still limited. We performed gene profiling of 18 alpha integrins in sorted ASCs and adipocytes, identifying downregulations of RGD-motif binding integrins integrin-alpha-V (ITGAV) and integrin-alpha-5 (ITGA5), upregulation of laminin binding and leukocyte-specific integrins and individual regulations of collagen and LDV-receptors in differentiated adipocytes in-vivo. Gene function analyses in in-vitro cultured ASCs unraveled differential functions of ITGA5 and ITGAV. Knockdown of ITGAV, but not ITGA5 reduced proliferation, caused p21Cip1 induction, repression of survivin and specific regulation of Hippo pathway mediator TAZ. Gene knockdown of both integrins promoted adipogenic differentiation, while transgenic expression impaired adipogenesis. Inhibition of ITGAV using cilengitide resulted in a similar phenotype, mimicking loss of pan-ITGAV expression using RNAi. Herein we show ASC specific integrin expression patterns and demonstrate distinct regulating roles of both integrins in human ASCs and adipocyte physiology suggesting a negative impact of RDG-motif signaling on adipogenic differentiation of ASCs via ITGA5 and ITGAV.
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Affiliation(s)
- E M Morandi
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria
| | - R Verstappen
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria
| | - M E Zwierzina
- Department of Anatomy, Histology and Embryology, Medical University of Innsbruck, Müllerstrasse 59, 6020 Innsbruck, Austria
| | - S Geley
- Division of Molecular Pathophysiology, Medical University of Innsbruck, Innrain 80, 6020 Innsbruck, Austria
| | - G Pierer
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria
| | - C Ploner
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria
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6
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CW-EPR studies revealed different motional properties and oligomeric states of the integrin β1a transmembrane domain in detergent micelles or liposomes. Sci Rep 2015; 5:7848. [PMID: 25597475 PMCID: PMC4297981 DOI: 10.1038/srep07848] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 12/16/2014] [Indexed: 12/15/2022] Open
Abstract
Integrins are heterodimeric membrane proteins that regulate essential processes: cell migration, cell growth, extracellular matrix assembly and tumor metastasis. Each integrin α or β subunit contains a large extracellular domain, a single transmembrane (TM) domain, and a short cytoplasmic tail. The integrin TM domains are important for heterodimeric association and dissociation during the conversion from inactive to active states. Moreover, integrin clustering occurs by homo-oligomeric interactions between the TM helices. Here, the transmembrane and cytoplasmic (TMC) domains of integrin β1a were overexpressed, and the protein was purified in detergent micelles and/or reconstituted in liposomes. To investigate the TM domain conformational properties of integrin β1a, 26 consecutive single cysteine mutants were generated for site-directed spin labeling and continuous-wave electron paramagnetic resonance (CW-EPR) mobility and accessibility analyses. The mobility analysis identified two integrin β1a-TM regions with different motional properties in micelles and a non-continuous integrin β1a-TM helix with high immobility in liposomes. The accessibility analysis verified the TM range (Val737-Lys752) of the integrin β1a-TMC in micelles. Further mobility and accessibility comparisons of the integrin β1a-TMC domains in micelles or liposomes identified distinctively different oligomeric states of integrin β1a-TM, namely a monomer embedded in detergent micelles and leucine-zipper-like homo-oligomeric clusters in liposomes.
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7
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8
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Martens-de Kemp SR, Brink A, Stigter-van Walsum M, Damen JMA, Rustenburg F, Wu T, van Wieringen WN, Schuurhuis GJ, Braakhuis BJ, Slijper M, Brakenhoff RH. CD98 marks a subpopulation of head and neck squamous cell carcinoma cells with stem cell properties. Stem Cell Res 2013; 10:477-88. [DOI: 10.1016/j.scr.2013.02.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 01/04/2013] [Accepted: 02/07/2013] [Indexed: 11/16/2022] Open
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9
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Spassov DS, Wong CH, Wong SY, Reiter JF, Moasser MM. Trask loss enhances tumorigenic growth by liberating integrin signaling and growth factor receptor cross-talk in unanchored cells. Cancer Res 2012; 73:1168-79. [PMID: 23243018 DOI: 10.1158/0008-5472.can-12-2496] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The cell surface glycoprotein Trask/CDCP1 is phosphorylated during anchorage loss in epithelial cells in which it inhibits integrin clustering, outside-in signaling, and cell adhesion. Its role in cancer has been difficult to understand, because of the lack of a discernible pattern in its various alterations in cancer cells. To address this issue, we generated mice lacking Trask function. Mammary tumors driven by the PyMT oncogene and skin tumors driven by the SmoM2 oncogene arose with accelerated kinetics in Trask-deficient mice, establishing a tumor suppressing function for this gene. Mechanistic investigations in mammary tumor cell lines derived from wild-type or Trask-deficient mice revealed a derepression of integrin signaling and an enhancement of integrin-growth factor receptor cross-talk, specifically in unanchored cell states. A similar restrictive link between anchorage and growth in untransformed epithelial cells was observed and disrupted by elimination of Trask. Together our results establish a tumor-suppressing function in Trask that restricts epithelial cell growth to the anchored state.
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Affiliation(s)
- Danislav S Spassov
- Department of Medicine, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA
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10
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Pan Y, Zhang K, Qi J, Yue J, Springer TA, Chen J. Cation-pi interaction regulates ligand-binding affinity and signaling of integrin alpha4beta7. Proc Natl Acad Sci U S A 2010; 107:21388-93. [PMID: 21098296 PMCID: PMC3003088 DOI: 10.1073/pnas.1015487107] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Integrin α(4)β(7) mediates rolling and firm adhesion of leucocytes, two of the critical steps in leukocyte migration and tissue specific homing. Affinity of α(4)β(7) for ligand is dynamically regulated by three interlinked metal ion-binding sites in β(7)-subunit I domain. In this study, we found that Phe185 (F185), a highly conserved aromatic residue in β(7)-subunit, links the specificity-determining loop and the synergistic metal ion-binding site (SyMBS) through cation-π interaction. Mutations of F185 that disrupted the SyMBS cation-F185 interaction led to deficient firm cell adhesion mediated by high affinity α(4)β(7), and only slightly affected rolling adhesion mediated by low affinity α(4)β(7). Disruption of SyMBS cation-F185 interaction induced partial extension of integrin ectodomain and separation of cytoplasmic tails, and impaired α(4)β(7)-mediated bidirectional signaling. In addition, loss of SyMBS cation-F185 interaction increased paxillin expression and promoted paxillin-integrin binding, leading to deficient cell spreading. Furthermore, integrin α(4)β(7)-mediated cell migration was decreased by the abolishment of SyMBS cation-F185 interaction. Thus, these findings reveal a cation-π interaction playing vital roles in the regulation of integrin affinity, signaling, and biological functions.
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Affiliation(s)
- YouDong Pan
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; and
| | - Kun Zhang
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; and
| | - JunPeng Qi
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; and
| | - Jiao Yue
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; and
| | - Timothy A. Springer
- The Immune Disease Institute, Children’s Hospital Boston, and Department of Pathology, Harvard Medical School, 3 Blackfan Circle, Boston, MA 02115
| | - JianFeng Chen
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; and
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11
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Skalski M, Sharma N, Williams K, Kruspe A, Coppolino MG. SNARE-mediated membrane traffic is required for focal adhesion kinase signaling and Src-regulated focal adhesion turnover. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:148-58. [PMID: 20888376 DOI: 10.1016/j.bbamcr.2010.09.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 09/10/2010] [Accepted: 09/15/2010] [Indexed: 01/27/2023]
Abstract
Integrin signaling is central to cell growth and differentiation, and critical for the processes of apoptosis, cell migration and wound repair. Previous research has demonstrated a requirement for SNARE-dependent membrane traffic in integrin trafficking, as well as cell adhesion and migration. The goal of the present research was to ascertain whether SNARE-dependent membrane trafficking is required specifically for integrin-mediated signaling. Membrane traffic was inhibited in Chinese hamster ovary cells by expression of dominant-negative (E329Q) N-ethylmaleimide-sensitive fusion protein (NSF) or a truncated form of the SNARE SNAP23. Integrin signaling was monitored as cells were plated on fibronectin under serum-free conditions. E329Q-NSF expression inhibited phosphorylation of focal adhesion kinase (FAK) on Tyr397 at early time points of adhesion. Phosphorylation of FAK on Tyr576, Tyr861 and Tyr925 was also impaired by expression of E329Q-NSF or truncated SNAP23, as was trafficking, localization and activation of Src and its interaction with FAK. Decreased FAK-Src interaction coincided with reduced Rac activation, decreased focal adhesion turnover, reduced Akt phosphorylation and lower phosphatidylinositol 3,4,5-trisphosphate levels in the cell periphery. Over-expression of plasma membrane-targeted Src or phosphatidylinositol 3-kinase (PI3K) rescued cell spreading and focal adhesion turnover. The results suggest that SNARE-dependent trafficking is required for integrin signaling through a FAK/Src/PI3K-dependent pathway.
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Affiliation(s)
- Michael Skalski
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
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12
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PI3-kinase p110α mediates β1 integrin-induced Akt activation and membrane protrusion during cell attachment and initial spreading. Cell Signal 2010; 22:1838-48. [PMID: 20667469 DOI: 10.1016/j.cellsig.2010.07.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Revised: 06/30/2010] [Accepted: 07/13/2010] [Indexed: 11/21/2022]
Abstract
Integrin-mediated cell adhesion activates several signaling effectors, including phosphatidylinositol 3-kinase (PI3K), a central mediator of cell motility and survival. To elucidate the molecular mechanisms of this important pathway the specific members of the PI3K family activated by different integrins have to be identified. Here, we studied the role of PI3K catalytic isoforms in β1 integrin-induced lamellipodium protrusion and activation of Akt in fibroblasts. Real-time total internal reflection fluorescence imaging of the membrane-substrate interface demonstrated that β1 integrin-mediated attachment induced rapid membrane spreading reaching essentially maximal contact area within 5-10 min. This process required actin polymerization and involved activation of PI3K. Isoform-selective pharmacological inhibition identified p110α as the PI3K catalytic isoform mediating both β1 integrin-induced cell spreading and Akt phosphorylation. A K756L mutation in the membrane-proximal part of the β1 integrin subunit, known to cause impaired Akt phosphorylation after integrin stimulation, induced slower cell spreading. The initial β1 integrin-regulated cell spreading as well as Akt phosphorylation were sensitive to the tyrosine kinase inhibitor PP2, but were not dependent on Src family kinases, FAK or EGF/PDGF receptor transactivation. Notably, cells expressing a Ras binding-deficient p110α mutant were severely defective in integrin-induced Akt phosphorylation, but exhibited identical membrane spreading kinetics as wild-type p110α cells. We conclude that p110α mediates β1 integrin-regulated activation of Akt and actin polymerization important for survival and lamellipodia dynamics. This could contribute to the tumorigenic properties of cells expressing constitutively active p110α.
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Abstract
Interactions between transmembrane (TM) helices play an important role in the regulation of diverse biological functions. For example, the TM helices of integrins are believed to interact heteromerically in the resting state; disruption of this interaction results in integrin activation and cellular adhesion. However, it has been difficult to demonstrate the specificity and affinity of the interaction between integrin TM helices and to relate them to the activation process. To examine integrin TM helix associations, we developed a bacterial reporter system and used it to define the sequence motif required for helix-helix interactions in the beta (1) and beta (3) integrin subfamilies. The helices interact in a novel three-dimensional motif, the "reciprocating large-small motif" that is also observed in the crystal structures of unrelated proteins. Modest but specific stabilization of helix associations is realized via packing of complementary small and large groups on neighboring helices. Mutations destabilizing this motif activate native, full-length integrins. Thus, this highly conserved dissociable motif plays a vital and widespread role as an on-off switch that can integrate with other control elements during integrin activation.
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14
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Su RJ, Li Z, Li HD, Song HJ, Cheng LF. Effects of hepatocyte growth factor on the expression and phosphorylation of focal adhesion kinase in SMMC-7721 cells. Shijie Huaren Xiaohua Zazhi 2009; 17:2070-2073. [DOI: 10.11569/wcjd.v17.i20.2070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effects of hepatocyte growth factor (HGF) on the expression and phosphorylation of focal adhesion kinase (FAK) and Src kinase, and explore the role of phosphatidylinositol 3-kinase (PI3K) in this process.
METHODS: After hepatocellular carcinoma cells (SMMC-7721) were pretreated with LY294002 and stimulated with HGF, the phosphorylation status of FAK at Y397 and Src at Y416 were analyzed by Western blot, and the distribution of FAK was observed by immunofluorescence.
RESULTS: HGF (50 μg/L) was able to promote the phosphorylation of FAK at Y397, but had no effect on the expression of FAK. Pretreatment of cells with LY294002 (an inhibitor of PI3K) significantly decreased the phosphorylation of FAK at Y397. After HGF treatment, FAK was mainly clustered in the periphery of hepatocellular carcinoma cells. In contrast, FAK was diffused throughout the cells after pretreatment with PI3K inhibitor. HGF treatment could significantly raise the phosphorylation levels of Src kinase and Src-Y416 while pretreatment with LY294002 could significantly decrease the phosphorylation levels of Src kinase and Src-Y416.
CONCLUSION: HGF is able to promote the activation of FAK and Src in a PI3K-dependent manner.
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Birge RB, Kalodimos C, Inagaki F, Tanaka S. Crk and CrkL adaptor proteins: networks for physiological and pathological signaling. Cell Commun Signal 2009; 7:13. [PMID: 19426560 PMCID: PMC2689226 DOI: 10.1186/1478-811x-7-13] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Accepted: 05/10/2009] [Indexed: 01/24/2023] Open
Abstract
The Crk adaptor proteins (Crk and CrkL) constitute an integral part of a network of essential signal transduction pathways in humans and other organisms that act as major convergence points in tyrosine kinase signaling. Crk proteins integrate signals from a wide variety of sources, including growth factors, extracellular matrix molecules, bacterial pathogens, and apoptotic cells. Mounting evidence indicates that dysregulation of Crk proteins is associated with human diseases, including cancer and susceptibility to pathogen infections. Recent structural work has identified new and unusual insights into the regulation of Crk proteins, providing a rationale for how Crk can sense diverse signals and produce a myriad of biological responses.
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Affiliation(s)
- Raymond B Birge
- Department of Biochemistry & Molecular Biology, UMDNJ-New Jersey Medical School, 185 South Orange Ave, Newark, NJ 07103, USA.
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16
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Abstract
The multicellular nature of metazoans means that all cellular processes need to be tuned by adhesive interactions between cells and their local microenvironment. The spatial organization of cells within tissues requires sophisticated networks of extracellular signals to control their survival and proliferation, movements and positioning, and differentiated function. These cellular characteristics are mediated by multiple inputs from adhesion systems in combination with soluble and developmental signals. In the present review we explore how one class of adhesion receptor, the integrins, co-operate with other types of receptor to control diverse aspects of cell fate. In particular we discuss: (i) how beta3 and beta1 integrins work together with growth factors to control angiogenesis; (ii) how alpha6beta4 integrin co-operates with receptor tyrosine kinases in normal epithelial function and cancer; (iii) the interplay between beta1 integrins and EGF (epidermal growth factor) receptor; (iv) signal integration connecting integrins and cytokine receptors for interleukins, prolactin and interferons; and (v) how integrins and syndecans co-operate in cell migration.
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17
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Abstract
The multicellular nature of metazoans means that all cellular processes need to be tuned by adhesive interactions between cells and their local microenvironment. The spatial organization of cells within tissues requires sophisticated networks of extracellular signals to control their survival and proliferation, movements and positioning, and differentiated function. These cellular characteristics are mediated by multiple inputs from adhesion systems in combination with soluble and developmental signals. In the present review we explore how one class of adhesion receptor, the integrins, co-operate with other types of receptor to control diverse aspects of cell fate. In particular we discuss: (i) how β3 and β1 integrins work together with growth factors to control angiogenesis; (ii) how α6β4 integrin co-operates with receptor tyrosine kinases in normal epithelial function and cancer; (iii) the interplay between β1 integrins and EGF (epidermal growth factor) receptor; (iv) signal integration connecting integrins and cytokine receptors for interleukins, prolactin and interferons; and (v) how integrins and syndecans co-operate in cell migration.
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Receptor for advanced glycation end-products (RAGE) modulates neutrophil adhesion and migration on glycoxidated extracellular matrix. Biochem J 2008; 416:255-61. [PMID: 18643777 DOI: 10.1042/bj20080054] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
AGEs (advanced glycation end-products) accumulate in collagen molecules during uraemia and diabetes, two diseases associated with high susceptibility to bacterial infection. Because neutrophils bind to collagen during their locomotion in extravascular tissue towards the infected area we investigated whether glycoxidation of collagen (AGE-collagen) alters neutrophil migration. Type I collagen extracted from rat tail tendons was used for in vitro glycoxidation (AGE-collagen). Neutrophils were obtained from peripheral blood of healthy adult volunteers and were used for the in vitro study of adhesion and migration on AGE- or control collagen. Glycoxidation of collagen increased adhesion of neutrophils to collagen surfaces. Neutrophil adhesion to AGE-collagen was inhibited by a rabbit anti-RAGE (receptor for AGEs) antibody and by PI3K (phosphoinositide 3-kinase) inhibitors. No effect was observed with ERK (extracellular-signal-regulated kinase) or p38 MAPK (mitogen-activated protein kinase) inhibitors. AGE-collagen was able to: (i) induce PI3K activation in neutrophils, and (ii) inhibit chemotaxis and chemokinesis of chemoattractant-stimulated neutrophils. Finally, we found that blocking RAGE with anti-RAGE antibodies or inhibiting PI3K with PI3K inhibitors restored fMLP (N-formylmethionyl-leucyl-phenylalanine)-induced neutrophil migration on AGE-collagen. These results show that RAGE and PI3K modulate adhesion and migration rate of neutrophils on AGE-collagen. Modulation of adhesiveness may account for the change in neutrophil migration rate on AGE-collagen. As neutrophils rely on their ability to move to perform their function as the first line of defence against bacterial invasion, glycoxidation of collagen may participate in the suppression of normal host defence in patients with diabetes and uraemia.
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Extended interaction of beta1 integrin subunit-deficient cells (GD25) with surfaces modified with fibronectin-derived peptides: Culture optimization, adhesion and cytokine panel studies. Acta Biomater 2008; 4:1172-86. [PMID: 18514047 DOI: 10.1016/j.actbio.2008.03.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 03/05/2008] [Accepted: 03/20/2008] [Indexed: 01/15/2023]
Abstract
The modification of biomaterials with extracellular matrix-mimicking factors is a common technique used to influence the cellular response through integrin-mediated signaling. The inherent limitations of antibody-inhibition studies necessitate the use of complementary methods to block integrin function to confirm cell-surface interaction. In this study, we employed a beta1 integrin-deficient cell line, GD25, to investigate the role of beta1 subunit in cell adhesion and subsequent cytokine (granulocyte macrophage colony stimulating factor; interleukin (IL)-1alpha; IL-1beta; IL-6; monocyte chemoattractant protein-1; regulated upon activation, normal T-cell expressed, and secreted; tumor necrosis factor-alpha) release kinetics in the presence of tissue culture polystyrene (TCPS) and semi-interpenetrating polymer networks (sIPN) modified with fibronectin (FN)-mimic peptides (RGD, PHSRN). Culture conditions (i.e. seeding density, medium, serum supplementation) were optimized for long-term observation. Differences in cell adhesion, cell viability and cytokine release behavior were dependent on the presence of the beta1 integrin subunit, FN, sIPN cast method and peptide identity. By comparing two complementary techniques for assaying integrin function, we observed both similarities (i.e. decreased adhesion to FN-absorbed TCPS and increased IL-1beta release at 96h) and differences (i.e. no difference in adhesion or IL-1beta release in the presence of different sIPN surfaces) when the function of the beta1 subunit was blocked in cell adhesion and signaling in the presence of biomaterials.
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20
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Sanders MA, Basson MD. Collagen IV regulates Caco-2 cell spreading and p130Cas phosphorylation by FAK-dependent and FAK-independent pathways. Biol Chem 2008; 389:47-55. [PMID: 18095869 DOI: 10.1515/bc.2008.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We previously observed that collagen IV regulates Caco-2 intestinal epithelial cell spreading and migration via Src-dependent p130(Cas) phosphorylation and stimulates focal adhesion kinase (FAK). However, the role of FAK and the related kinase, Pyk2, in Caco-2 spreading and migration is unclear. FAK- or Pyk2-specific siRNAs reduced protein levels by 90%. However, when detached cells were replated on collagen IV neither individual nor combined FAK and Pyk2 siRNAs affected the cell spreading rate. As combined FAK and Pyk2 siRNAs increased p130(Cas) protein levels, we cotransfected cells with 1 nm p130(Cas) siRNA to partially reduce p130(Cas) protein to control levels. Although p130(Cas) Tyr(P)(249) phosphorylation was reduced by 60%, cell spreading was unaffected. Combined siRNA reduction of FAK, Pyk2 and p130(Cas) increased cell spreading by 20% compared to p130(Cas) siRNA alone, suggesting that FAK and Pyk2 negatively regulate spreading in addition to stimulating spreading via p130(Cas). FAK-binding mutant SH3 domain-deleted rat p130(Cas) was not phosphorylated after adhesion and, unlike full-length p130(Cas), did not restore spreading after human-specific p130(Cas) siRNA knockdown of endogenous p130(Cas). Together, these data suggest that FAK positively regulates Caco-2 spreading on collagen IV via p130(Cas) phosphorylation, but also suggests that FAK may negatively regulate spreading through other mechanisms and the presence of additional FAK-independent pathways regulating p130(Cas).
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Affiliation(s)
- Matthew A Sanders
- Department of Surgery, Wayne State University, Detroit, MI 48201, USA.
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21
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Velling T, Stefansson A, Johansson S. EGFR and beta1 integrins utilize different signaling pathways to activate Akt. Exp Cell Res 2007; 314:309-16. [PMID: 17910952 DOI: 10.1016/j.yexcr.2007.08.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Revised: 08/23/2007] [Accepted: 08/23/2007] [Indexed: 02/07/2023]
Abstract
Akt, also called PKB, is a serine/threonine kinase that plays a major role in cell survival. It can be activated by several cellular receptors, including integrins and growth factor receptors, in PI3K-dependent manners. In this study, we analyzed the two current models for Akt activation upon beta1 integrin-mediated adhesion: via focal adhesion kinase and via transactivation of the EGF receptor. Distinct differences in the pathways leading to phosphorylation and activation of Akt from stimulated beta1 integrins and EGF receptor were observed, including opposing sensitivity to the tyrosine kinase inhibitors PP2 and Gefitinib. Using knockout cells and integrin mutant cells, we show that beta1 integrins can induce phosphorylation of Akt at Ser473 and Thr308 and Akt kinase activity independently of the EGF receptor activity, focal adhesion kinase, and the Src family members. In contrast to stimulation with EGF, beta1 integrin-mediated adhesion did not induce Akt tyrosine phosphorylation. Moreover, tyrosine phosphorylation of Akt was found not to be required for its catalytic activity. The results identify a previously unrecognized mechanism by which beta1 integrins activate the PI3K/Akt pathway.
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Affiliation(s)
- Teet Velling
- Department of Medical Sciences, University Hospital, 75185, Uppsala, Sweden.
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22
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Wang L, Tabu K, Kimura T, Tsuda M, Linghu H, Tanino M, Kaneko S, Nishihara H, Tanaka S. Signaling adaptor protein Crk is indispensable for malignant feature of glioblastoma cell line KMG4. Biochem Biophys Res Commun 2007; 362:976-81. [PMID: 17825249 DOI: 10.1016/j.bbrc.2007.08.106] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Accepted: 08/16/2007] [Indexed: 10/22/2022]
Abstract
Signaling adaptor protein Crk has been shown to be involved in pathogenesis of human cancers including brain tumor where Crk was reported to be overexpressed. In this study, we addressed whether Crk is indispensable for malignant phenotype of brain tumor. In 20 surgical specimens of glioma, mRNA of both CrkI and CrkII was found to be elevated in malignant tumor. To define a precise role of Crk, we have established Crk-knockdown cell lines of glioblastoma KMG4 by siRNA, and early phase of cell adhesion to laminin was found to be suppressed. Wound healing assay revealed the decreased cell motility in Crk knockdown cells, and suppression of both anchorage-dependent and -independent growth were demonstrated in these cells. Furthermore, in vivo tumor forming potential was also markedly suppressed. These results suggest that Crk is required for early attachment to laminin, cell motility, and growth of glioblastoma cell line KMG4.
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Affiliation(s)
- Lei Wang
- Laboratory of Molecular and Cellular Pathology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan, and Department of Obstetrics & Gynecology, First Affiliated Hospital of Chongqing University of Medical Sciences, China
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23
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Mazza R, Mannarino C, Imbrogno S, Barbieri SF, Adamo C, Angelone T, Corti A, Tota B. Crucial role of cytoskeleton reorganization in the negative inotropic effect of chromogranin A-derived peptides in eel and frog hearts. ACTA ACUST UNITED AC 2007; 138:145-51. [PMID: 17056132 DOI: 10.1016/j.regpep.2006.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 09/11/2006] [Accepted: 09/12/2006] [Indexed: 10/24/2022]
Abstract
Vasostatins (VSs), i.e. the main biologically active peptides generated by the proteolytic processing of chromogranin A (CGA) N-terminus, exert negative inotropism in vertebrate hearts. Here, using isolated working eel (Anguilla anguilla) and frog (Rana esculenta) heart preparations, we have studied the role of the cytoskeleton in the VSs-mediated inotropic response. In both eel and frog hearts, VSs-mediated-negative inotropy was abolished by treatment with inhibitors of cytoskeleton reorganization, such as cytochalasin-D (eel: 10 nM; frog: 1 nM), an inhibitor of actin polymerisation, wortmannin (0.01 nM), an inhibitor of PI3-kinase (PI3-K)/protein kinase B (Akt) signal-transduction cascade, butanedione 2-monoxime (BDM) (eel: 100 nM; frog: 10 nM), an antagonist of myosin ATPase, and N-(6-aminohexil)-5-chloro-1-naphthalenesulfonamide (W7) (eel: 100 nM; frog: 1 nM), a calcium-calmodulin antagonist. These results demonstrate that changes in cytoskeletal dynamics play a crucial role in the negative inotropic influence of VSs on eel and frog hearts.
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Affiliation(s)
- Rosa Mazza
- Department of Cell Biology, University of Calabria, 87030 Arcavacata di Rende (CS), Italy.
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Plows LD, Cook RT, Davies AJ, Walker AJ. Integrin engagement modulates the phosphorylation of focal adhesion kinase, phagocytosis, and cell spreading in molluscan defence cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:779-86. [PMID: 16766054 DOI: 10.1016/j.bbamcr.2006.04.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Revised: 04/07/2006] [Accepted: 04/07/2006] [Indexed: 12/21/2022]
Abstract
Integrins play a key role in cellular immune responses in a variety of organisms; however, knowledge of integrins and their effects on cell signalling and functional responses in molluscan defence reactions is poor. Using integrin-mediated cell adhesion kits, alphaVbeta3 and beta1 integrin-like subunits were identified on the surface of Lymnaea stagnalis haemocytes. Haemocyte binding via these integrins was found to be dependent on Ca2+/Mg2+. Western blotting with an anti-phospho (anti-active) focal adhesion kinase (FAK) antibody revealed a 120-125 kDa FAK-like protein in these cells; this protein was transiently phosphorylated upon haemocyte adhesion over 90 min, with maximal phosphorylation occurring after 30 min binding. Also, integrin engagement with the tetrapeptide Arg-Gly-Asp-Ser (RGDS) resulted in a rapid increase in phosphorylation of the FAK-like protein; however, RGDS did not affect the phosphorylation of extracellular signal-regulated kinase. Treatment of haemocytes with RGDS (2 mM) inhibited phagocytosis of E. coli bioparticles by 88%. Moreover, at this concentration, RGDS reduced cell spreading by 61%; stress fiber formation was also impaired. Taken together, these results demonstrate a role for integrins in L. stagnalis haemocyte adhesion and defence reactions and, for the first time, link integrin engagement to FAK activation in molluscs.
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Affiliation(s)
- Louise D Plows
- School of Life Sciences, Kingston University, Penrhyn Road, Kingston-upon-Thames, Surrey, KT1 2EE, UK
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25
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Laplante P, Raymond MA, Labelle A, Abe JI, Iozzo RV, Hébert MJ. Perlecan proteolysis induces an alpha2beta1 integrin- and Src family kinase-dependent anti-apoptotic pathway in fibroblasts in the absence of focal adhesion kinase activation. J Biol Chem 2006; 281:30383-92. [PMID: 16882656 DOI: 10.1074/jbc.m606412200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Dysregulation of apoptosis in endothelial cells (EC) and fibroblasts contributes to fibrosis. We have shown previously that apoptosis of EC triggers the proteolysis of extracellular matrix components and the release of a C-terminal fragment of perlecan, which in turn inhibits apoptosis of fibroblasts. Here we have defined the receptors and pathways implicated in this anti-apoptotic response in fibroblasts. Neutralizing alpha2beta1 integrin activity in fibroblasts exposed to either medium conditioned by apoptotic EC (SSC) or a recombinant perlecan C-terminal fragment (LG3) prevented resistance to apoptosis and is associated with decreased levels of Akt phosphorylation. Co-incubation of fibroblasts for 24 h with SSC or LG3 in the presence of PP2 (AG1879), a biochemical inhibitor of Src family kinases (SFKs) and focal adhesion kinase, showed a significantly decreased anti-apoptotic response. However, focal adhesion kinase gene silencing with RNA interference did not inhibit the anti-apoptotic response in fibroblasts. Src phosphorylation was increased in fibroblasts exposed to SSC, and transfection of fibroblasts with constitutively active Src mutants induced an anti-apoptotic response that was not further increased by SSC. Also, Src(-/-)Fyn(-/-) fibroblasts failed to mount an anti-apoptotic response in presence of SSC for 24 h but developed a complete anti-apoptotic response when exposed to SSC for 7 days. These results suggest that extracellular matrix fragments produced by apoptotic EC initiate a state of resistance to apoptosis in fibroblasts via an alpha2beta1 integrin/SFK (Src and Fyn)/phosphatidylinositol 3-kinase (PI3K)-dependent pathway. In the long term, additional SFK members are recruited for sustaining the anti-apoptotic response, which could play crucial roles in abnormal fibrogenic healing.
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Affiliation(s)
- Patrick Laplante
- Centre de Recherche du Centre Hospitalier de l'Université de Montreal, University of Montreal, 1560 Sherbrooke East, Montreal, Quebec H2L 4M1, Canada
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Efron PA, Chen MK, Iyengar M, Dai W, Nagaram A, Beierle EA. Differential response of neuroblastoma cells to TRAIL is independent of PI3K/AKT. J Pediatr Surg 2006; 41:1072-80. [PMID: 16769337 DOI: 10.1016/j.jpedsurg.2006.02.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND In many human tumor cells, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis through caspase activation, whereas activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway prevents apoptosis. We hypothesized that inhibition of PI3K/Akt would increase TRAIL-induced apoptosis in neuroblastoma cells. METHODS SK-N-AS, SH-SY5Y, and IMR-32 neuroblastoma cells were cultured with either standard media or media with PI3K/Akt inhibitor for 24 hours. These cells were then exposed to 100 ng/mL of TRAIL for 90 minutes and harvested. Cells either underwent flow cytometric analysis of apoptosis, had protein extracted for Western blot, had RNA extracted for reverse transcription-polymerase chain reaction, or had cell lysates analyzed for caspase-3, -8, and -9. RESULTS Baseline expression of TRAIL receptors and Akt varied among the cell lines. Inhibition of PI3K/Akt decreased caspase-3 activation in the AS and SY cells, but did not alter TRAIL-induced apoptosis in any of the cell lines. Activity of caspase-8 and -9 was also unaffected by PI3K/Akt attenuation. CONCLUSIONS Inhibition of the PI3K/Akt pathway does not increase the sensitivity of neuroblastoma cell lines to TRAIL-induced apoptosis. Neuroblastoma is unique in that activation of the PI3K/Akt pathway is either not essential to its TRAIL resistance or counteracted because of the multiple repetitive pathways of TRAIL resistance.
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Affiliation(s)
- Philip A Efron
- Division of Pediatric Surgery, Department of Surgery, University of Florida College of Medicine, Box 100286, JHMHSC, Gainesville, FL 32610-0286, USA
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27
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Greenberg RS, Bernstein AM, Benezra M, Gelman IH, Taliana L, Masur SK. FAK-dependent regulation of myofibroblast differentiation. FASEB J 2006; 20:1006-8. [PMID: 16585062 DOI: 10.1096/fj.05-4838fje] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Fibroblasts and myofibroblasts both participate in wound healing. Transforming growth factor beta (TGFbeta) induces fibroblasts to differentiate into myofibroblasts, whereas fibroblast growth factor and heparin (FGF/h) induce myofibroblasts to "de-differentiate" into fibroblasts. TGFbeta induces expression of smooth muscle alpha actin (SMalphaA) and incorporation into in stress fibers, a phenotype of differentiated myofibroblasts. Additionally, TGFbeta induces the expression of fibronectin and fibronectin integrins. Fibronectin-generated signals contribute to the TGFbeta-mediated myofibroblast differentiation. Because fibronectin signals are transmitted through focal adhesion kinase (FAK), it was predicted that FAK would be essential to TGFbeta-mediated myofibroblast differentiation. To determine whether the FAK signaling pathway is required for myofibroblast differentiation, we used two approaches to decrease FAK in mouse embryo fibroblasts (MEFs): 1) FAK +/+ MEFs, in which FAK protein expression was greatly decreased by short hairpin RNA (shRNA), and 2) FAK -/- MEFs, which lack FAK. In both cases, the majority of cells were myofibroblasts, expressing SMalphaA in stress fibers even after treatment with FGF/h. Furthermore, both the surface expression of FGFRs and FGF signaling were greatly reduced in FAK -/- [corrected]MEFs. We conclude that FAK does not contribute to TGFbeta-dependent myofibroblast differentiation. Instead, FAK was necessary for FGF/h signaling in down-regulating expression of SMalphaA, which is synonymous with myofibroblast differentiation. FAK activation could contribute to regulating myofibroblast differentiation, thereby ameliorating fibrosis.
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Affiliation(s)
- Roseanne S Greenberg
- Department of Ophthalmology, Box 1183, Mount Sinai School of Medicine, 1 Gustave Levy Pl., New York, New York 10029-6574, USA.
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28
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Chang JC, Chang HH, Lin CT, Lo SJ. The integrin alpha6beta1 modulation of PI3K and Cdc42 activities induces dynamic filopodium formation in human platelets. J Biomed Sci 2005; 12:881-98. [PMID: 16228294 DOI: 10.1007/s11373-005-9021-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Accepted: 08/03/2005] [Indexed: 11/28/2022] Open
Abstract
Platelets are an ideal model for studying a rapid morphological change in response to various signal transduction systems. Morphological changes via the activation of integrin alphaIIbbeta3 in platelets have been investigated intensively. In contrast, activation via integrin alpha6beta1 is less well studied. Here, we provide the first biochemical evidence that integrins alpha6beta1 and alphaIIbbeta3 of platelets are associated with different membrane proteins. We also demonstrate that platelets activated by integrin alpha6beta1 show dynamic change by actively forming filopodia and never fully spreading over a period of more than an hour. In addition, platelets activated by integrin alpha6beta1 are different from those activated by integrin alphaIIbbeta3 in terms of cell-substrate contact and in their distribution pattern of actin, Arp2/3 and various phosphotyrosine proteins. The morphological appearance of platelets produced through integrin alpha6beta1 activation is highly dependent on PI3 kinase (PI3K) but less dependent on Src kinase. Suppression of PI3K activity in integrin alpha6beta1 activated platelets induces an increase in Cdc42 activity and more filopodium formation. However, both Cdc42 and PI3K activity are higher in platelets activated by integrin alpha6beta1 than in those activated by integrin alphaIIbbeta3. Taken together, this study demonstrates that the signals induced by integrin alpha6beta1 modulate at the level of PI3K and Cdc42 activity to allow platelets to actively form filopodia.
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Affiliation(s)
- Jui-Chin Chang
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, 112, Taiwan
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29
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Thodeti CK, Fröhlich C, Nielsen CK, Holck P, Sundberg C, Kveiborg M, Mahalingam Y, Albrechtsen R, Couchman JR, Wewer UM. Hierarchy of ADAM12 binding to integrins in tumor cells. Exp Cell Res 2005; 309:438-50. [PMID: 16061220 DOI: 10.1016/j.yexcr.2005.06.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 06/29/2005] [Accepted: 06/30/2005] [Indexed: 11/19/2022]
Abstract
ADAMs (a disintegrin and metalloprotease) comprise a family of cell surface proteins with protease and cell-binding activities. Using different forms and fragments of ADAM12 as substrates in cell adhesion and spreading assays, we demonstrated that alpha9beta1 integrin is the main receptor for ADAM12. However, when alpha9beta1 integrin is not expressed--as in many carcinoma cells--other members of the beta1 integrin family can replace its ligand binding activity. In attachment assays, the recombinant disintegrin domain of ADAM12 only supported alpha9 integrin-dependent tumor cell attachment, whereas full-length ADAM12 supported attachment via alpha9 integrin and other integrin receptors. Cells that attached to full-length ADAM12 in an alpha9 integrin-dependent manner also attached to ADAM12 in which the putative alpha9beta1 integrin-binding motif in the disintegrin domain had been mutated. This attachment was mediated through use of an alternate beta1 integrin. We also found that cell spreading in response to ADAM12 is dependent on the apparent level of integrin activation. Binding of cells to ADAM12 via the alpha9beta1 integrin was Mn(2+)-independent and resulted in attachment of cells with a rounded morphology; attachment of cells with a spread morphology required further activation of the alpha9beta1 integrin. We demonstrated that phosphoinositide-3-kinase appears to be central in regulating alpha9beta1 integrin cell spreading activity in response to ADAM12.
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Affiliation(s)
- Charles Kumar Thodeti
- Institute of Molecular Pathology, University of Copenhagen, Frederik V's vej 11, DK-2100 Copenhagen, Denmark
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30
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Zhang J, Mruk DD, Cheng CY. Myotubularin phosphoinositide phosphatases, protein phosphatases, and kinases: their roles in junction dynamics and spermatogenesis. J Cell Physiol 2005; 204:470-83. [PMID: 15690393 DOI: 10.1002/jcp.20303] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Spermatogenesis in the seminiferous epithelium of the mammalian testis is a dynamic cellular event. It involves extensive restructuring at the Sertoli-germ cell interface, permitting germ cells to traverse the epithelium from basal to adluminal compartment. As such, Sertoli-germ cell actin-based adherens junctions (AJ), such as ectoplasmic specializations (ES), must disassemble and reassemble to facilitate this event. Recent studies have shown that AJ dynamics are regulated by intricate interactions between AJ integral membrane proteins (e.g., cadherins, alpha6beta1 integrins and nectins), phosphatases, kinases, adaptors, and the underlying cytoskeleton network. For instance, the myotubularin (MTM) phosphoinositide (PI) phosphatases, such as MTM related protein 2 (MTMR2), can form a functional complex with c-Src (a non-receptor protein tyrosine kinase). In turn, this phosphatase/kinase complex associates with beta-catenin, a constituent of the N-cadherin/beta-catenin functional unit at the AJ site. This MTMR2-c-Src-beta-catenin complex apparently regulates the phosphorylation status of beta-catenin, which determines cell adhesive function conferred by the cadherin-catenin protein complex in the seminiferous epithelium. In this review, we discuss the current status of research on selected phosphatases and kinases, and how these proteins potentially interact with adaptors at AJ in the seminiferous epithelium to regulate cell adhesion in the testis. Specific research areas that are open for further investigation are also highlighted.
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Affiliation(s)
- Jiayi Zhang
- Population Council, Center for Biomedical Research, New York, New York, USA
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31
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Short SM, Derrien A, Narsimhan RP, Lawler J, Ingber DE, Zetter BR. Inhibition of endothelial cell migration by thrombospondin-1 type-1 repeats is mediated by beta1 integrins. ACTA ACUST UNITED AC 2005; 168:643-53. [PMID: 15716381 PMCID: PMC2171765 DOI: 10.1083/jcb.200407060] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The anti-angiogenic effect of thrombospondin-1 has been shown to be mediated through binding of the type-1 repeat (TSR) domain to the CD36 transmembrane receptor. We now report that the TSR domain can inhibit VEGF-induced migration in human umbilical vein endothelial cells (HUVEC), cells that lack CD36. Moreover, we identified β1 integrins as a critical receptor in TSR-mediated inhibition of migration in HUVEC. Using pharmacological inhibitors of downstream VEGF receptor effectors, we found that phosphoinositide 3-kinase (PI3k) was essential for TSR-mediated inhibition of HUVEC migration, but that neither PLCγ nor Akt was necessary for this response. Furthermore, β1 integrins were critical for TSR-mediated inhibition of microvascular endothelial cells, cells that express CD36. Together, our results indicate that β1 integrins mediate the anti-migratory effects of TSR through a PI3k-dependent mechanism.
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Affiliation(s)
- Sarah M Short
- Vascular Biology Program, Children's Hospital, Boston, MA 02115, USA
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32
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Velling T, Nilsson S, Stefansson A, Johansson S. beta1-Integrins induce phosphorylation of Akt on serine 473 independently of focal adhesion kinase and Src family kinases. EMBO Rep 2005; 5:901-5. [PMID: 15309026 PMCID: PMC1299135 DOI: 10.1038/sj.embor.7400234] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Revised: 07/23/2004] [Accepted: 07/27/2004] [Indexed: 01/18/2023] Open
Abstract
Adhesion by means of beta1-integrins induces the phosphorylation of Akt, an event strictly dependent on the activity of the phosphatidylinositol 3-kinase (PI3K). Binding of the p85 regulatory subunit of PI3K to phosphorylated tyrosine 397 in focal adhesion kinase (FAK) is considered to be the mechanism of cell adhesion-induced activation of class Ia PI3K. Here we show that PI3K-dependent phosphorylation of Akt in response to ligation of beta1-integrins occurs efficiently in the absence of FAK tyrosine phosphorylation. Akt S473 phosphorylation was strongly promoted both in cells expressing the integrin subunit splice variant beta1B, which is unable to activate FAK, and in FAK knockout cells. In addition, we found this phosphorylation to be independent of the Src family kinases Src, Fyn and Yes. These results indicate that a major pathway for adhesion-dependent activation of PI3K/Akt is triggered by the membrane proximal part of the beta1 subunit in a FAK and Src-independent manner.
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Affiliation(s)
- Teet Velling
- Department of Medical Biochemistry and Microbiology, The Biomedical Center, Uppsala University, 75123 Uppsala, Sweden.
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Sarin V, Gaffin RD, Meininger GA, Muthuchamy M. Arginine-glycine-aspartic acid (RGD)-containing peptides inhibit the force production of mouse papillary muscle bundles via alpha 5 beta 1 integrin. J Physiol 2005; 564:603-17. [PMID: 15718258 PMCID: PMC1464440 DOI: 10.1113/jphysiol.2005.083238] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Integrins are considered to be an important mechanosensor in cardiac myocytes. To test whether integrins can influence cardiac contractile function, the force-frequency relationships of mouse papillary muscle bundles were measured in the presence or absence of a synthetic integrin-binding peptide, GRGDNP (gly-arg-gly-asp-asn-pro). Results demonstrate that in the presence of an arginine-glycine-aspartic acid (RGD)-containing synthetic peptide, contractile force was depressed significantly by, 28% at 4 Hz, 37.7% at 5 Hz and 20% at 10 Hz (n = 6, P < 0.01). Treatment of myofibres with either protease-generated fragments of denatured collagen (Type I) or denatured collagen that contain the RGD motif, also reduced force production significantly. An integrin-activating antibody for beta(1) integrin inhibited the force similar to synthetic RGD peptide. Function-blocking integrin antibodies for alpha(5) and beta(1) integrins reversed the effect of the RGD-containing peptide, and alpha(5) integrin also reversed the effect of proteolytic fragments of denatured collagen on contractile force, whereas experiments with function-blocking antibody for beta(3) integrin did not reverse the effect of RGD peptide. Force-[Ca(2)(+)](i) measurements showed that the depressed rate of force generation observed in the presence of the RGD-containing peptide was associated with reduced [Ca(2)(+)](i). Data analyses further demonstrated that force per unit of Ca(2)(+) was reduced, suggesting that the myofilament activation process was altered. In addition, inhibition of PKC enzyme using the selective, cell-permeable inhibitor Ro-32-0432, reversed the activity of RGD peptide on papillary muscle bundles. In conclusion, these data indicate that RGD peptide, acting via alpha(5)beta(1) integrin, depresses the force production from papillary muscle bundles, partly associated with changes in [Ca(2)(+)](i) and the myofilament activation processes, that is modulated by PKCepsilon.
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Affiliation(s)
- Vandana Sarin
- Department of Medical Physiology, Cardiovascular Research Institute, 336 Reynolds Medical Building, Texas A & M University System Health Science Center, College of Medicine, College Station, TX 77843-1114, USA
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Cai S, Bulus N, Fonseca-Siesser PM, Chen D, Hanks SK, Pozzi A, Zent R. CD98 modulates integrin beta1 function in polarized epithelial cells. J Cell Sci 2005; 118:889-99. [PMID: 15713750 DOI: 10.1242/jcs.01674] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type II transmembrane protein CD98, best known as the heavy chain of the heterodimeric amino acid transporters (HAT), is required for the surface expression and basolateral localization of this transporter complex in polarized epithelial cells. CD98 also interacts with beta1 integrins resulting in an increase in their affinity for ligand. In this study we explored the role of the transmembrane and cytoplasmic domains of CD98 on integrin-dependent cell adhesion and migration in polarized renal epithelial cells. We demonstrate that the transmembrane domain of CD98 was sufficient, whereas the five N-terminal amino acids of this domain were required for CD98 interactions with beta1 integrins. Overexpression of either full-length CD98 or CD98 lacking its cytoplasmic tail increased cell adhesion and migration, whereas deletion of the five N-terminal amino acids of the transmembrane domain of CD98 abrogated this effect. CD98 and mutants that interacted with beta1 integrins increased both focal adhesion formation and FAK and AKT phosphorylation. CD98-induced cell adhesion and migration was inhibited by addition of phosphoinositol 3-OH kinase (PI3-K) inhibitors suggesting these cell functions are PI3-K-dependent. Finally, CD98 and mutants that interacted with beta1, induced marked changes in polarized renal epithelial cell branching morphogenesis in collagen gels. Thus, in polarized renal epithelial cells, CD98 might be viewed as a scaffolding protein that interacts with basolaterally expressed amino acid transporters and beta1 integrins and can alter diverse cellular functions such as amino acid transport as well as cell adhesion, migration and branching morphogenesis.
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Affiliation(s)
- Songmin Cai
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN 37232, USA
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Zhou S, Schmelz A, Seufferlein T, Li Y, Zhao J, Bachem MG. Molecular Mechanisms of Low Intensity Pulsed Ultrasound in Human Skin Fibroblasts. J Biol Chem 2004; 279:54463-9. [PMID: 15485877 DOI: 10.1074/jbc.m404786200] [Citation(s) in RCA: 173] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Soluble factors such as polypeptide growth factors, mitogenic lipids, inflammatory cytokines, and hormones are known regulators of cell proliferation. However, the effect of mechanical stimuli on cell proliferation is less well understood. Here we examined the effect of low intensity pulsed ultrasound (US), which is used to promote wound healing, on the proliferation of primary human foreskin fibroblasts and the underlying signaling mechanisms. We show that a single 6-11-min US stimulation increases bromodeoxyuridine incorporation. In addition, an increase in the total cell number is observed after sequential US stimulation. US induced stress fiber and focal adhesion formation via activation of Rho. We further observed that US selectively induced activation of extracellular signal-regulated kinase (ERK) 1/2. Inhibition of Rho-associated coiled-coil-containing protein kinase (ROCK) prevented US-induced ERK1/2 activation, demonstrating that the Rho/ROCK pathway is an upstream regulator of ERK activation in response to US. Consequently, activation of ROCK and MEK-1 was required for US-induced DNA synthesis. Finally, an integrin beta(1) blocking antibody as well as a RGD peptide prevented US-induced DNA synthesis. In addition, US slightly increased phosphorylation of Src at Tyr(416), and Src activity was found to be required for ERK1/2 activation in response to US. In conclusion, our data demonstrate for the first time that US promotes cell proliferation via activation of integrin receptors and a Rho/ROCK/Src/ERK signaling pathway.
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Affiliation(s)
- Shaoxia Zhou
- Department of Clinical Chemistry, University of Ulm, D-89081 Ulm, Germany
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