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Ruiz-Rodado V, Dowdy T, Lita A, Kramp T, Zhang M, Jung J, Dios-Esponera A, Zhang L, Herold-Mende CC, Camphausen K, Gilbert MR, Larion M. Cysteine is a limiting factor for glioma proliferation and survival. Mol Oncol 2021; 16:1777-1794. [PMID: 34856072 PMCID: PMC9067152 DOI: 10.1002/1878-0261.13148] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 10/25/2021] [Accepted: 11/30/2021] [Indexed: 11/06/2022] Open
Abstract
Nutritional intervention is becoming more prevalent as adjuvant therapy for many cancers in view of the tumor dependence on external sources for some nutrients. However, little is known about the mechanisms that make cancer cells require certain nutrients from the microenvironment. Herein, we report the dependence of glioma cells on exogenous cysteine/cystine, despite this amino acid being nonessential. Using several 13C‐tracers and analysis of cystathionine synthase and cystathioninase levels, we revealed that glioma cells were not able to support glutathione synthesis through the transsulfuration pathway, which allows methionine to be converted to cysteine in cysteine/cystine‐deprived conditions. Therefore, we explored the nutritional deprivation in a mouse model of glioma. Animals subjected to a cysteine/cystine‐free diet survived longer, although this increase did not attain statistical significance, with concomitant reductions in plasma glutathione and cysteine levels. At the end point, however, tumors displayed the ability to synthesize glutathione, even though higher levels of oxidative stress were detected. We observed a compensation from the nutritional intervention revealed as the recovery of cysteine‐related metabolite levels in plasma. Our study highlights a time window where cysteine deprivation can be exploited for additional therapeutic strategies.
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Affiliation(s)
- Victor Ruiz-Rodado
- Neuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda
| | - Tyrone Dowdy
- Neuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda
| | - Adrian Lita
- Neuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda
| | - Tamalee Kramp
- Radiation Oncology Branch, Center for Cancer Research, National Institutes of Health, Bethesda
| | - Meili Zhang
- Neuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda
| | - Jinkyu Jung
- Neuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda
| | | | - Lumin Zhang
- Neuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda
| | - Christel C Herold-Mende
- Division of Neurosurgical Research, Department of Neurosurgery, University Hospital Heidelberg, Heidelberg, Germany
| | - Kevin Camphausen
- Radiation Oncology Branch, Center for Cancer Research, National Institutes of Health, Bethesda
| | - Mark R Gilbert
- Neuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda
| | - Mioara Larion
- Neuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda
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Rodado VR, Dowdy T, Jung J, Dios-Esponera A, Lita A, Kramp T, Camphausen K, Gilbert M, Larion M. TAMI-53. CYSTEINE IS A LIMITING FACTOR FOR GLIOMA PROLIFERATION AND SURVIVAL. Neuro Oncol 2021. [DOI: 10.1093/neuonc/noab196.836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
BACKGROUND
Little is known about the mechanisms that render cancer cells dependent on certain nutrients from the microenvironment. Cysteine is a non-essential amino acid, since it can be synthetized from methionine through the transsulfuration pathway; moreover, cysteine is also uptake from the diet as cystine. We have investigated the metabolism of cysteine in glioma cell lines, and how cysteine/cystine-deprivation alters their antioxidant response in addition to the effect of this nutrient restriction to viability and proliferation in vitro and in vivo.
METHODS
Cysteine metabolism was investigated through LCMS-based 13C-tracing experiments and the expression levels of key enzymes in the transsulfuration pathway were also explored. Finally, a mouse model of IDH1 mutant glioma was subjected to a cysteine/cystine-free diet and tumor metabolism was analyzed by LCMS.
RESULTS
Herein, we report the dependence of glioma cells on exogenous cysteine/cystine, despite this amino acid being nonessential. Using several 13C-tracers and analysis of cystathionine synthase and cystathioninase levels, we revealed that glioma cells were not able to upregulate the transulfuration pathway cysteine, which allows methionine to be converted to cysteine in cysteine/cystine deprived conditions. We demonstrated that exogenous cysteine/cystine are crucial for glutathione synthesis, and impact growth and viability. Therefore, we explored the nutritional deprivation in a mouse model of glioma. Animals subjected to a cysteine/cystine-free diet survived longer, with concomitant reductions in glutathione and cysteine plasma levels. At the endpoint higher levels of oxidative stress were detected despite the systemic recovery of cysteine-related metabolites in the plasma.
CONCLUSION
The results presented herein reveal an alternative therapeutic approach combining cysteine/cysteine-deprivation diets and treatments involving ROS production by limiting the ability of glioma cells to quench oxidative stress through dietary interventions. Our study highlights a time window where cysteine deprivation can be exploited for additional therapeutic strategies.
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Affiliation(s)
| | - Tyrone Dowdy
- National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jinkyu Jung
- National Institutes of Health, Bethesda, MD, USA
| | | | - Adrian Lita
- National Institutes of Health, Bethesda, MD, USA
| | | | - Kevin Camphausen
- National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Mark Gilbert
- National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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Ruiz-Rodado V, Dowdy T, Yung J, Dios-Esponera A, Lita A, Kramp T, Camphausen K, Gilbert M, Larion M. DDRE-16. CYSTEINE IS AN ESSENTIAL AMINO ACID IN GLIOMAS. Neurooncol Adv 2021. [PMCID: PMC7994370 DOI: 10.1093/noajnl/vdab024.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Cysteine is a non-essential amino acid, since it can be synthetized from methionine through the transsulfuration pathway; moreover, cysteine is also uptake from the diet as cystine. We have investigated the metabolism of cysteine in glioma cell lines, and how cysteine/cystine-deprivation alters their antioxidant response in addition to the effect of this nutrient restriction to viability and proliferation in vitro and in vivo. METHODS Cysteine metabolism was investigated through LCMS-based 13C-tracing experiments involving different probes such as 13C-methyl-Methionine, 13C-C3-Cysteine, 13C-C3,3’-Cystine, 13C-C3-Serine and 13C-U-Glutamine and the expression levels of key enzymes in the transsulfuration pathway were also explored. Finally, a mouse model of IDH1 mutant glioma was subjected to a cysteine/cystine-free diet and tumor metabolism was analyzed by LCMS. RESULTS We demonstrated that exogenous cysteine/cystine are crucial for glutathione synthesis, and impact growth and viability. We also found that methionine cycle is disconnected from the transsulfuration pathway based on 13C-tracing data and protein expression levels of cystathionine synthase and cystathioninase. Accordingly, cysteine-related metabolites such as GSH, involved in REDOX hemostasis, are downregulated, revealing a hypersensitive phenotype to ROS. Animal models upon a cysteine/cystine-free diet experienced an increase in survival and elevated levels of oxidative stress in tumor tissue. CONCLUSION This results presented herein reveal an alternative therapeutic approach combining cysteine/cysteine-deprivation diets and treatments involving ROS production by limiting the ability of glioma cells to quench oxidative stress through dietary interventions.
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Affiliation(s)
| | | | - Jinkyu Yung
- National Cancer Institute, Bethesda, MD, USA
| | | | - Adrian Lita
- National Cancer Institute, Bethesda, MD, USA
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Dios-Esponera A, Melis N, Subramanian BC, Weigert R, Samelson LE. Pak1 Kinase Promotes Activated T Cell Trafficking by Regulating the Expression of L-Selectin and CCR7. Front Immunol 2019; 10:370. [PMID: 30891040 PMCID: PMC6411651 DOI: 10.3389/fimmu.2019.00370] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 02/13/2019] [Indexed: 01/13/2023] Open
Abstract
Normal function of the adaptive immune system requires trafficking of T cells between the blood and lymphoid organs. Lymphocyte homing to lymph nodes requires that they cross endothelial barriers present in blood vessels and lymphatics. This multi-step process requires a remodeling of the lymphocyte plasma membrane, which is mediated by the dynamic re-arrangement of the actin cytoskeleton. Pak1 plays a central role in cell morphology, adhesion and migration in various cell types. Here we demonstrate that Pak1 is required for activated CD4+ T cell trafficking to lymph nodes. Pak1 deficiency in T cells causes a defect in the transcription of CCR7 and L-selectin, thereby altering lymphocyte trafficking. Additionally, we report an increase in L-selectin shedding in Pak1-deficient T cells, which correlates with a decrease in the recruitment of calmodulin to the cytoplasmic tail of L-selectin during T cell activation. Overall, our findings demonstrate that by regulating the expression of two major lymph node homing molecules, L-selectin and CCR7, Pak1 mediates activated CD4+ T cell trafficking.
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Affiliation(s)
- Ana Dios-Esponera
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Nicolas Melis
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Bhagawat C Subramanian
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Roberto Weigert
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Lawrence E Samelson
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
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Guittard G, Dios-Esponera A, Palmer DC, Akpan I, Barr VA, Manna A, Restifo NP, Samelson LE. The Cish SH2 domain is essential for PLC-γ1 regulation in TCR stimulated CD8 + T cells. Sci Rep 2018; 8:5336. [PMID: 29593227 PMCID: PMC5871872 DOI: 10.1038/s41598-018-23549-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 03/06/2018] [Indexed: 12/22/2022] Open
Abstract
Cish, participates within a multi-molecular E3 ubiquitin ligase complex, which ubiquitinates target proteins. It has an inhibitory effect on T cell activation mediated by PLC-γ1 regulation, and it functions as a potent checkpoint in CD8+ T cell tumor immunotherapy. To study the structural and functional relationships between Cish and PLC-γ1 during CD8+ T cell activation, we tested mutants of the Cish-SH2 (R107K) and D/BC (L222Q, C226Q) domains. We confirmed that Cish-SH2-specific binding was essential for PLC-γ1 ubiquitination and degradation. This domain was essential for the Cish-mediated inhibition of Ca2+ release upon TCR stimulation. No effect on inhibition of cytokine release was observed with SH2 or D/BC mutants, although the absence of Cish led to an increased release of IFN-γ and TNF-α. Using imaging we showed that Cish was expressed mostly in the cytoplasm and we did not see any Cish clustering at the plasma membrane upon stimulation. We conclude that the Cish-SH2 domain is essential for PLC-γ1 regulation in TCR-stimulated CD8+ T cells.
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Affiliation(s)
- Geoffrey Guittard
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, 20892-4256, USA. .,INSERM, U1068, CNRS UMR7258, Aix-Marseille Université UM105, Institut Paoli-Calmettes, Centre de Recherche en Cancérologie de Marseille, 13009, Marseille, France.
| | - Ana Dios-Esponera
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, 20892-4256, USA
| | - Douglas C Palmer
- Surgery Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Building 10/CRC, Room 3W-3840, Bethesda, MD, 20892, USA
| | - Itoro Akpan
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, 20892-4256, USA
| | - Valarie A Barr
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, 20892-4256, USA
| | - Asit Manna
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, 20892-4256, USA
| | - Nicholas P Restifo
- Surgery Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Building 10/CRC, Room 3W-3840, Bethesda, MD, 20892, USA
| | - Lawrence E Samelson
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, 20892-4256, USA.
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Dios-Esponera A, Isern de Val S, Sevilla-Movilla S, García-Verdugo R, García-Bernal D, Arellano-Sánchez N, Cabañas C, Teixidó J. Positive and negative regulation by SLP-76/ADAP and Pyk2 of chemokine-stimulated T-lymphocyte adhesion mediated by integrin α4β1. Mol Biol Cell 2015. [PMID: 26202465 PMCID: PMC4569313 DOI: 10.1091/mbc.e14-07-1246] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Stimulation by chemokines of integrin α4β1-dependent T-lymphocyte adhesion is a crucial step for lymphocyte trafficking. The adaptor Vav1 is required for chemokine-activated T-cell adhesion mediated by α4β1. Conceivably, proteins associating with Vav1 could potentially modulate this adhesion. Correlating with activation by the chemokine CXCL12 of T-lymphocyte attachment to α4β1 ligands, a transient stimulation in the association of Vav1 with SLP-76, Pyk2, and ADAP was observed. Using T-cells depleted for SLP-76, ADAP, or Pyk2, or expressing Pyk2 kinase-inactive forms, we show that SLP-76 and ADAP stimulate chemokine-activated, α4β1-mediated adhesion, whereas Pyk2 opposes T-cell attachment. While CXCL12-promoted generation of high-affinity α4β1 is independent of SLP-76, ADAP, and Pyk2, the strength of α4β1-VCAM-1 interaction and cell spreading on VCAM-1 are targets of regulation by these three proteins. GTPase assays, expression of activated or dominant-negative Rac1, or combined ADAP and Pyk2 silencing indicated that Rac1 activation by CXCL12 is a common mediator response in SLP-76-, ADAP-, and Pyk2-regulated cell adhesion involving α4β1. Our data strongly suggest that chemokine-stimulated associations between Vav1, SLP-76, and ADAP facilitate Rac1 activation and α4β1-mediated adhesion, whereas Pyk2 opposes this adhesion by limiting Rac1 activation.
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Affiliation(s)
- Ana Dios-Esponera
- Centro de Investigaciones Biológicas (CSIC), Department of Cellular and Molecular Medicine, 28040 Madrid, Spain
| | - Soledad Isern de Val
- Centro de Investigaciones Biológicas (CSIC), Department of Cellular and Molecular Medicine, 28040 Madrid, Spain
| | - Silvia Sevilla-Movilla
- Centro de Investigaciones Biológicas (CSIC), Department of Cellular and Molecular Medicine, 28040 Madrid, Spain
| | - Rosa García-Verdugo
- Centro de Investigaciones Biológicas (CSIC), Department of Cellular and Molecular Medicine, 28040 Madrid, Spain
| | - David García-Bernal
- Centro de Investigaciones Biológicas (CSIC), Department of Cellular and Molecular Medicine, 28040 Madrid, Spain
| | - Nohemí Arellano-Sánchez
- Centro de Investigaciones Biológicas (CSIC), Department of Cellular and Molecular Medicine, 28040 Madrid, Spain
| | - Carlos Cabañas
- Centro de Biología Molecular (CSIC), Department of Cell Biology and Immunology, Cantoblanco, 28049 Madrid, Spain
| | - Joaquin Teixidó
- Centro de Investigaciones Biológicas (CSIC), Department of Cellular and Molecular Medicine, 28040 Madrid, Spain
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García-Bernal D, Redondo-Muñoz J, Dios-Esponera A, Chèvre R, Bailón E, Garayoa M, Arellano-Sánchez N, Gutierrez NC, Hidalgo A, García-Pardo A, Teixidó J. Sphingosine-1-phosphate activates chemokine-promoted myeloma cell adhesion and migration involving α4β1 integrin function. J Pathol 2013; 229:36-48. [PMID: 22711564 DOI: 10.1002/path.4066] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 05/14/2012] [Accepted: 06/12/2012] [Indexed: 12/21/2022]
Abstract
Myeloma cell adhesion dependent on α4β1 integrin is crucial for the progression of multiple myeloma (MM). The α4β1-dependent myeloma cell adhesion is up-regulated by the chemokine CXCL12, and pharmacological blockade of the CXCL12 receptor CXCR4 leads to defective myeloma cell homing to bone marrow (BM). Sphingosine-1-phosphate (S1P) regulates immune cell trafficking upon binding to G-protein-coupled receptors. Here we show that myeloma cells express S1P1, a receptor for S1P. We found that S1P up-regulated the α4β1-mediated myeloma cell adhesion and transendothelial migration stimulated by CXCL12. S1P promoted generation of high-affinity α4β1 that efficiently bound the α4β1 ligand VCAM-1, a finding that was associated with S1P-triggered increase in talin-β1 integrin association. Furthermore, S1P cooperated with CXCL12 for enhancement of α4β1-dependent adhesion strengthening and spreading. CXCL12 and S1P activated the DOCK2-Rac1 pathway, which was required for stimulation of myeloma cell adhesion involving α4β1. Moreover, in vivo analyses indicated that S1P contributes to optimizing the interactions of MM cells with the BM microvasculture and for their lodging inside the bone marrow. The regulation of α4β1-dependent adhesion and migration of myeloma cells by CXCL12-S1P combined activities might have important consequences for myeloma disease progression.
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Affiliation(s)
- David García-Bernal
- Cellular and Molecular Medicine Programme, Centro de Investigaciones Biológicas, Madrid, Spain
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García-Bernal D, Dios-Esponera A, Sotillo-Mallo E, García-Verdugo R, Arellano-Sánchez N, Teixidó J. RGS10 restricts upregulation by chemokines of T cell adhesion mediated by α4β1 and αLβ2 integrins. J Immunol 2011; 187:1264-72. [PMID: 21705617 DOI: 10.4049/jimmunol.1002960] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Chemokines rapidly and transiently upregulate α4β1 and αLβ2 integrin-mediated adhesion during T lymphocyte extravasation by activating Gα-dependent inside-out signaling. To limit and terminate Gα-mediated signaling, cells can use several mechanisms, including the action of regulator of G protein signaling (RGS) proteins, which accelerate the GTPase activity of Gα subunits. Using human T cells silenced for or overexpressing RGS10, we show in this article that RGS10 functions as an inhibitor of Gα(i)-dependent, chemokine-upregulated T cell adhesion mediated by α4β1 and αLβ2. Shear stress-dependent detachment and cell spreading analyses revealed that RGS10 action mainly targets the adhesion strengthening and spreading phases of α4β1-mediated cell attachment. Associated with these observations, chemokine-stimulated Vav1-Rac1 activation was longer sustained and of higher intensity in RGS10-silenced T cells, or inhibited in cells overexpressing RGS10. Of importance, expression of constitutively activated Rac1 forms in cells overexpressing RGS10 led to the rescue of CXCL12-stimulated adhesion to VCAM-1 to levels similar to those in control transfectants. Instead, adhesion under flow conditions, soluble binding experiment, flow cytometry, and biochemical analyses revealed that the earlier chemokine-triggered integrin activation step was mostly independent of RGS10 actions. The data strongly suggest that RGS10 opposes activation by chemokines of the Vav1-Rac1 pathway in T cells, leading to repression of adhesion strengthening mediated by α4β1. In addition to control chemokine-upregulated T cell attachment, RGS10 also limited adhesion-independent cell chemotaxis and activation of cdc42. These results identify RGS10 as a key molecule that contributes to the termination of Gα-dependent signaling during chemokine-activated α4β1- and αLβ2-dependent T cell adhesion.
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Affiliation(s)
- David García-Bernal
- Departamento de Medicina Celular y Molecular, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain
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García-Bernal D, Parmo-Cabañas M, Dios-Esponera A, Samaniego R, Hernán-P de la Ossa D, Teixidó J. Chemokine-induced Zap70 kinase-mediated dissociation of the Vav1-talin complex activates alpha4beta1 integrin for T cell adhesion. Immunity 2009; 31:953-64. [PMID: 20005136 DOI: 10.1016/j.immuni.2009.09.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 08/31/2009] [Accepted: 09/25/2009] [Indexed: 01/13/2023]
Abstract
Lymphocyte integrins mediate cell arrest on endothelium during immune surveillance after activation by chemokine-stimulated inside-out signals. Here we show that a Vav1-talin complex in T cells is a key target for chemokine-triggered inside-out signaling leading to integrin alpha4beta1 activation. Thus, Vav1 dissociation from talin was required to generate high-affinity alpha4beta1 conformations. Assembly of the Vav1-talin complex required PtdIns(4,5)P(2), which was provided by talin-bound phosphatidylinositol phosphate kinase Igamma. Chemokine-promoted Vav1 dissociation from talin followed an initial increase in talin binding to alpha4beta1. This process was dependent on ZAP-70, which binds to and phosphorylates Vav1 in the complex, leading to further alpha4beta1 activation and cell adhesion strengthening. Moreover, Vav1-talin dissociation was needed for Rac1 activation, thus indicating that alpha4beta1 and Rac1 activation can be coupled by chemokine-stimulated ZAP-70 function. Our data suggest that Vav1 might function as a repressive adaptor of talin that must dissociate from alpha4beta1-talin complexes for efficient integrin activation.
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Affiliation(s)
- David García-Bernal
- Cellular and Molecular Medicine Program, Centro de Investigaciones Biológicas (CSIC), 28040 Madrid, Spain
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