101
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Tonegawa A, Kasai T, Takahashi Y. Systematic screening for signaling molecules expressed during somitogenesis by the signal sequence trap method. Dev Biol 2003; 262:32-50. [PMID: 14512016 DOI: 10.1016/s0012-1606(03)00327-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We describe a systematic screening to search for molecules that act as an extracellular signal during somitogenesis in vertebrates. Somitogenesis, which gives rise to segmented structures of axial bones and muscles, is a consequence of cooperative morphogenetic movements caused by precisely regulated cell and tissue interactions. We employed a strategy that combined subtractive hybridization to enrich paraxial mesoderm/somite-specific cDNAs and the signal sequence trap method, which selects signal sequence-containing molecules. Ninety-two independent cDNAs found to possess a putative signal sequence or a transmembrane domain are presented with a data base accession number for each. These clones include cDNAs which were previously identified with a function characterized, cDNAs previously identified with an undetermined function, and also cDNAs with no similarity to known sequences. Among them, 16 clones exhibited peculiar patterns of expression in the presomitic mesoderm/somites revealed by whole-mount and section in situ hybridization techniques, with some clones also being expressed in the forming neural tube. This is the first report in which an elaborate strategy combining three different screening steps was employed to identify signaling molecules relevant to a particular morphogenetic process.
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Affiliation(s)
- Akane Tonegawa
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara, 630-0101, Japan
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102
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Hynes RO, Lively JC, McCarty JH, Taverna D, Francis SE, Hodivala-Dilke K, Xiao Q. The diverse roles of integrins and their ligands in angiogenesis. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2003; 67:143-53. [PMID: 12858535 DOI: 10.1101/sqb.2002.67.143] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- R O Hynes
- Howard Hughes Medical Institute, Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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103
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Alfandari D, Cousin H, Gaultier A, Hoffstrom BG, DeSimone DW. Integrin alpha5beta1 supports the migration of Xenopus cranial neural crest on fibronectin. Dev Biol 2003; 260:449-64. [PMID: 12921745 DOI: 10.1016/s0012-1606(03)00277-x] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
During early embryonic development, cranial neural crest cells emerge from the developing mid- and hindbrain. While numerous studies have focused on integrin involvement in trunk neural crest cell migration, comparatively little is known about mechanisms of cranial neural crest cell migration. We show that fibronectin, but not laminin, vitronectin, or type I collagen can support cranial neural crest cell migration and segmentation in vitro. These behaviors require both the RGD and "synergy" sites located within the central cell-binding domain of fibronectin. While these two sites are sufficient for cranial neural crest cell migration, we find that the second Heparin-binding domain of fibronectin can provide additional support for cranial neural crest cell migration in vitro. Finally, using a function blocking monoclonal antibody, we show that cranial neural crest cell migration on fibronectin requires the integrin alpha5beta1.
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Affiliation(s)
- Dominique Alfandari
- Department of Cell Biology, University of Virginia Health Sciences System, Box 800732, School of Medicine, Charlottesville, VA 22908, USA.
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104
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Yoshida N, Hishiyama S, Yamaguchi M, Hashiguchi M, Miyamoto Y, Kaminogawa S, Hisatsune T. Decrease in expression of alpha 5 beta 1 integrin during neuronal differentiation of cortical progenitor cells. Exp Cell Res 2003; 287:262-71. [PMID: 12837282 DOI: 10.1016/s0014-4827(03)00158-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Neuronal differentiation of embryonic neural progenitor cells is regulated by both intrinsic and extrinsic signals. Since dynamic changes in cell shape typify neuronal differentiation, cell adhesion molecules could be relevant to this process. Although it has been reported that fibronectin-integrin interactions are important for the proliferation of neural progenitor cells, little is known about the contribution of integrins to neuronal differentiation. In order to address this shortfall, we examined integrin expression on cortical progenitor cells by using immunohistochemistry and FACS analysis of cells in which GFP expression was driven by regulatory (promoter) regions of the nestin gene (nestin-GFP(+)). We here report that high levels of nestin promoter activity correlated with high expression levels of alpha(5)beta(1) integrin (alpha(5)beta(1)(high) cells). FACS analysis of nestin-GFP(+) cortical cells revealed an additional subpopulation with reduced expression of alpha(5)beta(1) integrin (alpha(5)beta(1)(low) cells). The size of the alpha(5)beta(1)(low) subpopulation increased during cortical development. To investigate the correlation between integrin and neuronal differentiation, nestin-GFP(+) cortical progenitor cells were sorted into alpha(5)beta(1)(high) or alpha(5)beta(1)(low) populations, and each potential to differentiate was analyzed. We show that the nestin-GFP(+) alpha(5)beta(1)(high) population corresponded to broadly multipotential neural progenitor cells, whereas nestin-GFP(+) alpha(5)beta(1)(low) cells appeared to be committed to a neuronal fate. These findings suggest that alpha(5)beta(1) expression on cortical progenitor cells is developmentally regulated and its downregulation is involved in the process of neuronal differentiation.
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Affiliation(s)
- Naoko Yoshida
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan
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105
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Pietri T, Thiery JP, Dufour S. Differential expression of beta3 integrin gene in chick and mouse cranial neural crest cells. Dev Dyn 2003; 227:309-13. [PMID: 12761858 DOI: 10.1002/dvdy.10299] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
RNA in situ hybridization on early chicken embryos revealed that the beta3 integrin gene started to be expressed after Hamburger and Hamilton (HH) stage 6 in the presumptive epidermis adjacent to the neural plate, before closure of the neural tube. The beta3 integrin gene was also strongly expressed in cephalic neural crest cells at the same stage in which they begin their migration but disappeared progressively in these cells along the route they take to the branchial arches. The gene was weakly expressed in the differentiating cranial neural crest cells. The alphaVbeta3 integrin protein complex was also mainly detected in the migratory cephalic neural crest cells. However, during early mouse embryogenesis and in contrast to the chick, the beta3 integrin gene was expressed in the foregut diverticulum and in the heart and not in the cephalic neural crest cells. Therefore, the difference in the beta3 integrin expression suggests that mouse and chicken cranial neural crest cells may have distinct integrin requirements during their ontogenesis.
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Affiliation(s)
- Thomas Pietri
- UMR 144 Compartimentation et Dynamique Cellulaire, Centre National de la Recherche Scientifique et Institut Curie, Paris, France
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106
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Hotchkiss KA, Ashton AW, Schwartz EL. Thymidine phosphorylase and 2-deoxyribose stimulate human endothelial cell migration by specific activation of the integrins alpha 5 beta 1 and alpha V beta 3. J Biol Chem 2003; 278:19272-9. [PMID: 12639965 DOI: 10.1074/jbc.m212670200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thymidine phosphorylase is an angiogenic factor that is frequently overexpressed in solid tumors, in rheumatoid arthritis, and in response to inflammatory cytokines. Our previous studies showed that cells expressing thymidine phosphorylase stimulated endothelial cell migration in vitro. This was a consequence of the intracellular metabolism of thymidine by thymidine phosphorylase and subsequent extracellular release of 2-deoxyribose. The mechanisms by which 2-deoxyribose might mediate thymidine phosphorylase-induced cell migration in vitro, however, are obscure. Here we show that both thymidine phosphorylase and 2-deoxyribose stimulated the formation of focal adhesions and the tyrosine 397 phosphorylation of focal adhesion kinase in human umbilical vein endothelial cells. Although similar actions occurred upon treatment with the angiogenic factor vascular endothelial growth factor (VEGF), thymidine phosphorylase differed from VEGF in that its effect on endothelial cell migration was blocked by antibodies to either integrin alpha 5 beta 1 or alpha v beta 3, whereas VEGF-induced endothelial cell migration was only blocked by the alpha v beta 3 antibody. Further, thymidine phosphorylase and 2-deoxyribose, but not VEGF, increased the association of both focal adhesion kinase and the focal adhesion-associated protein vinculin with integrin alpha 5 beta 1 and, in intact cells, increased the co-localization of focal adhesion kinase with alpha 5 beta 1. Thymidine phosphorylase and 2-deoxyribose-induced focal adhesion kinase phosphorylation was blocked by the antibodies to alpha 5 beta 1 and alpha v beta 3, directly linking the migration and signaling components of thymidine phosphorylase and 2-deoxyribose action. Cell surface expression of alpha 5 beta 1 was also increased by thymidine phosphorylase and 2-deoxyribose. These experiments are the first to demonstrate a direct effect of thymidine phosphorylase and 2-deoxyribose on signaling pathways associated with endothelial cell migration.
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Affiliation(s)
- Kylie A Hotchkiss
- Department of Oncology, Albert Einstein College of Medicine, Bronx, New York 10467, USA
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107
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Chao HHJ, Mentzer SE, Schimenti JC, You Y. Overlapping deletions define novel embryonic lethal loci in the mouse t complex. Genesis 2003; 35:133-42. [PMID: 12533796 DOI: 10.1002/gene.10174] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
SUMMARY The t complex region of mouse chromosome 17 contains genetic information critical for embryonic development. To identify and map loci required for normal embryogenesis, a set of overlapping deletions (D17Aus9(df10J), D17Aus9(df12J), and D17Aus9(df13J)) surrounding the D17Aus9 locus and one encompassing the T locus, Del(17)T(7J), were bred in various combinations and the consequences of nullizygosity in overlapping regions were examined. The results indicated that there are at least two functional units within 1 cM of D17Aus9. l17J1 is a peri-implantation lethal mutation within the region deleted in D17Aus9(df13J), whereas l17J2 is a later-acting lethal defined by the region of overlap between Del(17)T(7J) and D17Aus9(df12J). Del(17)T(7J)/D17Aus9(df12J) embryos die around 10.5 dpc. The development of the mutant embryos is characterized by lack of axial rotation, an abnormal notochord structure, and a ballooning pericardium. These studies demonstrate the value of overlapping deletion complexes, as opposed to individual deletion complexes, for the identification, mapping, and analysis of genes required for embryonic development.
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Affiliation(s)
- Hanna H J Chao
- Life Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6445, USA
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108
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Li F, Redick SD, Erickson HP, Moy VT. Force measurements of the alpha5beta1 integrin-fibronectin interaction. Biophys J 2003; 84:1252-62. [PMID: 12547805 PMCID: PMC1302701 DOI: 10.1016/s0006-3495(03)74940-6] [Citation(s) in RCA: 248] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2002] [Accepted: 09/30/2002] [Indexed: 12/27/2022] Open
Abstract
The interaction of the alpha(5)beta(1) integrin and its ligand, fibronectin (FN), plays a crucial role in the adhesion of cells to the extracellular matrix. An important intrinsic property of the alpha(5)beta(1)/FN interaction is the dynamic response of the complex to a pulling force. We have carried out atomic force microscopy measurements of the interaction between alpha(5)beta(1) and a fibronectin fragment derived from the seventh through tenth type III repeats of FN (i.e., FN7-10) containing both the arg-gly-asp (RGD) sequence and the synergy site. Direct force measurements obtained from an experimental system consisting of an alpha(5)beta(1) expressing K562 cell attached to the atomic force microscopy cantilever and FN7-10 adsorbed on a substrate were used to determine the dynamic response of the alpha(5)beta(1)/FN7-10 complex to a pulling force. The experiments were carried out over a three-orders-of-magnitude change in loading rate and under conditions that allowed for detection of individual alpha(5)beta(1)/FN7-10 interactions. The dynamic rupture force of the alpha(5)beta(1)/FN7-10 complex revealed two regimes of loading: a fast loading regime (>10,000 pN/s) and a slow loading regime (<10,000 pN/s) that characterize the inner and outer activation barriers of the complex, respectively. Activation by TS2/16 antibody increased both the frequency of adhesion and elevated the rupture force of the alpha(5)beta(1)/wild type FN7-10 complex to higher values in the slow loading regime. In experiments carried out with a FN7-10 RGD deleted mutant, the force measurements revealed that both inner and outer activation barriers were suppressed by the mutation. Mutations to the synergy site of FN, however, suppressed only the outer barrier activation of the complex. For both the RGD and synergy deletions, the frequency of adhesion was less than that of the wild type FN7-10, but was increased by integrin activation. The rupture force of these mutants was only slightly less than that of the wild type, and was not increased by activation. These results suggest that integrin activation involved a cooperative interaction with both the RGD and synergy sites.
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Affiliation(s)
- Feiya Li
- Department of Physiology and Biophysics, University of Miami School of Medicine, Miami, Florida 33136, USA
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109
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Kim S, Bakre M, Yin H, Varner JA. Inhibition of endothelial cell survival and angiogenesis by protein kinase A. J Clin Invest 2002. [DOI: 10.1172/jci0214268] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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110
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Klein S, de Fougerolles AR, Blaikie P, Khan L, Pepe A, Green CD, Koteliansky V, Giancotti FG. Alpha 5 beta 1 integrin activates an NF-kappa B-dependent program of gene expression important for angiogenesis and inflammation. Mol Cell Biol 2002; 22:5912-22. [PMID: 12138201 PMCID: PMC133962 DOI: 10.1128/mcb.22.16.5912-5922.2002] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
GeneCalling, a genome-wide method of mRNA profiling, reveals that endothelial cells adhering to fibronectin through the alpha 5 beta 1 integrin, but not to laminin through the alpha 2 beta 1 integrin, undergo a complex program of gene expression. Several of the genes identified are regulated by the NF-kappa B transcription factor, and many are implicated in the regulation of inflammation and angiogenesis. Adhesion of endothelial cells to fibronectin activates NF-kappa B through a signaling pathway requiring Ras, phosphatidylinositol 3-kinase, and Rho family proteins, whereas adhesion to laminin has a limited effect. Retroviral transfer of the superrepressor of NF-kappa B, I kappa B-2A, blocks basic fibroblast growth factor-induced angiogenesis in vivo. These results suggest that engagement of the alpha 5 beta 1 integrin promotes an NF-kappa B-dependent program of gene expression that coordinately regulates angiogenesis and inflammation.
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Affiliation(s)
- Sharon Klein
- Cellular Biochemistry and Biophysics Program, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA
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111
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Peters J, Sechrist J, Luetolf S, Loredo G, Bronner-Fraser M. Spatial expression of the alternatively spliced EIIIB and EIIIA segments of fibronectin in the early chicken embryo. CELL COMMUNICATION & ADHESION 2002; 9:221-38. [PMID: 12699090 DOI: 10.1080/15419060216015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Using domain-specific antibodies, we have analyzed the tissue distribution of fibronectins (FNs) containing the alternatively spliced EIIIB and EIIIA segments relative to total FN in early chicken embryos. The results show a selective loss of EIIIA+ FN staining in the notochordal sheath and in cartilaginous structures between 4.5 and 7.0 days of development. In other regions, EIIIB+ and EIIIA+ FNs are extensively codistributed in and around mesoderm-derived structures (somites, notochord, heart, and blood vessels), in basal laminae of endoderm and ectoderm-derived structures, as well as within the vicinity of neural crest formation and migration. We also noted that EIIIA staining overlaps with spatial patterns of distribution that have previously been described for the alpha4 integrin subunit, a component of the EIIIA receptor alpha4beta1.
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Affiliation(s)
- John Peters
- Sacramento VA Medical Center, VA Northern California Health Care System, Mather, CA 95655, USA.
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112
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Francis SE, Goh KL, Hodivala-Dilke K, Bader BL, Stark M, Davidson D, Hynes RO. Central roles of alpha5beta1 integrin and fibronectin in vascular development in mouse embryos and embryoid bodies. Arterioscler Thromb Vasc Biol 2002; 22:927-33. [PMID: 12067900 DOI: 10.1161/01.atv.0000016045.93313.f2] [Citation(s) in RCA: 224] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Vascular development and maturation are dependent on the interactions of endothelial cell integrins with surrounding extracellular matrix. Previous investigations of the primacy of certain integrins in vascular development have not addressed whether this could also be a secondary effect due to poor embryonic nutrition. Here, we show that the alpha5 integrin subunit and fibronectin have critical roles in blood vessel development in mouse embryos and in embryoid bodies (EBs) differentiated from embryonic stem cells (a situation in which there is no nutritional deficit caused by the mutations). In contrast, vascular development in vivo and in vitro is not strongly dependent on alpha(v) or beta3 integrin subunits. In mouse embryos lacking alpha5 integrin, greatly distended blood vessels are seen in the vitelline yolk sac and in the embryo itself. Additionally, overall blood vessel pattern complexity is reduced in alpha5-null tissues. This defective vascular phenotype is correlated with a decrease in the ligand for alpha5 integrin, fibronectin (FN), in the endothelial basement membranes. A striking and significant reduction in early capillary plexus formation and maturation was apparent in EBs formed from embryonic stem cells lacking alpha5 integrin or FN compared with wild-type EBs or EBs lacking alpha(v) or beta3 integrin subunits. Vessel phenotype could be partially restored to FN-null EBs by the addition of whole FN to the culture system. These findings confirm a clear role for alpha5 and FN in early blood vessel development not dependent on embryo nutrition or alpha(v) or beta3 integrin subunits. Thus, successful early vasculogenesis and angiogenesis require alpha5-FN interactions.
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MESH Headings
- Animals
- Blood Vessels/embryology
- Blood Vessels/pathology
- Blood Vessels/physiology
- Cell Differentiation/genetics
- Cells, Cultured
- Embryo, Mammalian/blood supply
- Embryo, Mammalian/pathology
- Embryo, Mammalian/physiology
- Embryonic Structures/blood supply
- Embryonic Structures/pathology
- Embryonic Structures/physiology
- Endothelium, Vascular/embryology
- Endothelium, Vascular/pathology
- Endothelium, Vascular/physiology
- Mice
- Phenotype
- Platelet Endothelial Cell Adhesion Molecule-1/metabolism
- Receptors, Fibronectin/biosynthesis
- Receptors, Fibronectin/deficiency
- Receptors, Fibronectin/genetics
- Receptors, Fibronectin/physiology
- Stem Cells/chemistry
- Stem Cells/pathology
- Stem Cells/physiology
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Affiliation(s)
- Sheila E Francis
- Cardiovascular Research Group, University of Sheffield, Sheffield, UK.
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113
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Abstract
In vertebrates, the paraxial mesoderm corresponds to the bilateral strips of mesodermal tissue flanking the notochord and neural tube and which are delimited laterally by the intermediate mesoderm and the lateral plate. The paraxial mesoderm comprises the head or cephalic mesoderm anteriorly and the somitic region throughout the trunk and the tail of the vertebrates. Soon after gastrulation, the somitic region of vertebrates starts to become segmented into paired blocks of mesoderm, termed somites. This process lasts until the number of somites characteristic of the species is reached. The somites later give rise to all skeletal muscles of the body, the axial skeleton, and part of the dermis. In this review I discuss the processes involved in the formation of the paraxial mesoderm and its segmentation into somites in vertebrates.
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Affiliation(s)
- O Pourquié
- Laboratoire de génétique et de physiologie du développement, Developmental Biology Institute of Marseille (IBDM), CNRS-INSERM-Université de la méditerranée-AP de Marseille, France.
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114
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Urbich C, Dernbach E, Reissner A, Vasa M, Zeiher AM, Dimmeler S. Shear stress-induced endothelial cell migration involves integrin signaling via the fibronectin receptor subunits alpha(5) and beta(1). Arterioscler Thromb Vasc Biol 2002; 22:69-75. [PMID: 11788463 DOI: 10.1161/hq0102.101518] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Endothelial cell (EC) migration is required for angiogenesis, neovascularization, and reendothelialization. Integrins, known as alphabeta-heterodimeric cell-surface receptors, regulate cell migration and are essential for mechanotransduction of hemodynamic forces. Therefore, we investigated the effect of shear stress on EC migration and the contribution of the integrins and integrin-dependent signaling pathways in a scratched-wound assay. Laminar shear stress-induced EC migration was significantly reduced by integrin-receptor blocking with RGD peptides or with neutralizing antibodies against integrin subunits alpha(5) and beta(1), whereas antibodies against alpha(v)beta(3) or alpha(2)beta(1) had no effect. Cell-surface levels of the integrin alpha(5) and beta(1) were specifically upregulated in migrating ECs at the wound edges. Consistent with the important role of integrins for shear stress-increased cell migration, blockade of the integrin-associated adapter protein Shc by overexpression of dominant negative construct inhibited shear stress-stimulated EC migration. Moreover, pharmacological inhibition of the integrin downstream effector signaling molecules ERK1/2 or phosphatidyl-inositol-3-kinase prevented shear stress-induced EC migration. In contrast, inhibition of the NO synthase had no effect. Taken together, our results indicate that laminar shear stress enhances EC migration via the fibronectin receptor subunits alpha(5) and beta(1), which serve as central mechanotransducers in ECs. Shear stress-induced enhancement of EC migration might contribute importantly to accelerated reendothelialization of denuded arteries.
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Affiliation(s)
- Carmen Urbich
- Molecular Cardiology, Department of Internal Medicine IV, University of Frankfurt, Frankfurt, Germany
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115
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Abstract
Crosstalk between integrins and growth factor receptors are an important signaling mechanism to provide specificity during normal development and pathological processes in vascular biology. Evidence from several model systems demonstrates the physiological importance of the coordination of signals from growth factors and the extracellular matrix to support cell proliferation, migration, and invasion in vivo. Several examples of crosstalk between these two important classes of receptors indicate that integrin ligation is required for growth factor-induced biological processes. Furthermore, integrins can directly associate with growth factor receptors, thereby regulating the capacity of integrin/growth factor receptor complexes to propagate downstream signaling. Recent data suggest that antagonists of alpha(v) integrins can provide a therapeutic benefit in human cancer patients, whereas knockout mice lacking specific integrins can provide an interesting insight into the role of integrins during development. This review will focus on the biological importance of integrin and growth factor receptor crosstalk that occurs during cell growth, migration, and invasion as well as in endothelial cells during angiogenesis.
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Affiliation(s)
- B P Eliceiri
- Scripps Research Institute, La Jolla, California, USA.
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116
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Testaz S, Duband JL. Central role of the alpha4beta1 integrin in the coordination of avian truncal neural crest cell adhesion, migration, and survival. Dev Dyn 2001; 222:127-40. [PMID: 11668592 DOI: 10.1002/dvdy.1181] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Based on functional and histological studies, the fibronectin receptor of the integrin family alpha4beta1 has been ascribed a critical role during neural crest cell migration in the vertebrate embryo. In the present study, because integrins have been shown to participate in multiple basic cellular processes, including cell adhesion, migration, survival, proliferation, and differentiation, we have reexamined in detail the role of alpha4beta1 during avian truncal neural crest cell migration. RT-PCR and immunocytochemical studies revealed that migrating neural crest cells but not premigratory cells explanted in vitro expressed detectable levels of alpha4 messengers and proteins suggesting that alpha4beta1 expression was induced at the time of the initiation of the migration phase. In agreement with this observation, antibody inhibition of alpha4beta1 activity in vitro resulted in a strong, immediate and sustained reduction of neural crest cell motion on fibronectin, as judged on videomicroscopy analyses, but apparently did not prevent their delamination from the neural tube. However, alpha4beta1 appeared to exhibit a broader role in the control of cell migration on a variety of extracellular matrix molecules, presumably by regulating cellular events downstream from integrins. Moreover, blocking alpha4beta1 function caused a severe increase in apoptotic cell death among the neural crest population without influencing notably cell proliferation. Collectively, these results indicate that, notwithstanding its critical implication in cell motion, alpha4beta1 integrin could play a central role in neural crest cell development by coordinating multiple cellular events, such as cell adhesion, locomotion, and survival.
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Affiliation(s)
- S Testaz
- Laboratoire de Biologie du Développement, CNRS UMR 7622, Université Pierre et Marie Curie, 9 quai Saint Bernard, 7éme etage, 75005 Paris, France
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117
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Abstract
Recent work from several laboratories indicates that the coordination of endothelial cell adhesion events with growth factor receptor inputs regulates endothelial cell responses during angiogenesis. Analyses of the signaling pathways downstream of integrins, cadherins and growth-factor receptors are providing an insight into the molecular basis of known anti-angiogenic strategies, as well as into the design of novel therapies.
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Affiliation(s)
- B P Eliceiri
- The Scripps Research Institute, IMM-24, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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118
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Bouvard D, Brakebusch C, Gustafsson E, Aszódi A, Bengtsson T, Berna A, Fässler R. Functional consequences of integrin gene mutations in mice. Circ Res 2001; 89:211-23. [PMID: 11485971 DOI: 10.1161/hh1501.094874] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Integrins are cell-surface receptors responsible for cell attachment to extracellular matrices and to other cells. The application of mouse genetics has significantly increased our understanding of integrin function in vivo. In this review, we summarize the phenotypes of mice carrying mutant integrin genes and compare them with phenotypes of mice lacking the integrin ligands.
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Affiliation(s)
- D Bouvard
- Department of Experimental Pathology, Lund University, Lund, Sweden.
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119
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Cillo C, Cantile M, Faiella A, Boncinelli E. Homeobox genes in normal and malignant cells. J Cell Physiol 2001; 188:161-9. [PMID: 11424082 DOI: 10.1002/jcp.1115] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Homeobox genes are transcription factors primarily involved in embryonic development. Several homeobox gene families have so far been identified: Hox, EMX, PAX, MSX as well as many isolated divergent homeobox genes. Among these, Hox genes are most intriguing for having a regulatory network structure organization. Recent indications suggest the involvement of homeobox genes in (i) crucial adult eukariotic cell functions and (ii) human diseases, spanning from diabetes to cancer. In this review we will discuss the mechanisms through which homeobox genes act, and will propose a model for the function of the Hox gene network as decoding system for achieving specific genetic programs. New technologies for whole-genome RNA expression will be crucial to evaluate the clinical relevance of homeobox genes in structural and metabolic diseases.
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Affiliation(s)
- C Cillo
- Department of Clinical and Experimental Medicine, Federico II University Medical School, Naples, Italy.
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120
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Saxton TM, Cheng AM, Ong SH, Lu Y, Sakai R, Cross JC, Pawson T. Gene dosage-dependent functions for phosphotyrosine-Grb2 signaling during mammalian tissue morphogenesis. Curr Biol 2001; 11:662-70. [PMID: 11369229 DOI: 10.1016/s0960-9822(01)00198-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND The mammalian Grb2 adaptor protein binds pTyr-X-Asn motifs through its SH2 domain, and engages downstream targets such as Sos1 and Gab1 through its SH3 domains. Grb2 thereby couples receptor tyrosine kinases to the Ras-MAP kinase pathway, and potentially to phosphatidylinositol (PI) 3'-kinase. By creating a null (Delta) allele of mouse Grb2, we have shown that Grb2 is required for endoderm differentiation at embryonic day 4.0. RESULTS Grb2 likely has multiple embryonic and postnatal functions. To address this issue, a hypomorphic mutation, first characterized in the Caenorhabditis elegans Grb2 ortholog Sem-5, was engineered into the mouse Grb2 gene. This mutation (E89K) reduces phosphotyrosine binding by the SH2 domain. Embryos that are compound heterozygous for the null and hypomorphic alleles exhibit defects in placental morphogenesis and in the survival of a subset of migrating neural crest cells required for branchial arch formation. Furthermore, animals homozygous for the hypomorphic mutation die perinatally because of clefting of the palate, a branchial arch-derived structure. Analysis of E89K/Delta Grb2 mutant fibroblasts revealed a marked defect in ERK/MAP kinase activation and Gab1 tyrosine phosphorylation following growth factor stimulation. CONCLUSIONS We have created an allelic series within mouse Grb2, which has revealed distinct functions for phosphotyrosine-Grb2 signaling in tissue morphogenesis and cell viability necessary for mammalian development. The placental defects in E89K/Delta mutant embryos are reminiscent of those seen in receptor tyrosine kinase-, Sos1-, and Gab1-deficient embryos, consistent with the finding that endogenous Grb2 is required for efficient RTK signaling to the Ras-MAP kinase and Gab1 pathways.
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Affiliation(s)
- T M Saxton
- Programme in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Ontario, M5G 1X5, Toronto, Canada
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121
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Abstract
BACKGROUND There is no universally accepted theory to explain esophageal embryology and the abnormal development that produces esophageal atresia. METHODS The impact of Adriamycin administration on the pathogenesis of esophageal atresia was studied in the rat model of VATER association, from embryonic day (ED) 10 to ED 13. RESULTS Tissues in the ED10 Adriamycin-exposed embryos displayed less cell proliferation as shown by the reduced population of MIB-5-labelled cells. Cell apoptosis that is characteristic of the normal ED 12 lateral epithelial folds of the foregut (the prospective site of tracheoesophageal septation) was absent in the foregut of the Adriamycin-exposed embryo. Histologic examination of the ED 11-exposed embryo showed the presence of abnormal notochord that was stretched, split, or tethered to the foregut. This contrasts with the normal embryo in which the notochord was localized in close vicinity of the ventral part of the neural tube and separated from the foregut by ample amount of mesenchyme. The abnormal localization of the notochord was accompanied by the lack of down-regulation of the sonic hedgehog (Shh) activity in the prospective site of future tracheoesophageal separation in the exposed ED 12 embryo. CONCLUSION The authors proposed that the ectopic location of the notochord leads to the disruption in Shh signalling that may underpin the development of esophageal atresia.
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Affiliation(s)
- J Orford
- Department of Surgical Research, Royal Alexandra Hospital for Children, Westmead, and the Department of Paediatrics and Child Health, University of Sydney, Sydney, and the Embryology Unit, Children's Medical Research Institute, Westmead, NSW, Australia
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122
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Abstract
The placenta is the first organ to form during mammalian embryogenesis. Problems in its formation and function underlie many aspects of early pregnancy loss and pregnancy complications in humans. Because the placenta is critical for survival, it is very sensitive to genetic disruption, as reflected by the ever-increasing list of targeted mouse mutations that cause placental defects. Recent studies of mouse mutants with disrupted placental development indicate that signalling interactions between the placental trophoblast and embryonic cells have a key role in placental morphogenesis. Furthering our understanding of mouse trophoblast development should provide novel insights into human placental function.
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Affiliation(s)
- J Rossant
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5.
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123
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Previtali SC, Feltri ML, Archelos JJ, Quattrini A, Wrabetz L, Hartung H. Role of integrins in the peripheral nervous system. Prog Neurobiol 2001; 64:35-49. [PMID: 11250061 DOI: 10.1016/s0301-0082(00)00045-9] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Integrins, a subgroup of adhesion receptors, are transmembrane glycoproteins that mediate interactions between cytoplasm and the extracellular environment. These interactions influence, among others, events such as cell migration, proliferation, and differentiation. Differential expression of integrins is developmentally regulated in the peripheral nervous system (PNS) and is associated with crucial events in both physiological and pathological processes. Preliminary studies suggest that integrin expression influences neural crest cell migration, axonal outgrowth, and Schwann cell differentiation. Similarly, the abnormal expression of integrins or their ligands, is associated with degenerative, inflammatory, and malignant disorders of the PNS. Finally, integrins participate in the complex interactions that promote repair of the PNS. A better comprehension of the role of integrins in the PNS, their protein interactions and transducing signals is being achieved by selected biochemical and genetic experiments. Here we review a large bias of evidence suggesting the key functions for integrins in the PNS.
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Affiliation(s)
- S C Previtali
- Department of Neurosciences and DIBIT, S. Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy.
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124
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Xue Y, Wang X, Li Z, Gotoh N, Chapman D, Skolnik EY. Mesodermal patterning defect in mice lacking the Ste20 NCK interacting kinase (NIK). Development 2001; 128:1559-72. [PMID: 11290295 DOI: 10.1242/dev.128.9.1559] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
We have previously shown that the Drosophila Ste20 kinase encoded by misshapen (msn) is an essential gene in Drosophila development. msn function is required to activate the Drosophila c-Jun N-terminal kinase (JNK), basket (Bsk), to promote dorsal closure of the Drosophila embryo. Later in development, msn expression is required in photoreceptors in order for their axons to project normally. A mammalian homolog of msn, the NCK-interacting kinase (NIK) (recently renamed to mitogen-activated protein kinase kinase kinase kinase 4; Map4k4), has been shown to activate JNK and to bind the SH3 domains of the SH2/SH3 adapter NCK. To determine whether NIK also plays an essential role in mammalian development, we created mice deficient in NIK by homologous recombination at the Nik gene. Nik(−/−) mice die postgastrulation between embryonic day (E) 9.5 and E10.5. The most striking phenotype in Nik(−/−) embryos is the failure of mesodermal and endodermal cells that arise from the anterior end of the primitive streak (PS) to migrate to their correct location. As a result Nik(−/−)embryos fail to develop somites or a hindgut and are truncated posteriorly. Interestingly, chimeric analysis demonstrated that NIK has a cell nonautonomous function in stimulating migration of presomitic mesodermal cells away from the PS and a second cell autonomous function in stimulating the differentiation of presomitic mesoderm into dermomyotome. These findings indicate that despite the large number of Ste20 kinases in mammalian cells, members of this family play essential nonredundant function in regulating specific signaling pathways. In addition, these studies provide evidence that the signaling pathways regulated by these kinases are diverse and not limited to the activation of JNK because mesodermal and somite development are not perturbed in JNK1-, and JNK2-deficient mice.
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Affiliation(s)
- Y Xue
- New York University Medical Center, Skirball Institute of Biomolecular Medicine, Department of Pharmacology, NY, NY10016, USA
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125
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Haack H, Hynes RO. Integrin receptors are required for cell survival and proliferation during development of the peripheral glial lineage. Dev Biol 2001; 233:38-55. [PMID: 11319856 DOI: 10.1006/dbio.2001.0213] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Proliferation and survival of Schwann cells are important for nerve development and for disease processes in peripheral nerves. We have analyzed embryos lacking alpha4- or alpha5-integrins and show here that these integrins contribute to the control of glial cell numbers. To overcome early embryonic lethality an explant and grafting system that allows the study of isolated glial progenitor cells both in vitro and in vivo was used. Schwann cells differentiate in the absence of alpha5 but their numbers and the proliferation rate of early progenitor cells are reduced, suggesting that alpha5 is essential for normal proliferation. Survival, rather than proliferation, is compromised in alpha4-deficient explants. Conditional immortalization allowed further characterization and revealed that alpha4 contributes to survival in a cell-density-dependent fashion. In addition, transplants into chicken embryos were used to analyze in vivo cell migration and showed that cell death occurs mainly in highly motile, individually migrating cells. The cell death patterns in vitro and in vivo argue that alpha4-integrins play a role in survival during cell migration. Neural crest migration has been suggested to require these integrins; however, no defects in migration were observed in the absence of alpha4 or alpha5. We conclude that integrins can complement growth factors in the control of glial cell numbers.
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Affiliation(s)
- H Haack
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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126
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Kim S, Harris M, Varner JA. Regulation of integrin alpha vbeta 3-mediated endothelial cell migration and angiogenesis by integrin alpha5beta1 and protein kinase A. J Biol Chem 2000; 275:33920-8. [PMID: 10944524 DOI: 10.1074/jbc.m003668200] [Citation(s) in RCA: 177] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recent studies indicate that angiogenesis depends, in part, on ligation of integrin alpha(5)beta(1) by fibronectin. Evidence is now provided that integrin alpha(5)beta(1) regulates the function of integrin alpha(v)beta(3) on endothelial cells during their migration in vitro or angiogenesis in vivo. Secretion of fibronectin by endothelial cells leads to the ligation of integrin alpha(5)beta(1), which potentiates alpha(v)beta(3)-mediated migration on vitronectin without influencing alpha(v)beta(3)-mediated cell adhesion. Endothelial cell attachment to vitronectin suppresses protein kinase A (PKA) activity, while addition of soluble anti-alpha(5)beta(1) restores this activity. Moreover, agents that activate intracellular PKA, such as forskolin, dibutyryl cAMP or alpha(5)beta(1) antagonists, suppress endothelial cell migration on vitronectin in vitro or angiogenesis in vivo. In contrast, inhibitors of PKA reverse the anti-migratory or anti-angiogenic effects mediated by alpha(5)beta(1) antagonists. Therefore, alpha(v)beta(3)-mediated endothelial cell migration and angiogenesis can be regulated by PKA activity, which depends on the ligation state of integrin alpha(5)beta(1).
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Affiliation(s)
- S Kim
- Cancer Center, University of California, San Diego, La Jolla, California 92093-0912, USA
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127
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Kim S, Bell K, Mousa SA, Varner JA. Regulation of angiogenesis in vivo by ligation of integrin alpha5beta1 with the central cell-binding domain of fibronectin. THE AMERICAN JOURNAL OF PATHOLOGY 2000; 156:1345-62. [PMID: 10751360 PMCID: PMC1876892 DOI: 10.1016/s0002-9440(10)65005-5] [Citation(s) in RCA: 467] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Angiogenesis depends on the cooperation of growth factors and cell adhesion events. Although alphav integrins have been shown to play critical roles in angiogenesis, recent studies in alphav-null mice suggest that other adhesion receptors and their ligands also regulate this process. Evidence is now provided that the integrin alpha5beta1 and its ligand fibronectin are coordinately up-regulated on blood vessels in human tumor biopsies and play critical roles in angiogenesis, resulting in tumor growth in vivo. Angiogenesis induced by multiple growth factors in chick embryos was blocked by monoclonal antibodies to the cell-binding domain of fibronectin. Furthermore, application of fibronectin or a proteolytic fragment of fibronectin containing the central cell-binding domain to the chick chorioallantoic membrane enhanced angiogenesis in an integrin alpha5beta1-dependent manner. Importantly, antibody, peptide, and novel nonpeptide antagonists of integrin alpha5beta1 blocked angiogenesis induced by several growth factors but had little effect on angiogenesis induced by vascular endothelial growth factor (VEGF) in both chick embryo and murine models. In fact, these alpha5beta1 antagonists inhibited tumor angiogenesis, thereby causing regression of human tumors in animal models. Thus, fibronectin and integrin alpha5beta1, like integrin alphavbeta3, contribute to an angiogenesis pathway that is distinct from VEGF-mediated angiogenesis, yet important for the growth of tumors.
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Affiliation(s)
- S Kim
- Department of Medicine/Cancer Center, Cellular and Molecular Medicine East, University of California San Diego, La Jolla, California 92093-0684, USA
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128
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Testaz S, Delannet M, Duband J. Adhesion and migration of avian neural crest cells on fibronectin require the cooperating activities of multiple integrins of the (beta)1 and (beta)3 families. J Cell Sci 1999; 112 ( Pt 24):4715-28. [PMID: 10574719 DOI: 10.1242/jcs.112.24.4715] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Based on genetic, functional and histological studies, the extracellular matrix molecule fibronectin has been proposed to play a key role in the migration of neural crest cells in the vertebrate embryo. In the present study, we have analyzed in vitro the repertoire and function of integrin receptors involved in the adhesive and locomotory responses of avian truncal neural crest cells to fibronectin. Immunoprecipitation experiments showed that neural crest cells express multiple integrins, namely (alpha)3(beta)1, (alpha)4(beta)1, (alpha)5(beta)1, (alpha)8(beta)1, (alpha)v(beta)1, (alpha)v(beta)3 and a (beta)8 integrin, as potential fibronectin receptors, and flow cytometry analyses revealed no major heterogeneity among the cell population for expression of integrin subunits. In addition, the integrin repertoire expressed by neural crest cells was found not to change dramatically during migration. At the cellular level, only (alpha)v(beta)1 and (alpha)v(beta)3 were concentrated in focal adhesion sites in connection with the actin microfilaments, whereas the other integrins were predominantly diffuse over the cell surface. In inhibition assays with function-perturbing antibodies, it appeared that complete abolition of cell spreading and migration could be achieved only by blocking multiple integrins of the (beta)1 and (beta)3 families, suggesting possible functional compensations between different integrins. In addition, these studies provided evidence for functional partitioning of integrins in cell adhesion and migration. While spreading was essentially mediated by (alpha)v(beta)1 and (alpha)8(beta)1, migration involved primarily (alpha)4(beta)1, (alpha)v(beta)3 and (alpha)8(beta)1 and, more indirectly, (alpha)3(beta)1. (alpha)5(beta)1 and the (beta)8 integrin were not found to play any major role in either adhesion or migration. Finally, consistent with the results of inhibition experiments, recruitment of (alpha)4(beta)1 and (alpha)v(beta)3, individually or in combination using antibodies or recombinant VCAM-1 and PECAM-1 molecules as a substratum, was required for migration but was not sufficient to produce migration of the cell population as efficiently as with fibronectin. In conclusion, our study indicates that neural crest cells express a multiplicity of fibronectin-binding integrins and suggests that dispersion of the cell population requires cooperation between distinct integrins regulating different events of cell adhesion, locomotion and, possibly, proliferation and survival.
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Affiliation(s)
- S Testaz
- Laboratoire de Biologie Mol¿eculaire et Cellulaire du D¿eveloppement, UMR 7622, CNRS et Universit¿e Pierre et Marie Curie, 75005 Paris, France
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129
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Yang JT, Bader BL, Kreidberg JA, Ullman-Culleré M, Trevithick JE, Hynes RO. Overlapping and independent functions of fibronectin receptor integrins in early mesodermal development. Dev Biol 1999; 215:264-77. [PMID: 10545236 DOI: 10.1006/dbio.1999.9451] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mouse embryos deficient in fibronectin (FN-null) die at E8.5 with mesodermal defects. Eight integrin heterodimers alpha3beta1, alpha4beta1, alpha5beta1, alpha8beta1, alphavbeta1, alphavbeta3, alphavbeta6, and alphaIIbbeta3 can bind to FN. However, embryos deficient in each of these integrins exhibit less severe defects than do FN-null embryos, raising questions as to which integrin(s) are the key FN receptors for these early FN-dependent processes. alpha5beta1 is believed to be the key receptor and alpha5-null embryos display mesodermal defects similar to, although less severe than, those of FN-null. Here we report that the alpha5-null mutation exhibits a more severe phenotype on a 129Sv (129) than on a C57BL/6 (B6) background, as does the FN-null mutation. While alpha5-null/B6 embryos develop normal headfolds, alpha5-null/129 embryos have headfold defects similar to those of FN-null. The differences between FN-null and alpha5-null embryos, however, cannot be attributed to genetic background. FN-null embryos never form somites, whereas in alpha5-null/129 embryos the somites do condense but fail to epithelialize. Second, we examined double mutants carrying all possible pairwise combinations of null mutations in alpha3, alpha4, and alpha5 integrin genes. There was no evidence for any synergy between paired mutations, suggesting that these integrin genes do not have overlapping functions during early embryonic development. Finally, we examined double-mutant embryos deficient in both alpha5 and alphav integrin genes. These double-mutant embryos have an amniotic defect similar to that of FN-null embryos, but die even earlier with a defect in gastrulation. These studies thus revealed a gradation in the severity of defects in the mutations alpha5(-/-); alphav(-/-) > FN(-/-) (129) > FN(-/-) (B6) > alpha5(-/-) (129) > alpha5(-/-) (B6), and in each step in this series there is a certain degree of phenotypic overlap, suggesting that the defects arising from these mutations may result from disruptions of the same embryonic process.
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Affiliation(s)
- J T Yang
- Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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130
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Kapila YL, Wang S, Johnson PW. Mutations in the heparin binding domain of fibronectin in cooperation with the V region induce decreases in pp125(FAK) levels plus proteoglycan-mediated apoptosis via caspases. J Biol Chem 1999; 274:30906-13. [PMID: 10521484 DOI: 10.1074/jbc.274.43.30906] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Intact fibronectin (FN) protects cells from apoptosis. When FN is fragmented, specific domains induce proteinase expression in fibroblasts. However, it is not known whether specific domains of FN can also regulate apoptosis. We exposed fibroblasts to four recombinant FN fragments and then assayed for apoptosis using criteria of cellular shape change, condensed nuclear morphology, and DNA fragmentation. The fragments extended from the RGD-containing repeat III10 to III15; they included (V(+)) or excluded (V(-)) the alternatively spliced V region and contained either a mutated (H(-)) or an unmutated (H(+)) heparin binding domain. Only the V(+)H(-) fragment triggered decreases in pp125(FAK) levels and apoptosis, which was rescued by intact FN and inhibitors of caspase-1 and caspase-3. This apoptotic mechanism was mediated by a chondroitin sulfate proteoglycan, since treating cells with chondroitin sulfate or chondroitinase reversed the apoptotic cell shape changes. The alpha4 integrin receptor may also be involved, since using a blocking antibody to alpha4 alone induced apoptotic cell shape changes, whereas co-treatment with this antibody plus V(+)H(+) reversed these effects. These results demonstrate that the V and heparin binding domains of FN modulate pp125(FAK) levels and regulate apoptosis through a chondroitin sulfate proteoglycan- and possibly alpha4 integrin-mediated pathway, which triggers a caspase cascade.
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Affiliation(s)
- Y L Kapila
- Department of Stomatology, University of California, San Francisco, California 94143-0512, USA.
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131
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De Arcangelis A, Mark M, Kreidberg J, Sorokin L, Georges-Labouesse E. Synergistic activities of alpha3 and alpha6 integrins are required during apical ectodermal ridge formation and organogenesis in the mouse. Development 1999; 126:3957-68. [PMID: 10433923 DOI: 10.1242/dev.126.17.3957] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Integrins alpha6beta1 and alpha6beta4 are cell surface receptors for laminins. Integrin alpha6-null mice die at birth with severe skin blistering and defects in the cerebral cortex and in the retina. Integrin alpha3beta1 can associate with laminins and other ligands. Integrin alpha3-null mice also die at birth, with kidney and lung defects at late stages of development, and moderate skin blistering. To investigate possible overlapping functions between alpha3 and alpha6 integrins, we analyzed the phenotype of compound alpha3−/−/alpha6−/− mutant embryos. Double homozygous mutant embryos were growth-retarded and displayed several developmental defects not observed in the single mutant animals. First, limb abnormalities characterized by an absence of digit separation and the fusion of preskeletal elements were observed. Further analyses indicated a defect in the apical ectodermal ridge, an essential limb organizing center. In the double mutant, the ridge appeared flattened, and ridge cells did not show a columnar morphology. A strong reduction in ridge cell proliferation and alterations of the basal lamina underlying the ectoderm were observed. These results suggest that alpha3 and alpha6 integrins are required for the organization or compaction of presumptive apical ectodermal ridge cells into a distinct differentiated structure. Additional defects were present: an absence of neural tube closure, bilateral lung hypoplasia, and several abnormalities in the urogenital tract. Finally, an aggravation of brain and eye lamination defects was observed. The presence of novel phenotypes in double mutant embryos demonstrates the synergism between alpha3 and alpha6 integrins and their essential roles in multiple processes during embryogenesis.
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Affiliation(s)
- A De Arcangelis
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP 163, CU de Strasbourg, France
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132
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Abstract
Many growth factors and their protein kinase receptors play a role in regulating vascular development. In addition, cell adhesion molecules, such as integrins and their ligands in the extracellular matrix, play important roles in the adhesion, migration, proliferation, survival and differentiation of the cells that form the vasculature. Some integrins are known to be regulated by angiogenic growth factors and studies with inhibitors of integrin functions and using strains of mice lacking specific integrins clearly implicate some of these molecules in vasculogenesis and angiogenesis. However, the data are incomplete and sometimes discordant and it is unclear how angiogenic growth factors and integrin-mediated adhesive events cooperate in the diverse cell biological processes involved in forming the vasculature. Consideration of the results suggests working hypotheses and raises questions for future research directions.
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Affiliation(s)
- R O Hynes
- Howard Hughes Medical Institute, Cambridge, MA, USA.
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133
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Bader BL, Rayburn H, Crowley D, Hynes RO. Extensive vasculogenesis, angiogenesis, and organogenesis precede lethality in mice lacking all alpha v integrins. Cell 1998; 95:507-19. [PMID: 9827803 DOI: 10.1016/s0092-8674(00)81618-9] [Citation(s) in RCA: 477] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
alphav integrins have been implicated in many developmental processes and are therapeutic targets for inhibition of angiogenesis and osteoporosis. Surprisingly, ablation of the gene for the alphav integrin subunit, eliminating all five alphav integrins, although causing lethality, allows considerable development and organogenesis including, most notably, extensive vasculogenesis and angiogenesis. Eighty percent of embryos die in mid-gestation, probably because of placental defects, but all embryos develop normally to E9.5, and 20% are born alive. These liveborn alphav-null mice consistently exhibit intracerebral and intestinal hemorrhages and cleft palates. These results necessitate reevaluation of the primacy of alphav integrins in many functions including vascular development, despite reports that blockade of these integrins with antibodies or peptides prevents angiogenesis.
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Affiliation(s)
- B L Bader
- Howard Hughes Medical Institute, Center for Cancer Research, Cambridge, Massachusetts 02139, USA
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134
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Taverna D, Disatnik MH, Rayburn H, Bronson RT, Yang J, Rando TA, Hynes RO. Dystrophic muscle in mice chimeric for expression of alpha5 integrin. J Biophys Biochem Cytol 1998; 143:849-59. [PMID: 9813102 PMCID: PMC2148145 DOI: 10.1083/jcb.143.3.849] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
alpha5-deficient mice die early in embryogenesis (). To study the functions of alpha5 integrin later in mouse embryogenesis and during adult life we generated alpha5 -/-;+/+ chimeric mice. These animals contain alpha5-negative and positive cells randomly distributed. Analysis of the chimerism by glucose- 6-phosphate isomerase (GPI) assay revealed that alpha5 -/- cells contributed to all the tissues analyzed. High contributions were observed in the skeletal muscle. The perinatal survival of the mutant chimeras was lower than for the controls, however the subsequent life span of the survivors was only slightly reduced compared with controls (). Histological analysis of alpha5 -/-;+/+ mice from late embryogenesis to adult life revealed an alteration in the skeletal muscle structure resembling a typical muscle dystrophy. Giant fibers, increased numbers of nuclei per fiber with altered position and size, vacuoli and signs of muscle degeneration-regeneration were observed in head, thorax and limb muscles. Electron microscopy showed an increase in the number of mitochondria in some muscle fibers of the mutant mice. Increased apoptosis and immunoreactivity for tenascin-C were observed in mutant muscle fibers. All the alterations were already visible at late stages of embryogenesis. The number of altered muscle fibers varied in different animals and muscles and was often increased in high percentage chimeric animals. Differentiation of alpha5 -/- ES cells or myoblasts showed that in vitro differentiation into myotubes was achieved normally. However proper adhesion and survival of myoblasts on fibronectin was impaired. Our data suggest that a novel form of muscle dystrophy in mice is alpha5-integrin-dependent.
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Affiliation(s)
- D Taverna
- Howard Hughes Medical Institute and Center for Cancer Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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135
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Helbling PM, Tran CT, Brändli AW. Requirement for EphA receptor signaling in the segregation of Xenopus third and fourth arch neural crest cells. Mech Dev 1998; 78:63-79. [PMID: 9858686 DOI: 10.1016/s0925-4773(98)00148-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We describe here the isolation of a full-length cDNA encoding a Xenopus orthologue of the mammalian EphA2 receptor tyrosine kinase and investigate its role in cranial neural crest migration. We show that the primary sites of Xenopus EphA2 expression are rhombomere 4 of the developing hindbrain, migratory cranial neural crest cells and mesoderm of the visceral arches. To interfere with EphA2 and related receptors during cranial neural crest migration, we took a dominant negative approach. Overexpression of kinase-deficient EphA2 receptor variants led to abnormal migration of cranial neural crest cells. Neural crest cells of the third arch were found to mismigrate posteriorly, resulting in the failure of third and fourth arch neural crest to separate into distinct streams. These defects could be rescued by expression of full-length EphA2 receptors. A comparison of the expression domains of EphA2-binding proteins mapped by receptor affinity probe (RAP) in situ staining with those for EphA2 receptors revealed co-expression of ligands and receptors in the visceral arch mesenchyme. Taken together, these results suggest that EphA receptors may mediate attractive or adhesive signals during migration of cranial neural crest cells.
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Affiliation(s)
- P M Helbling
- Institute of Cell Biology, Swiss Federal Institute of Technology, ETH-Hönggerberg, CH-8093, Zürich, Switzerland
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136
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Boudreau N, Bissell MJ. Extracellular matrix signaling: integration of form and function in normal and malignant cells. Curr Opin Cell Biol 1998; 10:640-6. [PMID: 9818175 PMCID: PMC2933204 DOI: 10.1016/s0955-0674(98)80040-9] [Citation(s) in RCA: 237] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A growing number of studies have established reciprocal linkages between extracellular matrix (ECM)-integrins, growth factor signaling and cell-cell adhesion molecules. ECM-dependent tissue-specific gene expression has also been linked to chromatin remodeling. With respect to tissue morphogenesis and differentiation, crosstalk has been established between the ECM and the homeobox morphoregulatory genes. Each of these linkages is profoundly influenced by the cell's microenvironment and the resulting tissue form. Thus for a cell to achieve a differentiated phenotype, the ECM molecules and their receptors must integrate both form and function. In contrast, mutated genes and aberrant interactions with the microenvironment conspire to undermine this integration, often resulting in malignant transformation.
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Affiliation(s)
- Nancy Boudreau
- Surgical Research Laboratory, University of California, San Francisco, CA 94143, USA
| | - Mina J Bissell
- Lawrence Berkeley National Laboratory, Life Sciences Division, One Cyclotron Road, MS 83-101, Berkeley, CA 94720, USA;
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137
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Griffin KJ, Amacher SL, Kimmel CB, Kimelman D. Molecular identification of spadetail: regulation of zebrafish trunk and tail mesoderm formation by T-box genes. Development 1998; 125:3379-88. [PMID: 9693141 DOI: 10.1242/dev.125.17.3379] [Citation(s) in RCA: 227] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Inhibition of fibroblast growth factor (FGF) signaling prevents trunk and tail formation in Xenopus and zebrafish embryos. While the T-box transcription factor Brachyury (called No Tail in zebrafish) is a key mediator of FGF signaling in the notochord and tail, the pathways activated by FGF in non-notochordal trunk mesoderm have been uncertain. Previous studies have shown that the spadetail gene is required for non-notochordal trunk mesoderm formation; spadetail mutant embryos have major trunk mesoderm deficiencies, but relatively normal tail and notochord development. We demonstrate here that spadetail encodes a T-box transcription factor with homologues in Xenopus and chick. Spadetail is likely to be a key mediator of FGF signaling in trunk non-notochordal mesoderm, since spadetail expression is regulated by FGF signaling. Trunk and tail development are therefore dependent upon the complementary actions of two T-box genes, spadetail and no tail. We show that the regulatory hierarchy among spadetail, no tail and a third T-box gene, tbx6, are substantially different during trunk and tail mesoderm formation, and propose a genetic model that accounts for the regional phenotypes of spadetail and no tail mutants.
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Affiliation(s)
- K J Griffin
- Department of Biochemistry, Box 357350, University of Washington, Seattle, Washington 98195-7350, USA
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138
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Pozzi A, Wary KK, Giancotti FG, Gardner HA. Integrin alpha1beta1 mediates a unique collagen-dependent proliferation pathway in vivo. J Cell Biol 1998; 142:587-94. [PMID: 9679154 PMCID: PMC2133043 DOI: 10.1083/jcb.142.2.587] [Citation(s) in RCA: 237] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/1998] [Revised: 06/09/1998] [Indexed: 02/08/2023] Open
Abstract
Activation of integrins upon binding to extracellular matrix proteins is believed to be a crucial step for the regulation of cell survival and proliferation. We have used integrin alpha1-null mice to investigate the role of this collagen receptor in the regulation of cell growth and survival in vivo. alpha1-deficient animals, which are viable and fertile, have a hypocellular dermis and a deficiency in dermal fibroblast proliferation as embryos. In vitro analysis of alpha1-null embryonic fibroblasts has revealed that their proliferation rate is markedly reduced when plated on collagenous substrata, despite normal attachment and spreading. Moreover, on the same collagenous matrices, alpha1-null fibroblasts fail to recruit and activate the adaptor protein Shc. The failure to activate Shc is accompanied by a downstream deficiency in recruitment of Grb2 and subsequent mitogen-activated protein kinase activation. Taken together with the growth deficiency observed on collagens, this finding indicates that the alpha1beta1 is the sole collagen receptor which can activate the Shc mediated growth pathway. Thus, integrin alpha1 has a unique role among the collagen receptors in regulating both in vivo and in vitro cell proliferation in collagenous matrices.
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Affiliation(s)
- A Pozzi
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA
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