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Expression of Non-T Cell Activation Linker (NTAL) in Jurkat Cells Negatively Regulates TCR Signaling: Potential Role in Rheumatoid Arthritis. Int J Mol Sci 2023; 24:ijms24054574. [PMID: 36902005 PMCID: PMC10003381 DOI: 10.3390/ijms24054574] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 02/20/2023] [Accepted: 02/23/2023] [Indexed: 03/02/2023] Open
Abstract
T lymphocytes are key players in adaptive immune responses through the recognition of peptide antigens through the T Cell Receptor (TCR). After TCR engagement, a signaling cascade is activated, leading to T cell activation, proliferation, and differentiation into effector cells. Delicate control of activation signals coupled to the TCR is needed to avoid uncontrolled immune responses involving T cells. It has been previously shown that mice deficient in the expression of the adaptor NTAL (Non-T cell activation linker), a molecule structurally and evolutionarily related to the transmembrane adaptor LAT (Linker for the Activation of T cells), develop an autoimmune syndrome characterized by the presence of autoantibodies and enlarged spleens. In the present work we intended to deepen investigation into the negative regulatory functions of the NTAL adaptor in T cells and its potential relationship with autoimmune disorders. For this purpose, in this work we used Jurkat cells as a T cell model, and we lentivirally transfected them to express the NTAL adaptor in order to analyze the effect on intracellular signals associated with the TCR. In addition, we analyzed the expression of NTAL in primary CD4+ T cells from healthy donors and Rheumatoid Arthritis (RA) patients. Our results showed that NTAL expression in Jurkat cells decreased calcium fluxes and PLC-γ1 activation upon stimulation through the TCR complex. Moreover, we showed that NTAL was also expressed in activated human CD4+ T cells, and that the increase of its expression was reduced in CD4+ T cells from RA patients. Our results, together with previous reports, suggest a relevant role for the NTAL adaptor as a negative regulator of early intracellular TCR signaling, with a potential implication in RA.
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2
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Shaik GM, Draberova L, Cernohouzova S, Tumova M, Bugajev V, Draber P. Pentacyclic triterpenoid ursolic acid interferes with mast cell activation via a lipid-centric mechanism affecting FcεRI signalosome functions. J Biol Chem 2022; 298:102497. [PMID: 36115460 PMCID: PMC9587013 DOI: 10.1016/j.jbc.2022.102497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 11/20/2022] Open
Abstract
Pentacyclic triterpenoids, including ursolic acid (UA), are bioactive compounds with multiple biological activities involving anti-inflammatory effects. However, the mode of their action on mast cells, key players in the early stages of allergic inflammation, and underlying molecular mechanisms remain enigmatic. To better understand the effect of UA on mast cell signaling, here we examined the consequences of short-term treatment of mouse bone marrow-derived mast cells with UA. Using IgE-sensitized and antigen- or thapsigargin-activated cells, we found that 15 min exposure to UA inhibited high affinity IgE receptor (FcεRI)–mediated degranulation, calcium response, and extracellular calcium uptake. We also found that UA inhibited migration of mouse bone marrow-derived mast cells toward antigen but not toward prostaglandin E2 and stem cell factor. Compared to control antigen-activated cells, UA enhanced the production of tumor necrosis factor-α at the mRNA and protein levels. However, secretion of this cytokine was inhibited. Further analysis showed that UA enhanced tyrosine phosphorylation of the SYK kinase and several other proteins involved in the early stages of FcεRI signaling, even in the absence of antigen activation, but inhibited or reduced their further phosphorylation at later stages. In addition, we show that UA induced changes in the properties of detergent-resistant plasma membrane microdomains and reduced antibody-mediated clustering of the FcεRI and glycosylphosphatidylinositol-anchored protein Thy-1. Finally, UA inhibited mobility of the FcεRI and cholesterol. These combined data suggest that UA exerts its effects, at least in part, via lipid-centric plasma membrane perturbations, hence affecting the functions of the FcεRI signalosome.
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Affiliation(s)
- Gouse M Shaik
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic; Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Lubica Draberova
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Sara Cernohouzova
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Magda Tumova
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Viktor Bugajev
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Petr Draber
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic.
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3
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TNK1 is a ubiquitin-binding and 14-3-3-regulated kinase that can be targeted to block tumor growth. Nat Commun 2021; 12:5337. [PMID: 34504101 PMCID: PMC8429728 DOI: 10.1038/s41467-021-25622-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 08/20/2021] [Indexed: 02/08/2023] Open
Abstract
TNK1 is a non-receptor tyrosine kinase with poorly understood biological function and regulation. Here, we identify TNK1 dependencies in primary human cancers. We also discover a MARK-mediated phosphorylation on TNK1 at S502 that promotes an interaction between TNK1 and 14-3-3, which sequesters TNK1 and inhibits its kinase activity. Conversely, the release of TNK1 from 14-3-3 allows TNK1 to cluster in ubiquitin-rich puncta and become active. Active TNK1 induces growth factor-independent proliferation of lymphoid cells in cell culture and mouse models. One unusual feature of TNK1 is a ubiquitin-association domain (UBA) on its C-terminus. Here, we characterize the TNK1 UBA, which has high affinity for poly-ubiquitin. Point mutations that disrupt ubiquitin binding inhibit TNK1 activity. These data suggest a mechanism in which TNK1 toggles between 14-3-3-bound (inactive) and ubiquitin-bound (active) states. Finally, we identify a TNK1 inhibitor, TP-5801, which shows nanomolar potency against TNK1-transformed cells and suppresses tumor growth in vivo.
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4
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Mandal JP, Shiue CN, Chen YC, Lee MC, Yang HH, Chang HH, Hu CT, Liao PC, Hui LC, You RI, Wu WS. PKCδ mediates mitochondrial ROS generation and oxidation of HSP60 to relieve RKIP inhibition on MAPK pathway for HCC progression. Free Radic Biol Med 2021; 163:69-87. [PMID: 33307168 DOI: 10.1016/j.freeradbiomed.2020.12.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 11/25/2020] [Accepted: 12/01/2020] [Indexed: 12/15/2022]
Abstract
Both protein kinase C (PKC) and reactive oxygen species (ROS) are well-known signaling messengers cross-talking with each other to activate mitogen-activated protein kinases (MAPKs) for progression of hepatocellular carcinoma (HCC). However, the underlying mechanisms are not well elucidated. Especially, whether mitochondrial ROS (mtROS) is involved and how it triggers MAPK signaling are intriguing. In this study, we found mtROS generation and phosphorylation of MAPKs were mediated by PKCδ in HCCs treated with the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Heat shock protein 60 (HSP60), one of the chaperones in mitochondria was the major protein oxidized in TPA-treated HCCs. Moreover, depletion of HSP60 or expression of HSP60 cysteine mutant prevented TPA-induced phosphorylation of MAPKs. To delineate how HSP60 mediated MAPK activation, the role of Raf kinase inhibitor protein (RKIP), a negative regulator of MAPK, was investigated. TPA dissociated RKIP from HSP60 in both mitochondria and cytosol, concurrently with translocation of HSP60 and MAPK from mitochondria to cytosol, which was associated with robust phosphorylation of MAPKs in the cytosol. Moreover, TPA induced opposite phenotypical changes of HCCs, G1 cell cycle arrest, and cell migration, which were prevented by mtROS scavengers and depletion of PKCδ and HSP60. Consistently, TPA increased the migration-related genes, hydrogen peroxide inducible clone5, matrix metalloproteinase-1/3, lamininγ2, and suppressed the cell cycle regulator cyclin E1 (CCNE1) via PKCδ/mtROS/HSP60/MAPK-axis. Finally, c-jun and c-fos were required for TPA-induced expression of the migration-related genes and a novel microRNA, miR-6134, was responsible for TPA-induced suppression of CCNE1. In conclusion, PKCδ cross-talked with mtROS to trigger HSP60 oxidation for release of RKIP to activate MAPK, regulating gene expression for migration, and G1 cell cycle arrest in HCC. Targeted therapy aiming at key players like PKCδ, RKIP, and HSP60 is promising for preventing HCC progression.
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Affiliation(s)
| | - Chiou-Nan Shiue
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan.
| | - Yen-Cheng Chen
- Division of General Surgery, Department of Surgery, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical foundation, Hualien, Taiwan; School of Medicine, Tzu Chi University, Hualien, Taiwan.
| | - Ming-Che Lee
- Division of General Surgery, Department of Surgery, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical foundation, Hualien, Taiwan; School of Medicine, Tzu Chi University, Hualien, Taiwan.
| | - Hsueh-Hui Yang
- Department of Medical Research, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, 970, Taiwan.
| | - Hsin-Hou Chang
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan; Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan.
| | - Chi-Tan Hu
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan; Division of Gastroenterology, Department of Medicine, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical foundation, Hualien, Taiwan; Research Centre for Hepatology, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical foundation, Hualien, Taiwan.
| | - Pei-Chen Liao
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan.
| | - Lin-Ching Hui
- Department of Laboratory Medicine and Biotechnology, College of Medicine, Tzu Chi University, Hualien, Taiwan.
| | - Ren-In You
- Department of Laboratory Medicine and Biotechnology, College of Medicine, Tzu Chi University, Hualien, Taiwan.
| | - Wen-Sheng Wu
- Division of General Surgery, Department of Surgery, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical foundation, Hualien, Taiwan; Department of Laboratory Medicine and Biotechnology, College of Medicine, Tzu Chi University, Hualien, Taiwan.
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5
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Song W, Kim LC, Han W, Hou Y, Edwards DN, Wang S, Blackwell TS, Cheng F, Brantley-Sieders DM, Chen J. Phosphorylation of PLCγ1 by EphA2 Receptor Tyrosine Kinase Promotes Tumor Growth in Lung Cancer. Mol Cancer Res 2020; 18:1735-1743. [PMID: 32753469 PMCID: PMC7641970 DOI: 10.1158/1541-7786.mcr-20-0075] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 07/07/2020] [Accepted: 07/20/2020] [Indexed: 12/23/2022]
Abstract
EphA2 receptor tyrosine kinase (RTK) is often expressed at high levels in cancer and has been shown to regulate tumor growth and metastasis across multiple tumor types, including non-small cell lung cancer. A number of signaling pathways downstream of EphA2 RTK have been identified; however, mechanisms of EphA2 proximal downstream signals are less well characterized. In this study, we used a yeast-two-hybrid screen to identify phospholipase C gamma 1 (PLCγ1) as a novel EphA2 interactor. EphA2 interacts with PLCγ1 and the kinase activity of EphA2 was required for phosphorylation of PLCγ1. In human lung cancer cells, genetic or pharmacologic inhibition of EphA2 decreased phosphorylation of PLCγ1 and loss of PLCγ1 inhibited tumor cell growth in vitro. Knockout of PLCγ1 by CRISPR-mediated genome editing also impaired tumor growth in a KrasG12D-p53-Lkb1 murine lung tumor model. Collectively, these data show that the EphA2-PLCγ1 signaling axis promotes tumor growth of lung cancer and provides rationale for disruption of this signaling axis as a potential therapeutic option. IMPLICATIONS: The EphA2-PLCG1 signaling axis promotes tumor growth of non-small cell lung cancer and can potentially be targeted as a therapeutic option.
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Affiliation(s)
- Wenqiang Song
- Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Veterans Affairs Medical Center, Tennessee Valley Healthcare System, Nashville, Tennessee
| | - Laura C Kim
- Program in Cancer Biology, Vanderbilt University, Nashville, Tennessee
| | - Wei Han
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Yuan Hou
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - Deanna N Edwards
- Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Shan Wang
- Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Timothy S Blackwell
- Veterans Affairs Medical Center, Tennessee Valley Healthcare System, Nashville, Tennessee
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee
| | - Feixiong Cheng
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio
- Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Dana M Brantley-Sieders
- Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.
- Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jin Chen
- Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.
- Veterans Affairs Medical Center, Tennessee Valley Healthcare System, Nashville, Tennessee
- Program in Cancer Biology, Vanderbilt University, Nashville, Tennessee
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee
- Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
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6
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Arbulo-Echevarria MM, Vico-Barranco I, Narbona-Sánchez I, García-Cózar F, Miazek A, Aguado E. Increased Protein Stability and Interleukin-2 Production of a LAT G131D Variant With Possible Implications for T Cell Anergy. Front Cell Dev Biol 2020; 8:561503. [PMID: 33042995 PMCID: PMC7517355 DOI: 10.3389/fcell.2020.561503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 08/13/2020] [Indexed: 11/13/2022] Open
Abstract
The adaptor LAT plays a crucial role in the transduction of signals coming from the TCR/CD3 complex. Phosphorylation of some of its tyrosines generates recruitment sites for other cytosolic signaling molecules. Tyrosine 132 in human LAT is essential for PLC-γ activation and calcium influx generation. It has been recently reported that a conserved glycine residue preceding tyrosine 132 decreases its phosphorylation kinetics, which constitutes a mechanism for ligand discrimination. Here we confirm that a LAT mutant in which glycine 131 has been substituted by an aspartate (LATG131D) increases phosphorylation of Tyr132, PLC-γ activation and calcium influx generation. Interestingly, the LATG131D mutant has a slower protein turnover while being equally sensitive to Fas-mediated protein cleavage by caspases. Moreover, J.CaM2 cells expressing LATG131D secrete greater amounts of interleukin-2 (IL-2) in response to CD3/CD28 engagement. However, despite this increased IL-2 secretion, J.CaM2 cells expressing the LATG131D mutant are more sensitive to inhibition of IL-2 production by pre-treatment with anti-CD3, which points to a possible role of this residue in the generation of anergy. Our results suggest that the increased kinetics of LAT Tyr132 phosphorylation could contribute to the establishment of T cell anergy, and thus constitutes an earliest known intracellular event responsible for the induction of peripheral tolerance.
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Affiliation(s)
| | | | | | - Francisco García-Cózar
- Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain.,Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | - Arkadiusz Miazek
- Department of Biochemistry and Molecular Biology, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
| | - Enrique Aguado
- Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain.,Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
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7
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Arbulo-Echevarria MM, Narbona-Sánchez I, Fernandez-Ponce CM, Vico-Barranco I, Rueda-Ygueravide MD, Dustin ML, Miazek A, Duran-Ruiz MC, García-Cózar F, Aguado E. A Stretch of Negatively Charged Amino Acids of Linker for Activation of T-Cell Adaptor Has a Dual Role in T-Cell Antigen Receptor Intracellular Signaling. Front Immunol 2018; 9:115. [PMID: 29456532 PMCID: PMC5801411 DOI: 10.3389/fimmu.2018.00115] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 01/15/2018] [Indexed: 11/13/2022] Open
Abstract
The adaptor protein linker for activation of T cells (LAT) has an essential role transducing activatory intracellular signals coming from the TCR/CD3 complex. Previous reports have shown that upon T-cell activation, LAT interacts with the tyrosine kinase Lck, leading to the inhibition of its kinase activity. LAT-Lck interaction seemed to depend on a stretch of negatively charged amino acids in LAT. Here, we have substituted this segment of LAT between amino acids 113 and 126 with a non-charged segment and expressed the mutant LAT (LAT-NIL) in J.CaM2 cells in order to analyze TCR signaling. Substitution of this segment in LAT prevented the activation-induced interaction with Lck. Moreover, cells expressing this mutant form of LAT showed a statistically significant increase of proximal intracellular signals such as phosphorylation of LAT in tyrosine residues 171 and 191, and also enhanced ZAP70 phosphorylation approaching borderline statistical significance (p = 0.051). Nevertheless, downstream signals such as Ca2+ influx or MAPK pathways were partially inhibited. Overall, our data reveal that LAT-Lck interaction constitutes a key element regulating proximal intracellular signals coming from the TCR/CD3 complex.
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Affiliation(s)
- Mikel M Arbulo-Echevarria
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | - Isaac Narbona-Sánchez
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | - Cecilia M Fernandez-Ponce
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | - Inmaculada Vico-Barranco
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | | | - Michael L Dustin
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, The Kennedy Institute of Rheumatology, The University of Oxford, Headington, United Kingdom
| | - Arkadiusz Miazek
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - Mª Carmen Duran-Ruiz
- Department of Biomedicine, Biotechnology and Public Health (Biochemistry), University of Cádiz, Cádiz, Spain.,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
| | - Francisco García-Cózar
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain.,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
| | - Enrique Aguado
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain.,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
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8
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Jang HJ, Suh PG, Lee YJ, Shin KJ, Cocco L, Chae YC. PLCγ1: Potential arbitrator of cancer progression. Adv Biol Regul 2018; 67:179-189. [PMID: 29174396 DOI: 10.1016/j.jbior.2017.11.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 11/07/2017] [Accepted: 11/07/2017] [Indexed: 06/07/2023]
Abstract
Phospholipase C (PLC) is an essential mediator of cellular signaling. PLC regulates multiple cellular processes by generating bioactive molecules such as inositol-1,4,5-triphosphate (IP3) and diacylglycerol (DAG). These products propagate and regulate cellular signaling via calcium (Ca2+) mobilization and activation of protein kinase C (PKC), other kinases, and ion channels. PLCγ1, one of the primary subtypes of PLC, is directly activated by membrane receptors, including receptor tyrosine kinases (RTKs), and adhesion receptors such as integrin. PLCγ1 mediates signaling through direct interactions with other signaling molecules via SH domains, as well as its lipase activity. PLCγ1 is frequently enriched and mutated in various cancers, and is involved in the processes of tumorigenesis, including proliferation, migration, and invasion. Although many studies have suggested that PLCγ functions in cell mobility rather than proliferation in cancer, questions remain as to whether PLCγ regulates mitogenesis and whether PLCγ promotes or inhibits proliferation. Moreover, how PLCγ regulates cancer-associated cellular processes and the interplay among other proteins involved in cancer progression have yet to be fully elucidated. In this review, we discuss the current understanding of the role of PLCγ1 in cancer mobility and proliferation.
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Affiliation(s)
- Hyun-Jun Jang
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Pann-Ghill Suh
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Yu Jin Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Kyeong Jin Shin
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Lucio Cocco
- Department of Biomedical and Neuromotor Sciences, Cellular Signalling Laboratory, Institute of Human Anatomy, University of Bologna, Bologna, Italy
| | - Young Chan Chae
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.
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9
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Carboneau BA, Allan JA, Townsend SE, Kimple ME, Breyer RM, Gannon M. Opposing effects of prostaglandin E 2 receptors EP3 and EP4 on mouse and human β-cell survival and proliferation. Mol Metab 2017; 6:548-559. [PMID: 28580285 PMCID: PMC5444094 DOI: 10.1016/j.molmet.2017.04.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 03/30/2017] [Accepted: 04/03/2017] [Indexed: 01/02/2023] Open
Abstract
OBJECTIVE Hyperglycemia and systemic inflammation, hallmarks of Type 2 Diabetes (T2D), can induce the production of the inflammatory signaling molecule Prostaglandin E2 (PGE2) in islets. The effects of PGE2 are mediated by its four receptors, E-Prostanoid Receptors 1-4 (EP1-4). EP3 and EP4 play opposing roles in many cell types due to signaling through different G proteins, Gi and GS, respectively. We previously found that EP3 and EP4 expression are reciprocally regulated by activation of the FoxM1 transcription factor, which promotes β-cell proliferation and survival. Our goal was to determine if EP3 and EP4 regulate β-cell proliferation and survival and, if so, to elucidate the downstream signaling mechanisms. METHODS β-cell proliferation was assessed in mouse and human islets ex vivo treated with selective agonists and antagonists for EP3 (sulprostone and DG-041, respectively) and EP4 (CAY10598 and L-161,982, respectively). β-cell survival was measured in mouse and human islets treated with the EP3- and EP4-selective ligands in conjunction with a cytokine cocktail to induce cell death. Changes in gene expression and protein phosphorylation were analyzed in response to modulation of EP3 and EP4 activity in mouse islets. RESULTS Blockade of EP3 enhanced β-cell proliferation in young, but not old, mouse islets in part through phospholipase C (PLC)-γ1 activity. Blocking EP3 also increased human β-cell proliferation. EP4 modulation had no effect on ex vivo proliferation alone. However, blockade of EP3 in combination with activation of EP4 enhanced human, but not mouse, β-cell proliferation. In both mouse and human islets, EP3 blockade or EP4 activation enhanced β-cell survival in the presence of cytokines. EP4 acts in a protein kinase A (PKA)-dependent manner to increase mouse β-cell survival. In addition, the positive effects of FoxM1 activation on β-cell survival are inhibited by EP3 and dependent on EP4 signaling. CONCLUSIONS Our results identify EP3 and EP4 as novel regulators of β-cell proliferation and survival in mouse and human islets ex vivo.
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Key Words
- COX-2, cyclooxygenase-2
- Cell death
- DAG, diacylglycerol
- EP1-4, E-Prostanoid Receptors 1-4
- GPCR, G protein-coupled receptor
- IP3, inositol 1,4,5-trisphosphate
- PGE2, prostaglandin E2
- PKA, protein kinase A
- PL, placental lactogen
- PLC, phospholipase C
- PT, pertussis toxin
- Pancreatic β-cell
- Proliferation
- Prostaglandin E2
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Affiliation(s)
- Bethany A Carboneau
- Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN, USA.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.,Program in Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Jack A Allan
- School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Shannon E Townsend
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Michelle E Kimple
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA.,William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Richard M Breyer
- Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN, USA.,Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Maureen Gannon
- Department of Veterans Affairs, Tennessee Valley Health Authority, Nashville, TN, USA.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.,Program in Developmental Biology, Vanderbilt University, Nashville, TN, USA.,Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.,Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
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10
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Immunoglobulin-like domain 4-mediated ligand-independent dimerization triggers VEGFR-2 activation in HUVECs and VEGFR2-positive breast cancer cells. Breast Cancer Res Treat 2017; 163:423-434. [PMID: 28303365 DOI: 10.1007/s10549-017-4189-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 03/06/2017] [Indexed: 02/07/2023]
Abstract
PURPOSE The extracellular region (EC) of the vascular endothelial growth factor (VEGF) receptor-2 (VEGFR-2) contains seven immunoglobulin-like (Ig-like) domains that are required for specific ligand binding and receptor dimerization. Studies of domain 4-7 deletions and substitutions provided insights into the interaction between receptors in the absence of VEGF. In this study, we investigated the effect of domain 4 in ligand-independent VEGFR-2 dimerization and activation in human vascular endothelial cells and human breast cancer cells. METHODS To confirm the role of domain 4 in ligand-independent receptor dimerization and activation, two VEGFR-2 fragments with and without domain 4, KFP1 and KFP2, were generated by recombinant DNA technology. We measured the affinity of KFP1 and KFP2 with VEGFR-2, and the roles of KFP1 and FKP2 in dimerization and phosphorylation of VEGFR-2. We also evaluated the effect of KFP1 and FKP2 on cell proliferation and migration in HUVECs and in human breast cancer cells. RESULTS We showed that KFP1 did not affect the interaction of VEGFR-2 and VEGF but bound VEGFR-2 in the absence of VEGF. Furthermore, cross-linking and cross-linking immunoblotting demonstrated that KFP1 could form a complex with VEGFR-2, which resulted in VEGFR-2 dimerization in the absence of VEGF. Importantly, we found that the KDR fragment with domain 4 induced phosphorylation of VEGFR-2, as well as phosphorylation of downstream receptor kinases in HUVECs and VEGFR-2-positive breast cancer cells. Consistent with these results, this ligand-independent activation of VEGFR-2 also promoted downstream signaling and cell proliferation and migration. CONCLUSIONS The domain 4 of VEGFR-2 plays an important role in the interaction between VEGFR receptors in the absence of VEGF.
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11
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Abstract
The ErbB receptor family, also known as the EGF receptor family or type I receptor family, includes the epidermal growth factor (EGF) receptor (EGFR) or ErbB1/Her1, ErbB2/Her2, ErbB3/Her3, and ErbB4/Her4. Among all RTKs, EGFR was the first RTK identified and the first one linked to cancer. Thus, EGFR has also been the most intensively studied among all RTKs. ErbB receptors are activated after homodimerization or heterodimerization. The ErbB family is unique among the various groups of receptor tyrosine kinases (RTKs) in that ErbB3 has impaired kinase activity, while ErbB2 does not have a direct ligand. Therefore, heterodimerization is an important mechanism that allows the activation of all ErbB receptors in response to ligand stimulation. The activated ErbB receptors bind to many signaling proteins and stimulate the activation of many signaling pathways. The specificity and potency of intracellular signaling pathways are determined by positive and negative regulators, the specific composition of activating ligand(s), receptor dimer components, and the diverse range of proteins that associate with the tyrosine phosphorylated C-terminal domain of the ErbB receptors. ErbB receptors are overexpressed or mutated in many cancers, especially in breast cancer, ovarian cancer, and non-small cell lung cancer. The overexpression and overactivation of ErbB receptors are correlated with poor prognosis, drug resistance, cancer metastasis, and lower survival rate. ErbB receptors, especially EGFR and ErbB2 have been the primary choices as targets for developing cancer therapies.
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Affiliation(s)
- Zhixiang Wang
- Signal Transduction Research Group, Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, 835 MSB, 114 St NW, Edmonton, AB, Canada, T6G 2H7.
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Wang Z. Transactivation of Epidermal Growth Factor Receptor by G Protein-Coupled Receptors: Recent Progress, Challenges and Future Research. Int J Mol Sci 2016; 17:ijms17010095. [PMID: 26771606 PMCID: PMC4730337 DOI: 10.3390/ijms17010095] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 01/06/2016] [Accepted: 01/07/2016] [Indexed: 02/06/2023] Open
Abstract
Both G protein-coupled receptors (GPCRs) and receptor-tyrosine kinases (RTKs) regulate large signaling networks, control multiple cell functions and are implicated in many diseases including various cancers. Both of them are also the top therapeutic targets for disease treatment. The discovery of the cross-talk between GPCRs and RTKs connects these two vast signaling networks and complicates the already complicated signaling networks that regulate cell signaling and function. In this review, we focus on the transactivation of epidermal growth factor receptor (EGFR), a subfamily of RTKs, by GPCRs. Since the first report of EGFR transactivation by GPCR, significant progress has been made including the elucidation of the mechanisms underlying the transactivation. Here, we first provide a basic picture for GPCR, EGFR and EGFR transactivation by GPCR. We then discuss the progress made in the last five years and finally provided our view of the future challenge and future researches needed to overcome these challenges.
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Affiliation(s)
- Zhixiang Wang
- The Department of Medical Genetics and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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13
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EGF stimulates the activation of EGF receptors and the selective activation of major signaling pathways during mitosis. Cell Signal 2015; 27:638-51. [DOI: 10.1016/j.cellsig.2014.11.030] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 11/10/2014] [Accepted: 11/24/2014] [Indexed: 11/18/2022]
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Fibroblast growth factor acts upon the transcription of phospholipase C genes in human umbilical vein endothelial cells. Mol Cell Biochem 2013; 388:51-9. [PMID: 24242047 DOI: 10.1007/s11010-013-1898-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Accepted: 11/05/2013] [Indexed: 02/02/2023]
Abstract
Besides the control of calcium levels, the phosphoinositide-specific phospholipases C (PI-PLCs), the main players in the phosphoinositide signalling pathway, contribute to a number of cell activities. The expression of PI-PLCs is strictly tissue specific and evidence suggests that it varies under different conditions, such as tumour progression or cell activation. In previous studies, we obtained a complete panel of expression of PI-PLC isoforms in human umbilical vein endothelial cells (HUVEC), a widely used experimental model for endothelial cells (EC), and demonstrated that the expression of the PLC genes varies under inflammatory stimulation. The fibroblast growth factor (FGF) activates the PI-PLC γ1 isoform. In the present study, PI-PLC expression in FGF-treated HUVEC was performed using RT-PCR, observed 24 h after stimulation. The expression of selected genes after stimulation was perturbed, suggesting that FGF affects gene transcription in PI signalling as a possible mechanism of regulation of its activity upon the AkT-PLC pathway. The most efficient effects of FGF were recorded in the 3-6-h interval. To understand the complex events progressing in EC might provide useful insights for potential therapeutic strategies. The opportunity to manipulate the EC might offer a powerful tool of considerable practical and clinical importance.
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Phosphorylation of Rac1 T108 by extracellular signal-regulated kinase in response to epidermal growth factor: a novel mechanism to regulate Rac1 function. Mol Cell Biol 2013; 33:4538-51. [PMID: 24043306 DOI: 10.1128/mcb.00822-13] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Accumulating evidence has implicated Rho GTPases, including Rac1, in many aspects of cancer development. Recent findings suggest that phosphorylation might further contribute to the tight regulation of Rho GTPases. Interestingly, sequence analysis of Rac1 shows that Rac1 T108 within the (106)PNTP(109) motif is likely an extracellular signal-regulated kinase (ERK) phosphorylation site and that Rac1 also has an ERK docking site, (183)KKRKRKCLLL(192) (D site), at the C terminus. Indeed, we show here that both transfected and endogenous Rac1 interacts with ERK and that this interaction is mediated by its D site. Green fluorescent protein (GFP)-Rac1 is threonine (T) phosphorylated in response to epidermal growth factor (EGF), and EGF-induced Rac1 threonine phosphorylation is dependent on the activation of ERK. Moreover, mutant Rac1 with the mutation of T108 to alanine (A) is not threonine phosphorylated in response to EGF. In vitro ERK kinase assay further shows that pure active ERK phosphorylates purified Rac1 but not mutant Rac1 T108A. We also show that Rac1 T108 phosphorylation decreases Rac1 activity, partially due to inhibiting its interaction with phospholipase C-γ1 (PLC-γ1). T108 phosphorylation targets Rac1 to the nucleus, which isolates Rac1 from other guanine nucleotide exchange factors (GEFs) and hinders Rac1's role in cell migration. We conclude that Rac1 T108 is phosphorylated by ERK in response to EGF, which plays an important role in regulating Rac1.
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Qi Q, Ye K. The roles of PIKE in tumorigenesis. Acta Pharmacol Sin 2013; 34:991-7. [PMID: 23770988 PMCID: PMC3733165 DOI: 10.1038/aps.2013.71] [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: 03/17/2013] [Accepted: 04/28/2013] [Indexed: 01/22/2023] Open
Abstract
Tumorigenesis is the process by which normal cells evolve the capacity to evade and overcome the constraints usually placed upon their growth and survival. To ensure the integrity of organs and tissues, the balance of cell proliferation and cell death is tightly maintained. The proteins controlling this balance are either considered oncogenes, which promote tumorigenesis, or tumor suppressors, which prevent tumorigenesis. Phosphoinositide 3-kinase enhancer (PIKE) is a family of GTP-binding proteins that possess anti-apoptotic functions and play an important role in the central nervous system. Notably, accumulating evidence suggests that PIKE is a proto-oncogene involved in tumor progression. The PIKE gene (CENTG1) is amplified in a variety of human cancers, leading to the resistance against apoptosis and the enhancement of invasion. In this review, we will summarize the functions of PIKE proteins in tumorigenesis and discuss their potential implications in cancer therapy.
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Oxidative stress mediates the disruption of airway epithelial tight junctions through a TRPM2-PLCγ1-PKCα signaling pathway. Int J Mol Sci 2013; 14:9475-86. [PMID: 23629676 PMCID: PMC3676794 DOI: 10.3390/ijms14059475] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 03/18/2013] [Accepted: 04/16/2013] [Indexed: 11/16/2022] Open
Abstract
Oxidative stress has been implicated as an important contributing factor in the pathogenesis of several pulmonary inflammatory diseases. Previous studies have indicated a relationship between oxidative stress and the attenuation of epithelial tight junctions (TJs). In Human Bronchial Epithelial-16 cells (16HBE), we demonstrated the degradation of zonula occludens-1 (ZO-1), and claudin-2 exhibited a great dependence on the activation of the transient receptor potential melastatin (TRPM) 2 channel, phospholipase Cγ1 (PLCγ1) and the protein kinase Cα (PKCα) signaling cascade.
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Phospholipases of mineralization competent cells and matrix vesicles: roles in physiological and pathological mineralizations. Int J Mol Sci 2013; 14:5036-129. [PMID: 23455471 PMCID: PMC3634480 DOI: 10.3390/ijms14035036] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 01/24/2013] [Accepted: 01/25/2013] [Indexed: 02/08/2023] Open
Abstract
The present review aims to systematically and critically analyze the current knowledge on phospholipases and their role in physiological and pathological mineralization undertaken by mineralization competent cells. Cellular lipid metabolism plays an important role in biological mineralization. The physiological mechanisms of mineralization are likely to take place in tissues other than in bones and teeth under specific pathological conditions. For instance, vascular calcification in arteries of patients with renal failure, diabetes mellitus or atherosclerosis recapitulates the mechanisms of bone formation. Osteoporosis—a bone resorbing disease—and rheumatoid arthritis originating from the inflammation in the synovium are also affected by cellular lipid metabolism. The focus is on the lipid metabolism due to the effects of dietary lipids on bone health. These and other phenomena indicate that phospholipases may participate in bone remodelling as evidenced by their expression in smooth muscle cells, in bone forming osteoblasts, chondrocytes and in bone resorbing osteoclasts. Among various enzymes involved, phospholipases A1 or A2, phospholipase C, phospholipase D, autotaxin and sphingomyelinase are engaged in membrane lipid remodelling during early stages of mineralization and cell maturation in mineralization-competent cells. Numerous experimental evidences suggested that phospholipases exert their action at various stages of mineralization by affecting intracellular signaling and cell differentiation. The lipid metabolites—such as arachidonic acid, lysophospholipids, and sphingosine-1-phosphate are involved in cell signaling and inflammation reactions. Phospholipases are also important members of the cellular machinery engaged in matrix vesicle (MV) biogenesis and exocytosis. They may favour mineral formation inside MVs, may catalyse MV membrane breakdown necessary for the release of mineral deposits into extracellular matrix (ECM), or participate in hydrolysis of ECM. The biological functions of phospholipases are discussed from the perspective of animal and cellular knockout models, as well as disease implications, development of potent inhibitors and therapeutic interventions.
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Xie Z, Jiang Y, Liao EY, Chen Y, Pennypacker SD, Peng J, Chang SM. PIKE mediates EGFR proliferative signaling in squamous cell carcinoma cells. Oncogene 2012; 31:5090-8. [PMID: 22349826 DOI: 10.1038/onc.2012.10] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 12/30/2011] [Indexed: 11/08/2022]
Abstract
One of the key drivers for squamous cell carcinoma (SCC) proliferation is activation of the epidermal growth factor receptor (EGFR), a known proto-oncogene. However, the mechanism of EGFR-dependent SCC proliferation remains unclear. Our previous studies indicate that epidermal growth factor (EGF)-induced SCC cell proliferation requires the SH3 domain of phospholipase C-γ1 (PLC-γ1), but not its catalytic activity. The SH3 domain of PLC-γ1 is known to activate the short form of nuclear phosphatidylinositol 3-kinase enhancer (PIKE) that enhances the activity of nuclear class Ia phosphatidylinositol 3-kinase (PI3K) required for proliferation. However, PIKE has been described for more than a decade to be present exclusively in neuronal cells. In the present study, we found that PIKE was highly expressed in malignant human keratinocytes (SCC4 and SCC12B2) but had low expression in normal human keratinocytes. Immunohistochemical analysis showed strong nuclear staining of PIKE in human epidermal and tongue SCC specimens but little staining in the adjacent non-cancerous epithelium. Treatment of SCC4 cells with EGF-induced translocation of PLC-γ1 to the nucleus and binding of PLC-γ1 to the nuclear PIKE. Knockdown of PLC-γ1 or PIKE blocked EGF-induced activation of class Ia PI3K and protein kinase C-ζ and phosphorylation of nucleolin in the nucleus as well as EGF-induced SCC cell proliferation. However, inhibition of the catalytic activity of PLC-γ1 had little effect. These data suggest that PIKE has a critical role in EGF-induced SCC cell proliferation and may function as a proto-oncogene in SCC.
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Affiliation(s)
- Z Xie
- Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
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20
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Sun X, Zhang L, Tan H, Bao J, Strouthos C, Zhou X. Multi-scale agent-based brain cancer modeling and prediction of TKI treatment response: incorporating EGFR signaling pathway and angiogenesis. BMC Bioinformatics 2012; 13:218. [PMID: 22935054 PMCID: PMC3487967 DOI: 10.1186/1471-2105-13-218] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 08/08/2012] [Indexed: 12/04/2022] Open
Abstract
Background The epidermal growth factor receptor (EGFR) signaling pathway and angiogenesis in brain cancer act as an engine for tumor initiation, expansion and response to therapy. Since the existing literature does not have any models that investigate the impact of both angiogenesis and molecular signaling pathways on treatment, we propose a novel multi-scale, agent-based computational model that includes both angiogenesis and EGFR modules to study the response of brain cancer under tyrosine kinase inhibitors (TKIs) treatment. Results The novel angiogenesis module integrated into the agent-based tumor model is based on a set of reaction–diffusion equations that describe the spatio-temporal evolution of the distributions of micro-environmental factors such as glucose, oxygen, TGFα, VEGF and fibronectin. These molecular species regulate tumor growth during angiogenesis. Each tumor cell is equipped with an EGFR signaling pathway linked to a cell-cycle pathway to determine its phenotype. EGFR TKIs are delivered through the blood vessels of tumor microvasculature and the response to treatment is studied. Conclusions Our simulations demonstrated that entire tumor growth profile is a collective behaviour of cells regulated by the EGFR signaling pathway and the cell cycle. We also found that angiogenesis has a dual effect under TKI treatment: on one hand, through neo-vasculature TKIs are delivered to decrease tumor invasion; on the other hand, the neo-vasculature can transport glucose and oxygen to tumor cells to maintain their metabolism, which results in an increase of cell survival rate in the late simulation stages.
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Affiliation(s)
- Xiaoqiang Sun
- Department of Radiology, The Methodist Hospital Research Institute, Weil Cornell Medical College, Houston, TX 77030, USA
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21
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Kawashima I, Liu Z, Mullany LK, Mihara T, Richards JS, Shimada M. EGF-like factors induce expansion of the cumulus cell-oocyte complexes by activating calpain-mediated cell movement. Endocrinology 2012; 153:3949-59. [PMID: 22673225 PMCID: PMC3404342 DOI: 10.1210/en.2012-1059] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Cumulus cell-oocyte complex (COC) expansion is obligatory for LH-induced ovulation and is initiated by LH induction of the epidermal growth factor (EGF)-like factors that mediate the synthesis of the hyaluronan-rich matrix and hyaluronan-stabilizing factors. COC expansion also involves the movement of cumulus cells within the matrix by mechanisms that have not been characterized. We document herein that two proteases, calpain 2 and to a lesser extent calpain 1, are expressed in cumulus cells and that the proteolytic activity of these enzymes is rapidly and significantly increased in COC isolated from human chorionic gonadotropin-induced ovulatory follicles in vivo. Stimulation of calpain activity was associated with proteolytic degradation of paxillin and talin (two components of focal adhesion complexes), cell detachment, and the formation of cell surface bleb-like protrusions. Injection of a calpain inhibitor in vivo reduced 1) human chorionic gonadotropin-stimulated calpain enzyme activity, 2) cell detachment, 3) membrane protrusion formation, and 4) COC expansion by mechanisms that did not alter Has2 expression. During EGF-like factor induction of COC expansion in culture, calpain activity was increased by ERK1/2 and intracellular Ca(2+) signaling pathways. Inhibition of calpain activity in cultured COC blocked cumulus cell detachment, protrusion formation, and the vigorous movement of cumulus cells. As a consequence, COC expansion was impaired. Collectively, these results show that two highly coordinated processes control COC expansion. One process involves the synthesis of the hyaluronan matrix, and the other mediates cumulus cell detachment and movement. The latter are controlled by calpain activation downstream of the EGF receptor activation of the Ca(2+) pathway and ERK1/2 pathways.
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Affiliation(s)
- Ikko Kawashima
- Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-8528, Japan
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22
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Jain A, Olovsson M, Burton GJ, Yung HW. Endothelin-1 induces endoplasmic reticulum stress by activating the PLC-IP(3) pathway: implications for placental pathophysiology in preeclampsia. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 180:2309-20. [PMID: 22503784 DOI: 10.1016/j.ajpath.2012.03.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 02/23/2012] [Accepted: 03/01/2012] [Indexed: 02/04/2023]
Abstract
Recent evidence implicates placental endoplasmic reticulum (ER) stress in the pathophysiological characteristics of preeclampsia. Herein, we investigate whether endothelin (ET)-1, which induces Ca(2+) release from the ER, can induce placental ER stress. Loss of ER Ca(2+) homeostasis impairs post-translational modification of proteins, triggering ER stress-response pathways. IHC confirmed the presence of both ET-1 and its receptors in the syncytiotrophoblast. Protein levels and immunoreactivity of ET-1 and the endothelin B receptor (ETBR) were increased in preeclamptic samples compared with normotensive controls. JEG-3 and BeWo choriocarcinoma cells treated with ET-1 displayed an increase in ER stress markers. ET-1 induced phospho-activation of the ETBR. Treating cells with BQ788, an ETBR antagonist, or small-interfering RNA knockdown of the receptor inhibited induction of ER stress. ET-1 also stimulated p-phospholipase C (PLC)γ1 levels. By using inhibitors of PLC activation, U73122, and the inositol 1,4,5-triphosphate (IP(3)) receptor, xestospongin-C, we demonstrated that ET-1 induces ER stress via the PLC-IP(3) pathway. Furthermore, ET-1 levels increased in the syncytiotrophoblast of explants from normal placentas after hypoxia-reoxygenation in vitro. Conditioned medium from hypoxia-reoxygenation explants also contained higher ET-1 levels, which induced ER stress in JEG-3 cells that was abolished by an ET-1-neutralizing antibody. Collectively, the data show that ET-1 induced ER stress in trophoblasts via the ETBR and initiation of signaling through the PLC-IP(3) pathway, with the potential for autocrine stimulation.
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Affiliation(s)
- Arjun Jain
- Center for Trophoblast Research, Department of Physiology Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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Yang YR, Choi JH, Chang JS, Kwon HM, Jang HJ, Ryu SH, Suh PG. Diverse cellular and physiological roles of phospholipase C-γ1. Adv Biol Regul 2012; 52:138-151. [PMID: 21964416 DOI: 10.1016/j.advenzreg.2011.09.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 09/19/2011] [Indexed: 05/31/2023]
Affiliation(s)
- Yong Ryoul Yang
- School of Nano-Biotechnology and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 689-798, Republic of Korea
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San Luis B, Sondgeroth B, Nassar N, Carpino N. Sts-2 is a phosphatase that negatively regulates zeta-associated protein (ZAP)-70 and T cell receptor signaling pathways. J Biol Chem 2011; 286:15943-54. [PMID: 21393235 PMCID: PMC3091203 DOI: 10.1074/jbc.m110.177634] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2010] [Revised: 03/06/2011] [Indexed: 11/06/2022] Open
Abstract
T cell activity is controlled in large part by the T cell receptor (TCR). The TCR detects the presence of foreign pathogens and activates the T cell-mediated immune reaction. Numerous intracellular signaling pathways downstream of the TCR are involved in the process of T cell activation. Negative regulation of these pathways helps prevent excessive and deleterious T cell responses. Two homologous proteins, Sts-1 and Sts-2, have been shown to function as critical negative regulators of TCR signaling. The phosphoglycerate mutase-like domain of Sts-1 (Sts-1(PGM)) has a potent phosphatase activity that contributes to the suppression of TCR signaling. The function of Sts-2(PGM) as a phosphatase has been less clear, principally because its intrinsic enzyme activity has been difficult to detect. Here, we demonstrate that Sts-2 regulates the level of tyrosine phosphorylation on targets within T cells, among them the critical T cell tyrosine kinase Zap-70. Utilizing new phosphorylated substrates, we demonstrate that Sts-2(PGM) has clear, albeit weak, phosphatase activity. We further pinpoint Sts-2 residues Glu-481, Ser-552, and Ser-582 as specificity determinants, in that an Sts-2(PGM) triple mutant in which these three amino acids are altered to their counterparts in Sts-1(PGM) has substantially increased activity. Our results suggest that the phosphatase activities of both suppressor of TCR signaling homologues cooperate in a similar but independent fashion to help set the threshold for TCR-induced T cell activation.
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Affiliation(s)
- Boris San Luis
- From the Departments of Molecular Genetics and Microbiology and
| | - Ben Sondgeroth
- Physiology and Biophysics, Stony Brook University, Stony Brook, New York 11794
| | - Nicolas Nassar
- Physiology and Biophysics, Stony Brook University, Stony Brook, New York 11794
| | - Nick Carpino
- From the Departments of Molecular Genetics and Microbiology and
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Weisheit S, Schäfer C, Mertens C, Berndt A, Liebmann C. PKCε acts as negative allosteric modulator of EGF receptor signalling. Cell Signal 2011; 23:436-48. [DOI: 10.1016/j.cellsig.2010.10.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 10/08/2010] [Accepted: 10/11/2010] [Indexed: 02/04/2023]
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Martínez-Florensa M, García-Blesa A, Yélamos J, Muñoz-Suano A, Domínguez-Villar M, Valdor R, Alonso A, García-Cózar F, Aparicio P, Malissen B, Aguado E. Serine residues in the LAT adaptor are essential for TCR-dependent signal transduction. J Leukoc Biol 2010; 89:63-73. [PMID: 20940326 DOI: 10.1189/jlb.0509342] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The adaptor protein LAT has a prominent role in the transduction of intracellular signals elicited by the TCR/CD3 complex. Upon TCR engagement, LAT becomes tyrosine-phosphorylated and thereby, recruits to the membrane several proteins implicated in the activation of downstream signaling pathways. However, little is known about the role of other conserved motifs present in the LAT sequence. Here, we report that the adaptor LAT contains several conserved serine-based motifs, which are essential for proper signal transduction through the TCR. Mutation of these serine motifs in the human T cell line Jurkat prevents proper calcium influx, MAPK activation, and IL-2 production in response to TCR/CD3 stimulation. Moreover, this mutant form of LAT has a reduced ability to bind to PLC-γ1 and SLP-76, although phosphorylation of tyrosine residues 132, 171, and 191 is not decreased, raising a possible role for the serine-based motifs of LAT for the binding of important partners. The functional role of LAT serine-based motifs in signal transduction could be mediated by an effect on tyrosine phosphorylation, as their mutation significantly diminishes the phosphorylation of tyrosine residue 226. In addition, these serine motifs seem to have a regulatory role, given that upon their mutation, ZAP-70 shows enhanced phosphorylation. Therefore, the LAT serine-based motifs likely regulate signaling pathways that are essential for T cell physiology.
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Affiliation(s)
- Mario Martínez-Florensa
- Departamento de Bioquimíca, Biología Molecular B e Inmunología, Facultad de Medicina, Universidad de Murcia, Murcia, Spain
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Xie Z, Chen Y, Pennypacker SD, Zhou Z, Peng D. The SH3 domain, but not the catalytic domain, is required for phospholipase C-gamma1 to mediate epidermal growth factor-induced mitogenesis. Biochem Biophys Res Commun 2010; 398:719-22. [PMID: 20621058 DOI: 10.1016/j.bbrc.2010.07.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Accepted: 07/02/2010] [Indexed: 11/17/2022]
Abstract
Phospholipase C-gamma1 (PLC-gamma1) is a multiple-domain protein and plays an important role in epidermal growth factor (EGF)-induced cell mitogenesis, but the underlying mechanism is unclear. We have previously demonstrated that PLC-gamma1 is required for EGF-induced mitogenesis of squamous cell carcinoma (SCC) cells, but the mitogenic function of PLC-gamma1 is independent of its lipase activity. Earlier studies suggest that the Src homology 3 (SH3) domain of PLC-gamma1 possesses mitogenic activity. In the present study, we sought to determine the role of the SH3 domain of PLC-gamma1 in EGF-induced SCC cell mitogenesis. We examined the effect of overexpression of PLC-gamma1, a catalytically active PLC-gamma1 mutant lacking the SH3 domain or a catalytically inactive PLC-gamma1 mutant lacking the X domain on EGF-induced SCC4 (tongue squamous cell carcinoma) cell mitogenesis. We found that overexpression of PLC-gamma1 enhanced EGF-induced SCC4 cell mitogenesis. This enhancement was abolished by deletion of the SH3 domain but not by deletion of the X catalytic domain. These data suggest that the SH3 domain, but not the catalytic domain, is required for PLC-gamma1 to mediate EGF-induced SCC4 cell mitogenesis.
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Affiliation(s)
- Zhongjian Xie
- Endocrine Unit, Veterans Affairs Medical Center, Northern California Institute for Research and Education, University of California, San Francisco, CA 94121, USA.
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Xie Z, Chen Y, Liao EY, Jiang Y, Liu FY, Pennypacker SD. Phospholipase C-gamma1 is required for the epidermal growth factor receptor-induced squamous cell carcinoma cell mitogenesis. Biochem Biophys Res Commun 2010; 397:296-300. [PMID: 20510673 DOI: 10.1016/j.bbrc.2010.05.103] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 05/21/2010] [Indexed: 11/17/2022]
Abstract
The epidermal growth factor receptor (EGFR) is a key driver in the process of squamous cell carcinoma (SCC) cell mitogenesis. Phospholipase C-gamma1 (PLC-gamma1) is a downstream target of EGFR signaling, but the role and necessity of PLC-gamma1 in EGFR-induced cell mitogenesis remain unclear. In the present study, we report an elevated expression of PLC-gamma1 in human SCC biopsies relative to adjacent normal epidermis, and in human SCC cell lines compared to normal human keratinocytes. EGFR-induced SCC cell mitogenesis was blocked by small interfering RNA knockdown of PLC-gamma1. However, inhibition of the catalytic activity of phospholipase C had no effect on EGFR-induced SCC cell mitogenesis. In response to the EGFR ligand epidermal growth factor (EGF), PLC-gamma1 was translocated not only to the plasma membrane but also to the nucleus. These data suggest that PLC-gamma1 is required for EGFR-induced SCC cell mitogenesis and the mitogenic function of PLC-gamma1 is independent of its lipase activity.
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Affiliation(s)
- Zhongjian Xie
- Endocrine Unit, Veterans Affairs Medical Center, Northern California Institute for Research and Education, University of California, San Francisco, CA 94121, USA.
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Lin D, Harris R, Stutzman R, Zampighi GA, Davidson H, Takemoto DJ. Protein Kinase C-γ Activation in the Early Streptozotocin Diabetic Rat Lens. Curr Eye Res 2009; 32:523-32. [PMID: 17612968 DOI: 10.1080/02713680701418124] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE The purpose of this study is to demonstrate the early activation of the protein kinase C-gamma (PKC-gamma) pathway in the streptozotocin (STZ)-induced diabetic rat lens. METHODS Twelve-week-old male and female Sprague-Dawley rats were injected with 80 mg/kg (body weight) of STZ (N-[methylnitrosocarbamoyl]-D-glucosamine) intraperitoneally. Very high glucose (VHG) diabetes was defined as a nonfasting blood glucose level of at least 450 mg/dl, confirmed by daily monitoring with Accu-Check Advantage test strips, and occurred about 2 weeks after STZ administration. All assayed lenses were from VHG or age-matched control rats, harvested within 24 hr of VHG detection. PKC-gamma activation was measured by enzyme activity assay and by Western blotting to show autophosphorylation on Thr514. Cellular insulin-like growth factor-1 (IGF-1), PKC-gamma phosphorylation of Cx43 on Ser368, and activation of phospholipase C-gamma 1 (PLC-gamma 1), extracellular signal-regulated kinase (ERK1/2), and caspase-3 were determined by Western blotting. Endogenous diacylglycerol (DAG) levels were measured with a DAG assay kit. Lens gap junction activity was determined by the microinjection/Lucifer yellow dye transfer assay. Electron microscopy was applied to affirm fiber cell damage in the VHG diabetic lenses. RESULTS In the lenses of VHG diabetic rats, PKC-gamma enzyme was activated. PKC-gamma could be further activated by 400 nM phorbol-12-myristate-13-acetate (PMA), but the PKC-gamma protein levels remained constant. No elevation of IGF-1 level was observed. Western blots showed that activation of PKC-gamma may be due to activation of PLC-gamma 1, which synthesized endogenous DAG, a native PKC activator. The level of PKC-gamma -catalyzed phosphorylation of Cx43 on Ser368 and resulting inhibition of lens gap junction dye transfer activity was increased in the VHG diabetic lenses. At this early time period, the diabetic lens showed no activation of either caspase-3 or ERK1/2. Only a single fiber cell layer deep within the cortex (approximately 90 cell layers from capsule surface) showed vacuoles and damaged cell connections. CONCLUSIONS Early activation of PLC-gamma 1 and elevated DAG were observed within VHG diabetic lenses. These were correlated with activation of PKC-gamma, phosphorylation of Cx43 on Ser368, and inhibition of dye transfer. Abnormal signaling from PKC-gamma to Cx43 in the epithelial cells/early fiber cells, observed within VHG diabetic lenses, may be responsible for fiber cell damage deeper in the lens cortex.
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Affiliation(s)
- Dingbo Lin
- Department of Biochemistry, Kansas State University, Manhattan, Kansas 66506, USA
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30
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Kim IH, Lee HY, Lee HD, Jung YJ, Tendler SJB, Williams PM, Allen S, Ryu SH, Park JW. Interactions between signal-transducing proteins measured by atomic force microscopy. Anal Chem 2009; 81:3276-84. [PMID: 19323535 DOI: 10.1021/ac8024366] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Atomic force microscopy (AFM) has been used to study the specific interactions between the signal-transducing proteins mammalian phospholipase D1 (PLD1), phospholipase C-gamma1 (PLC-gamma1), and Munc-18-1. To record the forces between them, the Phox homology (PX) domain of PLD1, the Src homology (SH3) domain of PLC-gamma1, and Munc-18-1 were fused with glutathione S-transferase (GST) and immobilized onto reduced glutathione (GSH)-tethered surfaces. In order to enhance the recognition efficiency and avoid undesirable complications, both AFM tips and substrates were first modified with dendrons of two different sizes. Under the employed conditions, the probability of observing an unbinding event increased, most force-distance curves showed the single rupture events, and the unbinding forces were 51 +/- 2 pN for PX-(Munc-18-1) and 42 +/- 2 pN for PX-SH3. To investigate dynamics of these biomolecular interactions, we measured the loading rate dependence of the unbinding forces. The unbinding forces increased linearly with the logarithm of the loading rate, indicating the presence of a single potential barrier in the dissociation energy landscape. The measured off-rate constants (k(off)) at 15 degrees C were 10(-3.4 +/- 0.3) s(-1) for PX-(Munc-18-1) and 10(-1.7 +/- 0.1) s(-1) for PX-SH3. Further, we elucidated the influence of free SH3 and Munc-18-1 on the specific PX-(Munc-18-1) and PX-SH3 interaction, respectively.
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Affiliation(s)
- Il Hong Kim
- National Core Research Center for Systems Bio-Dynamics, Department of Chemistry, Pohang University of Science and Technology, San 31 Hyoja-dong, Pohang, 790-784, Korea
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31
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Li S, Wang Q, Wang Y, Chen X, Wang Z. PLC-gamma1 and Rac1 coregulate EGF-induced cytoskeleton remodeling and cell migration. Mol Endocrinol 2009; 23:901-13. [PMID: 19264842 DOI: 10.1210/me.2008-0368] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
It is well established that epidermal growth factor (EGF) induces the cytoskeleton reorganization and cell migration through two major signaling cascades: phospholipase C-gamma1 (PLC-gamma1) and Rho GTPases. However, little is known about the cross talk between PLC-gamma1 and Rho GTPases. Here we showed that PLC-gamma1 forms a complex with Rac1 in response to EGF. This interaction is direct and mediated by PLC-gamma1 Src homology 3 (SH3) domain and Rac1 (106)PNTP(109) motif. This interaction is critical for EGF-induced Rac1 activation in vivo, and PLC-gamma1 SH3 domain is actually a potent and specific Rac1 guanine nucleotide exchange factor in vitro. We have also demonstrated that the interaction between PLC-gamma1 SH3 domain and Rac1 play a significant role in EGF-induced F-actin formation and cell migration. We conclude that PLC-gamma1 and Rac1 coregulate EGF-induced cell cytoskeleton remodeling and cell migration by a direct functional interaction.
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Affiliation(s)
- Siwei Li
- Department of Cell Biology, University of Alberta, Edmonton, Canada
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32
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Hu ZG, Chen Y, Zhou Q, Lv XY, Zhang Z, Wang YD, Xiao Y, Guo H, Liu YH, Tan RZ, Li QW, Bian GH, Wei YQ. Characterization of a novel Xenopus SH3 domain binding protein 5 like (xSH3BP5L) gene. Biochem Biophys Res Commun 2008; 365:214-220. [PMID: 17981148 DOI: 10.1016/j.bbrc.2007.10.146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Accepted: 10/20/2007] [Indexed: 05/25/2023]
Abstract
SH3 domain binding protein 5 like (xSH3BP5L) gene encodes a protein that is a new found member of SH3 domain binding protein family which has been implicated at multiple levels of biological functions. Here, we have characterized Xenopus SH3 domain binding protein 5 like (xSH3BP5L) gene in the development of Xenopus laevis. Transcripts of xSH3BP5L were detected at all stages of development and in numerous adult tissues. Whole-mount in situ hybridization demonstrated that xSH3BP5L is expressed at the animal pole from stage-2 onward. Interestingly, translational inhibition of xSH3BP5L using antisense morpholino oligonucleotides (MOs) and overexpression of xSH3BP5L in Xenopus embryos resulted in failed or delayed blastopore closure. Taken together, these data suggested that xSH3BP5L is required for normal embryogenesis of blastopore closure in X. laevis.
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Affiliation(s)
- Zhong-Guo Hu
- School of Life Science, and Core Facility of Gene Engineered Mouse, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Sichuan 610041, PR China
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Johnson MD, Sade B, Milano MT, Lee JH, Toms SA. New prospects for management and treatment of inoperable and recurrent skull base meningiomas. J Neurooncol 2007; 86:109-22. [PMID: 17624496 DOI: 10.1007/s11060-007-9434-z] [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] [Received: 03/16/2007] [Accepted: 06/07/2007] [Indexed: 12/25/2022]
Abstract
Skull base, including optic nerve, cavernous sinus, clival and foramen magnum tumors represent a major challenge for neurosurgeons and neuro-oncologists. Growth regulatory signaling pathways for these tumors are of increasing interest as potential targets for new chemotherapy. Those differentially activated in various grades of meningiomas are currently being identified as well. This article reviews some recent findings pathways that appear to regulate meningioma growth. Potential targets for novel therapies are also discussed.
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Affiliation(s)
- Mahlon D Johnson
- Department of Pathology and Laboratory Medicine, Division of Neuropathology, University of Rochester Medical Center, 601 Elmwood Ave. Box 626, Rochester, NY 14623, USA.
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34
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Su YC, Lu D, Tan XD, Dong AR, Tian HY, Luo SQ, Deng QK. Mathematical model of phosphatidylinositol-4,5-bisphosphate hydrolysis mediated by epidermal growth factor receptor generating diacylglycerol. J Biotechnol 2006; 124:574-91. [PMID: 16533541 DOI: 10.1016/j.jbiotec.2006.01.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 01/07/2006] [Accepted: 01/20/2006] [Indexed: 10/24/2022]
Abstract
Phosphatidylinositol-4,5-bisphosphate (PIP2) is hydrolyzed in response to the tyrosine phosphorylation of the epidermal growth factor receptor (EGFR) and plays an important role in regulating cell proliferation and differentiation through the generation of second messengers diacylglycerol (DAG) and trisphosphate inositol (IP3) which lead to the activation of protein kinase C (PKC) and increased levels of intracellular calcium, respectively. In the paper, a mathematical model was established to simulate the accumulation of DAG due to PIP2 hydrolysis mediated by EGFR. Molecular mechanisms between DAG, PIP2, EGFR and phosphatidylinositol transfer protein (PITP) were explained successfully, and positive cooperativity which existed between phospholipase C-gamma1 (PLC-gamma1) and PIP2 was also explained. In the model the effects of parameters on simulation of PIP2 hydrolysis were analyzed and the efficacies of some molecular intervention strategies were predicted. To test the coherence between the model and the biological response to epidermal growth factor (EGF) in cells, the levels of DAG and the tyrosine phosphorylation-EGFRs in NIH3T3 mouse embryonic fibroblast (MEF) were determined by biochemical experiments which showed that the accumulation of DAG was a sigmoidal function of phosphorylation-EGFR concentration, and the consistency between the mathematical model and experimental results was confirmed. In brief, this mathematical model provided a new idea for the further study of the dynamic change of biological characteristics in inositol phospholipid hydrolysis, predicting the efficacy of molecular intervention and the relationship between the metabolisms of inositol phospholipid and other signal transduction pathways.
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Affiliation(s)
- Yong-chun Su
- Department of Medical Physics, South Medical University, Guangzhou 510515, PR China
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35
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Mood K, Saucier C, Ishimura A, Bong YS, Lee HS, Park M, Daar IO. Oncogenic Met receptor induces cell-cycle progression in Xenopus oocytes independent of direct Grb2 and Shc binding or Mos synthesis, but requires phosphatidylinositol 3-kinase and Raf signaling. J Cell Physiol 2006; 207:271-85. [PMID: 16331688 DOI: 10.1002/jcp.20564] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Biological responses of hepatocyte growth factor (HGF) are mediated by the Met receptor tyrosine kinase. Although HGF is a potent mitogen for a variety of cells, the signals required for cell-cycle progression by the Met/HGF receptor are poorly defined. In this study, we have used the Xenopus oocyte system to define the role of various Met proximal-binding partners and downstream signaling pathways in cell-cycle regulation. We show that cell-cycle progression and activation of MAPK and JNK mediated by the oncogenic Met receptor, Tpr-Met, are dependent on its kinase activity and the presence of the twin phosphotyrosine (Y482 & Y489) residues in its C-terminus, but that the recruitment of Grb2 and Shc adaptor proteins is dispensable, implicating other signaling molecules. However, using Met receptor oncoproteins engineered to recruit specific signaling proteins, we demonstrate that recruitment of Grb2 or Shc adaptor proteins is sufficient to induce cell-cycle progression and activation of MAPK and JNK, while the binding of phospholipase-Cgamma or phosphatidylinositol 3-kinase alone fails to elicit these responses. Using various means to block phosphatidylinositol 3-kinase, phospholipase-Cgamma, MEK, JNK, Mos, and Raf1 activity, we show that unlike the fibroblast growth factor receptor, MEK-dependent and independent signaling contribute to Met receptor-mediated cell-cycle progression, but phospholipase-Cgamma or JNK activity and Mos synthesis are not critical. Notably, we demonstrate that Raf1 and phosphatidylinositol 3-kinase signaling are required for cell-cycle progression initiated by the Met receptor, a protein frequently deregulated in human tumors.
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Affiliation(s)
- Kathleen Mood
- Laboratory of Protein Dynamics and Signaling, National Cancer Institute-Frederick, Frederick, Maryland 21702, USA
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36
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Wang Y, Wu J, Wang Z. Akt binds to and phosphorylates phospholipase C-gamma1 in response to epidermal growth factor. Mol Biol Cell 2006; 17:2267-77. [PMID: 16525023 PMCID: PMC1446077 DOI: 10.1091/mbc.e05-10-0918] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Both phospholipase (PL) C-gamma1 and Akt (protein kinase B; PKB) are signaling proteins that play significant roles in the intracellular signaling mechanism used by receptor tyrosine kinases, including epidermal growth factor (EGF) receptor (EGFR). EGFR activates PLC-gamma1 directly and activates Akt indirectly through phosphatidylinositol 3-kinase (PI3K). Many studies have shown that the PLC-gamma1 pathway and PI3K-Akt pathway interact with each other. However, it is not known whether PLC-gamma1 binds to Akt directly. In this communication, we identified a novel interaction between PLC-gamma1 and Akt. We demonstrated that the interaction is mediated by the binding of PLC-gamma1 Src homology (SH) 3 domain to Akt proline-rich motifs. We also provide a novel model to depict how the interaction between PLC-gamma1 SH3 domain and Akt proline-rich motifs is dependent on EGF stimulation. In this model, phosphorylation of PLC-gamma1 Y783 by EGF causes the conformational change of PLC-gamma1 to allow the interaction of its SH3 domain with Akt proline-rich motifs. Furthermore, we showed that the interaction between PLC-gamma1 and Akt resulted in the phosphorylation of PLC-gamma1 S1248 by Akt. Finally, we showed that the interaction between PLC-gamma1 and Akt enhanced EGF-stimulated cell motility.
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Affiliation(s)
- Yi Wang
- Department of Cell Biology and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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Suzuki A, Ogura T, Esumi H. NDR2 acts as the upstream kinase of ARK5 during insulin-like growth factor-1 signaling. J Biol Chem 2006; 281:13915-21. [PMID: 16488889 DOI: 10.1074/jbc.m511354200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ARK5 is a tumor progression-associated factor that is directly phosphorylated by AKT at serine 600 in the regulatory domain, but phosphorylation at the conserved threonine residue on the active T loop has been found to be required for its full activation. In this study, we identified serine/threonine protein kinase NDR2 as a protein kinase that phosphorylates and activates ARK5 during insulin-like growth factor (IGF)-1 signaling. Upon stimulation with IGF-1, NDR2 was found to directly phosphorylate the conserved threonine 211 on the active T loop of ARK5 and to promote cell survival and invasion of colorectal cancer cell lines through ARK5. During IGF-1 signaling, phosphorylation at three residues (threonine 75, serine 282, and threonine 442) was also found to be required for NDR2 activation. Among these three residues, phosphorylation of serine 282 seemed to be the most important for NDR2 activation (the same as for the mouse homologue) because its aspartic acid-converted mutant (NDR2/S282D) induced ARK5-mediated cell survival and invasion activities even in the absence of IGF-1. As in the mouse homologue, threonine 75 in NDR2 was required for interaction with S100B, and binding was in a calcium ion- and phospholipase C-gamma-dependent manner. We also found that PDK-1 plays an important role in NDR2 activation especially in the phosphorylation of threonine 442. Based on the results of this study, we report here that NDR2 is an upstream kinase of ARK5 that plays an essential role in tumor progression through ARK5.
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Affiliation(s)
- Atsushi Suzuki
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
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Oliva JL, Griner EM, Kazanietz MG. PKC isozymes and diacylglycerol-regulated proteins as effectors of growth factor receptors. Growth Factors 2005; 23:245-52. [PMID: 16338787 DOI: 10.1080/08977190500366043] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Growth factors exert their cellular effects through signal transduction pathways that are initiated by the ligation of growth factors to their cell surface receptors. One of the well-established effectors of growth factor receptors is protein kinase C (PKC), a family of serine-threonine kinases that have been known for years as the main target of the phorbol ester tumor promoters. While there is abundant information regarding downstream PKC effectors and partners, how individual PKC isozymes become activated by growth factors and the regulation of receptor function by PKCs is only partially understood. Moreover, the identification of novel "non-kinase" DAG-binding proteins has added a new level of complexity to the field of DAG signaling.
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Affiliation(s)
- José Luis Oliva
- School of Medicine, University of Pennsylvania, Department of Pharmacology, Philadelphia, PA 19104-6160, USA
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Johnson M, Toms S. Mitogenic Signal Transduction Pathways in Meningiomas: Novel Targets for Meningioma Chemotherapy? J Neuropathol Exp Neurol 2005; 64:1029-36. [PMID: 16319713 DOI: 10.1097/01.jnen.0000189834.63951.81] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The roles of growth factor receptors and numerous downstream growth regulatory pathways are of increasing interest in neuro-oncology. These pathways have been extensively studied in gliomas but only recently analyzed in meningiomas. This article reviews current research on the growth factor receptor-Ras-Raf-1-MEK-1-MAPK, PI3K-Akt/PKB, PLC-gamma1-PKC, phospholipase A2-cyclooxygenase, and TGF-beta receptor-Smad pathways that appear to regulate meningioma growth and inhibit apoptosis. Sites along these receptor/kinase cascades that might be targeted by novel therapies are also discussed.
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Affiliation(s)
- Mahlon Johnson
- Department of Pathology, University of Tennessee, Graduate School of Medicine, Knoxville, Tennessee 37920, USA.
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40
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Liu Z, Li H, Derouet M, Filmus J, LaCasse EC, Korneluk RG, Kerbel RS, Rosen KV. ras Oncogene triggers up-regulation of cIAP2 and XIAP in intestinal epithelial cells: epidermal growth factor receptor-dependent and -independent mechanisms of ras-induced transformation. J Biol Chem 2005; 280:37383-92. [PMID: 16115895 DOI: 10.1074/jbc.m503724200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Detachment of normal epithelial cells from the extracellular matrix (ECM) triggers apoptosis, a phenomenon called anoikis. Conversely, carcinomas (cancers of epithelial origin) represent three-dimensional disorganized multicellular masses in which cells are deprived of adhesion to the ECM but remain viable. Resistance of cancer cells to anoikis is thought to be critical for tumor progression. However, the knowledge about molecular mechanisms of this type of resistance remains limited. Herein we report that ras oncogene, an established inhibitor of anoikis, triggers a significant upregulation of anti-apoptotic proteins cIAP2 and XIAP in intestinal epithelial cells. We also observed that the effect of ras on cIAP2 requires ras-induced autocrine production of transforming growth factor alpha (TGF-alpha), a ligand for epidermal growth factor receptor, whereas ras-triggered up-regulation of XIAP is TGF-alpha-independent. Moreover, overexpression of either cIAP2 or XIAP in nonmalignant intestinal epithelial cell was found to block anoikis. In addition, an established IAP antagonist Smac or Smac-derived cell-permeable peptide suppressed ras-induced anoikis resistance and subsequent anchorage-independent growth of ras-transformed cells. We conclude that ras-induced overexpression of cIAP2 and XIAP significantly contributes to the ability of ras-transformed intestinal epithelial cells to survive in the absence of adhesion to the ECM and grow in a three-dimensional manner.
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Affiliation(s)
- Zaiping Liu
- Department of Pediatrics, Atlantic Research Centre, Dalhousie University, Halifax, Nova Scotia, Canada
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41
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Mawrin C, Sasse T, Kirches E, Kropf S, Schneider T, Grimm C, Pambor C, Vorwerk CK, Firsching R, Lendeckel U, Dietzmann K. Different Activation of Mitogen-Activated Protein Kinase and Akt Signaling Is Associated with Aggressive Phenotype of Human Meningiomas. Clin Cancer Res 2005; 11:4074-82. [PMID: 15930342 DOI: 10.1158/1078-0432.ccr-04-2550] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Activation of intracellular signaling cascades has been implicated in the growth control of benign meningiomas, but their role for meningioma progression and outcome is unknown. Here we determined the expression and function of proteins involved in mitogen-activated protein kinase (MAPK) and phosphinositol-3 kinase (PI3K)/Akt signaling in benign, atypical, and malignant meningiomas and studied their association with clinicopathologic data including meningioma recurrence. EXPERIMENTAL DESIGN Expression of various MAPK and PI3K signaling proteins was determined in 70 primary meningiomas and, if present, in recurrent tumors by immunohistochemistry and Western blotting. The expression patterns in primary and recurrent tumors were related to clinical data. The effect of MAPK and PI3K pathway inhibition on cell proliferation and apoptosis was determined using a primary malignant meningioma cell culture. RESULTS Atypical and malignant meningiomas showed higher levels of phospho-Akt compared with benign tumors, and their proliferation could be inhibited by PI3K blocking using wortmannin. PI3K inhibition did not induce apoptosis in malignant meningioma cells. In contrast, expression of phospho-Raf and phospho-MAPK was decreased in aggressive meningiomas compared with benign tumors, but MAPK inhibition by PD98059 resulted in tumor cell apoptosis and decreased proliferation. Reduced MAPK activation was associated with meningioma recurrence, and PI3K activation was associated with poor preclinical condition and brain invasion of malignant meningiomas. CONCLUSIONS Both MAPK and PI3K/Akt pathways are activated at different levels in benign and malignant meningiomas. Activation of PI3K/Akt signaling contributes to the aggressive behavior of malignant meningiomas, whereas MAPK activation is involved in both proliferation and apoptosis of malignant meningiomas.
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Affiliation(s)
- Christian Mawrin
- Department of Neuropathology, Otto-von-Guericke University, Magdeburg, Germany.
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42
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Nishi M, Werner ED, Oh BC, Frantz JD, Dhe-Paganon S, Hansen L, Lee J, Shoelson SE. Kinase activation through dimerization by human SH2-B. Mol Cell Biol 2005; 25:2607-21. [PMID: 15767667 PMCID: PMC1061652 DOI: 10.1128/mcb.25.7.2607-2621.2005] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The isoforms of SH2-B, APS, and Lnk form a family of signaling proteins that have been described as activators, mediators, or inhibitors of cytokine and growth factor signaling. We now show that the three alternatively spliced isoforms of human SH2-B readily homodimerize in yeast two-hybrid and cellular transfections assays, and this is mediated specifically by a unique domain in its amino terminus. Consistent with previous reports, we further show that the SH2 domains of SH2-B and APS bind JAK2 at Tyr813. These findings suggested a model in which two molecules of SH2-B or APS homodimerize with their SH2 domains bound to two JAK2 molecules, creating heterotetrameric JAK2-(SH2-B)2-JAK2 or JAK2-(APS)2-JAK2 complexes. We further show that APS and SH2-B isoforms heterodimerize. At lower levels of SH2-B or APS expression, dimerization approximates two JAK2 molecules to induce transactivation. At higher relative concentrations of SH2-B or APS, kinase activation is blocked. SH2-B or APS homodimerization and SH2-B/APS heterodimerization thus provide direct mechanisms for activating and inhibiting JAK2 and other kinases from the inside of the cell and for potentiating or attenuating cytokine and growth factor receptor signaling when ligands are present.
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Affiliation(s)
- Masahiro Nishi
- Joslin Diabetes Center, One Joslin Place, Boston, MA 02215, USA
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43
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Athale C, Mansury Y, Deisboeck TS. Simulating the impact of a molecular 'decision-process' on cellular phenotype and multicellular patterns in brain tumors. J Theor Biol 2004; 233:469-81. [PMID: 15748909 DOI: 10.1016/j.jtbi.2004.10.019] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2004] [Accepted: 10/14/2004] [Indexed: 11/30/2022]
Abstract
Experimental evidence indicates that human brain cancer cells proliferate or migrate, yet do not display both phenotypes at the same time. Here, we present a novel computational model simulating this cellular decision-process leading up to either phenotype based on a molecular interaction network of genes and proteins. The model's regulatory network consists of the epidermal growth factor receptor (EGFR), its ligand transforming growth factor-alpha (TGF alpha), the downstream enzyme phospholipaseC-gamma (PLC gamma) and a mitosis-associated response pathway. This network is activated by autocrine TGF alpha secretion, and the EGFR-dependent downstream signaling this step triggers, as well as modulated by an extrinsic nutritive glucose gradient. Employing a framework of mass action kinetics within a multiscale agent-based environment, we analyse both the emergent multicellular behavior of tumor growth and the single-cell molecular profiles that change over time and space. Our results show that one can indeed simulate the dichotomy between cell migration and proliferation based solely on an EGFR decision network. It turns out that these behavioral decisions on the single cell level impact the spatial dynamics of the entire cancerous system. Furthermore, the simulation results yield intriguing experimentally testable hypotheses also on the sub-cellular level such as spatial cytosolic polarization of PLC gamma towards an extrinsic chemotactic gradient. Implications of these results for future works, both on the modeling and experimental side are discussed.
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Affiliation(s)
- Chaitanya Athale
- Complex Biosystems Modeling Laboratory, Harvard-MIT (HST) Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA
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Chan SM, Ermann J, Su L, Fathman CG, Utz PJ. Protein microarrays for multiplex analysis of signal transduction pathways. Nat Med 2004; 10:1390-6. [PMID: 15558056 DOI: 10.1038/nm1139] [Citation(s) in RCA: 168] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2004] [Accepted: 07/29/2004] [Indexed: 02/02/2023]
Abstract
We have developed a multiplexed reverse phase protein (RPP) microarray platform for simultaneous monitoring of site-specific phosphorylation of numerous signaling proteins using nanogram amounts of lysates derived from stimulated living cells. We first show the application of RPP microarrays to the study of signaling kinetics and pathway delineation in Jurkat T lymphocytes. RPP microarrays were used to profile the phosphorylation state of 62 signaling components in Jurkat T cells stimulated through their membrane CD3 and CD28 receptors, identifying a previously unrecognized link between CD3 crosslinking and dephosphorylation of Raf-1 at Ser259. Finally, the potential of this technology to analyze rare primary cell populations is shown in a study of differential STAT protein phosphorylation in interleukin (IL)-2-stimulated CD4(+)CD25(+) regulatory T cells. RPP microarrays, prepared using simple procedures and standard microarray equipment, represent a powerful new tool for the study of signal transduction in both health and disease.
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Affiliation(s)
- Steven M Chan
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
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45
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Runft LL, Carroll DJ, Gillett J, Giusti AF, O'Neill FJ, Foltz KR. Identification of a starfish egg PLC-gamma that regulates Ca2+ release at fertilization. Dev Biol 2004; 269:220-36. [PMID: 15081369 DOI: 10.1016/j.ydbio.2004.01.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2003] [Revised: 01/23/2004] [Accepted: 01/27/2004] [Indexed: 10/26/2022]
Abstract
At fertilization, eggs undergo a cytoplasmic free Ca2+ rise, which is necessary for stimulating embryogenesis. In starfish eggs, studies using inhibitors designed against vertebrate proteins have shown that this Ca2+ rise requires an egg Src family kinase (SFK) that directly or indirectly activates phospholipase C-gamma (PLC-gamma) to produce IP3, which triggers Ca2+ release from the egg's endoplasmic reticulum (ER) [reviewed in Semin. Cell Dev. Biol. 12 (2001) 45]. To examine in more detail the endogenous factors in starfish eggs that are required for Ca2+ release at fertilization, an oocyte cDNA encoding PLC-gamma was isolated from the starfish Asterina miniata. This cDNA, designated AmPLC-gamma, encodes a protein with 49% identity to mammalian PLC-gamma1. A 58-kDa Src family kinase interacted with recombinant AmPLC-gamma Src homology 2 (SH2) domains in a specific, fertilization-responsive manner. Immunoprecipitations of sea urchin egg PLC-gamma using an affinity-purified antibody directed against AmPLC-gamma revealed fertilization-dependent phosphorylation of PLC-gamma. Injecting starfish eggs with the tandem SH2 domains of AmPLC-gamma (which inhibits PLC-gamma activation) specifically inhibited Ca2+ release at fertilization. These results indicate that an endogenous starfish egg PLC-gamma interacts with an egg SFK and mediates Ca2+ release at fertilization via a PLC-gamma SH2 domain-mediated mechanism.
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Affiliation(s)
- Linda L Runft
- Department of Molecular, Cellular & Developmental Biology and the Marine Science Institute, University of California-Santa Barbara, Santa Barbara, CA 93106-9610, USA
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46
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Chandrasekher G, Sailaja D. Alterations in lens protein tyrosine phosphorylation and phosphatidylinositol 3-kinase signaling during selenite cataract formation. Curr Eye Res 2004; 28:135-44. [PMID: 14972719 DOI: 10.1076/ceyr.28.2.135.26232] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE Protein tyrosine phosphorylation is an important event in the cell signal transduction process. Phosphatidylinositol-3 kinase (PI-3K) is an intracellular signal mediator and plays a key role in many cellular functions. In this study we have examined the changes in lens protein tyrosine phosphorylation and its impact on phosphatidylinositol 3-kinase (PI-3K) signaling during selenite cataract development. METHODS Cataract was induced in 10 days old rat pups by a single sub-cutaneous injection of sodium selenite (30 microM/Kg body weight) and lenses were collected at different stages of cataract development. Immunoprecipitation and Western immunoblotting were employed to determine protein tyrosine phosphorylation, PI-3K activity and protein in lens cell extracts. Tyrosine kinase activity in lens membrane preparations was assayed in the presence of a synthetic substrate peptide and [32P]ATP. RESULTS Protein tyrosine phosphorylation in the lens was disrupted before the onset of cataract. A decrease in tyrosine phosphorylation of lens proteins was observed within 2-3 days of selenite injection (pre-cataract stage). The effect was much more prominent with the progression of cataract. The decrease in protein tyrosine phosphorylation correlated with the decrease in tyrosine kinase activity associated with the lens membrane fraction. Stimulation of normal rat lenses in organ culture with insulin and IGF-1 caused an increase in the phosphorylation of proteins, whose tyrosine phosphorylation status appeared to be diminished during cataract development. Insulin and IGF-1 also stimulated rat lens PI-3K activity. While there was no change in total PI-3K activity during the onset of cataract, the activity of PI-3K associated with tyrosine phosphorylated proteins decreased markedly in pre-cataract lenses. Further, the ability of IGF-1 to stimulate PI-3K activity was significantly reduced in lens epithelial cells treated with selenium. CONCLUSIONS These studies show that signaling events involving the protein tyrosine phosphorylation process and activation of PI-3K are altered during selenite cataract formation and implicate defects in signal transduction mechanisms as contributing factors in the development of cataract.
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Affiliation(s)
- Gudiseva Chandrasekher
- Department of Ophthalmology and Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA.
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47
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Abstract
Phosphoinositide (PI) 3-kinase enhancer (PIKE) is a brain-specific GTPase that binds to PI 3-kinase and stimulates its lipid kinase activity. It exists in two forms: the first to be identified, PIKE-S, is shorter and exclusively nuclear; by contrast, the longer form, PIKE-L, resides in multiple intracellular compartments. Nerve growth factor treatment leads to PIKE-S activation by triggering the nuclear translocation of phospholipase C (PLC)-γ1, which acts as a physiological guanine nucleotide exchange factor (GEF) for PIKE-S through its Src-homlogy 3 (SH3) domain. Cytoplasmic PI 3-kinase and its lipid product phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P3] regulate the membrane translocation and activation of many signaling molecules by binding to their pleckstrin homology (PH) domains. However, little is known about the physiological roles of their nuclear counterparts. The nuclear PLC-γ1/PIKE-S/PI 3-kinase signaling pathway seems to be an extension of the crosstalk between cytoplasmic PLC-γ1 and PI 3-kinase. PIKE-L contains a C-terminal extension consisting of an ADP ribosylation-GTPase-activating protein (ArfGAP) domain and two ankyrin repeats in addition to the N-terminal GTPase domain. PIKE-L could have additional, extranuclear functions, including regulation of postsynaptic signaling by metabotropic glutamate receptors.
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Affiliation(s)
- Keqiang Ye
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA.
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48
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Wang Y, Wang Z. Regulation of EGF-induced phospholipase C-gamma1 translocation and activation by its SH2 and PH domains. Traffic 2003; 4:618-30. [PMID: 12911816 DOI: 10.1034/j.1600-0854.2003.00121.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Translocation of phospholipase C-gamma1 is essential for its function in response to growth factors. However, in spite of recent progress, the phospholipase C-gamma1 translocation pattern and the molecular mechanism of the translocation are far from fully understood. Contradictory results were reported as to which domain, PH or SH2, controls the epidermal growth factor-induced translocation of phospholipase C-gamma1. In this communication, we studied epidermal growth factor-induced translocation of phospholipase C-gamma1 by using comprehensive approaches including biochemistry, indirect fluorescence and live fluorescence imaging. We provided original evidence demonstrating that: (i) endogenous phospholipase C-gamma1, similar to YFP-tagged phospholipase C-gamma1, translocated to endosomes following its initial translocation from cytosol to the plasma membrane in response to epidermal growth factor; (ii) phospholipase C-gamma1 remained phosphorylated in endosomes, but phospholipase C-gamma1 activity is not required for its translocation, which suggests a signaling role for phospholipase C-gamma1 in endosomes; (iii) the PH domain was not required for the initial translocation of phospholipase C-gamma1 from cytosol to the plasma membrane, but it stabilizes phospholipase C-gamma1 in the membrane at a later time; (iv) the function of the phospholipase C-gamma1 PH domain in stabilizing phospholipase C-gamma1 membrane association is very important in maintaining the activity of phospholipase C-gamma1; and (v) the role of the PH domain in phospholipase C-gamma1 membrane association and activation is dependent on PI3K activity. We conclude that the phospholipase C-gamma1 SH2 and PH domains coordinate to determine epidermal growth factor-induced translocation and activation of phospholipase C-gamma1.
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Affiliation(s)
- Yi Wang
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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Liu JJ, Hartman DS, Bostwick JR. An immobilized metal ion affinity adsorption and scintillation proximity assay for receptor-stimulated phosphoinositide hydrolysis. Anal Biochem 2003; 318:91-9. [PMID: 12782036 DOI: 10.1016/s0003-2697(03)00159-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A novel approach to measuring receptor-stimulated phosphoinositide hydrolysis was developed based on the principles of immobilized metal ion affinity chromatography (IMAC) and scintillation proximity assay (SPA). Hard Lewis metal ions, such as Zr(4+), Ga(3+), Al(3+), Fe(3+), Lu(3+), and Sc(3+), were immobilized on SPA beads via metal chelate and utilized as affinity ligands to entrap inositol phosphates. [3H]Inositol phosphates bound to IMAC-SPA beads through the strong interaction of their phosphate group with the immobilized metal ions. The binding brought [3H]inositol phosphates in close proximity to the scintillant embedded in the SPA beads, thereby allowing the radioactivity to be quantified. Quantification of [3H]inositol phosphate production in cells preincubated with [3H]inositol provided a highly sensitive measurement of phosphoinositide hydrolysis. The utility of this approach was demonstrated in measuring the response mediated by the G-protein-coupled neurokinin NK1 receptor and the tyrosine kinase-linked platelet-derived growth factor (PDGF) receptor. Substance P stimulated phosphoinositide hydrolysis concentration-dependently in CHO cells expressing NK1 receptors with a maximal 12-fold increase in inositol phosphate production. Similarly, PDGF-BB stimulated a 5-fold increase in phosphoinositide hydrolysis in quiescent Swiss 3T3 cells. This new approach is highly sensitive, fast, simple, easily performed on 96-well plates, and amenable for high-throughput screening.
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Affiliation(s)
- Jay Jie Liu
- Lead Discovery Department, AstraZeneca Pharmaceuticals LP, Wilmington, DE 19850, USA.
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Jang IH, Lee S, Park JB, Kim JH, Lee CS, Hur EM, Kim IS, Kim KT, Yagisawa H, Suh PG, Ryu SH. The direct interaction of phospholipase C-gamma 1 with phospholipase D2 is important for epidermal growth factor signaling. J Biol Chem 2003; 278:18184-90. [PMID: 12646582 DOI: 10.1074/jbc.m208438200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epidermal growth factor (EGF) receptor has an important role in cellular proliferation, and the enzymatic activity of phospholipase C (PLC)-gamma1 is regarded to be critical for EGF-induced mitogenesis. In this study, we report for the first time a phospholipase complex composed of PLC-gamma1 and phospholipase D2 (PLD2). PLC-gamma1 is co-immunoprecipitated with PLD2 in COS-7 cells. The results of in vitro binding analysis and co-immunoprecipitation analysis in COS-7 cells show that the Src homology (SH) 3 domain of PLC-gamma1 binds to the proline-rich motif within the Phox homology (PX) domain of PLD2. The interaction between PLC-gamma1 and PLD2 is EGF stimulation-dependent and potentiates EGF-induced inositol 1,4,5-trisphosphate (IP(3)) formation and Ca(2+) increase. Mutating Pro-145 and Pro-148 within the PX domain of PLD2 to leucines disrupts the interaction between PLC-gamma1 and PLD2 and fails to potentiate EGF-induced IP(3) formation and Ca(2+) increase. However, neither PLD2 wild type nor PLD2 mutant affects the EGF-induced tyrosine phosphorylation of PLC-gamma1. These findings suggest that, upon EGF stimulation, PLC-gamma1 directly interacts with PLD2 and this interaction is important for PLC-gamma1 activity.
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Affiliation(s)
- Il Ho Jang
- Department of Life Science and Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea
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