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Galkina OV, Vetrovoy OV, Krasovskaya IE, Eschenko ND. Role of Lipids in Regulation of Neuroglial Interactions. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:337-352. [PMID: 37076281 DOI: 10.1134/s0006297923030045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 01/24/2023] [Accepted: 01/26/2023] [Indexed: 03/28/2023]
Abstract
Lipids comprise an extremely heterogeneous group of compounds that perform a wide variety of biological functions. Traditional view of lipids as important structural components of the cell and compounds playing a trophic role is currently being supplemented by information on the possible participation of lipids in signaling, not only intracellular, but also intercellular. The review article discusses current data on the role of lipids and their metabolites formed in glial cells (astrocytes, oligodendrocytes, microglia) in communication of these cells with neurons. In addition to metabolic transformations of lipids in each type of glial cells, special attention is paid to the lipid signal molecules (phosphatidic acid, arachidonic acid and its metabolites, cholesterol, etc.) and the possibility of their participation in realization of synaptic plasticity, as well as in other possible mechanisms associated with neuroplasticity. All these new data can significantly expand our knowledge about the regulatory functions of lipids in neuroglial relationships.
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Affiliation(s)
- Olga V Galkina
- Biochemistry Department, Faculty of Biology, Saint-Petersburg State University, St. Petersburg, 199034, Russia.
| | - Oleg V Vetrovoy
- Biochemistry Department, Faculty of Biology, Saint-Petersburg State University, St. Petersburg, 199034, Russia
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, 199034, Russia
| | - Irina E Krasovskaya
- Biochemistry Department, Faculty of Biology, Saint-Petersburg State University, St. Petersburg, 199034, Russia
| | - Nataliya D Eschenko
- Biochemistry Department, Faculty of Biology, Saint-Petersburg State University, St. Petersburg, 199034, Russia
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2
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Granade ME, Manigat LC, Lemke MC, Purow BW, Harris TE. Identification of ritanserin analogs that display DGK isoform specificity. Biochem Pharmacol 2022; 197:114908. [PMID: 34999054 PMCID: PMC8858877 DOI: 10.1016/j.bcp.2022.114908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/28/2021] [Accepted: 01/01/2022] [Indexed: 11/15/2022]
Abstract
The diacylglycerol kinase (DGK) family of lipid enzymes catalyzes the conversion of diacylglycerol (DAG) to phosphatidic acid (PA). Both DAG and PA are lipid signaling molecules that are of notable importance in regulating cell processes such as proliferation, apoptosis, and migration. There are ten mammalian DGK enzymes that appear to have distinct biological functions. DGKα has emerged as a promising therapeutic target in numerous cancers including glioblastoma (GBM) and melanoma as treatment with small molecule DGKα inhibitors results in reduced tumor sizes and prolonged survival. Importantly, DGKα has also been identified as an immune checkpoint due to its promotion of T cell anergy, and its inhibition has been shown to improve T cell activation. There are few small molecule DGKα inhibitors currently available, and the application of existing compounds to clinical settings is hindered by species-dependent variability in potency, as well as concerns regarding isotype specificity particularly amongst other type I DGKs. In order to resolve these issues, we have screened a library of compounds structurally analogous to the DGKα inhibitor, ritanserin, in an effort to identify more potent and specific alternatives. We identified two compounds that more potently and selectively inhibit DGKα, one of which (JNJ-3790339) demonstrates similar cytotoxicity in GBM and melanoma cells as ritanserin. Consistent with its inhibitor profile towards DGKα, JNJ-3790339 also demonstrated improved activation of T cells compared with ritanserin. Together our data support efforts to identify DGK isoform-selective inhibitors as a mechanism to produce pharmacologically relevant cancer therapies.
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Affiliation(s)
- Mitchell E Granade
- University of Virginia, School of Medicine, Department of Pharmacology, Charlottesville, VA, United States
| | - Laryssa C Manigat
- University of Virginia, School of Medicine, Department of Pathology, Charlottesville, VA, United States
| | - Michael C Lemke
- University of Virginia, School of Medicine, Department of Pharmacology, Charlottesville, VA, United States
| | - Benjamin W Purow
- University of Virginia, Department of Neurology, Division of Neuro-Oncology, Charlottesville, VA, United States.
| | - Thurl E Harris
- University of Virginia, School of Medicine, Department of Pharmacology, Charlottesville, VA, United States.
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3
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Potential role of diacylglycerol kinases in immune-mediated diseases. Clin Sci (Lond) 2021; 134:1637-1658. [PMID: 32608491 DOI: 10.1042/cs20200389] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/08/2020] [Accepted: 06/22/2020] [Indexed: 02/07/2023]
Abstract
The mechanism promoting exacerbated immune responses in allergy and autoimmunity as well as those blunting the immune control of cancer cells are of primary interest in medicine. Diacylglycerol kinases (DGKs) are key modulators of signal transduction, which blunt diacylglycerol (DAG) signals and produce phosphatidic acid (PA). By modulating lipid second messengers, DGK modulate the activity of downstream signaling proteins, vesicle trafficking and membrane shape. The biological role of the DGK α and ζ isoforms in immune cells differentiation and effector function was subjected to in deep investigations. DGK α and ζ resulted in negatively regulating synergistic way basal and receptor induced DAG signals in T cells as well as leukocytes. In this way, they contributed to keep under control the immune response but also downmodulate immune response against tumors. Alteration in DGKα activity is also implicated in the pathogenesis of genetic perturbations of the immune function such as the X-linked lymphoproliferative disease 1 and localized juvenile periodontitis. These findings suggested a participation of DGK to the pathogenetic mechanisms underlying several immune-mediated diseases and prompted several researches aiming to target DGK with pharmacologic and molecular strategies. Those findings are discussed inhere together with experimental applications in tumors as well as in other immune-mediated diseases such as asthma.
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4
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Beyond Lipid Signaling: Pleiotropic Effects of Diacylglycerol Kinases in Cellular Signaling. Int J Mol Sci 2020; 21:ijms21186861. [PMID: 32962151 PMCID: PMC7554708 DOI: 10.3390/ijms21186861] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/11/2020] [Accepted: 09/16/2020] [Indexed: 12/13/2022] Open
Abstract
The diacylglycerol kinase family, which can attenuate diacylglycerol signaling and activate phosphatidic acid signaling, regulates various signaling transductions in the mammalian cells. Studies on the regulation of diacylglycerol and phosphatidic acid levels by various enzymes, the identification and characterization of various diacylglycerol and phosphatidic acid-regulated proteins, and the overlap of different diacylglycerol and phosphatidic acid metabolic and signaling processes have revealed the complex and non-redundant roles of diacylglycerol kinases in regulating multiple biochemical and biological networks. In this review article, we summarized recent progress in the complex and non-redundant roles of diacylglycerol kinases, which is expected to aid in restoring dysregulated biochemical and biological networks in various pathological conditions at the bed side.
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Sawatani T, Kaneko YK, Ishikawa T. Dual effect of reduced type I diacylglycerol kinase activity on insulin secretion from MIN6 β-cells. J Pharmacol Sci 2019; 140:178-186. [PMID: 31279581 DOI: 10.1016/j.jphs.2019.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 05/03/2019] [Accepted: 06/11/2019] [Indexed: 02/07/2023] Open
Abstract
The role of type I diacylglycerol kinases (DGKs) in the regulation of insulin secretion was investigated in MIN6 β-cells. In intracellular Ca2+ concentration ([Ca2+]i) measurement experiments, 1 μM R59949, a type I DGK inhibitor, and 10 μM DiC8, a diacylglycerol (DAG) analog, amplified 22.2 mM glucose-induced [Ca2+]i oscillations in a protein kinase C (PKC)-dependent manner, whereas 10 μM R59949 and 100 μM DiC8 decreased [Ca2+]i independent of PKC. High concentrations of R59949 and DiC8 attenuated voltage-dependent Ca2+ channel currents. According to these results, 22.2 mM glucose-stimulated insulin secretion (GSIS) was potentiated by 1 μM R59949 but suppressed by 10 μM of the same. The DGKα inhibitor R59022 showed a similar dual effect. Conversely, DiC8 at 10 and 100 μM potentiated GSIS, although 100 μM DiC8 decreased [Ca2+]i. These results suggest that DAG accumulated through declined type I DGK activity shows a dual effect on insulin secretion depending on the degree of accumulation; a mild DAG accumulation induces a PKC-dependent stimulatory effect on insulin secretion, whereas an excessive DAG accumulation suppresses it in a PKC-independent manner, possibly via attenuation of VDCC activity.
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Affiliation(s)
- Toshiaki Sawatani
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka City, Shizuoka, 422-8526, Japan
| | - Yukiko K Kaneko
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka City, Shizuoka, 422-8526, Japan.
| | - Tomohisa Ishikawa
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka City, Shizuoka, 422-8526, Japan
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6
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Sano M, Kaneko MK, Kato Y. Epitope Mapping of Antidiacylglycerol Kinase α Monoclonal Antibody DaMab-2. Monoclon Antib Immunodiagn Immunother 2019; 38:8-11. [DOI: 10.1089/mab.2018.0047] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Affiliation(s)
- Masato Sano
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Mika K. Kaneko
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yukinari Kato
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Sendai, Japan
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Nakano T, Ogasawara S, Tanaka T, Hozumi Y, Mizuno S, Satoh E, Sakane F, Okada N, Taketomi A, Honma R, Nakamura T, Saidoh N, Yanaka M, Itai S, Handa S, Chang YW, Yamada S, Kaneko MK, Kato Y, Goto K. DaMab-2: Anti-Human DGKα Monoclonal Antibody for Immunocytochemistry. Monoclon Antib Immunodiagn Immunother 2017; 36:181-184. [DOI: 10.1089/mab.2017.0023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Affiliation(s)
- Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University Faculty of Medicine, Yamagata, Japan
| | - Satoshi Ogasawara
- Department of Regional Innovation, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Toshiaki Tanaka
- Department of Anatomy and Cell Biology, Yamagata University Faculty of Medicine, Yamagata, Japan
| | - Yasukazu Hozumi
- Department of Cell Biology and Morphology, Akita University Graduate School of Medicine, Akita, Japan
| | - Satoru Mizuno
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Eri Satoh
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Naoki Okada
- Department of Gastroenterological Surgery I, Graduate School of Medicine, Hokkaido University, Hokkaido, Japan
| | - Akinobu Taketomi
- Department of Gastroenterological Surgery I, Graduate School of Medicine, Hokkaido University, Hokkaido, Japan
| | - Ryusuke Honma
- Department of Regional Innovation, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Takuro Nakamura
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Noriko Saidoh
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Miyuki Yanaka
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Shunsuke Itai
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Saori Handa
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Yao-Wen Chang
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Shinji Yamada
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Mika K. Kaneko
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Yukinari Kato
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Miyagi, Japan
- New Industry Creation Hatchery Center, Tohoku University, Miyagi, Japan
| | - Kaoru Goto
- Department of Anatomy and Cell Biology, Yamagata University Faculty of Medicine, Yamagata, Japan
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8
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Modulated DISP3/PTCHD2 expression influences neural stem cell fate decisions. Sci Rep 2017; 7:41597. [PMID: 28134287 PMCID: PMC5278513 DOI: 10.1038/srep41597] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 12/21/2016] [Indexed: 12/17/2022] Open
Abstract
Neural stem cells (NSCs) are defined by their dual ability to self-renew through mitotic cell division or differentiate into the varied neural cell types of the CNS. DISP3/PTCHD2 is a sterol-sensing domain-containing protein, highly expressed in neural tissues, whose expression is regulated by thyroid hormone. In the present study, we used a mouse NSC line to investigate what effect DISP3 may have on the self-renewal and/or differentiation potential of the cells. We demonstrated that NSC differentiation triggered significant reduction in DISP3 expression in the resulting astrocytes, neurons and oligodendrocytes. Moreover, when DISP3 expression was disrupted, the NSC "stemness" was suppressed, leading to a larger population of cells undergoing spontaneous neuronal differentiation. Conversely, overexpression of DISP3 resulted in increased NSC proliferation. When NSCs were cultured under differentiation conditions, we observed that the lack of DISP3 augmented the number of NSCs differentiating into each of the neural cell lineages and that neuronal morphology was altered. In contrast, DISP3 overexpression resulted in impaired cell differentiation. Taken together, our findings imply that DISP3 may help dictate the NSC cell fate to either undergo self-renewal or switch to the terminal differentiation cell program.
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Nakano T, Matsui H, Tanaka T, Hozumi Y, Iseki K, Kawamae K, Goto K. Arachidonoyl-Specific Diacylglycerol Kinase ε and the Endoplasmic Reticulum. Front Cell Dev Biol 2016; 4:132. [PMID: 27917381 PMCID: PMC5114243 DOI: 10.3389/fcell.2016.00132] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 10/31/2016] [Indexed: 01/22/2023] Open
Abstract
The endoplasmic reticulum (ER) comprises an interconnected membrane network, which is made up of lipid bilayer and associated proteins. This organelle plays a central role in the protein synthesis and sorting. In addition, it represents the synthetic machinery of phospholipids, the major constituents of the biological membrane. In this process, phosphatidic acid (PA) serves as a precursor of all phospholipids, suggesting that PA synthetic activity is closely associated with the ER function. One enzyme responsible for PA synthesis is diacylglycerol kinase (DGK) that phosphorylates diacylglycerol (DG) to PA. DGK is composed of a family of enzymes with distinct features assigned to each isozyme in terms of structure, enzymology, and subcellular localization. Of DGKs, DGKε uniquely exhibits substrate specificity toward arachidonate-containing DG and is shown to reside in the ER. Arachidonic acid, a precursor of bioactive eicosanoids, is usually acylated at the sn-2 position of phospholipids, being especially enriched in phosphoinositide. In this review, we focus on arachidonoyl-specific DGKε with respect to the historical context, molecular basis of the substrate specificity and ER-targeting, and functional implications in the ER.
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Affiliation(s)
- Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine Yamagata, Japan
| | - Hirooki Matsui
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine Yamagata, Japan
| | - Toshiaki Tanaka
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine Yamagata, Japan
| | - Yasukazu Hozumi
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine Yamagata, Japan
| | - Ken Iseki
- Department of Emergency and Critical Care Medicine, Fukushima Medical University School of Medicine Fukushima, Japan
| | - Kaneyuki Kawamae
- Department of Anesthesiology, Yamagata University School of Medicine Yamagata, Japan
| | - Kaoru Goto
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine Yamagata, Japan
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10
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Boroda S, Niccum M, Raje V, Purow BW, Harris TE. Dual activities of ritanserin and R59022 as DGKα inhibitors and serotonin receptor antagonists. Biochem Pharmacol 2016; 123:29-39. [PMID: 27974147 DOI: 10.1016/j.bcp.2016.10.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 10/25/2016] [Indexed: 11/17/2022]
Abstract
Diacylglycerol kinase alpha (DGKα) catalyzes the conversion of diacylglycerol (DAG) to phosphatidic acid (PA). Recently, DGKα was identified as a therapeutic target in various cancers, as well as in immunotherapy. Application of small-molecule DGK inhibitors, R59022 and R59949, induces cancer cell death in vitro and in vivo. The pharmacokinetics of these compounds in mice, however, are poor. Thus, there is a need to discover additional DGK inhibitors not only to validate these enzymes as targets in oncology, but also to achieve a better understanding of their biology. In the present study, we investigate the activity of ritanserin, a compound structurally similar to R59022, against DGKα. Ritanserin, originally characterized as a serotonin (5-HT) receptor (5-HTR) antagonist, underwent clinical trials as a potential medicine for the treatment of schizophrenia and substance dependence. We document herein that ritanserin attenuates DGKα kinase activity while increasing the enzyme's affinity for ATP in vitro. In addition, R59022 and ritanserin function as DGKα inhibitors in cultured cells and activate protein kinase C (PKC). While recognizing that ritanserin attenuates DGK activity, we also find that R59022 and R59949 are 5-HTR antagonists. In conclusion, ritanserin, R59022 and R59949 are combined pharmacological inhibitors of DGKα and 5-HTRs in vitro.
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Affiliation(s)
- Salome Boroda
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Maria Niccum
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Vidisha Raje
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Benjamin W Purow
- Department of Neurology, University of Virginia School of Medicine, Charlottesville, VA 22903, USA.
| | - Thurl E Harris
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22903, USA.
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11
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Distinct 1-monoacylglycerol and 2-monoacylglycerol kinase activities of diacylglycerol kinase isozymes. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:1170-1176. [PMID: 27346717 DOI: 10.1016/j.bbapap.2016.06.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 06/15/2016] [Accepted: 06/22/2016] [Indexed: 02/02/2023]
Abstract
Diacylglycerol kinase (DGK) consists of ten isozymes and is involved in a wide variety of patho-physiological events. However, the enzymological properties of DGKs have not been fully understood. In this study, we performed a comprehensive analysis on the 1-monoacylglycerol kinase (MGK) and 2-MGK activities of ten DGK isozymes. We revealed that type I (α, β and γ), type II (δ, η and κ) and type III (ε) DGKs have 7.9-19.2% 2-MGK activity compared to their DGK activities, whereas their 1-MGK activities were <3.0%. Both the 1-MGK and 2-MGK activities of the type IV DGKs (ζ and ι) were <1% relative to their DGK activities. Intriguingly, type V DGKθ has approximately 6% 1-MGK activity and <2% 2-MGK activity compared to its DGK activity. Purified DGKθ exhibited the same results, indicating that its 1-MGK activity is intrinsic. Therefore, DGK isozymes are categorized into three types with respect to their 1-MGK and 2-MGK activities: those having (1) 2-MGK activity relatively stronger than their 1-MGK activity (types I-III), (2) only negligible 1-MGK and 2-MGK activities (type IV), and (3) 1-MGK activity stronger than its 2-MGK activity (type V). The 1-MGK activity of DGKθ and the 2-MGK activity of DGKα were stronger than those of the acylglycerol kinase reported as 1-MGK and 2-MGK to date. The presence or absence of 1-MGK and 2-MGK activities may be essential to the patho-physiological functions of each DGK isozyme.
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12
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Expression and localization of the diacylglycerol kinase family and of phosphoinositide signaling molecules in adrenal gland. Cell Tissue Res 2015; 362:295-305. [PMID: 26003177 DOI: 10.1007/s00441-015-2199-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 04/13/2015] [Indexed: 10/23/2022]
Abstract
Adrenal glands play a central role in the secretion of steroid hormones and catecholamines. Previous studies have revealed that molecules engaged in phosphoinositide (PI) turnover are expressed in the adrenal gland, suggesting the importance of PI signaling in adrenal signal transduction. Diacylglycerol kinase (DGK) catalyzes the phosphorylation of diacylglycerol (DG), a major second messenger in the PI signaling cascade. The DGK family is expressed in distinct patterns in endocrine organs at the mRNA and protein levels. Nevertheless, little is known about the characteristics and morphological aspects of DGKs in the adrenal gland. We have performed immunohistochemical analyses to investigate the expression and localization of DGK isozymes, together with PI signaling molecules, in the adrenal gland at the protein level. Our results show that the DGK family and a set of PI signaling molecules are expressed intensely in zona glomerulosa cells and medullary chromaffin cells in the adrenal gland. In adrenal cells, DGKγ localizes to the Golgi complex, DGKε to the plasma membrane, and DGKζ to the nucleus. These findings show the distinct expression and subcellular localization of DGK isozymes and PI signaling molecules in the adrenal gland, suggesting that each DGK isozyme has a role in signal transduction in adrenal cells, especially in the zona glomerulosa and medulla.
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13
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Roles of lipid-modulating enzymes diacylglycerol kinase and cyclooxygenase under pathophysiological conditions. Anat Sci Int 2014; 90:22-32. [PMID: 25471593 DOI: 10.1007/s12565-014-0265-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 11/17/2014] [Indexed: 10/24/2022]
Abstract
Lipid not only represents a constituent of the plasma membrane, but also plays a pivotal role in intracellular signaling. Lipid-mediated signaling system is strictly regulated by several enzymes, which act at various steps of the lipid metabolism. Under pathological conditions, prolonged or insufficient activation of this system results in dysregulated signaling, leading to diseases such as cancer or metabolic syndrome. Of the lipid-modulating enzymes, diacylglycerol kinase (DGK) and cyclooxygenase (COX) are intimately involved in the signaling system. DGK consists of a family of enzymes that phosphorylate a second messenger diacylglycerol (DG) to produce phosphatidic acid (PA). Both DG and PA are known to activate signaling molecules such as protein kinase C. COX catalyzes the committed step in prostanoid biosynthesis, which involves the metabolism of arachidonic acid to produce prostaglandins. Previous studies have shown that the DGK and COX are engaged in a number of pathological conditions. This review summarizes the functional implications of these two enzymes in ischemia, liver regeneration, vascular events, diabetes, cancer and inflammation.
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14
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Tsuchiya R, Tanaka T, Hozumi Y, Nakano T, Okada M, Topham MK, Iino M, Goto K. Downregulation of diacylglycerol kinase ζ enhances activation of cytokine-induced NF-κB signaling pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:361-9. [PMID: 25450975 DOI: 10.1016/j.bbamcr.2014.11.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/31/2014] [Accepted: 11/10/2014] [Indexed: 01/06/2023]
Abstract
The transcription factor NF-κB family serves as a key component of many pathophysiological events such as innate and adaptive immune response, inflammation, apoptosis, and oncogenesis. Various cell signals trigger activation of the regulatory mechanisms of NF-κB, resulting in its nuclear translocation and transcriptional initiation. The diacylglycerol kinase (DGK) family, a lipid second messenger-metabolizing enzyme in phosphoinositide signaling, is shown to regulate widely various cellular processes. Results of recent studies suggest that one family member, DGKζ, is closely involved in immune and inflammatory responses. Nevertheless, little is known about the regulatory mechanism of DGKζ on NF-κB pathway in cytokine-induced inflammatory signaling. This study shows that siRNA-mediated DGKζ knockdown in HeLa cells facilitates degradation of IκB, followed by nuclear translocation of NF-κB p65 subunit. In addition, DGKζ-deficient MEFs show upregulation of p65 subunit phosphorylation at Serine 468 and 536 and its interaction with CBP transcriptional coactivator upon TNF-α stimulation. These modifications of p65 subunit might engender enhanced NF-κB transcriptional reporter assay of DGKζ knockdown cells. These findings provide further insight into the regulatory mechanisms of cytokine-induced NF-κB activation.
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Affiliation(s)
- Rieko Tsuchiya
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan; Department of Dentistry, Oral and Maxillofacial Plastic and Reconstructive Surgery, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Toshiaki Tanaka
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Yasukazu Hozumi
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Masashi Okada
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Matthew K Topham
- Huntsman Cancer Institute, Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Mitsuyoshi Iino
- Department of Dentistry, Oral and Maxillofacial Plastic and Reconstructive Surgery, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Kaoru Goto
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan.
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15
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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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Yamamoto M, Tanaka T, Hozumi Y, Saino-Saito S, Nakano T, Tajima K, Kato T, Goto K. Expression of mRNAs for the diacylglycerol kinase family in immune cells during an inflammatory reaction. Biomed Res 2014; 35:61-8. [PMID: 24573202 DOI: 10.2220/biomedres.35.61] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Phosphoinositide metabolism is intimately involved in cellular signal transduction. In response to extracellular stimuli, it generates diacylglycerol (DG), which serves as a lipid second messenger molecule to activate various proteins in various organs under pathophysiological conditions. Diacylglycerolkinase (DGK) constitutes an enzyme family that catalyzes conversion of DG to phosphatidic acid. It is therefore regarded as a regulator of the DG signal. Previous studies have revealed the critical role of α and ζ types of DGK in T cell functions. Nevertheless, little is known about the expression patterns of the DGK family in immune cells of various kinds. After examination of the expression profile of DGK isozymes in immune cells that are isolated from human blood, we investigated whether their mRNA expression levels would be changed during an inflammatory reaction. Results showed that DGK isozyme mRNAs are widely expressed in immune cells, except for DGKβ and DGKι. During an inflammatory reaction, DGKε mRNA was increased transiently in the initial phase (20-40 min) of stimulation with both LPS and IL-2 in T cell-derived HUT-102 cells and macrophage-derived RAW264 cells. At the organismal level, an intraperitoneal injection of LPS also induced upregulation of DGKε mRNA in the spleen in a similar,but not identical, manner. These results suggest that DGKε is involved in inflammatory processes of the cellular immune system.
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Affiliation(s)
- Masakazu Yamamoto
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-nishi 2-2-2, Yamagata 990-9585, Japan
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17
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Sakiyama S, Usuki T, Sakai H, Sakane F. Regulation of diacylglycerol kinase δ2 expression in C2C12 skeletal muscle cells by free fatty acids. Lipids 2014; 49:633-40. [PMID: 24852321 DOI: 10.1007/s11745-014-3912-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Accepted: 05/02/2014] [Indexed: 12/14/2022]
Abstract
Decreased expression of diacylglycerol kinase (DGK) δ in skeletal muscles is closely related to the pathogenesis of type 2 diabetes. However, the regulation of DGKδ expression is not well understood. In this study, we found that myristic acid (14:0) significantly increased DGKδ2 protein expression in a dose-dependent manner (EC(50) = 0.16 mM) in mouse C2C12 myotubes. In contrast, oleic [18:1(n-9)], eicosenoic [20:1(n-9)] and erucic [22:1(n-9)] acids markedly decreased DGKδ2 expression. Myristic acid slowly enhanced DGKδ2 expression at the transcription level. Therefore, DGKδ2 expression is positively regulated by the relatively short-chain saturated fatty acid myristic acid but attenuated by n-9 monounsaturated fatty acids.
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Affiliation(s)
- Shizuka Sakiyama
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
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18
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Yamamoto T, Sakai H, Sakane F. EF-hand motifs of diacylglycerol kinase α interact intra-molecularly with its C1 domains. FEBS Open Bio 2014; 4:387-92. [PMID: 24918053 PMCID: PMC4050180 DOI: 10.1016/j.fob.2014.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 04/14/2014] [Accepted: 04/15/2014] [Indexed: 02/02/2023] Open
Abstract
We revealed the intra-molecular interaction of DGKα. The EF-hand motifs of DGKα directly binds to its C1 domains. The intra-molecular interaction was negatively regulated by Ca2+. The intra-molecular interaction is important for the activation mechanism of DGKα.
Diacylglycerol kinase (DGK) α, which is activated by Ca2+, contains a recoverin homology (RVH) domain, tandem repeats of two Ca2+-binding EF-hand motifs, two cysteine-rich C1 domains and the catalytic domain. We previously found that a DGKα mutant lacking the RVH domain and EF-hands was constitutively active and that the N-terminal region of DGKα, consisting of the RVH domain and EF-hand motifs, interacted intra-molecularly with the C-terminal region containing the C1 and catalytic domains. In this study, we narrowed down the interaction regions of DGKα. At the C-terminal region, the C1 domains are responsible for the intra-molecular interaction. At the N-terminal region, the EF-hand motifs mainly contribute to the interaction. Moreover, using highly purified EF-hand motifs and C1 domains, we demonstrate that they directly bind to each other. The co-precipitation of these two domains was clearly attenuated by the addition of Ca2+. These results indicate that the Ca2+-induced dissociation of the intra-molecular interaction between the EF-hand motifs and the C1 domains of DGKα is the key event that regulates the activity of the enzyme.
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Key Words
- C1 domain
- C1Ds, C1 domains
- CR, catalytic region
- Calcium
- DG, diacylglycerol
- DGK, diacylglycerol kinase
- Diacylglycerol kinase
- EF-hand
- EFHs, EF-hand motifs
- EGFP, enhanced green fluorescence protein
- EGTA, ethylene glycol tetraacetic acid
- GST, glutathione S-transferase
- Intra-molecular interaction
- RVH, recoverin homology
- RVHD, RVH domain
- TF, trigger factor
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Affiliation(s)
- Tatsuya Yamamoto
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Hiromichi Sakai
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
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Shirai Y, Saito N. Diacylglycerol kinase as a possible therapeutic target for neuronal diseases. J Biomed Sci 2014; 21:28. [PMID: 24708409 PMCID: PMC4005014 DOI: 10.1186/1423-0127-21-28] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 03/05/2014] [Indexed: 02/02/2023] Open
Abstract
Diacylglycerol kinase (DGK) is a lipid kinase converting diacylglycerol to phosphatidic acid, and regulates many enzymes including protein kinase C, phosphatidylinositol 4-phosphate 5-kinase, and mTOR. To date, ten mammalian DGK subtypes have been cloned and divided into five groups, and they show subtype-specific tissue distribution. Therefore, each DGK subtype is thought to be involved in respective cellular responses by regulating balance of the two lipid messengers, diacylglycerol and phosphatidic acid. Indeed, the recent researches using DGK knockout mice have clearly demonstrated the importance of DGK in the immune system and its pathophysiological roles in heart and insulin resistance in diabetes. Especially, most subtypes show high expression in brain with subtype specific regional distribution, suggesting that each subtype has important and unique functions in brain. Recently, neuronal functions of some DGK subtypes have accumulated. Here, we introduce DGKs with their structural motifs, summarize the enzymatic properties and neuronal functions, and discuss the possibility of DGKs as a therapeutic target of the neuronal diseases.
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Affiliation(s)
- Yasuhito Shirai
- Laboratory of Chemistry and Utilization of Animal Production Resources, Applied Chemistry in Bioscience Division, Graduate School of Agricultural Science, Kobe University, Rokkodai-cho 1-1, Nada-ku, 657-8501 Kobe, Japan.
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20
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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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Kurohane Kaneko Y, Kobayashi Y, Motoki K, Nakata K, Miyagawa S, Yamamoto M, Hayashi D, Shirai Y, Sakane F, Ishikawa T. Depression of type I diacylglycerol kinases in pancreatic β-cells from male mice results in impaired insulin secretion. Endocrinology 2013; 154:4089-98. [PMID: 24035999 DOI: 10.1210/en.2013-1356] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Diacylglycerol kinase (DGK) catalyzes the conversion of diacylglycerol (DAG) to phosphatidic acid. This study investigated the expression and function of DGK in pancreatic β-cells. mRNA expression of type I DGK isoforms (α, β, γ) was detected in mouse pancreatic islets and the β-cell line MIN6. Protein expression of DGKα and DGKγ was also detected in mouse β-cells and MIN6 cells. The type I DGK inhibitor R59949 inhibited high K(+)- and glucose-induced insulin secretion in MIN6 cells. Moreover, single knockdown of DGKα or DGKγ by small interfering RNA slightly but significantly decreased glucose- and high K(+)-induced insulin secretions, and the double knockdown further decreased them to the levels comparable with those induced by R59949. R59949 and DiC8, a membrane permeable DAG analog, decreased intracellular Ca(2+) concentration elevated by glucose and high K(+) in MIN6 cells. Real-time imaging in MIN6 cells expressing green fluorescent protein-tagged DGKα or DGKγ showed that the DGK activator phorbol 12-myristate 13-acetate rapidly induced translocation of DGKγ to the plasma membrane, whereas high K(+) slowly translocated DGKα and DGKγ to the plasma membrane. R59949 increased the DAG content in MIN6 cells when stimulated with high KCl, whereas it did not increase the DAG content but decreased the phosphatidic acid content when stimulated with high glucose. Finally, R59949 was confirmed to inhibit high K(+)-induced insulin secretion from mouse islets and glucose-induced insulin secretion from rat islets. These results suggest that DGKα and DGKγ are present in β-cells and that the depression of these DGKs causes a decrease in intracellular Ca(2+) concentration, thereby reducing insulin secretion.
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22
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Abstract
Diacylglycerol (DAG), a second messenger generated by phospholipase Cγ1 activity upon engagement of a T-cell receptor, triggers several signaling cascades that play important roles in T cell development and function. A family of enzymes called DAG kinases (DGKs) catalyzes the phosphorylation of DAG to phosphatidic acid, acting as a braking mechanism that terminates DAG-mediated signals. Two DGK isoforms, α and ζ, are expressed predominantly in T cells and synergistically regulate the development of both conventional αβ T cells and invariant natural killer T cells in the thymus. In mature T cells, the activity of these DGK isoforms aids in the maintenance of self-tolerance by preventing T-cell hyperactivation upon T cell receptor stimulation and by promoting T-cell anergy. In CD8 cells, reduced DGK activity is associated with enhanced primary responses against viruses and tumors. Recent work also has established an important role for DGK activity at the immune synapse and identified partners that modulate DGK function. In addition, emerging evidence points to previously unappreciated roles for DGK function in directional secretion and T-cell adhesion. This review describes the multitude of roles played by DGKs in T cell development and function and emphasizes recent advances in the field.
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Affiliation(s)
- Sruti Krishna
- Department of Pediatrics, Division of Allergy and Immunology and Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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23
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Hozumi Y, Watanabe M, Goto K. Signaling cascade of diacylglycerol kinase β in the pituitary intermediate lobe: dopamine D2 receptor/phospholipase Cβ4/diacylglycerol kinase β/protein kinase Cα. J Histochem Cytochem 2013; 58:119-29. [PMID: 19826069 DOI: 10.1369/jhc.2009.954347] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Accepted: 09/21/2009] [Indexed: 02/05/2023] Open
Abstract
The pituitary gland dynamically changes its hormone output under various pathophysiological conditions. One of the pathways implicated in the regulatory mechanism of this gland is a dopaminergic system that operates the phosphoinositide (PI) cycle to transmit downstream signal through second messengers. We have previously shown that diacylglycerol kinase β (DGKβ) is coexpressed with dopamine D1 and D2 receptors in medium spiny neurons of the striatum, suggesting a plausible implication of DGKβ in dopaminergic transmission. However, it remains elusive whether DGKβ is involved in the dopaminergic system in the pituitary gland. The aim of this study is to investigate the expression and localization of DGK in the pituitary gland, together with the molecular components involved in the PI signaling cascade, including dopamine receptors, phospholipase C (PLC), and a major downstream molecule, protein kinase C (PKC). Here we show that DGKβ and the dopamine D2 receptor are coexpressed in the intermediate lobe and localize to the plasma membrane side by side. In addition, we reveal that PLCβ4 and PKCα are the subtypes expressed in the intermediate lobe among those families. These findings will substantiate and further extend our understanding of the molecular-anatomical pathway of PI signaling and the functional roles of DGK in the pituitary intermediate lobe.
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Affiliation(s)
- Yasukazu Hozumi
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan.
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24
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Hozumi Y, Matsui H, Sakane F, Watanabe M, Goto K. Distinct expression and localization of diacylglycerol kinase isozymes in rat retina. J Histochem Cytochem 2013; 61:462-76. [PMID: 23467923 DOI: 10.1369/0022155413483574] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Recent studies have revealed that phosphoinositide (PI) signaling molecules are expressed in mammalian retinas, suggesting their importance in its signal transduction. We previously showed that diacylglycerol kinase (DGK) isozymes are expressed in distinct patterns in rat retina at the mRNA level. However, little is known about the nature and morphological aspects of DGKs in the retina. For this study, we performed immunohistochemical analyses to investigate in the retina the expression and localization of DGK isozymes at the protein level. Here, we show that both DGKβ and DGKι localize in the outer plexiform layer, within which photoreceptor cells make contact with bipolar and horizontal cells. These isozymes exhibit distinct subcellular localization patterns: DGKι localizes to the synaptic area of bipolar cells in a punctate manner, whereas DGKβ distributes diffusely in the subsynaptic and dendritic regions of bipolar and horizontal cells. However, punctate labeling for DGKε is evident in the outer limiting membrane. DGKζ and DGKα localize predominantly to the nucleus of ganglion cells. These findings show distinct expression and localization of DGK isozymes in the retina, suggesting a different role of each isozyme.
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Affiliation(s)
- Yasukazu Hozumi
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata, Japan.
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25
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Takahashi M, Yamamoto T, Sakai H, Sakane F. Calcium negatively regulates an intramolecular interaction between the N-terminal recoverin homology and EF-hand motif domains and the C-terminal C1 and catalytic domains of diacylglycerol kinase α. Biochem Biophys Res Commun 2012; 423:571-6. [PMID: 22695121 DOI: 10.1016/j.bbrc.2012.06.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 06/02/2012] [Indexed: 12/25/2022]
Abstract
The type I diacylglycerol kinase (DGK) isozymes (α, β and γ) contain a shared recoverin homology (RVH) domain, a tandem repeat of Ca2+-binding EF-hand motifs, two cysteine-rich C1 domains, and the catalytic domain. We previously reported that a DGKα mutant lacking the RVH domain and EF-hands was constitutively active, implying that the N-terminal region (NTR) of DGKα, consisting of the RVH domain and EF-hand motifs, intramolecularly interacts with and masks the activity of the C-terminal region (CTR), containing the C1 and catalytic domains. In this study, we demonstrate that a glutathione S-transferase (GST)-fused DGKα-NTR construct physically binds to a green fluorescent protein (GFP)-fused DGKα-CTR construct. Moreover, co-precipitation of GFP-DGKα-CTR with GST-DGKα-NTR was clearly attenuated by the addition of 1 μM Ca2+. This result indicates that Ca2+ induces dissociation of the physical interaction between DGKα-NTR and DGKα-CTR. In addition to previously reported calcium-dependent changes in the hydrophobicity and net surface charge, Ca2+ also appeared to induce a decrease in the α-helical content of DGKα-NTR. These results suggest that Ca2+-induced conformational changes in the NTR release the intramolecular association between the NTR and the CTR of DGKα.
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Affiliation(s)
- Masato Takahashi
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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26
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Involvement of diacylglycerol kinase γ in modulation of iNOS synthesis in Golgi apparatus of vascular endothelial cells. Naunyn Schmiedebergs Arch Pharmacol 2012; 385:787-95. [PMID: 22627682 DOI: 10.1007/s00210-012-0760-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 05/04/2012] [Indexed: 10/27/2022]
Abstract
The aim of this study was to clarify the role of diacylglycerol kinase (DGK)γ in vascular endothelial cells. The mRNA and protein expression of DGKγ and inducible nitric oxide synthase (iNOS) in rat aortic endothelial cells (RAECs) were investigated using RT-PCR, immunocytochemical, and immunoblot analyses. In RAECs, immunoreactivity of DGKγ was detected in the cytoplasm as a tubular or reticular structure. DGKγ immunoreactivity colocalized with those for GM130 and Golgin 97 but not with that for protein disulfide isomerase (PDI). In the presence of brefeldin A, DGKγ immunoreactivity was markedly decreased and displayed an aggregation-like pattern. After treatment of RAECs with nocodazole, DGKγ immunoreactivity was detected in Golgi stacks, which were severely segmented and appeared in vesicular shape. Stimulation with IL-1β increased mRNA expression of DGKγ, which was strongly attenuated by SB203580, a p38 MAPK inhibitor. IL-1β also induced expression of iNOS, which was observed as a tubular structure, and this distribution coincided with DGKγ immunoreactivity. Brefeldin A reduced both iNOS immunoreactivity and DGKγ immunoreactivity. iNOS expression was impaired by DGK inhibitors, R59022 and R59949. These results suggest that DGKγ is upregulated by IL-1β through the p38 MAPK pathway and may be involved in protein trafficking of iNOS in vascular endothelial cells.
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Hozumi Y, Goto K. Diacylglycerol kinase β in neurons: functional implications at the synapse and in disease. Adv Biol Regul 2012; 52:315-25. [PMID: 22781745 DOI: 10.1016/j.jbior.2012.03.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 03/23/2012] [Indexed: 11/18/2022]
Abstract
Phosphoinositide cycle plays a pivotal role in neuronal signal transduction. In this cycle, diacylglycerol kinase (DGK) phosphorylates diacylglycerol (DG) to yield phosphatidic acid (PA). DG and PA acts as important second messengers that regulate distinct cascade of cellular events. Previous studies have disclosed that DGK consists of a family of isozymes that differ in their structure, enzymatic property, gene expression, subcellular localization, and binding partner. Intriguingly, most if not all DGK isozymes are abundantly expressed in the brain, suggesting important roles of this enzyme family in brain function. Of DGKs, DGKβ was the first enzyme identified as being expressed in a neuronal population in the brain. This review focuses on recent findings of DGKβ at the molecular, cellular, and organismal levels together with pathological implications in brain function and disease.
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Affiliation(s)
- Yasukazu Hozumi
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-nishi 2-2-2, Yamagata 990-9585, Japan.
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28
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Shin J, O'Brien TF, Grayson JM, Zhong XP. Differential regulation of primary and memory CD8 T cell immune responses by diacylglycerol kinases. THE JOURNAL OF IMMUNOLOGY 2012; 188:2111-7. [PMID: 22271650 DOI: 10.4049/jimmunol.1102265] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The manipulation of signals downstream of the TCR can have profound consequences for T cell development, function, and homeostasis. Diacylglycerol (DAG) produced after TCR stimulation functions as a secondary messenger and mediates the signaling to Ras-MEK-Erk and NF-κB pathways in T cells. DAG kinases (DGKs) convert DAG into phosphatidic acid, resulting in termination of DAG signaling. In this study, we demonstrate that DAG metabolism by DGKs can serve a crucial function in viral clearance upon lymphocytic choriomeningitis virus infection. Ag-specific CD8(+) T cells from DGKα(-/-) and DGKζ(-/-) mice show enhanced expansion and increased cytokine production after lymphocytic choriomeningitis virus infection, yet DGK-deficient memory CD8(+) T cells exhibit impaired expansion after rechallenge. Thus, DGK activity plays opposing roles in the expansion of CD8(+) T cells during the primary and memory phases of the immune response, whereas consistently inhibiting antiviral cytokine production.
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Affiliation(s)
- Jinwook Shin
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA
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29
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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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30
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Nakano T, Hozumi Y, Iwazaki K, Okumoto K, Iseki K, Saito T, Kawata S, Wakabayashi I, Goto K. Altered expression of diacylglycerol kinase isozymes in regenerating liver. J Histochem Cytochem 2011; 60:130-8. [PMID: 22205637 DOI: 10.1369/0022155411429154] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The liver possesses the capacity to restore its function and mass after injury. Liver regeneration is controlled through complicated mechanisms, in which the phosphoinositide (PI) cycle is shown to be activated in hepatocytes. Using a rat partial hepatectomy (PH) model, the authors investigated the expression of the diacylglycerol kinase (DGK) family, a key enzyme in the PI cycle, which metabolizes a lipid second-messenger diacylglycerol (DG). RT-PCR analysis shows that DGKζ and DGKα are the major isozymes in the liver. Results showed that in the process of regeneration, the DGKζ protein, which is detected in the nucleus of a small population of hepatocytes in normal liver, is significantly increased in almost all hepatocytes. However, the mRNA levels remain largely unchanged. Double labeling with bromodeoxyuridine (BrdU), an S phase marker, reveals that DGKζ is expressed independently of DNA synthesis or cell proliferation. However, DGKα protein localizes to the cytoplasm in normal and regenerating livers, but immunoblot analysis reveals that the expected (80 kDa) and the lower (70 kDa) bands are detected in normal liver, whereas at day 10 after PH, the expected band is solely recognized, showing a different processing pattern of DGKα in liver regeneration. These results suggest that DGKζ and DGKα are involved, respectively, in the nucleus and the cytoplasm of hepatocytes in regenerating liver.
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Affiliation(s)
- Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata, Japan
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31
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Matsubara T, Ikeda M, Kiso Y, Sakuma M, Yoshino KI, Sakane F, Merida I, Saito N, Shirai Y. c-Abl tyrosine kinase regulates serum-induced nuclear export of diacylglycerol kinase α by phosphorylation at Tyr-218. J Biol Chem 2011; 287:5507-17. [PMID: 22199356 DOI: 10.1074/jbc.m111.296897] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
c-Abl is a tyrosine kinase involved in many cellular processes, including cell cycle control and proliferation. However, little is known about its substrates. Here, we show that c-Abl directly phosphorylates diacylglycerol kinase α (DGKα), an important regulator of many cellular events through its conversion of diacylglycerol to phosphatidic acid. We found that DGKα was transported from the cytoplasm to the nucleus in response to serum starvation, and serum restoration induced the nuclear export of the enzyme to the cytoplasm. This serum-induced export involves two tyrosine kinases, c-Src and c-Abl. The latter, c-Abl, is activated by c-Src, phosphorylates DGKα, and shuttles between the nucleus and the cytoplasm in a direction opposite to that of DGKα in response to serum restoration. Moreover, an in vitro phosphorylation assay using purified mutants of DGKα identified Tyr-218 as a site of phosphorylation by c-Abl. We confirmed these results for endogenous DGKα using an antibody specific for phospho-Tyr-218, and this phosphorylation was necessary for the serum-induced export of DGKα. These results demonstrate that the nucleo-cytoplasmic shuttling of DGKα is orchestrated by tyrosine phosphorylation by the Src-activated tyrosine kinase c-Abl and that this phosphorylation is important for regulating the function of cytoplasmic and/or nuclear DGKα.
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Affiliation(s)
- Takehiro Matsubara
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Rokkodai-cho 1-1, Nada-ku, Kobe 657-8501, Japan
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32
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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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Mérida I, Avila-Flores A, García J, Merino E, Almena M, Torres-Ayuso P. Diacylglycerol kinase alpha, from negative modulation of T cell activation to control of cancer progression. ACTA ACUST UNITED AC 2009; 49:174-88. [PMID: 19534031 DOI: 10.1016/j.advenzreg.2009.01.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Isabel Mérida
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Darwin 3, Campus de Cantoblanco, E-28049 Madrid, Spain.
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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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Localization of diacylglycerol kinase epsilon on stress fibers in vascular smooth muscle cells. Cell Tissue Res 2009; 337:167-75. [PMID: 19421779 DOI: 10.1007/s00441-009-0795-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2008] [Accepted: 03/17/2009] [Indexed: 10/20/2022]
Abstract
The expression pattern of diacylglycerol kinase (DGK) and the biological significance of DGKepsilon in vascular smooth muscle cells were investigated. mRNA expression for DGKalpha, DGKepsilon, and DGKzeta was detected in isolated rat aortic smooth muscle cells (RASMCs) and A7r5 cells by reverse transcription with polymerase chain reaction analysis. An immunocytochemical study revealed intense DGKepsilon in a filamentous pattern, parallel to the long axis of cell, and on actin stress fibers as shown by double-staining with fluorescent phalloidin. DGKalpha was detected sparsely in the cytoplasm and nucleus, and DGKzeta was observed as a granular pattern in the nucleus. In order to elucidate the functional significance of DGKepsilon, its immunoreactivity was examined in RASMCs incubated with serotonin, a vasoconstrictive agonist. When RASMCs were stimulated with serotonin, the cells lost their polarization and shortened, i.e., contracted. In RASMCs contracted by serotonin, DGKepsilon was detected diffusely in the cytoplasm without a filamentous stress fiber pattern. Protein and mRNA expression of DGKepsilon in RASMCs was significantly increased by stimulation with serotonin. Inhibition of Rho-associated kinases by Y-27632 or inhibition of actin polymerization by cytochalasin B resulted in a decrease in the intensity of DGKepsilon immunoreactivity on stress fibers. The results suggest that DGKepsilon interacts with actin stress fibers and is involved in their stability in vascular smooth muscle cells.
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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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Yanagisawa K, Yasuda S, Kai M, Imai SI, Yamada K, Yamashita T, Jimbow K, Kanoh H, Sakane F. Diacylglycerol kinase α suppresses tumor necrosis factor-α-induced apoptosis of human melanoma cells through NF-κB activation. Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1771:462-74. [PMID: 17276726 DOI: 10.1016/j.bbalip.2006.12.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Revised: 11/15/2006] [Accepted: 12/18/2006] [Indexed: 10/23/2022]
Abstract
We investigated the implication of diacylglycerol kinase (DGK) alpha (type I isoform) in melanoma cells because we found that this DGK isoform was expressed in several human melanoma cell lines but not in noncancerous melanocytes. Intriguingly, the overexpression of wild-type (WT) DGKalpha, but not of its kinase-dead (KD) mutant, markedly suppressed tumor necrosis factor (TNF)-alpha-induced apoptosis of AKI human melanoma cells. In the reverse experiment, siRNA-mediated knockdown of DGKalpha significantly enhanced the apoptosis. The overexpression of other type I isoforms (DGKbeta and DGKgamma) had, on the other hand, no detectable effects on the apoptosis. These results indicate that DGKalpha specifically suppresses the TNF-alpha-induced apoptosis through its catalytic action. We found that the overexpression of DGKalpha-WT, but not of DGKalpha-KD, further enhanced the TNF-alpha-stimulated transcriptional activity of an anti-apoptotic factor, NF-kappaB. Conversely, DGKalpha-knockdown considerably inhibited the NF-kappaB activity. Moreover, an NF-kappaB inhibitor blunted the anti-apoptotic effect of DGKalpha overexpression. Together, these results strongly suggest that DGKalpha is a novel positive regulator of NF-kappaB, which suppresses TNF-alpha-induced melanoma cell apoptosis.
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Affiliation(s)
- Kenji Yanagisawa
- Department of Dermatology, Sapporo Medical University School of Medicine, Sapporo, Japan
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Borges K, Shaw R, Dingledine R. Gene expression changes after seizure preconditioning in the three major hippocampal cell layers. Neurobiol Dis 2007; 26:66-77. [PMID: 17239605 PMCID: PMC2295285 DOI: 10.1016/j.nbd.2006.12.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Revised: 10/31/2006] [Accepted: 12/05/2006] [Indexed: 12/23/2022] Open
Abstract
Rodents experience hippocampal damage after status epilepticus (SE) mainly in pyramidal cells while sparing the dentate granule cell layer (DGCL). Hippocampal damage was prevented in rats that had been preconditioned by brief seizures on 2 consecutive days before SE. To identify neuroprotective genes and biochemical pathways changed after preconditioning we compared the effect of preconditioning on gene expression in the CA1 and CA3 pyramidal and DGCLs, harvested by laser capture microscopy. In the DGCL the expression of 632 genes was altered, compared to only 151 and 58 genes in CA1 and CA3 pyramidal cell layers. Most of the differentially expressed genes regulate tissue structure and intra- and extracellular signaling, including neurotransmission. A selective upregulation of energy metabolism transcripts occurred in CA1 pyramidal cells relative to the DGCL. These results reveal a broad transcriptional response of the DGCL to preconditioning, and suggest several mechanisms underlying the neuroprotective effect of preconditioning seizures.
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Affiliation(s)
- Karin Borges
- Department of Pharmacology, School of Medicine, 1510 Clifton Rd, Emory University, Atlanta, GA 30322, USA.
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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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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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Nakano T, Hozumi Y, Ali H, Saino-Saito S, Kamii H, Sato S, Kayama T, Watanabe M, Kondo H, Goto K. Diacylglycerol kinase ζ is involved in the process of cerebral infarction. Eur J Neurosci 2006; 23:1427-35. [PMID: 16553606 DOI: 10.1111/j.1460-9568.2006.04685.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Diacylglycerol kinase (DGK) is an enzyme that phosphorylates a second messenger diacylglycerol (DG) and is involved in a variety of pathophysiological cellular responses. We have previously reported that DGKzeta may be involved in the selective vulnerability of hippocampal CA1 neurons in transient forebrain ischemia. In this study we aimed to further elucidate functional implications of DGK isozymes in the cerebral cortex suffering from infarction using a focal ischemic model. In the early phase of 90 min of middle cerebral artery occlusion, DGKzeta-immunoreactivity is reduced rapidly in the nucleus of cortical neurons in the ischemic core, while DGKiota and other neuronal proteins such as MAP-2 and NeuN remain intact. This suggests that rapid disappearance of DGKzeta in ischemic neurons is a quite early event precedent to neuronal degeneration in response to ischemia. Furthermore, in the late inflammatory phase of infarction DGKzeta-immunoreactivity is detected in non-neuronal cells including factor VIII-positive endothelial cells and ED-1-positive phagocytic cells. The present study suggests that DGKzeta may play roles in various processes of ischemic brain damage including neuronal death and non-neuronal inflammatory response.
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Affiliation(s)
- Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-nishi 2-2-2, Yamagata 990-9585, Japan
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Adachi N, Oyasu M, Taniguchi T, Yamaguchi Y, Takenaka R, Shirai Y, Saito N. Immunocytochemical localization of a neuron-specific diacylglycerol kinase beta and gamma in the developing rat brain. ACTA ACUST UNITED AC 2006; 139:288-99. [PMID: 16019106 DOI: 10.1016/j.molbrainres.2005.06.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2005] [Revised: 05/31/2005] [Accepted: 06/01/2005] [Indexed: 11/17/2022]
Abstract
Diacylglycerol kinase (DGK) phosphorylates diacylglycerol (DG) to produce phosphatidic acid (PA) and is, therefore, a potential terminator of DG signaling. DG and PA are important intracellular second messengers. DG directly binds protein kinase C (PKC) then activates this multifunctional enzyme. Ca2+-dependent and brain-specific DGKs, alpha, beta, and gamma, are suggested to play pivotal roles in the central nervous system. To elucidate the DGK function in neuronal development, we studied the developmental changes of DGKalpha, beta, and gamma in the postnatal rat brain. By immunoblot analysis, DGKalpha and gamma subtypes were present at birth and then gradually increased, while DGKbeta was not present at birth or postnatal day 3, then increased rapidly from day 14 to reach maximum at day 28. Immunohistochemically, DGKbeta and gamma were distributed in different brain regions. In most brain regions, DGKgamma showed sustained expression throughout the postnatal developmental periods. Interestingly, a temporal expression of DGKgamma was observed in the medial geniculate nucleus during day 3 to 14, and a delay of DGKgamma expression was seen in Purkinje cells, which was coincident with dendritic growth of Purkinje cells. In the hippocampal pyramidal cell, both DGKbeta and gamma were abundant but subcellular localization was different. DGKgamma localized in the cytosol while DGKbeta localized along the membrane structure. These findings suggest that each DGK subtype has a spatio-temporally different function in the developmental neurons.
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Affiliation(s)
- Naoko Adachi
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
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Yahagi H, Takeda M, Asaumi Y, Okumura K, Takahashi R, Takahashi J, Ohta J, Tada H, Minatoya Y, Sakuma M, Watanabe J, Goto K, Shirato K, Kagaya Y. Differential regulation of diacylglycerol kinase isozymes in cardiac hypertrophy. Biochem Biophys Res Commun 2005; 332:101-8. [PMID: 15896305 DOI: 10.1016/j.bbrc.2005.04.094] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Accepted: 04/21/2005] [Indexed: 11/20/2022]
Abstract
To examine the involvement of diacylglycerol kinase (DGK) and phosphatidic acid phosphatase (PAP) in pressure overloaded cardiac hypertrophy, rats were subjected to either ascending aortic banding for 3, 7, and 28 days or sham operation. In comparison with sham-operated rats, the left ventricular (LV) weight of the aortic-banded rats increased progressively. At 28 days after surgery, the expression of DGKepsilon mRNA but not DGKzeta or PAP2b mRNA in the LV myocardium significantly decreased in the aortic-banded rats compared with the sham-operated rats. DGKzeta protein in the LV myocardium translocated from the particulate to the cytosolic compartment in the aortic-banded rats. Furthermore, the myocardial content of 1,2-diacylglycerol and PKCdelta protein expression in the particulate fraction of the LV myocardium significantly increased in aortic-banded rats compared with sham-operated rats. These results suggest that DGKepsilon and DGKzeta play distinct roles in the development of pressure overloaded cardiac hypertrophy and that the two isozymes are differentially regulated.
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Affiliation(s)
- Hirokazu Yahagi
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan
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Toya M, Hozumi Y, Ito T, Takeda M, Sakane F, Kanoh H, Saito H, Hiroi M, Kurachi H, Kondo H, Goto K. Gene expression, cellular localization, and enzymatic activity of diacylglycerol kinase isozymes in rat ovary and placenta. Cell Tissue Res 2005; 320:525-33. [PMID: 15856307 DOI: 10.1007/s00441-005-1089-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2004] [Accepted: 01/21/2005] [Indexed: 11/28/2022]
Abstract
Female reproductive organs show remarkable cyclic changes in morphology and function in response to a combination of hormones. Evidence has accumulated suggesting that phosphoinositide turnover and the consequent diacylglycerol (DG) protein kinase C (PKC) pathway are intimately involved in these mechanisms. The present study has been performed to investigate the gene expression, cellular localization, and enzymatic activity of the DG kinase (DGK) isozymes that control the DG-PKC pathway. Gene expression for DGKalpha, -epsilon, -zeta, and -iota was detected in the ovary and placenta. Intense expression signals for DGKzeta and -alpha were observed in the theca cells and moderate signals in the interstitium and corpora lutea of the ovary. On the other hand, signals for DGKepsilon were seen more intensely in granulosa cells. In the placenta, signals for DGKalpha and -iota were observed in the junctional zone, whereas those for DGKzeta were detected in the labyrinthine zone. At higher magnification, the signals for DGKalpha were mainly discerned in giant cytotrophoblasts, and those for DGKiota were found in small cytotrophoblasts of the junctional zone. DGKzeta signals were observed in all cellular components of the labyrinthine zone, including mesenchyme, trabecular trophoblasts, and cytotrophoblasts. DGKepsilon signals were detected in the junctional zone on day 13 and 15 of pregnancy and were diffusely distributed both in the labyrinthine and junctional zones at later stages. The present study reveals distinct patterns of mRNA localization for DGK isozymes in the rat ovary and placenta, suggesting that each isozyme plays a unique role in distinct cell types in these organs.
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Affiliation(s)
- Mayumi Toya
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-nishi 2-2-2, Yamagata, 990-9585, Japan
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Fukunaga-Takenaka R, Shirai Y, Yagi K, Adachi N, Sakai N, Merino E, Merida I, Saito N. Importance of chroman ring and tyrosine phosphorylation in the subtype-specific translocation and activation of diacylglycerol kinase α by d-α-tocopherol. Genes Cells 2005; 10:311-9. [PMID: 15773894 DOI: 10.1111/j.1365-2443.2005.00842.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Diacylglycerol kinase (DGK) has been suggested to be a pharmacological target of D-alpha-tocopherol for diabetic renal dysfunctions. However, the DGK subtypes involved in the D-alpha-tocopherol-induced improvement of diabetic renal dysfunctions and the activation mechanisms of DGK by D-alpha-tocopherol are still unknown. Therefore, using GFP-tagged DGKalpha, beta, gamma, epsilon and zeta, we analyzed their response to D-alpha-tocopherol and its derivatives. Only DGKalpha was translocated from the cytoplasm to the plasma membrane with elevation of kinase activity. In addition, troglitazone and trolox possessing 'chroman ring' similarly to D-alpha-tocopherol, induced the subtype-specific translocation of DGKalpha. Furthermore, the translocation of DGKalpha was abolished by pretreatment with tyrosine kinase inhibitors or by mutation on Tyr-334 of the kinase (YF mutant). D-alpha-tocopheryl succinate enhanced the Src-mediated tyrosine phosphorylation of wild-type DGKalpha but the same reagent did not enhance that of the YF mutant. These results demonstrate that tyrosine phosphorylation on Tyr-334 and chroman ring are important for the D-alpha-tocopherol-induced translocation of DGKalpha.
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Affiliation(s)
- Rika Fukunaga-Takenaka
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Nadaku, Kobe 657-8501, Japan
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Katagiri Y, Ito T, Saino-Saito S, Hozumi Y, Suwabe A, Otake K, Sata M, Kondo H, Sakane F, Kanoh H, Kubota I, Goto K. Expression and localization of diacylglycerol kinase isozymes and enzymatic features in rat lung. Am J Physiol Lung Cell Mol Physiol 2005; 288:L1171-8. [PMID: 15734788 DOI: 10.1152/ajplung.00237.2004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Diacylglycerol kinase (DGK) catalyzes phosphorylation of diacylglycerol to generate phosphatidic acid, and both molecules are known to serve as second messengers as well as important intermediates for the synthesis of various lipids. In this study, we investigated the spatiotemporal expression patterns of DGK isozymes together with the developmental changes of the mRNA expression and enzymatic property in rat lung. Northern blot and RT-PCR analyses showed that mRNAs for DGKalpha, -epsilon, and -zeta were detected in the lung. By immunohistochemical examination, DGKalpha and -zeta were shown to be coexpressed in alveolar type II cells and macrophages. Interestingly, these isozymes were localized at distinct subcellular locations, i.e., DGKalpha in the cytoplasm and DGKzeta in the nucleus, suggesting different roles for these isozymes. In the developing lung, the expression for DGKalpha and -zeta was transiently elevated on embryonic day 21 (E21) to levels approximately two- to threefold higher than on postnatal day 0 (P0). On the other hand, the expression for DGKepsilon was inversely elevated approximately twofold on P0 compared with that on E21. These unique changes in the expression pattern during the perinatal period suggest that each isozyme may play a distinct role in the adaptation of the lung to air or oxygen breathing at birth.
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Affiliation(s)
- Yuji Katagiri
- Dept. of Anatomy and Cell Biology, Yamagata Univ. School of Medicine, Iida-Nishi 2-2-2, Yamagata 990-9585, Japan
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47
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Ali H, Nakano T, Saino-Saito S, Hozumi Y, Katagiri Y, Kamii H, Sato S, Kayama T, Kondo H, Goto K. Selective translocation of diacylglycerol kinase ζ in hippocampal neurons under transient forebrain ischemia. Neurosci Lett 2004; 372:190-5. [PMID: 15542238 DOI: 10.1016/j.neulet.2004.09.052] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Revised: 09/10/2004] [Accepted: 09/11/2004] [Indexed: 10/26/2022]
Abstract
The molecular mechanisms responsible for differential neuronal vulnerability to ischemic injury are incompletely understood. Previous studies have reported that the expression and activity of protein kinase C (PKC), some subtypes of which are activated by Ca(2+) and diacylglycerol (DG), are altered after ischemic insults. Therefore, DG kinase (DGK), which is responsible for controlling PKC activity through DG metabolism, may also be involved in this process. DGKzeta, which is abundantly expressed in the brain, contains a nuclear localization signal (NLS), suggesting its involvement in some nuclear processes in neuronal cells. To elucidate the functional implications of DGKzeta in ischemia, we examined detailed localization of DGKzeta in rat brain after ischemic insults. We used an ischemic model of global cerebral ischemia for 20 min by bilateral common carotid artery occlusion combined with hypotension and followed time-points of reperfusion. DGKzeta expression was evaluated by immunohistochemistry using affinity-purified anti-DGKzeta antibody. In sham-operated rats, a strong DGKzeta-immunoreactivity was observed in the nucleus of neurons in various parts of the brain. In the global ischemic model DGKzeta-immunoreactivity was reduced in intensity in the hippocampal formation and detected in the cytoplasm of CA1 pyramidal neurons throughout reperfusion time courses. Change in the subcellular localization was restricted to the pyramidal cells in CA1 and later in CA3, but not observed in other areas of hippocampus. No change was observed in the cerebral and cerebellar cortices. The present study suggests that DGKzeta might be involved in the process of selective vulnerability of hippocampal pyramidal neurons in postischemic brain.
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Affiliation(s)
- Hasmat Ali
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-nishi 2-2-2, Yamagata 990-9585, Japan
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Tsushima S, Kai M, Yamada K, Imai SI, Houkin K, Kanoh H, Sakane F. Diacylglycerol Kinase γ Serves as an Upstream Suppressor of Rac1 and Lamellipodium Formation. J Biol Chem 2004; 279:28603-13. [PMID: 15102830 DOI: 10.1074/jbc.m314031200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Nine diacylglycerol kinase (DGK) isozymes have been identified. However, our knowledge of their individual functions is still limited. Here, we demonstrate the role of DGKgamma in regulating Rac1-governed cell morphology. We found that the expression of kinase-dead DGKgamma, which acts as a dominant-negative mutant, and inhibition of endogenous DGKgamma activity with R59949 induced lamellipodium and membrane ruffle formation in NIH3T3 fibroblasts in the absence of growth factor stimulation. Reciprocally, lamellipodium formation induced by platelet-derived growth factor was significantly inhibited upon expression of constitutively active DGKgamma. Moreover, the constitutively active DGKgamma mutant suppressed integrin-mediated cell spreading. These effects are isoform-specific because, in the same experiments, none of the corresponding mutants of DGKalpha and DGKbeta, closely related isoforms, affected cell morphology. These results suggest that DGKgamma specifically participates in the Rac1-mediated signaling pathway leading to cytoskeletal reorganization. In support of this, DGKgamma co-localized with dominant-active Rac1 especially in lamellipodia. Moreover, we found that endogenous DGKgamma was physically associated with cellular Rac1. Dominant-negative Rac1 expression blocked the lamellipodium formation induced by kinase-dead DGKgamma, indicating that DGKgamma acts upstream of Rac1. This model is supported by studies demonstrating that kinase-dead DGKgamma selectively activated Rac1, but not Cdc42. Taken together, these results strongly suggest that DGKgamma functions through its catalytic action as an upstream suppressor of Rac1 and, consequently, lamellipodium/ruffle formation.
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Affiliation(s)
- Shuichi Tsushima
- Department of Biochemistry, Sapporo Medical University School of Medicine, South-1 West-17, Chuo-ku, Sapporo 060-8556, Japan
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49
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Ito T, Hozumi Y, Sakane F, Saino-Saito S, Kanoh H, Aoyagi M, Kondo H, Goto K. Cloning and Characterization of Diacylglycerol Kinase ι Splice Variants in Rat Brain. J Biol Chem 2004; 279:23317-26. [PMID: 15024004 DOI: 10.1074/jbc.m312976200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Diacylglycerol kinase (DGK) catalyzes phosphorylation of a second messenger diacylglycerol (DG) to phosphatidic acid in cellular signal transduction. Previous studies have revealed that DGK consists of a family of isozymes including our rat clones. In this study we isolated from rat brain cDNA library the cDNA clones for a rat homologue of DGKiota (rDGKiota-1) that contains two zinc finger-like sequences, the highly conserved DGK catalytic domain, a bipartite nuclear localization signal, and four ankyrin repeats at the carboxyl terminus. In addition, we found novel splice variants, which contain either insertion 1 (71 bp) or insertion 2 (19 bp) or both in the carboxyl-terminal portion. Each of the insertions causes a frameshift, and the resultant premature stop codons produce two truncated forms (termed rDGKiota-2 and -iota-3), the former lacking the ankyrin repeats at the carboxyl terminus and the latter lacking a part of the catalytic domain and the ankyrin repeats. Truncation of the carboxyl-terminal portion clearly exerts effects on the detergent solubility and enzymatic activity of the splice variants, although all three variants showed similar cytoplasmic localization in cDNA-transfected cultured neurons despite the continued presence of the nuclear localization signal sequence. Immunoblot analysis using anti-rDGKiota antibody raised against the common amino-terminal portion clearly shows that these rDGKiota variants are indeed expressed in the brain. These results suggest that the carboxyl-terminal truncated forms of rDGKiota-2 and -iota-3 that exhibit reduced enzymatic activities might show a dominant negative effect against the intact rDGKiota-1, and that the modulation of signal transduction by the splice variants may play some roles in the physiologic and/or pathologic conditions of neurons.
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Affiliation(s)
- Tsukasa Ito
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Japan
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50
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Affiliation(s)
- Koaru Goto
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-Nishi 2-2-2, Yamagata 990-9585, Japan.
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