1
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Barbernitz MX, Devine LR, Cole RN, Raben DM. The role of N-terminal phosphorylation of DGK-θ. J Lipid Res 2024; 65:100506. [PMID: 38272356 PMCID: PMC10914586 DOI: 10.1016/j.jlr.2024.100506] [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: 12/06/2023] [Revised: 01/13/2024] [Accepted: 01/16/2024] [Indexed: 01/27/2024] Open
Abstract
Diacylglycerol kinases (DGKs) are lipid kinases that mediate the phosphorylation of diacylglycerol (DAG) leading to the production of phosphatidic acid (PtdOH). To examine the role of phosphorylation on DGK-θ, we first identified the phosphorylated sites on endogenous DGK-θ from mouse brain and found four sites: S15, S17, which we refer to phosphomotif-1 sites, and S22 and S26 which we refer to as phosphomotif-2 sites. This study focused on the role of these phosphorylated sites on enzyme activity, membrane binding, thermal stability, and cellular half-life of DGK-θ. After generating a construct devoid of all non-catalytic phosphorylation sites (4A), we also generated other constructs to mimic phosphorylation of these residues by mutating them to glutamate (E). Our data demonstrate that an increase in membrane affinity requires the phosphorylation of all four endogenous sites as the phosphomimetic 4E but not other phosphomimietics. Furthermore, 4E also shows an increase in basal activity as well as an increase in the Syt1-induced activity compared to 4A. It is noteworthy that these phosphorylations had no effect on the thermal stability or cellular half-life of this enzyme. Interestingly, when only one phosphorylation domain (phosphomotif-1 or phosphomotif-2) contained phosphomimetics (S15E/S17E or S22E/S26E), the basal activity was also increased but membrane binding affinity was not increased. Furthermore, when only one residue in each domain mimicked an endogenous phosphorylated serine (S15E/S22E or S17E/S26E), the Syt1-induced activity as well as membrane binding affinity decreased relative to 4A. These results indicate that these endogenous phosphorylation sites contribute differentially to membrane binding and enzymatic activity.
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Affiliation(s)
- Millie X Barbernitz
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Lauren R Devine
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Robert N Cole
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Daniel M Raben
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Physiology and Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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2
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Xiao Q, Wang D, Li D, Huang J, Ma F, Zhang H, Sheng Y, Zhang C, Ha X. Protein kinase C: A potential therapeutic target for endothelial dysfunction in diabetes. J Diabetes Complications 2023; 37:108565. [PMID: 37540984 DOI: 10.1016/j.jdiacomp.2023.108565] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 07/13/2023] [Accepted: 07/22/2023] [Indexed: 08/06/2023]
Abstract
Protein kinase C (PKC) is a family of serine/threonine protein kinases that play an important role in many organs and systems and whose activation contributes significantly to endothelial dysfunction in diabetes. The increase in diacylglycerol (DAG) under high glucose conditions mediates PKC activation and synthesis, which stimulates oxidative stress and inflammation, resulting in impaired endothelial cell function. This article reviews the contribution of PKC to the development of diabetes-related endothelial dysfunction and summarizes the drugs that inhibit PKC activation, with the aim of exploring therapeutic modalities that may alleviate endothelial dysfunction in diabetic patients.
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Affiliation(s)
- Qian Xiao
- Department of Laboratory, Ninth Forty Hospital of the Chinese People's Liberation Army Joint Security Force, Lanzhou 730050, Gansu, China; School of Public Health, Gansu University of Traditional Chinese Medicine, Lanzhou 730000, Gansu, China
| | - Dan Wang
- Department of Laboratory, Ninth Forty Hospital of the Chinese People's Liberation Army Joint Security Force, Lanzhou 730050, Gansu, China; School of Public Health, Gansu University of Traditional Chinese Medicine, Lanzhou 730000, Gansu, China
| | - Danyang Li
- School of Public Health, Gansu University of Traditional Chinese Medicine, Lanzhou 730000, Gansu, China
| | - Jing Huang
- Department of Laboratory, Ninth Forty Hospital of the Chinese People's Liberation Army Joint Security Force, Lanzhou 730050, Gansu, China; School of Public Health, Gansu University of Traditional Chinese Medicine, Lanzhou 730000, Gansu, China
| | - Feifei Ma
- Department of Laboratory, Ninth Forty Hospital of the Chinese People's Liberation Army Joint Security Force, Lanzhou 730050, Gansu, China; College of Veterinary Medicine, Gansu Agriculture University, Lanzhou 730070, Gansu, China
| | - Haocheng Zhang
- Department of Laboratory, Ninth Forty Hospital of the Chinese People's Liberation Army Joint Security Force, Lanzhou 730050, Gansu, China; The Second School of Clinical Medicine, Lanzhou University, Lanzhou, 730030, Gansu, China
| | - Yingda Sheng
- Department of Laboratory, Ninth Forty Hospital of the Chinese People's Liberation Army Joint Security Force, Lanzhou 730050, Gansu, China; School of Public Health, Gansu University of Traditional Chinese Medicine, Lanzhou 730000, Gansu, China
| | - Caimei Zhang
- Department of Laboratory, Ninth Forty Hospital of the Chinese People's Liberation Army Joint Security Force, Lanzhou 730050, Gansu, China; School of Public Health, Gansu University of Traditional Chinese Medicine, Lanzhou 730000, Gansu, China
| | - Xiaoqin Ha
- Department of Laboratory, Ninth Forty Hospital of the Chinese People's Liberation Army Joint Security Force, Lanzhou 730050, Gansu, China; School of Public Health, Gansu University of Traditional Chinese Medicine, Lanzhou 730000, Gansu, China.
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3
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Barbernitz X, Raben DM. Phosphorylation of DGK. Adv Biol Regul 2022; 88:100941. [PMID: 36508895 DOI: 10.1016/j.jbior.2022.100941] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/02/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022]
Abstract
Diacylglycerol (DAG) and phosphatidic acid (PtdOH) play important roles in a variety of signaling cascades (Carrasco and Merida, 2007; Stace and Ktistakis, 2006). Therefore, the physiological roles and regulatory mechanisms controlling the levels of these lipids are important. One class of enzymes capable of coordinating the levels of these two lipids are the diacylglycerol kinases (DGKs). DGKs catalyze the transfer of the γ-phosphate of ATP to the hydroxyl group of DAG which generates PtdOH(Merida et al., 2008; Sakane et al., 2007). As DGKs reciprocally modulate the relative levels of these two signaling lipids, it is not surprising that there is increasing interest in understanding the mechanism underlying the catalysis and regulation of these kinases. While post-translational modifications (PTMs) are often involved in enzyme regulation, there is surprisingly little information regarding the PTMs on these enzymes and their roles in modulating their activity and function. In this review, we will summarize what is known about one PTM on DGKs, phosphorylation, and the possible functions of this modification.
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Affiliation(s)
- Xin Barbernitz
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Daniel M Raben
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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4
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Hayashi D, Mouchlis VD, Okamoto S, Namba T, Wang L, Li S, Ueda S, Yamanoue M, Tachibana H, Arai H, Ashida H, Dennis EA, Shirai Y. Vitamin E functions by association with a novel binding site on the 67 kDa laminin receptor activating diacylglycerol kinase. J Nutr Biochem 2022; 110:109129. [PMID: 35977663 PMCID: PMC10243646 DOI: 10.1016/j.jnutbio.2022.109129] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 03/27/2022] [Accepted: 07/16/2022] [Indexed: 01/13/2023]
Abstract
It is generally recognized that the main function of α-tocopherol (αToc), which is the most active form of vitamin E, is its antioxidant effect, while non-antioxidant effects have also been reported. We previously found that αToc ameliorates diabetic nephropathy via diacylglycerol kinase alpha (DGKα) activation in vivo, and the activation was not related to the antioxidant effect. However, the underlying mechanism of how αToc activates DGKα have been enigmatic. We report that the membrane-bound 67 kDa laminin receptor (67LR), which has previously been shown to serve as a receptor for epigallocatechin gallate (EGCG), also contains a novel binding site for vitamin E, and its association with Vitamin E mediates DGKα activation by αToc. We employed hydrogen-deuterium exchange mass spectrometry (HDX/MS) and molecular dynamics (MD) simulations to identify the specific binding site of αToc on the 67LR and discovered the conformation of the specific hydrophobic pocket that accommodates αToc. Also, HDX/MS and MD simulations demonstrated the detailed binding of EGCG to a water-exposed hydrophilic site on 67LR, while in contrast αToc binds to a distinct hydrophobic site. We demonstrated that 67LR triggers an important signaling pathway mediating non-antioxidant effects of αToc, such as DGKα activation. This is the first evidence demonstrating a membrane receptor for αToc and one of the underlying mechanisms of a non-antioxidant function for αToc.
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Affiliation(s)
- Daiki Hayashi
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Kobe, Japan; Department of Pharmacology, and Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, USA
| | - Varnavas D Mouchlis
- Department of Pharmacology, and Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, USA
| | - Seika Okamoto
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Kobe, Japan
| | - Tomoka Namba
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Kobe, Japan
| | - Liuqing Wang
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Kobe, Japan
| | - Sheng Li
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Shuji Ueda
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Kobe, Japan
| | - Minoru Yamanoue
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Kobe, Japan
| | - Hirofumi Tachibana
- Division of Applied Biological Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Hiroyuki Arai
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo Japan
| | - Hitoshi Ashida
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Kobe, Japan
| | - Edward A Dennis
- Department of Pharmacology, and Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, USA
| | - Yasuhito Shirai
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Kobe, Japan.
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5
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Morita SY, Ikeda Y. Regulation of membrane phospholipid biosynthesis in mammalian cells. Biochem Pharmacol 2022; 206:115296. [DOI: 10.1016/j.bcp.2022.115296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 10/05/2022] [Accepted: 10/05/2022] [Indexed: 11/02/2022]
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The Role of Diacylglycerol Kinase in the Amelioration of Diabetic Nephropathy. Molecules 2022; 27:molecules27206784. [PMID: 36296376 PMCID: PMC9607625 DOI: 10.3390/molecules27206784] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 10/05/2022] [Accepted: 10/07/2022] [Indexed: 12/02/2022] Open
Abstract
The drastic increase in the number of patients with diabetes and its complications is a global issue. Diabetic nephropathy, the leading cause of chronic kidney disease, significantly affects patients’ quality of life and medical expenses. Furthermore, there are limited drugs for treating diabetic nephropathy patients. Impaired lipid signaling, especially abnormal protein kinase C (PKC) activation by de novo-synthesized diacylglycerol (DG) under high blood glucose, is one of the causes of diabetic nephropathy. DG kinase (DGK) is an enzyme that phosphorylates DG and generates phosphatidic acid, i.e., DGK can inhibit PKC activation under diabetic conditions. Indeed, it has been proven that DGK activation ameliorates diabetic nephropathy. In this review, we summarize the involvement of PKC and DGK in diabetic nephropathy as therapeutic targets, and its mechanisms, by referring to our recent study.
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7
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Sakane F, Hoshino F, Ebina M, Sakai H, Takahashi D. The Roles of Diacylglycerol Kinase α in Cancer Cell Proliferation and Apoptosis. Cancers (Basel) 2021; 13:cancers13205190. [PMID: 34680338 PMCID: PMC8534027 DOI: 10.3390/cancers13205190] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 10/14/2021] [Accepted: 10/14/2021] [Indexed: 02/02/2023] Open
Abstract
Simple Summary Diacylglycerol (DG) kinase (DGK) phosphorylates DG to generate phosphatidic acid (PA). DGKα is highly expressed in several refractory cancer cells, including melanoma, hepatocellular carcinoma, and glioblastoma cells, attenuates apoptosis, and promotes proliferation. In cancer cells, PA produced by DGKα plays an important role in proliferation/antiapoptosis. In addition to cancer cells, DGKα is highly abundant in T cells and induces a nonresponsive state (anergy), representing the main mechanism by which advanced cancers avoid immune action. In T cells, DGKα induces anergy through DG consumption. Therefore, a DGKα-specific inhibitor is expected to be a dual effective anticancer treatment that inhibits cancer cell proliferation and simultaneously activates T cell function. Moreover, the inhibition of DGKα synergistically enhances the anticancer effects of programmed cell death-1/programmed cell death ligand 1 blockade. Taken together, DGKα inhibition provides a promising new treatment strategy for refractory cancers. Abstract Diacylglycerol (DG) kinase (DGK) phosphorylates DG to generate phosphatidic acid (PA). The α isozyme is activated by Ca2+ through its EF-hand motifs and tyrosine phosphorylation. DGKα is highly expressed in several refractory cancer cells including melanoma, hepatocellular carcinoma, and glioblastoma cells. In melanoma cells, DGKα is an antiapoptotic factor that activates nuclear factor-κB (NF-κB) through the atypical protein kinase C (PKC) ζ-mediated phosphorylation of NF-κB. DGKα acts as an enhancer of proliferative activity through the Raf–MEK–ERK pathway and consequently exacerbates hepatocellular carcinoma progression. In glioblastoma and melanoma cells, DGKα attenuates apoptosis by enhancing the phosphodiesterase (PDE)-4A1–mammalian target of the rapamycin pathway. As PA activates PKCζ, Raf, and PDE, it is likely that PA generated by DGKα plays an important role in the proliferation/antiapoptosis of cancer cells. In addition to cancer cells, DGKα is highly abundant in T cells and induces a nonresponsive state (anergy), which represents the main mechanism by which advanced cancers escape immune action. In T cells, DGKα attenuates the activity of Ras-guanyl nucleotide-releasing protein, which is activated by DG and avoids anergy through DG consumption. Therefore, a DGKα-specific inhibitor is expected to be a dual effective anticancer treatment that inhibits cancer cell proliferation and simultaneously enhances T cell functions. Moreover, the inhibition of DGKα synergistically enhances the anticancer effects of programmed cell death-1/programmed cell death ligand 1 blockade. Taken together, DGKα inhibition provides a promising new treatment strategy for refractory cancers.
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Affiliation(s)
- Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan; (F.H.); (M.E.)
- Correspondence: ; Tel.: +81-43-290-3695
| | - Fumi Hoshino
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan; (F.H.); (M.E.)
| | - Masayuki Ebina
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan; (F.H.); (M.E.)
| | - Hiromichi Sakai
- Department of Biosignaling and Radioisotope Experiment, Interdisciplinary Center for Science Research, Organization for Research and Academic Information, Shimane University, Izumo 693-8501, Japan;
| | - Daisuke Takahashi
- Department of Pharmaceutical Health Care and Sciences, Kyushu University, Fukuoka 812-8582, Japan;
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8
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Lee H. Vitamin E acetate as linactant in the pathophysiology of EVALI. Med Hypotheses 2020; 144:110182. [PMID: 33254504 PMCID: PMC7422838 DOI: 10.1016/j.mehy.2020.110182] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/25/2020] [Accepted: 08/11/2020] [Indexed: 11/11/2022]
Abstract
The recent identification of Vitamin E acetate as one of the causal agents for the e-cigarette, or vaping, product use associated lung injury (EVALI) is a major milestone. In membrane biophysics, Vitamin E is a linactant and a potent modulator of lateral phase separation that effectively reduces the line tension at the two-dimensional phase boundaries and thereby exponentially increases the surface viscosity of the pulmonary surfactant. Disrupted dynamics of respiratory compression-expansion cycling may result in an extensive hypoxemia, leading to an acute respiratory distress entailing the formation of intraalveolar lipid-laden macrophages. Supplementation of pulmonary surfactants which retain moderate level of cholesterol and controlled hypothermia for patients are recommended when the hypothesis that the line-active property of the vitamin derivative drives the pathogenesis of EVALI holds.
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Affiliation(s)
- Hanjun Lee
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, United States.
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9
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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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10
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Hayashi D, Wang L, Ueda S, Yamanoue M, Ashida H, Shirai Y. The mechanisms of ameliorating effect of a green tea polyphenol on diabetic nephropathy based on diacylglycerol kinase α. Sci Rep 2020; 10:11790. [PMID: 32678222 PMCID: PMC7366667 DOI: 10.1038/s41598-020-68716-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 06/16/2020] [Indexed: 12/19/2022] Open
Abstract
Significant efforts have been made to ameliorate diabetic nephropathy (DN) by inhibiting protein kinase C. However, these efforts have not been successful in human trials, suggesting that novel therapeutic strategies are required. Thus far, it has been reported that green tea polyphenol epigallocatechin gallate (EGCg) improved albuminuria in DN in a human trial. Our previous study revealed that activation of diacylglycerol kinase α (DGKα) plays a crucial role in the amelioration of DN and that EGCg activates DGKα. Here, we investigated whether and how DGKα contributes to the amelioration of DN upon stimulation by EGCg by using streptozotocin-induced type 1 diabetic model mice. Our results revealed that EGCg ameliorated albuminuria in DN through DGKα in vivo, and methylated EGCg, which has higher absorption in the plasma improved albuminuria in DN effectively. Additionally, we showed that c-Src mediated EGCg-induced DGKα translocation and colocalized with the 67 kDa laminin receptor, which is an EGCg receptor. Furthermore, EGCg attenuated the loss of podocytes in DN by preventing a decrease in focal adhesion under high glucose conditions. Our results indicate that the DGKα pathway is an attractive therapeutic target and that activating this pathway is a novel strategy for treating DN.
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Affiliation(s)
- Daiki Hayashi
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Rokkodai-Cho 1-1, Nada-Ku, Kobe, 657-8501, Japan
| | - Liuqing Wang
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Rokkodai-Cho 1-1, Nada-Ku, Kobe, 657-8501, Japan
| | - Shuji Ueda
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Rokkodai-Cho 1-1, Nada-Ku, Kobe, 657-8501, Japan
| | - Minoru Yamanoue
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Rokkodai-Cho 1-1, Nada-Ku, Kobe, 657-8501, Japan
| | - Hitoshi Ashida
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Rokkodai-Cho 1-1, Nada-Ku, Kobe, 657-8501, Japan
| | - Yasuhito Shirai
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Rokkodai-Cho 1-1, Nada-Ku, Kobe, 657-8501, Japan.
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11
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Di Vincenzo A, Tana C, El Hadi H, Pagano C, Vettor R, Rossato M. Antioxidant, Anti-Inflammatory, and Metabolic Properties of Tocopherols and Tocotrienols: Clinical Implications for Vitamin E Supplementation in Diabetic Kidney Disease. Int J Mol Sci 2019; 20:ijms20205101. [PMID: 31618817 PMCID: PMC6834186 DOI: 10.3390/ijms20205101] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 10/09/2019] [Accepted: 10/14/2019] [Indexed: 12/23/2022] Open
Abstract
Diabetes mellitus is a metabolic disorder characterized by the development of vascular complications associated with high morbidity and mortality and the consequent relevant costs for the public health systems. Diabetic kidney disease is one of these complications that represent the main cause of end-stage renal disease in Western countries. Hyperglycemia, inflammation, and oxidative stress contribute to its physiopathology, and several investigations have been performed to evaluate the role of antioxidant supplementation as a complementary approach for the prevention and control of diabetes and associated disturbances. Vitamin E compounds, including different types of tocopherols and tocotrienols, have been considered as a treatment to tackle major cardiovascular outcomes in diabetic subjects, but often with conflicting or even negative results. However, their effects on diabetic nephropathy are even less clear, despite several intervention studies that showed the improvement of renal parameters after supplementation in patients with diabetic kidney disease. Then we performed a review of the literature about the role of vitamin E supplementation on diabetic nephropathy, also describing the underlying antioxidant, anti-inflammatory, and metabolic mechanisms to evaluate the possible use of tocopherols and tocotrienols in clinical practice.
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Affiliation(s)
- Angelo Di Vincenzo
- Department of Medicine-DIMED, Clinica Medica 3, Center for the Study and Integrated Management of Obesity, University-Hospital of Padova, 35100 Padova, Italy.
| | - Claudio Tana
- Internal Medicine and Critical Subacute Care Unit, Medicine Geriatric-Rehabilitation Department, and Department of Medicine and Surgery, University-Hospital of Parma, 43126 Parma, Italy.
| | - Hamza El Hadi
- Department of Medicine-DIMED, Clinica Medica 3, Center for the Study and Integrated Management of Obesity, University-Hospital of Padova, 35100 Padova, Italy.
- Department of Medicine, Klinikum Rheine, 48431 Rheine, Germany.
| | - Claudio Pagano
- Department of Medicine-DIMED, Clinica Medica 3, Center for the Study and Integrated Management of Obesity, University-Hospital of Padova, 35100 Padova, Italy.
| | - Roberto Vettor
- Department of Medicine-DIMED, Clinica Medica 3, Center for the Study and Integrated Management of Obesity, University-Hospital of Padova, 35100 Padova, Italy.
| | - Marco Rossato
- Department of Medicine-DIMED, Clinica Medica 3, Center for the Study and Integrated Management of Obesity, University-Hospital of Padova, 35100 Padova, Italy.
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12
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Hayashi D, Tsumagari R, Liu K, Ueda S, Yamanoue M, Sakane F, Shirai Y. Screening of subtype-specific activators and inhibitors for diacylglycerol kinase. J Biochem 2019; 165:517-522. [DOI: 10.1093/jb/mvz008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 02/03/2019] [Indexed: 12/17/2022] Open
Affiliation(s)
- Daiki Hayashi
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Rokkodai-cho 1-1, Nada-ku, Kobe, Japan
| | - Ryosuke Tsumagari
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Rokkodai-cho 1-1, Nada-ku, Kobe, Japan
| | - Ke Liu
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, Japan
| | - Shuji Ueda
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Rokkodai-cho 1-1, Nada-ku, Kobe, Japan
| | - Minoru Yamanoue
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Rokkodai-cho 1-1, Nada-ku, Kobe, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, Japan
| | - Yasuhito Shirai
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Rokkodai-cho 1-1, Nada-ku, Kobe, Japan
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13
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Merida I, Arranz-Nicolás J, Torres-Ayuso P, Ávila-Flores A. Diacylglycerol Kinase Malfunction in Human Disease and the Search for Specific Inhibitors. Handb Exp Pharmacol 2019; 259:133-162. [PMID: 31227890 DOI: 10.1007/164_2019_221] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The diacylglycerol kinases (DGKs) are master regulator kinases that control the switch from diacylglycerol (DAG) to phosphatidic acid (PA), two lipids with important structural and signaling properties. Mammalian DGKs distribute into five subfamilies that regulate local availability of DAG and PA pools in a tissue- and subcellular-restricted manner. Pharmacological manipulation of DGK activity holds great promise, given the critical contribution of specific DGK subtypes to the control of membrane structure, signaling complexes, and cell-cell communication. The latest advances in the DGK field have unveiled the differential contribution of selected isoforms to human disease. Defects in the expression/activity of individual DGK isoforms contribute substantially to cognitive impairment, mental disorders, insulin resistance, and vascular pathologies. Abnormal DGK overexpression, on the other hand, confers the acquisition of malignant traits including invasion, chemotherapy resistance, and inhibition of immune attack on tumors. Translation of these findings into therapeutic approaches will require development of methods to pharmacologically modulate DGK functions. In particular, inhibitors that target the DGKα isoform hold particular promise in the fight against cancer, on their own or in combination with immune-targeting therapies.
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Affiliation(s)
- Isabel Merida
- Department of Immunology and Oncology, National Center of Biotechnology (CNB-CSIC), Madrid, Spain.
| | - Javier Arranz-Nicolás
- Department of Immunology and Oncology, National Center of Biotechnology (CNB-CSIC), Madrid, Spain
| | - Pedro Torres-Ayuso
- Laboratory of Cell and Developmental Signaling, National Cancer Institute (NCI-NIH), Frederick, MD, USA
| | - Antonia Ávila-Flores
- Department of Immunology and Oncology, National Center of Biotechnology (CNB-CSIC), Madrid, Spain
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14
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Trinh I, Gluscencova OB, Boulianne GL. An in vivo screen for neuronal genes involved in obesity identifies Diacylglycerol kinase as a regulator of insulin secretion. Mol Metab 2018; 19:13-23. [PMID: 30389349 PMCID: PMC6323187 DOI: 10.1016/j.molmet.2018.10.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 09/26/2018] [Accepted: 10/15/2018] [Indexed: 12/31/2022] Open
Abstract
Objective Obesity is a complex disorder involving many genetic and environmental factors that are required to maintain energy homeostasis. While studies in human populations have led to significant progress in the generation of an obesity gene map and broadened our understanding of the genetic basis of common obesity, there is still a large portion of heritability and etiology that remains unknown. Here, we have used the genetically tractable fruit fly, Drosophila melanogaster, to identify genes/pathways that function in the nervous system to regulate energy balance. Methods We performed an in vivo RNAi screen in Drosophila neurons and assayed for obese or lean phenotypes by measuring changes in levels of stored fats (in the form of triacylglycerides or TAG). Three rounds of screening were performed to verify the reproducibility and specificity of the adiposity phenotypes. Genes that produced >25% increase in TAG (206 in total) underwent a second round of screening to verify their effect on TAG levels by retesting the same RNAi line to validate the phenotype. All remaining hits were screened a third time by testing the TAG levels of additional RNAi lines against the genes of interest to rule out any off-target effects. Results We identified 24 genes including 20 genes that have not been previously associated with energy homeostasis. One identified hit, Diacylglycerol kinase (Dgk), has mammalian homologues that have been implicated in genome-wide association studies for metabolic defects. Downregulation of neuronal Dgk levels increases TAG and carbohydrate levels and these phenotypes can be recapitulated by reducing Dgk levels specifically within the insulin-producing cells that secrete Drosophila insulin-like peptides (dILPs). Conversely, overexpression of kinase-dead Dgk, but not wild-type, decreased circulating dILP2 and dILP5 levels resulting in lower insulin signalling activity. Despite having higher circulating dILP levels, Dgk RNAi flies have decreased pathway activity suggesting that they are insulin-resistant. Conclusion Altogether, we have identified several genes that act within the CNS to regulate energy homeostasis. One of these, Dgk, acts within the insulin-producing cells to regulate the secretion of dILPs and energy homeostasis in Drosophila. RNAi screen in neurons identifies 24 regulators of energy homeostasis. One of the hits, Dgk, affects lipid and carbohydrate homeostasis. Dgk acts within the IPCs to regulate dILP secretion and insulin signalling activity.
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Affiliation(s)
- Irene Trinh
- Department of Molecular Genetics, University of Toronto, Toronto, M5S 1A8, Canada; Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Peter Gilgan Center for Research and Learning, 686 Bay Street, Toronto, M5G 0A6, Canada.
| | - Oxana B Gluscencova
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Peter Gilgan Center for Research and Learning, 686 Bay Street, Toronto, M5G 0A6, Canada.
| | - Gabrielle L Boulianne
- Department of Molecular Genetics, University of Toronto, Toronto, M5S 1A8, Canada; Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Peter Gilgan Center for Research and Learning, 686 Bay Street, Toronto, M5G 0A6, Canada.
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15
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Liu P, Wang PS. Palladium-catalyzed Asymmetric Allylic C–H Oxidation for the Formal Synthesis of Gonytolide C. CHEM LETT 2017. [DOI: 10.1246/cl.170406] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Peng Liu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, P. R. China
| | - Pu-Sheng Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, P. R. China
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16
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Diacylglycerol Kinase alpha is Involved in the Vitamin E-Induced Amelioration of Diabetic Nephropathy in Mice. Sci Rep 2017; 7:2597. [PMID: 28572624 PMCID: PMC5453949 DOI: 10.1038/s41598-017-02354-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 04/10/2017] [Indexed: 02/05/2023] Open
Abstract
Diabetic nephropathy (DN) is one of vascular complications of diabetes and is caused by abnormal protein kinase C activation as a result of increased diacylglycerol (DG) production in diabetic hyperglycaemia. Diacylglycerol kinase (DGK) converts DG into phosphatidic acid. Therefore, it is expected that the activation of DGK would ameliorate DN. Indeed, it has been reported that vitamin E (VtE) ameliorates DN in rat by activating DGK, and we recently reported that VtE specifically activates DGKα isoform in vitro. However, whether DGKα is involved in the VtE-induced amelioration of DN in vivo remains unknown. Therefore, we investigated the VtE-induced amelioration of DN in wild-type (DGKα+/+) and DGKα–deficient (DGKα−/−) mice in which diabetes was induced by streptozocin. Several symptoms of DN were ameliorated by VtE treatment in the DGKα+/+ mice but not in the DGKα−/− mice. Moreover, transmission electron microscopy of glomeruli and immunofluorescent staining of glomerular epithelial cells (podocytes) indicated that VtE ameliorates podocyte pathology and prevents podocyte loss in the DGKα+/+ mice but not in the DGKα−/− mice. We showed that VtE can ameliorate DN in mice and that DGKα is involved in the VtE-induced amelioration of DN in vivo, suggesting that DGKα is an attractive therapeutic target for DN.
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17
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Xiao Y, Lin JB, Zhao YN, Liu JY, Xu PF. Exploring the Reactivity of Nitro-Activated 1,3-Enynes in an Organocatalytic One-Pot, Three-Component Coupling Reaction: A Tandem Catalytic Approach to a Novel 3-Nitrochroman Scaffold. Org Lett 2016; 18:6276-6279. [DOI: 10.1021/acs.orglett.6b03073] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Yu Xiao
- State Key Laboratory of Applied
Organic Chemistry, and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
| | - Jun-Bing Lin
- State Key Laboratory of Applied
Organic Chemistry, and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
| | - Yin-Na Zhao
- State Key Laboratory of Applied
Organic Chemistry, and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
| | - Jin-Yu Liu
- State Key Laboratory of Applied
Organic Chemistry, and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
| | - Peng-Fei Xu
- State Key Laboratory of Applied
Organic Chemistry, and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
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18
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Chen J, Feng X, Huang Q. Modulation of T-Bet and GATA-3 expression in experimental autoimmune thyroiditis rats through ginsenoside treatment. Endocr Res 2016; 41:28-33. [PMID: 26523790 DOI: 10.3109/07435800.2015.1066800] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Hashimoto's thyroiditis (HT) is one of the most common organ-specific autoimmune diseases. Increasing evidence indicates that HT may be characterized by an imbalance in the helper T cell subsets Th1 and Th2. Traditional Chinese Medicine (TCM) considers HT as a chronic exhaustion disease, leading to deficiency of qi. In TCM, qi indicates the functional power of the organs of the human body; hence TCM recommends focusing the treatment of HT so as to increase qi production. Ginseng is a well-known herbal medicine exhibiting a variety of efficacies, its main function-being to generate qi. Ginseng's principal active component is ginsenoside, and modern pharmacology has shown that ginsenoside demonstrates biphasic immunomodulatory effects that can be utilized for the treatment of immune disorders. Previous work demonstrated that ginsenoside has a therapeutic effect on HT, but its mechanism is unknown. Experimental autoimmune thyroiditis rats were produced in order to investigate whether ginsenoside can modulate Th1/Th2 imbalance, the direct objective being to examine modulation of IFN-γ and IL-4 by ELISA, and the gene and protein expression of T-bet and GATA-3 by real-time PCR and Western blot. IFN-γ levels were increased while IL-4 levels decreased in EAT rats; treatment with ginsenoside led to decreased peripheral blood IFN-γ levels, with low doses statistically significant. Ginsenoside produced a biphasic effect on IL-4, with low and moderate doses promoting and high doses inhibiting secretion. Both protein and mRNA levels of T-bet were markedly reduced, while GATA-3 was significantly increased by ginsenoside.
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Affiliation(s)
- Jie Chen
- a Department of Endocrinology , First Affiliated Hospital of Zhejiang Chinese Medical University , Hangzhou , China
| | - Xiaohong Feng
- a Department of Endocrinology , First Affiliated Hospital of Zhejiang Chinese Medical University , Hangzhou , China
| | - Qi Huang
- a Department of Endocrinology , First Affiliated Hospital of Zhejiang Chinese Medical University , Hangzhou , China
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19
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Wang PS, Liu P, Zhai YJ, Lin HC, Han ZY, Gong LZ. Asymmetric Allylic C–H Oxidation for the Synthesis of Chromans. J Am Chem Soc 2015; 137:12732-5. [DOI: 10.1021/jacs.5b08477] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Pu-Sheng Wang
- Hefei
National Laboratory for Physical Sciences at the Microscale and Department
of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Peng Liu
- Hefei
National Laboratory for Physical Sciences at the Microscale and Department
of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yu-Jia Zhai
- Hefei
National Laboratory for Physical Sciences at the Microscale and Department
of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Hua-Chen Lin
- Hefei
National Laboratory for Physical Sciences at the Microscale and Department
of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Zhi-Yong Han
- Hefei
National Laboratory for Physical Sciences at the Microscale and Department
of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Liu-Zhu Gong
- Hefei
National Laboratory for Physical Sciences at the Microscale and Department
of Chemistry, University of Science and Technology of China, Hefei 230026, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, China
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20
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Affiliation(s)
- Jean-Marc Zingg
- Department of Biochemistry and Molecular Biology, University of Miami, Miami, Florida 33136-6129;
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21
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Torres-Ayuso P, Daza-Martín M, Martín-Pérez J, Ávila-Flores A, Mérida I. Diacylglycerol kinase α promotes 3D cancer cell growth and limits drug sensitivity through functional interaction with Src. Oncotarget 2015; 5:9710-26. [PMID: 25339152 PMCID: PMC4259432 DOI: 10.18632/oncotarget.2344] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 08/11/2014] [Indexed: 02/02/2023] Open
Abstract
Diacylglycerol kinase (DGK)α converts diacylglycerol to phosphatidic acid. This lipid kinase sustains survival, migration and invasion of tumor cells, with no effect over untransformed cells, suggesting its potential as a cancer-specific target. Nonetheless the mechanisms that underlie DGKα specific contribution to cancer survival have not been elucidated. Using three-dimensional (3D) colon and breast cancer cell cultures, we demonstrate that DGKα upregulation is part of the transcriptional program that results in Src activation in these culture conditions. Pharmacological or genetic DGKα silencing impaired tumor growth in vivo confirming its function in malignant transformation. DGKα-mediated Src regulation contributed to limit the effect of Src inhibitors, and its transcriptional upregulation in response to PI3K/Akt inhibitors resulted in reduced toxicity. Src oncogenic properties and contribution to pharmacological resistance have been linked to its overactivation in cancer. DGKα participation in this central node helps to explain why its pharmacological inhibition or siRNA-mediated targeting specifically alters tumor viability with no effect on untransformed cells. Our results identify DGKα-mediated stabilization of Src activation as an important mechanism in tumor growth, and suggest that targeting this enzyme, alone or in combination with other inhibitors in wide clinical use, could constitute a treatment strategy for aggressive forms of cancer.
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Affiliation(s)
- Pedro Torres-Ayuso
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - Manuel Daza-Martín
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - Jorge Martín-Pérez
- Department of Cancer Biology, Instituto de Investigaciones Biomédicas Alberto Sols/CSIC, Universidad Autónoma de Madrid, Madrid, Spain
| | - Antonia Ávila-Flores
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - Isabel Mérida
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
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22
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Hayashi D, Ueda S, Yamanoue M, Saito N, Ashida H, Shirai Y. Epigallocatechin-3-gallate activates diacylglycerol kinase alpha via a 67 kDa laminin receptor: A possibility of galloylated catechins as functional food to prevent and/or improve diabetic renal dysfunctions. J Funct Foods 2015. [DOI: 10.1016/j.jff.2015.04.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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23
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Das L, Dey G, Chakraborty A. Investigation of the structures, potential energy surface, transition states and vibrational frequencies of a vitamin E precursor-chroman in S0 and S1 states: DFT based computational study. COMPUT THEOR CHEM 2014. [DOI: 10.1016/j.comptc.2014.10.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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24
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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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25
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Shirai Y, Ikeda M, Saito N. Regulation of diacylglycerol kinase by phosphorylation. Adv Biol Regul 2013; 52:239-47. [PMID: 22005481 DOI: 10.1016/j.advenzreg.2011.09.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 09/06/2011] [Indexed: 12/29/2022]
Affiliation(s)
- Y Shirai
- Applied Chemistry in Bioscience, Graduate School of Agriculture, Kobe 657 8501, Japan.
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26
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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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Sokolova TV, Rychkova MP, Voinova IV, Avrova NF. Dependence of protective effect of α-tocopherol on its concentration and time of action on pc12 cells under conditions of oxidative stress. J EVOL BIOCHEM PHYS+ 2011. [DOI: 10.1134/s0022093011050057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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28
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Lemaire-Ewing S, Lagrost L, Néel D. Lipid rafts: a signalling platform linking lipoprotein metabolism to atherogenesis. Atherosclerosis 2011; 221:303-10. [PMID: 22071358 DOI: 10.1016/j.atherosclerosis.2011.10.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 09/22/2011] [Accepted: 10/12/2011] [Indexed: 01/16/2023]
Abstract
Lipid rafts are microdomains of the plasma membrane which are enriched in cholesterol and sphingolipids. They serve as a platform for signal transduction, in particular during immune and inflammatory responses. As hypercholesterolemia and inflammation are two key elements of atherogenesis, it is conceivable that the cholesterol and cholesterol oxide content of lipid rafts might influence the inflammatory signalling pathways, thus modulating the development of atherosclerosis. In support of this emerging view, lipid rafts have been shown to be involved in several key steps of atherogenesis, such as the oxysterol-mediated apoptosis of vascular cells, the blunted ability of high density lipoproteins (HDL) to exert anti-inflammatory effects, and the exacerbated secretion of pro-inflammatory cytokines by immune cells. Additional studies are now required to address the relative contribution of lipid raft abnormalities to the pathophysiology of atherosclerosis and cardiovascular disease.
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Sokolova TV, Rychkova MP, Zakharova IO, Voynova IV, Avrova NF. Alpha-tocopherol at nanomolar concentrations increases the viability of PC12 cells under oxidative stress conditions. The effects of modulation of signaling systems. NEUROCHEM J+ 2011. [DOI: 10.1134/s181971241103007x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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30
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Vlasova YA, Avrova NF. Antioxidant effects of alpha-tocopherol at nanomolar concentrations: The role of the modulation of the activity of signaling systems. NEUROCHEM J+ 2010. [DOI: 10.1134/s1819712410030037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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31
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Lemaire-Ewing S, Desrumaux C, Néel D, Lagrost L. Vitamin E transport, membrane incorporation and cell metabolism: Is alpha-tocopherol in lipid rafts an oar in the lifeboat? Mol Nutr Food Res 2010; 54:631-40. [PMID: 20166147 DOI: 10.1002/mnfr.200900445] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Vitamin E is composed of closely related compounds, including tocopherols and tocotrienols. Studies of the last decade provide strong support for a specific role of alpha-tocopherol in cell signalling and the regulation of gene expression. It produces significant effects on inflammation, cell proliferation and apoptosis that are not shared by other vitamin E isomers with similar antioxidant properties. The different behaviours of vitamin E isomers might relate, at least in part, to the specific effects they exert at the plasma membrane. alpha-Tocopherol is not randomly distributed throughout the phospholipid bilayer of biological membranes, and as compared with other isomers, it shows a propensity to associate with lipid rafts. Distinct aspects of vitamin E transport and metabolism is discussed with emphasis on the interaction between alpha-tocopherol and lipid rafts and the consequences of these interactions on cell metabolism.
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32
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Affiliation(s)
- Jean-François F Dufour
- Institute of Clinical Pharmacology and Visceral Research, University of Bern, Bern, Switzerland
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33
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Müllebner A, Patel A, Stamberg W, Staniek K, Rosenau T, Netscher T, Gille L. Modulation of the Mitochondrial Cytochrome bc1 Complex Activity by Chromanols and Related Compounds. Chem Res Toxicol 2009; 23:193-202. [DOI: 10.1021/tx900333f] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Andrea Müllebner
- Molecular Pharmacology and Toxicology Unit, Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Veterinärplatz 1, A-1210 Vienna, Austria, Department of Chemistry, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria, and Research and Development, DSM Nutritional Products, P.O. Box 2676, CH-4002 Basel, Switzerland
| | - Anjan Patel
- Molecular Pharmacology and Toxicology Unit, Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Veterinärplatz 1, A-1210 Vienna, Austria, Department of Chemistry, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria, and Research and Development, DSM Nutritional Products, P.O. Box 2676, CH-4002 Basel, Switzerland
| | - Werner Stamberg
- Molecular Pharmacology and Toxicology Unit, Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Veterinärplatz 1, A-1210 Vienna, Austria, Department of Chemistry, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria, and Research and Development, DSM Nutritional Products, P.O. Box 2676, CH-4002 Basel, Switzerland
| | - Katrin Staniek
- Molecular Pharmacology and Toxicology Unit, Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Veterinärplatz 1, A-1210 Vienna, Austria, Department of Chemistry, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria, and Research and Development, DSM Nutritional Products, P.O. Box 2676, CH-4002 Basel, Switzerland
| | - Thomas Rosenau
- Molecular Pharmacology and Toxicology Unit, Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Veterinärplatz 1, A-1210 Vienna, Austria, Department of Chemistry, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria, and Research and Development, DSM Nutritional Products, P.O. Box 2676, CH-4002 Basel, Switzerland
| | - Thomas Netscher
- Molecular Pharmacology and Toxicology Unit, Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Veterinärplatz 1, A-1210 Vienna, Austria, Department of Chemistry, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria, and Research and Development, DSM Nutritional Products, P.O. Box 2676, CH-4002 Basel, Switzerland
| | - Lars Gille
- Molecular Pharmacology and Toxicology Unit, Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Veterinärplatz 1, A-1210 Vienna, Austria, Department of Chemistry, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria, and Research and Development, DSM Nutritional Products, P.O. Box 2676, CH-4002 Basel, Switzerland
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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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Brigelius-Flohé R. Vitamin E: the shrew waiting to be tamed. Free Radic Biol Med 2009; 46:543-54. [PMID: 19133328 DOI: 10.1016/j.freeradbiomed.2008.12.007] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 11/28/2008] [Accepted: 12/03/2008] [Indexed: 12/16/2022]
Abstract
Vitamin E is the last of all vitamins whose essentiality is not yet understood. Its widely accepted role as a lipophilic antioxidant has been questioned, since proof of its in vivo relevance remained scarce. The influence of vitamin E on biomarkers of oxidative stress in vivo is inconsistent and metabolites of vitamin E having reacted as an antioxidant are hardly detectable. Novel functions of vitamin E include the regulation of enzymes, most of which are membrane bound or activated by membrane recruitment. Also, expression of genes responds to vitamin E. The search for a transcription factor common to all regulated genes failed so far and a receptor that specifically binds vitamin E has not yet been identified. According to microarray data, pathways preferentially affected by the vitamin E status are the inflammatory response and cellular traffic. A role of vitamin E in cellular trafficking could best explain the neurological symptoms seen in vitamin E deficiency. Emerging knowledge on vitamin E is compiled here with the perspective to unravel the molecular mechanisms that could more likely explain the essentiality of the vitamin than its ability to scavenge free radicals.
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Affiliation(s)
- Regina Brigelius-Flohé
- German Institute of Human Nutrition Potsdam-Rehbruecke, Department of Biochemistry of Micronutrients, Nuthetal, Germany.
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36
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Topham MK, Epand RM. Mammalian diacylglycerol kinases: molecular interactions and biological functions of selected isoforms. Biochim Biophys Acta Gen Subj 2009; 1790:416-24. [PMID: 19364481 DOI: 10.1016/j.bbagen.2009.01.010] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Revised: 01/27/2009] [Accepted: 01/30/2009] [Indexed: 12/28/2022]
Abstract
The mammalian diacylglycerol kinases (DGK) are a group of enzymes having important roles in regulating many biological processes. Both the product and the substrate of these enzymes, i.e. diacylglycerol and phosphatidic acid, are important lipid signalling molecules. Each DGK isoform appears to have a distinct biological function as a consequence of its location in the cell and/or the proteins with which it associates. This review discusses three of the more extensively studied forms of this enzyme, DGKalpha, DGKvarepsilon, and DGKzeta. DGKalpha has an important role in immune function and its activity is modulated by several mechanisms. DGKvarepsilon has several unique features among which is its specificity for arachionoyl-containing substrates, suggesting its importance in phosphatidylinositol cycling. DGKzeta is expressed in many tissues and also has several mechanisms to regulate its functions. It is localized in several subcellular organelles, including the nucleus. The current state of our understanding of the properties and functions of these proteins is reviewed.
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Affiliation(s)
- Matthew K Topham
- Huntsman Cancer Institute, Department of Oncological Sciences, University of Utah, 2000 Circle of Hope, Salt Lake City, UT 84112, USA
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Decaffmeyer M, Shulga YV, Dicu AO, Thomas A, Truant R, Topham MK, Brasseur R, Epand RM. Determination of the topology of the hydrophobic segment of mammalian diacylglycerol kinase epsilon in a cell membrane and its relationship to predictions from modeling. J Mol Biol 2008; 383:797-809. [PMID: 18801368 DOI: 10.1016/j.jmb.2008.08.076] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Revised: 08/26/2008] [Accepted: 08/28/2008] [Indexed: 10/21/2022]
Abstract
The epsilon isoform of diacylglycerol kinase (DGKepsilon) is unique among mammalian DGKs in having a segment of hydrophobic amino acids comprising approximately residues 20 to 41. Several algorithms predict this segment to be a transmembrane (TM) helix. Using PepLook, we have performed an in silico analysis of the conformational preference of the segment in a hydrophobic environment comprising residues 18 to 42 of DGKepsilon. We find that there are two distinct groups of stable conformations, one corresponding to a straight helix that would traverse the membrane and the second corresponding to a bent helix that would enter and leave the same side of the membrane. Furthermore, the calculations predict that substituting the Pro32 residue in the hydrophobic segment with an Ala will cause the hydrophobic segment to favor a TM orientation. We have expressed the P32A mutant of DGKepsilon, with a FLAG tag (an N-terminal 3xFLAG epitope tag) at the amino terminus, in COS-7 cells. We find that this mutation causes a large reduction in both k(cat) and K(m) while maintaining k(cat)/K(m) constant. Specificity of the P32A mutant for substrates with polyunsaturated acyl chains is retained. The P32A mutant also has higher affinity for membranes since it is more difficult to extract from the membrane with high salt concentration or high pH compared with the wild-type DGKepsilon. We also evaluated the topology of the proteins with confocal immunofluorescence microscopy using NIH 3T3 cells. We find that the FLAG tag at the amino terminus of the wild-type enzyme is not reactive with antibodies unless the cell membrane is permeabilized with detergent. We also demonstrate that at least a fraction of the wild-type DGKepsilon is present in the plasma membrane and that comparable amounts of the wild-type and P32A mutant proteins are in the plasma membrane fraction. This indicates that in these cells the hydrophobic segment of the wild-type DGKepsilon is not TM but takes up a bent conformation. In contrast, the FLAG tag at the amino terminus of the P32A mutant is exposed to antibody both before and after membrane permeabilization. This modeling approach thus provides an explanation, not provided by simple predictive algorithms, for the observed topology of this protein in cell membranes. The work also demonstrates that the wild-type DGKepsilon is a monotopic protein.
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Affiliation(s)
- Marc Decaffmeyer
- Faculté Universitaire des Sciences Agronomiques de Gembloux, Centre de Biophysique Moléculaire Numérique, Passage des Déportés, 2, 5030 Gembloux, Belgium
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38
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Merino E, Avila-Flores A, Shirai Y, Moraga I, Saito N, Mérida I. Lck-dependent tyrosine phosphorylation of diacylglycerol kinase alpha regulates its membrane association in T cells. THE JOURNAL OF IMMUNOLOGY 2008; 180:5805-15. [PMID: 18424699 DOI: 10.4049/jimmunol.180.9.5805] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
TCR engagement triggers phospholipase Cgamma1 activation through the Lck-ZAP70-linker of activated T cell adaptor protein pathway. This leads to generation of diacylglycerol (DAG) and mobilization of intracellular Ca(2+), both essential for TCR-dependent transcriptional responses. TCR ligation also elicits transient recruitment of DAG kinase alpha (DGKalpha) to the lymphocyte plasma membrane to phosphorylate DAG, facilitating termination of DAG-regulated signals. The precise mechanisms governing dynamic recruitment of DGKalpha to the membrane have not been fully elucidated, although Ca(2+) influx and tyrosine kinase activation were proposed to be required. We show that DGKalpha is tyrosine phosphorylated, and identify tyrosine 335 (Y335), at the hinge between the atypical C1 domains and the catalytic region, as essential for membrane localization. Generation of an Ab that recognizes phosphorylated Y335 demonstrates Lck-dependent phosphorylation of endogenous DGKalpha during TCR activation and shows that pY335DGKalpha is a minor pool located exclusively at the plasma membrane. Our results identify Y335 as a residue critical for DGKalpha function and suggest a mechanism by which Lck-dependent phosphorylation and Ca(2+) elevation regulate DGKalpha membrane localization. The concerted action of these two signals results in transient, receptor-regulated DGKalpha relocalization to the site at which it exerts its function as a negative modulator of DAG-dependent signals.
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Affiliation(s)
- Ernesto Merino
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Cientificas, Madrid, Spain
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Hajiani M, Golestani A, Shariftabrizi A, Rastegar R, Payabvash S, Salmasi AH, Dehpour AR, Pasalar P. Dose-dependent modulation of systemic lipid peroxidation and activity of anti-oxidant enzymes by vitamin E in the rat. Redox Rep 2008; 13:60-6. [PMID: 18339248 DOI: 10.1179/135100008x259114] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The objective of this work was to examine the time-dependent pro-oxidant versus antioxidant effect of various doses of vitamin E used commonly in experimental studies. Erythrocyte activity of superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT) and plasma lipid peroxidation levels were investigated following biweekly intramuscular administration of 100, 300 and 600 mg/kg of vitamin E at a baseline time point, and additionally at 2, 4 and 6 weeks after initiating treatment. Vitamin E had an antioxidant effect when administered at low doses over short time periods, and increased the activity of antioxidant enzymes. At higher doses and over longer time periods, it increased the level of lipid peroxidation, and attenuated the activity of antioxidant enzymes. These results suggest that time-dependent variations in vitamin E effects should be considered in design and interpretation of experimental antioxidant studies, as well as during clinical trials.
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Affiliation(s)
- Maliheh Hajiani
- Department of Biochemistry, School of Medicine, Medical Sciences/University of Tehran, Tehran, Iran
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Atkinson J, Epand RF, Epand RM. Tocopherols and tocotrienols in membranes: a critical review. Free Radic Biol Med 2008; 44:739-64. [PMID: 18160049 DOI: 10.1016/j.freeradbiomed.2007.11.010] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Revised: 11/09/2007] [Accepted: 11/12/2007] [Indexed: 12/14/2022]
Abstract
The familiar role of tocols (tocopherols and tocotrienols) as lipid-soluble chain-terminating inhibitors of lipid peroxidation is currently in the midst of a reinterpretation. New biological activities have been described for tocols that apparently are not dependent on their well-established antioxidant behaviour. These activities could well be real, but there remain large gaps in our understanding of the behaviour of tocols in membranes, especially when it comes to the alpha-, beta-, gamma-, delta-chroman methylation patterns and the seemingly special nature of tocotrienols. It is inappropriate to make conclusions and develop models based on in vivo (or cell culture) results with reference to in vitro measurements of antioxidant activity. When present in biological membranes, tocols will experience a large variation in the local composition of phospholipids and the presence of neutral lipids such as cholesterol, both of which would be expected to change the efficiency of antioxidant action. It is likely that tocols are not homogeneously dispersed in a membrane, but it is still not known whether any specific combination of lipid head group and acyl chains are conferred special protection from peroxidation, nor do we currently appreciate the structural role that tocols play in membranes. Tocols may enhance curvature stress or counteract similar stresses generated by other lipids such as lysolipids. This review will outline what is known about the location and behaviour of tocols in phospholipid bilayers. We will draw mainly from the biophysical literature, but will attempt to extend the discussion to biologically relevant phenomena when appropriate. We hope that it will assist researchers when designing new experiments and when critically assessing the results, in turn providing a more thorough understanding of the biochemistry of tocols.
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Affiliation(s)
- Jeffrey Atkinson
- Department of Chemistry and Centre for Biotechnology, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario, Canada.
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Abstract
DGKs (diacylglycerol kinases) are members of a unique and conserved family of intracellular lipid kinases that phosphorylate DAG (diacylglycerol), catalysing its conversion into PA (phosphatidic acid). This reaction leads to attenuation of DAG levels in the cell membrane, regulating a host of intracellular signalling proteins that have evolved the ability to bind this lipid. The product of the DGK reaction, PA, is also linked to the regulation of diverse functions, including cell growth, membrane trafficking, differentiation and migration. In multicellular eukaryotes, DGKs provide a link between lipid metabolism and signalling. Genetic experiments in Caenorhabditis elegans, Drosophila melanogaster and mice have started to unveil the role of members of this protein family as modulators of receptor-dependent responses in processes such as synaptic transmission and photoreceptor transduction, as well as acquired and innate immune responses. Recent discoveries provide new insights into the complex mechanisms controlling DGK activation and their participation in receptor-regulated processes. After more than 50 years of intense research, the DGK pathway emerges as a key player in the regulation of cell responses, offering new possibilities of therapeutic intervention in human pathologies, including cancer, heart disease, diabetes, brain afflictions and immune dysfunctions.
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Merino E, Sanjuán MA, Moraga I, Ciprés A, Mérida I. Role of the diacylglycerol kinase alpha-conserved domains in membrane targeting in intact T cells. J Biol Chem 2007; 282:35396-404. [PMID: 17911109 DOI: 10.1074/jbc.m702085200] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Diacylglycerol kinase (DGK) phosphorylates diacylglycerol to phosphatidic acid, modifying the cellular levels of these two lipid mediators. Ten DGK isoforms, grouped into five subtypes, are found in higher organisms. All contain a conserved C-terminal domain and at least two cysteine-rich motifs of unknown function. DGKalpha is a type I enzyme that acts as a negative modulator of diacylglycerol-based signals during T cell activation. Here we studied the functional role of the DGKalpha domains using mutational analysis to investigate membrane binding in intact cells. We show that the two atypical C1 domains are essential for plasma membrane targeting of the protein in intact cells but unnecessary for catalytic activity. We also identify the C-terminal sequence of the protein as essential for membrane binding in a phosphatidic acid-dependent manner. Finally we demonstrate that, in the absence of the calcium binding domain, receptor-dependent translocation of the truncated protein is regulated by phosphorylation of Tyr(335). This functional study provides new insight into the role of the so-called conserved domains of this lipid kinase family and demonstrates the existence of additional domains that confer specific plasma membrane localization to this particular isoform.
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Affiliation(s)
- Ernesto Merino
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid, Spain
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Baldanzi G, Cutrupi S, Chianale F, Gnocchi V, Rainero E, Porporato P, Filigheddu N, van Blitterswijk WJ, Parolini O, Bussolino F, Sinigaglia F, Graziani A. Diacylglycerol kinase-alpha phosphorylation by Src on Y335 is required for activation, membrane recruitment and Hgf-induced cell motility. Oncogene 2007; 27:942-56. [PMID: 17700527 DOI: 10.1038/sj.onc.1210717] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Diacylglycerol (DAG) kinases (Dgk), which phosphorylate DAG to generate phosphatidic acid, act as either positive or negative key regulators of cell signaling. We previously showed that Src mediates growth factors-induced activation of Dgk-alpha, whose activity is required for cell motility, proliferation and angiogenesis. Here, we demonstrate that both hepatocytes growth factor (HGF) stimulation and v-Src transformation induce tyrosine phosphorylation of Dgk-alpha on Y335, through a mechanism requiring its proline-rich C-terminal sequence. Moreover, we show that both proline-rich sequence and phosphorylation of Y335 of Dgk-alpha mediate: (i) its enzymatic activation, (ii) its ability to interact respectively with SH3 and SH2 domains of Src, (iii) its recruitment to the membrane. In addition, we show that phosphorylation of Dgk-alpha on Y335 is required for HGF-induced motility, while its constitutive recruitment at the membrane by myristylation is sufficient to trigger spontaneous motility in absence of HGF. Providing the first evidence that tyrosine phosphorylation of Dgk-alpha is required for growth-factors-induced activation and membrane recruitment, these findings underscore its relevance as a rheostat, whose activation is a threshold to elicit growth factors-induced migratory signaling.
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Affiliation(s)
- G Baldanzi
- Department of Medical Sciences, University Amedeo Avogadro of Piemonte Oriental, Novara, Italy
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Miele C, Paturzo F, Teperino R, Sakane F, Fiory F, Oriente F, Ungaro P, Valentino R, Beguinot F, Formisano P. Glucose regulates diacylglycerol intracellular levels and protein kinase C activity by modulating diacylglycerol kinase subcellular localization. J Biol Chem 2007; 282:31835-43. [PMID: 17675299 DOI: 10.1074/jbc.m702481200] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although chronic hyperglycemia reduces insulin sensitivity and leads to impaired glucose utilization, short term exposure to high glucose causes cellular responses positively regulating its own metabolism. We show that exposure of L6 myotubes overexpressing human insulin receptors to 25 mm glucose for 5 min decreased the intracellular levels of diacylglycerol (DAG). This was paralleled by transient activation of diacylglycerol kinase (DGK) and of insulin receptor signaling. Following 30-min exposure, however, both DAG levels and DGK activity returned close to basal levels. Moreover, the acute effect of glucose on DAG removal was inhibited by >85% by the DGK inhibitor R59949. DGK inhibition was also accompanied by increased protein kinase C-alpha (PKCalpha) activity, reduced glucose-induced insulin receptor activation, and GLUT4 translocation. Glucose exposure transiently redistributed DGK isoforms alpha and delta, from the prevalent cytosolic localization to the plasma membrane fraction. However, antisense silencing of DGKdelta, but not of DGKalpha expression, was sufficient to prevent the effect of high glucose on PKCalpha activity, insulin receptor signaling, and glucose uptake. Thus, the short term exposure of skeletal muscle cells to glucose causes a rapid induction of DGK, followed by a reduction of PKCalpha activity and transactivation of the insulin receptor signaling. The latter may mediate, at least in part, glucose induction of its own metabolism.
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Affiliation(s)
- Claudia Miele
- Dipartimento di Biologia e Patologia Cellulare e Molecolare & Istituto di Endocrinologia ed Oncologia Sperimentale del CNR, Federico II University of Naples, Via Pansini 5, Naples 80131, Italy
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Sakane F, Imai SI, Kai M, Yasuda S, Kanoh H. Diacylglycerol kinases: Why so many of them? Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1771:793-806. [PMID: 17512245 DOI: 10.1016/j.bbalip.2007.04.006] [Citation(s) in RCA: 247] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Revised: 03/28/2007] [Accepted: 04/06/2007] [Indexed: 11/17/2022]
Abstract
Diacylglycerol (DAG) kinase (DGK) modulates the balance between the two signaling lipids, DAG and phosphatidic acid (PA), by phosphorylating DAG to yield PA. To date, ten mammalian DGK isozymes have been identified. In addition to the C1 domains (protein kinase C-like zinc finger structures) conserved commonly in all DGKs, these isoforms possess a variety of regulatory domains of known and/or predicted functions, such as a pair of EF-hand motifs, a pleckstrin homology domain, a sterile alpha motif domain and ankyrin repeats. Beyond our expectations, recent studies have revealed that DGK isozymes play pivotal roles in a wide variety of signal transduction pathways conducting development, neural and immune responses, cytoskeleton reorganization and carcinogenesis. Moreover, there has been rapidly growing evidence indicating that individual DGK isoforms exert their specific roles through interactions with unique partner proteins such as protein kinase Cs, Ras guanyl nucleotide-releasing protein, chimaerins and phosphatidylinositol-4-phosphate 5-kinase. Therefore, an emerging paradigm for DGK is that the individual DGK isoforms assembled in their own signaling complexes should carry out spatio-temporally segregated tasks for a wide range of biological processes via regulating local, but not global, concentrations of DAG and/or PA.
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Affiliation(s)
- Fumio Sakane
- Department of Biochemistry, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo 060-8556, Japan.
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46
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Zingg JM. Modulation of signal transduction by vitamin E. Mol Aspects Med 2007; 28:481-506. [PMID: 17320164 DOI: 10.1016/j.mam.2006.12.009] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Accepted: 12/16/2006] [Indexed: 01/22/2023]
Abstract
The ability of vitamin E to modulate signal transduction and gene expression has been observed in numerous studies; however, the detailed molecular mechanisms involved are often not clear. The eight natural vitamin E analogues and synthetic derivatives affect signal transduction with different potency, possibly reflecting their different ability to interact with specific proteins. Vitamin E modulates the activity of several enzymes involved in signal transduction, such as protein kinase C, protein kinase B, protein tyrosine kinases, 5-, 12-, and 15-lipoxygenases, cyclooxygenase-2, phospholipase A2, protein phosphatase 2A, protein tyrosine phosphatase, and diacylglycerol kinase. Activation of some these enzymes after stimulation of cell surface receptors with growth factors or cytokines can be normalized by vitamin E. At the molecular level, the translocation of several of these enzymes to the plasma membrane is affected by vitamin E, suggesting that the modulation of protein-membrane interactions may be a common theme for vitamin E action. In this review the main effects of vitamin E on enzymes involved in signal transduction are summarized and the possible mechanisms leading to enzyme modulation evaluated. The elucidation of the molecular and cellular events affected by vitamin E could reveal novel strategies and molecular targets for developing similarly acting compounds.
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Affiliation(s)
- Jean-Marc Zingg
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland.
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Olenchock BA, Guo R, Carpenter JH, Jordan M, Topham MK, Koretzky GA, Zhong XP. Disruption of diacylglycerol metabolism impairs the induction of T cell anergy. Nat Immunol 2006; 7:1174-81. [PMID: 17028587 DOI: 10.1038/ni1400] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Accepted: 09/13/2006] [Indexed: 12/18/2022]
Abstract
Anergic T cells have altered diacylglycerol metabolism, but whether that altered metabolism has a causative function in the induction of T cell anergy is not apparent. To test the importance of diacylglycerol metabolism in T cell anergy, we manipulated diacylglycerol kinases (DGKs), which are enzymes that terminate diacylglycerol-dependent signaling. Overexpression of DGK-alpha resulted in a defect in T cell receptor signaling that is characteristic of anergy. We generated DGK-alpha-deficient mice and found that DGK-alpha-deficient T cells had more diacylglycerol-dependent T cell receptor signaling. In vivo anergy induction was impaired in DGK-alpha-deficient mice. When stimulated in anergy-producing conditions, T cells lacking DGK-alpha or DGK-zeta proliferated and produced interleukin 2. Pharmacological inhibition of DGK-alpha activity in DGK-zeta-deficient T cells that received an anergizing stimulus proliferated similarly to wild-type T cells that received CD28 costimulation and prevented anergy induction. Our findings suggest that regulation of diacylglycerol metabolism is critical in determining whether activation or anergy ensues after T cell receptor stimulation.
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Affiliation(s)
- Benjamin A Olenchock
- Signal Transduction Program, Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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