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Griffin EN, Jucius T, Sim SE, Harris BS, Heinz S, Ackerman SL. RREB1 regulates neuronal proteostasis and the microtubule network. SCIENCE ADVANCES 2024; 10:eadh3929. [PMID: 38198538 PMCID: PMC10780896 DOI: 10.1126/sciadv.adh3929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 12/12/2023] [Indexed: 01/12/2024]
Abstract
Transcription factors play vital roles in neuron development; however, little is known about the role of these proteins in maintaining neuronal homeostasis. Here, we show that the transcription factor RREB1 (Ras-responsive element-binding protein 1) is essential for neuron survival in the mammalian brain. A spontaneous mouse mutation causing loss of a nervous system-enriched Rreb1 transcript is associated with progressive loss of cerebellar Purkinje cells and ataxia. Analysis of chromatin immunoprecipitation and sequencing, along with RNA sequencing data revealed dysregulation of RREB1 targets associated with the microtubule cytoskeleton. In agreement with the known role of microtubules in dendritic development, dendritic complexity was disrupted in Rreb1-deficient neurons. Analysis of sequencing data also suggested that RREB1 plays a role in the endomembrane system. Mutant Purkinje cells had fewer numbers of autophagosomes and lysosomes and contained P62- and ubiquitin-positive inclusions. Together, these studies demonstrate that RREB1 functions to maintain the microtubule network and proteostasis in mammalian neurons.
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Affiliation(s)
- Emily N. Griffin
- Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Thomas Jucius
- Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Su-Eon Sim
- Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
| | | | - Sven Heinz
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Susan L. Ackerman
- Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
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2
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Martin-Salgado M, Ochoa-Echeverría A, Mérida I. Diacylglycerol kinases: A look into the future of immunotherapy. Adv Biol Regul 2024; 91:100999. [PMID: 37949728 DOI: 10.1016/j.jbior.2023.100999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 11/01/2023] [Indexed: 11/12/2023]
Abstract
Cancer still represents the second leading cause of death right after cardiovascular diseases. According to the World Health Organization (WHO), cancer provoked around 10 million deaths in 2020, with lung and colon tumors accounting for the deadliest forms of cancer. As tumor cells become resistant to traditional therapeutic approaches, immunotherapy has emerged as a novel strategy for tumor control. T lymphocytes are key players in immune responses against tumors. Immunosurveillance allows identification, targeting and later killing of cancerous cells. Nevertheless, tumors evolve through different strategies to evade the immune response and spread in a process called metastasis. The ineffectiveness of traditional strategies to control tumor growth and expansion has led to novel approaches considering modulation of T cell activation and effector functions. Program death receptor 1 (PD-1) and cytotoxic T-lymphocyte antigen 4 (CTLA-4) showed promising results in the early 90s and nowadays are still being exploited together with other drugs for several cancer types. Other negative regulators of T cell activation are diacylglycerol kinases (DGKs) a family of enzymes that catalyze the conversion of diacylglycerol (DAG) into phosphatidic acid (PA). In T cells, DGKα and DGKζ limit the PLCγ/Ras/ERK axis thus attenuating DAG mediated signaling and T cell effector functions. Upregulation of either of both isoforms results in impaired Ras activation and anergy induction, whereas germline knockdown mice showed enhanced antitumor properties and more effective immune responses against pathogens. Here we review the mechanisms used by DGKs to ameliorate T cell activation and how inhibition could be used to reinvigorate T cell functions in cancer context. A better knowledge of the molecular mechanisms involved upon T cell activation will help to improve current therapies with DAG promoting agents.
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Affiliation(s)
- Miguel Martin-Salgado
- Department of Immunology and Oncology. National Centre for Biotechnology. Spanish Research Council (CNB-CSIC), Spain
| | - Ane Ochoa-Echeverría
- Department of Immunology and Oncology. National Centre for Biotechnology. Spanish Research Council (CNB-CSIC), Spain
| | - Isabel Mérida
- Department of Immunology and Oncology. National Centre for Biotechnology. Spanish Research Council (CNB-CSIC), Spain.
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3
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Liu D, Zinski A, Mishra A, Noh H, Park GH, Qin Y, Olorife O, Park JM, Abani CP, Park JS, Fung J, Sawaqed F, Coyle JT, Stahl E, Bendl J, Fullard JF, Roussos P, Zhang X, Stanton PK, Yin C, Huang W, Kim HY, Won H, Cho JH, Chung S. Impact of schizophrenia GWAS loci converge onto distinct pathways in cortical interneurons vs glutamatergic neurons during development. Mol Psychiatry 2022; 27:4218-4233. [PMID: 35701597 DOI: 10.1038/s41380-022-01654-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 05/24/2022] [Accepted: 05/31/2022] [Indexed: 02/07/2023]
Abstract
Remarkable advances have been made in schizophrenia (SCZ) GWAS, but gleaning biological insight from these loci is challenging. Genetic influences on gene expression (e.g., eQTLs) are cell type-specific, but most studies that attempt to clarify GWAS loci's influence on gene expression have employed tissues with mixed cell compositions that can obscure cell-specific effects. Furthermore, enriched SCZ heritability in the fetal brain underscores the need to study the impact of SCZ risk loci in specific developing neurons. MGE-derived cortical interneurons (cINs) are consistently affected in SCZ brains and show enriched SCZ heritability in human fetal brains. We identified SCZ GWAS risk genes that are dysregulated in iPSC-derived homogeneous populations of developing SCZ cINs. These SCZ GWAS loci differential expression (DE) genes converge on the PKC pathway. Their disruption results in PKC hyperactivity in developing cINs, leading to arborization deficits. We show that the fine-mapped GWAS locus in the ATP2A2 gene of the PKC pathway harbors enhancer marks by ATACseq and ChIPseq, and regulates ATP2A2 expression. We also generated developing glutamatergic neurons (GNs), another population with enriched SCZ heritability, and confirmed their functionality after transplantation into the mouse brain. Then, we identified SCZ GWAS risk genes that are dysregulated in developing SCZ GNs. GN-specific SCZ GWAS loci DE genes converge on the ion transporter pathway, distinct from those for cINs. Disruption of the pathway gene CACNA1D resulted in deficits of Ca2+ currents in developing GNs, suggesting compromised neuronal function by GWAS loci pathway deficits during development. This study allows us to identify cell type-specific and developmental stage-specific mechanisms of SCZ risk gene function, and may aid in identifying mechanism-based novel therapeutic targets.
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Affiliation(s)
- Dongxin Liu
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA.
- Department of Developmental Cell Biology, Key Laboratory of Cell Biology, Ministry of Public Health, and Key Laboratory of Medical Cell Biology, Ministry of Education, China Medical University, Shenyang, China.
| | - Amy Zinski
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Akanksha Mishra
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Haneul Noh
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
- Department of Psychiatry, McLean Hospital/Harvard Medical School, Belmont, MA, 02478, USA
| | - Gun-Hoo Park
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Yiren Qin
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Oshoname Olorife
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - James M Park
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Chiderah P Abani
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Joy S Park
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Janice Fung
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Farah Sawaqed
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Joseph T Coyle
- Department of Psychiatry, McLean Hospital/Harvard Medical School, Belmont, MA, 02478, USA
| | - Eli Stahl
- Pamela Sklar Division of Psychiatric Genomics, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
| | - Jaroslav Bendl
- Pamela Sklar Division of Psychiatric Genomics, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
| | - John F Fullard
- Pamela Sklar Division of Psychiatric Genomics, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
| | - Panos Roussos
- Pamela Sklar Division of Psychiatric Genomics, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY, 10029, USA
- Mental Illness Research Education and Clinical Center (VISN 2 South), James J. Peters VA Medical Center, Bronx, NY, 10468, USA
| | - Xiaolei Zhang
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Patric K Stanton
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Changhong Yin
- Department of Pathology, New York Medical College, Valhalla, NY, 10595, USA
| | - Weihua Huang
- Department of Pathology, New York Medical College, Valhalla, NY, 10595, USA
| | - Hae-Young Kim
- Department of Public Health, New York Medical College, Valhalla, NY, USA
| | - Hyejung Won
- Department of Genetics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Jun-Hyeong Cho
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA
| | - Sangmi Chung
- Department of Cell biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA.
- Department of Psychiatry, McLean Hospital/Harvard Medical School, Belmont, MA, 02478, USA.
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4
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Barber CN, Goldschmidt HL, Ma Q, Devine LR, Cole RN, Huganir RL, Raben DM. Identification of Synaptic DGKθ Interactors That Stimulate DGKθ Activity. Front Synaptic Neurosci 2022; 14:855673. [PMID: 35573662 PMCID: PMC9095502 DOI: 10.3389/fnsyn.2022.855673] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 03/16/2022] [Indexed: 01/16/2023] Open
Abstract
Lipids and their metabolic enzymes are a critical point of regulation for the membrane curvature required to induce membrane fusion during synaptic vesicle recycling. One such enzyme is diacylglycerol kinase θ (DGKθ), which produces phosphatidic acid (PtdOH) that generates negative membrane curvature. Synapses lacking DGKθ have significantly slower rates of endocytosis, implicating DGKθ as an endocytic regulator. Importantly, DGKθ kinase activity is required for this function. However, protein regulators of DGKθ's kinase activity in neurons have never been identified. In this study, we employed APEX2 proximity labeling and mass spectrometry to identify endogenous interactors of DGKθ in neurons and assayed their ability to modulate its kinase activity. Seven endogenous DGKθ interactors were identified and notably, synaptotagmin-1 (Syt1) increased DGKθ kinase activity 10-fold. This study is the first to validate endogenous DGKθ interactors at the mammalian synapse and suggests a coordinated role between DGKθ-produced PtdOH and Syt1 in synaptic vesicle recycling.
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Affiliation(s)
- Casey N. Barber
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Hana L. Goldschmidt
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Qianqian Ma
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Lauren R. Devine
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Robert N. Cole
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Richard L. Huganir
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Daniel M. Raben
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States,*Correspondence: Daniel M. Raben,
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5
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Aslam N, Alvi F. TRPC3 Channel Activity and Viability of Purkinje Neurons can be Regulated by a Local Signalosome. Front Mol Biosci 2022; 9:818682. [PMID: 35265671 PMCID: PMC8899209 DOI: 10.3389/fmolb.2022.818682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/03/2022] [Indexed: 11/19/2022] Open
Abstract
Canonical transient receptor potential channels (TRPC3) may play a pivotal role in the development and viability of dendritic arbor in Purkinje neurons. This is a novel postsynaptic channel for glutamatergic synaptic transmission. In the cerebellum, TRPC3 appears to regulate functions relating to motor coordination in a highly specific manner. Gain of TRPC3 function is linked to significant alterations in the density and connectivity of dendritic arbor in Purkinje neurons. TRPC3 signals downstream of class I metabotropic glutamate receptors (mGluR1). Moreover, diacylglycerol (DAG) can directly bind and activate TRPC3 molecules. Here, we investigate a key question: How can the activity of the TRPC3 channel be regulated in Purkinje neurons? We also explore how mGluR1 activation, Ca2+ influx, and DAG homeostasis in Purkinje neurons can be linked to TRPC3 activity modulation. Through systems biology approach, we show that TRPC3 activity can be modulated by a Purkinje cell (PC)–specific local signalosome. The assembly of this signalosome is coordinated by DAG generation after mGluR1 activation. Our results also suggest that purinergic receptor activation leads to the spatial and temporal organization of the TRPC3 signaling module and integration of its key effector molecules such as DAG, PKCγ, DGKγ, and Ca2+ into an organized local signalosome. This signaling machine can regulate the TRPC3 cycling between active, inactive, and desensitized states. Precise activity of the TRPC3 channel is essential for tightly regulating the Ca2+ entry into PCs and thus the balance of lipid and Ca2+ signaling in Purkinje neurons and hence their viability. Cell-type–specific understanding of mechanisms regulating TRPC3 channel activity could be key in identifying therapeutic targeting opportunities.
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Affiliation(s)
- Naveed Aslam
- BioSystOmics, Houston, TX, United States
- *Correspondence: Naveed Aslam,
| | - Farah Alvi
- BioSystOmics, Houston, TX, United States
- Department of Physics, COMSATS University Islamabad, Lahore Campus, Pakistan
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Diacylglycerol kinase α inhibition cooperates with PD-1-targeted therapies to restore the T cell activation program. Cancer Immunol Immunother 2021; 70:3277-3289. [PMID: 33837851 DOI: 10.1007/s00262-021-02924-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 03/22/2021] [Indexed: 12/19/2022]
Abstract
BACKGROUND Antibody-based therapies blocking the programmed cell death-1/ligand-1 (PD-1/PD-L1) axis have provided unprecedent clinical success in cancer treatment. Acquired resistance, however, frequently occurs, commonly associated with the upregulation of additional inhibitory molecules. Diacylglycerol kinase (DGK) α limits the extent of Ras activation in response to antigen recognition, and its upregulation facilitates hypofunctional, exhausted T cell states. Pharmacological DGKα targeting restores cytotoxic function of chimeric antigen receptor and CD8+ T cells isolated from solid tumors, suggesting a mechanism to reverse T cell exhausted phenotypes. Nevertheless, the contribution of DGKα downstream of the PD-1/PD-L1 inhibitory axis in human T cells and the consequences of combining DGKα and anti-PD-1/PD-L1 inhibitors are still unresolved relevant issues. MATERIALS AND METHODS We used a human triple parameter reporter cell line to investigate DGKα contribution to the PD-1/PD-L1 inhibitory pathway. We also addressed the impact of deleting DGKα expression in the growth dynamics and systemic tumor-derived effects of a PD-1-related tumor model, the MC38 colon adenocarcinoma. RESULTS We identify DGKα as a contributor to the PD-1/PD-L1 axis that strongly limits the Ras/ERK/AP-1 pathway. DGKα function reinforces exhausted T cell phenotypes ultimately promoting tumor growth and generalized immunosuppression. Pharmacological DGKα inhibition selectively enhances AP-1 transcription and, importantly, cooperates with antibodies blocking the PD-1/PD-L1 interrelation. CONCLUSIONS Our results indicate that DGKα inhibition could provide an important mechanism to revert exhausted T lymphocyte phenotypes and thus favor proper anti-tumor T cell responses. The cooperative effect observed after PD-1/PD-L1 and DGKα blockade offers a promising strategy to improve the efficacy of immunotherapy in the treatment of cancer.
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7
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Diacylglycerol kinase ζ is a negative regulator of GPVI-mediated platelet activation. Blood Adv 2020; 3:1154-1166. [PMID: 30967391 DOI: 10.1182/bloodadvances.2018026328] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 03/08/2019] [Indexed: 02/07/2023] Open
Abstract
Diacylglycerol kinases (DGKs) are a family of enzymes that convert diacylglycerol (DAG) into phosphatidic acid (PA). The ζ isoform of DGK (DGKζ) has been reported to inhibit T-cell responsiveness by downregulating intracellular levels of DAG. However, its role in platelet function remains undefined. In this study, we show that DGKζ was expressed at significant levels in both platelets and megakaryocytes and that DGKζ-knockout (DGKζ-KO) mouse platelets were hyperreactive to glycoprotein VI (GPVI) agonists, as assessed by aggregation, spreading, granule secretion, and activation of relevant signal transduction molecules. In contrast, they were less responsive to thrombin. Platelets from DGKζ-KO mice accumulated faster on collagen-coated microfluidic surfaces under conditions of arterial shear and stopped blood flow faster after ferric chloride-induced carotid artery injury. Other measures of hemostasis, as measured by tail bleeding time and rotational thromboelastometry analysis, were normal. Interestingly, DGKζ deficiency led to increased GPVI expression on the platelet and megakaryocyte surfaces without affecting the expression of other platelet surface receptors. These results implicate DGKζ as a novel negative regulator of GPVI-mediated platelet activation that plays an important role in regulating thrombus formation in vivo.
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DGKγ Knock-Out Mice Show Impairments in Cerebellar Motor Coordination, LTD, and the Dendritic Development of Purkinje Cells through the Activation of PKCγ. eNeuro 2020; 7:ENEURO.0319-19.2020. [PMID: 32033984 PMCID: PMC7057140 DOI: 10.1523/eneuro.0319-19.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 01/18/2020] [Accepted: 01/23/2020] [Indexed: 12/02/2022] Open
Abstract
Diacylglycerol kinase γ (DGKγ) regulates protein kinase C (PKC) activity by converting DG to phosphatidic acid (PA). DGKγ directly interacts with PKCγ and is phosphorylated by PKCγ, resulting in the upregulation of lipid kinase activity. PKC dysfunction impairs motor coordination, indicating that the regulation of PKC activity is important for motor coordination. DGKγ and PKC are abundantly expressed in cerebellar Purkinje cells. However, the physiological role of DGKγ has not been elucidated. Therefore, we developed DGKγ knock-out (KO) mice and tested their cerebellar motor coordination. In DGKγ KO mice, cerebellar motor coordination and long-term depression (LTD) were impaired, and the dendrites of Purkinje cells from DGKγ KO mice were significantly retracted. Interestingly, treatment with the cPKC inhibitor Gö6976 (Gö) rescued the dendritic retraction of primary cultured Purkinje cells from DGKγ KO mice. In contrast, treatment with the PKC activator 12-o-tetradecanoylphorbol 13-acetate (TPA) reduced morphologic alterations in the dendrites of Purkinje cells from wild-type (WT) mice. In addition, we confirmed the upregulation of PKCγ activity in the cerebellum of DGKγ KO mice and rescued impaired LTD in DGKγ KO mice with a PKCγ-specific inhibitor. Furthermore, impairment of motor coordination observed in DGKγ KO mice was rescued in tm1c mice with DGKγ reexpression induced by the FLP-flippase recognition target (FRT) recombination system. These results indicate that DGKγ is involved in cerebellar LTD and the dendritic development of Purkinje cells through the regulation of PKCγ activity, and thus contributes to cerebellar motor coordination.
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9
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Aslam N, Alvi F. Simplified Model of PKCγ Signaling Dysregulation and Cytosol-to-Membrane Translocation Kinetics During Neurodegenerative Spinocerebellar Ataxia Type 14 (SCA14). Front Neurosci 2020; 13:1397. [PMID: 32082104 PMCID: PMC7004970 DOI: 10.3389/fnins.2019.01397] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 12/11/2019] [Indexed: 11/13/2022] Open
Abstract
Spinocerebellar ataxia type 14 (SCA14) is an autosomal neurodegenerative disease clinically characterized by progressive ataxia in the patient's gait, accompanied by slurred speech and abnormal eye movements. These symptoms are linked to the loss of Purkinje cells (PCs), which leads to cerebellar neurodegeneration. PC observations link the mutations in PRKCG gene encoding protein kinase C γ (PKCγ) to SCA14. Observations also show that the link between PKCγ and SCA14 relies on a gain-of-function mechanism, and, in fact, both positive and negative regulation of PKCγ expression and activity may result in changes in cellular number, size, and complexity of the dendritic arbors in PCs. Here, through a systems biology approach, we investigate a key question relating to this system: why is PKCγ membrane residence time reduced in SCA14 mutant PCs compared to wild-type (WT) PCs? In this study, we investigate this question through two contrasting PKCγ signaling models in PCs. The first model proposed in this study describes the mechanism through which PKCγ signaling activity may be regulated in WT PCs. In contrast, the second model explores how mutations in PKCγ signaling affect the state of SCA14 in PCs. Numerical simulations of both models show that, in response to extracellular stimuli-induced depolarization of the membrane compartment, PKCγ and diacylglycerol kinase γ (DGKγ) translocate to the membrane. Results from our computational approach indicate that, for the same set of parameters, PKCγ membrane residence time is shorter in the SCA14 mutant model compared to the WT model. These results show how PKCγ membrane residence time is regulated by diacylglycerol (DAG), causing translocated PKCγ to return to the cytosol as DAG levels drop. This study shows that, when the strength of the extracellular signal is held constant, the membrane lifetime of mutant PKCγ is reduced. This reduction is due to the presence of constitutively active mutant PKCγ in the cytosol. Cytosolic PKCγ, in turn, leads to phosphorylation and activation of DGKγ while it is still residing in the cytosol. This effect occurs even during the resting conditions. Thus, the SCA14 mutant model explains that, when both DAG effector molecules are active in the cytosol, their interactions in the membrane compartment are reduced, critically influencing PKCγ membrane residence time.
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Affiliation(s)
- Naveed Aslam
- BioSystOmics, Bellaire, TX, United States
- Department of Chemistry and Chemical Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Farah Alvi
- BioSystOmics, Bellaire, TX, United States
- Department of Physics, COMSATS University Islamabad, Islamabad, Pakistan
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10
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Arranz-Nicolás J, Mérida I. Biological regulation of diacylglycerol kinases in normal and neoplastic tissues: New opportunities for cancer immunotherapy. Adv Biol Regul 2020; 75:100663. [PMID: 31706704 DOI: 10.1016/j.jbior.2019.100663] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 09/20/2019] [Accepted: 09/30/2019] [Indexed: 06/10/2023]
Abstract
In the recent years, the arsenal of anti-cancer therapies has evolved to target T lymphocytes and restore their capacity to destroy tumor cells. However, the clinical success is limited, with a large number of patients that never responds and others that ultimately develop resistances. Overcoming the hypofunctional state imposed by solid tumors to T cells has revealed critical but challenging due to the complex strategies that tumors employ to evade the immune system. The Diacylglycerol kinases (DGK) limit DAG-dependent functions in T lymphocytes and their upregulation in tumor-infiltrating T lymphocytes contribute to limit T cell cytotoxic potential. DGK blockade could reinstate T cell attack on tumors, limiting at the same time tumor cell growth, thanks to the DGK positive input into several oncogenic pathways. In this review we summarize the latest findings regarding the regulation of specific DGK isoforms in healthy and anergic T lymphocytes, as well as their contribution to oncogenic phenotypes. We will also revise the latest advances in the search for pharmacological inhibitors and their potential as anti-cancer agents, either alone or in combination with immunomodulatory agents.
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Affiliation(s)
- Javier Arranz-Nicolás
- Department of Immunology and Oncology, National Center for Biotechnology (CNB-CSIC), Darwin 3, UAM Campus de Cantoblanco, 28049, Madrid, Spain
| | - Isabel Mérida
- Department of Immunology and Oncology, National Center for Biotechnology (CNB-CSIC), Darwin 3, UAM Campus de Cantoblanco, 28049, Madrid, Spain.
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11
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Barber CN, Raben DM. Roles of DGKs in neurons: Postsynaptic functions? Adv Biol Regul 2019; 75:100688. [PMID: 31836314 DOI: 10.1016/j.jbior.2019.100688] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 11/08/2019] [Accepted: 11/18/2019] [Indexed: 01/12/2023]
Abstract
Diacylglycerol kinases (DGKs) contribute to an important part of intracellular signaling because, in addition to reducing diacylglycerol levels, they generate phosphatidic acid (PtdOH) Recent research has led to the discovery of ten mammalian DGK isoforms, all of which are found in the mammalian brain. Many of these isoforms have studied functions within the brain, while others lack such understanding in regards to neuronal roles, regulation, and structural dynamics. However, while previously a neuronal function for DGKθ was unknown, it was recently found that DGKθ is required for the regulation of synaptic vesicle endocytosis and work is currently being conducted to elucidate the mechanism behind this regulation. Here we will review some of the roles of all mammalian DGKs and hypothesize additional roles. We will address the topic of redundancy among the ten DGK isoforms and discuss the possibility that DGKθ, among other DGKs, may have unstudied postsynaptic functions. We also hypothesize that in addition to DGKθ's presynaptic endocytic role, DGKθ might also regulate the endocytosis of AMPA receptors and other postsynaptic membrane proteins.
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Affiliation(s)
- Casey N Barber
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD, 21205, USA
| | - Daniel M Raben
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD, 21205, USA.
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Khrongyut S, Rawangwong A, Pidsaya A, Sakagami H, Kondo H, Hipkaeo W. Localization of phosphatidylinositol 4-phosphate 5-kinase (PIP5K) α, β, γ in the three major salivary glands in situ of mice and their response to β-adrenoceptor stimulation. J Anat 2019; 234:502-514. [PMID: 30734271 DOI: 10.1111/joa.12944] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/07/2019] [Indexed: 12/15/2022] Open
Abstract
Phosphatidylinositol 4-phosphate 5-kinase (PIP5K), which is composed of three isozymes (α, β and γ), catalyzes the production of phosphatidylinositol bisphosphate (PIP2). This phospholipid functions in membrane trafficking, as an anchor for actin cytoskeletons and as a regulator of intramembranous channels/transporters. It is also a precursor of such second messengers as diacylglycerol, inositol triphosphate and phosphatidylinositol (3,4,5)-triphosphate. In the present study, the expression and localization of endogenous PIP5Ks were examined in the three major salivary glands of young adult mice in situ. In western blotting of normal control glands, immunoreactive bands for individual PIP5Ks were detectable, with the highest density in the parotid gland and the weakest density in the submandibular gland. In immuno-light microscopy under non-stimulated condition, weak immunoreactivity for PIP5Kα was confined to the apical plasmalemma in parotid, but not sublingual or submandibular, acinar cells. Immunoreactivity for PIP5Kβ was weak to moderate and confined to ductal cells but not acinar cells, whereas that for PIP5Kγ was selectively and intensely detected in myoepithelial cells but not acinar cells, and it was weak in ductal cells in the three glands. In western blot of the parotid gland stimulated by isoproterenol, a β-adrenoceptor agonist, no changes were seen in the intensity of immunoreactive bands for any of the PIP5Ks. In contrast, in immuno-light microscopy, the apical immunoreactivity for PIP5Kα in parotid acinar cells was transiently and distinctly increased after the stimulation. The increased immunoreactivity was ultrastructurally localized on most apical microvilli and along contiguous plasma membrane, where membranous invaginations of various shapes and small vesicles were frequently found. It was thus suggested that PIP5Kα is involved in post-exocytotic membrane dynamics via microvillous membranes. The present finding further suggests that each of the three isoforms of PIP5K functions through its product PIP2 discretely in different cells of the glands to regulate saliva secretion.
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Affiliation(s)
- Suthankamon Khrongyut
- Faculty of Medicine, Department of Anatomy, Electron Microscopy Unit, Khon Kaen University, Khon Kaen, Thailand
| | - Atsara Rawangwong
- Faculty of Medicine, Department of Anatomy, Electron Microscopy Unit, Khon Kaen University, Khon Kaen, Thailand
| | - Atthapon Pidsaya
- Faculty of Medicine, Department of Anatomy, Electron Microscopy Unit, Khon Kaen University, Khon Kaen, Thailand
| | - Hiroyuki Sakagami
- Department of Anatomy, School of Medicine, Kitasato University, Sagamihara, Japan
| | - Hisatake Kondo
- Faculty of Medicine, Department of Anatomy, Electron Microscopy Unit, Khon Kaen University, Khon Kaen, Thailand.,Department of Organ Anatomy, Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - Wiphawi Hipkaeo
- Faculty of Medicine, Department of Anatomy, Electron Microscopy Unit, Khon Kaen University, Khon Kaen, Thailand
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Diacylglycerol kinase ε localizes to subsurface cisterns of cerebellar Purkinje cells. Cell Tissue Res 2017; 368:441-458. [PMID: 28191598 DOI: 10.1007/s00441-017-2579-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 01/16/2017] [Indexed: 10/20/2022]
Abstract
Following activation of Gq protein-coupled receptors, phospholipase C yields a pair of second messengers: diacylglycerol (DG) and inositol 1,4,5-trisphosphate. Diacylglycerol kinase (DGK) phosphorylates DG to produce phosphatidic acid, another second messenger. Of the DGK family, DGKε is the only DGK isoform that exhibits substrate specificity for DG with an arachidonoyl acyl chain at the sn-2 position. Recently, we demonstrated that hydrophobic residues in the N-terminus of DGKε play an important role in targeting the endoplasmic reticulum in transfected cells. However, its cellular expression and subcellular localization in the brain remain elusive. In the present study, we investigate this issue using specific DGKε antibody. DGKε was richly expressed in principal neurons of higher brain regions, including pyramidal cells in the hippocampus and neocortex, medium spiny neurons in the striatum and Purkinje cells in the cerebellum. In Purkinje cells, DGKε was localized to the subsurface cisterns and colocalized with inositol 1,4,5-trisphosphate receptor-1 in dendrites and axons. In dendrites of Purkinje cells, DGKε was also distributed in close apposition to DG lipase-α, which catalyzes arachidonoyl-DG to produce 2-arachidonoyl glycerol, a major endocannabinoid in the brain. Behaviorally, DGKε-knockout mice exhibited hyper-locomotive activities and impaired motor coordination and learning. These findings suggest that DGKε plays an important role in neuronal and brain functions through its distinct neuronal expression and subcellular localization and also through coordinated arrangement with other molecules involving the phosphoinositide signaling pathway.
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Qiu Y, Hassaninasab A, Han GS, Carman GM. Phosphorylation of Dgk1 Diacylglycerol Kinase by Casein Kinase II Regulates Phosphatidic Acid Production in Saccharomyces cerevisiae. J Biol Chem 2016; 291:26455-26467. [PMID: 27834677 DOI: 10.1074/jbc.m116.763839] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 11/08/2016] [Indexed: 11/06/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, Dgk1 diacylglycerol (DAG) kinase catalyzes the CTP-dependent phosphorylation of DAG to form phosphatidic acid (PA). The enzyme in conjunction with Pah1 PA phosphatase controls the levels of PA and DAG for the synthesis of triacylglycerol and membrane phospholipids, the growth of the nuclear/endoplasmic reticulum membrane, and the formation of lipid droplets. Little is known about how DAG kinase activity is regulated by posttranslational modification. In this work, we examined the phosphorylation of Dgk1 DAG kinase by casein kinase II (CKII). When phosphate groups were globally reduced using nonspecific alkaline phosphatase, Triton X-100-solubilized membranes from DGK1-overexpressing cells showed a 7.7-fold reduction in DAG kinase activity; the reduced enzyme activity could be increased 5.5-fold by treatment with CKII. Dgk1(1-77) expressed heterologously in Escherichia coli was phosphorylated by CKII on a serine residue, and its phosphorylation was dependent on time as well as on the concentrations of CKII, ATP, and Dgk1(1-77). We used site-specific mutagenesis, coupled with phosphorylation analysis and phosphopeptide mapping, to identify Ser-45 and Ser-46 of Dgk1 as the CKII target sites, with Ser-46 being the major phosphorylation site. In vivo, the S46A and S45A/S46A mutations of Dgk1 abolished the stationary phase-dependent stimulation of DAG kinase activity. In addition, the phosphorylation-deficient mutations decreased Dgk1 function in PA production and in eliciting pah1Δ phenotypes, such as the expansion of the nuclear/endoplasmic reticulum membrane, reduced lipid droplet formation, and temperature sensitivity. This work demonstrates that the CKII-mediated phosphorylation of Dgk1 regulates its function in the production of PA.
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Affiliation(s)
- Yixuan Qiu
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Azam Hassaninasab
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Gil-Soo Han
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - George M Carman
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
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Tabet R, Vitale N, Moine H. Fragile X syndrome: Are signaling lipids the missing culprits? Biochimie 2016; 130:188-194. [PMID: 27597551 DOI: 10.1016/j.biochi.2016.09.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 09/01/2016] [Indexed: 10/21/2022]
Abstract
Fragile X syndrome (FXS) is the most common cause of inherited intellectual disability and autism. FXS results from the absence of FMRP, an RNA binding protein associated to ribosomes that influences the translation of specific mRNAs in post-synaptic compartments of neurons. The main molecular consequence of the absence of FMRP is an excessive translation of neuronal protein in several areas of the brain. This local protein synthesis deregulation is proposed to underlie the defect in synaptic plasticity responsible for FXS. Recent findings in neurons of the fragile X mouse model (Fmr1-KO) uncovered another consequence of the lack of FMRP: a deregulation of the diacylglycerol (DAG)/phosphatidic acid (PA) homeostasis. DAG and PA are two interconvertible lipids that influence membrane architecture and that act as essential signaling molecules that activate various downstream effectors, including master regulators of local protein synthesis and actin polymerization. As a consequence, DAG and PA govern a variety of cellular processes, including cell proliferation, vesicle/membrane trafficking and cytoskeletal organization. At the synapse, the level of these lipids is proposed to influence the synaptic activation status. FMRP appears as a master regulator of this neuronal process by controlling the translation of a diacylglycerol kinase enzyme that converts DAG into PA. The deregulated levels of DAG and PA caused by the absence of FMRP could represent a novel therapeutic target for the treatment of FXS.
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Affiliation(s)
- Ricardos Tabet
- Mass General Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 CNRS, Université de Strasbourg, 67084 Strasbourg, France
| | - Hervé Moine
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67084 Strasbourg, France.
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Lee D, Kim E, Tanaka-Yamamoto K. Diacylglycerol Kinases in the Coordination of Synaptic Plasticity. Front Cell Dev Biol 2016; 4:92. [PMID: 27630986 PMCID: PMC5005321 DOI: 10.3389/fcell.2016.00092] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 08/17/2016] [Indexed: 01/07/2023] Open
Abstract
Synaptic plasticity is activity-dependent modification of the efficacy of synaptic transmission. Although, detailed mechanisms underlying synaptic plasticity are diverse and vary at different types of synapses, diacylglycerol (DAG)-associated signaling has been considered as an important regulator of many forms of synaptic plasticity, including long-term potentiation (LTP) and long-term depression (LTD). Recent evidences indicate that DAG kinases (DGKs), which phosphorylate DAG to phosphatidic acid to terminate DAG signaling, are important regulators of LTP and LTD, as supported by the results from mice lacking specific DGK isoforms. This review will summarize these studies and discuss how specific DGK isoforms distinctly regulate different forms of synaptic plasticity at pre- and postsynaptic sites. In addition, we propose a general role of DGKs as coordinators of synaptic plasticity that make local synaptic environments more permissive for synaptic plasticity by regulating DAG concentration and interacting with other synaptic proteins.
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Affiliation(s)
- Dongwon Lee
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science Daejeon, South Korea
| | - Eunjoon Kim
- Center for Synaptic Brain Dysfunctions, Institute for Basic ScienceDaejeon, South Korea; Department of Biological Sciences, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea
| | - Keiko Tanaka-Yamamoto
- Center for Functional Connectomics, Korea Institute of Science and Technology Seoul, South Korea
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Purow B. Molecular Pathways: Targeting Diacylglycerol Kinase Alpha in Cancer. Clin Cancer Res 2015; 21:5008-12. [PMID: 26420856 DOI: 10.1158/1078-0432.ccr-15-0413] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 09/10/2015] [Indexed: 02/02/2023]
Abstract
Lipid kinases have largely been neglected as targets in cancer, and an increasing number of reports suggest diacylglycerol kinase alpha (DGKα) may be one with promising therapeutic potential. DGKα is one of 10 DGK family members that convert diacylglycerol (DAG) to phosphatidic acid (PA), and both DAG and PA are critical lipid second messengers in the plasma membrane. A host of important oncogenic proteins and pathways affect cancer cells in part through DGKα, including the c-Met and VEGF receptors. Others partially mediate the effects of DGKα inhibition in cancer, such as mTOR and HIF-1α. DGKα inhibition can directly impair cancer cell viability, inhibits angiogenesis, and notably may also boost T-cell activation and enhance cancer immunotherapies. Although two structurally similar inhibitors of DGKα were established decades ago, they have seen minimal in vivo usage, and it is unlikely that either of these older DGKα inhibitors will have utility for cancer. An abandoned compound that also inhibits serotonin receptors may have more translational potential as a DGKα inhibitor, but more potent and specific DGKα inhibitors are sorely needed. Other DGK family members may also provide therapeutic targets in cancer, but require further investigation.
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Affiliation(s)
- Benjamin Purow
- Department of Neurology, University of Virginia, Charlottesville, Virginia.
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Usuki T, Sakai H, Shionoya T, Sato N, Sakane F. Expression and localization of type II diacylglycerol kinase isozymes δ and η in the developing mouse brain. J Histochem Cytochem 2014; 63:57-68. [PMID: 25362140 DOI: 10.1369/0022155414559130] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The functions of type II diacylglycerol kinase (DGK) δ and -η in the brain are still unclear. As a first step, we investigated the spatial and temporal expression of DGKδ and -η in the brains of mice. DGKδ2, but not DGKδ1, was highly expressed in layers II-VI of the cerebral cortex; CA-CA3 regions and dentate gyrus of hippocampus; mitral cell, glomerular and granule cell layers of the olfactory bulb; and the granule cell layer in the cerebellum in 1- to 32-week-old mice. DGKδ2 was expressed just after birth, and its expression levels dramatically increased from weeks 1 to 4. A substantial amount of DGKη (η1/η2) was detected in layers II-VI of the cerebral cortex, CA1 and CA2 regions and dentate gyrus of the hippocampus, mitral cell and glomerular layers of the olfactory bulb, and Purkinje cells in the cerebellum of 1- to 32-week-old mice. DGKη2 expression reached maximum levels at P5 and decreased by 4 weeks, whereas DGKη1 increased over the same time frame. These results indicate that the expression patterns of DGK isozymes differ from each other and also from other isozymes, and this suggests that DGKδ and -η play distinct and specific roles in the brain.
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Affiliation(s)
- Takako Usuki
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan. (TU, HS, TS, FS)
| | - Hiromichi Sakai
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan. (TU, HS, TS, FS)
| | - Takao Shionoya
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan. (TU, HS, TS, FS)
| | - Naruki Sato
- Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, Chiba Japan. (NS)
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan. (TU, HS, TS, FS)
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Tu-Sekine B, Goldschmidt H, Raben DM. Diacylglycerol, phosphatidic acid, and their metabolic enzymes in synaptic vesicle recycling. Adv Biol Regul 2014; 57:147-52. [PMID: 25446883 DOI: 10.1016/j.jbior.2014.09.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 09/03/2014] [Accepted: 09/03/2014] [Indexed: 01/10/2023]
Abstract
The synaptic vesicle (SV) cycle includes exocytosis of vesicles loaded with a neurotransmitter such as glutamate, coordinated recovery of SVs by endocytosis, refilling of vesicles, and subsequent release of the refilled vesicles from the presynaptic bouton. SV exocytosis is tightly linked with endocytosis, and variations in the number of vesicles, and/or defects in the refilling of SVs, will affect the amount of neurotransmitter available for release (Sudhof, 2004). There is increasing interest in the roles synaptic vesicle lipids and lipid metabolizing enzymes play in this recycling. Initial emphasis was placed on the role of polyphosphoinositides in SV cycling as outlined in a number of reviews (Lim and Wenk, 2009; Martin, 2012; Puchkov and Haucke, 2013; Rohrbough and Broadie, 2005). Other lipids are now recognized to also play critical roles. For example, PLD1 (Humeau et al., 2001; Rohrbough and Broadie, 2005) and some DGKs (Miller et al., 1999; Nurrish et al., 1999) play roles in neurotransmission which is consistent with the critical roles for phosphatidic acid (PtdOH) and diacylglycerol (DAG) in the regulation of SV exo/endocytosis (Cremona et al., 1999; Exton, 1994; Huttner and Schmidt, 2000; Lim and Wenk, 2009; Puchkov and Haucke, 2013; Rohrbough and Broadie, 2005). PLD generates phosphatidic acid by catalyzing the hydrolysis of phosphatidylcholine (PtdCho) and in some systems this PtdOH is de-phosphorylated to generate DAG. In contrast, DGK catalyzes the phosphorylation of DAG thereby converting it into PtdOH. While both enzymes are poised to regulate the levels of DAG and PtdOH, therefore, they both lead to the generation of PtdOH and could have opposite effects on DAG levels. This is particularly important for SV cycling as PtdOH and DAG are both needed for evoked exocytosis (Lim and Wenk, 2009; Puchkov and Haucke, 2013; Rohrbough and Broadie, 2005). Two lipids and their involved metabolic enzymes, two sphingolipids have also been implicated in exocytosis: sphingosine (Camoletto et al., 2009; Chan et al., 2012; Chan and Sieburth, 2012; Darios et al., 2009; Kanno et al., 2010; Rohrbough et al., 2004) and sphingosine-1-phosphate (Chan, Hu, 2012; Chan and Sieburth, 2012; Kanno et al., 2010). Finally a number of reports have focused on the somewhat less well studies roles of sphingolipids and cholesterol in SV cycling. In this report, we review the recent understanding of the roles PLDs, DGKs, and DAG lipases, as well as sphingolipids and cholesterol play in synaptic vesicle cycling.
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Affiliation(s)
- Becky Tu-Sekine
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Hana Goldschmidt
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Daniel M Raben
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Ishisaka M, Hara H. The Roles of Diacylglycerol Kinases in the Central Nervous System: Review of Genetic Studies in Mice. J Pharmacol Sci 2014; 124:336-43. [DOI: 10.1254/jphs.13r07cr] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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21
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Ueda S, Tu-Sekine B, Yamanoue M, Raben DM, Shirai Y. The expression of diacylglycerol kinase theta during the organogenesis of mouse embryos. BMC DEVELOPMENTAL BIOLOGY 2013; 13:35. [PMID: 24079595 PMCID: PMC3850696 DOI: 10.1186/1471-213x-13-35] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 09/27/2013] [Indexed: 12/11/2022]
Abstract
Background Diacylglycerol kinase (DGK) is a key enzyme that regulates diacylglycerol (DG) turnover and is involved in a variety of physiological functions. The isoform DGKθ has a unique domain structure and is the sole member of type V DGK. To reveal the spatial and temporal expression of DGKθ we performed immunohistochemical staining on paraffin sections of mouse embryos. Results At an early stage of development (E10.5 and 11.5), the expression of DGKθ was prominently detected in the brain, spinal cord, dorsal root ganglion, and limb bud, and was also moderately detected in the bulbus cordis and the primordium of the liver and gut. At later stages (E12.5 and 14.5), DGKθ expression persisted or increased in the neocortex, epithalamus, hypothalamus, medulla oblongata, and pons. DGKθ was also evident in the epidermis, and nearly all epithelia of the oropharyngeal membrane, digestive tract, and bronchea. At prenatal developmental stages (E16.5 and E18.5), the expression pattern of DGKθ was maintained in the central nervous system, intestine, and kidney, but was attenuated in the differentiated epidermis. Conclusion These results suggest that DGKθ may play important physiological roles not only in the brain, but also in diverse organs and tissues during the embryonic stages.
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Affiliation(s)
- Shuji Ueda
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, Japan.
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22
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Qiu Y, Fakas S, Han GS, Barbosa AD, Siniossoglou S, Carman GM. Transcription factor Reb1p regulates DGK1-encoded diacylglycerol kinase and lipid metabolism in Saccharomyces cerevisiae. J Biol Chem 2013; 288:29124-33. [PMID: 23970552 PMCID: PMC3790011 DOI: 10.1074/jbc.m113.507392] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, the DGK1-encoded diacylglycerol kinase catalyzes the CTP-dependent phosphorylation of diacylglycerol to form phosphatidate. This enzyme, in conjunction with PAH1-encoded phosphatidate phosphatase, controls the levels of phosphatidate and diacylglycerol for phospholipid synthesis, membrane growth, and lipid droplet formation. In this work, we showed that a functional level of diacylglycerol kinase is regulated by the Reb1p transcription factor. In the electrophoretic mobility shift assay, purified recombinant Reb1p was shown to specifically bind its consensus recognition sequence (CGGGTAA, -166 to -160) in the DGK1 promoter. Analysis of cells expressing the PDGK1-lacZ reporter gene showed that mutations (GT→TG) in the Reb1p-binding sequence caused an 8.6-fold reduction in β-galactosidase activity. The expression of DGK1(reb1), a DGK1 allele containing the Reb1p-binding site mutation, was greatly lower than that of the wild type allele, as indicated by analyses of DGK1 mRNA, Dgk1p, and diacylglycerol kinase activity. In the presence of cerulenin, an inhibitor of de novo fatty acid synthesis, the dgk1Δ mutant expressing DGK1(reb1) exhibited a significant defect in growth as well as in the synthesis of phospholipids from triacylglycerol mobilization. Unlike DGK1, the DGK1(reb1) expressed in the dgk1Δ pah1Δ mutant did not result in the nuclear/endoplasmic reticulum membrane expansion, which occurs in cells lacking phosphatidate phosphatase activity. Taken together, these results indicate that the Reb1p-mediated regulation of diacylglycerol kinase plays a major role in its in vivo functions in lipid metabolism.
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Affiliation(s)
- Yixuan Qiu
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901 and
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Cai K, Sewer MB. cAMP-stimulated transcription of DGKθ requires steroidogenic factor 1 and sterol regulatory element binding protein 1. J Lipid Res 2013; 54:2121-2132. [PMID: 23610160 DOI: 10.1194/jlr.m035634] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Diacylglycerol kinase (DGK)θ is a lipid kinase that phosphorylates diacylglycerol to form phosphatidic acid (PA). We have previously shown that PA is a ligand for the nuclear receptor steroidogenic factor 1 (SF1) and that cAMP-stimulated expression of SF1 target genes requires DGKθ. In this study, we sought to investigate the role of cAMP signaling in regulating DGKθ gene expression. Real time RT-PCR and Western blot analysis revealed that dibutyryl cAMP (Bt2cAMP) increased the mRNA and protein expression, respectively, of DGKθ in H295R human adrenocortical cells. SF1 and sterol regulatory element binding protein 1 (SREBP1) increased the transcriptional activity of a reporter plasmid containing 1.5 kb of the DGKθ promoter fused to the luciferase gene. Mutation of putative cAMP responsive sequences abolished SF1- and SREBP-dependent DGKθ reporter gene activation. Consistent with this finding, chromatin immunoprecipitation assay demonstrated that Bt2cAMP signaling increased the recruitment of SF1 and SREBP1 to the DGKθ promoter. Coimmunoprecipitation assay revealed that SF1 and SREBP1 interact, suggesting that the two transcription factors form a complex on the DGKθ promoter. Finally, silencing SF1 and SREBP1 abolished cAMP-stimulated DGKθ expression. Taken together, we demonstrate that SF1 and SREBP1 activate DGKθ transcription in a cAMP-dependent manner in human adrenocortical cells.
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Affiliation(s)
- Kai Cai
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093
| | - Marion B Sewer
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093.
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Sakai H, Sakane F. Recent progress on type II diacylglycerol kinases: the physiological functions of diacylglycerol kinase , and and their involvement in disease. J Biochem 2012; 152:397-406. [DOI: 10.1093/jb/mvs104] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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Ishisaka M, Kakefuda K, Oyagi A, Ono Y, Tsuruma K, Shimazawa M, Kitaichi K, Hara H. Diacylglycerol kinase β knockout mice exhibit attention-deficit behavior and an abnormal response on methylphenidate-induced hyperactivity. PLoS One 2012; 7:e37058. [PMID: 22590645 PMCID: PMC3349656 DOI: 10.1371/journal.pone.0037058] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 04/12/2012] [Indexed: 01/22/2023] Open
Abstract
Background Diacylglycerol kinase (DGK) is an enzyme that phosphorylates diacylglycerol to produce phosphatidic acid. DGKβ is one of the subtypes of the DGK family and regulates many intracellular signaling pathways in the central nervous system. Previously, we demonstrated that DGKβ knockout (KO) mice showed various dysfunctions of higher brain function, such as cognitive impairment (with lower spine density), hyperactivity, reduced anxiety, and careless behavior. In the present study, we conducted further tests on DGKβ KO mice in order to investigate the function of DGKβ in the central nervous system, especially in the pathophysiology of attention deficit hyperactivity disorder (ADHD). Methodology/Principal Findings DGKβ KO mice showed attention-deficit behavior in the object-based attention test and it was ameliorated by methylphenidate (MPH, 30 mg/kg, i.p.). In the open field test, DGKβ KO mice displayed a decreased response to the locomotor stimulating effects of MPH (30 mg/kg, i.p.), but showed a similar response to an N-methyl-d-aspartate (NMDA) receptor antagonist, MK-801 (0.3 mg/kg, i.p.), when compared to WT mice. Examination of the phosphorylation of extracellular signal-regulated kinase (ERK), which is involved in regulation of locomotor activity, indicated that ERK1/2 activation induced by MPH treatment was defective in the striatum of DGKβ KO mice. Conclusions/Significance These findings suggest that DGKβ KO mice showed attention-deficit and hyperactive phenotype, similar to ADHD. Furthermore, the hyporesponsiveness of DGKβ KO mice to MPH was due to dysregulation of ERK phosphorylation, and that DGKβ has a pivotal involvement in ERK regulation in the striatum.
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Affiliation(s)
- Mitsue Ishisaka
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan
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Zhang N, Li B, Al-Ramahi I, Cong X, Held JM, Kim E, Botas J, Gibson BW, Ellerby LM. Inhibition of lipid signaling enzyme diacylglycerol kinase epsilon attenuates mutant huntingtin toxicity. J Biol Chem 2012; 287:21204-13. [PMID: 22511757 DOI: 10.1074/jbc.m111.321661] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Huntington disease (HD) is a dominantly inherited neurodegenerative disease caused by a polyglutamine expansion in the protein huntingtin (Htt). Striatal and cortical neuronal loss are prominent features of this disease. No disease-modifying treatments have been discovered for HD. To identify new therapeutic targets in HD, we screened a kinase inhibitor library for molecules that block mutant Htt cellular toxicity in a mouse HD striatal cell model, Hdh(111Q/111Q) cells. We found that diacylglycerol kinase (DGK) inhibitor II (R59949) decreased caspase-3/7 activity after serum withdrawal in striatal Hdh(111Q/111Q) cells. In addition, R59949 decreased the accumulation of a 513-amino acid N-terminal Htt fragment processed by caspase-3 and blocked alterations in lipid metabolism during serum withdrawal. To identify the diacylglycerol kinase mediating this effect, we knocked down all four DGK isoforms expressed in the brain (β, γ, ε, and ζ) using siRNA. Only the knockdown of the family member, DGKε, blocked striatal Hdh(111Q/111Q)-mediated toxicity. We also investigated the significance of these findings in vivo. First, we found that reduced function of the Drosophila DGKε homolog significantly improves Htt-induced motor dysfunction in a fly model of HD. In addition, we find that the levels of DGKε are increased in the striatum of R6/2 HD transgenic mice when compared with littermate controls. Together, these findings indicate that increased levels of kinase DGKε contribute to HD pathogenesis and suggest that reducing its levels or activity is a potential therapy for HD.
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Affiliation(s)
- Ningzhe Zhang
- Buck Institute for Research on Aging, Novato, California 94945, USA
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NMDA receptor-mediated Ca2+ influx triggers nucleocytoplasmic translocation of diacylglycerol kinase ζ under oxygen–glucose deprivation conditions, an in vitro model of ischemia, in rat hippocampal slices. Histochem Cell Biol 2012; 137:499-511. [DOI: 10.1007/s00418-011-0907-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/23/2011] [Indexed: 02/07/2023]
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Rincón E, Gharbi SI, Santos-Mendoza T, Mérida I. Diacylglycerol kinase ζ: At the crossroads of lipid signaling and protein complex organization. Prog Lipid Res 2012; 51:1-10. [DOI: 10.1016/j.plipres.2011.10.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Shulga YV, Topham MK, Epand RM. Regulation and functions of diacylglycerol kinases. Chem Rev 2011; 111:6186-208. [PMID: 21800853 DOI: 10.1021/cr1004106] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Yulia V Shulga
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
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Tu-Sekine B, Raben DM. Regulation and roles of neuronal diacylglycerol kinases: a lipid perspective. Crit Rev Biochem Mol Biol 2011; 46:353-64. [PMID: 21539478 DOI: 10.3109/10409238.2011.577761] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Diacylglycerol kinases (DGKs) are a class of enzymes that catalyze the ATP-dependent conversion of diacylglycerol (DAG) to phosphatidic acid (PtdOH), resulting in the coordinate regulation of these two lipid second messengers. This regulation is particularly important in the nervous system where it is now well-established that DAG and PtdOH serve very important roles in modulating a variety of neurological functions. There are currently 10 identified mammalian DGKs, organized into five classes or "Types" based upon similarities in their primary sequences. A number of studies have identified eight of these isoforms in various regions of the mammalian central nervous system (CNS): DGK-α, DGK-β, DGK-γ, DGK-η, DGK-ζ, DGK-ι, DGK-ϵ, and DGK-θ. Further studies have provided compelling evidence supporting roles for these enzymes in neuronal spine density, myelination, synaptic activity, neuronal plasticity, epileptogenesis and neurotransmitter release. The physiological regulation of these enzymes is less clear. Like all interfacial enzymes, DGKs metabolize their hydrophobic substrate (DAG) at a membrane-aqueous interface. Therefore, these enzymes can be regulated by alterations in their subcellular localization, enzymatic activity, and/or membrane association. In this review, we summarize what is currently understood about the localization and regulation of the neuronal DGKs in the mammalian CNS.
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Affiliation(s)
- Becky Tu-Sekine
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, 21205 MD, USA
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Giusto NM, Pasquaré SJ, Salvador GA, Ilincheta de Boschero MG. Lipid second messengers and related enzymes in vertebrate rod outer segments. J Lipid Res 2009; 51:685-700. [PMID: 19828910 DOI: 10.1194/jlr.r001891] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Rod outer segments (ROSs) are specialized light-sensitive organelles in vertebrate photoreceptor cells. Lipids in ROS are of considerable importance, not only in providing an adequate environment for efficient phototransduction, but also in originating the second messengers involved in signal transduction. ROSs have the ability to adapt the sensitivity and speed of their responses to ever-changing conditions of ambient illumination. A major contributor to this adaptation is the light-driven translocation of key signaling proteins into and out of ROS. The present review shows how generation of the second lipid messengers from phosphatidylcholine, phosphatidic acid, and diacylglycerol is modulated by the different illumination states in the vertebrate retina. Findings suggest that the light-induced translocation of phototransduction proteins influences the enzymatic activities of phospholipase D, lipid phosphate phosphatase, diacylglyceride lipase, and diacylglyceride kinase, all of which are responsible for the generation of the second messenger molecules.
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Affiliation(s)
- Norma M Giusto
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.
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Lung M, Shulga YV, Ivanova PT, Myers DS, Milne SB, Brown HA, Topham MK, Epand RM. Diacylglycerol kinase epsilon is selective for both acyl chains of phosphatidic acid or diacylglycerol. J Biol Chem 2009; 284:31062-73. [PMID: 19744926 DOI: 10.1074/jbc.m109.050617] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The phosphatidylinositol (PI) cycle mediates many cellular events by controlling the metabolism of many lipid second messengers. Diacylglycerol kinase epsilon (DGK epsilon) has an important role in this cycle. DGK epsilon is the only DGK isoform to show inhibition by its product phosphatidic acid (PA) as well as substrate specificity for sn-2 arachidonoyl-diacylglycerol (DAG). Here, we show that this inhibition and substrate specificity are both determined by selectivity for a combination of the sn-1 and sn-2 acyl chains of PA or DAG, respectively, preferring the most prevalent acyl chain composition of lipids involved specifically in the PI cycle, 1-stearoyl-2-arachidonoyl. Although the difference in rate for closely related lipid species is small, there is a significant enrichment of 1-stearoyl-2-arachidonoyl PI because of the cyclical nature of PI turnover. We also show that the inhibition of DGK epsilon by PA is competitive and that the deletion of the hydrophobic segment and cationic cluster of DGK epsilon does not affect its selectivity for the acyl chains of PA or DAG. Thus, this active site not only recognizes the lipid headgroup but also a combination of the two acyl chains in PA or DAG. We propose a mechanism of DGK epsilon regulation where its dual acyl chain selectivity is used to negatively regulate its enzymatic activity in a manner that ensures DGK epsilon remains committed to the PI turnover cycle. This novel mechanism of enzyme regulation within a signaling pathway could serve as a template for the regulation of enzymes in other pathways in the cell.
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Affiliation(s)
- Michael Lung
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
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Nakano T, Iseki K, Hozumi Y, Kawamae K, Wakabayashi I, Goto K. Brain trauma induces expression of diacylglycerol kinase ζ in microglia. Neurosci Lett 2009; 461:110-5. [DOI: 10.1016/j.neulet.2009.06.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2009] [Revised: 03/31/2009] [Accepted: 06/01/2009] [Indexed: 11/26/2022]
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Hirose M, Takeishi Y, Niizeki T, Shimojo H, Nakada T, Kubota I, Nakayama J, Mende U, Yamada M. Diacylglycerol kinase ζ inhibits Gαq-induced atrial remodeling in transgenic mice. Heart Rhythm 2009; 6:78-84. [DOI: 10.1016/j.hrthm.2008.10.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Accepted: 10/10/2008] [Indexed: 10/21/2022]
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Niizeki T, Takeishi Y, Kitahara T, Arimoto T, Koyama Y, Goto K, Mende U, Kubota I. Diacylglycerol kinase zeta rescues G alpha q-induced heart failure in transgenic mice. Circ J 2008; 72:309-17. [PMID: 18219172 DOI: 10.1253/circj.72.309] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND The G alpha q protein-coupled receptor (GPCR) signaling pathway, which includes diacylglycerol (DAG) and protein kinase C (PKC), plays a critical role in the development of cardiac hypertrophy and heart failure (HF). It has been reported that the expression of a constitutively active mutant of the G protein alpha q subunit in the hearts of transgenic mice (G alpha q-TG) induces cardiac hypertrophy and lethal HF. DAG kinase (DGK) catalyzes DAG and controls its cellular levels, thus acting as a regulator of GPCR signaling. It has been found that transgenic mice with cardiac-specific overexpression of DGK zeta (DGK zeta-TG) inhibit GPCR agonist-induced activation of the DAG-PKC signaling and subsequent cardiac hypertrophy, so this study tested the hypothesis that DGK zeta could rescue G alpha q-TG mice from developing HF. METHODS AND RESULTS Double transgenic mice (G alpha q/DGK zeta-TG) with cardiac-specific overexpression of both DGK zeta and G alpha q were generated by crossing G alpha q-TG with DGK zeta-TG mice, and the pathophysiological consequences were analyzed. DGK zeta prevented cardiac dysfunction, determined by dilatation of left ventricular (LV) dimensions, reduction of LV fractional shortening, and marked increases in LV end-diastolic pressure in G alpha q-TG mice. Translocation of PKC isoforms, phosphorylation activity of c-jun N-terminal kinase and p38 mitogen-activated protein kinase in G alpha q-TG mice were attenuated by DGK zeta. DGK zeta improved the survival rate of G alpha q-TG mice. CONCLUSIONS These results demonstrate the first evidence that DGK zeta blocks cardiac dysfunction and progression to lethal HF by activated G alpha q protein without detectable adverse effects in the in-vivo heart and suggest that DGK zeta is a novel therapeutic target for HF.
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Affiliation(s)
- Takeshi Niizeki
- Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan
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Delplanque J, Devos D, Vuillaume I, De Becdelievre A, Vangelder E, Maurage CA, Dujardin K, Destée A, Sablonnière B. Slowly progressive spinocerebellar ataxia with extrapyramidal signs and mild cognitive impairment (SCA21). THE CEREBELLUM 2008; 7:179-83. [DOI: 10.1007/s12311-008-0014-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
DGKs (diacylglycerol kinases) are members of a unique and conserved family of intracellular lipid kinases that phosphorylate DAG (diacylglycerol), catalysing its conversion into PA (phosphatidic acid). This reaction leads to attenuation of DAG levels in the cell membrane, regulating a host of intracellular signalling proteins that have evolved the ability to bind this lipid. The product of the DGK reaction, PA, is also linked to the regulation of diverse functions, including cell growth, membrane trafficking, differentiation and migration. In multicellular eukaryotes, DGKs provide a link between lipid metabolism and signalling. Genetic experiments in Caenorhabditis elegans, Drosophila melanogaster and mice have started to unveil the role of members of this protein family as modulators of receptor-dependent responses in processes such as synaptic transmission and photoreceptor transduction, as well as acquired and innate immune responses. Recent discoveries provide new insights into the complex mechanisms controlling DGK activation and their participation in receptor-regulated processes. After more than 50 years of intense research, the DGK pathway emerges as a key player in the regulation of cell responses, offering new possibilities of therapeutic intervention in human pathologies, including cancer, heart disease, diabetes, brain afflictions and immune dysfunctions.
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Goto K, Hozumi Y, Nakano T, Saino-Saito S, Martelli AM. Lipid Messenger, Diacylglycerol, and its Regulator, Diacylglycerol Kinase, in Cells, Organs, and Animals: History and Perspective. TOHOKU J EXP MED 2008; 214:199-212. [DOI: 10.1620/tjem.214.199] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Kaoru Goto
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine
| | - Yasukazu Hozumi
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine
| | - Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine
| | - Sachiko Saino-Saito
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine
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Sakane F, Imai SI, Kai M, Yasuda S, Kanoh H. Diacylglycerol kinases: Why so many of them? Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1771:793-806. [PMID: 17512245 DOI: 10.1016/j.bbalip.2007.04.006] [Citation(s) in RCA: 247] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Revised: 03/28/2007] [Accepted: 04/06/2007] [Indexed: 11/17/2022]
Abstract
Diacylglycerol (DAG) kinase (DGK) modulates the balance between the two signaling lipids, DAG and phosphatidic acid (PA), by phosphorylating DAG to yield PA. To date, ten mammalian DGK isozymes have been identified. In addition to the C1 domains (protein kinase C-like zinc finger structures) conserved commonly in all DGKs, these isoforms possess a variety of regulatory domains of known and/or predicted functions, such as a pair of EF-hand motifs, a pleckstrin homology domain, a sterile alpha motif domain and ankyrin repeats. Beyond our expectations, recent studies have revealed that DGK isozymes play pivotal roles in a wide variety of signal transduction pathways conducting development, neural and immune responses, cytoskeleton reorganization and carcinogenesis. Moreover, there has been rapidly growing evidence indicating that individual DGK isoforms exert their specific roles through interactions with unique partner proteins such as protein kinase Cs, Ras guanyl nucleotide-releasing protein, chimaerins and phosphatidylinositol-4-phosphate 5-kinase. Therefore, an emerging paradigm for DGK is that the individual DGK isoforms assembled in their own signaling complexes should carry out spatio-temporally segregated tasks for a wide range of biological processes via regulating local, but not global, concentrations of DAG and/or PA.
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Affiliation(s)
- Fumio Sakane
- Department of Biochemistry, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo 060-8556, Japan.
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Kobayashi N, Hozumi Y, Ito T, Hosoya T, Kondo H, Goto K. Differential subcellular targeting and activity-dependent subcellular localization of diacylglycerol kinase isozymes in transfected cells. Eur J Cell Biol 2007; 86:433-44. [PMID: 17599647 DOI: 10.1016/j.ejcb.2007.05.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 04/28/2007] [Accepted: 05/15/2007] [Indexed: 11/22/2022] Open
Abstract
Diacylglycerol kinase (DGK) plays a pivotal role in cellular signal transduction through regulating levels of the second messenger diacylglycerol (DG). Previous studies have revealed that DGK is composed of a family of isozymes that show remarkable heterogeneity in terms of molecular structure, functional domains, tissue and cellular gene expression. Recently, it has been shown that DG is produced in various subcellular compartments including the plasma membrane, internal membranes, cytoskeleton, and nucleus. However, it remains unclear how DG is regulated at distinct subcellular sites. To address this point, we have used an epitope-tag expression system in cultured cells and investigated the subcellular localization of DGK isozymes under the same experimental conditions. We show here that DGK isozymes are targeted differentially to unique subcellular sites in transfected COS7 cells, including the cytoplasm, actin stress fibers, Golgi complex, endoplasmic reticulum, and nucleus. It is also shown that among the isozymes overexpression of DGKbeta causes fragmentation of actin stress fibers while a kinase-dead mutant of DGKbeta abolishes its colocalization with actin stress fibers. These data strongly suggest that each isozyme may be responsible for the metabolism of DG that is produced upon stimulation at a different and specific subcellular site and that DGKbeta activity might have effects on the reorganization of actin stress fibers in transfected COS7 cells.
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Affiliation(s)
- Naoki Kobayashi
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-nishi 2-2-2, Yamagata 990-9585, Japan
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Niizeki T, Takeishi Y, Arimoto T, Takahashi H, Shishido T, Koyama Y, Goto K, Walsh RA, Kubota I. Cardiac-specific overexpression of diacylglycerol kinase ζ attenuates left ventricular remodeling and improves survival after myocardial infarction. Am J Physiol Heart Circ Physiol 2007; 292:H1105-12. [PMID: 17071729 DOI: 10.1152/ajpheart.00927.2006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Left ventricular (LV) remodeling, including cardiomyocyte necrosis, scar formation, LV geometric changes, and cardiomyocyte hypertrophy, contributes to cardiac dysfunction and mortality after myocardial infarction (MI). Although precise cellular signaling mechanisms for LV remodeling are not fully elucidated, Gq protein-coupled receptor signaling pathway, including diacylglycerol (DAG) and PKC, are involved in this process. DAG kinase (DGK) phosphorylates DAG and controls cellular DAG levels, thus acting as a negative regulator of PKC and subsequent cellular signaling. We previously reported that DGK inhibited angiotensin II and phenylephrine-induced activation of the DAG-PKC signaling and subsequent cardiac hypertrophy. The purpose of this study was to examine whether DGK modifies LV remodeling after MI. Left anterior descending coronary artery was ligated in transgenic mice with cardiac-specific overexpression of DGKζ (DGKζ-TG) and wild-type (WT) mice. LV chamber dilatation (4.12 ± 0.10 vs. 4.53 ± 0.32 mm, P < 0.01), reduction of LV systolic function (34.8 ± 8.3% vs. 28.3 ± 4.8%, P < 0.01), and increases in LV weight (95 ± 3.6 vs. 111 ± 4.1 mg, P < 0.05) and lung weight (160 ± 15 vs. 221 ± 25 mg, P < 0.05) at 4 wk after MI were attenuated in DGKζ-TG mice compared with WT mice. In the noninfarct area, fibrosis fraction (0.51 ± 0.04, P < 0.01) and upregulation of profibrotic genes, such as transforming growth factor-β1 ( P < 0.01), collagen type I ( P < 0.05), and collagen type III ( P < 0.01), were blocked in DGKζ-TG mice. The survival rate at 4 wk after MI was higher in DGKζ-TG mice than in WT mice (61% vs. 37%, P < 0.01). In conclusion, these results demonstrate the first evidence that DGKζ suppresses LV structural remodeling and fibrosis and improves survival after MI. DGKζ may be a potential novel therapeutic target to prevent LV remodeling after MI.
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Affiliation(s)
- Takeshi Niizeki
- Department of Cardiology, Yamagata University School of Medicine, 2-2-2 Iida-Nishi, Yamagata, Japan 990-9585
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Goto K, Hozumi Y, Nakano T, Saino SS, Kondo H. Cell Biology and Pathophysiology of the Diacylglycerol Kinase Family: Morphological Aspects in Tissues and Organs. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 264:25-63. [DOI: 10.1016/s0074-7696(07)64002-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Harada M, Takeishi Y, Arimoto T, Niizeki T, Kitahara T, Goto K, Walsh RA, Kubota I. Diacylglycerol Kinase .XI. Attenuates Pressure Overload-Induced Cardiac Hypertrophy. Circ J 2007; 71:276-82. [PMID: 17251681 DOI: 10.1253/circj.71.276] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND The Gaq protein-coupled receptor (GPCR) signaling pathway, which includes diacylglycerol (DAG) and protein kinase C (PKC), plays a critical role in the development of cardiac hypertrophy and heart failure. DAG kinase (DGK) phosphorylates DAG and controls cellular DAG levels, thus acting as a regulator of GPCR signaling. It has been previously reported that DGK inhibited GPCR agonist-induced activation of the DAG-PKC signaling and subsequent cardiomyocyte hypertrophy, so the purpose of this study was to examine whether DGK modifies the development of cardiac hypertrophy induced by pressure overload. METHODS AND RESULTS Thoracic transverse aortic constriction (TAC) was created in transgenic mice with cardiac-specific overexpression of DGKzeta (DGKzeta-TG) and wild-type (WT) mice. Increases in heart weight at 4 weeks after TAC were attenuated in DGKzeta-TG mice compared with WT mice. Increases in interventricular septal thickness, dilatation of the left ventricular cavity, and decreases in left ventricular systolic function in WT mice were observed with echocardiography at 4 weeks after TAC surgery. However, these structural and functional changes after TAC were attenuated in DGKzeta-TG mice. In WT mice, cardiac fibrosis and up-regulation of profibrotic genes, such as transforming growth factor-beta1, collagen type I, and collagen type III, were observed at 4 weeks after TAC. However, cardiac fibrosis and gene induction of type I and type III collagens, but not transforming growth factor-beta1, were blocked in DGKzeta-TG mice. CONCLUSION These results are the first in vivo evidence that DGKzeta suppresses cardiac hypertrophy and fibrosis and prevents impaired left ventricular systolic function caused by pressure overload.
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Affiliation(s)
- Mutsuo Harada
- Department of Cardiology, Pulmonology and Nephrology, Yamagata University School of Medicine, Japan
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Yamaguchi Y, Shirai Y, Matsubara T, Sanse K, Kuriyama M, Oshiro N, Yoshino KI, Yonezawa K, Ono Y, Saito N. Phosphorylation and Up-regulation of Diacylglycerol Kinase γ via Its Interaction with Protein Kinase Cγ. J Biol Chem 2006. [DOI: 10.1016/s0021-9258(19)84076-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Yamaguchi Y, Shirai Y, Matsubara T, Sanse K, Kuriyama M, Oshiro N, Yoshino KI, Yonezawa K, Ono Y, Saito N. Phosphorylation and Up-regulation of Diacylglycerol Kinase γ via Its Interaction with Protein Kinase Cγ. J Biol Chem 2006; 281:31627-37. [PMID: 16905533 DOI: 10.1074/jbc.m606992200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Diacylglycerol (DAG) acts as an allosteric activator of protein kinase C (PKC) and is converted to phosphatidic acid by DAG kinase (DGK). Therefore, DGK is thought to be a negative regulator of PKC activation. Here we show molecular mechanisms of functional coupling of the two kinases. gammaPKC directly associated with DGKgamma through its accessory domain (AD), depending on Ca2+ as well as phosphatidylserine/diolein in vitro. Mass spectrometric analysis and mutation studies revealed that gammaPKC phosphorylated Ser-776 and Ser-779 in the AD of DGKgamma. The phosphorylation by gammaPKC resulted in activation of DGKgamma because a DGKgamma mutant in which Ser-776 and Ser-779 were substituted with glutamic acid to mimic phosphorylation exhibited significantly higher activity compared with wild type DGKgamma and an unphosphorylatable DGKgamma mutant. Importantly, the interaction of the two kinases and the phosphorylation of DGKgamma by gammaPKC could be confirmed in vivo, and overexpression of the AD of DGKgamma inhibited re-translocation of gammaPKC. These results demonstrate that localization and activation of the functionally correlated kinases, gammaPKC and DGKgamma, are spatio-temporally orchestrated by their direct association and phosphorylation, contributing to subtype-specific regulation of DGKgamma and DAG signaling.
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Affiliation(s)
- Yasuto Yamaguchi
- Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
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Sasaki H, Hozumi Y, Hasegawa H, Ito T, Takagi M, Ogino T, Watanabe M, Goto K. Gene expression and localization of diacylglycerol kinase isozymes in the rat spinal cord and dorsal root ganglia. Cell Tissue Res 2006; 326:35-42. [PMID: 16758180 DOI: 10.1007/s00441-006-0219-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2006] [Accepted: 04/11/2006] [Indexed: 01/19/2023]
Abstract
The dorsal root ganglion (DRG) and dorsal horn of the spinal cord are areas through which primary afferent information passes enroute to the brain. Previous studies have reported that, during normal neuronal activity, the regional distribution of a second messenger, diacylglycerol (DG), which is derived from phosphoinositide turnover, is diverse in these areas. However, the way that DG is regulated in these organs remains unknown. The present study was performed to investigate mRNA expression and protein localization of DG kinase (DGK) isozymes, which play a central role in DG metabolism. Gene expression for DGK isozymes was detected with variable regional distributions and intensities in the spinal cord. Among the isozymes, most intense signals were found for DGKzeta and DGKiota in the DRG. By immunohistochemical analysis, DGKzeta immunoreactivity was detected heterogeneously in the nucleus and cytoplasm of small DRG neurons with variable levels of distribution, whereas it was detected exclusively in the cytoplasm of large neurons. On the other hand, DGKiota immunoreactivity was distributed solely in the cytoplasm of most of the DRG neurons. Double-immunofluorescent imaging of these isozymes showed that they coexisted in a large population of DRG neurons at distinct subcellular sites, i.e., DGKzeta in the nucleus and DGKiota in the cytoplasm. Thus, DGK isozymes may have different functional roles at distinct subcellular sites. Furthermore, the heterogeneous subcellular localization of DGKzeta between the nucleus and cytoplasm implies the possible translocation of this isozyme in small DRG neurons under various conditions.
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Affiliation(s)
- Hayato Sasaki
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-Nishi 2-2-2, Yamagata, 990-9585, Japan
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Abstract
Gliomas are the most common major subgroup of primary CNS tumours. Approximately 17,000 new cases are reported each year and, of these, 11,500 patients die. Glioblastoma multiforme (GBM) is highly proliferative and typically invades distal portions of the brain, thereby making complete surgical resection of these tumours nearly impossible. Moreover, GBMs are often resistant to current chemotherapy and radiation regimens. Therefore, there is a need for better therapeutic interventions. One class of proteins that is involved in the formation of malignant brain tumours is protein kinase C (PKC) and these kinases have not been thoroughly explored for their chemotherapeutic value in GBMs. The PKC isozyme, PKCeta (PKC-eta) increases cell proliferation and resistance to radiation of GBM cell lines. These properties make PKCeta an attractive target for chemotherapeutic intervention in the management of GBMs.
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Affiliation(s)
- Patrick M Martin
- Department of Pathology, University of Virginia, Charlottesville, VA, USA.
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50
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Abstract
PURPOSE Diacylglycerol kinase epsilon (DGKepsilon) regulates seizure susceptibility and long-term potentiation through arachidonoyl-inositol lipid signaling. We studied the significance of arachidonoyl-diacylglycerol (20:4 DAG) in epileptogenesis in DGKepsilon-deficient mice undergoing rapid kindling epileptogenesis. METHODS Tripolar electrode units were implanted in right dorsal hippocampi of male DGKepsilon(+/+) and DGKepsilon(-/-) mice. Ten days after surgery, kindling was achieved by stimulating 6 times daily for 4 days with a subconvulsive electrical stimulation (10-s train of 50-Hz biphasic pulses, 75-200 muA amplitude) at 30-min intervals. After 1 week, mice were rekindled. EEGs were recorded and analyzed to characterize epileptogenic events as spikes, sharp waves, or abnormal amplitudes and rhythms. Right hippocampi were analyzed by histology [Timm's staining, neuropeptide Y (NPY) and glial fibrillary acidic protein immunoreactivity], and for DNA fragmentation (TUNEL). RESULTS DGKepsilon(-/-) mice had significantly fewer motor seizure and epileptic events compared with DGKepsilon(+/+) mice from the second day of stimulation. These differences were maintained during rekindling. DGKepsilon(-/-) mice also exhibited low-amplitude spike-wave complexes, short spreading depression, and predominant lower-frequency (1-4 Hz) bands throughout stimulation, whereas DGKepsilon(+/+) mice exhibited increased high-frequency bands (4-8 Hz; 8-15 Hz) from the second day of stimulation, as determined by power spectral analysis. DGKepsilon(-/-) mice displayed no sprouting in the supragranular area or NPY inmunoreactivity in the hilus and had weak astrocyte reactivation in all hippocampal areas. No TUNEL-positive cells were detected in any group of mice. CONCLUSIONS DGKepsilon modulates kindling epileptogenesis through inositol lipid signaling. Because arachidonate-containing diacylglycerol phosphorylation to phosphatidic acid is selectively blocked in DGKepsilon(-/-) mice, we postulate that the shortage of arachidonoyl-moiety inositol lipids and/or the messengers derived thereof is a key signaling event in epileptogenesis.
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Affiliation(s)
- Alberto Musto
- LSU Neuroscience Center of Excellence, Louisiana State University School of Medicine, Health Sciences Center, 2020 Gravier Street, New Orleans, LA 70112, U.S.A
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