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Bermúdez V, Tenconi PE, Giusto NM, Mateos MV. Canonical phospholipase D isoforms in visual function and ocular response to stress. Exp Eye Res 2022; 217:108976. [DOI: 10.1016/j.exer.2022.108976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 01/09/2022] [Accepted: 02/01/2022] [Indexed: 01/10/2023]
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Casado-Medrano V, Barrio-Real L, Gutiérrez-Miranda L, González-Sarmiento R, Velasco EA, Kazanietz MG, Caloca MJ. Identification of a truncated β1-chimaerin variant that inactivates nuclear Rac1. J Biol Chem 2019; 295:1300-1314. [PMID: 31871052 DOI: 10.1074/jbc.ra119.008688] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 12/14/2019] [Indexed: 12/11/2022] Open
Abstract
β1-chimaerin belongs to the chimaerin family of GTPase-activating proteins (GAPs) and is encoded by the CHN2 gene, which also encodes the β2- and β3-chimaerin isoforms. All chimaerin isoforms have a C1 domain that binds diacylglycerol as well as tumor-promoting phorbol esters and a catalytic GAP domain that inactivates the small GTPase Rac. Nuclear Rac has emerged as a key regulator of various cell functions, including cell division, and has a pathological role by promoting tumorigenesis and metastasis. However, how nuclear Rac is regulated has not been fully addressed. Here, using several approaches, including siRNA-mediated gene silencing, confocal microscopy, and subcellular fractionation, we identified a nuclear variant of β1-chimaerin, β1-Δ7p-chimaerin, that participates in the regulation of nuclear Rac1. We show that β1-Δ7p-chimaerin is a truncated variant generated by alternative splicing at a cryptic splice site in exon 7. We found that, unlike other chimaerin isoforms, β1-Δ7p-chimaerin lacks a functional C1 domain and is not regulated by diacylglycerol. We found that β1-Δ7p-chimaerin localizes to the nucleus via a nuclear localization signal in its N terminus. We also identified a key nuclear export signal in β1-chimaerin that is absent in β1-Δ7p-chimaerin, causing nuclear retention of this truncated variant. Functionally analyses revealed that β1-Δ7p-chimaerin inactivates nuclear Rac and negatively regulates the cell cycle. Our results provide important insights into the diversity of chimaerin Rac-GAP regulation and function and highlight a potential mechanism of nuclear Rac inactivation that may play significant roles in pathologies such as cancer.
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Affiliation(s)
- Victoria Casado-Medrano
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
| | - Laura Barrio-Real
- Molecular Medicine Unit and Institute of Molecular and Cellular Biology of Cancer, Biomedical Research Institute of Salamanca, University of Salamanca, 37007 Salamanca, Spain
| | - Laura Gutiérrez-Miranda
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
| | - Rogelio González-Sarmiento
- Molecular Medicine Unit and Institute of Molecular and Cellular Biology of Cancer, Biomedical Research Institute of Salamanca, University of Salamanca, 37007 Salamanca, Spain
| | - Eladio A Velasco
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
| | - Marcelo G Kazanietz
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - María J Caloca
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
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Tenconi PE, Bermúdez V, Oresti GM, Giusto NM, Salvador GA, Mateos MV. High glucose-induced phospholipase D activity in retinal pigment epithelium cells: New insights into the molecular mechanisms of diabetic retinopathy. Exp Eye Res 2019; 184:243-257. [PMID: 31059692 DOI: 10.1016/j.exer.2019.04.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 04/05/2019] [Accepted: 04/30/2019] [Indexed: 02/02/2023]
Abstract
Chronic hyperglycemia, oxidative stress and inflammation are key players in the pathogenesis of diabetic retinopathy (DR). In this work we study the role of phospholipase D (PLD) pathway in an in vitro model of high glucose (HG)-induced damage. To this end, we exposed human retinal pigment epithelium (RPE) cell lines (ARPE-19 and D407) to HG concentrations (16.5 or 33 mM) or to normal glucose concentration (NG, 5.5 mM) for 4, 24 or 72 h. Exposure to HG increased reactive oxygen species levels and caspase-3 cleavage and reduced cell viability after 72 h of incubation. In addition, short term HG exposure (4 h) induced the activation of early events, that involve PLD and ERK1/2 signaling, nuclear factor kappa B (NFκB) nuclear translocation and IκB phosphorylation. The increment in pro-inflammatory interleukins (IL-6 and IL-8) and cyclooxygenase-2 (COX-2) mRNA levels was observed after 24 h of HG exposure. The effect of selective pharmacological PLD1 (VU0359595) and PLD2 (VU0285655-1) inhibitors demonstrated that ERK1/2 and NFκB activation were downstream events of both PLD isoforms. The increment in IL-6 and COX-2 mRNA levels induced by HG was reduced to control levels in cells pre-incubated with both PLD inhibitors. Furthermore, the inhibition of PLD1, PLD2 and MEK/ERK pathway prevented the loss of cell viability and the activation of caspase-3 induced by HG. In conclusion, our findings demonstrate that PLD1 and PLD2 mediate the inflammatory response triggered by HG in RPE cells, pointing to their potential use as a therapeutic target for DR treatment.
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Affiliation(s)
- Paula E Tenconi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000, Bahía, Blanca, Argentina; Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), 8000, Bahía, Blanca, Argentina
| | - Vicente Bermúdez
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000, Bahía, Blanca, Argentina
| | - Gerardo M Oresti
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000, Bahía, Blanca, Argentina; Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), 8000, Bahía, Blanca, Argentina
| | - Norma M Giusto
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000, Bahía, Blanca, Argentina; Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), 8000, Bahía, Blanca, Argentina
| | - Gabriela A Salvador
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000, Bahía, Blanca, Argentina; Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), 8000, Bahía, Blanca, Argentina
| | - Melina V Mateos
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000, Bahía, Blanca, Argentina; Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), 8000, Bahía, Blanca, Argentina.
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Broadgate S, Kiire C, Halford S, Chong V. Diabetic macular oedema: under-represented in the genetic analysis of diabetic retinopathy. Acta Ophthalmol 2018; 96 Suppl A111:1-51. [PMID: 29682912 DOI: 10.1111/aos.13678] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 11/21/2017] [Indexed: 12/15/2022]
Abstract
Diabetic retinopathy, a complication of both type 1 and type 2 diabetes, is a complex disease and is one of the leading causes of blindness in adults worldwide. It can be divided into distinct subclasses, one of which is diabetic macular oedema. Diabetic macular oedema can occur at any time in diabetic retinopathy and is the most common cause of vision loss in patients with type 2 diabetes. The purpose of this review is to summarize the large number of genetic association studies that have been performed in cohorts of patients with type 2 diabetes and published in English-language journals up to February 2017. Many of these studies have produced positive associations with gene polymorphisms and diabetic retinopathy. However, this review highlights that within this large body of work, studies specifically addressing a genetic association with diabetic macular oedema, although present, are vastly under-represented. We also highlight that many of the studies have small patient numbers and that meta-analyses often inappropriately combine patient data sets. We conclude that there will continue to be conflicting results and no meaningful findings will be achieved if the historical approach of combining all diabetic retinopathy disease states within patient cohorts continues in future studies. This review also identifies several genes that would be interesting to analyse in large, well-defined cohorts of patients with diabetic macular oedema in future candidate gene association studies.
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Affiliation(s)
- Suzanne Broadgate
- Nuffield Laboratory of Ophthalmology; Nuffield Department of Clinical Neurosciences; University of Oxford; Oxford UK
| | - Christine Kiire
- Nuffield Laboratory of Ophthalmology; Nuffield Department of Clinical Neurosciences; University of Oxford; Oxford UK
- Oxford Eye Hospital; John Radcliffe Hospital; Oxford University NHS Foundation Trust; Oxford UK
| | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology; Nuffield Department of Clinical Neurosciences; University of Oxford; Oxford UK
| | - Victor Chong
- Nuffield Laboratory of Ophthalmology; Nuffield Department of Clinical Neurosciences; University of Oxford; Oxford UK
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A new role of the Rac-GAP β2-chimaerin in cell adhesion reveals opposite functions in breast cancer initiation and tumor progression. Oncotarget 2017; 7:28301-19. [PMID: 27058424 PMCID: PMC5053728 DOI: 10.18632/oncotarget.8597] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 03/27/2016] [Indexed: 01/06/2023] Open
Abstract
β2-chimaerin is a Rac1-specific negative regulator and a candidate tumor suppressor in breast cancer but its precise function in mammary tumorigenesis in vivo is unknown. Here, we study for the first time the role of β2-chimaerin in breast cancer using a mouse model and describe an unforeseen role for this protein in epithelial cell-cell adhesion. We demonstrate that expression of β2-chimaerin in breast cancer epithelial cells reduces E-cadherin protein levels, thus loosening cell-cell contacts. In vivo, genetic ablation of β2-chimaerin in the MMTV-Neu/ErbB2 mice accelerates tumor onset, but delays tumor progression. Finally, analysis of clinical databases revealed an inverse correlation between β2-chimaerin and E-cadherin gene expressions in Her2+ breast tumors. Furthermore, breast cancer patients with low β2-chimaerin expression have reduced relapse free survival but develop metastasis at similar times. Overall, our data redefine the role of β2-chimaerin as tumor suppressor and provide the first in vivo evidence of a dual function in breast cancer, suppressing tumor initiation but favoring tumor progression.
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Tenconi PE, Giusto NM, Salvador GA, Mateos MV. Phospholipase D1 modulates protein kinase C-epsilon in retinal pigment epithelium cells during inflammatory response. Int J Biochem Cell Biol 2016; 81:67-75. [DOI: 10.1016/j.biocel.2016.10.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 10/11/2016] [Accepted: 10/19/2016] [Indexed: 12/13/2022]
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Chen SS, Hu Z, Zhong XP. Diacylglycerol Kinases in T Cell Tolerance and Effector Function. Front Cell Dev Biol 2016; 4:130. [PMID: 27891502 PMCID: PMC5103287 DOI: 10.3389/fcell.2016.00130] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/27/2016] [Indexed: 12/21/2022] Open
Abstract
Diacylglycerol kinases (DGKs) are a family of enzymes that regulate the relative levels of diacylglycerol (DAG) and phosphatidic acid (PA) in cells by phosphorylating DAG to produce PA. Both DAG and PA are important second messengers cascading T cell receptor (TCR) signal by recruiting multiple effector molecules, such as RasGRP1, PKCθ, and mTOR. Studies have revealed important physiological functions of DGKs in the regulation of receptor signaling and the development and activation of immune cells. In this review, we will focus on recent progresses in our understanding of two DGK isoforms, α and ζ, in CD8 T effector and memory cell differentiation, regulatory T cell development and function, and invariant NKT cell development and effector lineage differentiation.
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Affiliation(s)
- Shelley S Chen
- Division of Allergy and Immunology, Department of Pediatrics, Duke University Medical Center Durham, NC, USA
| | - Zhiming Hu
- Division of Allergy and Immunology, Department of Pediatrics, Duke University Medical CenterDurham, NC, USA; Institute of Biotherapy, School of Biotechnology, Southern Medical UniversityGuangzhou, China
| | - Xiao-Ping Zhong
- Division of Allergy and Immunology, Department of Pediatrics, Duke University Medical CenterDurham, NC, USA; Department of Immunology, Duke University Medical CenterDurham, NC, USA; Hematologic Malignancies and Cellular Therapies Program, Duke Cancer Institute, Duke University Medical CenterDurham, NC, USA
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Integrative genomic and transcriptomic analysis identified candidate genes implicated in the pathogenesis of hepatosplenic T-cell lymphoma. PLoS One 2014; 9:e102977. [PMID: 25057852 PMCID: PMC4109958 DOI: 10.1371/journal.pone.0102977] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 06/23/2014] [Indexed: 12/20/2022] Open
Abstract
Hepatosplenic T-cell lymphoma (HSTL) is an aggressive lymphoma cytogenetically characterized by isochromosome 7q [i(7)(q10)], of which the molecular consequences remain unknown. We report here results of an integrative genomic and transcriptomic (expression microarray and RNA-sequencing) study of six i(7)(q10)-positive HSTL cases, including HSTL-derived cell line (DERL-2), and three cases with ring 7 [r(7)], the recently identified rare variant aberration. Using high resolution array CGH, we profiled all cases and mapped the common deleted region (CDR) at 7p22.1p14.1 (34.88 Mb; 3506316-38406226 bp) and the common gained region (CGR) at 7q22.11q31.1 (38.77 Mb; 86259620–124892276 bp). Interestingly, CDR spans a smaller region of 13 Mb (86259620–99271246 bp) constantly amplified in cases with r(7). In addition, we found that TCRG (7p14.1) and TCRB (7q32) are involved in formation of r(7), which seems to be a byproduct of illegitimate somatic rearrangement of both loci. Further transcriptomic analysis has not identified any CDR-related candidate tumor suppressor gene. Instead, loss of 7p22.1p14.1 correlated with an enhanced expression of CHN2 (7p14.1) and the encoded β2-chimerin. Gain and amplification of 7q22.11q31.1 are associated with an increased expression of several genes postulated to be implicated in cancer, including RUNDC3B, PPP1R9A and ABCB1, a known multidrug resistance gene. RNA-sequencing did not identify any disease-defining mutation or gene fusion. Thus, chromosome 7 imbalances remain the only driver events detected in this tumor. We hypothesize that the Δ7p22.1p14.1-associated enhanced expression of CHN2/β2-chimerin leads to downmodulation of the NFAT pathway and a proliferative response, while upregulation of the CGR-related genes provides growth advantage for neoplastic δγT-cells and underlies their intrinsic chemoresistance. Finally, our study confirms the previously described gene expression profile of HSTL and identifies a set of 24 genes, including three located on chromosome 7 (CHN2, ABCB1 and PPP1R9A), distinguishing HSTL from other malignancies.
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Chen M, Lin WR, Lu CH, Chen CC, Huang YC, Liao WL, Tsai FJ. Chimerin 2 genetic polymorphisms are associated with non-proliferative diabetic retinopathy in Taiwanese type 2 diabetic patients. J Diabetes Complications 2014; 28:460-3. [PMID: 24854763 DOI: 10.1016/j.jdiacomp.2014.04.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 04/01/2014] [Accepted: 04/11/2014] [Indexed: 12/12/2022]
Abstract
AIM To investigate whether chimerin 2 (CHN2) genetic polymorphisms were associated with the susceptibility to diabetic retinopathy (DR) in Taiwanese individuals with type 2 diabetes. METHODS This case-control study comprised of 171 individuals with DR and 548 without DR. Four rs39059, rs2023908, rs1002630 and rs1362363 polymorphism of CHN2 were genotyped for each subjects. All subjects underwent a complete ophthalmologic examination, and basic information (age, gender, age at diagnosis of diabetes, and ocular history of the patient) was record. Several clinical parameters (systolic and diastolic blood pressure, waist and hip circumferences, body mass index levels, fasting glucose and HbA1c) were measured. RESULTS Logistic regressions were used to analyze odds ratios between SNPs and DR after controlling for gender, systolic blood pressure, waist and hip ratio, duration of diabetes, serum HbA1c levels and nephropathy classification. A protective effect of rs1002630 (GA+AA) and rs1362363 (AG+GG) [odds ratio (OR) (95% confidence interval)=0.45 (0.22-0.88), 0.66 (0.44-0.99), respectively) was observed. Furthermore, the protective effect of rs1002630 was observed when compared subjects with non-proliferative DR with subjects without DR [OR=0.25 (95%C.I. = 0.09-0.73)]. CONCLUSIONS This study showed that the rs1002630 of CHN2 were associated with DR risk and non-proliferative DR risk in Taiwanese individuals with type 2 diabetes. Variations at this locus may contribute to the pathogenesis of DR.
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Affiliation(s)
- Marcelo Chen
- Department of Urology, Mackay Memorial Hospital, Taipei, Taiwan; Mackay Medicine, Nursing and Management College, Taipei, Taiwan; School of Medicine, Mackay Medical College, New Taipei City, Taiwan
| | - Wun-Rong Lin
- Department of Urology, Mackay Memorial Hospital, Taipei, Taiwan
| | - Chieh-Hsiang Lu
- Division of Endocrinology and Metabolism of Internal Medicine, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chia-Yi, Taiwan
| | - Ching-Chu Chen
- Division of Endocrinology and Metabolism, Department of Medicine, China Medical University Hospital, Taichung, Taiwan; School of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Yu-Chuen Huang
- School of Chinese Medicine, China Medical University, Taichung, Taiwan; Genetics Center, Department of Medical Research, China Medical University Hospital, Taichung, Taiwan
| | - Wen-Ling Liao
- Center for Personalized Medicine, China Medical University Hospital, Taichung, Taiwan; Graduate Institute of Integrate Medicine, School of Chinese Medicine, China Medical University, Taichung, Taiwan.
| | - Fuu-Jen Tsai
- School of Chinese Medicine, China Medical University, Taichung, Taiwan; Genetics Center, Department of Medical Research, China Medical University Hospital, Taichung, Taiwan.
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Gutierrez-Uzquiza A, Colon-Gonzalez F, Leonard TA, Canagarajah BJ, Wang H, Mayer BJ, Hurley JH, Kazanietz MG. Coordinated activation of the Rac-GAP β2-chimaerin by an atypical proline-rich domain and diacylglycerol. Nat Commun 2013; 4:1849. [PMID: 23673634 PMCID: PMC3700536 DOI: 10.1038/ncomms2834] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 04/04/2013] [Indexed: 02/08/2023] Open
Abstract
Chimaerins, a family of GTPase activating proteins (GAPs) for the small G-protein Rac, have been implicated in development, neuritogenesis, and cancer. These Rac-GAPs are regulated by the lipid second messenger diacylglycerol (DAG) generated by tyrosine-kinases such as the epidermal growth factor receptor (EGFR). Here we identify an atypical Pro-rich motif in chimaerins that binds to the adaptor protein Nck1. Unlike most Nck1 partners, chimaerins bind to the third SH3 domain of Nck1. This association is mediated by electrostatic interactions of basic residues within the Pro-rich motif with acidic clusters in the SH3 domain. EGF promotes the binding of β2-chimaerin to Nck1 in the cell periphery in a DAG-dependent manner. Moreover, β2-chimaerin translocation to the plasma membrane and its peripheral association with Rac1 requires Nck1. Our studies underscore a coordinated mechanism for β2-chimaerin activation that involves lipid interactions via the C1 domain and protein-protein interactions via the N-terminal Pro-rich region.
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Affiliation(s)
- Alvaro Gutierrez-Uzquiza
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6160, USA
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Jun JE, Rubio I, Roose JP. Regulation of ras exchange factors and cellular localization of ras activation by lipid messengers in T cells. Front Immunol 2013; 4:239. [PMID: 24027568 PMCID: PMC3762125 DOI: 10.3389/fimmu.2013.00239] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 08/02/2013] [Indexed: 11/17/2022] Open
Abstract
The Ras-MAPK signaling pathway is highly conserved throughout evolution and is activated downstream of a wide range of receptor stimuli. Ras guanine nucleotide exchange factors (RasGEFs) catalyze GTP loading of Ras and play a pivotal role in regulating receptor-ligand induced Ras activity. In T cells, three families of functionally important RasGEFs are expressed: RasGRF, RasGRP, and Son of Sevenless (SOS)-family GEFs. Early on it was recognized that Ras activation is critical for T cell development and that the RasGEFs play an important role herein. More recent work has revealed that nuances in Ras activation appear to significantly impact T cell development and selection. These nuances include distinct biochemical patterns of analog versus digital Ras activation, differences in cellular localization of Ras activation, and intricate interplays between the RasGEFs during distinct T cell developmental stages as revealed by various new mouse models. In many instances, the exact nature of these nuances in Ras activation or how these may result from fine-tuning of the RasGEFs is not understood. One large group of biomolecules critically involved in the control of RasGEFs functions are lipid second messengers. Multiple, yet distinct lipid products are generated following T cell receptor (TCR) stimulation and bind to different domains in the RasGRP and SOS RasGEFs to facilitate the activation of the membrane-anchored Ras GTPases. In this review we highlight how different lipid-based elements are generated by various enzymes downstream of the TCR and other receptors and how these dynamic and interrelated lipid products may fine-tune Ras activation by RasGEFs in developing T cells.
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Affiliation(s)
- Jesse E Jun
- Department of Anatomy, University of California San Francisco , San Francisco, CA , USA
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Krishna S, Zhong XP. Regulation of Lipid Signaling by Diacylglycerol Kinases during T Cell Development and Function. Front Immunol 2013; 4:178. [PMID: 23847619 PMCID: PMC3701226 DOI: 10.3389/fimmu.2013.00178] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 06/19/2013] [Indexed: 01/14/2023] Open
Abstract
Diacylglycerol (DAG) and phosphatidic acid (PA) are bioactive lipids synthesized when the T cell receptor binds to a cognate peptide-MHC complex. DAG triggers signaling by recruiting Ras guanyl-releasing protein 1, PKCθ, and other effectors, whereas PA binds to effector molecules that include mechanistic target of rapamycin, Src homology region 2 domain-containing phosphatase 1, and Raf1. While DAG-mediated pathways have been shown to play vital roles in T cell development and function, the importance of PA-mediated signals remains less clear. The diacylglycerol kinase (DGK) family of enzymes phosphorylates DAG to produce PA, serving as a molecular switch that regulates the relative levels of these critical second messengers. Two DGK isoforms, α and ζ, are predominantly expressed in T lineage cells and play an important role in conventional αβ T cell development. In mature T cells, the activity of these DGK isoforms aids in the maintenance of self-tolerance by preventing T cell hyper-activation and promoting T cell anergy. In this review, we discuss the roles of DAG-mediated pathways, PA-effectors, and DGKs in T cell development and function. We also highlight recent work that has uncovered previously unappreciated roles for DGK activity, for instance in invariant NKT cell development, anti-tumor and anti-viral CD8 responses, and the directional secretion of soluble effectors.
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Affiliation(s)
- Sruti Krishna
- Department of Pediatrics, Division of Allergy and Immunology, Duke University Medical Center , Durham, NC , USA ; Department of Immunology, Duke University Medical Center , Durham, NC , USA
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Arrizabalaga O, Lacerda HM, Zubiaga AM, Zugaza JL. Rac1 protein regulates glycogen phosphorylase activation and controls interleukin (IL)-2-dependent T cell proliferation. J Biol Chem 2012; 287:11878-90. [PMID: 22337875 DOI: 10.1074/jbc.m111.297804] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Small GTPases of the Rho family have been implicated in important cellular processes such as cell migration and adhesion, protein secretion, and/or gene transcription. In the lymphoid system, these GTPases participate in the signaling cascades that are activated after engagement of antigen receptors. However, little is known about the role that Rho GTPases play in IL-2-mediated responses. Here, we show that IL-2 induces Rac1 activation in Kit 225 T cells. We identified by mass spectrometry the muscle isoform of glycogen phosphorylase (PYGM) as a novel Rac1 effector molecule in IL-2-stimulated cells. The interaction between the active form of Rac1 (Rac1-GTP) and PYGM was established directly through a domain comprising amino acids 191-270 of PYGM that exhibits significant homology with the Rac binding domain of PAK1. The integrity of this region was crucial for PYGM activation. Importantly, IL-2-dependent cellular proliferation was inhibited upon blocking both the activation of Rac1 and the activity of PYGM. These results reveal a new role for Rac1 in cell signaling, showing that this GTPase triggers T cell proliferation upon IL-2 stimulation by associating with PYGM and modulating its enzymatic activity.
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Affiliation(s)
- Onetsine Arrizabalaga
- Department of Genetics, Physical Anthropology and Animal Physiology, University of the Basque Country, 48940 Leioa, Spain
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Ligeti E, Welti S, Scheffzek K. Inhibition and Termination of Physiological Responses by GTPase Activating Proteins. Physiol Rev 2012; 92:237-72. [DOI: 10.1152/physrev.00045.2010] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Physiological processes are strictly organized in space and time. However, in cell physiology research, more attention is given to the question of space rather than to time. To function as a signal, environmental changes must be restricted in time; they need not only be initiated but also terminated. In this review, we concentrate on the role of one specific protein family involved in biological signal termination. GTPase activating proteins (GAPs) accelerate the endogenously low GTP hydrolysis rate of monomeric guanine nucleotide-binding proteins (GNBPs), limiting thereby their prevalence in the active, GTP-bound form. We discuss cases where defective or excessive GAP activity of specific proteins causes significant alteration in the function of the nervous, endocrine, and hemopoietic systems, or contributes to development of infections and tumors. Biochemical and genetic data as well as observations from human pathology support the notion that GAPs represent vital elements in the spatiotemporal fine tuning of physiological processes.
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Affiliation(s)
- Erzsébet Ligeti
- Department of Physiology, Semmelweis University, Budapest, Hungary; Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany; and Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | - Stefan Welti
- Department of Physiology, Semmelweis University, Budapest, Hungary; Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany; and Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | - Klaus Scheffzek
- Department of Physiology, Semmelweis University, Budapest, Hungary; Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany; and Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Innsbruck, Austria
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16
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Abstract
Second messenger molecules relay, amplify, and diversify cell surface receptor signals. Two important examples are phosphorylated D-myo-inositol derivatives, such as phosphoinositide lipids within cellular membranes, and soluble inositol phosphates. Here, we review how phosphoinositide metabolism generates multiple second messengers with important roles in T-cell development and function. They include soluble inositol(1,4,5)trisphosphate, long known for its Ca(2+)-mobilizing function, and phosphatidylinositol(3,4,5)trisphosphate, whose generation by phosphoinositide 3-kinase and turnover by the phosphatases PTEN and SHIP control a key "hub" of TCR signaling. More recent studies unveiled important second messenger functions for diacylglycerol, phosphatidic acid, and soluble inositol(1,3,4,5)tetrakisphosphate (IP(4)) in immune cells. Inositol(1,3,4,5)tetrakisphosphate acts as a soluble phosphatidylinositol(3,4,5)trisphosphate analog to control protein membrane recruitment. We propose that phosphoinositide lipids and soluble inositol phosphates (IPs) can act as complementary partners whose interplay could have broadly important roles in cellular signaling.
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Affiliation(s)
- Yina H Huang
- Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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17
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Suliman SG, Stanik J, McCulloch LJ, Wilson N, Edghill EL, Misovicova N, Gasperikova D, Sandrikova V, Elliott KS, Barak L, Ellard S, Volpi EV, Klimes I, Gloyn AL. Severe insulin resistance and intrauterine growth deficiency associated with haploinsufficiency for INSR and CHN2: new insights into synergistic pathways involved in growth and metabolism. Diabetes 2009; 58:2954-61. [PMID: 19720790 PMCID: PMC2780873 DOI: 10.2337/db09-0787] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Digenic causes of human disease are rarely reported. Insulin via its receptor, which is encoded by INSR, plays a key role in both metabolic and growth signaling pathways. Heterozygous INSR mutations are the most common cause of monogenic insulin resistance. However, growth retardation is only reported with homozygous or compound heterozygous mutations. We describe a novel translocation [t(7,19)(p15.2;p13.2)] cosegregating with insulin resistance and pre- and postnatal growth deficiency. Chromosome translocations present a unique opportunity to identify modifying loci; therefore, our objective was to determine the mutational mechanism resulting in this complex phenotype. RESEARCH DESIGN AND METHODS Breakpoint mapping was performed by fluorescence in situ hybridization (FISH) on patient chromosomes. Sequencing and gene expression studies of disrupted and adjacent genes were performed on patient-derived tissues. RESULTS Affected individuals had increased insulin, C-peptide, insulin-to-C-peptide ratio, and adiponectin levels consistent with an insulin receptoropathy. FISH mapping established that the translocation breakpoints disrupt INSR on chromosome 19p15.2 and CHN2 on chromosome 7p13.2. Sequencing demonstrated INSR haploinsufficiency accounting for elevated insulin levels and dysglycemia. CHN2 encoding beta-2 chimerin was shown to be expressed in insulin-sensitive tissues, and its disruption was shown to result in decreased gene expression in patient-derived adipose tissue. CONCLUSIONS We present a likely digenic cause of insulin resistance and growth deficiency resulting from the combined heterozygous disruption of INSR and CHN2, implicating CHN2 for the first time as a key element of proximal insulin signaling in vivo.
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MESH Headings
- Adult
- Age of Onset
- Antigens, CD/genetics
- Biomarkers/blood
- Blood Glucose/metabolism
- C-Peptide/blood
- Chromosome Mapping
- Chromosomes, Human, Pair 19
- Chromosomes, Human, Pair 7
- DNA-Binding Proteins/genetics
- Diabetes Mellitus/genetics
- Diabetes Mellitus/metabolism
- Female
- Fetal Growth Retardation/genetics
- Fetal Growth Retardation/metabolism
- Gene Expression Regulation
- Growth Disorders/genetics
- Growth Disorders/metabolism
- Haplotypes
- Humans
- In Situ Hybridization, Fluorescence
- Insulin/blood
- Insulin/metabolism
- Insulin Resistance
- Male
- Pregnancy
- Receptor, Insulin/genetics
- Receptors, Steroid/genetics
- Receptors, Thyroid Hormone/genetics
- Sequence Analysis, DNA
- Signal Transduction
- Translocation, Genetic
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Affiliation(s)
- Sara G.I. Suliman
- Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, Oxford, U.K
| | - Juraj Stanik
- DIABGENE and Diabetes Laboratory, Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic
- Children Diabetes Centre at 1st Paediatric Department, Comenius University School of Medicine, Bratislava, Slovak Republic
| | - Laura J. McCulloch
- Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, Oxford, U.K
| | - Natalie Wilson
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, U.K
| | - Emma L. Edghill
- Institute of Biomedical and Clinical Sciences, Peninsula Medical School, Exeter, U.K
| | - Nadezda Misovicova
- Clinical Genetics, Jessenius School of Medicine, Martin, Slovak Republic
| | - Daniela Gasperikova
- DIABGENE and Diabetes Laboratory, Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Vilja Sandrikova
- Paediatric Endocrinology Outpatient Clinic, Prievidza Hospital, Prievidza, Slovak Republic
| | | | - Lubomir Barak
- Children Diabetes Centre at 1st Paediatric Department, Comenius University School of Medicine, Bratislava, Slovak Republic
| | - Sian Ellard
- Institute of Biomedical and Clinical Sciences, Peninsula Medical School, Exeter, U.K
- Department of Molecular Genetics, Royal Devon & Exeter National Health Service Trust, Exeter, U.K
| | - Emanuela V. Volpi
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, U.K
| | - Iwar Klimes
- DIABGENE and Diabetes Laboratory, Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Anna L. Gloyn
- Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, Oxford, U.K
- Corresponding author: Anna L. Gloyn,
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18
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Sosa MS, Lewin NE, Choi SH, Blumberg PM, Kazanietz MG. Biochemical characterization of hyperactive beta2-chimaerin mutants revealed an enhanced exposure of C1 and Rac-GAP domains. Biochemistry 2009; 48:8171-8. [PMID: 19618918 DOI: 10.1021/bi9010623] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent studies established that the Rac-GAP beta2-chimaerin plays important roles in development, neuritogenesis, and cancer progression. A unique feature of beta2-chimaerin is that it can be activated by phorbol esters and the lipid second messenger diacylglycerol (DAG), which bind with high affinity to its C1 domain and promote beta2-chimaerin translocation to membranes, leading to the inactivation of the small G-protein Rac. Crystallographic evidence and cellular studies suggest that beta2-chimaerin remains in an inactive conformation in the cytosol with the C1 domain inaccessible to ligands. We developed a series of beta2-chimaerin point mutants in which intramolecular contacts that occlude the C1 domain have been disrupted. These mutants showed enhanced translocation in response to phorbol 12-myristate 13-acetate (PMA) in cells. Binding assays using [(3)H]phorbol 12,13-dibutyrate ([(3)H]PDBu) revealed that internal contact mutants have a reduced acidic phospholipid requirement for phorbol ester binding. Moreover, disruption of intramolecular contacts enhances binding of beta2-chimaerin to acidic phospholipid vesicles and confers enhanced Rac-GAP activity in vitro. These studies suggest that beta2-chimaerin must undergo a conformational rearrangement in order to expose its lipid binding sites and become activated.
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Affiliation(s)
- Maria Soledad Sosa
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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19
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Localized diacylglycerol drives the polarization of the microtubule-organizing center in T cells. Nat Immunol 2009; 10:627-35. [PMID: 19430478 DOI: 10.1038/ni.1734] [Citation(s) in RCA: 185] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Accepted: 04/09/2009] [Indexed: 12/16/2022]
Abstract
The reorientation of the T cell microtubule-organizing center (MTOC) toward the antigen-presenting cell enables the directional secretion of cytokines and lytic factors. By single-cell photoactivation of the T cell antigen receptor, we show that MTOC polarization is driven by localized accumulation of diacylglycerol (DAG). MTOC reorientation was closely preceded first by production of DAG and then by recruitment of the microtubule motor protein dynein. Blocking DAG production or disrupting the localization of DAG impaired MTOC recruitment. Localized DAG accumulation was also required for cytotoxic T cell-mediated killing. Furthermore, photoactivation of DAG itself was sufficient to induce transient polarization. Our data identify a DAG-dependent pathway that signals through dynein to control microtubule polarity in T cells.
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20
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Takeuchi S, Yamaki N, Iwasato T, Negishi M, Katoh H. Beta2-chimaerin binds to EphA receptors and regulates cell migration. FEBS Lett 2009; 583:1237-42. [PMID: 19306875 DOI: 10.1016/j.febslet.2009.03.032] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 03/13/2009] [Accepted: 03/16/2009] [Indexed: 11/16/2022]
Abstract
Ephrins and Eph receptors have key roles in regulation of cell migration during development. We found that the RacGAP beta2-chimaerin (chimerin) bound to EphA2 and EphA4 and inactivated Rac1 in response to ephrinA1 stimulation. EphA4 bound to beta2-chimaerin through its kinase domain and promoted binding of Rac1 to beta2-chimaerin. In addition, knockdown of endogenous beta2-chimaerin blocked ephrinA1-induced suppression of cell migration. These results suggest that beta2-chimaerin is activated by EphA receptors and mediates the EphA receptor-dependent regulation of cell migration.
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Affiliation(s)
- Shingo Takeuchi
- Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
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21
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Siliceo M, Mérida I. T cell receptor-dependent tyrosine phosphorylation of beta2-chimaerin modulates its Rac-GAP function in T cells. J Biol Chem 2009; 284:11354-63. [PMID: 19201754 DOI: 10.1074/jbc.m806098200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The actin cytoskeleton has an important role in the organization and function of the immune synapse during antigen recognition. Dynamic rearrangement of the actin cytoskeleton in response to T cell receptor (TCR) triggering requires the coordinated activation of Rho family GTPases that cycle between active and inactive conformations. This is controlled by GTPase-activating proteins (GAP), which regulate inactivation of Rho GTPases, and guanine exchange factors, which mediate their activation. Whereas much attention has centered on guanine exchange factors for Rho GTPases in T cell activation, the identity and functional roles of the GAP in this process are largely unknown. We previously reported beta2-chimaerin as a diacylglycerol-regulated Rac-GAP that is expressed in T cells. We now demonstrate Lck-dependent phosphorylation of beta2-chimaerin in response to TCR triggering. We identify Tyr-153 as the Lck-dependent phosphorylation residue and show that its phosphorylation negatively regulates membrane stabilization of beta2-chimaerin, decreasing its GAP activity to Rac. This study establishes the existence of TCR-dependent regulation of beta2-chimaerin and identifies a novel mechanism for its inactivation.
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Affiliation(s)
- María Siliceo
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, E-28049 Madrid, Spain
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22
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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.
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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
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23
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Colón-González F, Leskow FC, Kazanietz MG. Identification of an autoinhibitory mechanism that restricts C1 domain-mediated activation of the Rac-GAP alpha2-chimaerin. J Biol Chem 2008; 283:35247-57. [PMID: 18826946 DOI: 10.1074/jbc.m806264200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Chimaerins are a family of GTPase activating proteins (GAPs) for the small G-protein Rac that have gained recent attention due to their important roles in development, cancer, neuritogenesis, and T-cell function. Like protein kinase C isozymes, chimaerins possess a C1 domain capable of binding phorbol esters and the lipid second messenger diacylglycerol (DAG) in vitro. Here we identified an autoinhibitory mechanism in alpha2-chimaerin that restricts access of phorbol esters and DAG, thereby limiting its activation. Although phorbol 12-myristate 13-acetate (PMA) caused limited translocation of wild-type alpha2-chimaerin to the plasma membrane, deletion of either N- or C-terminal regions greatly sensitize alpha2-chimaerin for intracellular redistribution and activation. Based on modeling analysis that revealed an occlusion of the ligand binding site in the alpha2-chimaerin C1 domain, we identified key amino acids that stabilize the inactive conformation. Mutation of these sites renders alpha2-chimaerin hypersensitive to C1 ligands, as reflected by its enhanced ability to translocate in response to PMA and to inhibit Rac activity and cell migration. Notably, in contrast to PMA, epidermal growth factor promotes full translocation of alpha2-chimaerin in a phospholipase C-dependent manner, but not of a C1 domain mutant with reduced affinity for DAG (P216A-alpha2-chimaerin). Therefore, DAG generation and binding to the C1 domain are required but not sufficient for epidermal growth factor-induced alpha2-chimaerin membrane association. Our studies suggest a role for DAG in anchoring rather than activation of alpha2-chimaerin. Like other DAG/phorbol ester receptors, including protein kinase C isozymes, alpha2-chimaerin is subject to autoinhibition by intramolecular contacts, suggesting a highly regulated mechanism for the activation of this Rac-GAP.
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Affiliation(s)
- Francheska Colón-González
- Department of Pharmacology and Institute for Translational Medicine and Therapeutics (ITMAT), University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA
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