101
|
Høyer-Hansen G, Pessara U, Holm A, Pass J, Weidle U, Danø K, Behrendt N. Urokinase-catalysed cleavage of the urokinase receptor requires an intact glycolipid anchor. Biochem J 2001; 358:673-9. [PMID: 11535128 PMCID: PMC1222101 DOI: 10.1042/0264-6021:3580673] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Urokinase (uPA) has the striking ability to cleave its receptor, uPAR, thereby inactivating the binding potential of this molecule. Here we demonstrate that the glycosylphosphatidylinositol (GPI) anchor of uPAR, which is attached to the third domain, is an important determinant in governing this reaction, even though the actual cleavage occurs between the first and second domains. Purified full-length GPI-anchored uPAR (GPI-uPAR) proved much more susceptible to uPA-mediated cleavage than recombinant truncated soluble uPAR (suPAR), which lacks the glycolipid anchor. This was not a general difference in proteolytic susceptibility since GPI-uPAR and suPAR were cleaved with equal efficiency by plasmin. Since the amino acid sequences of GPI-uPAR and suPAR are identical except for the C-terminal truncation, the different cleavage patterns suggest that the two uPAR variants differ in the conformation or the flexibility of the linker region between domains 1 and 2. This was supported by the fact that an antibody to the peptide AVTYSRSRYLE, amino acids 84-94 in the linker region, recognizes GPI-uPAR but not suPAR. This difference in the linker region is thus caused by a difference in a remote hydrophobic region. In accordance with this model, when the hydrophobic lipid moiety was removed from the glycolipid anchor by phospholipase C, low concentrations of uPA could no longer cleave the modified GPI-uPAR and the reactivity to the peptide antibody was greatly decreased. Naturally occurring suPAR, purified from plasma, was found to have a similar resistance to uPA cleavage as phospholipase C-treated GPI-uPAR and recombinant suPAR.
Collapse
Affiliation(s)
- G Høyer-Hansen
- Finsen Laboratory, Rigshospitalet, Strandboulevarden 49, DK-2100 Copenhagen Ø, Denmark.
| | | | | | | | | | | | | |
Collapse
|
102
|
|
103
|
Herz J, Strickland DK. LRP: a multifunctional scavenger and signaling receptor. J Clin Invest 2001; 108:779-84. [PMID: 11560943 PMCID: PMC200939 DOI: 10.1172/jci13992] [Citation(s) in RCA: 375] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- J Herz
- Department of Molecular Genetics, Dallas, Texas, USA.
| | | |
Collapse
|
104
|
Maru Y, Hanks SK, Shibuya M. The tubulogenic activity associated with an activated form of Flt-1 kinase is dependent on focal adhesion kinase. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1540:147-53. [PMID: 11513976 DOI: 10.1016/s0167-4889(01)00127-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Focal adhesion kinase (FAK) is known to be located at the intersection between extracellular matrix and growth factor signaling pathways to regulate cell motility. We have shown previously that an activated form (BCR-FLTm1) of Flt-1 kinase, a receptor for vascular endothelial growth factor, had a tubulogenic activity not only in endothelial cells but also in fibroblastic cells. Here we show that tubulogenesis by BCR-FLTm1 depends on FAK and that FAK tyrosine phosphorylation and association with an activated Flt-1 receptor complex is increased after vascular endothelial growth factor stimulation of NIH3T3 cells overexpressing Flt-1.
Collapse
Affiliation(s)
- Y Maru
- Department of Genetics, Institute of Medical Science, University of tokyo, Japan.
| | | | | |
Collapse
|
105
|
Schaller MD. Biochemical signals and biological responses elicited by the focal adhesion kinase. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1540:1-21. [PMID: 11476890 DOI: 10.1016/s0167-4889(01)00123-9] [Citation(s) in RCA: 419] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The focal adhesion kinase, FAK, is an important component of an integrin-dependent signaling pathway, which functions to transmit signals from the extracellular matrix into the cytoplasm. FAK is an essential gene product, since the fak-/- mouse exhibits embryonic lethality. A number of important biological processes, including cell motility and cell survival, are controlled by integrin-dependent signals and FAK has been implicated in regulating these processes. This review will focus upon recent findings providing insight into the mechanisms by which FAK transmits biochemical signals and elicits biological effects.
Collapse
Affiliation(s)
- M D Schaller
- Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill 27599, USA.
| |
Collapse
|
106
|
Mazar AP. The urokinase plasminogen activator receptor (uPAR) as a target for the diagnosis and therapy of cancer. Anticancer Drugs 2001; 12:387-400. [PMID: 11395568 DOI: 10.1097/00001813-200106000-00001] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The identification and characterization of validated molecular targets for cancer drug and diagnostic development is rapidly changing the way that promising new anti-cancer compounds are developed and evaluated. A significant body of in vitro and in vivo data has established the urokinase plasminogen activator (uPA) system as a promising target for cancer drug development. The uPA system has been demonstrated to have pleiotropic activities in the development of tumors, and in tumor progression and angiogenesis. There are multiple ways to target this system, the most straightforward being the development of small molecule active site inhibitors of the serine protease, uPA. However, compounds of this type have not entered into clinical trials, and issues related to selectivity and specificity of this class of inhibitors have yet to be satisfactorily resolved. Recent evidence suggests that in addition to uPA, its specific cell surface receptor (uPAR) may also be a suitable target for the design and development of cancer therapeutic and diagnostic agents. uPAR is central to several pathways implicated in tumor progression and angiogenesis. The binding of the uPA zymogen (scuPA) to uPAR appears to be a pre-requisite for efficient cell-surface activation of scuPA to the active two-chain form (tcuPA) by plasmin, and simple ligand occupancy of uPAR by scuPA initiates various signaling pathways leading to alterations in cell motility and adhesion. One therapeutic rationale that is currently being investigated is the simple displacement of scuPA or tcuPA from suPAR, which may effectively inhibit both the proteolytic and signal-transducing cascades. In addition, other approaches to the modulation of the activity of this system that may also be useful include blocking the interaction of uPAR with integrins and extracellular matrix proteins as well as strategies to down-regulate the expression of uPA and uPAR in target cells. This review will summarize these approaches, and also describe the targeting of uPAR for diagnosis and imaging.
Collapse
Affiliation(s)
- A P Mazar
- Attenuon, L.L.C., 10130 Sorrento Valley Road, Suite B, San Diego, CA 92121, USA.
| |
Collapse
|
107
|
Weylandt KH, Valverde MA, Nobles M, Raguz S, Amey JS, Diaz M, Nastrucci C, Higgins CF, Sardini A. Human ClC-3 is not the swelling-activated chloride channel involved in cell volume regulation. J Biol Chem 2001; 276:17461-7. [PMID: 11278960 DOI: 10.1074/jbc.m011667200] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Volume regulation is essential for normal cell function. A key component of the cells' response to volume changes is the activation of a channel, which elicits characteristic chloride currents (I(Cl, Swell)). The molecular identity of this channel has been controversial. Most recently, ClC-3, a protein highly homologous to the ClC-4 and ClC-5 channel proteins, has been proposed as being responsible for I(Cl, Swell). Subsequently, however, other reports have suggested that ClC-3 may generate chloride currents with characteristics clearly distinct from I(Cl, Swell). Significantly different tissue distributions for ClC-3 have also been reported, and it has been suggested that two isoforms of ClC-3 may be expressed with differing functions. In this study we generated a series of cell lines expressing variants of ClC-3 to rigorously address the question of whether or not ClC-3 is responsible for I(Cl, Swell). The data demonstrate that ClC-3 is not responsible for I(Cl, Swell) and has no role in regulatory volume decrease, furthermore, ClC-3 is not activated by intracellular calcium and fails to elicit chloride currents under any conditions tested. Expression of ClC-3 was shown to be relatively tissue-specific, with high levels in the central nervous system and kidney, and in contrast to previous reports, is essentially absent from heart. This distribution is also inconsistent with the previous proposed role in cell volume regulation.
Collapse
Affiliation(s)
- K H Weylandt
- Medical Research Council Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital Campus, Du Cane Rd., London W12 0NN, United Kingdom
| | | | | | | | | | | | | | | | | |
Collapse
|
108
|
Degryse B, Orlando S, Resnati M, Rabbani SA, Blasi F. Urokinase/urokinase receptor and vitronectin/αvβ3 integrin induce chemotaxis and cytoskeleton reorganization through different signaling pathways. Oncogene 2001; 20:2032-43. [PMID: 11360187 DOI: 10.1038/sj.onc.1204261] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2000] [Revised: 01/05/2001] [Accepted: 01/15/2001] [Indexed: 11/09/2022]
Abstract
Vitronectin (VN) and pro-urokinase (pro-uPA) stimulated migration of rat smooth muscle cells in a dose-dependent and additive way, and induced motile-type changes in cell morphology together with a complete reorganization of the actin filaments and of the microtubules. All these effects were inhibited by pertussis toxin, or by antibodies directed against the urokinase receptor (uPAR) or against the VN receptor alpha(v)beta(3) suggesting that an association between the two receptors is required to mediate both signals. Investigation of the signaling pathways showed that increasing the intracellular cAMP resulted in a selective inhibition of VN-induced cell migration. On the other hand, PD 98059, an inhibitor of MEK, differentially inhibited the pro-uPA- but not the VN-induced cell migration. Phosphorylation and nuclear translocation of Erk by pro-uPA was directly observed. We conclude that the signaling pathways of pro-uPA and VN must be at least in part different.
Collapse
Affiliation(s)
- B Degryse
- Department of Molecular Pathology and Medicine, Università Vita-Salute San Raffaele, Via Olgettina 58, 20132 Milano, Italy
| | | | | | | | | |
Collapse
|
109
|
Kassis J, Lauffenburger DA, Turner T, Wells A. Tumor invasion as dysregulated cell motility. Semin Cancer Biol 2001; 11:105-17. [PMID: 11322830 DOI: 10.1006/scbi.2000.0362] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Investigations across a range of disciplines over the past decade have brought the study of cell motility and its role in invasion to an exciting threshold. The biophysical forces proximally involved in generating cell locomotion, as well as the underlying signaling and genomic regulatory processes, are gradually becoming elucidated. We now appreciate the intricacies of the many cellular and extracellular events that modulate cell migration. This has enabled the demonstration of a causal role of cell motility in tumor progression, with various points of 'dysregulation' of motility being responsible for promoting invasion. In this paper, we describe key fundamental principles governing cell motility and branch out to describe the essence of the data that describe these principles. It has become evident that many proposed models may indeed be converging into a tightly-woven tapestry of coordinated events which employ various growth factors and their receptors, adhesion receptors (integrins), downstream molecules, cytoskeletal components, and altered genomic regulation to accomplish cell motility. Tumor invasion occurs in response to dysregulation of many of these modulatory points; specific examples include increased signaling from the EGF receptor and through PLC gamma, altered localization and expression of integrins, changes in actin modifying proteins and increased transcription from specific promoter sites. This diversity of alterations all leading to tumor invasion point to the difficulty of correcting causal events leading to tumor invasion and rather suggest that the underlying common processes required for motility be targeted for therapeutic intervention.
Collapse
Affiliation(s)
- J Kassis
- Department of Pathology, University of Pittsburgh and Pittsburgh VAMC, 713 Scaife Hall, Pittsburgh, PA 15261, USA
| | | | | | | |
Collapse
|
110
|
Wang Y. The role and regulation of urokinase-type plasminogen activator receptor gene expression in cancer invasion and metastasis. Med Res Rev 2001; 21:146-70. [PMID: 11223863 DOI: 10.1002/1098-1128(200103)21:2<146::aid-med1004>3.0.co;2-b] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This article reviews the role of urokinase-type plasminogen activator receptor (uPAR) and its protein, mRNA, cDNA, genomic organization, promoter, transcription activation factors, and signal transduction. The uPAR has been implicated in several biological processes including angiogenesis, monocyte migration, cancer metastasis, trophoblast implantation, and wound healing. It is a specific cell surface receptor for its ligand uPA which catalyzes the formation of plasmin from plasminogen to generate the proteolytic cascade that contributes to the breakdown of extracellular matrix, a key step in cancer metastasis. The uPAR is a 55-60 kDa glycoprotein organized as three homologous cysteine-rich domains. It attaches to the plasma membrane via a covalent linkage to a glycosyl-phosphatidylinositol (GPI) moiety and appears to play an important role in transmembrane signalling. The 1.4-kb human uPAR cDNA and 21.23-kb genomic DNA have been cloned and the gene contains seven exons. The uPAR promoter region was defined in a 188 bp fragment between bases -141 and +47 relative to the transcription start site. Binding of transcription factors (Sp1, AP-2, NFkappaB and two AP-1) to the uPAR promoter region activates the basal transcription of the gene. There is a strong correlation between uPAR expression and the invasive cancer cell phenotype. uPAR may play a critical role in the process of cancer invasion and metastasis, as antisense uPAR mRNA can inhibit cancer spread in vitro and in vivo. These studies may provide a novel therapeutic target for blocking cancer invasion and metastasis.
Collapse
Affiliation(s)
- Y Wang
- Orthopaedic Research Institute, St George Hospital, University of New South Wales, Sydney, NSW 2145, Australia.
| |
Collapse
|
111
|
Webb DJ, Thomas KS, Gonias SL. Plasminogen activator inhibitor 1 functions as a urokinase response modifier at the level of cell signaling and thereby promotes MCF-7 cell growth. J Cell Biol 2001; 152:741-52. [PMID: 11266465 PMCID: PMC2195772 DOI: 10.1083/jcb.152.4.741] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Plasminogen activator inhibitor 1 (PAI-1) is a major inhibitor of urokinase-type plasminogen activator (uPA). In this study, we explored the role of PAI-1 in cell signaling. In MCF-7 cells, PAI-1 did not directly activate the mitogen-activated protein (MAP) kinases, extracellular signal-regulated kinase (ERK) 1 and ERK2, but instead altered the response to uPA so that ERK phosphorylation was sustained. This effect required the cooperative function of uPAR and the very low density lipoprotein receptor (VLDLr). When MCF-7 cells were treated with uPA-PAI-1 complex in the presence of the VLDLr antagonist, receptor-associated protein, or with uPA-PAI-1(R76E) complex, which binds to the VLDLr with greatly decreased affinity, transient ERK phosphorylation (<5 min) was observed, mimicking the uPA response. ERK phosphorylation was not induced by tissue-type plasminogen activator-PAI-1 complex or by uPA-PAI-1 complex in the presence of antibodies that block uPA binding to uPAR. uPA-PAI-1 complex induced tyrosine phosphorylation of focal adhesion kinase and Shc and sustained association of Sos with Shc, whereas uPA caused transient association of Sos with Shc. By sustaining ERK phosphorylation, PAI-1 converted uPA into an MCF-7 cell mitogen. This activity was blocked by receptor-associated protein and not observed with uPA-PAI-1(R76E) complex, demonstrating the importance of the VLDLr. uPA promoted the growth of other cells in which ERK phosphorylation was sustained, including beta3 integrin overexpressing MCF-7 cells and HT 1080 cells. The MEK inhibitor, PD098059, blocked the growth-promoting activity of uPA and uPA-PAI-1 complex in these cells. Our results demonstrate that PAI-1 may regulate uPA-initiated cell signaling by a mechanism that requires VLDLr recruitment. The kinetics of ERK phosphorylation in response to uPAR ligation determine the function of uPA and uPA-PAI-1 complex as growth promoters.
Collapse
Affiliation(s)
- D J Webb
- Department of Pathology, and Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | | | | |
Collapse
|
112
|
Ossowski L, Aguirre-Ghiso JA. Urokinase receptor and integrin partnership: coordination of signaling for cell adhesion, migration and growth. Curr Opin Cell Biol 2000; 12:613-20. [PMID: 10978898 DOI: 10.1016/s0955-0674(00)00140-x] [Citation(s) in RCA: 299] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Urokinase-type plasminogen activator receptor (uPAR) binds the urokinase-type plasminogen activator (uPA) and facilitates a proteolytic cascade focused at the cell surface. More recently, uPAR was recognized as a multifunctional protein that, through its interactions with integrins, initiates signaling events that alter cell adhesion, migration and proliferation. Results obtained recently have led to new insights into the structural aspects of uPAR interaction with integrins, provided a more detailed description of the signaling pathway they induce, and determined that uPAR signaling plays a role in cell migration and tumorigenicity.
Collapse
Affiliation(s)
- L Ossowski
- Rochelle Belfer Chemotherapy Foundation, Division of Medical Oncology, Department of Medicine, Box 1178, Mount Sinai School of Medicine, New York, New York 11029, USA.
| | | |
Collapse
|