101
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Lai C, Liu X, Tian C, Wu F. Integrin α1 has a long helix, extending from the transmembrane region to the cytoplasmic tail in detergent micelles. PLoS One 2013; 8:e62954. [PMID: 23646163 PMCID: PMC3639902 DOI: 10.1371/journal.pone.0062954] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 03/26/2013] [Indexed: 12/12/2022] Open
Abstract
Integrin proteins are very important adhesion receptors that mediate cell-cell and cell-extracellular matrix interactions. They play essential roles in cell signaling and the regulation of cellular shape, motility, and the cell cycle. Here, the transmembrane and cytoplasmic (TMC) domains of integrin α1 and β1 were over-expressed and purified in detergent micelles. The structure and backbone relaxations of α1-TMC in LDAO micelles were determined and analyzed using solution NMR. A long helix, extending from the transmembrane region to the cytoplasmic tail, was observed in α1-TMC. Structural comparisons of α1-TMC with reported αIIb-TMC domains indicated different conformations in the transmembrane regions and cytoplasmic tails. An NMR titration experiment indicated weak interactions between α1-TMC and β1-TMC through several α1-TMC residues located at its N-terminal juxta-transmembrane region and C-terminal extended helix region.
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Affiliation(s)
- Chaohua Lai
- Hefei National Laboratory for Physical Science at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Xiaoxi Liu
- Hefei National Laboratory for Physical Science at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Changlin Tian
- Hefei National Laboratory for Physical Science at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, China
- * E-mail: (CT); (FW)
| | - Fangming Wu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, China
- * E-mail: (CT); (FW)
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102
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Hart R, Stanley P, Chakravarty P, Hogg N. The kindlin 3 pleckstrin homology domain has an essential role in lymphocyte function-associated antigen 1 (LFA-1) integrin-mediated B cell adhesion and migration. J Biol Chem 2013; 288:14852-62. [PMID: 23595985 DOI: 10.1074/jbc.m112.434621] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The protein kindlin 3 is mutated in the leukocyte adhesion deficiency III (LAD-III) disorder, leading to widespread infection due to the failure of leukocytes to migrate into infected tissue sites. To gain understanding of how kindlin 3 controls leukocyte function, we have focused on its pleckstrin homology (PH) domain and find that deletion of this domain eliminates the ability of kindlin 3 to participate in adhesion and migration of B cells mediated by the leukocyte integrin lymphocyte function-associated antigen 1 (LFA-1). PH domains are often involved in membrane localization of proteins through binding to phosphoinositides. We show that the kindlin 3 PH domain has binding affinity for phosphoinositide PI(3,4,5)P3 over PI(4,5)P2. It has a major role in membrane association of kindlin 3 that is enhanced by the binding of LFA-1 to intercellular adhesion molecule 1 (ICAM-1). A splice variant, kindlin 3-IPRR, has a four-residue insert in the PH domain at a critical site that influences phosphoinositide binding by enhancing binding to PI(4,5)P2 as well as by binding to PI(3,4,5)P3. However kindlin 3-IPRR is unable to restore the ability of LAD-III B cells to adhere to and migrate on LFA-1 ligand ICAM-1, potentially by altering the dynamics or PI specificity of binding to the membrane. Thus, the correct functioning of the kindlin 3 PH domain is central to the role that kindlin 3 performs in guiding lymphocyte adhesion and motility behavior, which in turn is required for a successful immune response.
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Affiliation(s)
- Rosie Hart
- Leukocyte Adhesion Laboratory, Cancer Research United Kingdom London Research Institute, London WC2A 3LY, United Kingdom
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103
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Lee YC, Jin JK, Cheng CJ, Huang CF, Song JH, Huang M, Brown WS, Zhang S, Yu-Lee LY, Yeh ET, McIntyre BW, Logothetis CJ, Gallick GE, Lin SH. Targeting constitutively activated β1 integrins inhibits prostate cancer metastasis. Mol Cancer Res 2013; 11:405-17. [PMID: 23339185 PMCID: PMC3631285 DOI: 10.1158/1541-7786.mcr-12-0551] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Disseminated prostate cancer cells must survive in circulation for metastasis to occur. Mechanisms by which these cells survive are not well understood. By immunohistochemistry of human tissues, we found that levels of β1 integrins and integrin-induced autophosphorylation of FAK (pFAK-Y397) are increased in prostate cancer cells in primary prostate cancer and lymph node metastases, suggesting that β1 integrin activation occurs in metastatic progression of prostate cancer. A conformation-sensitive antibody, 9EG7, was used to examine β1 integrin activation. We found that β1 integrins are constitutively activated in highly metastatic PC3 and PC3-mm2 cells, with less activation in low metastatic LNCaP and C4-2B4 cells. Increased β1 integrin activation as well as the anoikis resistance in prostate cancer cells correlated with metastatic potential in vivo. Knockdown of β1 integrin abrogated anoikis resistance in PC3-mm2 cells. In agreement with β1 integrin activation, PC3-mm2 cells strongly adhered to type I collagen and fibronectin, a process inhibited by the β1 integrin-neutralizing antibody mAb 33B6. mAb 33B6 also inhibited the phosphorylation of β1 integrin downstream effectors, focal adhesion kinase (FAK) and AKT, leading to a 3-fold increase in PC3-mm2 apoptosis. Systemic delivery of mAb 33B6 suppressed spontaneous metastasis of PC3-mm2 from the prostate to distant lymph nodes following intraprostatic injection and suppressed metastasis of PC3-mm2 to multiple organs following intracardiac injection. Thus, constitutively activated β1 integrins play a role in survival of PC3-mm2 cells in circulation and represent a potential target for metastasis prevention.
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Affiliation(s)
- Yu-Chen Lee
- Department of Molecular Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Jung-Kang Jin
- Department of Genitourinary Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
- The Program in Cancer Metastasis, The University of Texas Graduate School of Biomedical Sciences at Houston
| | - Chien-Jui Cheng
- Department of Pathology, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Chih-Fen Huang
- Department of Molecular Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
- Department of Pharmacy at National Taiwan University Hospital, Taipei, Taiwan
| | - Jian H. Song
- Department of Genitourinary Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Miao Huang
- Department of Molecular Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Wells S. Brown
- Department of Immunology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Sui Zhang
- Department of Cardiology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Li-Yuan Yu-Lee
- Department of Medicine, Baylor College of Medicine, Houston, Texas 77030
| | - Edward T. Yeh
- Department of Cardiology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Bradley W. McIntyre
- Department of Immunology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Christopher J. Logothetis
- Department of Genitourinary Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Gary E. Gallick
- Department of Genitourinary Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
- The Program in Cancer Metastasis, The University of Texas Graduate School of Biomedical Sciences at Houston
| | - Sue-Hwa Lin
- Department of Molecular Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
- Department of Genitourinary Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
- The Program in Cancer Metastasis, The University of Texas Graduate School of Biomedical Sciences at Houston
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104
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Rey-Barroso J, Colo GP, Alvarez-Barrientos A, Redondo-Muñoz J, Carvajal-González JM, Mulero-Navarro S, García-Pardo A, Teixidó J, Fernandez-Salguero PM. The dioxin receptor controls β1 integrin activation in fibroblasts through a Cbp–Csk–Src pathway. Cell Signal 2013; 25:848-59. [DOI: 10.1016/j.cellsig.2013.01.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 01/07/2013] [Accepted: 01/09/2013] [Indexed: 11/30/2022]
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105
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Mukudai Y, Kondo S, Fujita A, Yoshihama Y, Shirota T, Shintani S. Tumor protein D54 is a negative regulator of extracellular matrix-dependent migration and attachment in oral squamous cell carcinoma-derived cell lines. Cell Oncol (Dordr) 2013; 36:233-45. [DOI: 10.1007/s13402-013-0131-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2013] [Indexed: 11/30/2022] Open
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106
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Goult BT, Zacharchenko T, Bate N, Tsang R, Hey F, Gingras AR, Elliott PR, Roberts GCK, Ballestrem C, Critchley DR, Barsukov IL. RIAM and vinculin binding to talin are mutually exclusive and regulate adhesion assembly and turnover. J Biol Chem 2013; 288:8238-8249. [PMID: 23389036 PMCID: PMC3605642 DOI: 10.1074/jbc.m112.438119] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 01/20/2013] [Indexed: 12/02/2022] Open
Abstract
Talin activates integrins, couples them to F-actin, and recruits vinculin to focal adhesions (FAs). Here, we report the structural characterization of the talin rod: 13 helical bundles (R1-R13) organized into a compact cluster of four-helix bundles (R2-R4) within a linear chain of five-helix bundles. Nine of the bundles contain vinculin-binding sites (VBS); R2R3 are atypical, with each containing two VBS. Talin R2R3 also binds synergistically to RIAM, a Rap1 effector involved in integrin activation. Biochemical and structural data show that vinculin and RIAM binding to R2R3 is mutually exclusive. Moreover, vinculin binding requires domain unfolding, whereas RIAM binds the folded R2R3 double domain. In cells, RIAM is enriched in nascent adhesions at the leading edge whereas vinculin is enriched in FAs. We propose a model in which RIAM binding to R2R3 initially recruits talin to membranes where it activates integrins. As talin engages F-actin, force exerted on R2R3 disrupts RIAM binding and exposes the VBS, which recruit vinculin to stabilize the complex.
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Affiliation(s)
- Benjamin T Goult
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Thomas Zacharchenko
- School of Biological Sciences, University of Liverpool, Crown Street, Liverpool L69 7ZB, United Kingdom
| | - Neil Bate
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Ricky Tsang
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Fiona Hey
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Alexandre R Gingras
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Paul R Elliott
- School of Biological Sciences, University of Liverpool, Crown Street, Liverpool L69 7ZB, United Kingdom
| | - Gordon C K Roberts
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Christoph Ballestrem
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - David R Critchley
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, United Kingdom.
| | - Igor L Barsukov
- School of Biological Sciences, University of Liverpool, Crown Street, Liverpool L69 7ZB, United Kingdom.
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107
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Ferreira JG, Diniz PMM, Andrade de Paula CA, Lobo YA, Paredes-Gamero EJ, Paschoalin T, Nogueira-Pedro A, Maza PK, Toledo MS, Suzuki E, Oliva MLV. The impaired viability of prostate cancer cell lines by the recombinant plant kallikrein inhibitor. J Biol Chem 2013; 288:13641-54. [PMID: 23511635 DOI: 10.1074/jbc.m112.404053] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Kallikreins play a pivotal role in establishing prostate cancer. RESULTS In contrast to the classical Kunitz plant inhibitor SbTI, the recombinant kallikrein inhibitor (rBbKIm) led to prostate cancer cell death, whereas fibroblast viability was not affected. CONCLUSION rBbKIm shows selective cytotoxic effect and angiogenesis inhibition against prostate cancer cells. SIGNIFICANCE New actions of rBbKIm may contribute to understanding the mechanisms of prostate cancer. Prostate cancer is the most common type of cancer, and kallikreins play an important role in the establishment of this disease. rBbKIm is the recombinant Bauhinia bauhinioides kallikreins inhibitor that was modified to include the RGD/RGE motifs of the inhibitor BrTI from Bauhinia rufa. This work reports the effects of rBbKIm on DU145 and PC3 prostate cancer cell lines. rBbKIm inhibited the cell viability of DU145 and PC3 cells but did not affect the viability of fibroblasts. rBbKIm caused an arrest of the PC3 cell cycle at the G0/G1 and G2/M phases but did not affect the DU145 cell cycle, although rBbKIm triggers apoptosis and cytochrome c release into the cytosol of both cell types. The differences in caspase activation were observed because rBbKIm treatment promoted activation of caspase-3 in DU145 cells, whereas caspase-9 but not caspase-3 was activated in PC3 cells. Because angiogenesis is important to the development of a tumor, the effect of rBbKIm in this process was also analyzed, and an inhibition of 49% was observed in in vitro endothelial cell capillary-like tube network formation. In summary, we demonstrated that different properties of the protease inhibitor rBbKIm may be explored for investigating the androgen-independent prostate cancer cell lines PC3 and DU145.
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Affiliation(s)
- Joana Gasperazzo Ferreira
- Departments of Biochemistry, Universidade Federal de São Paulo-Escola Paulista de Medicina, 04044-020, São Paulo, Brazil
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108
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Localized lipid packing of transmembrane domains impedes integrin clustering. PLoS Comput Biol 2013; 9:e1002948. [PMID: 23516344 PMCID: PMC3597534 DOI: 10.1371/journal.pcbi.1002948] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 01/11/2013] [Indexed: 12/12/2022] Open
Abstract
Integrin clustering plays a pivotal role in a host of cell functions. Hetero-dimeric integrin adhesion receptors regulate cell migration, survival, and differentiation by communicating signals bidirectionally across the plasma membrane. Thus far, crystallographic structures of integrin components are solved only separately, and for some integrin types. Also, the sequence of interactions that leads to signal transduction remains ambiguous. Particularly, it remains controversial whether the homo-dimerization of integrin transmembrane domains occurs following the integrin activation (i.e. when integrin ectodomain is stretched out) or if it regulates integrin clustering. This study employs molecular dynamics modeling approaches to address these questions in molecular details and sheds light on the crucial effect of the plasma membrane. Conducting a normal mode analysis of the intact αllbβ3 integrin, it is demonstrated that the ectodomain and transmembrane-cytoplasmic domains are connected via a membrane-proximal hinge region, thus merely transmembrane-cytoplasmic domains are modeled. By measuring the free energy change and force required to form integrin homo-oligomers, this study suggests that the β-subunit homo-oligomerization potentially regulates integrin clustering, as opposed to α-subunit, which appears to be a poor regulator for the clustering process. If α-subunits are to regulate the clustering they should overcome a high-energy barrier formed by a stable lipid pack around them. Finally, an outside-in activation-clustering scenario is speculated, explaining how further loading the already-active integrin affects its homo-oligomerization so that focal adhesions grow in size. Focal adhesions are complex, dynamic structures of multiple proteins that act as the cell's mechanical anchorage to its surrounding. Integrins are proteins linking the cell inner and outer environments, which act as a bridge that crosses the cell membrane. Integrins respond to mechanical loads exerted to them by changing their conformations. Several diseases, such as atherosclerosis and different types of cancer, are caused by altered function of integrins. Essential to the formation of focal adhesions is the process of integrin clustering. Bidirectional integrin signaling involves conformational changes in this protein, clustering, and finally the assembly of a large intracellular adhesion complex. Integrin clustering is defined as the interaction of integrins to form lateral assemblies that eventually lead to focal adhesion formation. The effect of the plasma membrane on formation of integrin clusters has been largely neglected in current literature; subsequently some apparently contradictory data has been reported by a number of researchers in the field. Using a molecular dynamics modeling approach, a computational method that simulates systems in a full-atomic scale, we probe the role of the plasma membrane in integrin clustering and hypothesize a clustering scenario that explains the relationship between integrin activation and focal adhesion growth.
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109
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Ham H, Guerrier S, Kim J, Schoon RA, Anderson EL, Hamann MJ, Lou Z, Billadeau DD. Dedicator of cytokinesis 8 interacts with talin and Wiskott-Aldrich syndrome protein to regulate NK cell cytotoxicity. THE JOURNAL OF IMMUNOLOGY 2013; 190:3661-9. [PMID: 23455509 DOI: 10.4049/jimmunol.1202792] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recently, patients with mutations in DOCK8 have been reported to have a combined immunodeficiency characterized by cutaneous viral infections and allergies. NK cells represent a first-line defense against viral infections, suggesting that DOCK8 might participate in NK cell function. In this study, we demonstrate that DOCK8-suppressed human NK cells showed defects in natural cytotoxicity as well as specific activating receptor-mediated NK cytotoxicity. Additionally, compared with control NK cells, NK cells depleted of DOCK8 showed defective conjugate formation, along with decreased polarization of LFA-1, F-actin, and cytolytic granules toward the cytotoxic synapse. Using a proteomic approach, we found that DOCK8 exists in a macromolecular complex with the Wiskott-Aldrich syndrome protein, an actin nucleation-promoting factor activated by CDC42, as well as talin, which is required for integrin-mediated adhesion. Taken together, our results demonstrate an important role for DOCK8 in NK cell effector function and provide important new mechanistic insight into how DOCK8 regulates F-actin and integrin-mediated adhesion in immune cells.
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Affiliation(s)
- Hyoungjun Ham
- Department of Immunology, College of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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110
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Discovery of platyhelminth-specific α/β-integrin families and evidence for their role in reproduction in Schistosoma mansoni. PLoS One 2012; 7:e52519. [PMID: 23300694 PMCID: PMC3531407 DOI: 10.1371/journal.pone.0052519] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 11/15/2012] [Indexed: 12/17/2022] Open
Abstract
In all metazoa, the response of cells to molecular stimuli from their environment represents a fundamental principle of regulatory processes controlling cell growth and differentiation. Among the membrane-linked receptors mediating extracellular communication processes are integrin receptors. Besides managing adhesion to the extracellular matrix or to other cells, they arrange information flow into the cells by activating intracellular signaling pathways often acting synergistically through cooperation with growth factor receptors. Although a wealth of information exists on integrins in different model organisms, there is a big gap of knowledge for platyhelminths. Here we report on the in silico detection and reconstruction of α and β integrins from free-living and parasitic platyhelminths, which according to structural and phylogenetic analyses form specific clades separate from each other and from further metazoan integrins. As representative orthologs of parasitic platyhelminths we have cloned one beta-integrin (Smβ-Int1) and four alpha-integrins (Smα-Int1 - Smα-Int4) from Schistosoma mansoni; they were characterized by molecular and biochemical analyses. Evidence is provided that Smβ-Int1 interacts and co-localizes in the reproductive organs with known schistosome cellular tyrosine kinases (CTKs), of which the Syk kinase SmTK4 appeared to be the strongest interaction partner as shown by yeast two-hybrid analyses and coimmunoprecipitation experiments. By a novel RNAi approach with adult schistosomes in vitro we demonstrate for the first time multinucleated oocytes in treated females, indicating a decisive role Smβ-Int1 during oogenesis as phenotypically analyzed by confocal laser scanning microscopy (CLSM). Our findings provide a first comprehensive overview about platyhelminth integrins, of which the parasite group exhibits unique features allowing a clear distinction from the free-living groups. Furthermore, we shed first lights on the functions of integrins in a trematode model parasite, revealing the complexity of molecular processes involved in its reproductive biology, which may be representative for other platyhelminths.
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111
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Gupton SL, Riquelme D, Hughes-Alford SK, Tadros J, Rudina SS, Hynes RO, Lauffenburger D, Gertler FB. Mena binds α5 integrin directly and modulates α5β1 function. ACTA ACUST UNITED AC 2012; 198:657-76. [PMID: 22908313 PMCID: PMC3514034 DOI: 10.1083/jcb.201202079] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Mena binds to the cytoplasmic tail of α5 integrin and modulates key
α5β1 integrin functions in adhesion, motility, and
fibrillogenesis. Mena is an Ena/VASP family actin regulator with roles in cell migration,
chemotaxis, cell–cell adhesion, tumor cell invasion, and metastasis.
Although enriched in focal adhesions, Mena has no established function within
these structures. We find that Mena forms an adhesion-regulated complex with
α5β1 integrin, a fibronectin receptor involved in cell adhesion,
motility, fibronectin fibrillogenesis, signaling, and growth factor receptor
trafficking. Mena bound directly to the carboxy-terminal portion of the
α5 cytoplasmic tail via a 91-residue region containing 13 five-residue
“LERER” repeats. In fibroblasts, the Mena–α5 complex
was required for “outside-in” α5β1 functions,
including normal phosphorylation of FAK and paxillin and formation of fibrillar
adhesions. It also supported fibrillogenesis and cell spreading and controlled
cell migration speed. Thus, fibroblasts require Mena for multiple
α5β1-dependent processes involving bidirectional interactions
between the extracellular matrix and cytoplasmic focal adhesion proteins.
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Affiliation(s)
- Stephanie L Gupton
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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112
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Yates LA, Füzéry AK, Bonet R, Campbell ID, Gilbert RJC. Biophysical analysis of Kindlin-3 reveals an elongated conformation and maps integrin binding to the membrane-distal β-subunit NPXY motif. J Biol Chem 2012; 287:37715-31. [PMID: 22989875 PMCID: PMC3488048 DOI: 10.1074/jbc.m112.415208] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 09/17/2012] [Indexed: 11/24/2022] Open
Abstract
Kindlin-3, a 75-kDa protein, has been shown to be critical for hemostasis, immunity, and bone metabolism via its role in integrin activation. The Kindlin family is hallmarked by a FERM domain comprised of F1, F2, and F3 subdomains together with an N-terminal F0 domain and a pleckstrin homology domain inserted in the F2 domain. Recombinant Kindlin-3 was cloned, expressed, and purified, and its domain organization was studied by x-ray scattering and other techniques to reveal an extended conformation. This unusual elongated structure is similar to that found in the paralogue Talin head domain. Analytical ultracentrifugation experiments indicated that Kindlin-3 forms a ternary complex with the Talin and β-integrin cytoplasmic tails. NMR showed that Kindlin-3 specifically recognizes the membrane-distal tail NPXY motif in both the β(1A) and β(1D) isoforms, although the interaction is stronger with β(1A). An upstream Ser/Thr cluster in the tails also plays a critical role. Overall these data support current biological, clinical, and mutational data on Kindlin-3/β-tail binding and provide novel insights into the overall conformation and interactions of Kindlin-3.
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Affiliation(s)
- Luke A. Yates
- From the Division of Structural Biology, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford OX3 7BN, United Kingdom and
| | - Anna K. Füzéry
- the Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Roman Bonet
- the Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Iain D. Campbell
- the Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Robert J. C. Gilbert
- From the Division of Structural Biology, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford OX3 7BN, United Kingdom and
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113
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Vial D, McKeown-Longo PJ. Epidermal growth factor (EGF) regulates α5β1 integrin activation state in human cancer cell lines through the p90RSK-dependent phosphorylation of filamin A. J Biol Chem 2012; 287:40371-80. [PMID: 23007402 DOI: 10.1074/jbc.m112.389577] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Regulation of integrin activation has important implications for tumor cell invasion and metastasis. RESULTS EGF activates ERK/p90RSK and Rho/Rho kinase signaling in A431 and DiFi colon cancer cells, leading to phosphorylation of filamin A (FLNa) and inactivation of the α5β1 integrin receptor. CONCLUSION EGF promotes α5β1 inactivation through the p90RSK-dependent phosphorylation of FLNa. SIGNIFICANCE We have identified a novel EGF-dependent mechanism controlling the α5β1 integrin activation state. Cell adhesion, motility, and invasion are regulated by the ligand-binding activity of integrin receptors, transmembrane proteins that bind to the extracellular matrix. Integrins whose conformation allows for ligand binding and appropriate functional activity are said to be in an active state. Integrin activation and subsequent ligand binding are dynamically regulated by the association of cytoplasmic proteins with integrin intracellular domains. In this study, we evaluated the role of EGF in the regulation of the activation state of the α5β1 integrin receptor for fibronectin. The addition of EGF to either A431 squamous carcinoma cells or DiFi colon cancer cells resulted in loss of α5β1-dependent adhesion to fibronectin but no loss of integrin from the cell surface. EGF activated the EGF receptor/ERK/p90RSK and Rho/Rho kinase signaling pathways. Blocking either pathway inhibited EGF-mediated loss of adhesion, suggesting that they work in parallel to regulate integrin function. EGF treatment also resulted in phosphorylation of filamin A (FLNa), which binds and inactivates β1 integrins. EGF-mediated FLNa phosphorylation was completely blocked by an inhibitor of p90RSK and partially attenuated by an inhibitor of Rho kinase, suggesting that both pathways converge on FLNa to regulate integrin function. A431 clonal cell lines expressing non-phosphorylated dominant-negative FLNa were resistant to the inhibitory effects of EGF on integrin function, whereas clonal cell lines overexpressing wild-type FLNa were more sensitive to the inhibitory effect of EGF. These data suggest that EGF-dependent inactivation of α5β1 integrin is regulated through FLNa phosphorylation and cellular contractility.
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Affiliation(s)
- Daniel Vial
- Center for Cell Biology and Cancer Research, Albany Medical College, Albany, NY 12208, USA
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Balasubramanian S, Quinones L, Kasiganesan H, Zhang Y, Pleasant DL, Sundararaj KP, Zile MR, Bradshaw AD, Kuppuswamy D. β3 integrin in cardiac fibroblast is critical for extracellular matrix accumulation during pressure overload hypertrophy in mouse. PLoS One 2012; 7:e45076. [PMID: 22984613 PMCID: PMC3440340 DOI: 10.1371/journal.pone.0045076] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 08/16/2012] [Indexed: 12/22/2022] Open
Abstract
The adhesion receptor β3 integrin regulates diverse cellular functions in various tissues. As β3 integrin has been implicated in extracellular matrix (ECM) remodeling, we sought to explore the role of β3 integrin in cardiac fibrosis by using wild type (WT) and β3 integrin null (β3-/-) mice for in vivo pressure overload (PO) and in vitro primary cardiac fibroblast phenotypic studies. Compared to WT mice, β3-/- mice upon pressure overload hypertrophy for 4 wk by transverse aortic constriction (TAC) showed a substantially reduced accumulation of interstitial fibronectin and collagen. Moreover, pressure overloaded LV from β3-/- mice exhibited reduced levels of both fibroblast proliferation and fibroblast-specific protein-1 (FSP1) expression in early time points of PO. To test if the observed impairment of ECM accumulation in β3-/- mice was due to compromised cardiac fibroblast function, we analyzed primary cardiac fibroblasts from WT and β3-/- mice for adhesion to ECM proteins, cell spreading, proliferation, and migration in response to platelet derived growth factor-BB (PDGF, a growth factor known to promote fibrosis) stimulation. Our results showed that β3-/- cardiac fibroblasts exhibited a significant reduction in cell-matrix adhesion, cell spreading, proliferation and migration. In addition, the activation of PDGF receptor associated tyrosine kinase and non-receptor tyrosine kinase Pyk2, upon PDGF stimulation were impaired in β3-/- cells. Adenoviral expression of a dominant negative form of Pyk2 (Y402F) resulted in reduced accumulation of fibronectin. These results indicate that β3 integrin-mediated Pyk2 signaling in cardiac fibroblasts plays a critical role in PO-induced cardiac fibrosis.
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Affiliation(s)
- Sundaravadivel Balasubramanian
- Cardiology Division, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Lakeya Quinones
- Cardiology Division, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Harinath Kasiganesan
- Cardiology Division, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Yuhua Zhang
- Cardiology Division, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Dorea L. Pleasant
- Cardiology Division, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Kamala P. Sundararaj
- Cardiology Division, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Michael R. Zile
- Cardiology Division, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Ralph H. Johnson Department of Veterans Affairs Medical Center, Charleston, South Carolina, United States of America
| | - Amy D. Bradshaw
- Cardiology Division, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Ralph H. Johnson Department of Veterans Affairs Medical Center, Charleston, South Carolina, United States of America
| | - Dhandapani Kuppuswamy
- Cardiology Division, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, United States of America
- * E-mail:
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β1 integrin NPXY motifs regulate kidney collecting-duct development and maintenance by induced-fit interactions with cytosolic proteins. Mol Cell Biol 2012; 32:4080-91. [PMID: 22869523 DOI: 10.1128/mcb.00568-12] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Loss of β1 integrin expression inhibits renal collecting-system development. Two highly conserved NPXY motifs in the distal β1 tail regulate integrin function by associating with phosphtyrosine binding (PTB) proteins, such as talin and kindlin. Here, we define the roles of these two tyrosines in collecting-system development and delineate the structural determinants of the distal β1 tail using nuclear magnetic resonance (NMR). Mice carrying alanine mutations have moderate renal collecting-system developmental abnormalities relative to β1-null mice. Phenylalanine mutations did not affect renal collecting-system development but increased susceptibility to renal injury. NMR spectra in bicelles showed the distal β1 tail is disordered and does not interact with the model membrane surface. Alanine or phenylalanine mutations did not alter β1 structure or interactions between α and β1 subunit transmembrane/cytoplasmic domains; however, they did decrease talin and kindlin binding. Thus, these studies highlight the fact that the functional roles of the NPXY motifs are organ dependent. Moreover, the β1 cytoplasmic tail, in the context of the adjacent transmembrane domain in bicelles, is significantly different from the more ordered, membrane-associated β3 integrin tail. Finally, tyrosine mutations of β1 NPXY motifs induce phenotypes by disrupting their interactions with critical integrin binding proteins like talins and kindlins.
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Abstract
The inside-out signaling of integrins regulates the ligand-binding affinity of the cell surface receptors in response to changes in the environment for cell survival. The specific binding to the cytoplasmic tail of integrin's β subunit by the intracellular protein talin is the key step of inside-out signaling. A "pull-push" mechanism has been proposed to explain how the PIP2-enriched membrane disrupts the dual auto-inhibition of the N-terminal talin-FERM domain by the C-terminal talin-rod domain such that activated talin-FERM can reach the β-tail for integrin activation.
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Wong MC, Schwarzbauer JE. Gonad morphogenesis and distal tip cell migration in the Caenorhabditis elegans hermaphrodite. WILEY INTERDISCIPLINARY REVIEWS. DEVELOPMENTAL BIOLOGY 2012; 1:519-31. [PMID: 23559979 PMCID: PMC3614366 DOI: 10.1002/wdev.45] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cell migration and morphogenesis are key events in tissue development and organogenesis. In Caenorhabditis elegans, the migratory path of the distal tip cells determines the morphology of the hermaphroditic gonad. The distal tip cells undergo a series of migratory phases interspersed with turns to form the gonad. A wide variety of genes have been identified as crucial to this process, from genes that encode components and modifiers of the extracellular matrix to signaling proteins and transcriptional regulators. The connections between extracellular and transmembrane protein functions and intracellular pathways are essential for distal tip cell migration, and the integration of this information governs gonad morphogenesis and determines gonad size and shape.
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Affiliation(s)
- Ming-Ching Wong
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
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Abstract
Transforming growth factor-β (TGF-β) has roles in embryonic development, the prevention of inappropriate inflammation and tumour suppression. However, TGF-β signalling also regulates pathological epithelial-to-mesenchymal transition (EMT), inducing or progressing a number of diseases ranging from inflammatory disorders, to fibrosis and cancer. However, TGF-β signalling does not proceed linearly but rather induces a complex network of cascades that mutually influence each other and cross-talk with other pathways to successfully induce EMT. Particularly, there is substantial evidence for cross-talk between αV integrins and TGF-β during EMT, and anti-integrin therapeutics are under development as treatments for TGF-β-related disorders. However, TGF-β's complex signalling network makes the development of therapeutics to block TGF-β-mediated pathology challenging. Moreover, despite our current understanding of integrins and TGF-β function during EMT, the precise mechanism of their role during physiological versus pathological EMT is not fully understood. This review focuses on the circle of regulation between αV integrin and TGF-β signalling during TGF-β induced EMT, which pose as a significant driver to many known TGF-β-mediated disorders.
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Affiliation(s)
- Fahmy A Mamuya
- Department of Biological Sciences, University of Delaware, Newark, DE, USA
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Kurtz L, Kao L, Newman D, Kurtz I, Zhu Q. Integrin αIIbβ3 inside-out activation: an in situ conformational analysis reveals a new mechanism. J Biol Chem 2012; 287:23255-65. [PMID: 22613710 DOI: 10.1074/jbc.m112.360966] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Integrins are a family of heterodimeric adhesion receptors that transmit signals bi-directionally across the plasma membranes. The transmembrane domain (TM) of integrin plays a critical role in mediating transition of the receptor from the default inactive to the active state on the cell surfaces. In this study, we successfully applied the substituted cysteine scanning accessibility method to determine the intracellular border of the integrin α(IIb)β(3) TM in the inactive and active states in living cells. We examined the aqueous accessibility of 75 substituted cysteines comprising the C terminus of both α(IIb) and β(3) TMs, the intracellular membrane-proximal regions, and the whole cytoplasmic tails, to the labeling of a membrane-permeable, cysteine-specific chemical biotin maleimide (BM). The active state of integrin α(IIb)β(3) heterodimer was generated by co-expression of activating partners with the cysteine-substituted constructs. Our data revealed that, in the inactive state, the intracellular lipid/aqueous border of α(IIb) TM was at Lys(994) and β(3) TM was at Phe(727) respectively; in the active state, the border of α(IIb) TM shifted to Pro(998), whereas the border of β(3) TM remained unchanged, suggesting that complex conformational changes occurred in the TMs upon α(IIb)β(3) inside-out activation. On the basis of the results, we propose a new inside-out activation mechanism for integrin α(IIb)β(3) and by inference, all of the integrins in their native cellular environment.
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Affiliation(s)
- Lisa Kurtz
- Department of Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California 90095-1689, USA
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Bate N, Gingras AR, Bachir A, Horwitz R, Ye F, Patel B, Goult BT, Critchley DR. Talin contains a C-terminal calpain2 cleavage site important in focal adhesion dynamics. PLoS One 2012; 7:e34461. [PMID: 22496808 PMCID: PMC3319578 DOI: 10.1371/journal.pone.0034461] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 02/15/2012] [Indexed: 12/31/2022] Open
Abstract
Talin is a large (∼2540 residues) dimeric adaptor protein that associates with the integrin family of cell adhesion molecules in cell-extracellular matrix junctions (focal adhesions; FAs), where it both activates integrins and couples them to the actin cytoskeleton. Calpain2-mediated cleavage of talin between the head and rod domains has previously been shown to be important in FA turnover. Here we identify an additional calpain2-cleavage site that removes the dimerisation domain from the C-terminus of the talin rod, and show that an E2492G mutation inhibits calpain cleavage at this site in vitro, and increases the steady state levels of talin1 in vivo. Expression of a GFP-tagged talin1 E2492G mutant in CHO.K1 cells inhibited FA turnover and the persistence of cell protrusion just as effectively as a L432G mutation that inhibits calpain cleavage between the talin head and rod domains. Moreover, incorporation of both mutations into a single talin molecule had an additive effect clearly demonstrating that calpain cleavage at both the N- and C-terminal regions of talin contribute to the regulation of FA dynamics. However, the N-terminal site was more sensitive to calpain cleavage suggesting that lower levels of calpain are required to liberate the talin head and rod fragments than are needed to clip off the C-terminal dimerisation domain. The talin head and rod liberated by calpain2 cleavage have recently been shown to play roles in an integrin activation cycle important in FA turnover and in FAK-dependent cell cycle progression respectively. The half-life of the talin head is tightly regulated by ubiquitination and we suggest that removal of the C-terminal dimerisation domain from the talin rod may provide a mechanism both for terminating the signalling function of the talin rod and indeed for inactivating full-length talin thereby promoting FA turnover at the rear of the cell.
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Affiliation(s)
- Neil Bate
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
| | | | - Alexia Bachir
- Department of Cell Biology, Univeristy of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Rick Horwitz
- Department of Cell Biology, Univeristy of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Feng Ye
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Bipin Patel
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
| | - Benjamin T. Goult
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
| | - David R. Critchley
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
- * E-mail:
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122
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Yue J, Zhang K, Chen J. Role of integrins in regulating proteases to mediate extracellular matrix remodeling. CANCER MICROENVIRONMENT 2012; 5:275-83. [PMID: 22437309 DOI: 10.1007/s12307-012-0101-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 03/01/2012] [Indexed: 01/09/2023]
Abstract
The extracellular matrix (ECM) is an extracellular scaffold composed of complex mixtures of proteins that plays a pivotal role in tumor progression. ECM remodeling is crucial for tumor migration and invasion during the process of metastasis. ECM can be remodeled by several processes including synthesis, contraction and proteolytic degradation. In order to cross through the ECM barriers, malignant cells produce a spectrum of extracellular proteinases including matrix metalloproteinases (MMPs), serine proteases (mainly the urokinase plasminogen activator (uPA) system) and cysteine proteases to degrade ECM components. As major adhesion molecules to support cell attachment to ECM, integrins play critical roles in tumor progression by enhancing tumor cell survival, migration and invasion. Previous studies have shown that integrins can regulate the expression and activity of these proteases through different pathways. This review summarizes the roles of MMPs and uPA system in ECM remodeling and discusses the regulatory functions of integrins on these proteases in invasive tumors.
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Affiliation(s)
- Jiao Yue
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 YueYang Road, Shanghai, 200031, China
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Praekelt U, Kopp PM, Rehm K, Linder S, Bate N, Patel B, Debrand E, Manso AM, Ross RS, Conti F, Zhang MZ, Harris RC, Zent R, Critchley DR, Monkley SJ. New isoform-specific monoclonal antibodies reveal different sub-cellular localisations for talin1 and talin2. Eur J Cell Biol 2012; 91:180-91. [PMID: 22306379 PMCID: PMC3629562 DOI: 10.1016/j.ejcb.2011.12.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 12/13/2011] [Accepted: 12/19/2011] [Indexed: 11/24/2022] Open
Abstract
Talins are adaptor proteins that connect the integrin family of cell adhesion receptors to cytoskeletal actin. Vertebrates express two closely related talins encoded by separate genes, and while it is well established that talin1 plays a key role in cell adhesion and spreading, little is known about the role of talin2. To facilitate such studies, we report the characterisation of 4 new isoform-specific talin mouse monoclonal antibodies that work in Western blotting, immuno-precipitation, immuno-fluorescence and immuno-histochemistry. Using these antibodies, we show that talin1 and talin2 do not form heterodimers, and that they are differentially localised within the cell. Talin1 was concentrated in peripheral focal adhesions while talin2 was observed in both focal and fibrillar adhesions, and knock-down of talin2 compromised fibronectin fibrillogenesis. Although differentiated human macrophages express both isoforms, only talin1 showed discrete staining and was localised to the ring structure of podosomes. However, siRNA-mediated knock-down of macrophage talin2 led to a significant reduction in podosomal matrix degradation. We have also used the antibodies to localise each isoform in tissue sections using both cryostat and paraffin-embedded material. In skeletal muscle talin2 was localised to both myotendinous junctions and costameres while talin1 was restricted to the former structure. In contrast, both isoforms co-localised in kidney with staining of the glomerulus, and the tubular epithelial and interstitial cells of the cortex and medulla. We anticipate that these antibodies will form a valuable resource for future studies on the function of the two major talin isoforms.
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Affiliation(s)
- Uta Praekelt
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Petra M. Kopp
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Kerstin Rehm
- University Medical Center Eppendorf, 20246 Hamburg, Germany
| | - Stefan Linder
- University Medical Center Eppendorf, 20246 Hamburg, Germany
| | - Neil Bate
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Bipin Patel
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Emmanuel Debrand
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Ana Maria Manso
- Department of Medicine, University of California at San Diego, School of Medicine, La Jolla, CA, USA
- VA Healthcare San Diego, CA 92161, USA
| | - Robert S. Ross
- Department of Medicine, University of California at San Diego, School of Medicine, La Jolla, CA, USA
- VA Healthcare San Diego, CA 92161, USA
| | - Franceso Conti
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Ming-Zhi Zhang
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, North Nashville, TN 37232, USA
| | - Raymond C. Harris
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, North Nashville, TN 37232, USA
- Department of Medicine, Veterans Affairs Hospital, Nashville, TN 37212, USA
| | - Roy Zent
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, North Nashville, TN 37232, USA
- Department of Medicine, Veterans Affairs Hospital, Nashville, TN 37212, USA
| | - David R. Critchley
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Susan J. Monkley
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
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Prostaglandins in cancer cell adhesion, migration, and invasion. Int J Cell Biol 2012; 2012:723419. [PMID: 22505934 PMCID: PMC3299390 DOI: 10.1155/2012/723419] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 10/08/2011] [Indexed: 12/21/2022] Open
Abstract
Prostaglandins exert a profound influence over the adhesive, migratory, and invasive behavior of cells during the development and progression of cancer. Cyclooxygenase-2 (COX-2) and microsomal prostaglandin E2 synthase-1 (mPGES-1) are upregulated in inflammation and cancer. This results in the production of prostaglandin E2 (PGE2), which binds to and activates G-protein-coupled prostaglandin E1–4 receptors (EP1–4). Selectively targeting the COX-2/mPGES-1/PGE2/EP1–4 axis of the prostaglandin pathway can reduce the adhesion, migration, invasion, and angiogenesis. Once stimulated by prostaglandins, cadherin adhesive connections between epithelial or endothelial cells are lost. This enables cells to invade through the underlying basement membrane and extracellular matrix (ECM). Interactions with the ECM are mediated by cell surface integrins by “outside-in signaling” through Src and focal adhesion kinase (FAK) and/or “inside-out signaling” through talins and kindlins. Combining the use of COX-2/mPGES-1/PGE2/EP1–4 axis-targeted molecules with those targeting cell surface adhesion receptors or their downstream signaling molecules may enhance cancer therapy.
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Chang IA, Oh MJ, Kim MH, Park SK, Kim BG, Namgung U. Vimentin phosphorylation by Cdc2 in Schwann cell controls axon growth via β1-integrin activation. FASEB J 2012; 26:2401-13. [PMID: 22371530 DOI: 10.1096/fj.11-199018] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Although preconditioning injury on the peripheral nerve induces axonal regenerative capacity in neurons, it is not known whether similar lesion effects occur in glial cells. Here we demonstrate that Schwann cells are activated by peripheral nerve preinjury and primed to mediate axon regeneration. Cdc2, which was induced from Schwann cells after sciatic nerve injury, phosphorylated vimentin almost exclusively in the distal nerve area. Phospho-vimentin-positive Schwann cells showed increased migration activity and were in close contact with process outgrowth of co-cultured neurons. Vimentin phosphorylation by Cdc2 was involved in β1-integrin activation leading to FAK phoshorylation and associated with Erk1/2 activation in Schwann cells. Neurite outgrowth of dorsal root ganglion neurons was increased by co-culture with activated Schwann cells, in which phospho-vimentin signaling was transmitted into β1-integrin activation. Then neurite outgrowth was suppressed by genetic depletion of phospho-vimentin and β1 integrin as well as inhibition of vimentin phosphorylation by Cdc2 inhibitor purvalanol A. The sciatic nerve graft harboring activated Schwann cells into the spinal cord induced Schwann cell migration beyond the graft-host barrier and facilitated regeneration of spinal axons, which was inhibited by purvalanol A pretreatment of the graft. This is the first report to our knowledge demonstrating that activation of phospho-vimentin linked to β1-integrin pathway may mediate transcellular signaling to promote axon growth.
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Affiliation(s)
- In Ae Chang
- Department of Oriental Medicine, Daejeon University, Daejeon 300-716, Republic of Korea
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126
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Hauschner H, Mor-Cohen R, Seligsohn U, Rosenberg N. A mutation in the β3 cytoplasmic tail causes variant Glanzmann thrombasthenia by abrogating transition of αIIb β3 to an active state. J Thromb Haemost 2012; 10:289-97. [PMID: 22136613 DOI: 10.1111/j.1538-7836.2011.04577.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND The cytoplasmic tails of α(IIb) and β(3) regulate essential α(IIb) β(3) functions. We previously described a variant Glanzmann thrombasthenia mutation in the β(3) cytoplasmic tail, IVS14: -3C>G, which causes a frameshift with an extension of β(3) by 40 residues. OBJECTIVES The aim of this study was to characterize the mechanism by which the mutation abrogates transition of α(IIb) β(3) from a resting state to an active state. METHODS We expressed the natural mutation, termed 742ins, and three artificial mutations in baby hamster kidney (BHK) cells along with wild-type (WT) α(IIb) as follows: β(3) -742stop, a truncated mutant to evaluate the effect of deleted residues; β(3) -749stop, a truncated mutant that preserves the NPLY conserved sequence; and β(3) -749ins, in which the aberrant tail begins after the conserved sequence. Flow cytometry was used to determine ligand binding to BHK cells. RESULTS AND CONCLUSIONS Surface expression of α(IIb) β(3) of all four mutants was at least 60% of WT expression, but there was almost no binding of soluble fibrinogen following activation with activating antibodies (anti-ligand-induced-binding-site 6 [antiLIBS6] or PT25-2). Activation of the α(IIb) β(3) mutants was only achieved when both PT25-2 and antiLIBS6 were used together or following treatment with dithiothreitol. These data suggest that the ectodomain of the four mutants is tightly locked in a resting conformation but can be forced to become active by strong stimuli. These data and those of others indicate that the middle part of the β(3) tail is important for maintaining α(IIb) β(3) in a resting conformation.
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Affiliation(s)
- H Hauschner
- Amalia Biron Research Institute of Thrombosis and Hemostasis, Chaim Sheba Medical Center, Tel Hashomer and Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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Eva R, Andrews MR, Franssen EHP, Fawcett JW. Intrinsic mechanisms regulating axon regeneration: an integrin perspective. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2012; 106:75-104. [PMID: 23211460 DOI: 10.1016/b978-0-12-407178-0.00004-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Adult central nervous system (CNS) axons fail to regenerate after injury because of inhibitory factors in the surrounding environment and a low intrinsic regenerative capacity. Axons in the adult peripheral nervous system have a higher regenerative capacity, due in part to the presence of certain integrins-receptors for the extracellular matrix. Integrins are critical for axon growth during the development of the nervous system but are absent from some adult CNS axons. Here, we discuss the intrinsic mechanisms that regulate axon regeneration and examine the role of integrins. As correct localization is paramount to integrin function, we further discuss the mechanisms that regulate integrin traffic toward the axonal growth cone.
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Affiliation(s)
- Richard Eva
- Cambridge Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
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Hanein D, Horwitz AR. The structure of cell-matrix adhesions: the new frontier. Curr Opin Cell Biol 2011; 24:134-40. [PMID: 22196929 DOI: 10.1016/j.ceb.2011.12.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 11/30/2011] [Accepted: 12/01/2011] [Indexed: 12/18/2022]
Abstract
Adhesions between the cell and the extracellular matrix (ECM) are mechanosensitive multi-protein assemblies that transmit force across the cell membrane and regulate biochemical signals in response to the chemical and mechanical environment. These combined functions in force transduction, signaling and mechanosensing contribute to cellular phenotypes that span development, homeostasis and disease. These adhesions form, mature and disassemble in response to actin organization and physical forces that originate from endogenous myosin activity or external forces by the extracellular matrix. Despite advances in our understanding of the protein composition, interactions and regulation, our understanding of matrix adhesion structure and organization, how forces affect this organization, and how these changes dictate specific signaling events is limited. Insights across multiple structural levels are acutely needed to elucidate adhesion structure and ultimately the molecular basis of signaling and mechanotransduction. Here we describe the challenges and recent advances and prospects for unraveling the structure of cell-matrix adhesions and their response to force.
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Affiliation(s)
- Dorit Hanein
- Bioinformatics and Systems Biology Program, Sanford Burnham Medical Research Institute, La Jolla, CA, United States.
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Li Q, Ding X, Thomas JJ, Harding CV, Pecora ND, Ziady AG, Shank S, Boom WH, Lancioni CL, Rojas RE. Rv2468c, a novel Mycobacterium tuberculosis protein that costimulates human CD4+ T cells through VLA-5. J Leukoc Biol 2011; 91:311-20. [PMID: 22158781 DOI: 10.1189/jlb.0711364] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Mtb regulates many aspects of the host immune response, including CD4+ T lymphocyte responses that are essential for protective immunity to Mtb, and Mtb effects on the immune system are paradoxical, having the capacity to inhibit (immune evasion) and to activate (adjuvant effect) immune cells. Mtb regulates CD4+ T cells indirectly (e.g., by manipulation of APC function) and directly, via integrins and TLRs expressed on T cells. We now report that previously uncharacterized Mtb protein Rv2468c/MT2543 can directly regulate human CD4+ T cell activation by delivering costimulatory signals. When combined with TCR stimulation (e.g., anti-CD3), Rv2468c functioned as a direct costimulator for CD4+ T cells, inducing IFN-γ secretion and T cell proliferation. Studies with blocking antibodies and soluble RGD motifs demonstrated that Rv2468c engaged integrin VLA-5 (α5β1) on CD4+ T cells through its FN-like RGD motif. Costimulation by Rv2468c induced phosphorylation of FAKs and Pyk2. These results reveal that by expressing molecules that mimic host protein motifs, Mtb can directly engage receptors on CD4+ T cells and regulate their function. Rv2468c-induced costimulation of CD4+ T cells could have implications for TB immune pathogenesis and Mtb adjuvant effect.
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Affiliation(s)
- Qing Li
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
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Lahlou H, Muller WJ. β1-integrins signaling and mammary tumor progression in transgenic mouse models: implications for human breast cancer. Breast Cancer Res 2011; 13:229. [PMID: 22264244 PMCID: PMC3326542 DOI: 10.1186/bcr2905] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Consistent with their essential role in cell adhesion to the extracellular matrix, integrins and their associated signaling pathways have been shown to be involved in cell proliferation, migration, invasion and survival, processes required in both tumorigenesis and metastasis. β1-integrins represent the predominantly expressed integrins in mammary epithelial cells and have been proven crucial for mammary gland development and differentiation. Here we provide an overview of the studies that have used transgenic mouse models of mammary tumorigenesis to establish β1-integrin as a critical mediator of breast cancer progression and thereby as a potential therapeutic target for the development of new anticancer strategies.
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Affiliation(s)
- Hicham Lahlou
- Goodman Cancer Centre, McGill University, 1160 Pine Avenue West, Montreal, Québec, Canada
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132
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de Paula CAA, Coulson-Thomas VJ, Ferreira JG, Maza PK, Suzuki E, Nakahata AM, Nader HB, Sampaio MU, Oliva MLV. Enterolobium contortisiliquum trypsin inhibitor (EcTI), a plant proteinase inhibitor, decreases in vitro cell adhesion and invasion by inhibition of Src protein-focal adhesion kinase (FAK) signaling pathways. J Biol Chem 2011; 287:170-182. [PMID: 22039045 DOI: 10.1074/jbc.m111.263996] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Tumor cell invasion is vital for cancer progression and metastasis. Adhesion, migration, and degradation of the extracellular matrix are important events involved in the establishment of cancer cells at a new site, and therefore molecular targets are sought to inhibit such processes. The effect of a plant proteinase inhibitor, Enterolobium contortisiliquum trypsin inhibitor (EcTI), on the adhesion, migration, and invasion of gastric cancer cells was the focus of this study. EcTI showed no effect on the proliferation of gastric cancer cells or fibroblasts but inhibited the adhesion, migration, and cell invasion of gastric cancer cells; however, EcTI had no effect upon the adhesion of fibroblasts. EcTI was shown to decrease the expression and disrupt the cellular organization of molecules involved in the formation and maturation of invadopodia, such as integrin β1, cortactin, neuronal Wiskott-Aldrich syndrome protein, membrane type 1 metalloprotease, and metalloproteinase-2. Moreover, gastric cancer cells treated with EcTI presented a significant decrease in intracellular phosphorylated Src and focal adhesion kinase, integrin-dependent cell signaling components. Together, these results indicate that EcTI inhibits the invasion of gastric cancer cells through alterations in integrin-dependent cell signaling pathways.
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Affiliation(s)
- Cláudia Alessandra Andrade de Paula
- Department of Biochemistry and Molecular Biology, Universidade Federal de São Paulo-Escola Paulista de Medicina, São Paulo, 04044-020, Brazil
| | - Vivien Jane Coulson-Thomas
- Department of Biochemistry and Molecular Biology, Universidade Federal de São Paulo-Escola Paulista de Medicina, São Paulo, 04044-020, Brazil
| | - Joana Gasperazzo Ferreira
- Department of Biochemistry and Molecular Biology, Universidade Federal de São Paulo-Escola Paulista de Medicina, São Paulo, 04044-020, Brazil
| | - Paloma Korehisa Maza
- Department of Microbiology, Immunology, and Parasitology, Universidade Federal de São Paulo-Escola Paulista de Medicina, 04044-020 São Paulo, Brazil
| | - Erika Suzuki
- Department of Microbiology, Immunology, and Parasitology, Universidade Federal de São Paulo-Escola Paulista de Medicina, 04044-020 São Paulo, Brazil
| | - Adriana Miti Nakahata
- Department of Biochemistry and Molecular Biology, Universidade Federal de São Paulo-Escola Paulista de Medicina, São Paulo, 04044-020, Brazil
| | - Helena Bonciani Nader
- Department of Biochemistry and Molecular Biology, Universidade Federal de São Paulo-Escola Paulista de Medicina, São Paulo, 04044-020, Brazil
| | - Misako Uemura Sampaio
- Department of Biochemistry and Molecular Biology, Universidade Federal de São Paulo-Escola Paulista de Medicina, São Paulo, 04044-020, Brazil
| | - Maria Luiza V Oliva
- Department of Biochemistry and Molecular Biology, Universidade Federal de São Paulo-Escola Paulista de Medicina, São Paulo, 04044-020, Brazil.
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133
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Tolomelli A, Gentilucci L, Mosconi E, Viola A, Dattoli SD, Baiula M, Spampinato S, Belvisi L, Civera M. Development of Isoxazoline-Containing Peptidomimetics as Dual αvβ3 and α5β1 Integrin Ligands. ChemMedChem 2011; 6:2264-72. [DOI: 10.1002/cmdc.201100372] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2011] [Revised: 08/30/2011] [Indexed: 02/02/2023]
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134
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Ali O, Guillou H, Destaing O, Albigès-Rizo C, Block MR, Fourcade B. Cooperativity between integrin activation and mechanical stress leads to integrin clustering. Biophys J 2011; 100:2595-604. [PMID: 21641304 DOI: 10.1016/j.bpj.2011.03.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 03/01/2011] [Accepted: 03/17/2011] [Indexed: 12/31/2022] Open
Abstract
Integrins are transmembrane receptors involved in crucial cellular biological functions such as migration, adhesion, and spreading. Upon the modulation of integrin affinity toward their extracellular ligands by cytoplasmic proteins (inside-out signaling) these receptors bind to their ligands and cluster into nascent adhesions. This clustering results in the increase in the mechanical linkage among the cell and substratum, cytoskeleton rearrangements, and further outside-in signaling. Based on experimental observations of the distribution of focal adhesions in cells attached to micropatterned surfaces, we introduce a physical model relying on experimental numerical constants determined in the literature. In this model, allosteric integrin activation works in synergy with the stress build by adhesion and the membrane rigidity to allow the clustering to nascent adhesions independently of actin but dependent on the integrin diffusion onto adhesive surfaces. The initial clustering could provide a template to the mature adhesive structures. Predictions of our model for the organization of focal adhesions are discussed in comparison with experiments using adhesive protein microarrays.
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Affiliation(s)
- O Ali
- INSERM U823-CNRS ERL 5284, Institut Albert Bonniot, Equipe Dysad, Site Santé, La Tronche, Grenoble cedex 9, France
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135
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Mu Y, Sundar R, Thakur N, Ekman M, Gudey SK, Yakymovych M, Hermansson A, Dimitriou H, Bengoechea-Alonso MT, Ericsson J, Heldin CH, Landström M. TRAF6 ubiquitinates TGFβ type I receptor to promote its cleavage and nuclear translocation in cancer. Nat Commun 2011; 2:330. [PMID: 21629263 PMCID: PMC3113296 DOI: 10.1038/ncomms1332] [Citation(s) in RCA: 146] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 05/04/2011] [Indexed: 01/08/2023] Open
Abstract
Transforming growth factor β (TGFβ) is a pluripotent cytokine promoting epithelial cell plasticity during morphogenesis and tumour progression. TGFβ binding to type II and type I serine/threonine kinase receptors (TβRII and TβRI) causes activation of different intracellular signaling pathways. TβRI is associated with the ubiquitin ligase tumor necrosis factor receptor (TNFR)-associated factor 6 (TRAF6). Here we show that TGFβ, via TRAF6, causes Lys63-linked polyubiquitination of TβRI, promoting cleavage of TβRI by TNF-alpha converting enzyme (TACE), in a PKCζ-dependent manner. The liberated intracellular domain (ICD) of TβRI associates with the transcriptional regulator p300 to activate genes involved in tumour cell invasiveness, such as Snail and MMP2. Moreover, TGFβ-induced invasion of cancer cells is TACE- and PKCζ- dependent and the TβRI ICD is localized in the nuclei of different kinds of tumour cells in tissue sections. Thus, our data reveal a specific role for TβRI in TGFβ mediated tumour invasion. TGFβ can function as both a tumour suppressor and tumour promoter under different cellular contexts. Here, the cleavage product of the TGFβ type I receptor is shown to be generated in a TGFβ-dependent manner, and can induce the expression of genes involved in tumour cell invasion.
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Affiliation(s)
- Yabing Mu
- Rudbeck Laboratory, Department of Immunology, Genetics and Pathology, SE-751 85 Uppsala, Sweden
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136
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Holmes RS, Rout UK. Comparative studies of vertebrate Beta integrin genes and proteins: ancient genes in vertebrate evolution. Biomolecules 2011; 1:3-31. [PMID: 24970121 PMCID: PMC4030831 DOI: 10.3390/biom1010003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 08/14/2011] [Accepted: 08/15/2011] [Indexed: 12/31/2022] Open
Abstract
Intregins are heterodimeric α- and β-subunit containing membrane receptor proteins which serve various cell adhesion roles in tissue repair, hemostasis, immune response, embryogenesis and metastasis. At least 18 α- (ITA or ITGA) and 8 β-integrin subunits (ITB or ITGB) are encoded on mammalian genomes. Comparative ITB amino acid sequences and protein structures and ITB gene locations were examined using data from several vertebrate genome projects. Vertebrate ITB genes usually contained 13-16 coding exons and encoded protein subunits with ~800 amino acids, whereas vertebrate ITB4 genes contained 36-39 coding exons and encoded larger proteins with ~1800 amino acids. The ITB sequences exhibited several conserved domains including signal peptide, extracellular β-integrin, β-tail domain and integrin β-cytoplasmic domains. Sequence alignments of the integrin β-cytoplasmic domains revealed highly conserved regions possibly for performing essential functions and its maintenance during vertebrate evolution. With the exception of the human ITB8 sequence, the other ITB sequences shared a predicted 19 residue α-helix for this region. Potential sites for regulating human ITB gene expression were identified which included CpG islands, transcription factor binding sites and microRNA binding sites within the 3'-UTR of human ITB genes. Phylogenetic analyses examined the relationships of vertebrate beta-integrin genes which were consistent with four major groups: 1: ITB1, ITB2, ITB7; 2: ITB3, ITB5, ITB6; 3: ITB4; and 4: ITB8 and a common evolutionary origin from an ancestral gene, prior to the appearance of fish during vertebrate evolution. The phylogenetic analyses revealed that ITB4 is the most likely primordial form of the vertebrate β integrin subunit encoding genes, that is the only β subunit expressed as a constituent of the sole integrin receptor 'α6β4' in the hemidesmosomes of unicellular organisms.
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Affiliation(s)
- Roger S Holmes
- School of Biomolecular and Physical Sciences, Griffith University, Nathan, 4111QLD, Australia.
| | - Ujjwal K Rout
- Department of Surgery, University of Mississippi Medical Center, Jackson, MS 38677, USA.
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137
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Liu J, He X, Qi Y, Tian X, Monkley SJ, Critchley DR, Corbett SA, Lowry SF, Graham AM, Li S. Talin1 regulates integrin turnover to promote embryonic epithelial morphogenesis. Mol Cell Biol 2011; 31:3366-77. [PMID: 21670148 PMCID: PMC3147785 DOI: 10.1128/mcb.01403-10] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 05/21/2011] [Indexed: 12/17/2022] Open
Abstract
Talin is a cytoskeletal protein that binds to integrin β cytoplasmic tails and regulates integrin activation. Talin1 ablation in mice disrupts gastrulation and causes embryonic lethality. However, the role of talin in mammalian epithelial morphogenesis is poorly understood. Here we demonstrate that embryoid bodies (EBs) differentiated from talin1-null embryonic stem cells are defective in integrin adhesion complex assembly, epiblast elongation, and lineage differentiation. These defects are accompanied by a significant reduction in integrin β1 protein levels due to accelerated degradation through an MG-132-sensitive proteasomal pathway. Overexpression of integrin β1 or MG-132 treatment in mutant EBs largely rescues the phenotype. In addition, epiblast cells isolated from talin1-null EBs exhibit impaired cell spreading and focal adhesion formation. Transfection of the mutant cells with green fluorescent protein (GFP)-tagged wild-type but not mutant talin1 that is defective in integrin binding normalizes integrin β1 protein levels and restores focal adhesion formation. Significantly, cell adhesion and spreading are also improved by overexpression of integrin β1. All together, these results suggest that talin1 binding to integrin promotes epiblast adhesion and morphogenesis in part by preventing integrin β1 degradation.
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Affiliation(s)
- Jie Liu
- Department of Surgery, Robert Wood Johnson Medical School-UMDNJ, New Brunswick, New Jersey 08903
| | - Xiaowen He
- Department of Surgery, Robert Wood Johnson Medical School-UMDNJ, New Brunswick, New Jersey 08903
| | - Yanmei Qi
- Department of Surgery, Robert Wood Johnson Medical School-UMDNJ, New Brunswick, New Jersey 08903
| | - Xiaoxiang Tian
- Department of Surgery, Robert Wood Johnson Medical School-UMDNJ, New Brunswick, New Jersey 08903
| | - Susan J. Monkley
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
| | - David R. Critchley
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
| | - Siobhan A. Corbett
- Department of Surgery, Robert Wood Johnson Medical School-UMDNJ, New Brunswick, New Jersey 08903
| | - Stephen F. Lowry
- Department of Surgery, Robert Wood Johnson Medical School-UMDNJ, New Brunswick, New Jersey 08903
| | - Alan M. Graham
- Department of Surgery, Robert Wood Johnson Medical School-UMDNJ, New Brunswick, New Jersey 08903
| | - Shaohua Li
- Department of Surgery, Robert Wood Johnson Medical School-UMDNJ, New Brunswick, New Jersey 08903
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