1
|
Li J, Yao S, Kim SC, Wang X. Lipid phosphorylation by a diacylglycerol kinase suppresses ABA biosynthesis to regulate plant stress responses. MOLECULAR PLANT 2024; 17:342-358. [PMID: 38243594 PMCID: PMC10869644 DOI: 10.1016/j.molp.2024.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 12/08/2023] [Accepted: 01/05/2024] [Indexed: 01/21/2024]
Abstract
Lipid phosphorylation by diacylglycerol kinase (DGK) that produces phosphatidic acid (PA) plays important roles in various biological processes, including stress responses, but the underlying mechanisms remain elusive. Here, we show that DGK5 and its lipid product PA suppress ABA biosynthesis by interacting with ABA-DEFICIENT 2 (ABA2), a key ABA biosynthesis enzyme, to negatively modulate plant response to abiotic stress tested in Arabidopsis thaliana. Loss of DGK5 function rendered plants less damaged, whereas overexpression (OE) of DGK5 enhanced plant damage to water and salt stress. The dgk5 mutant plants exhibited decreased total cellular and nuclear levels of PA with increased levels of diacylglycerol, whereas DGK5-OE plants displayed the opposite effect. Interestingly, we found that both DGK5 and PA bind to the ABA-synthesizing enzyme ABA2 and suppress its enzymatic activity. Consistently, the dgk5 mutant plants exhibited increased levels of ABA, while DGK5-OE plants showed reduced ABA levels. In addition, we showed that both DGK5 and ABA2 are detected in and outside the nuclei, and loss of DGK5 function decreased the nuclear association of ABA2. We found that both DGK5 activity and PA promote nuclear association of ABA2. Taken together, these results indicate that both DGK5 and PA interact with ABA2 to inhibit its enzymatic activity and promote its nuclear sequestration, thereby suppressing ABA production in response to abiotic stress. Our study reveals a sophisticated mechanism by which DGK5 and PA regulate plant stress responses.
Collapse
Affiliation(s)
- Jianwu Li
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Shuaibing Yao
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Sang-Chul Kim
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Xuemin Wang
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA.
| |
Collapse
|
2
|
Su H, Guo H, Qiu X, Lin TY, Qin C, Celio G, Yong P, Senders M, Han X, Bernlohr DA, Chen X. Lipocalin 2 regulates mitochondrial phospholipidome remodeling, dynamics, and function in brown adipose tissue in male mice. Nat Commun 2023; 14:6729. [PMID: 37872178 PMCID: PMC10593768 DOI: 10.1038/s41467-023-42473-2] [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: 11/17/2022] [Accepted: 10/11/2023] [Indexed: 10/25/2023] Open
Abstract
Mitochondrial function is vital for energy metabolism in thermogenic adipocytes. Impaired mitochondrial bioenergetics in brown adipocytes are linked to disrupted thermogenesis and energy balance in obesity and aging. Phospholipid cardiolipin (CL) and phosphatidic acid (PA) jointly regulate mitochondrial membrane architecture and dynamics, with mitochondria-associated endoplasmic reticulum membranes (MAMs) serving as the platform for phospholipid biosynthesis and metabolism. However, little is known about the regulators of MAM phospholipid metabolism and their connection to mitochondrial function. We discover that LCN2 is a PA binding protein recruited to the MAM during inflammation and metabolic stimulation. Lcn2 deficiency disrupts mitochondrial fusion-fission balance and alters the acyl-chain composition of mitochondrial phospholipids in brown adipose tissue (BAT) of male mice. Lcn2 KO male mice exhibit an increase in the levels of CLs containing long-chain polyunsaturated fatty acids (LC-PUFA), a decrease in CLs containing monounsaturated fatty acids, resulting in mitochondrial dysfunction. This dysfunction triggers compensatory activation of peroxisomal function and the biosynthesis of LC-PUFA-containing plasmalogens in BAT. Additionally, Lcn2 deficiency alters PA production, correlating with changes in PA-regulated phospholipid-metabolizing enzymes and the mTOR signaling pathway. In conclusion, LCN2 plays a critical role in the acyl-chain remodeling of phospholipids and mitochondrial bioenergetics by regulating PA production and its function in activating signaling pathways.
Collapse
Affiliation(s)
- Hongming Su
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, MN, 55108, USA
| | - Hong Guo
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, MN, 55108, USA
| | - Xiaoxue Qiu
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, MN, 55108, USA
| | - Te-Yueh Lin
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, MN, 55108, USA
| | - Chao Qin
- Barshop Institute for Longevity and Aging Studies, Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229-3900, USA
| | - Gail Celio
- University Imaging Centers, University of Minnesota-Twin Cities, Minneapolis, MN, 55455, USA
| | - Peter Yong
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota-Twin Cities, Minneapolis, MN, 55455, USA
| | - Mark Senders
- University Imaging Centers, University of Minnesota-Twin Cities, Minneapolis, MN, 55455, USA
| | - Xianlin Han
- Barshop Institute for Longevity and Aging Studies, Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229-3900, USA
| | - David A Bernlohr
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota-Twin Cities, Minneapolis, MN, 55455, USA
| | - Xiaoli Chen
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, MN, 55108, USA.
| |
Collapse
|
3
|
Zhang Y, Ma K, Jiang L, Xu L, Luo Y, Wu J, Li Y. Revealing the Preventable Effects of Fu-Zheng-Qu-Xie Decoction against Recurrence and Metastasis of Postoperative Early-Stage Lung Adenocarcinoma Based on Network Pharmacology Coupled with Metabolomics Analysis. ACS OMEGA 2023; 8:35555-35570. [PMID: 37810735 PMCID: PMC10552138 DOI: 10.1021/acsomega.3c00122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Accepted: 06/27/2023] [Indexed: 10/10/2023]
Abstract
Fu-Zheng-Qu-Xie (FZQX) decoction is a traditional Chinese herbal prescription for the treatment of lung cancer and exerts proapoptotic and immunomodulatory effects. It has been clinically suggested to be effective in improving the survival of postoperative early-stage lung adenocarcinoma (LUAD), but the mechanism remains unclear. In this study, we used network pharmacology coupled with metabolomics approaches to explore the pharmacological action and effective mechanism of FZQX against the recurrence and metastasis of postoperative early-stage LUAD. Network pharmacology analysis showed that FZQX could prevent the recurrence and metastasis of postoperative early-stage LUAD by regulating a series of targets involving vascular endothelial growth factor receptor 2, estrogen receptor 1, sarcoma gene, epidermal growth factor receptor, and protein kinase B and by influencing the Ras, PI3K-Akt, and mitogen-activated protein kinase signaling pathways. In liquid chromatography-mass spectrometry analysis, 11 differentially expressed metabolites, including PA(12:0/18:4(6Z,9Z,12Z,15Z)), PC(16:0/0:0)[U], LysoPC(18:1(11Z)), and LysoPC(18:0), were discovered in the FZQX-treated group compared to those in the model group before treatment or normal group. They were enriched in cancer metabolism-related signaling pathways such as central carbon metabolism in cancer, choline metabolism, and glycerol phospholipid metabolism. Collectively, our results suggest that the multicomponent and multitarget interaction network of FZQX inhibits the recurrence and metastasis of postoperative early-stage LUAD by activating the receptor signal transduction pathway to inhibit proliferation, induce cell apoptosis, inhibit aerobic glycolysis, and reprogram tumor lipid metabolism.
Collapse
Affiliation(s)
- Yixi Zhang
- Department
of Oncology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200071, China
| | - Kai Ma
- Department
of Oncology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200071, China
| | - Lei Jiang
- Department
of Thoracic Surgery, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, China
| | - Lili Xu
- Department
of Oncology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200071, China
| | - Yingbin Luo
- Department
of Oncology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200071, China
| | - Jianchun Wu
- Department
of Oncology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200071, China
| | - Yan Li
- Department
of Oncology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200071, China
| |
Collapse
|
4
|
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]
|
5
|
Hoshino F, Nakayama M, Furuta M, Murakami C, Kato A, Sakane F. Phosphatidylinositol 4,5-bisphosphate-specific phospholipase C β1 selectively binds dipalmitoyl and distearoyl phosphatidic acids via Lys946 and Lys951. Lipids 2022; 57:289-302. [PMID: 36054018 DOI: 10.1002/lipd.12356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/31/2022] [Accepted: 08/15/2022] [Indexed: 11/09/2022]
Abstract
Phospholipase C (PLC) β1 hydrolyzes 1-stearoyl-2-arachidonoyl (18:0/20:4)-phosphatidylinositol (PtdIns) 4,5-bisphosphate to produce diacylglycerol, which is converted to phosphatidic acid (PtdOH), in the PtdIns cycle and plays pivotal roles in intracellular signal transduction. The present study identified PLCβ1 as a PtdOH-binding protein using PtdOH-containing liposomes. Moreover, the comparison of the binding of PLCβ1 to various PtdOH species, including 14:0/14:0-PtdOH, 16:0/16:0-PtdOH, 16:0/18:1-PtdOH, 18:0/18:1-PtdOH, 18:0/18:0-PtdOH, 18:1/18:1-PtdOH, 18:0/20:4-PtdOH, and 18:0/22:6-PtdOH, indicated that the interaction of PLCβ1 with 16:0/16:0-PtdOH was the strongest. The PLCβ1-binding activity of 18:0/18:0-PtdOH was almost the same as the binding activity of 16:0/16:0-PtdOH. Furthermore, the binding of PLCβ1 to 16:0/16:0-PtdOH was substantially stronger than 16:0/16:0-phosphatidylserine, 16:0/16:0/16:0/16:0-cardiolipin, 16:0/16:0-PtdIns, and 18:0/20:4-PtdIns. We revealed that a PLCβ1 mutant whose Lys946 and Lys951 residues were replaced with Glu (PLCβ1-KE) did not interact with 16:0/16:0-PtdOH and failed to localize to the plasma membrane in Neuro-2a cells. Retinoic acid-dependent increase in neurite length and numbers was significantly inhibited in PLCβ1-expressing cells; however, this considerable attenuation was not detected in the cells expressing PLCβ1-KE. Overall, these results strongly suggest that PtdOHs containing only saturated fatty acids, including 16:0/16:0-PtdOH, which are not derived from the PtdIns cycle, selectively bind to PLCβ1 and regulate its function.
Collapse
Affiliation(s)
- Fumi Hoshino
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Maika Nakayama
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Masataka Furuta
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Chiaki Murakami
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan.,Institute for Advanced Academic Research, Chiba University, Chiba, Japan
| | - Ayumu Kato
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| |
Collapse
|
6
|
Diacylglycerol kinase η regulates cell proliferation and its levels are elevated by glucocorticoids in undifferentiated neuroblastoma cells. Biochem Biophys Res Commun 2022; 602:41-48. [DOI: 10.1016/j.bbrc.2022.02.100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/21/2022] [Accepted: 02/24/2022] [Indexed: 11/18/2022]
|
7
|
Rocchetti G, Vitali M, Zappaterra M, Righetti L, Sirri R, Lucini L, Dall’Asta C, Davoli R, Galaverna G. A molecular insight into the lipid changes of pig Longissimus thoracis muscle following dietary supplementation with functional ingredients. PLoS One 2022; 17:e0264953. [PMID: 35324931 PMCID: PMC8947141 DOI: 10.1371/journal.pone.0264953] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 02/20/2022] [Indexed: 11/29/2022] Open
Abstract
In this work, the Longissimus thoracis pig skeletal muscle was used as a model to investigate the impact of two different diets, supplemented with n-3 polyunsaturated fatty acids from extruded linseed (L) and polyphenols from grape skin and oregano extracts (L+P), on the lipidomic profile of meat. A standard diet for growing-finishing pigs (CTRL) was used as a control. Changes in lipids profile were investigated through an untargeted lipidomics and transcriptomics combined investigation. The lipidomics identified 1507 compounds, with 195 compounds fitting with the MS/MS spectra of LipidBlast database. When compared with the CTRL group, the L+P diet significantly increased 15 glycerophospholipids and 8 sphingolipids, while the L diet determined a marked up-accumulation of glycerolipids. According to the correlations outlined between discriminant lipids and genes, the L diet may act preventing adipogenesis and the related inflammation processes, while the L+P diet promoted the expression of genes involved in lipids' biosynthesis and adipogenic extracellular matrix formation and functioning.
Collapse
Affiliation(s)
- Gabriele Rocchetti
- Department of Animal Science, Food and Nutrition, Università Cattolica del Sacro Cuore, Piacenza, Italy
| | - Marika Vitali
- Interdepartmental centre for Industrial Agrifood research (CIRI-AGRO)—Università di Bologna, Cesena, Italy
- Department of Agricultural and Food sciences (DISTAL), Alma Mater Studiorum–Università di Bologna, Bologna, Italy
| | - Martina Zappaterra
- Department of Agricultural and Food sciences (DISTAL), Alma Mater Studiorum–Università di Bologna, Bologna, Italy
| | - Laura Righetti
- Department of Food and Drug, Parco Area delle Scienze, Parma, Italy
| | - Rubina Sirri
- Interdepartmental centre for Industrial Agrifood research (CIRI-AGRO)—Università di Bologna, Cesena, Italy
- Department of Agricultural and Food sciences (DISTAL), Alma Mater Studiorum–Università di Bologna, Bologna, Italy
| | - Luigi Lucini
- Department for Sustainable Food Process, Università Cattolica del Sacro Cuore, Piacenza, Italy
| | - Chiara Dall’Asta
- Department of Food and Drug, Parco Area delle Scienze, Parma, Italy
| | - Roberta Davoli
- Interdepartmental centre for Industrial Agrifood research (CIRI-AGRO)—Università di Bologna, Cesena, Italy
- Department of Agricultural and Food sciences (DISTAL), Alma Mater Studiorum–Università di Bologna, Bologna, Italy
| | - Gianni Galaverna
- Department of Food and Drug, Parco Area delle Scienze, Parma, Italy
| |
Collapse
|
8
|
Nakano T, Tanaka T, Sakane F, Kaneko MK, Kato Y, Goto K. Immunocytochemical Analysis of DGKη in Cultured Cells Using a Monoclonal Antibody DhMab-4. Monoclon Antib Immunodiagn Immunother 2021; 40:261-265. [PMID: 34958278 DOI: 10.1089/mab.2021.0034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Diacylglycerol kinase (DGK) is a lipid kinase that converts diacylglycerol (DG) to phosphatidic acid (PA). Since both DG and PA serve as intracellular second messenger molecules, DGK plays a pivotal role in balancing these two signaling pathways. Of the DGK family, DGKη is classified as a type II DGK. Reportedly, DGKη is expressed ubiquitously through mammalian tissues and cells. Previous studies using cDNA transfection methods reported cytoplasmic localization of DGKη in cultured human cells. However, subcellular localization of native protein is still unknown. Recently, we established a human DGKη-specific monoclonal antibody, DhMab-4. In this study, we examined subcellular localization of native protein of DGKη using DhMab-4 by immunocytochemistry in human cultured cells.
Collapse
Affiliation(s)
- Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University Faculty of Medicine, Yamagata, Japan
| | - Toshiaki Tanaka
- Department of Anatomy and Cell Biology, Yamagata University Faculty of Medicine, Yamagata, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Mika K Kaneko
- Department of Antibody Drug Development and Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yukinari Kato
- Department of Antibody Drug Development and Tohoku University Graduate School of Medicine, Sendai, Japan
- Department of Molecular Pharmacology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Kaoru Goto
- Department of Anatomy and Cell Biology, Yamagata University Faculty of Medicine, Yamagata, Japan
| |
Collapse
|
9
|
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.
Collapse
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;
| |
Collapse
|
10
|
Asami M, Suzuki Y, Sakane F. Dopamine and the phosphorylated dopamine transporter are increased in the diacylglycerol kinase η-knockout mouse brain. FEBS Lett 2021; 595:1313-1321. [PMID: 33599293 DOI: 10.1002/1873-3468.14059] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 01/26/2021] [Accepted: 02/09/2021] [Indexed: 12/19/2022]
Abstract
The molecular mechanisms generating the mania-like abnormal behaviors caused by diacylglycerol (DG) kinase (DGK) η deficiency remain unclear. Here, we found that DGKη knockout markedly increased dopamine (DA) levels in the midbrain (DA-producing region, 2.8-fold) and cerebral cortex (DA projection region, 1.2-fold). Moreover, DGKη deficiency significantly augmented phosphorylated DA transporter (DAT) levels (1.4-fold increase), which induce DA efflux to the synaptic cleft, in the cerebral cortex. Moreover, phosphorylation levels of protein kinase C-β, which is activated by DG and involved in DAT phosphorylation, were also increased. DAT expressed in Neuro-2a cells recruited DGKη to the plasma membrane and colocalized with it. These results strongly suggest that dopaminergic hyperfunction caused by DGKη deficiency in the brain leads to mania-like behaviors.
Collapse
Affiliation(s)
- Maho Asami
- Department of Chemistry, Graduate School of Science, Chiba University, Japan
| | - Yuji Suzuki
- Department of Chemistry, Graduate School of Science, Chiba University, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Japan
| |
Collapse
|
11
|
Ishizaki A, Murakami C, Yamada H, Sakane F. Diacylglycerol Kinase η Activity in Cells Using Protein Myristoylation and Cellular Phosphatidic Acid Sensor. Lipids 2021; 56:449-458. [PMID: 33624314 DOI: 10.1002/lipd.12301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 02/02/2021] [Accepted: 02/09/2021] [Indexed: 12/26/2022]
Abstract
Diacylglycerol kinase (DGK) phosphorylates diacylglycerol to produce phosphatidic acid (PtdOH) and regulates the balance between two lipid second messengers: diacylglycerol and PtdOH. Several lines of evidence suggest that the η isozyme of DGK is involved in the pathogenesis of bipolar disorder. However, the detailed molecular mechanisms regulating the pathophysiological functions remain unclear. One reason is that it is difficult to detect the cellular activity of DGKη. To overcome this difficulty, we utilized protein myristoylation and a cellular PtdOH sensor, the N-terminal region of α-synuclein (α-Syn-N). Although DGKη expressed in COS-7 cells was broadly distributed in the cytoplasm, myristoylated (Myr)-AcGFP-DGKη and Myr-AcGFP-DGKη-KD (inactive (kinase-dead) mutant) were substantially localized in the plasma membrane. Moreover, DsRed monomer-α-Syn-N significantly colocalized with Myr-AcGFP-DGKη but not Myr-AcGFP-DGKη-KD at the plasma membrane. When COS-7 cells were osmotically shocked, all DGKη constructs were exclusively translocated to osmotic shock-responsive granules (OSRG). DsRed monomer-α-Syn-N markedly colocalized with only Myr-AcGFP-DGKη at OSRG and exhibited a higher signal/background ratio (3.4) than Myr-AcGFP-DGKη at the plasma membrane in unstimulated COS-7 cells (2.5), indicating that α-Syn-N more effectively detects Myr-AcGFP-DGKη activity in OSRG. Therefore, these results demonstrated that the combination of myristoylation and the PtdOH sensor effectively detects DGKη activity in cells and that this method is convenient to examine the molecular functions of DGKη. Moreover, this method will be useful for the development of drugs targeting DGKη. Furthermore, the combination of myristoylation (intensive accumulation in membranes) and α-Syn-N can be applicable to assays for various cytosolic PtdOH-generating enzymes.
Collapse
Affiliation(s)
- Ayuka Ishizaki
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Chiaki Murakami
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Haruka Yamada
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| |
Collapse
|
12
|
Sánchez-Sandoval ME, Racagni Di-Palma GE, González-Mendoza VM, Cab-Guillén YA, Muñoz-Sanchez JA, Ramos-Díaz A, Hernández-Sotomayor SMT. Phospholipid signaling pathway in Capsicum chinense suspension cells as a key response to consortium infection. BMC PLANT BIOLOGY 2021; 21:62. [PMID: 33494714 PMCID: PMC7836502 DOI: 10.1186/s12870-021-02830-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 01/07/2021] [Indexed: 05/04/2023]
Abstract
BACKGROUND Mexico is considered the diversification center for chili species, but these crops are susceptible to infection by pathogens such as Colletotrichum spp., which causes anthracnose disease and postharvest decay in general. Studies have been carried out with isolated strains of Colletotrichum in Capsicum plants; however, under growing conditions, microorganisms generally interact with others, resulting in an increase or decrease of their ability to infect the roots of C. chinense seedlings and thus, cause disease. RESULTS Morphological changes were evident 24 h after inoculation (hai) with the microbial consortium, which consisted primarily of C. ignotum. High levels of diacylglycerol pyrophosphate (DGPP) and phosphatidic acid (PA) were found around 6 hai. These metabolic changes could be correlated with high transcription levels of diacylglycerol-kinase (CchDGK1 and CchDG31) at 3, 6 and 12 hai and also to pathogen gene markers, such as CchPR1 and CchPR5. CONCLUSIONS Our data constitute the first evidence for the phospholipids signalling events, specifically DGPP and PA participation in the phospholipase C/DGK (PI-PLC/DGK) pathway, in the response of Capsicum to the consortium, offering new insights on chilis' defense responses to damping-off diseases.
Collapse
Affiliation(s)
- María E Sánchez-Sandoval
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, Mérida, Yucatán, Mexico
| | | | - Victor M González-Mendoza
- CONA CYT- Centro de Investigación y Desarrollo en Agrobiotecnología Alimentaria (Consortium between Centro de Investigación y Desarrollo, A.C. and Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco), San Agustín Tlaxiaca, Hidalgo, Mexico
| | - Yahaira A Cab-Guillén
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, Mérida, Yucatán, Mexico
| | - José A Muñoz-Sanchez
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, Mérida, Yucatán, Mexico
| | - Ana Ramos-Díaz
- Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco (CIATEJ), Subsede Sureste, Yucatán, Mexico
| | - S M Teresa Hernández-Sotomayor
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, Mérida, Yucatán, Mexico.
| |
Collapse
|
13
|
Auclair N, Sané AT, Delvin E, Spahis S, Levy E. Phospholipase D as a Potential Modulator of Metabolic Syndrome: Impact of Functional Foods. Antioxid Redox Signal 2021; 34:252-278. [PMID: 32586106 DOI: 10.1089/ars.2020.8081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Significance: Cardiometabolic disorders (CMD) are composed of a plethora of metabolic dysfunctions such as dyslipidemia, nonalcoholic fatty liver disease, insulin resistance, and hypertension. The development of these disorders is highly linked to inflammation and oxidative stress (OxS), two metabolic states closely related to physiological and pathological conditions. Given the drastically rising CMD prevalence, the discovery of new therapeutic targets/novel nutritional approaches is of utmost importance. Recent Advances: The tremendous progress in methods/technologies and animal modeling has allowed the clarification of phospholipase D (PLD) critical roles in multiple cellular processes, whether directly or indirectly via phosphatidic acid, the lipid product mediating signaling functions. In view of its multiple features and implications in various diseases, PLD has emerged as a drug target. Critical Issues: Although insulin stimulates PLD activity and, in turn, PLD regulates insulin signaling, the impact of the two important PLD isoforms on the metabolic syndrome components remains vague. Therefore, after outlining PLD1/PLD2 characteristics and functions, their role in inflammation, OxS, and CMD has been analyzed and critically reported in the present exhaustive review. The influence of functional foods and nutrients in the regulation of PLD has also been examined. Future Directions: Available evidence supports the implication of PLD in CMD, but only few studies emphasize its mechanisms of action and specific regulation by nutraceutical compounds. Therefore, additional investigations are first needed to clarify the functional role of nutraceutics and, second, to elucidate whether targeting PLDs with food compounds represents an appropriate therapeutic strategy to treat CMD. Antioxid. Redox Signal. 34, 252-278.
Collapse
Affiliation(s)
- Nickolas Auclair
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada.,Department of Pharmacology & Physiology and Université de Montréal, Montreal, Quebec, Canada
| | - Alain T Sané
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada
| | - Edgard Delvin
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada
| | - Schohraya Spahis
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada.,Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada
| | - Emile Levy
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada.,Department of Pharmacology & Physiology and Université de Montréal, Montreal, Quebec, Canada.,Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada
| |
Collapse
|
14
|
Tanaka T, Nakano T, Hozumi Y, Martelli AM, Goto K. Regulation of p53 and NF-κB transactivation activities by DGKζ in catalytic activity-dependent and -independent manners. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:118953. [PMID: 33450306 DOI: 10.1016/j.bbamcr.2021.118953] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 12/15/2020] [Accepted: 01/02/2021] [Indexed: 01/03/2023]
Abstract
Diacylglycerol kinase (DGK) constitutes a family of enzymes that phosphorylate diacylglycerol to phosphatidic acid (PA). These lipids serve as second messengers, thereby activating distinct downstream cascades and different cellular responses. Therefore, DG-to-PA conversion activity induces a phase transition of signaling pathways. One member of the family, DGKζ, is involved closely with stress responses. Morphological data showing that DGKζ localizes predominantly to the nucleus and that it shuttles between the nucleus and the cytoplasm implicate DGKζ in the regulation of transcription factors during stress responses. Tumor suppressor p53 and NF-κB are major stress-responsive transcription factors. They exert opposing effects on cellular pathophysiology. Herein, we summarize DGKζ catalytic activity-dependent and -independent regulatory mechanisms of p53 and NF-κB transactivation activities, including p53 degradation and NF-κB nuclear translocation. We also discuss how each component of DGKζ-interacting protein complex modulates the specificity and selectivity of target gene expression.
Collapse
Affiliation(s)
- Toshiaki Tanaka
- 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
| | - Yasukazu Hozumi
- Department of Cell Biology and Morphology, Akita University Graduate School of Medicine, Akita 010-8543, Japan
| | - Alberto M Martelli
- Department of Biomedical and Neuromotor Sciences, University of Bologna, via Irnerio 48, 40126 Bologna, Italy
| | - Kaoru Goto
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan.
| |
Collapse
|
15
|
Takao S, Akiyama R, Sakane F. Combined inhibition/silencing of diacylglycerol kinase α and ζ simultaneously and synergistically enhances interleukin-2 production in T cells and induces cell death of melanoma cells. J Cell Biochem 2021; 122:494-506. [PMID: 33399248 DOI: 10.1002/jcb.29876] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 11/13/2020] [Accepted: 11/18/2020] [Indexed: 12/16/2022]
Abstract
The α-isozyme of diacylglycerol kinase (DGK) enhances cancer cell proliferation and, conversely, it promotes the nonresponsive immune state known as T-cell anergy. Moreover, a DGKα-selective inhibitor, CU-3, induced cell death in cancer-derived cells and simultaneously enhanced T-cell interleukin-2 production. In addition to DGKα, DGKζ is also known to induce T-cell anergy. In the present study, we examined whether combined inhibition/silencing of DGKα and DGKζ synergistically enhanced T-cell activity. Combined treatment with CU-3 or DGKα-small interfering RNA (siRNA) and DGKζ-siRNA more potently enhanced T-cell receptor-crosslink-dependent interleukin-2 production in Jurkat T cells than treatment with either alone. Intriguingly, in addition to activating T cells, dual inhibition/silencing of DGKα and DGKζ synergistically reduced viability and increased caspase 3/7 activity in AKI melanoma cells. Taken together, these results indicate that combined inhibition/silencing of DGKα and DGKζ simultaneously and synergistically enhances interleukin-2 production in T cells and induces cell death in melanoma. Therefore, dual inhibition/silencing of these DGK isozymes represents an ideal therapy that potently attenuates cancer cell proliferation and simultaneously enhances immune responses that impact anticancer immunity.
Collapse
Affiliation(s)
- Saki Takao
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Rino Akiyama
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| |
Collapse
|
16
|
New Era of Diacylglycerol Kinase, Phosphatidic Acid and Phosphatidic Acid-Binding Protein. Int J Mol Sci 2020; 21:ijms21186794. [PMID: 32947951 PMCID: PMC7555651 DOI: 10.3390/ijms21186794] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [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: 09/14/2020] [Indexed: 12/12/2022] Open
Abstract
Diacylglycerol kinase (DGK) phosphorylates diacylglycerol (DG) to generate phosphatidic acid (PA). Mammalian DGK consists of ten isozymes (α–κ) and governs a wide range of physiological and pathological events, including immune responses, neuronal networking, bipolar disorder, obsessive-compulsive disorder, fragile X syndrome, cancer, and type 2 diabetes. DG and PA comprise diverse molecular species that have different acyl chains at the sn-1 and sn-2 positions. Because the DGK activity is essential for phosphatidylinositol turnover, which exclusively produces 1-stearoyl-2-arachidonoyl-DG, it has been generally thought that all DGK isozymes utilize the DG species derived from the turnover. However, it was recently revealed that DGK isozymes, except for DGKε, phosphorylate diverse DG species, which are not derived from phosphatidylinositol turnover. In addition, various PA-binding proteins (PABPs), which have different selectivities for PA species, were recently found. These results suggest that DGK–PA–PABP axes can potentially construct a large and complex signaling network and play physiologically and pathologically important roles in addition to DGK-dependent attenuation of DG–DG-binding protein axes. For example, 1-stearoyl-2-docosahexaenoyl-PA produced by DGKδ interacts with and activates Praja-1, the E3 ubiquitin ligase acting on the serotonin transporter, which is a target of drugs for obsessive-compulsive and major depressive disorders, in the brain. This article reviews recent research progress on PA species produced by DGK isozymes, the selective binding of PABPs to PA species and a phosphatidylinositol turnover-independent DG supply pathway.
Collapse
|
17
|
Polyunsaturated fatty acid-containing phosphatidic acids selectively interact with L-lactate dehydrogenase A and induce its secondary structural change and inactivation. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158768. [PMID: 32717303 DOI: 10.1016/j.bbalip.2020.158768] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 06/17/2020] [Accepted: 07/19/2020] [Indexed: 12/18/2022]
Abstract
Phosphatidic acid (PA) consists of various molecular species that have different fatty acyl chains at the sn-1 and sn-2 positions; and consequently, mammalian cells contain at least 50 structurally distinct PA molecular species. However, the different roles of each PA species are poorly understood. In the present study, we attempted to identify dipalmitoyl (16:0/16:0)-PA-binding proteins from mouse skeletal muscle using liposome precipitation and tandem mass spectrometry analysis. We identified L-lactate dehydrogenase (LDH) A, which catalyzes conversion of pyruvate to lactate and is a key checkpoint of anaerobic glycolysis critical for tumor growth, as a 16:0/16:0-PA-binding protein. LDHA did not substantially associate with other phospholipids, such as phosphatidylcholine, phosphatidylserine, phosphatidylglycerol, phosphatidylinositol, phosphoinositides and cardiolipin at physiological pH (7.4), indicating that LDHA specifically bound to PA. Interestingly, 18:0/18:0-, 18:0/20:4- and 18:0/22:6-PA also interacted with LDHA, and their binding activities were stronger than 16:0/16:0-PA at pH 7.4. Moreover, circular dichroism spectrometry showed that 18:0/20:4- and 18:0/22:6-PA, but not 16:0/16:0- or 18:0/18:0-PA, significantly reduced the α-helical structure of LDHA. Furthermore, 18:0/20:4- and 18:0/22:6-PA attenuated LDH activity. Taken together, we demonstrated for the first time that LDHA is a PA-binding protein and is a unique PA-binding protein that is structurally and functionally controlled by associating with 18:0/20:4- and 18:0/22:6-PA.
Collapse
|
18
|
Murakami C, Hoshino F, Sakai H, Hayashi Y, Yamashita A, Sakane F. Diacylglycerol kinase δ and sphingomyelin synthase-related protein functionally interact via their sterile α motif domains. J Biol Chem 2020; 295:2932-2947. [PMID: 31980461 DOI: 10.1074/jbc.ra119.012369] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/23/2020] [Indexed: 12/27/2022] Open
Abstract
The δ isozyme of diacylglycerol kinase (DGKδ) plays critical roles in lipid signaling by converting diacylglycerol (DG) to phosphatidic acid (PA). We previously demonstrated that DGKδ preferably phosphorylates palmitic acid (16:0)- and/or palmitoleic acid (16:1)-containing DG molecular species, but not arachidonic acid (20:4)-containing DG species, which are recognized as DGK substrates derived from phosphatidylinositol turnover, in high glucose-stimulated myoblasts. However, little is known about the origin of these DG molecular species. DGKδ and two DG-generating enzymes, sphingomyelin synthase (SMS) 1 and SMS-related protein (SMSr), contain a sterile α motif domain (SAMD). In this study, we found that SMSr-SAMD, but not SMS1-SAMD, co-immunoprecipitates with DGKδ-SAMD. Full-length DGKδ co-precipitated with full-length SMSr more strongly than with SMS1. However, SAMD-deleted variants of SMSr and DGKδ interacted only weakly with full-length DGKδ and SMSr, respectively. These results strongly suggested that DGKδ interacts with SMSr through their respective SAMDs. To determine the functional outcomes of the relationship between DGKδ and SMSr, we used LC-MS/MS to investigate whether overexpression of DGKδ and/or SMSr in COS-7 cells alters the levels of PA species. We found that SMSr overexpression significantly enhances the production of 16:0- or 16:1-containing PA species such as 14:0/16:0-, 16:0/16:0-, 16:0/18:1-, and/or 16:1/18:1-PA in DGKδ-overexpressing COS-7 cells. Moreover, SMSr enhanced DGKδ activity via their SAMDs in vitro Taken together, these results strongly suggest that SMSr is a candidate DG-providing enzyme upstream of DGKδ and that the two enzymes represent a new pathway independent of phosphatidylinositol turnover.
Collapse
Affiliation(s)
- Chiaki Murakami
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan
| | - Fumi Hoshino
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan
| | - 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
| | - Yasuhiro Hayashi
- Faculty of Pharma Sciences, Teikyo University, Kaga 2-11-1, Itabashi-ku, Tokyo 173-8605, Japan
| | - Atsushi Yamashita
- Faculty of Pharma Sciences, Teikyo University, Kaga 2-11-1, Itabashi-ku, Tokyo 173-8605, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan.
| |
Collapse
|
19
|
Nakano T, Ogasawara S, Tanaka T, Hozumi Y, Sano M, Sayama Y, Yamada S, Kaneko MK, Kato Y, Goto K. DzMab-1: Anti-Human Diacylglycerol Kinaseζ Monoclonal Antibody for Immunocytochemistry. Monoclon Antib Immunodiagn Immunother 2019; 38:179-182. [DOI: 10.1089/mab.2019.0024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University Faculty of Medicine, Yamagata, Japan
| | - Satoshi Ogasawara
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, 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
| | - Masato Sano
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yusuke Sayama
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Shinji Yamada
- 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
- New Industry Creation Hatchery Center, Tohoku University, Sendai, Japan
| | - Kaoru Goto
- Department of Anatomy and Cell Biology, Yamagata University Faculty of Medicine, Yamagata, Japan
| |
Collapse
|
20
|
Komenoi S, Suzuki Y, Asami M, Murakami C, Hoshino F, Chiba S, Takahashi D, Kado S, Sakane F. Microarray analysis of gene expression in the diacylglycerol kinase η knockout mouse brain. Biochem Biophys Rep 2019; 19:100660. [PMID: 31297456 PMCID: PMC6597918 DOI: 10.1016/j.bbrep.2019.100660] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 06/17/2019] [Accepted: 06/19/2019] [Indexed: 12/18/2022] Open
Abstract
We have revealed that diacylglycerol kinase η (DGKη)-knockout (KO) mice display bipolar disorder (BPD) remedy-sensitive mania-like behaviors. However, the molecular mechanisms causing the mania-like abnormal behaviors remain unclear. In the present study, microarray analysis was performed to determine global changes in gene expression in the DGKη-KO mouse brain. We found that the DGKη-KO brain had 43 differentially expressed genes and the following five affected biological pathways: "neuroactive ligand-receptor interaction", "transcription by RNA polymerase II", "cytosolic calcium ion concentration", "Jak-STAT signaling pathway" and "ERK1/2 cascade". Interestingly, mRNA levels of prolactin and growth hormone, which are augmented in BPD patients and model animals, were most strongly increased. Notably, all five biological pathways include at least one gene among prolactin, growth hormone, forkhead box P3, glucagon-like peptide 1 receptor and interleukin 1β, which were previously implicated in BPD. Consistent with the microarray data, phosphorylated ERK1/2 levels were decreased in the DGKη-KO brain. Microarray analysis showed that the expression levels of several glycerolipid metabolism-related genes were also changed. Liquid chromatography-mass spectrometry revealed that several polyunsaturated fatty acid (PUFA)-containing phosphatidic acid (PA) molecular species were significantly decreased as a result of DGKη deficiency, suggesting that the decrease affects PUFA metabolism. Intriguingly, the PUFA-containing lysoPA species were markedly decreased in DGKη-KO mouse blood. Taken together, our study provides not only key broad knowledge to gain novel insights into the underlying mechanisms for the mania-like behaviors but also information for developing BPD diagnostics.
Collapse
Key Words
- BPD, bipolar disorder
- Bipolar disorder
- DAVID, Database for AnnotationVisualization and Integrated Discovery
- DG, diacylglycerol
- DGK, diacylglycerol kinase
- Diacylglycerol kinase
- ERK, extracellular signal-regulated kinase
- Fpr2, N-formyl peptide receptor 2
- GO:BP, Gene Ontology: Biological Process
- GWAS, genome-wide association study
- Gh, growth hormone
- Glp1r, glucagon-like peptide 1 receptor
- Growth hormone
- Il1b, interleukin 1β
- KEGG, Kyoto Encyclopedia of Genes and Genomes
- KO, knockout
- LC-MS, liquid chromatography-mass spectrometry
- LPA, lysophosphatidic acid
- Lysophosphatidic acid
- MEK, mitogen-activated protein kinase/ERK kinase
- PA, phosphatidic acid
- PI, phosphatidylinositol
- PUFA, polyunsaturated fatty acid
- Phosphatidic acid
- Prl, prolactin
- Prolactin
- SERT, serotonin transporter
- WT, wild type
Collapse
Affiliation(s)
- Suguru Komenoi
- Department of Chemistry, Graduate School of Science, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Yuji Suzuki
- Department of Chemistry, Graduate School of Science, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Maho Asami
- Department of Chemistry, Graduate School of Science, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Chiaki Murakami
- Department of Chemistry, Graduate School of Science, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Fumi Hoshino
- Department of Chemistry, Graduate School of Science, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Sohei Chiba
- Department of Chemistry, Graduate School of Science, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Daisuke Takahashi
- Department of Chemistry, Graduate School of Science, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Sayaka Kado
- Center for Analytical Instrumentation, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
- Corresponding author. Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan.
| |
Collapse
|
21
|
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.
Collapse
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
| |
Collapse
|
22
|
Nakano T, Ogasawara S, Tanaka T, Hozumi Y, Yamaki A, Sakane F, Shirai Y, Nakamura T, Yanaka M, Yamada S, Kaneko MK, Kato Y, Goto K. DgMab-6: Antihuman DGKγ Monoclonal Antibody for Immunocytochemistry. Monoclon Antib Immunodiagn Immunother 2018; 37:229-232. [DOI: 10.1089/mab.2018.0026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University Faculty of Medicine, Yamagata, Japan
| | - Satoshi Ogasawara
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, 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
| | - Atsumi Yamaki
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Yasuhito Shirai
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Japan
| | - Takuro Nakamura
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Miyuki Yanaka
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Shinji Yamada
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Mika K. Kaneko
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Yukinari Kato
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
- New Industry Creation Hatchery Center, Tohoku University, Sendai, Miyagi, Japan
| | - Kaoru Goto
- Department of Anatomy and Cell Biology, Yamagata University Faculty of Medicine, Yamagata, Japan
| |
Collapse
|
23
|
Sakane F, Mizuno S, Takahashi D, Sakai H. Where do substrates of diacylglycerol kinases come from? Diacylglycerol kinases utilize diacylglycerol species supplied from phosphatidylinositol turnover-independent pathways. Adv Biol Regul 2018; 67:101-108. [PMID: 28918129 DOI: 10.1016/j.jbior.2017.09.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 09/08/2017] [Accepted: 09/08/2017] [Indexed: 06/07/2023]
Abstract
Diacylglycerol kinase (DGK) phosphorylates diacylglycerol (DG) to produce phosphatidic acid (PA). Mammalian DGK comprises ten isozymes (α-κ) and regulates a wide variety of physiological and pathological events, such as cancer, type II diabetes, neuronal disorders and immune responses. DG and PA consist of various molecular species that have different acyl chains at the sn-1 and sn-2 positions, and consequently, mammalian cells contain at least 50 structurally distinct DG/PA species. Because DGK is one of the components of phosphatidylinositol (PI) turnover, the generally accepted dogma is that all DGK isozymes utilize 18:0/20:4-DG derived from PI turnover. We recently established a specific liquid chromatography-mass spectrometry method to analyze which PA species were generated by DGK isozymes in a cell stimulation-dependent manner. Interestingly, we determined that DGKδ, which is closely related to the pathogenesis of type II diabetes, preferentially utilized 14:0/16:0-, 14:0/16:1-, 16:0/16:0-, 16:0/16:1-, 16:0/18:0- and 16:0/18:1-DG species (X:Y = the total number of carbon atoms: the total number of double bonds) supplied from the phosphatidylcholine-specific phospholipase C pathway, but not 18:0/20:4-DG, in high glucose-stimulated C2C12 myoblasts. Moreover, DGKα mainly consumed 14:0/16:0-, 16:0/18:1-, 18:0/18:1- and 18:1/18:1-DG species during cell proliferation in AKI melanoma cells. Furthermore, we found that 16:0/16:0-PA was specifically produced by DGKζ in Neuro-2a cells during retinoic acid- and serum starvation-induced neuronal differentiation. These results indicate that DGK isozymes utilize a variety of DG molecular species derived from PI turnover-independent pathways as substrates in different stimuli and cells. DGK isozymes phosphorylate various DG species to generate various PA species. It was revealed that the modes of activation of conventional and novel protein kinase isoforms by DG molecular species varied considerably. However, PA species-selective binding proteins have not been found to date. Therefore, we next attempted to identify PA species-selective binding proteins from the mouse brain and identified α-synuclein, which has causal links to Parkinson's disease. Intriguingly, we determined that among phospholipids, including several PA species (16:0/16:0-PA, 16:0/18:1-PA, 18:1/18:1-PA, 18:0/18:0-PA and 18:0/20:4-PA); 18:1/18:1-PA was the most strongly bound PA to α-synuclein. Moreover, 18:1/18:1-PA strongly enhanced secondary structural changes from the random coil form to the α-helix form and generated a multimeric and proteinase K-resistant α-synuclein protein. In contrast with the dogma described above, our recent studies strongly suggest that PI turnover-derived DG species and also various DG species derived from PI turnover-independent pathways are utilized by DGK isozymes. DG species supplied from distinct pathways may be utilized by DGK isozymes based on different stimuli present in different types of cells, and individual PA molecular species would have specific targets and exert their own physiological functions.
Collapse
Affiliation(s)
- Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan.
| | - Satoru Mizuno
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Daisuke Takahashi
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Hiromichi Sakai
- Department of Biosignaling and Radioisotope Experiment, Interdisciplinary Center for Science Research, Organization for Research and Academic Information, Shimane University, Izumo, Japan
| |
Collapse
|
24
|
Takato T, Iwata K, Murakami C, Wada Y, Sakane F. Chronic administration of myristic acid improves hyperglycaemia in the Nagoya-Shibata-Yasuda mouse model of congenital type 2 diabetes. Diabetologia 2017; 60:2076-2083. [PMID: 28707095 DOI: 10.1007/s00125-017-4366-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 06/06/2017] [Indexed: 12/18/2022]
Abstract
AIMS/HYPOTHESIS Previously, we demonstrated that myristic acid (14:0) increases levels of diacylglycerol kinase (DGK) δ, a key enzyme involved in type 2 diabetes exacerbation, and enhances glucose uptake in C2C12 myotube cells. Moreover, results from a population-based cohort study suggest that consumption of high-fat dairy products, which contain high amounts of myristic acid, is associated with a lower risk of developing type 2 diabetes. Taken together, we hypothesised that intake of myristic acid reduces type 2 diabetes risk in vivo. The aim of this study was to examine the glucose-lowering effect of myristic acid in Nagoya-Shibata-Yasuda (NSY) mice, a spontaneous model for studying obesity-related type 2 diabetes. METHODS Male NSY mice were orally administered vehicle (n = 9), 300 mg/kg of myristic acid (n = 14) or 300 mg/kg of palmitic acid (16:0) (n = 9) every other day from 4 weeks of age. Glucose and insulin tolerance tests were performed at weeks 18, 24 and 30, and weeks 20 and 26, respectively. DGKδ levels were measured in skeletal muscle from 32-36-week-old NSY mice via western blot. RESULTS Chronic oral administration of myristic acid ameliorated glucose tolerance (24-28% decrease in blood glucose levels during glucose tolerance tests) and reduced insulin-responsive blood glucose levels (~20% decrease) in male NSY mice compared with vehicle and palmitic acid groups at 24-30 weeks of age (the age at which the severity of type 2 diabetes is exacerbated in NSY mice). Myristic acid also attenuated the increase in body weight seen in NSY mice. Furthermore, the fatty acid increased DGKδ levels (~1.6-fold) in skeletal muscle of NSY mice. CONCLUSIONS/INTERPRETATION These results suggest that the chronic oral administration of myristic acid improves hyperglycaemia by decreasing insulin-responsive glucose levels and reducing body weight, and that the fatty acid accounts for the diabetes protective properties of high-fat dairy products. Myristic acid is a potential candidate for the prevention and treatment of type 2 diabetes mellitus and its related diseases.
Collapse
Affiliation(s)
- Tamae Takato
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Kai Iwata
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Chiaki Murakami
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Yuko Wada
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan.
| |
Collapse
|
25
|
Murakami E, Shionoya T, Komenoi S, Suzuki Y, Sakane F. Cloning and Characterization of Novel Testis-Specific Diacylglycerol Kinase η Splice Variants 3 and 4. PLoS One 2016; 11:e0162997. [PMID: 27643686 PMCID: PMC5028035 DOI: 10.1371/journal.pone.0162997] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 08/31/2016] [Indexed: 01/04/2023] Open
Abstract
Diacylglycerol kinase (DGK) phosphorylates DG to generate phosphatidic acid. Recently, we found that a new alternative splicing product of the DGKη gene, DGKη3, which lacks exon 26 encoding 31 amino acid residues, was expressed only in the secondary spermatocytes and round spermatids of the testis. In this study, we cloned the full length DGKη3 gene and confirmed the endogenous expression of its protein product. During the cloning procedure, we found a new testis-specific alternative splicing product of the DGKη gene, DGKη4, which lacks half of the catalytic domain. We examined the DGK activity and subcellular localization of DGKη3 and η4. DGKη3 had almost the same activity as DGKη1, whereas the activity of DGKη4 was not detectable. In resting NEC8 cells (human testicular germ cell tumor cell line), DGKη1, η3 and η4 were broadly distributed in the cytoplasm. When osmotically shocked, DGKη1 and η4 were distributed in punctate vesicles in the cytoplasm. In contrast, DGKη3 was partly translocated to the plasma membrane and co-localized with the actin cytoskeleton. These results suggest that DGKη3 and η4 have properties different from those of DGKη1 and that they play roles in the testis in a different manner.
Collapse
Affiliation(s)
- Eri Murakami
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Takao Shionoya
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Suguru Komenoi
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Yuji Suzuki
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
- * E-mail:
| |
Collapse
|
26
|
Sakane F, Mizuno S, Komenoi S. Diacylglycerol Kinases as Emerging Potential Drug Targets for a Variety of Diseases: An Update. Front Cell Dev Biol 2016; 4:82. [PMID: 27583247 PMCID: PMC4987324 DOI: 10.3389/fcell.2016.00082] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 07/29/2016] [Indexed: 01/08/2023] Open
Abstract
Ten mammalian diacylglycerol kinase (DGK) isozymes (α–κ) have been identified to date. Our previous review noted that several DGK isozymes can serve as potential drug targets for cancer, epilepsy, autoimmunity, cardiac hypertrophy, hypertension and type II diabetes (Sakane et al., 2008). Since then, recent genome-wide association studies have implied several new possible relationships between DGK isozymes and diseases. For example, DGKθ and DGKκ have been suggested to be associated with susceptibility to Parkinson's disease and hypospadias, respectively. In addition, the DGKη gene has been repeatedly identified as a bipolar disorder (BPD) susceptibility gene. Intriguingly, we found that DGKη-knockout mice showed lithium (BPD remedy)-sensitive mania-like behaviors, suggesting that DGKη is one of key enzymes of the etiology of BPD. Because DGKs are potential drug targets for a wide variety of diseases, the development of DGK isozyme-specific inhibitors/activators has been eagerly awaited. Recently, we have identified DGKα-selective inhibitors. Because DGKα has both pro-tumoral and anti-immunogenic properties, the DGKα-selective inhibitors would simultaneously have anti-tumoral and pro-immunogenic (anti-tumor immunogenic) effects. Although the ten DGK isozymes are highly similar to each other, our current results have encouraged us to identify and develop specific inhibitors/activators against every DGK isozyme that can be effective regulators and drugs against a wide variety of physiological events and diseases.
Collapse
Affiliation(s)
- Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University Chiba, Japan
| | - Satoru Mizuno
- Department of Chemistry, Graduate School of Science, Chiba University Chiba, Japan
| | - Suguru Komenoi
- Department of Chemistry, Graduate School of Science, Chiba University Chiba, Japan
| |
Collapse
|
27
|
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.
Collapse
|
28
|
Wada Y, Sakiyama S, Sakai H, Sakane F. Myristic Acid Enhances Diacylglycerol Kinase δ-Dependent Glucose Uptake in Myotubes. Lipids 2016; 51:897-903. [PMID: 27206979 DOI: 10.1007/s11745-016-4162-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 05/05/2016] [Indexed: 11/28/2022]
Abstract
Decreased expression of diacylglycerol kinase (DGK) δ in skeletal muscles attenuates glucose uptake and is closely related to the pathogenesis of type 2 diabetes. Therefore, up-regulation of DGKδ expression is thought to protect and improve glucose homoeostasis in type 2 diabetes. We recently determined that myristic acid (14:0), but not palmitic (16:0) or stearic (18:0) acid, significantly increased DGKδ2 protein expression in mouse C2C12 myotubes. In the current study, we analyzed whether myristic acid indeed enhances glucose uptake in C2C12 myotubes. We observed that myristic acid caused ~1.4-fold increase in insulin-independent glucose uptake. However, palmitic and stearic acids failed to enhance glucose uptake. DGKδ-specific siRNA decreased myristic acid-dependent increase of glucose uptake. Moreover, overexpression of DGKδ2 enhanced glucose uptake in C2C12 cells in the absence of myristic acid treatment. Taken together, these results strongly suggest that myristic acid enhances basal glucose uptake in myotubes in a DGKδ2 expression-dependent manner.
Collapse
Affiliation(s)
- Yuko Wada
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Shizuka Sakiyama
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Hiromichi Sakai
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan.
| |
Collapse
|
29
|
Kume A, Kawase K, Komenoi S, Usuki T, Takeshita E, Sakai H, Sakane F. The Pleckstrin Homology Domain of Diacylglycerol Kinase η Strongly and Selectively Binds to Phosphatidylinositol 4,5-Bisphosphate. J Biol Chem 2016; 291:8150-61. [PMID: 26887948 DOI: 10.1074/jbc.m115.648717] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Indexed: 11/06/2022] Open
Abstract
Type II diacylglycerol kinase (DGK) isozymes (δ, η, and κ) have a pleckstrin homology domain (PH) at their N termini. Here, we investigated the lipid binding properties of the PHs of type II DGK isozymes using protein-lipid overlay and liposome binding assays. The PH of DGKη showed the most pronounced binding activity to phosphatidylinositol (PI) 4,5-bisphosphate (PI(4,5)P2) among the various glycero- and sphingolipids including PI 3,4,5-trisphosphate, PI 3,4-bisphosphate, PI 3-phosphate, PI 4-phosphate, and PI 5-phosphate. Moreover, the PI(4,5)P2binding activity of the DGKη-PH was significantly stronger than that of other type II DGK isozymes. Notably, compared with the PH of phospholipase C (PLC) δ1, which is generally utilized as a cellular PI(4,5)P2- probe, the DGKη-PH is equal to or superior than the PLCδ1-PH in terms of affinity and selectivity for PI(4,5)P2 Furthermore, in COS-7 cells, GFP-fused wild-type DGKη1 and its PH partly translocated from the cytoplasm to the plasma membrane where the PLCδ1-PH was co-localized in response to hyperosmotic stress in an inositol 5-phosphatase-sensitive manner, whereas a PH deletion mutant did not. Moreover, K74A and R85A mutants of DGKη-PH, which lack the conserved basic amino acids thought to ligate PI(4,5)P2, were indeed unable to bind to PI(4,5)P2and co-localize with the PLCδ1-PH even in osmotically shocked cells. Overexpression of wild-type DGKη1 enhanced EGF-dependent phosphorylation of ERK, whereas either K74A or R85A mutant did not. Taken together, these results indicate that the DGKη-PH preferentially interacts with PI(4,5)P2and has crucial roles in regulating the subcellular localization and physiological function of DGKη. Moreover, the DGKη-PH could serve as an excellent cellular sensor for PI(4,5)P2.
Collapse
Affiliation(s)
- Aiko Kume
- From the Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Koki Kawase
- From the Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Suguru Komenoi
- From the Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Takako Usuki
- From the Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Ena Takeshita
- From the Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Hiromichi Sakai
- From the Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Fumio Sakane
- From the Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| |
Collapse
|
30
|
Liu K, Kunii N, Sakuma M, Yamaki A, Mizuno S, Sato M, Sakai H, Kado S, Kumagai K, Kojima H, Okabe T, Nagano T, Shirai Y, Sakane F. A novel diacylglycerol kinase α-selective inhibitor, CU-3, induces cancer cell apoptosis and enhances immune response. J Lipid Res 2016; 57:368-79. [PMID: 26768655 DOI: 10.1194/jlr.m062794] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Indexed: 02/02/2023] Open
Abstract
Diacylglycerol kinase (DGK) consists of 10 isozymes. The α-isozyme enhances the proliferation of cancer cells. However, DGKα facilitates the nonresponsive state of immunity known as T-cell anergy; therefore, DGKα enhances malignant traits and suppresses immune surveillance. The aim of this study was to identify a novel small molecule that selectively and potently inhibits DGKα activity. We screened a library containing 9,600 chemical compounds using a newly established high-throughput DGK assay. As a result, we have obtained a promising compound, 5-[(2E)-3-(2-furyl)prop-2-enylidene]-3-[(phenylsulfonyl)amino]2-thioxo-1,3-thiazolidin-4-one) (CU-3), which selectively inhibited DGKα with an IC50 value of 0.6 μM. CU-3 targeted the catalytic region, but not the regulatory region, of DGKα. CU-3 competitively reduced the affinity of DGKα for ATP, but not diacylglycerol or phosphatidylserine. Moreover, this compound induced apoptosis in HepG2 hepatocellular carcinoma and HeLa cervical cancer cells while simultaneously enhancing the interleukin-2 production of Jurkat T cells. Taken together, these results indicate that CU-3 is a selective and potent inhibitor for DGKα and can be an ideal anticancer drug candidate that attenuates cancer cell proliferation and simultaneously enhances immune responses including anticancer immunity.
Collapse
Affiliation(s)
- Ke Liu
- Department of Chemistry, Chiba University, Chiba 263-8522, Japan
| | - Naoko Kunii
- Department of Chemistry, Chiba University, Chiba 263-8522, Japan
| | - Megumi Sakuma
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Atsumi Yamaki
- Department of Chemistry, Chiba University, Chiba 263-8522, Japan
| | - Satoru Mizuno
- Department of Chemistry, Chiba University, Chiba 263-8522, Japan
| | - Mayu Sato
- Department of Chemistry, Chiba University, Chiba 263-8522, Japan
| | - Hiromichi Sakai
- Department of Chemistry, Chiba University, Chiba 263-8522, Japan
| | - Sayaka Kado
- Graduate School of Science and Center for Analytical Instrumentation, Chiba University, Chiba 263-8522, Japan
| | - Kazuo Kumagai
- Drug Discovery Initiative, University of Tokyo, Tokyo 113-0033, Japan
| | - Hirotatsu Kojima
- Drug Discovery Initiative, University of Tokyo, Tokyo 113-0033, Japan
| | - Takayoshi Okabe
- Drug Discovery Initiative, University of Tokyo, Tokyo 113-0033, Japan
| | - Tetsuo Nagano
- Drug Discovery Initiative, University of Tokyo, Tokyo 113-0033, Japan
| | - Yasuhito Shirai
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Fumio Sakane
- Department of Chemistry, Chiba University, Chiba 263-8522, Japan
| |
Collapse
|
31
|
Tanaka T, Tsuchiya R, Hozumi Y, Nakano T, Okada M, Goto K. Reciprocal regulation of p53 and NF-κB by diacylglycerol kinase ζ. Adv Biol Regul 2015; 60:15-21. [PMID: 26521214 DOI: 10.1016/j.jbior.2015.09.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 09/30/2015] [Accepted: 09/30/2015] [Indexed: 11/29/2022]
Abstract
Diacylglycerol kinase (DGK) participates in lipid mediated-signal transduction. It phosphorylates diacylglycerol (DG) to phosphatidic acid (PA), thereby regulating the balanced control of these second messenger actions. Previous reports have described that one DGK family, DGKζ, is closely involved in stress responses under various conditions. Cellular stress response, a physiological process enabling cells to cope with an altered environment, is finely tuned through various signaling cascades and their molecular crosstalk. The major components of stress response are p53 and NF-κB. p53 generally serves as a proapoptotic transcriptional factor, whereas NF-κB promotes resistance to programmed cell death under most circumstances. Recent studies have suggested that DGKζ facilitates p53 degradation in cytoplasm through ubiquitin proteasome system and that DGKζ deletion upregulates p53 protein levels under basal and DNA-damage conditions. Counter-intuitively, however, DGKζ deletion suppresses p53 transcriptional activity despite increased p53 levels. In contrast, DGKζ knockdown engenders enhancement of NF-κB pathway in response to cytokines such as TNF-α and IL-1β. In response to these cytokines, DGKζ downregulation accelerates phosphorylation of the p65 subunit and its nuclear translocation, thereby enhancing NF-κB transcriptional activity. Furthermore, DGKζ deficiency is shown to promote increased association of p65 subunit with the transcriptional cofactor CBP. It is particularly interesting that this association is observed even under basal conditions in the absence of stimulation. These findings suggest that DGKζ plays a role in sequestration of the limiting pool of CBP/p300 between the NF-κB p65 subunit and p53, and that DGKζ downregulation shifts CBP/p300 toward the NF-κB subunit to regulate reciprocally antagonistic phenotypes of these transcription factors.
Collapse
Affiliation(s)
- Toshiaki Tanaka
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-Nishi 2-2-2, Yamagata 990-9585, Japan.
| | - Rieko Tsuchiya
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-Nishi 2-2-2, Yamagata 990-9585, Japan
| | - Yasukazu Hozumi
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-Nishi 2-2-2, Yamagata 990-9585, Japan
| | - Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-Nishi 2-2-2, Yamagata 990-9585, Japan
| | - Masashi Okada
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-Nishi 2-2-2, Yamagata 990-9585, Japan
| | - Kaoru Goto
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-Nishi 2-2-2, Yamagata 990-9585, Japan.
| |
Collapse
|
32
|
Komenoi S, Takemura F, Sakai H, Sakane F. Diacylglycerol kinase η1 is a high affinity isozyme for diacylglycerol. FEBS Lett 2015; 589:1272-7. [DOI: 10.1016/j.febslet.2015.03.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 03/26/2015] [Accepted: 03/27/2015] [Indexed: 12/13/2022]
|
33
|
Sakai H, Kado S, Taketomi A, Sakane F. Diacylglycerol kinase δ phosphorylates phosphatidylcholine-specific phospholipase C-dependent, palmitic acid-containing diacylglycerol species in response to high glucose levels. J Biol Chem 2014; 289:26607-26617. [PMID: 25112873 DOI: 10.1074/jbc.m114.590950] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Decreased expression of diacylglycerol (DG) kinase (DGK) δ in skeletal muscles is closely related to the pathogenesis of type 2 diabetes. To identify DG species that are phosphorylated by DGKδ in response to high glucose stimulation, we investigated high glucose-dependent changes in phosphatidic acid (PA) molecular species in mouse C2C12 myoblasts using a newly established liquid chromatography/MS method. We found that the suppression of DGKδ2 expression by DGKδ-specific siRNAs significantly inhibited glucose-dependent increases in 30:0-, 32:0-, and 34:0-PA and moderately attenuated 30:1-, 32:1-, and 34:1-PA. Moreover, overexpression of DGKδ2 also enhanced the production of these PA species. MS/MS analysis revealed that these PA species commonly contain palmitic acid (16:0). D609, an inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC), significantly inhibited the glucose-stimulated production of the palmitic acid-containing PA species. Moreover, PC-PLC was co-immunoprecipitated with DGKδ2. These results strongly suggest that DGKδ preferably metabolizes palmitic acid-containing DG species supplied from the PC-PLC pathway, but not arachidonic acid (20:4)-containing DG species derived from the phosphatidylinositol turnover, in response to high glucose levels.
Collapse
Affiliation(s)
- Hiromichi Sakai
- Department of Chemistry, Graduate School of Science and Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522
| | - Sayaka Kado
- Center for Analytical Instrumentation, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 and
| | - Akinobu Taketomi
- Department of General Surgery, Graduate School of Medicine, Hokkaido University, North 15, West 7, Kita-ku, Sapporo 060-8638, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science and Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522.
| |
Collapse
|
34
|
Matsui H, Hozumi Y, Tanaka T, Okada M, Nakano T, Suzuki Y, Iseki K, Kakehata S, Topham MK, Goto K. Role of the N-terminal hydrophobic residues of DGKε in targeting the endoplasmic reticulum. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1842:1440-50. [PMID: 25048194 DOI: 10.1016/j.bbalip.2014.07.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 06/24/2014] [Accepted: 07/09/2014] [Indexed: 10/25/2022]
Abstract
The endoplasmic reticulum (ER), comprised of an interconnected membrane network, is a site of phospholipid and protein synthesis. The diacylglycerol kinase (DGK) enzyme family catalyzes phosphorylation of diacylglycerol to phosphatidic acid. Both of these lipids are known not only to serve as second messengers but also to represent intermediate precursors of lipids of various kinds. The DGK family is targeted to distinct subcellular sites in cDNA-transfected and native cells. Of DGKs, DGKε localizes primarily to the ER, suggesting that this isozyme plays a role in this organelle. Using experiments with various deletion and substitution mutants, this study examined the molecular mechanism of how DGKε is targeted to the ER. Results demonstrate that the N-terminal hydrophobic sequence 20-40 plays a necessary role in targeting of DGKε to the ER. This hydrophobic amino acid segment is predicted to adopt an α-helix structure, in which Leu22, L25, and L29 are present in mutual proximity, forming a hydrophobic patch. When these hydrophobic Leu residues were replaced with hydrophilic amino acid Gln, the mutant fragment designated DGKε (20-40/L22Q,L25Q,L29Q) exhibits diffuse distribution in the cytoplasm. Moreover, full-length DGKε containing these substitutions, DGKε (L22Q,L25Q,L29Q), is shown to distribute diffusely in the cytoplasm. These results indicate that the N-terminal hydrophobic residues play a key role in DGKε targeting to the ER membrane. Functionally, knockdown or deletion of DGKε affects the unfolding protein response pathways, thereby rendering the cells susceptible to apoptosis, to some degree, under ER stress conditions.
Collapse
Affiliation(s)
- Hirooki Matsui
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan; Department of Otolaryngology, Head and Neck Surgery, 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
| | - Toshiaki Tanaka
- 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
| | - Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Yusuke Suzuki
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan; Department of Otolaryngology, Head and Neck Surgery, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Ken Iseki
- Department of Emergency and Critical Care Medicine, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Seiji Kakehata
- Department of Otolaryngology, Head and Neck Surgery, 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
| | - Kaoru Goto
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan.
| |
Collapse
|
35
|
Cellular expression and localization of DGKζ-interacting NAP1-like proteins in the brain and functional implications under hypoxic stress. Histochem Cell Biol 2014; 142:461-71. [DOI: 10.1007/s00418-014-1226-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2014] [Indexed: 11/27/2022]
|
36
|
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.
Collapse
Affiliation(s)
- Shizuka Sakiyama
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | | | | | | |
Collapse
|
37
|
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.
Collapse
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
Collapse
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
| |
Collapse
|
38
|
Takeshita E, Kume A, Maeda Y, Sakai H, Sakane F. Diacylglycerol kinase γ is a novel anionic phospholipid binding protein with a selective binding preference. Biochem Biophys Res Commun 2014; 444:617-21. [PMID: 24486543 DOI: 10.1016/j.bbrc.2014.01.116] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 01/23/2014] [Indexed: 11/30/2022]
Abstract
There are ten isozymes of diacylglycerol kinase (DGK), and they regulate diverse patho-physiological functions. Here, we investigated the lipid-binding properties of DGK isozymes using protein-lipid overlay and liposome-binding assays. DGKγ showed a strong binding activity compared with other DGK isozymes for phosphatidic acid (PA) among the various glycerophospholipids tested. However, DGKγ failed to interact with DG and lyso-PA. Moreover, the isozyme was capable of binding to ceramide-1-phosphate but not to ceramide or sphingosine-1-phosphate. The isozyme bound more strongly to PA containing unsaturated fatty acid than to PA having only saturated fatty acid. An analysis using a series of deletion mutants of DGKγ revealed that the N-terminal region, which contains a recoverin homology domain and EF-hand motifs, is responsible for the PA binding activity of DGKγ. Taken together, these results indicate that DGKγ is an anionic phospholipid binding protein that preferably interacts with a small highly charged head group that is very close to the glycerol or sphingosine backbone.
Collapse
Affiliation(s)
- Ena Takeshita
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Aiko Kume
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Yuki Maeda
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Hiromichi Sakai
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
| |
Collapse
|
39
|
Goto K, Tanaka T, Nakano T, Okada M, Hozumi Y, Topham MK, Martelli AM. DGKζ under stress conditions: “to be nuclear or cytoplasmic, that is the question”. Adv Biol Regul 2014; 54:242-253. [PMID: 24119575 DOI: 10.1016/j.jbior.2013.08.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 08/31/2013] [Indexed: 06/02/2023]
Abstract
Eukaryotic cells have evolved to possess a distinct subcellular compartment, the nucleus, separated from the cytoplasm in a manner that allows the precise operation of the chromatin, thereby permitting controlled access to the regulatory elements in the DNA for transcription and replication. In the cytoplasm, genetic information contained in the DNA sequence is translated into proteins, including enzymes that catalyze various reactions, such as metabolic processes, energy control, and responses to changing environments. One mechanism that regulates these events involves phosphoinositide turnover signaling, which generates a lipid second messenger, diacylglycerol (DG). Since DG acts as a potent activator of several signaling molecules, it should be tightly regulated to keep cellular responsiveness within a physiological range. DG kinase (DGK) metabolizes DG by phosphorylating it to generate phosphatidic acid, thus serving as a critical regulator of DG signaling. Phosphoinositide turnover is employed differentially in the nucleus and the cytoplasm. A member of the DGK family, DGKζ, localizes to the nucleus in various cell types and is considered to regulate nuclear DG signaling. Recent studies have provided evidence that DGKζ shuttles between the nucleus and the cytoplasm in neurons under pathophysiological conditions. Transport of a signal regulator between the nucleus and the cytoplasm should be a critical function for maintaining basic processes in the nucleus, such as cell cycle regulation and gene expression, and to ensure communication between nuclear processes and cytoplasmic functions. In this review, a series of studies on nucleocytoplasmic translocation of DGKζ have been summarized, and the functional implications of this phenomenon in postmitotic neurons and cancer cells under stress conditions are discussed.
Collapse
|
40
|
Sato M, Liu K, Sasaki S, Kunii N, Sakai H, Mizuno H, Saga H, Sakane F. Evaluations of the selectivities of the diacylglycerol kinase inhibitors R59022 and R59949 among diacylglycerol kinase isozymes using a new non-radioactive assay method. Pharmacology 2013; 92:99-107. [PMID: 23949095 DOI: 10.1159/000351849] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 04/30/2013] [Indexed: 11/19/2022]
Abstract
Ten mammalian diacylglycerol kinase (DGK) isozymes (α-κ) have been identified. Recent studies have revealed that DGK isozymes play pivotal roles in a wide variety of pathophysiological functions. Thus, it is important to be able to easily check DGK activity in each pathophysiological event. Moreover, the conventional DGK assay is quite laborious because it requires the use of a radioisotope and thin-layer chromatography including multiple extraction steps. In order to minimize the laborious procedures, we established a non-radioactive, single well, two-step DGK assay system. We demonstrated that, compared to the conventional method, the new assay system has comparable sensitivity and much higher efficiency, and is effective in detecting potential agents with high reliability (Z'-factor = 0.69 ± 0.12; n = 3). Using the newly developed assay, we comprehensively evaluated the DGK isozyme selectivities of commercially available DGK inhibitors, R59022 and R59949, in vitro. We found that among 10 isozymes, R59022 strongly inhibited type I DGKα and moderately attenuated type III DGKε and type V DGKθ, and that R59949 strongly inhibited type I DGK α and γ, and moderately attenuated type II DGK δ and κ.
Collapse
Affiliation(s)
- Mayu Sato
- Department of Chemistry, Graduate School of Science, Chiba University, Inage-ku, Chiba, Japan
| | | | | | | | | | | | | | | |
Collapse
|
41
|
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.
Collapse
Affiliation(s)
- Yasukazu Hozumi
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan.
| | | | | |
Collapse
|
42
|
Siniossoglou S. Phospholipid metabolism and nuclear function: Roles of the lipin family of phosphatidic acid phosphatases. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:575-81. [DOI: 10.1016/j.bbalip.2012.09.014] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 09/19/2012] [Accepted: 09/24/2012] [Indexed: 01/22/2023]
|
43
|
Matsutomo D, Isozaki T, Sakai H, Sakane F. Osmotic shock-dependent redistribution of diacylglycerol kinase η1 to non-ionic detergent-resistant membrane via pleckstrin homology and C1 domains. ACTA ACUST UNITED AC 2012; 153:179-90. [DOI: 10.1093/jb/mvs130] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
44
|
Induction of filopodia-like protrusions in N1E-115 neuroblastoma cells by diacylglycerol kinase γ independent of its enzymatic activity: potential novel function of the C-terminal region containing the catalytic domain of diacylglycerol kinase γ. Mol Cell Biochem 2012; 373:85-93. [PMID: 23054194 DOI: 10.1007/s11010-012-1477-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2012] [Accepted: 09/26/2012] [Indexed: 10/27/2022]
Abstract
Type I diacylglycerol kinase (DGK) isozymes (α, β, and γ) contain recoverin homology domains and calcium-binding EF-hand motifs at their N-termini. The γ-isoform of DGK is abundantly expressed in retinal and Purkinje cells; however, its function in neuronal cells remains unknown. Here, we report that the mRNA and protein levels of DGKγ, but not DGKα or β, were markedly increased in N1E-115 neuroblastoma cells upon cellular differentiation by serum starvation. Interestingly, overexpression of wild-type DGKγ, which was partially located at the plasma membrane, considerably induced the formation of slender, filopodia-like cytoplasmic projections from N1E-115 cell bodies. Deletion of the recoverin homology domain and the EF-hand motifs, which potentiated the plasma membrane localization of the isozyme, significantly enhanced the formation of the filopodia-like protrusions. Intriguingly, the catalytic activity of the isozyme is not essential for the protrusion formation. The N-terminal half of the catalytic domain and a short stretch of amino acid residues at the C-terminus are responsible for plasma membrane localization and filopodia-like process formation. Taken together, we have described a potentially novel morphological function of the C-terminal DGKγ catalytic region that is independent of its enzymatic activity.
Collapse
|
45
|
Diacylglycerol kinase δ1 transiently translocates to the plasma membrane in response to high glucose. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:2210-6. [PMID: 22974639 DOI: 10.1016/j.bbamcr.2012.08.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Revised: 08/21/2012] [Accepted: 08/27/2012] [Indexed: 01/21/2023]
Abstract
The type II diacylglycerol kinases (DGKs) contain several functional domains such as a pleckstrin homology (PH) domain, two C1 domains and a sterile α-motif (SAM) domain. It was previously revealed that DGKδ contributes to hyperglycemia-induced peripheral insulin resistance and thereby exacerbate the severity of type 2 diabetes. Moreover, a high extracellular concentration of glucose activated DGKδ in skeletal muscle cells, which was followed by a reduction in the intracellular diacylglycerol levels and the inactivation of protein kinase Cα, the enzyme that phosphorylates and inactivates the insulin receptor. However, the intracellular behavior of DGKδ upon high glucose stimulation remains unclear. In this study, we found that DGKδ1, but not a splice variant DGKδ2 or the other type II DGKη1/2, translocated from the cytoplasm to the plasma membrane in human embryonic kidney HEK293 and mouse myoblast C2C12 cells within 5 min in response to high glucose levels. The translocation was inhibited by phosphatidylinositol 3-kinase inhibitors, LY294002 and GDC-0941, suggesting that the event is regulated via the phosphatidylinositol 3-kinase pathway. Moreover, we revealed that the PH and C1 domains are responsible for the plasma membrane translocation and that the SAM domain negatively regulates the translocation. These results indicate that DGKδ1 is the sole type II DGK isoform that responds rapidly and dynamically to high glucose levels.
Collapse
|
46
|
Mizuno S, Sakai H, Saito M, Kado S, Sakane F. Diacylglycerol kinase-dependent formation of phosphatidic acid molecular species during interleukin-2 activation in CTLL-2 T-lymphocytes. FEBS Open Bio 2012; 2:267-72. [PMID: 23650609 PMCID: PMC3642166 DOI: 10.1016/j.fob.2012.08.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 08/16/2012] [Accepted: 08/20/2012] [Indexed: 02/02/2023] Open
Abstract
Although effective liquid chromatography (LC)/mass spectrometry (MS) methods enabling the separation of phospholipid molecular species have been developed, there are still problems with an intracellular signaling molecule, phosphatidic acid (PA). In this study, we optimized LC/MS conditions to improve the quantitative detection of PA molecular species from a cellular lipid mixture. Using the newly developed LC/MS method, we showed that stimulation of CTLL-2 murine T-lymphocytes by interleukin-2 (IL-2) induced a significant increase of 36:1-, 36:2-, 40:5- and 40:6-diacyl-PA. A diacylglycerol kinase (DGK) inhibitor, R59949, attenuated the increase of 36:1-, 40:5-, 40:6-diacyl-PA, suggesting that DGK IL-2-dependently and selectively generated these diacyl-PA species.
Collapse
Key Words
- DGK, diacylglycerol kinase
- DMEM, Dulbecco's modified Eagle's medium
- Diacylglycerol kinase
- ESI, electrospray ionization
- FBS, fetal bovine serum
- IL-2, interleukin-2
- Interleukin-2
- LC, liquid chromatography
- Liquid chromatography/electrospray-ionization mass spectrometry
- MEF, mouse embryonic fibroblast
- MS, mass spectrometry
- PA, phosphatidic acid
- PLD, phospholipase D.
- Phosphatidic acid
Collapse
Affiliation(s)
- Satoru Mizuno
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | | | | | | | | |
Collapse
|
47
|
Okada M, Hozumi Y, Tanaka T, Suzuki Y, Yanagida M, Araki Y, Evangelisti C, Yagisawa H, Topham MK, Martelli AM, Goto K. DGKζ is degraded through the cytoplasmic ubiquitin–proteasome system under excitotoxic conditions, which causes neuronal apoptosis because of aberrant cell cycle reentry. Cell Signal 2012; 24:1573-82. [DOI: 10.1016/j.cellsig.2012.03.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Accepted: 03/28/2012] [Indexed: 12/29/2022]
|
48
|
Takeishi K, Taketomi A, Shirabe K, Toshima T, Motomura T, Ikegami T, Yoshizumi T, Sakane F, Maehara Y. Diacylglycerol kinase alpha enhances hepatocellular carcinoma progression by activation of Ras-Raf-MEK-ERK pathway. J Hepatol 2012; 57:77-83. [PMID: 22425622 DOI: 10.1016/j.jhep.2012.02.026] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 02/02/2012] [Accepted: 02/13/2012] [Indexed: 12/27/2022]
Abstract
BACKGROUND & AIMS Diacylglycerol kinases (DGKs) were recently recognized as key regulators in cell signaling pathways. We investigated whether DGKα is involved in human hepatocellular carcinoma (HCC) progression. METHODS We silenced or overexpressed DGKα in HCC cells and assessed its effect on tumor progression. DGKα expression in 95 surgical samples was analyzed by immunohistochemistry, and the expression status of each sample was correlated with clinicopathological features. RESULTS DGKα was detected in various HCC cell lines but at very low levels in the normal liver. Knockdown of DGKα significantly suppressed cell proliferation and invasion. Overexpression of wild type (WT) DGKα, but not its kinase-dead (KD) mutant, significantly enhanced cell proliferation. DGKα knockdown impaired MEK and ERK phosphorylation, but did not inhibit Ras activation in HCC cells. In a xenograft model, WT DGKα overexpression significantly enhanced tumor growth compared to the control, but KD DGKα mutant had no effect. Immunohistochemical studies showed that DGKα was expressed in cancerous tissue, but not in adjacent non-cancerous hepatocytes. High DGKα expression (≥20%) was associated with high Ki67 expression (p<0.05) and a high rate of HCC recurrence (p=0.033) following surgery. In multivariate analyses, high DGKα expression was an independent factor for determining HCC recurrence after surgery. CONCLUSIONS DGKα is involved in HCC progression by activation of the MAPK pathway. DGKα could be a novel target for HCC therapeutics as well as a prognostic marker.
Collapse
Affiliation(s)
- Kazuki Takeishi
- Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
49
|
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.
Collapse
Affiliation(s)
- Masato Takahashi
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | | | | | | |
Collapse
|
50
|
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.
Collapse
Affiliation(s)
- Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|