101
|
Treanor B, Depoil D, Gonzalez-Granja A, Barral P, Weber M, Dushek O, Bruckbauer A, Batista FD. The membrane skeleton controls diffusion dynamics and signaling through the B cell receptor. Immunity 2010; 32:187-99. [PMID: 20171124 PMCID: PMC2984614 DOI: 10.1016/j.immuni.2009.12.005] [Citation(s) in RCA: 243] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Revised: 11/17/2009] [Accepted: 12/04/2009] [Indexed: 11/29/2022]
Abstract
Early events of B cell activation after B cell receptor (BCR) triggering have been well characterized. However, little is known about the steady state of the BCR on the cell surface. Here, we simultaneously visualize single BCR particles and components of the membrane skeleton. We show that an ezrin- and actin-defined network influenced steady-state BCR diffusion by creating boundaries that restrict BCR diffusion. We identified the intracellular domain of Igβ as important in mediating this restriction in diffusion. Importantly, alteration of this network was sufficient to induce robust intracellular signaling and concomitant increase in BCR mobility. Moreover, by using B cells deficient in key signaling molecules, we show that this signaling was most probably initiated by the BCR. Thus, our results suggest the membrane skeleton plays a crucial function in controlling BCR dynamics and thereby signaling, in a way that could be important for understanding tonic signaling necessary for B cell development and survival.
Collapse
Affiliation(s)
- Bebhinn Treanor
- Lymphocyte Interaction Laboratory, London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | | | | | | | | | | | | | | |
Collapse
|
102
|
VAV2 and VAV3 as candidate disease genes for spontaneous glaucoma in mice and humans. PLoS One 2010; 5:e9050. [PMID: 20140222 PMCID: PMC2816215 DOI: 10.1371/journal.pone.0009050] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Accepted: 01/18/2010] [Indexed: 12/22/2022] Open
Abstract
Background Glaucoma is a leading cause of blindness worldwide. Nonetheless, the mechanism of its pathogenesis has not been well-elucidated, particularly at the molecular level, because of insufficient availability of experimental genetic animal models. Methodology/Principal Findings Here we demonstrate that deficiency of Vav2 and Vav3, guanine nucleotides exchange factors for Rho guanosine triphosphatases, leads to an ocular phenotype similar to human glaucoma. Vav2/Vav3-deficient mice, and to a lesser degree Vav2-deficient mice, show early onset of iridocorneal angle changes and elevated intraocular pressure, with subsequent selective loss of retinal ganglion cells and optic nerve head cupping, which are the hallmarks of glaucoma. The expression of Vav2 and Vav3 tissues was demonstrated in the iridocorneal angle and retina in both mouse and human eyes. In addition, a genome-wide association study screening glaucoma susceptibility loci using single nucleotide polymorphisms analysis identified VAV2 and VAV3 as candidates for associated genes in Japanese open-angle glaucoma patients. Conclusions/Significance Vav2/Vav3-deficient mice should serve not only as a useful murine model of spontaneous glaucoma, but may also provide a valuable tool in understanding of the pathogenesis of glaucoma in humans, particularly the determinants of altered aqueous outflow and subsequent elevated intraocular pressure.
Collapse
|
103
|
Quevedo C, Sauzeau V, Menacho-Márquez M, Castro-Castro A, Bustelo XR. Vav3-deficient mice exhibit a transient delay in cerebellar development. Mol Biol Cell 2010; 21:1125-39. [PMID: 20089829 PMCID: PMC2836963 DOI: 10.1091/mbc.e09-04-0292] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Vav3 is a guanosine diphosphate/guanosine triphosphate exchange factor for Rho/Rac GTPases that has been involved in functions related to the hematopoietic system, bone formation, cardiovascular regulation, angiogenesis, and axon guidance. We report here that Vav3 is expressed at high levels in Purkinje and granule cells, suggesting additional roles for this protein in the cerebellum. Consistent with this hypothesis, we demonstrate using Vav3-deficient mice that this protein contributes to Purkinje cell dendritogenesis, the survival of granule cells of the internal granular layer, the timely migration of granule cells of the external granular layer, and to the formation of the cerebellar intercrural fissure. With the exception of the latter defect, the dysfunctions found in Vav3(-/-) mice only occur at well-defined postnatal developmental stages and disappear, or become ameliorated, in older animals. Vav2-deficient mice do not show any of those defects. Using primary neuronal cultures, we show that Vav3 is important for dendrite branching, but not for primary dendritogenesis, in Purkinje and granule cells. Vav3 function in the cerebellum is functionally relevant, because Vav3(-/-) mice show marked motor coordination and gaiting deficiencies in the postnatal period. These results indicate that Vav3 function contributes to the timely developmental progression of the cerebellum.
Collapse
Affiliation(s)
- Celia Quevedo
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas, University of Salamanca, Campus Unamuno, E-37007 Salamanca, Spain
| | | | | | | | | |
Collapse
|
104
|
Saveliev A, Vanes L, Ksionda O, Rapley J, Smerdon SJ, Rittinger K, Tybulewicz VLJ. Function of the nucleotide exchange activity of vav1 in T cell development and activation. Sci Signal 2009; 2:ra83. [PMID: 20009105 PMCID: PMC3434450 DOI: 10.1126/scisignal.2000420] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The guanine nucleotide exchange factor (GEF) Vav1 is essential for transducing T cell antigen receptor (TCR) signals and therefore plays a critical role in the development and activation of T cells. It has been presumed that the GEF activity of Vav1 is important for its function; however, there has been no direct demonstration of this. Here, we generated mice expressing enzymatically inactive, but normally folded, Vav1 protein. Analysis of these mice showed that the GEF activity of Vav1 was necessary for the selection of thymocytes and for the optimal activation of T cells, including signal transduction to Rac1, Akt, and integrins. In contrast, the GEF activity of Vav1 was not required for TCR-induced calcium flux, activation of extracellular signal-regulated kinase and protein kinase D1, and cell polarization. Thus, in T cells, the GEF activity of Vav1 is essential for some, but not all, of its functions.
Collapse
Affiliation(s)
- Alexander Saveliev
- Division of Immune Cell Biology, MRC National Institute for Medical Research, London, UK
| | - Lesley Vanes
- Division of Immune Cell Biology, MRC National Institute for Medical Research, London, UK
| | - Olga Ksionda
- Division of Immune Cell Biology, MRC National Institute for Medical Research, London, UK
| | - Jonathan Rapley
- Division of Immune Cell Biology, MRC National Institute for Medical Research, London, UK
- Division of Molecular Structure, MRC National Institute for Medical Research, London, UK
| | - Stephen J. Smerdon
- Division of Molecular Structure, MRC National Institute for Medical Research, London, UK
| | - Katrin Rittinger
- Division of Molecular Structure, MRC National Institute for Medical Research, London, UK
| | | |
Collapse
|
105
|
Chang JW, Koike T, Iwashima M. hnRNP-K is a nuclear target of TCR-activated ERK and required for T-cell late activation. Int Immunol 2009; 21:1351-61. [PMID: 19880579 DOI: 10.1093/intimm/dxp106] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Sustained extracellular signal-regulated kinase (ERK)-signaling plays a critical role in T-cell-mediated IL-2 production. Although many downstream targets are known for ERK, details remain unknown about which molecules play functional roles in IL-2 production. Here, we addressed this question using proteomic analysis of nuclear proteins from TCR-activated T cells and identified hnRNP-K as one of the ERK targets essential for IL-2 production. hnRNP-K was previously shown by others to be a direct substrate of ERK and form complexes with multiple signaling proteins as well as DNA and RNA. Our data showed a clear ERK-dependent increase in one form of hnRNP-K after TCR stimulation. Small interfering RNA-mediated gene knockdown of hnRNP-K expression abrogated IL-2 production by T cells. Moreover, reduction of hnRNP-K expression caused a notable increase in proteolysis of Vav1, a binding target of hnRNP-K. Since Vav1 is an essential molecule for T-cell activation, the data suggest that ERK signaling is required for T-cell activation partly by inhibiting activation-induced proteolysis of Vav1.
Collapse
Affiliation(s)
- Jing-Wen Chang
- Department of Medicine, Immunotherapy Center, Medical College of Georgia, Augusta, GA 30912-2600, USA
| | | | | |
Collapse
|
106
|
Bhavsar PJ, Vigorito E, Turner M, Ridley AJ. Vav GEFs regulate macrophage morphology and adhesion-induced Rac and Rho activation. Exp Cell Res 2009; 315:3345-58. [PMID: 19715691 DOI: 10.1016/j.yexcr.2009.08.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 08/18/2009] [Accepted: 08/21/2009] [Indexed: 12/18/2022]
Abstract
The Vav family of proteins have the potential to act as both signalling adapters and GEFs for Rho GTPases. They have therefore been proposed as regulators of the cytoskeleton in various cell types. We have used macrophages from mice deficient in all three Vav isoforms to determine how their function affects cell morphology and migration. Macrophages lacking Vav proteins adopt an elongated morphology and have enhanced migratory persistence in culture. To investigate the pathways through which Vav proteins exert their effects we analysed the responses of macrophages to the chemoattractant CSF-1 and to adhesion. We found that morphological and signalling responses of macrophages to CSF-1 did not require Vav proteins. In contrast, adhesion-induced cell spreading, RhoA and Rac1 activation and cell signalling were all dependent on Vav proteins. We propose that Vav proteins affect macrophage morphology and motile behaviour by coupling adhesion receptors to Rac1 and RhoA activity and regulating adhesion signalling events such as paxillin and ERK1/2 phosphorylation by acting as adapters.
Collapse
Affiliation(s)
- Parag J Bhavsar
- King's College London, Randall Division of Cell and Molecular Biophysics, Guy's Campus, London, UK
| | | | | | | |
Collapse
|
107
|
Abstract
Rho family GTPases, and the proteins that regulate them, have important roles in many cellular processes, including cell division, survival, migration and adhesion. Although most of our understanding of these proteins has come from studies using cell lines, more recent gene targeting studies in mice are providing insights into the in vivo function of these proteins. Here we review recent progress revealing crucial roles for these proteins in lymphocyte development, activation, differentiation and migration. The emerging picture shows that Rho family GTPases transduce signals from receptors for antigens, chemokines and cytokines, as well as adhesion molecules and pattern recognition receptors, and that they function as focal points for crosstalk between different signalling pathways.
Collapse
|
108
|
Miletic AV, Graham DB, Sakata-Sogawa K, Hiroshima M, Hamann MJ, Cemerski S, Kloeppel T, Billadeau DD, Kanagawa O, Tokunaga M, Swat W. Vav links the T cell antigen receptor to the actin cytoskeleton and T cell activation independently of intrinsic Guanine nucleotide exchange activity. PLoS One 2009; 4:e6599. [PMID: 19672294 PMCID: PMC2719804 DOI: 10.1371/journal.pone.0006599] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Accepted: 07/09/2009] [Indexed: 12/19/2022] Open
Abstract
Background T cell receptor (TCR) engagement leads to formation of signaling microclusters and induction of rapid and dynamic changes in the actin cytoskeleton, although the exact mechanism by which the TCR initiates actin polymerization is incompletely understood. The Vav family of guanine nucleotide exchange factors (GEF) has been implicated in generation of TCR signals and immune synapse formation, however, it is currently not known if Vav's GEF activity is required in T cell activation by the TCR in general, and in actin polymerization downstream of the TCR in particular. Methodology/Principal Findings Here, we report that Vav1 assembles into signaling microclusters at TCR contact sites and is critical for TCR-initiated actin polymerization. Surprisingly, Vav1 functions in TCR signaling and Ca++ mobilization via a mechanism that does not appear to strictly depend on the intrinsic GEF activity. Conclusions/Significance We propose here a model in which Vav functions primarily as a tyrosine phosphorylated linker-protein for TCR activation of T cells. Our results indicate that, contrary to expectations based on previously published studies including from our own laboratory, pharmacological inhibition of Vav1's intrinsic GEF activity may not be an effective strategy for T cell-directed immunosuppressive therapy.
Collapse
Affiliation(s)
- Ana V. Miletic
- Department of Pathology and Immunology, Washington University School of Medicine and Siteman Cancer Center, St. Louis, Missouri, United States of America
| | - Daniel B. Graham
- Department of Pathology and Immunology, Washington University School of Medicine and Siteman Cancer Center, St. Louis, Missouri, United States of America
| | - Kumiko Sakata-Sogawa
- Research Unit for Single Molecule Immunoimaging, RIKEN Center for Allergy and Immunology, Yokohama, Kanagawa, Japan
| | - Michio Hiroshima
- Research Unit for Single Molecule Immunoimaging, RIKEN Center for Allergy and Immunology, Yokohama, Kanagawa, Japan
| | - Michael J. Hamann
- Department of Immunology and Division of Oncology Research, Mayo Clinic College of Medicine, Rochester, Minnesota, United States of America
| | - Saso Cemerski
- Department of Pathology and Immunology, Washington University School of Medicine and Siteman Cancer Center, St. Louis, Missouri, United States of America
| | - Tracie Kloeppel
- Department of Pathology and Immunology, Washington University School of Medicine and Siteman Cancer Center, St. Louis, Missouri, United States of America
| | - Daniel D. Billadeau
- Department of Immunology and Division of Oncology Research, Mayo Clinic College of Medicine, Rochester, Minnesota, United States of America
| | - Osami Kanagawa
- Laboratory for Autoimmune Regulation, RIKEN Center for Allergy and Immunology, Yokohama, Kanagawa, Japan
| | - Makio Tokunaga
- Research Unit for Single Molecule Immunoimaging, RIKEN Center for Allergy and Immunology, Yokohama, Kanagawa, Japan
- Structural Biology Center, National Institute of Genetics, The Graduate University for Advanced Studies, Mishima, Shizuoka, Japan
- Department of Genetics, The Graduate University for Advanced Studies, Mishima, Shizuoka, Japan
| | - Wojciech Swat
- Department of Pathology and Immunology, Washington University School of Medicine and Siteman Cancer Center, St. Louis, Missouri, United States of America
- * E-mail:
| |
Collapse
|
109
|
Malhotra S, Kovats S, Zhang W, Coggeshall KM. B cell antigen receptor endocytosis and antigen presentation to T cells require Vav and dynamin. J Biol Chem 2009; 284:24088-97. [PMID: 19586920 DOI: 10.1074/jbc.m109.014209] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Antigen binding to the B cell antigen receptor (BCR) initiates an array of signaling events. These include endocytosis of ligand-receptor complexes via clathrin-coated pits, trafficking of the internalized ligand to lysosomes, degradation of the associated proteins to peptides, and peptide presentation on nascent major histocompatibility complex class II to T cells. The signal transduction events supporting BCR internalization are not well understood. We have identified a pathway supporting BCR internalization that includes the Vav1 and/or Vav3 isoforms and the GTPase dynamin. Vav1 and -3 are not required for B cell development and maturation, nor for a variety of BCR-induced signaling events nor for BCR signaling leading to major histocompatibility complex class II and CD80 expression, but Vav1 and/or -3 are absolutely required for BCR endocytosis and BCR-induced Rac-GTP loading. This is the first demonstration of a link between Vav and Rac in BCR internalization leading to antigen presentation to T cells.
Collapse
Affiliation(s)
- Shikha Malhotra
- Immunobiology and Cancer Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA
| | | | | | | |
Collapse
|
110
|
Brantley-Sieders DM, Zhuang G, Vaught D, Freeman T, Hwang Y, Hicks D, Chen J. Host deficiency in Vav2/3 guanine nucleotide exchange factors impairs tumor growth, survival, and angiogenesis in vivo. Mol Cancer Res 2009; 7:615-23. [PMID: 19435813 PMCID: PMC2739740 DOI: 10.1158/1541-7786.mcr-08-0401] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Vav guanine nucleotide exchange factors modulate changes in cytoskeletal organization through activation of Rho, Rac, and Cdc42 small GTPases. Although Vav1 expression is restricted to the immune system, Vav2 and Vav3 are expressed in several tissues, including highly vascularized organs. Here, we provide the first evidence that Vav2 and Vav3 function within the tumor microenvironment to promote tumor growth, survival, and neovascularization. Host Vav2/3 deficiency reduced microvascular density, as well as tumor growth and/or survival, in transplanted B16 melanoma and Lewis lung carcinoma models in vivo. These defects were due in part to Vav2/3 deficiency in endothelial cells. Vav2/3-deficient endothelial cells displayed reduced migration in response to tumor cells in coculture migration assays, and failed to incorporate into tumor vessels and enhance tumor volume in tumor-endothelial cotransplantation experiments. These data suggest that Vav2/3 guanine nucleotide exchange factors play a critical role in host-mediated tumor progression and angiogenesis, particularly in tumor endothelium.
Collapse
MESH Headings
- Animals
- Carcinoma, Lewis Lung/blood supply
- Carcinoma, Lewis Lung/pathology
- Carcinoma, Lewis Lung/physiopathology
- Cell Line, Tumor
- Cell Movement
- Cell Proliferation
- Cell Survival
- Coculture Techniques
- Endothelial Cells/cytology
- Endothelial Cells/physiology
- Melanoma, Experimental/blood supply
- Melanoma, Experimental/pathology
- Melanoma, Experimental/physiopathology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Nude
- Neoplasms, Experimental/blood supply
- Neoplasms, Experimental/pathology
- Neoplasms, Experimental/physiopathology
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/pathology
- Proto-Oncogene Proteins c-vav/deficiency
- Proto-Oncogene Proteins c-vav/genetics
- Proto-Oncogene Proteins c-vav/physiology
- Transplantation, Homologous
- Tumor Burden
- von Willebrand Factor/metabolism
Collapse
Affiliation(s)
- Dana M. Brantley-Sieders
- Department of Medicine, Division of Rheumatology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
| | - Guanglei Zhuang
- Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
| | - David Vaught
- Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
| | - Tanner Freeman
- Medical Scientist Training Program, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
| | - Yoonha Hwang
- Department of Medicine, Division of Rheumatology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
| | - Donna Hicks
- Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
| | - Jin Chen
- Department of Medicine, Division of Rheumatology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
- Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
- Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
| |
Collapse
|
111
|
Dumont C, Corsoni-Tadrzak A, Ruf S, de Boer J, Williams A, Turner M, Kioussis D, Tybulewicz VLJ. Rac GTPases play critical roles in early T-cell development. Blood 2009; 113:3990-8. [PMID: 19088377 PMCID: PMC2673125 DOI: 10.1182/blood-2008-09-181180] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Accepted: 12/14/2008] [Indexed: 01/11/2023] Open
Abstract
The Rac1 and Rac2 GTPases play important roles in many processes including cytoskeletal reorganization, proliferation, and survival, and are required for B-cell development. Previous studies had shown that deficiency in Rac2 did not affect T-cell development, whereas the function of Rac1 in this process has not been investigated. We now show that simultaneous absence of both GTPases resulted in a very strong developmental block at the pre-TCR checkpoint and in defective positive selection. Unexpectedly, deficiency of Rac1 and Rac2 also resulted in the aberrant survival of thymocytes lacking expression of TCR beta, showing hallmarks of hyperactive Notch signaling. Furthermore, we found a similar novel phenotype in the absence of Vav1, Vav2, and Vav3, which function as guanine nucleotide exchange factors for Rac1 and Rac2. These results show that a pathway containing Vav and Rac proteins may negatively regulate Notch signaling during early thymic development.
Collapse
Affiliation(s)
- Celine Dumont
- Division of Immune Cell Biology, Medical Research Council (MRC) National Institute for Medical Research, London, UK
| | | | | | | | | | | | | | | |
Collapse
|
112
|
Graham DB, Zinselmeyer BH, Mascarenhas F, Delgado R, Miller MJ, Swat W. ITAM signaling by Vav family Rho guanine nucleotide exchange factors regulates interstitial transit rates of neutrophils in vivo. PLoS One 2009; 4:e4652. [PMID: 19247495 PMCID: PMC2645696 DOI: 10.1371/journal.pone.0004652] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Accepted: 01/27/2009] [Indexed: 01/05/2023] Open
Abstract
Background In response to infection, neutrophils are quickly recruited from the blood into inflamed tissues. The interstitial migration of neutrophils is crucial for the efficient capture and control of rapidly proliferating microbes before microbial growth can overwhelm the host's defenses. However, the molecular mechanisms that regulate interstitial migration are incompletely understood. Methodology/Principal Findings Here, we use two-photon microscopy (2PM) to study discrete steps of neutrophil responses during subcutaneous infection with bacteria. Our study demonstrates that signals emanating from ITAM-containing receptors mediated by Vav family Rho GEFs control the velocity, but not the directionality, of neutrophil migration towards sites of bacterial infection. Conclusions/Significance Here we show that during neutrophil migration towards sites of bacterial infection, signals emanating from ITAM-containing receptors specifically control interstitial neutrophil velocity.
Collapse
Affiliation(s)
- Daniel B. Graham
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Bernd H. Zinselmeyer
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Francesca Mascarenhas
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Ryan Delgado
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Mark J. Miller
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri, United States of America
- * E-mail: (MJM); (WS)
| | - Wojciech Swat
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri, United States of America
- * E-mail: (MJM); (WS)
| |
Collapse
|
113
|
Imamura Y, Oda A, Katahira T, Bundo K, Pike KA, Ratcliffe MJH, Kitamura D. BLNK binds active H-Ras to promote B cell receptor-mediated capping and ERK activation. J Biol Chem 2009; 284:9804-13. [PMID: 19218240 DOI: 10.1074/jbc.m809051200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Cross-linked B cell receptor (BCR) aggregates on the cell surface, then assembles into the "cap" where Ras is co-localized, and transduces various intracellular signals including Ras-ERK activation. BCR signals induce proliferation, differentiation, or apoptosis of B cells depending on their maturational stage. The adaptor protein BLNK binds various signaling proteins and Igalpha, a signaling subunit of the BCR complex, and plays an important role in the BCR signal transduction. BLNK was shown to be required for activation of ERK, but not of Ras, after BCR cross-linking, raising a question how BLNK facilitates ERK activation. Here we demonstrate that BLNK binds the active form of H-Ras, and their binding is facilitated by BCR cross-linking. We have identified a 10-amino acid Ras-binding domain within BLNK that is necessary for restoration of BCR-mediated ERK activation in BLNK-deficient B cells and for anti-apoptotic signaling. The Ras-binding domain fused with a CD8alpha-Igalpha chimeric receptor could induce prolonged ERK phosphorylation, transcriptional activation of Elk1, as well as the capping of the receptor in BLNK-deficient B cells. These results indicate that BLNK recruits active H-Ras to the BCR complex, which is essential for sustained surface expression of BCR in the form of the cap and for the signal leading to functional ERK activation.
Collapse
Affiliation(s)
- Yasuhiro Imamura
- Division of Molecular Biology, Research Institute for Biological Sciences, Tokyo University of Science, 2669 Yamazaki, Noda, Chiba 278-0022, Japan
| | | | | | | | | | | | | |
Collapse
|
114
|
Raberger J, Boucheron N, Sakaguchi S, Penninger JM, Ellmeier W. Impaired T-cell development in the absence of Vav1 and Itk. Eur J Immunol 2009; 38:3530-42. [PMID: 19009524 DOI: 10.1002/eji.200838388] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Vav1 and the Tec family kinase Itk act in similar T-cell activation pathways. Both molecules interact with members of the Cbl family of E3 ubiquitin ligases, and signaling defects in Vav1(-/-) T cells are rescued upon deletion of Cbl-b. In this study we investigate the relation between Itk and Cbl-b or Vav1 by generating Itk/Cbl-b and Itk/Vav1 double-deficient mice. Deletion of Cbl-b in Itk(-/-) CD4(+) T cells restored proliferation and partially IL-2 production, and also led to a variable rescue of IL-4 production. Thus, Itk and Vav1 act mechanistically similarly in peripheral T cells, since the defects in Itk(-/-) T cells, as in Vav1(-/-) T cells, are rescued if cells are released from the negative regulation mediated by Cbl-b. In addition, only few peripheral CD4(+) and CD8(+) T cells were present in Vav1(-/-)Itk(-/-) mice due to severely impaired thymocyte differentiation. Vav1(-/-)Itk(-/-) thymocyte numbers were strongly reduced compared with WT, Itk(-/-) or Vav1(-/-) mice, and double-positive thymocytes displayed increased cell death and impaired positive selection. Therefore, our data also reveal that the combined activity of Vav1 and Itk is required for proper T-cell development and the generation of the peripheral T-cell pool.
Collapse
Affiliation(s)
- Julia Raberger
- Division of Immunobiology, Institute of Immunology, Center for Physiology, Pathophysiology and Immunology, Medical University of Vienna, Vienna, Austria
| | | | | | | | | |
Collapse
|
115
|
Wound healing defect of Vav3-/- mice due to impaired {beta}2-integrin-dependent macrophage phagocytosis of apoptotic neutrophils. Blood 2009; 113:5266-76. [PMID: 19147786 DOI: 10.1182/blood-2008-07-166702] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Vav proteins are guanine-nucleotide exchange factors implicated in leukocyte functions by relaying signals from immune response receptors and integrins to Rho-GTPases. We here provide first evidence for a role of Vav3 for beta(2)-integrins-mediated macrophage functions during wound healing. Vav3(-/-) and Vav1(-/-)/Vav3(-/-) mice revealed significantly delayed healing of full-thickness excisional wounds. Furthermore, Vav3(-/-) bone marrow chimeras showed an identical healing defect, suggesting that Vav3 deficiency in leukocytes, but not in other cells, is causal for the impaired wound healing. Vav3 was required for the phagocytotic cup formation preceding macrophage phagocytosis of apoptotic neutrophils. Immunoprecipitation and confocal microscopy revealed Vav3 activation and colocalization with beta(2)-integrins at the macrophage membrane upon adhesion to ICAM-1. Moreover, local injection of Vav3(-/-) or beta(2)-integrin(CD18)(-/-) macrophages into wound margins failed to restore the healing defect of Vav3(-/-) mice, suggesting Vav3 to control the beta(2)-integrin-dependent formation of a functional phagocytic synapse. Impaired phagocytosis of apoptotic neutrophils by Vav3(-/-) macrophages was causal for their reduced release of active transforming growth factor (TGF)-beta(1), for decreased myofibroblasts differentiation and myofibroblast-driven wound contraction. TGF-beta(1) deficiency in Vav3(-/-) macrophages was causally responsible for the healing defect, as local injection of either Vav3-competent macrophages or recombinant TGF-beta(1) into wounds of Vav3(-/-) mice fully rescued the delayed wound healing.
Collapse
|
116
|
Liu JY, Seno H, Miletic AV, Mills JC, Swat W, Stappenbeck TS. Vav proteins are necessary for correct differentiation of mouse cecal and colonic enterocytes. J Cell Sci 2009; 122:324-34. [PMID: 19139088 DOI: 10.1242/jcs.033720] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
In the mammalian cecum and colon, a single layer of absorptive, mature enterocytes are a crucial element of the physical barrier to the contents of the lumen. Enterocytic differentiation involves expansion of cytoplasmic cytoskeletal networks, which have been proposed to maintain structural integrity of individual cells and thus the entire epithelial barrier. We sought molecular tools to test this hypothesis in vivo, because in vitro systems displaying full intestinal epithelial differentiation have not yet been developed. Vav proteins are RhoGEFs that modulate cytoskeletal networks in immune cells. We found that Vav proteins were preferentially expressed in terminally differentiating cecal and colonic enterocytes. Loss of Vav protein expression in triple-knockout mice (Vav1(-/-);Vav2(-/-);Vav3(-/-)) resulted in defective expansion of microtubule cytoskeletons, a significant decrease in cell height and diminished expression of differentiation markers. Despite these changes, enterocytes in the triple-mutant mice did not contain measurable alterations in actin cytoskeleton, apical cell-cell junctions, nuclear position or global polarized delivery of proteins involved in terminal differentiation. Aged triple-mutant mice spontaneously developed ulcerative lesions that were, in part, a result of defective wound repair. These studies show that Vav proteins are required for enterocytic differentiation and colonic epithelial barrier integrity.
Collapse
Affiliation(s)
- John Y Liu
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110, USA
| | | | | | | | | | | |
Collapse
|
117
|
Targeted cleavage of signaling proteins by caspase 3 inhibits T cell receptor signaling in anergic T cells. Immunity 2008; 29:193-204. [PMID: 18701083 DOI: 10.1016/j.immuni.2008.06.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2007] [Revised: 03/26/2008] [Accepted: 06/10/2008] [Indexed: 11/22/2022]
Abstract
T cell receptor (TCR) engagement in the absence of costimulation induces the calcium-dependent upregulation of a program of gene expression that leads to the establishment of T cell anergy. Casp3 is one of the genes activated during anergy induction. Here we show that caspase 3 is required for the induction of T cell unresponsiveness. Suboptimal T cell stimulation induced caspase 3 activation, which did not result in cell death. Furthermore, caspase 3-deficient T cells showed impaired responses to anergizing stimuli. In anergic T cells, activated caspase 3 associated to the plasma membrane, where it cleaved and inactivated proteins such as the Grb2-related adaptor downstream of shc (GADS) and the guanine-nucleotide exchange factor Vav1, causing a blockade in TCR signaling. Our results identify a role for caspase 3 in nonapoptotic T cells and support that caspase 3-dependent proteolytic inactivation of signaling proteins is essential to maintain T cell tolerance.
Collapse
|
118
|
Park H, Staehling-Hampton K, Appleby MW, Brunkow ME, Habib T, Zhang Y, Ramsdell F, Liggitt HD, Freie B, Tsang M, Carlson G, Friend S, Frevert C, Iritani BM. A point mutation in the murine Hem1 gene reveals an essential role for Hematopoietic protein 1 in lymphopoiesis and innate immunity. ACTA ACUST UNITED AC 2008; 205:2899-913. [PMID: 19015308 PMCID: PMC2585840 DOI: 10.1084/jem.20080340] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Hem1 (Hematopoietic protein 1) is a hematopoietic cell-specific member of the Hem family of cytoplasmic adaptor proteins. Orthologues of Hem1 in Dictyostelium discoideum, Drosophila melanogaster, and Caenorhabditis elegans are essential for cytoskeletal reorganization, embryonic cell migration, and morphogenesis. However, the in vivo functions of mammalian Hem1 are not known. Using a chemical mutagenesis strategy in mice to identify novel genes involved in immune cell functions, we positionally cloned a nonsense mutation in the Hem1 gene. Hem1 deficiency results in defective F-actin polymerization and actin capping in lymphocytes and neutrophils caused by loss of the Rac-controlled actin-regulatory WAVE protein complex. T cell development is disrupted in Hem1-deficient mice at the CD4−CD8− (double negative) to CD4+CD8+ (double positive) cell stages, whereas T cell activation and adhesion are impaired. Hem1-deficient neutrophils fail to migrate in response to chemotactic agents and are deficient in their ability to phagocytose bacteria. Remarkably, some Rac-dependent functions, such as Th1 differentiation and nuclear factor κB (NF-κB)–dependent transcription of proinflammatory cytokines proceed normally in Hem1-deficient mice, whereas the production of Th17 cells are enhanced. These results demonstrate that Hem1 is essential for hematopoietic cell development, function, and homeostasis by controlling a distinct pathway leading to cytoskeletal reorganization, whereas NF-κB–dependent transcription proceeds independently of Hem1 and F-actin polymerization.
Collapse
Affiliation(s)
- Heon Park
- Department of Comparative Medicine, University of Washington, Seattle, WA 98195, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
119
|
Caloca MJ, Zugaza JL, Bustelo XR. Mechanistic analysis of the amplification and diversification events induced by Vav proteins in B-lymphocytes. J Biol Chem 2008; 283:36454-64. [PMID: 18974050 DOI: 10.1074/jbc.m803814200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Vav proteins participate in the assembly of a multibranched signal transduction pathway in lymphocytes, including the stimulation of the phosphatidylinositol 3-kinase/protein kinase B and the phospholipase C-gamma/Ras GDP-releasing protein/Ras/Erk routes. In the present work, we used a genetic approach in chicken DT40 B-cell lines to investigate additional elements of the Vav route, the synergisms existing among the different Vav signaling branches, and the activities exerted by wild-type and oncogenic Vav proteins in B-lymphocytes. We show here that the Vav pathway is ramified in B-lymphocytes in additional diacylglycerol-dependent signaling branches such as those involving protein kinase C, protein kinase D, and phospholipase D. By using side-by-side comparisons of the activation levels of those signal transduction pathways in inhibitor-treated and knockout DT40 cells, we show that B-cells have different requirements regarding Vav proteins for the activation of antigen receptor downstream elements. Furthermore, we have detected interpathway cross-talk at the level of the most proximal elements but not among the most distal effector molecules of the Vav route. Finally, we show that the oncogenic versions of Vav1 and RhoA can activate alternative routes that could contribute to signal amplification and diversification events in transformed lymphocytes.
Collapse
Affiliation(s)
- María J Caloca
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas, University of Salamanca, Campus Unamuno, Salamanca E-37007, Spain
| | | | | |
Collapse
|
120
|
Essential role of Rap signal in pre-TCR-mediated beta-selection checkpoint in alphabeta T-cell development. Blood 2008; 112:4565-73. [PMID: 18802005 DOI: 10.1182/blood-2008-06-164517] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We demonstrate that lck promoter-driven conditional expression of transgenic SPA-1, a Rap GTPase-activation protein, causes a profound defect of alphabeta T-cell development at the CD4/CD8 double-negative (DN) stage due to enhanced cell death without affecting gammadelta T-cell development. The effect was specific to the DN stage, because CD4 promoter-driven SPA-1 expression hardly affected T-cell development. Rap1A17, a dominant-negative Rap mutant, interfered with the generation of double-positive (DP) cells from Rag2(-/-) fetal thymocytes in vitro in the presence of anti-CD3epsilon antibody and Notch ligand. Rap GTPases were activated in a DN cell line by the expression of self-oligomerizing CD3 (CD8:CD3epsilon chimera), which substituted autonomous pre-T-cell receptor (TCR) signal, inducing CD69 expression and CD25 down-regulation. Reciprocally, expression of C3G, a Rap guanine nucleotide exchange factor, in both normal and Rag2(-/-) DN cells markedly enhanced Notch-dependent generation and expansion of DP cells without additional anti-CD3epsilon antibody, thus bypassing pre-TCR. Defective alphabeta T-cell development in the conditional SPA-1-transgenic mice was restored completely by introducing a p53(-/-) mutation. These results suggest that endogenous Rap GTPases downstream of pre-TCR play an essential role in rescuing pre-T cells from the p53-mediated checkpoint response, thus allowing Notch-mediated expansion and differentiation.
Collapse
|
121
|
Wang Z, Dong X, Li Z, Smith JD, Wu D. Lack of a significant role of P-Rex1, a major regulator of macrophage Rac1 activation and chemotaxis, in atherogenesis. Prostaglandins Other Lipid Mediat 2008; 87:9-13. [PMID: 18502673 DOI: 10.1016/j.prostaglandins.2008.04.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 03/31/2008] [Accepted: 04/14/2008] [Indexed: 12/24/2022]
Abstract
BACKGROUND Rho GTPases are known to play important roles in regulating multiple cellular processes that include cell polarization and migration. Among these Rho GTPases, Rac has been shown to be essential for F actin formation and cell migration. P-Rex1 is a guanine nucleotide exchange factor (GEF) that was previously found to mediate the activation of Rac2, but not Rac1, in mouse neutrophils. OBJECTIVES Here we examined the role of P-Rex1 in mouse macrophages and atherogenesis. METHODS AND RESULTS PBD (p21 binding domain) pull down assay was performed to compare the Rac1 activation in WT and P-Rex1-deficient macrophage. In addition, transwell assay was conducted to compare chemotaxis of WT and P-Rex1-deficient macrophage. We found that P-Rex1 is a major Rac1 regulator in mouse macrophages as its deficiency significantly compromises macrophage chemotaxis, superoxide production (SOD), and Rac1 activation in response to chemoattractants. The potential role of P-Rex1 in atherogenesis is also investigated by transferring P-Rex1-deficient bone marrow cells to LDLR deficient mice. Contrary to our prediction, P-Rex1 deficiency did not alter atherogenesis, suggesting chemoattractant-induced macrophage migration may not have a significant role in atherogenesis. CONCLUSIONS P-Rex1 is one of the major GEFs in macrophage regulating Rac1 activation and chemotaxis.
Collapse
Affiliation(s)
- Zhenglong Wang
- Program for Vascular Biology and Therapeutics and Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | | | | | | | | |
Collapse
|
122
|
Utomo A, Hirahashi J, Mekala D, Asano K, Glogauer M, Cullere X, Mayadas TN. Requirement for Vav Proteins in Post-Recruitment Neutrophil Cytotoxicity in IgG but Not Complement C3-Dependent Injury. THE JOURNAL OF IMMUNOLOGY 2008; 180:6279-87. [DOI: 10.4049/jimmunol.180.9.6279] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
123
|
Graham DB, Robertson CM, Bautista J, Mascarenhas F, Diacovo MJ, Montgrain V, Lam SK, Cremasco V, Dunne WM, Faccio R, Coopersmith CM, Swat W. Neutrophil-mediated oxidative burst and host defense are controlled by a Vav-PLCgamma2 signaling axis in mice. J Clin Invest 2008; 117:3445-52. [PMID: 17932569 DOI: 10.1172/jci32729] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Accepted: 07/18/2007] [Indexed: 01/08/2023] Open
Abstract
Oxidative burst, a critical antimicrobial mechanism of neutrophils, involves the rapid generation and release of reactive oxygen intermediates (ROIs) by the NADPH oxidase complex. Genetic mutations in an NADPH oxidase subunit, gp91 (also referred to as NOX2), are associated with chronic granulomatous disease (CGD), which is characterized by recurrent and life-threatening microbial infections. To combat such infections, ROIs are produced by neutrophils after stimulation by integrin-dependent adhesion to the ECM in conjunction with stimulation from inflammatory mediators, or microbial components containing pathogen-associated molecular patterns. In this report, we provide genetic evidence that both the Vav family of Rho GTPase guanine nucleotide exchange factors (GEFs) and phospholipase C-gamma2 (PLC-gamma2) are critical mediators of adhesion-dependent ROI production by neutrophils in mice. We also demonstrated that Vav was critically required for neutrophil-dependent host defense against systemic infection by Staphylococcus aureus and Pseudomonas aeruginosa, 2 common pathogens associated with fatal cases of hospital-acquired pneumonia. We identified a molecular pathway in which Vav GEFs linked integrin-mediated signaling with PLC-gamma2 activation, release of intracellular Ca2+ cations, and generation of diacylglycerol to control assembly of the NADPH oxidase complex and ROI production by neutrophils. Taken together, our data indicate that integrin-dependent signals generated during neutrophil adhesion contribute to the activation of NADPH oxidase by a variety of distinct effector pathways, all of which require Vav.
Collapse
Affiliation(s)
- Daniel B Graham
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
124
|
Torgersen KM, Aandahl EM, Taskén K. Molecular architecture of signal complexes regulating immune cell function. Handb Exp Pharmacol 2008:327-63. [PMID: 18491059 DOI: 10.1007/978-3-540-72843-6_14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Signals transmitted via multichain immunoreceptors control the development, differentiation and activation of hematopoetic cells. The cytoplasmic parts of these receptors contain immunoreceptor tyrosine-based activation motifs (ITAMs) that upon phosphorylation by members of the Src tyrosine kinase family orchestrate a complex set of signaling events involving tyrosine phosphorylation, generation of second messengers like DAG, IP3 and Ca2+, activation of effector molecules like Ras and MAPKs and the translocation and activation of transcription factors like NFAT, API and NF-kB. Spatial and temporal organization of these signaling events is essential both to connect the receptors to downstream cascades as well as to control the functional outcome of the immune activation. Throughout this process control and fine-tuning of the different signals are necessary both for effective immune function and in order to avoid inappropriate or exaggerated immune activation and autoimmunity. This control includes modulating mechanisms that set the threshold for activation and reset the activation status after an immune response has been launched. One immunomodulating pathway is the cAMP-protein kinase A-Csk pathway scaffolded by a supramolecular complex residing in lipid rafts with the A kinase-anchoring protein (AKAP) ezrin, the Csk-binding protein PAG and a linker between the two, EBP50. Failure of correct scaffolding and loss of spatiotemporal control can potentially have severe consequences, leading to immune failure or autoimmunity. The clinical relevance of supramolecular complexes specifically organized by scaffolding proteins in regulating immune activity and the specter of genetic diseases linked to different signaling components suggest that protein-protein contact surfaces can be potential targets for drug intervention. It is also of interest to note that different pathogens have evolved strategies to specifically modulate signal integration, thereby rewiring the signal in a way beneficial for their survival. In addition to demonstrating the importance of different signal processes, these adaptations are elegant illustrations of the potential for drug targeting of protein assembly. This chapter reviews some of the important scaffolding events downstream of immunoreceptors with focus on signaling transduction through the T-cell receptor (TCR).
Collapse
Affiliation(s)
- K M Torgersen
- The Biotechnology Centre of Oslo, Gaustadalléen 21, PO Box 1125 Blindern, Oslo, Norway
| | | | | |
Collapse
|
125
|
Abstract
More than a quarter of a century has passed since the observation that T cells rapidly polarize their actin and microtubule cytoskeletal systems toward antigen-presenting cells during activation. Since this initial discovery, several receptors on T cells (e.g., T cell receptor [TCR], co-receptors, integrins, and chemokine receptors) have been identified to regulate these two cytoskeletal networks through complex signaling pathways, which are still being elucidated. There is now an undeniable body of biochemical, pharmacological, and genetic evidence indicating that regulators of actin and microtubule dynamics are crucial for T cell activation and effector functions. In fact, the actin cytoskeleton participates in the initial clustering of TCR-major histocompatibility complex or peptide complexes, formation and stabilization of the immune synapse, integrin-mediated adhesion, and receptor sequestration, whereas both the actin and microtubule cytoskeletons regulate the establishment of cell polarity, cell migration, and directed secretion of cytokines and cytolytic granules. Over the past several years, we have begun to more thoroughly understand the contributions of specific actin-regulatory and actin-nucleating proteins that govern these processes. Herein, we discuss our current understanding of how activating receptors on T lymphocytes regulate the actin and microtubule cytoskeletons, and how in turn, these distinct but integrated cytoskeletal networks coordinate T cell immune responses.
Collapse
|
126
|
Graham DB, Stephenson LM, Lam SK, Brim K, Lee HM, Bautista J, Gilfillan S, Akilesh S, Fujikawa K, Swat W. An ITAM-signaling pathway controls cross-presentation of particulate but not soluble antigens in dendritic cells. ACTA ACUST UNITED AC 2007; 204:2889-97. [PMID: 17984307 PMCID: PMC2118522 DOI: 10.1084/jem.20071283] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Dendritic cells (DC) possess a unique capacity for presenting exogenous antigen on major histocompatibility class I, a process that is referred to as cross-presentation, which serves a critical role in microbial and tumor immunity. During cross-presentation, antigens derived from pathogen-infected or tumor cells are internalized and processed by DCs for presentation to cytotoxic T lymphocytes (CTLs). We demonstrate that a signaling pathway initiated by the immunoreceptor tyrosine–based activation motif (ITAM)–containing adaptors DAP12 and FcRγ utilizes the Vav family of Rho guanine nucleotide exchange factors (GEFs) for processing and cross-presentation of particulate, but not soluble, antigens by DCs. Notably, this novel pathway is crucial for processing and presentation of particulate antigens, such as those associated with Listeria monocytogenes bacteria, yet it is not required for antigen uptake. Mechanistically, we provide evidence that in DCs, Vav GEFs are essential to link ITAM-dependent receptors with the activation of the NOX2 complex and production of reactive oxygen species (ROS), which regulate phagosomal pH and processing of particulate antigens for cross-presentation. Importantly, we show that genetic disruption of the DAP12/FcRγ–Vav pathway leads to antigen presentation defects that are more profound than in DCs lacking NOX2, suggesting that ITAM signaling also controls cross-presentation in a ROS-independent manner.
Collapse
Affiliation(s)
- Daniel B Graham
- Department of Pathology and Immunology, Washington University School of Medicine and Siteman Cancer Center, St. Louis, MO 63110, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
127
|
RasGRF2, a guanosine nucleotide exchange factor for Ras GTPases, participates in T-cell signaling responses. Mol Cell Biol 2007; 27:8127-42. [PMID: 17923690 DOI: 10.1128/mcb.00912-07] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Ras pathway is critical for the development and function of T lymphocytes. The stimulation of this GTPase in T cells occurs primarily through the Vav1- and phospholipase C-gamma1-dependent activation of RasGRP1, a diacylglycerol-responsive Ras GDP/GTP exchange factor. Here, we show that a second exchange factor, RasGRF2, also participates in T-cell signaling. RasGRF2 is expressed in T cells, translocates to immune synapses, activates Ras, and stimulates the transcriptional factor NF-AT (nuclear factor of activated T cells) through Ras- and phospholipase C-gamma1-dependent routes. T-cell receptor-, Vav1-, and Ca2+-elicited pathways synergize with RasGRF2 for NF-AT stimulation. The analysis of RasGRF2-deficient mice indicates that this protein is required for the induction of bona fide NF-AT targets such as the cytokines tumor necrosis factor alpha and interleukin 2, while it plays minor roles in Ras activation itself. The comparison of lymphocytes from Vav1-/-, Rasgrf2-/-, and Vav1-/-; Rasgrf2-/- mice demonstrates that the RasGRF2 pathway cooperates with the Vav1/RasGRP1 route in the blasting transformation and proliferation of mature T cells. These results identify RasGRF2 as an additional component of the signaling machinery involved in T-cell receptor- and NF-AT-mediated immune responses.
Collapse
|
128
|
Katzav S. Flesh and blood: The story of Vav1, a gene that signals in hematopoietic cells but can be transforming in human malignancies. Cancer Lett 2007; 255:241-54. [PMID: 17590270 DOI: 10.1016/j.canlet.2007.04.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Revised: 04/30/2007] [Accepted: 04/30/2007] [Indexed: 01/08/2023]
Abstract
Cancer results from the interaction of multiple aberrations including activation of dominant oncogenes and upregulation of signal transduction pathways. Identification of the genes involved in malignant transformation is a pre-requisite for understanding cancer and improving its diagnosis and treatment. Quite a few of the genes that have been implicated in cancer are mutant or aberrantly expressed versions of genes that are important mediators of the normal growth that occurs during development. An important example of this is Vav1, a cytoplasmic signal transducer protein initially identified as an oncogene. Physiological expression of Vav1 is restricted to the hematopoietic system, where its best-known function is as a GDP/GTP nucleotide exchange factor for Rho/Rac GTPases, an activity strictly controlled by tyrosine phosphorylation. Vav1 was shown to regulate cytoskeletal rearrangement during activation of hematopoietic cells. Vav1 can also mediate other cellular functions including activation of the JNK, ERK, Ras, NF-kB, and NFAT pathways, in addition to association with numerous adapter proteins such as Shc, NCK, SLP-76, GRB2, and Crk. Although the oncogenic form of Vav1 has not been detected in clinical human tumors, its wild-type form has recently been implicated in mammalian malignancies such as neuroblastoma, melanoma, pancreatic tumors and B-cell chronic lymphocytic leukemia. This review addresses the physiological function of wild-type Vav1, its mode of activation as an oncogene, and its emerging role as a transforming protein in human cancer.
Collapse
Affiliation(s)
- Shulamit Katzav
- The Hubert H. Humphrey center for Experimental Medicine & Cancer Research, The Hebrew University-Hadassah Medical School, P.O. Box 12272, Jerusalem 91120, Israel.
| |
Collapse
|
129
|
Cotta-de-Almeida V, Westerberg L, Maillard MH, Onaldi D, Wachtel H, Meelu P, Chung UI, Xavier R, Alt FW, Snapper SB. Wiskott Aldrich syndrome protein (WASP) and N-WASP are critical for T cell development. Proc Natl Acad Sci U S A 2007; 104:15424-9. [PMID: 17878299 PMCID: PMC2000553 DOI: 10.1073/pnas.0706881104] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although T cell dysfunction and lymphopenia are key features of immunodeficient patients with the Wiskott-Aldrich syndrome and Wiskott-Aldrich syndrome protein (WASP)-deficient mice, T cell development appears relatively normal. We hypothesized that N-WASP, a ubiquitously expressed homologue of WASP, may serve a redundant function with WASP. To examine the unique and redundant activities of WASP and N-WASP, we generated ES cells devoid of WASP and N-WASP [double knockout (DKO)] and used the RAG-2-deficient blastocyst complementation system to generate DKO lymphocytes. Moreover, we mated WASP KO mice with mice containing a conditionally targeted N-WASP allele and used the Cre-loxP system to generate mice lacking WASP and N-WASP in T cells [conditional DKO (cDKO)]. In both systems, N-WASP-deficient cells were indistinguishable from WT cells. In contrast, T cell development in DKO and cDKO mice was markedly altered, as shown by thymic hypocellularity and reduced numbers of peripheral T cells. We found that the combined activity of WASP and N-WASP was important for CD4(-)CD8(-) double-negative (DN)-to-CD4(+)CD8(+) double-positive (DP) cell transition, and this may be partly explained by reduced cycling DN3 cells. In addition, decreased migratory responses of CD4(+)CD8(-) and CD4(-)CD8(+) single-positive (SP) cells and increased percentage of CD69(low)CD24(low) and CD62L(low) SP cells in cDKO cells imply retention of SP cells in the thymus. In summary, this study suggests that, although WASP serves a unique role for peripheral T cell function, T cell development depends on the combined activity of WASP and N-WASP.
Collapse
Affiliation(s)
- Vinicius Cotta-de-Almeida
- *Gastrointestinal Unit
- Center for the Study of Inflammatory Bowel Disease
- Medicine, Harvard Medical School, Boston, MA 02115; and
- Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, RJ, 21045-900, Brazil
| | - Lisa Westerberg
- *Gastrointestinal Unit
- Center for the Study of Inflammatory Bowel Disease
- Medicine, Harvard Medical School, Boston, MA 02115; and
| | - Michel H. Maillard
- *Gastrointestinal Unit
- Center for the Study of Inflammatory Bowel Disease
- Medicine, Harvard Medical School, Boston, MA 02115; and
| | - Dilek Onaldi
- *Gastrointestinal Unit
- Center for the Study of Inflammatory Bowel Disease
- Medicine, Harvard Medical School, Boston, MA 02115; and
| | - Heather Wachtel
- *Gastrointestinal Unit
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114
| | - Parool Meelu
- *Gastrointestinal Unit
- Center for the Study of Inflammatory Bowel Disease
- Medicine, Harvard Medical School, Boston, MA 02115; and
| | | | - Ramnik Xavier
- *Gastrointestinal Unit
- Center for the Study of Inflammatory Bowel Disease
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114
- Medicine, Harvard Medical School, Boston, MA 02115; and
| | - Frederick W. Alt
- **Howard Hughes Medical Institute, Children's Hospital, Boston, MA 02115
- Center for Blood Research, Boston, MA 02115
- Departments of Genetics and
- To whom correspondence may be addressed. E-mail: or
| | - Scott B. Snapper
- *Gastrointestinal Unit
- Center for the Study of Inflammatory Bowel Disease
- Medicine, Harvard Medical School, Boston, MA 02115; and
- To whom correspondence may be addressed. E-mail: or
| |
Collapse
|
130
|
Gomez-Rodriguez J, Readinger JA, Viorritto IC, Mueller KL, Houghtling RA, Schwartzberg PL. Tec kinases, actin, and cell adhesion. Immunol Rev 2007; 218:45-64. [PMID: 17624943 DOI: 10.1111/j.1600-065x.2007.00534.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The Tec family non-receptor tyrosine kinases have been recognized for their roles in the regulation of phospholipase C-gamma and Ca(2+) mobilization downstream from antigen receptors on lymphocytes. Recent data, however, show that the Tec family kinase interleukin-2-inducible T-cell kinase (Itk) also participates in pathways regulating the actin cytoskeleton and 'inside-out' signaling to integrins downstream from the T-cell antigen receptor. Data suggest that Itk may function in a kinase-independent fashion to regulate proper recruitment of the Vav1 guanine nucleotide exchange factor. By enhancing actin cytoskeleton reorganization, recruitment of signaling molecules to the immune synapse, and integrin clustering in response to both antigen and chemokine receptors, the Tec kinases serve as modulators or amplifiers that can increase the duration of T-cell signaling and regulate T-cell functional responses.
Collapse
Affiliation(s)
- Julio Gomez-Rodriguez
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | | | | |
Collapse
|
131
|
Stephenson LM, Sammut B, Graham DB, Chan-Wang J, Brim KL, Huett AS, Miletic AV, Kloeppel T, Landry A, Xavier R, Swat W. DLGH1 is a negative regulator of T-lymphocyte proliferation. Mol Cell Biol 2007; 27:7574-81. [PMID: 17724087 PMCID: PMC2169038 DOI: 10.1128/mcb.00439-07] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Discs large homolog 1 (DLGH1), a founding member of the membrane-associated guanylate kinase family of proteins containing PostSynaptic Density-95/Discs large/Zona Occludens-1 domains, is an ortholog of the Drosophila tumor suppressor gene Discs large. In the mammalian embryo, DLGH1 is essential for normal urogenital morphogenesis and the development of skeletal and epithelial structures. Recent reports also indicate that DLGH1 may be a critical mediator of signals triggered by the antigen receptor complex in T lymphocytes by functioning as a scaffold coordinating the activities of T-cell receptor (TCR) signaling proteins at the immune synapse. However, it remains unclear if DLGH1 functions to enhance or attenuate signals emanating from the TCR. Here, we used Dlgh1 gene-targeted mice to determine the requirement for DLGH1 in T-cell development and activation. Strikingly, while all major subsets of T cells appear to undergo normal thymic development in the absence of DLGH1, peripheral lymph node Dlgh1(-/-) T cells show a hyper-proliferative response to TCR-induced stimulation. These data indicate that, consistent with the known function of Discs large proteins as tumor suppressors and attenuators of cell division, in T lymphocytes, DLGH1 functions as a negative regulator of TCR-induced proliferative responses.
Collapse
Affiliation(s)
- Linda M Stephenson
- Department of Pathology and Immunology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
132
|
Gagnaire B, Gay M, Huvet A, Daniel JY, Saulnier D, Renault T. Combination of a pesticide exposure and a bacterial challenge: in vivo effects on immune response of Pacific oyster, Crassostrea gigas (Thunberg). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2007; 84:92-102. [PMID: 17628715 DOI: 10.1016/j.aquatox.2007.06.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Revised: 06/04/2007] [Accepted: 06/05/2007] [Indexed: 05/16/2023]
Abstract
To assess the impact of pollution induced by pesticides on Pacific oyster, Crassostrea gigas, health in France, in vivo effects of combined pesticide exposure and bacterial challenge on cell activities and gene expression in hemocytes were tested using flow cytometry and real-time PCR. As a first step, an in vivo model of experimental contamination was developed. Pacific oysters were exposed to a mixture of eight pesticides (atrazine, glyphosate, alachlor, metolachlor, fosetyl-alumimium, terbuthylazine, diuron and carbaryl) at environmentally relevant concentrations over a 7-day period. Hemocyte parameters (cell mortality, enzyme activities and phagocytosis) were monitored using flow cytometry and gene expression was evaluated by real-time PCR (RT-PCR). The expression of 19 genes involved in C. gigas hemocyte functions was characterized using RT-PCR. After 7 days of exposure, phagocytosis was significantly reduced and the 19 selected genes were down-regulated in treated animals. As a second step, the experimental contamination method previously developed was used to study interactions between pesticide exposure and bacterial challenge by intramuscular injection of two Vibrio splendidus-related pathogenic strains. Oyster mortality and expression of 10 of the 19 selected genes were followed 4 and 24h post-injection. Oyster mortality was higher in pesticide-treated oysters compared to untreated oysters after the bacterial challenge. Gene expression was up-regulated in pesticide-treated oysters compared to untreated oysters after the bacterial challenge. We hypothesize that gene over-expression due to an interaction between pesticides and bacteria could lead to an injury of host tissues, resulting in higher mortality rates. In conclusion, this study is the first to show effects of pesticides at environmentally relevant concentrations on C. gigas hemocytes and to hypothesize that pesticides modulate the immune response to a bacterial challenge in oysters.
Collapse
Affiliation(s)
- Beatrice Gagnaire
- Ifremer La Tremblade, Laboratoire de Génétique et Pathologie (LGP), 17390 La Tremblade, France.
| | | | | | | | | | | |
Collapse
|
133
|
Abstract
Guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) regulate the activity of small guanine nucleotide-binding (G) proteins to control cellular functions. In general, GEFs turn on signaling by catalyzing the exchange from G-protein-bound GDP to GTP, whereas GAPs terminate signaling by inducing GTP hydrolysis. GEFs and GAPs are multidomain proteins that are regulated by extracellular signals and localized cues that control cellular events in time and space. Recent evidence suggests that these proteins may be potential therapeutic targets for developing drugs to treat various diseases, including cancer.
Collapse
Affiliation(s)
- Johannes L Bos
- Department of Physiological Chemistry and Centre of Biomedical Genetics, UMC Utrecht Universiteitsweg 100, 3584 CG Utrecht, The Netherlands.
| | | | | |
Collapse
|
134
|
Wang S, Diao H, Guan Q, Jevnikar AM, Du C. Enhanced cardiac allograft survival by Vav1-Rac signaling blockade in a mouse model. Transpl Immunol 2007; 18:53-61. [PMID: 17584603 DOI: 10.1016/j.trim.2007.03.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 03/12/2007] [Accepted: 03/23/2007] [Indexed: 12/27/2022]
Abstract
BACKGROUND Vav1-Rac signaling plays a pivotal role in TCR/antigen and CD28 signals for T cell activation. However, pharmacological interference of this signaling has not been tested in the prevention of alloimmune-mediated allograft rejection. It has been demonstrated that 6-thio-GTP, a metabolite of azathioprine, specifically inhibits Vav1-Rac activity in T lymphocytes. Here we show the immunosuppressive efficacy of 6-thio-GTP in the prevention of cardiac allograft rejection. METHODS T cell proliferations were measured by (3)H-thymidine uptake. The immunosuppressive activities of 6-thio-GTP were tested in the cardiac allograft model of C57BL/6 (H-2(b)) to Balb/c (H-2(d)) mice. RESULTS 6-Thio-GTP inhibited TCR/alloantigen stimulated T cell proliferation and CD28-dependent T cell survival. Administration of 6-thio-GTP (0.5 mg/kg) prolonged graft survival to 13.8+/-2.39 days compared to 8.3+/-0.48 days in PBS controls (p<0.0001). Combination of 6-thio-GTP (0.5 mg/kg) with CsA (15 mg/kg) enhanced graft survival from 15.0+/-1.61 days in CsA treated recipients to 36.8+/-2.17 days in those received 20 days of combination therapy of CsA and 6-thio-GTP (p<0.0001), or to 42.7+/-16.63 days in the group treated with 20 days of CsA and 60 days of 6-thio-GTP (p<0.0001). Lymphocytes from 6-thio-GTP treated recipients with long-term surviving grafts (>60 days) displayed reduced proliferative response to alloantigen and higher frequencies of regulatory T cells (Treg). CONCLUSION Vav1-Rac inhibitor 6-thio-GTP prolongs allograft survival alone or in combination with CsA by suppression of alloreactive T cell activation. Our findings suggest the therapeutic potential of pharmacological interference of Vav1-Rac signaling for transplantation.
Collapse
Affiliation(s)
- Shuang Wang
- Department of Medicine, The University of Western Ontario, London, Ontario, Canada
| | | | | | | | | |
Collapse
|
135
|
Miletic AV, Graham DB, Montgrain V, Fujikawa K, Kloeppel T, Brim K, Weaver B, Schreiber R, Xavier R, Swat W. Vav proteins control MyD88-dependent oxidative burst. Blood 2007; 109:3360-8. [PMID: 17158234 PMCID: PMC1852252 DOI: 10.1182/blood-2006-07-033662] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Accepted: 11/30/2006] [Indexed: 12/20/2022] Open
Abstract
The importance of reactive oxygen intermediate (ROI) production in antimicrobial responses is demonstrated in human patients who suffer from chronic granulomatous disease (CGD) due to defective NADPH oxidase function. Exactly how bacterial products activating Toll-like receptors (TLRs) induce oxidative burst is unknown. Here, we identify the Vav family of Rho guanine nucleotide exchange factors (GEFs) as critical mediators of LPS-induced MyD88-dependent activation of Rac2, NADPH oxidase, and ROI production using mice deficient in Vav1, Vav2, and Vav3. Vav proteins are also required for p38 MAPK activation and for normal regulation of proinflammatory cytokine production, but not for other MyD88-controlled effector pathways such as those involving JNK, COX2, or iNOS and the production of reactive nitrogen intermediates (RNIs). Thus, our data indicate that Vav specifically transduces a subset of signals emanating from MyD88.
Collapse
Affiliation(s)
- Ana V Miletic
- Department of Pathology and Immunology, Washington University School of Medicine and Siteman Cancer Center, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
136
|
Weckbecker G, Bruns C, Fischer KD, Heusser C, Li J, Metzler B, Morris RE, Nuesslein-Hildesheim B, Raulf F, Wieczorek G, Zenke G. Strongly reduced alloreactivity and long-term survival times of cardiac allografts in Vav1- and Vav1/Vav2-knockout mice. Transpl Int 2007; 20:353-64. [PMID: 17326776 DOI: 10.1111/j.1432-2277.2006.00438.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Vav proteins mediate T- and B-cell activation by functioning as GTP/GDP exchange factors for small GTPases. We have studied the role of Vav1 and Vav2 in allogeneic T-cell activation, antibody responses and allograft rejection. Alloantigen-induced proliferation of T cells from Vav1- and Vav1/Vav2-knockout (ko) mice was decreased by >90% in a mixed lymphocyte reaction. In whole-blood cultures, Vav deficiency led to markedly impaired T- and B-cell activation. Expansion of Vav1- or Vav1/Vav2-ko T cells (C57BL/6) was reduced after transfer into severe combined immune deficiency/beige recipient mice (BALB/c). After priming with 2,4-dinitrophenyl (DNP)-keyhole limpet hemocyanin, T-cell-dependent anti-DNP IgM and IgG antibody levels were normal in Vav1-ko mice but undetectable in Vav1/Vav2-ko mice. The median survival time of BALB/c cardiac allografts transplanted into C57BL/6 Vav1-ko mice (n = 13) or Vav1/Vav2-ko mice (n = 5) was >100 and >77 days, compared with 8-9 days in the corresponding wild-type mice. Vav1/Vav2-ko mice with <100 days graft survival developed bacterial skin infections and were prematurely killed with beating cardiac allograft. Long-term surviving transplants of single and double ko mice showed mild cellular interstitial rejection and mild to severe vascular remodeling. In conclusion, our studies show for the first time that the absence of Vav1 and Vav1/Vav2 in ko mice strongly reduces alloreactivity and results in long-term allograft survival, whereas antibody responses were only affected in Vav1/Vav2 ko mice.
Collapse
Affiliation(s)
- Gisbert Weckbecker
- Autoimmunity and Transplantation, Novartis Institutes for BioMedical Research, Novartis Pharma AG, Basel, Switzerland.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
137
|
Hayday AC, Pennington DJ. Key factors in the organized chaos of early T cell development. Nat Immunol 2007; 8:137-44. [PMID: 17242687 DOI: 10.1038/ni1436] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Accepted: 12/12/2006] [Indexed: 11/09/2022]
Abstract
A fundamental issue in T cell development is what controls whether a thymocyte differentiates into a gammadelta T cell or an alphabeta T cell, each defined by their distinct T cell receptor. Most likely, lessons learned in studying that issue will also provide insight into how the thymus produces T cell subsets with distinct functional and regulatory potentials. Here we review recent experiments, focusing on three factors that regulate thymocyte differentiation up to and including the expression of the first products of antigen receptor gene rearrangements. Those factors are the archetypal developmental regulator Notch, intrinsic signals emanating from antigen-receptor complexes, and trans conditioning, which reflects communication between different subsets of thymocytes. We also review new findings on the positive selection of gammadelta T cells and on extrathymic T cell development.
Collapse
Affiliation(s)
- Adrian C Hayday
- King's College School of Medicine at Guy's Hospital, London SE1 9RT, UK
| | | |
Collapse
|
138
|
Pearce AC, McCarty OJT, Calaminus SDJ, Vigorito E, Turner M, Watson SP. Vav family proteins are required for optimal regulation of PLCgamma2 by integrin alphaIIbbeta3. Biochem J 2007; 401:753-61. [PMID: 17054426 PMCID: PMC1770845 DOI: 10.1042/bj20061508] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Vav proteins belong to the family of guanine-nucleotide-exchange factors for the Rho/Rac family of small G-proteins. In addition, they serve as important adapter proteins for the activation of PLCgamma (phospholipase Cgamma) isoforms by ITAM (immunoreceptor tyrosine-based activation motif) receptors, including the platelet collagen receptor GPVI (glycoprotein VI). Vav proteins are also regulated downstream of integrins, including the major platelet integrin alphaIIbbeta3, which has recently been shown to regulate PLCgamma2. In the present study, we have investigated the role of Vav family proteins in filopodia and lamellipodia formation on fibrinogen using platelets deficient in Vav1 and Vav3. Wild-type mouse platelets undergo a limited degree of spreading on fibrinogen, characterized by the formation of numerous filopodia and limited lamellipodia structures. Platelets deficient in Vav1 and Vav3 exhibit reduced filopodia and lamellipodia formation during spreading on fibrinogen. This is accompanied by reduced alphaIIbbeta3-mediated PLCgamma2 tyrosine phosphorylation and reduced Ca(2+) mobilization. In contrast, the G-protein agonist thrombin stimulates full spreading of control and Vav1/3-deficient platelets. Consistent with this, stimulation of F-actin (filamentous actin) formation and Rac activation by thrombin is not altered in Vav-deficient cells. These results demonstrate that Vav1 and Vav3 are required for optimal spreading and regulation of PLCgamma2 by integrin alphaIIbbeta3, but that their requirement is by-passed upon G-protein receptor activation.
Collapse
Affiliation(s)
- Andrew C Pearce
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, Division of Medical Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| | | | | | | | | | | |
Collapse
|
139
|
Charvet C, Canonigo AJ, Bécart S, Maurer U, Miletic AV, Swat W, Deckert M, Altman A. Vav1 promotes T cell cycle progression by linking TCR/CD28 costimulation to FOXO1 and p27kip1 expression. THE JOURNAL OF IMMUNOLOGY 2007; 177:5024-31. [PMID: 17015685 DOI: 10.4049/jimmunol.177.8.5024] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Vav proteins play a critical role in T cell activation and proliferation by promoting cytoskeleton reorganization, transcription factor activation, and cytokine production. In this study, we investigated the role of Vav in T cell cycle progression. TCR/CD28-stimulated Vav1(-/-) T cells displayed a cell cycle block at the G0-G1 stage, which accounted for their defective proliferation. This defect was associated with impaired TCR/CD28-induced phosphorylation of Akt and the Forkhead family transcription factor, FOXO1. The cytoplasmic localization of FOXO1 and its association with 14-3-3tau were also reduced in Vav1(-/-) T cells. Consistent with the important role of FOXO1 in p27 kip1 transcription, stimulated Vav1(-/-) T cells failed to down-regulate the expression of p27 kip1, explaining their G0-G1 arrest. These defects were more pronounced in Vav1/Vav3 double-deficient T cells, suggesting partial redundancy between Vav1 and Vav3. Importantly, IL-2-induced p27 kip1 down-regulation and cyclin D3 up-regulation and FOXO1 phosphorylation were similar in Vav1(-/-) and wild-type T lymphoblasts, indicating that defective FOXO1 phosphorylation and p27 kip1 and cyclin D3 expression do not result from deficient IL-2 signaling in the absence of Vav1. Thus, Vav1 is a critical regulator of a PI3K/Akt/FOXO1 pathway, which controls T cell cycle progression and proliferation.
Collapse
Affiliation(s)
- Céline Charvet
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA
| | | | | | | | | | | | | | | |
Collapse
|
140
|
Gazit R, Aker M, Elboim M, Achdout H, Katz G, Wolf DG, Katzav S, Mandelboim O. NK cytotoxicity mediated by CD16 but not by NKp30 is functional in Griscelli syndrome. Blood 2007; 109:4306-12. [PMID: 17255357 DOI: 10.1182/blood-2006-09-047159] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Abstract
Griscelli syndrome (GS) type 2 is an autosomal recessive disorder represented by pigment dilution and impaired cytotoxic T lymphocyte (CTL) activity. NK activity has been scarcely investigated in GS patients. Here, we describe a new patient, possessing a hemophagocytic syndrome with a homozygous Q118X nonsense RAB27A mutation. Single specific primer–polymerase chain reaction (SSP-PCR) was developed based on this mutation and is currently used in prenatal genetic analysis. As expected, CTLs in the patient are not functional and NK cytotoxicity against K562 or 721.221 cells is diminished. Surprisingly, however, we demonstrate that CD16-mediated killing is intact in this patient and is therefore RAB27A independent, whereas NKp30-mediated killing is impaired and is therefore RAB27A dependent. We further analyzed the signaling pathways of these 2 receptors and demonstrated phosphorylation of Vav1 after CD16 activation but not after NKp30 engagement. Thus, we identify a novel homozygous mutation in the RAB27A gene of a new GS patient, observe for the first time that some activating NK receptors function in GS patients, and demonstrate a functional dichotomy in the killing mediated by these human NK-activating receptors.
Collapse
Affiliation(s)
- Roi Gazit
- The Lautenberg Center for General and Tumor Immunology, Hadassah Medical School, Jerusalem, Israel
| | | | | | | | | | | | | | | |
Collapse
|
141
|
Sauzeau V, Jerkic M, López-Novoa JM, Bustelo XR. Loss of Vav2 proto-oncogene causes tachycardia and cardiovascular disease in mice. Mol Biol Cell 2007; 18:943-52. [PMID: 17202406 PMCID: PMC1805112 DOI: 10.1091/mbc.e06-09-0877] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The Vav family is a group of signal transduction molecules that activate Rho/Rac GTPases during cell signaling. Experiments using knockout mice have indicated that the three Vav proteins present in mammals (Vav1, Vav2, and Vav3) are essential for proper signaling responses in hematopoietic cells. However, Vav2 and Vav3 are also highly expressed in nonhematopoietic tissues, suggesting that they may have additional functions outside blood cells. Here, we report that this is the case for Vav2, because the disruption of its locus in mice causes tachycardia, hypertension, and defects in the heart, arterial walls, and kidneys. We also provide physiological and pharmacological evidence demonstrating that the hypertensive condition of Vav2-deficient mice is due to a chronic stimulation of the renin/angiotensin II and sympathetic nervous systems. Together, these results indicate that Vav2 plays crucial roles in the maintenance of cardiovascular homeostasis in mice.
Collapse
Affiliation(s)
- Vincent Sauzeau
- *Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer and
| | - Mirjana Jerkic
- Departamento de Fisiología y Farmacología, Consejo Superior de Investigaciones Científicas, University of Salamanca, E-37007 Salamanca, Spain
| | - José M. López-Novoa
- Departamento de Fisiología y Farmacología, Consejo Superior de Investigaciones Científicas, University of Salamanca, E-37007 Salamanca, Spain
| | - Xosé R. Bustelo
- *Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer and
| |
Collapse
|
142
|
Anastasiadis PZ. p120-ctn: A nexus for contextual signaling via Rho GTPases. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:34-46. [PMID: 17028013 DOI: 10.1016/j.bbamcr.2006.08.040] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Revised: 08/24/2006] [Accepted: 08/27/2006] [Indexed: 01/11/2023]
Abstract
p120 catenin (p120) is the prototypic member of a subfamily of armadillo repeat domain proteins involved in intercellular adhesion. Recent evidence indicates that p120 associates with classical cadherins and regulates their stability. Ectopic p120 expression results in a variety of morphological effects, and promotes cell migration. There is now strong evidence that p120 acts, at least in part, through regulation of Rho GTPases. The data suggest that p120 may act as a signaling nexus, conveying messages from the cellular micro- and macro-environment to the cell's interior. By regulating Rho GTPases in a context-dependent manner p120 can exert profound effects on cellular responses from synaptic plasticity to vesicle trafficking, as well as regulate the motile vs. sessile, and possibly the proliferative vs. quiescent phenotype of epithelial cells. Here, we review the new evidence on the relationship of p120 to Rho GTPases, and discuss potential roles for the p120-Rho connection in normal and malignant cells.
Collapse
Affiliation(s)
- Panos Z Anastasiadis
- Department Cancer Biology, Mayo Clinic Comprehensive Cancer Center, Griffin Cancer Research Building, Rm. 307, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
| |
Collapse
|
143
|
Abstract
Signal transduction events leading to the survival, differentiation, or apoptosis of cells of the innate or adaptive immune system must be properly coordinated to ensure the normal mounting and termination of immune responses. One of the key transcription factors in immune responses is nuclear factor kappaB (NF-kappaB), which has been the focus of intense investigation over the past two decades. With the identification of the CARMA1-BCL10-MALT1 complex and ongoing progress in understanding the molecular mechanisms connecting T cell and B cell receptor proximal signals to the IkappaB kinase (IKK) complex, a cohesive model of antigen receptor (AgR)-dependent signaling to NF-kappaB activation is beginning to emerge. In this review, we provide an overview of the current state of research into the mechanisms that regulate AgR-mediated NF-kappaB transcriptional activity, with particular focus on the events leading to activation of the IKK complex.
Collapse
Affiliation(s)
- Jan Schulze-Luehrmann
- Section of Immunobiology and Department of Molecular Biophysics & Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | | |
Collapse
|
144
|
Utomo A, Cullere X, Glogauer M, Swat W, Mayadas TN. Vav proteins in neutrophils are required for FcgammaR-mediated signaling to Rac GTPases and nicotinamide adenine dinucleotide phosphate oxidase component p40(phox). THE JOURNAL OF IMMUNOLOGY 2006; 177:6388-97. [PMID: 17056570 DOI: 10.4049/jimmunol.177.9.6388] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Phagocytes generate reactive oxygen species, the regulation of which is important in eliminating ingested microbes while limiting tissue damage. Clustering of FcgammaRs results in the activation of Vav proteins, Rho/Rac guanine nucleotide exchange factors, and results in robust superoxide generation through the NADPH oxidase. In this study, studies in neutrophils isolated from mice deficient in Vav or Rac isoforms demonstrate a critical role for Vav3 in Rac2-dependent activation of the NADPH oxidase following FcgammaR clustering. However, studies in cytokine-primed cells revealed a strict requirement for Vav1 and Vav3 and Rac1 and Rac2 in the FcgammaR-mediated oxidative burst. In comparison, Vav was not essential for PMA or G protein-coupled receptor-mediated superoxide generation. The FcgammaR-mediated oxidative burst defect in Vav-deficient cells was linked to aberrant Rac activation as well as Rac- and actin-polymerization-independent, but PI3K-dependent, phosphorylation of the NADPH oxidase component p40(phox). In macrophages, Vav regulation of Rac GTPases was required specifically in FcgammaR-mediated activation of the oxidative burst, but not in phagocytosis. Thus, Vav proteins specifically couple FcgammaR signaling to NADPH oxidase function through a Rac-dependent as well as an unexpected Rac-independent signal that is proximal to NADPH oxidase activation and does not require actin polymerization.
Collapse
Affiliation(s)
- Ahmad Utomo
- Center of Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | | | | | | | | |
Collapse
|
145
|
Sakai H, Chen Y, Itokawa T, Yu KP, Zhu ML, Insogna K. Activated c-Fms recruits Vav and Rac during CSF-1-induced cytoskeletal remodeling and spreading in osteoclasts. Bone 2006; 39:1290-301. [PMID: 16950670 DOI: 10.1016/j.bone.2006.06.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 05/30/2006] [Accepted: 06/17/2006] [Indexed: 12/13/2022]
Abstract
Colony-stimulating factor-1 (CSF-1) induces osteoclast spreading that requires activation of c-Src and phosphatidyl inositol 3-kinase (PI3-K), both of which are recruited to activated c-Fms, the CSF-1 receptor. The present report provides evidence that the hemopoietic guanine nucleotide exchange factor (GEF), Vav, and its target GTPase, Rac, lie downstream from this initial signaling complex. CSF-1 treatment of osteoclast-like cells induced translocation of Vav to the plasma membrane, an increase in its phosphotyrosine content, and a concomitant decline in the amount of phosphoinositol 4,5-bisphosphate bound to Vav, changes known to induce Vav's GEF activity. CSF-1 induced the association of Vav and Rac and increased Rac's GTPase activity. CSF-1 also induced rapid translocation of Rac to the periphery of spreading neonatal rat osteoclasts where it co-localized primarily with Vav3 and to a lesser extent with Vav1. Wortmannin, an inhibitor of PI3-K, blocked CSF-1-induced Rac translocation and prevented CSF-1-induced spreading and actin reorganization in osteoclasts. CSF-1-induced osteoclast spreading was not significantly reduced in osteoclasts isolated from Vav1 knock-out mice and Vav1 knock-out mice had normal bone density. Microinjection of constitutively active Rac, but not constitutively active Cdc42 or RhoA, induced lamellipodia formation and osteoclast spreading, mimicking the effects of CSF-1. Dominant-negative Rac blocked CSF-1-induced osteoclast spreading, whereas neither dominant-negative Cdc42 nor C3, an inhibitor of RhoA, affected the response to CSF-1. These data demonstrate that Vav and Rac lie downstream from activated PI3-K in CSF-1-treated osteoclasts and that Rac is required for CSF-1-induced cytoskeletal remodeling in these cells.
Collapse
Affiliation(s)
- Hiroaki Sakai
- Yale School of Medicine, TAC S-133, PO Box 208020, New Haven, CT 06520-8020, USA. hiro_yale.@yahoo.co.jp
| | | | | | | | | | | |
Collapse
|
146
|
Stephenson LM, Miletic AV, Kloeppel T, Kusin S, Swat W. Vav Proteins Regulate the Plasma Cell Program and Secretory Ig Production. THE JOURNAL OF IMMUNOLOGY 2006; 177:8620-5. [PMID: 17142761 DOI: 10.4049/jimmunol.177.12.8620] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Plasma cell (PC) development is initiated following B cell activation and controlled by a B lymphocyte-induced maturation protein (Blimp)-1-dependent program involving the concerted action of several proplasma transcriptional regulators. However, the factors that control Blimp-1 expression remain largely unknown. In this context, mice deficient for all three of the Vav family of proteins (Vav(null)) develop substantial B cell populations, including marginal zone B cells, yet have a virtual absence of serum Igs, indicating that Vav may be specifically required in PC development and Ig production. We show in this study that mature marginal zone B cells from Vav(null) mice proliferate following stimulation with TLR ligands but exhibit severe defects in PC differentiation and Ig secretion. Under conditions inducing PC differentiation, Vav(null) B cells fail to efficiently induce Blimp-1, X box-binding protein-1, J chain, or secretory Ig mu transcripts but express IFN-regulatory factor-4 at levels similar to wild-type cells. These data indicate a previously unknown role for Vav as an upstream regulator of Blimp-1.
Collapse
Affiliation(s)
- Linda M Stephenson
- Department of Pathology and Immunology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | | | | | | | | |
Collapse
|
147
|
Miletic AV, Sakata-Sogawa K, Hiroshima M, Hamann MJ, Gomez TS, Ota N, Kloeppel T, Kanagawa O, Tokunaga M, Billadeau DD, Swat W. Vav1 acidic region tyrosine 174 is required for the formation of T cell receptor-induced microclusters and is essential in T cell development and activation. J Biol Chem 2006; 281:38257-65. [PMID: 17050525 PMCID: PMC1876972 DOI: 10.1074/jbc.m608913200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vav proteins are multidomain signaling molecules critical for mediating signals downstream of several surface receptors, including the antigen receptors of T and B lymphocytes. The catalytic guanine nucleotide exchange factor (GEF) activity of the Vav Dbl homology (DH) domain is thought to be controlled by an intramolecular autoinhibitory mechanism involving an N-terminal extension and phosphorylation of tyrosine residues in the acidic region (AC). Here, we report that the sequences surrounding the Vav1 AC: Tyr(142), Tyr(160), and Tyr(174) are evolutionarily conserved, conform to consensus SH2 domain binding motifs, and bind several proteins implicated in TCR signaling, including Lck, PI3K p85alpha, and PLCgamma1, through direct interactions with their SH2 domains. In addition, the AC tyrosines regulate tyrosine phosphorylation of Vav1. We also show that Tyr(174) is required for the maintenance of TCR-signaling microclusters and for normal T cell development and activation. In this regard, our data demonstrate that while Vav1 Tyr(174) is essential for maintaining the inhibitory constraint of the DH domain in both developing and mature T cells, constitutively activated Vav GEF disrupts TCR-signaling microclusters and leads to defective T cell development and proliferation.
Collapse
Affiliation(s)
- Ana V. Miletic
- From the Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, the
| | - Kumiko Sakata-Sogawa
- Research Unit for Single Molecule Immunoimaging, RIKEN Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan, the
| | - Michio Hiroshima
- Research Unit for Single Molecule Immunoimaging, RIKEN Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan, the
| | - Michael J. Hamann
- Department of Immunology and Division of Oncology Research, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, the
| | - Timothy S. Gomez
- Department of Immunology and Division of Oncology Research, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, the
| | - Naruhisa Ota
- Laboratory for Autoimmune Regulation, RIKEN Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan, and the
| | - Tracie Kloeppel
- From the Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, the
| | - Osami Kanagawa
- Laboratory for Autoimmune Regulation, RIKEN Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan, and the
| | - Makio Tokunaga
- Research Unit for Single Molecule Immunoimaging, RIKEN Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan, the
- Structural Biology Center, National Institute of Genetics, and Department of Genetics, Graduate University for Advanced Studies, Mishima, Shizuoka 411-8540, Japan
| | - Daniel D. Billadeau
- Department of Immunology and Division of Oncology Research, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, the
| | - Wojciech Swat
- From the Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, the
- To whom correspondence should be addressed: Dept. of Pathology and Immunology, WA University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110. Tel.: 314-747-8886; Fax: 314-362-4096; E-mail:
| |
Collapse
|
148
|
Gu Y, Chae HD, Siefring JE, Jasti AC, Hildeman DA, Williams DA. RhoH GTPase recruits and activates Zap70 required for T cell receptor signaling and thymocyte development. Nat Immunol 2006; 7:1182-90. [PMID: 17028588 DOI: 10.1038/ni1396] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2006] [Accepted: 08/25/2006] [Indexed: 11/09/2022]
Abstract
RhoH is a hematopoietic-specific, GTPase-deficient member of the Rho GTPase family with unknown physiological function. Here we demonstrate that Rhoh-/- mice have impaired T cell receptor (TCR)-mediated thymocyte selection and maturation, resulting in T cell deficiency. RhoH deficiency resulted in defective CD3zeta phosphorylation, impaired translocation of the signaling molecule Zap70 to the immunological synapse and reduced activation of Zap70-mediated signaling in thymic and peripheral T cells. Proteomic analyses demonstrated that RhoH is a component of TCR signaling and is required for recruitment of Zap70 to the TCR through interaction with RhoH noncanonical immunoreceptor tyrosine-based activation motifs (ITAMs). In vivo reconstitution studies also demonstrated that RhoH function depends on phosphorylation of the RhoH ITAMs. These findings suggest that RhoH is a critical regulator of thymocyte development and TCR signaling by mediating recruitment and activation of Zap70.
Collapse
Affiliation(s)
- Yi Gu
- Division of Experimental Hematology, Cincinnati Children's Research Foundation and Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio 45229, USA.
| | | | | | | | | | | |
Collapse
|
149
|
Liu BA, Jablonowski K, Raina M, Arcé M, Pawson T, Nash PD. The human and mouse complement of SH2 domain proteins-establishing the boundaries of phosphotyrosine signaling. Mol Cell 2006; 22:851-868. [PMID: 16793553 DOI: 10.1016/j.molcel.2006.06.001] [Citation(s) in RCA: 220] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 05/19/2006] [Accepted: 06/02/2006] [Indexed: 01/07/2023]
Abstract
SH2 domains are interaction modules uniquely dedicated to the recognition of phosphotyrosine sites and are embedded in proteins that couple protein-tyrosine kinases to intracellular signaling pathways. Here, we report a comprehensive bioinformatics, structural, and functional view of the human and mouse complement of SH2 domain proteins. This information delimits the set of SH2-containing effectors available for PTK signaling and will facilitate the systems-level analysis of pTyr-dependent protein-protein interactions and PTK-mediated signal transduction. The domain-based architecture of SH2-containing proteins is of more general relevance for understanding the large family of protein interaction domains and the modular organization of the majority of human proteins.
Collapse
Affiliation(s)
- Bernard A Liu
- Ben May Institute for Cancer Research and the Committee on Cancer Biology, The University of Chicago, Chicago, Illinois 60637
| | - Karl Jablonowski
- Ben May Institute for Cancer Research and the Committee on Cancer Biology, The University of Chicago, Chicago, Illinois 60637
| | - Monica Raina
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto M5G 1X5, Canada
| | - Michael Arcé
- Ben May Institute for Cancer Research and the Committee on Cancer Biology, The University of Chicago, Chicago, Illinois 60637
| | - Tony Pawson
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto M5G 1X5, Canada.
| | - Piers D Nash
- Ben May Institute for Cancer Research and the Committee on Cancer Biology, The University of Chicago, Chicago, Illinois 60637.
| |
Collapse
|
150
|
Hunter SG, Zhuang G, Brantley-Sieders D, Swat W, Cowan CW, Chen J. Essential role of Vav family guanine nucleotide exchange factors in EphA receptor-mediated angiogenesis. Mol Cell Biol 2006; 26:4830-42. [PMID: 16782872 PMCID: PMC1489141 DOI: 10.1128/mcb.02215-05] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Angiogenesis, the process by which new blood vessels are formed from preexisting vasculature, is critical for vascular remodeling during development and contributes to the pathogenesis of diseases such as cancer. Prior studies from our laboratory demonstrate that the EphA2 receptor tyrosine kinase is a key regulator of angiogenesis in vivo. The EphA receptor-mediated angiogenic response is dependent on activation of Rho family GTPase Rac1 and is regulated by phosphatidylinositol 3-kinase. Here we report the identification of Vav2 and Vav3 as guanine nucleotide exchange factors (GEFs) that link the EphA2 receptor to Rho family GTPase activation and angiogenesis. Ephrin-A1 stimulation recruits the binding of Vav proteins to the activated EphA2 receptor. The induced association of EphA receptor and Vav proteins modulates the activity of Vav GEFs, leading to activation of Rac1 GTPase. Overexpression of either Vav2 or Vav3 in primary microvascular endothelial cells promotes Rac1 activation, cell migration, and assembly in response to ephrin-A1 stimulation. Conversely, loss of Vav2 and Vav3 GEFs inhibits Rac1 activation and ephrin-A1-induced angiogenic responses both in vitro and in vivo. In addition, embryonic fibroblasts derived from Vav2-/- Vav3-/- mice fail to spread on an ephrin-A1-coated surface and exhibit a significant decrease in the formation of ephrin-A1-induced lamellipodia and filopodia. These findings suggest that Vav GEFs serve as a molecular link between EphA2 receptors and the actin cytoskeleton and provide an important mechanism for EphA2-mediated angiogenesis.
Collapse
Affiliation(s)
- Sonja G Hunter
- Vanderbilt University School of Medicine, A-4323 MCN, 1161 21st Avenue South, Nashville, TN 37232-2363, USA
| | | | | | | | | | | |
Collapse
|