1
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Suzuki R, Murakami C, Dilimulati K, Atsuta-Tsunoda K, Kawai T, Sakane F. Human sphingomyelin synthase 1 generates diacylglycerol in the presence and absence of ceramide via multiple enzymatic activities. FEBS Lett 2023; 597:2672-2686. [PMID: 37715942 DOI: 10.1002/1873-3468.14735] [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] [Received: 06/29/2023] [Revised: 08/24/2023] [Accepted: 09/01/2023] [Indexed: 09/18/2023]
Abstract
Sphingomyelin (SM) synthase 1 (SMS1), which is involved in lipodystrophy, deafness, and thrombasthenia, generates diacylglycerol (DG) and SM using phosphatidylcholine (PC) and ceramide as substrates. Here, we found that SMS1 possesses DG-generating activities via hydrolysis of PC and phosphatidylethanolamine (PE) in the absence of ceramide and ceramide phosphoethanolamine synthase (CPES) activity. In the presence of the same concentration (4.7 mol%) of PC and ceramide, the amounts of DG produced by SMS and PC-phospholipase C (PLC) activities of SMS1 were approximately 65% and 35% of total DG production, respectively. PC-PLC activity showed substrate selectivity for saturated and/or monounsaturated fatty acid-containing PC species. A PC-PLC/SMS inhibitor, D609, inhibited only SMS activity. Mn2+ inhibited only PC-PLC activity. Intriguingly, DG attenuated SMS/CPES activities. Our study indicates that SMS1 is a unique enzyme with PC-PLC/PE-PLC/SMS/CPES activities.
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Affiliation(s)
- Rika Suzuki
- Department of Chemistry, Graduate School of Science, Chiba University, Japan
| | - Chiaki Murakami
- Department of Chemistry, Graduate School of Science, Chiba University, Japan
- Institute for Advanced Academic Research, Chiba University, Japan
| | - Kamila Dilimulati
- Department of Chemistry, Graduate School of Science, Chiba University, Japan
| | | | - Takuma Kawai
- Department of Chemistry, Graduate School of Science, Chiba University, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Japan
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2
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Eurtivong C, Leung E, Sharma N, Leung IKH, Reynisson J. Phosphatidylcholine-Specific Phospholipase C as a Promising Drug Target. Molecules 2023; 28:5637. [PMID: 37570610 PMCID: PMC10420013 DOI: 10.3390/molecules28155637] [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] [Received: 05/19/2023] [Revised: 07/12/2023] [Accepted: 07/24/2023] [Indexed: 08/13/2023] Open
Abstract
Phosphatidylcholine-specific phospholipase C (PC-PLC) is an enzyme that catalyzes the formation of the important secondary messengers phosphocholine and diacylglycerol (DAG) from phosphatidylcholine. Although PC-PLC has been linked to the progression of many pathological conditions, including cancer, atherosclerosis, inflammation and neuronal cell death, studies of PC-PLC on the protein level have been somewhat neglected with relatively scarce data. To date, the human gene expressing PC-PLC has not yet been found, and the only protein structure of PC-PLC that has been solved was from Bacillus cereus (PC-PLCBc). Nonetheless, there is evidence for PC-PLC activity as a human functional equivalent of its prokaryotic counterpart. Additionally, inhibitors of PC-PLCBc have been developed as potential therapeutic agents. The most notable classes include 2-aminohydroxamic acids, xanthates, N,N'-hydroxyureas, phospholipid analogues, 1,4-oxazepines, pyrido[3,4-b]indoles, morpholinobenzoic acids and univalent ions. However, many medicinal chemistry studies lack evidence for their cellular and in vivo effects, which hampers the progression of the inhibitors towards the clinic. This review outlines the pathological implications of PC-PLC and highlights current progress and future challenges in the development of PC-PLC inhibitors from the literature.
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Affiliation(s)
- Chatchakorn Eurtivong
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Mahidol University, 447 Si Ayutthaya Road, Ratchathewi, Bangkok 10400, Thailand
| | - Euphemia Leung
- Auckland Cancer Society Research Centre, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand;
| | - Nabangshu Sharma
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand;
- Scion (New Zealand Forest Research Institute), Te Papa Tipu Innovation Park, 49 Sala Street, Rotorua 3010, New Zealand
| | - Ivanhoe K. H. Leung
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Rd, Parkville, VIC 3052, Australia;
| | - Jóhannes Reynisson
- School of Pharmacy and Bioengineering, Keele University, Newcastle-under-Lyme ST5 5BG, UK;
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3
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Sphingomyelin synthase-related protein generates diacylglycerol via the hydrolysis of glycerophospholipids in the absence of ceramide. J Biol Chem 2021; 296:100454. [PMID: 33621517 PMCID: PMC7988496 DOI: 10.1016/j.jbc.2021.100454] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 02/16/2021] [Accepted: 02/19/2021] [Indexed: 01/20/2023] Open
Abstract
Diacylglycerol (DG) is a well-established lipid second messenger. Sphingomyelin synthase (SMS)-related protein (SMSr) produces DG and ceramide phosphoethanolamine (CPE) by the transfer of phosphoethanolamine from phosphatidylethanolamine (PE) to ceramide. We previously reported that human SMSr overexpressed in COS-7 cells significantly increased DG levels, particularly saturated and/or monounsaturated fatty acid-containing DG molecular species, and provided DG to DG kinase (DGK) δ, which regulates various pathophysiological events, including epidermal growth factor-dependent cell proliferation, type 2 diabetes, and obsessive-compulsive disorder. However, mammalian SMSr puzzlingly produces only trace amounts of CPE/DG. To clarify this discrepancy, we highly purified SMSr and examined its activities other than CPE synthase. Intriguingly, purified SMSr showed a DG-generating activity via hydrolysis of PE, phosphatidic acid (PA), phosphatidylinositol (PI), and phosphatidylcholine (PC) in the absence of ceramide. DG generation through the PA phosphatase (PAP) activity of SMSr was approximately 300-fold higher than that with PE and ceramide. SMSr hydrolyzed PI ten times stronger than PI(4,5)bisphosphate (PI(4,5)P2). The PAP and PC-phospholipase C (PLC) activities of SMSr were inhibited by propranolol, a PAP inhibitor, and by D609, an SMS/PC-PLC inhibitor. Moreover, SMSr showed substrate selectivity for saturated and/or monounsaturated fatty acid-containing PA molecular species, but not arachidonic-acid-containing PA, which is exclusively generated in the PI(4,5)P2 cycle. We confirmed that SMSr expressed in COS-7 cells showed PAP and PI-PLC activities. Taken together, our study indicated that SMSr possesses previously unrecognized enzyme activities, PAP and PI/PE/PC-PLC, and constitutes a novel DG/PA signaling pathway together with DGKδ, which is independent of the PI(4,5)P2 cycle.
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4
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Sharma N, Langley RJ, Eurtivong C, Leung E, Dixon RJ, Paulin EK, Rees SWP, Pilkington LI, Barker D, Reynisson J, Leung IKH. An optimised MALDI-TOF assay for phosphatidylcholine-specific phospholipase C. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 13:491-496. [PMID: 33432952 DOI: 10.1039/d0ay02208j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The Bacillus cereus phosphatidylcholine-specific phospholipase C (PC-PLCBc) is an enzyme that catalyses the hydrolysis of phosphatidylcholines into phosphocholine and 1,2-diacylglycerols. PC-PLCBc has found applications in both the food industry and in medicinal chemistry. Herein, we report our work in the development and optimisation of a matrix assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry-based assay to monitor PC-PLCBc activity. The use of one-phase and two-phase reaction systems to assess the inhibition of PC-PLCBc with different structural classes of inhibitors was compared. We also highlighted the advantage of our assay over the commonly used commercially available Amplex Red assay. This method will also be applicable to work on the activity and inhibition of other phospholipases.
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Affiliation(s)
- Nabangshu Sharma
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Ries J Langley
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand and Department of Molecular Medicine and Pathology, School of Medical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
| | - Chatchakorn Eurtivong
- Program in Chemical Sciences, Chulabhorn Graduate Institute, Chulabhorn Royal Academy, Bangkok 10210, Thailand and Center of Excellence on Environmental Health and Toxicology (EHT), Commission on Higher Education (CHE), Ministry of Education, Bangkok 10400, Thailand
| | - Euphemia Leung
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand and Department of Molecular Medicine and Pathology, School of Medical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand and Auckland Cancer Society Research Centre, School of Medical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
| | - Ryan Joseph Dixon
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Emily K Paulin
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Shaun W P Rees
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Lisa I Pilkington
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - David Barker
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand. and Centre for Green Chemical Science, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand and The MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand
| | - Jóhannes Reynisson
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand. and School of Pharmacy and Bioengineering, Keele University, Staffordshire ST5 5BG, UK
| | - Ivanhoe K H Leung
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand. and Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand and Centre for Green Chemical Science, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
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5
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Lu Q, Murakami C, Murakami Y, Hoshino F, Asami M, Usuki T, Sakai H, Sakane F. 1‐Stearoyl‐2‐docosahexaenoyl‐phosphatidic acid interacts with and activates Praja‐1, the E3 ubiquitin ligase acting on the serotonin transporter in the brain. FEBS Lett 2020; 594:1787-1796. [DOI: 10.1002/1873-3468.13765] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/15/2020] [Accepted: 02/21/2020] [Indexed: 12/28/2022]
Affiliation(s)
- Qiang Lu
- Department of Chemistry Graduate School of Science Chiba University Chiba Japan
| | - Chiaki Murakami
- Department of Chemistry Graduate School of Science Chiba University Chiba Japan
| | - Yuki Murakami
- Department of Chemistry Graduate School of Science Chiba University Chiba Japan
| | - Fumi Hoshino
- Department of Chemistry Graduate School of Science Chiba University Chiba Japan
| | - Maho Asami
- Department of Chemistry Graduate School of Science Chiba University Chiba Japan
| | - Takako Usuki
- 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
| | - Fumio Sakane
- Department of Chemistry Graduate School of Science Chiba University Chiba Japan
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6
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Diacylglycerol kinase δ destabilizes serotonin transporter protein through the ubiquitin-proteasome system. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158608. [DOI: 10.1016/j.bbalip.2019.158608] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 12/13/2019] [Accepted: 12/27/2019] [Indexed: 01/27/2023]
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7
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Prymas K, Świątkowska A, Traczyk G, Ziemlińska E, Dziewulska A, Ciesielska A, Kwiatkowska K. Sphingomyelin synthase activity affects TRIF-dependent signaling of Toll-like receptor 4 in cells stimulated with lipopolysaccharide. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158549. [DOI: 10.1016/j.bbalip.2019.158549] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 09/10/2019] [Accepted: 09/25/2019] [Indexed: 01/08/2023]
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8
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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.
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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.
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9
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Phospholipid molecular species composition of Chinese traditional low-salt fermented fish inoculated with different starter cultures. Food Res Int 2018; 111:87-96. [DOI: 10.1016/j.foodres.2018.05.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 05/05/2018] [Accepted: 05/08/2018] [Indexed: 01/20/2023]
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10
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Holme M, Rashid MH, Thomas MR, Barriga HMG, Herpoldt K, Heenan RK, Dreiss CA, Bañuelos JL, Xie HN, Yarovsky I, Stevens MM. Fate of Liposomes in the Presence of Phospholipase C and D: From Atomic to Supramolecular Lipid Arrangement. ACS CENTRAL SCIENCE 2018; 4:1023-1030. [PMID: 30159399 PMCID: PMC6107861 DOI: 10.1021/acscentsci.8b00286] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Indexed: 05/04/2023]
Abstract
Understanding the origins of lipid membrane bilayer rearrangement in response to external stimuli is an essential component of cell biology and the bottom-up design of liposomes for biomedical applications. The enzymes phospholipase C and D (PLC and PLD) both cleave the phosphorus-oxygen bonds of phosphate esters in phosphatidylcholine (PC) lipids. The atomic position of this hydrolysis reaction has huge implications for the stability of PC-containing self-assembled structures, such as the cell wall and lipid-based vesicle drug delivery vectors. While PLC converts PC to diacylglycerol (DAG), the interaction of PC with PLD produces phosphatidic acid (PA). Here we present a combination of small-angle scattering data and all-atom molecular dynamics simulations, providing insights into the effects of atomic-scale reorganization on the supramolecular assembly of PC membrane bilayers upon enzyme-mediated incorporation of DAG or PA. We observed that PC liposomes completely disintegrate in the presence of PLC, as conversion of PC to DAG progresses. At lower concentrations, DAG molecules within fluid PC bilayers form hydrogen bonds with backbone carbonyl oxygens in neighboring PC molecules and burrow into the hydrophobic region. This leads initially to membrane thinning followed by a swelling of the lamellar phase with increased DAG. At higher DAG concentrations, localized membrane tension causes a change in lipid phase from lamellar to the hexagonal and micellar cubic phases. Molecular dynamics simulations show that this destabilization is also caused in part by the decreased ability of DAG-containing PC membranes to coordinate sodium ions. Conversely, PLD-treated PC liposomes remain stable up to extremely high conversions to PA. Here, the negatively charged PA headgroup attracts significant amounts of sodium ions from the bulk solution to the membrane surface, leading to a swelling of the coordinated water layer. These findings are a vital step toward a fundamental understanding of the degradation behavior of PC lipid membranes in the presence of these clinically relevant enzymes, and toward the rational design of diagnostic and drug delivery technologies for phospholipase-dysregulation-based diseases.
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Affiliation(s)
- Margaret
N. Holme
- Department
of Materials, Imperial College London, London SW7 2AZ, United Kingdom
- Department of Bioengineering and Institute of Biomedical
Engineering, Imperial College London, London SW7 2AZ, United Kingdom
- Department
of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - M. Harunur Rashid
- School
of Engineering, RMIT University, Melbourne, Victoria 3001, Australia
| | - Michael R. Thomas
- Department
of Materials, Imperial College London, London SW7 2AZ, United Kingdom
- Department of Bioengineering and Institute of Biomedical
Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Hanna M. G. Barriga
- Department
of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Karla−Luise Herpoldt
- Department
of Materials, Imperial College London, London SW7 2AZ, United Kingdom
- Department of Bioengineering and Institute of Biomedical
Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Richard K. Heenan
- STFC ISIS
Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom
| | - Cécile A. Dreiss
- School
of Cancer and Pharmaceutical Sciences, King’s
College London, London SE1 9NH, United Kingdom
| | - José Leobardo Bañuelos
- STFC ISIS
Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom
- Department
of Physics, The University of Texas at El
Paso, El Paso, Texas 79968, United States
| | - Hai-nan Xie
- Department
of Materials, Imperial College London, London SW7 2AZ, United Kingdom
- Department of Bioengineering and Institute of Biomedical
Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Irene Yarovsky
- School
of Engineering, RMIT University, Melbourne, Victoria 3001, Australia
- E-mail:
| | - Molly M. Stevens
- Department
of Materials, Imperial College London, London SW7 2AZ, United Kingdom
- Department of Bioengineering and Institute of Biomedical
Engineering, Imperial College London, London SW7 2AZ, United Kingdom
- Department
of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
- E-mail:
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11
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Sakai H, Murakami C, Matsumoto KI, Urano T, Sakane F. Diacylglycerol kinase δ controls down-regulation of cyclin D1 for C2C12 myogenic differentiation. Biochimie 2018; 151:45-53. [PMID: 29859210 DOI: 10.1016/j.biochi.2018.05.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Accepted: 05/28/2018] [Indexed: 12/25/2022]
Abstract
Diacylglycerol kinase (DGK) is a lipid-metabolizing enzyme that phosphorylates diacylglycerol (DG) to produce phosphatidic acid (PA). DGKδ is highly expressed in the skeletal muscle, and a decrease in DGKδ expression increases the severity of type 2 diabetes. However, the role of DGKδ in myogenic differentiation is still unknown. The present study demonstrated that DGKδ expression was down-regulated in the early stage of C2C12 myogenic differentiation almost concurrently with a decrease in cyclin D1 expression. The knockdown of DGKδ by DGKδ-specific siRNAs significantly increased the levels of cyclin D1 expression at 48 h after C2C12 myogenic differentiation. In contrast, at the same time, the knockdown of DGKδ decreased the levels of myogenin expression and the number of myosin heavy chain (MHC)-positive cells. These results indicate that DGKδ regulates the early differentiation of C2C12 myoblasts via controlling the down-regulation of cyclin D1 expression. Moreover, the suppression of DGKδ expression increased the phosphorylation levels of conventional and novel protein kinase Cs (cnPKCs). Furthermore, DGKδ suppression increased the levels of cyclin D1 and phospho-cnPKCs even at the first 24 h of myogenic differentiation. These results suggest that DGKδ controls the down-regulation of cyclin D1 expression by attenuating the PKC signaling pathway for C2C12 myogenic differentiation.
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Affiliation(s)
- Hiromichi Sakai
- Department of Biosignaling and Radioisotope Experiment, Interdisciplinary Center for Science Research, Organization for Research and Academic Information, Shimane University, Izumo, Japan.
| | - Chiaki Murakami
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Ken-Ichi Matsumoto
- Department of Biosignaling and Radioisotope Experiment, Interdisciplinary Center for Science Research, Organization for Research and Academic Information, Shimane University, Izumo, Japan
| | - Takeshi Urano
- Department of Biosignaling and Radioisotope Experiment, Interdisciplinary Center for Science Research, Organization for Research and Academic Information, Shimane University, Izumo, Japan; Department of Biochemistry, Shimane University School of Medicine, Izumo, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan.
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