1
|
Lum MA, Barger CJ, Hsu AH, Leontieva OV, Black AR, Black JD. Protein Kinase Cα (PKCα) Is Resistant to Long Term Desensitization/Down-regulation by Prolonged Diacylglycerol Stimulation. J Biol Chem 2016; 291:6331-46. [PMID: 26769967 DOI: 10.1074/jbc.m115.696211] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Indexed: 11/06/2022] Open
Abstract
Sustained activation of PKCα is required for long term physiological responses, such as growth arrest and differentiation. However, studies with pharmacological agonists (e.g. phorbol 12-myristate 13-acetate (PMA)) indicate that prolonged stimulation leads to PKCα desensitization via dephosphorylation and/or degradation. The current study analyzed effects of chronic stimulation with the physiological agonist diacylglycerol. Repeated addition of 1,2-dioctanoyl-sn-glycerol (DiC8) resulted in sustained plasma membrane association of PKCα in a pattern comparable with that induced by PMA. However, although PMA potently down-regulated PKCα, prolonged activation by DiC8 failed to engage known desensitization mechanisms, with the enzyme remaining membrane-associated and able to support sustained downstream signaling. DiC8-activated PKCα did not undergo dephosphorylation, ubiquitination, or internalization, early events in PKCα desensitization. Although DiC8 efficiently down-regulated novel PKCs PKCδ and PKCϵ, differences in Ca(2+) sensitivity and diacylglycerol affinity were excluded as mediators of the selective resistance of PKCα. Roles for Hsp/Hsc70 and Hsp90 were also excluded. PMA, but not DiC8, targeted PKCα to detergent-resistant membranes, and disruption of these domains with cholesterol-binding agents demonstrated a role for differential membrane compartmentalization in selective agonist-induced degradation. Chronic DiC8 treatment failed to desensitize PKCα in several cell types and did not affect PKCβI; thus, conventional PKCs appear generally insensitive to desensitization by sustained diacylglycerol stimulation. Consistent with this conclusion, prolonged (several-day) membrane association/activation of PKCα is seen in self-renewing epithelium of the intestine, cervix, and skin. PKCα deficiency affects gene expression, differentiation, and tumorigenesis in these tissues, highlighting the importance of mechanisms that protect PKCα from desensitization in vivo.
Collapse
Affiliation(s)
- Michelle A Lum
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Carter J Barger
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and
| | - Alice H Hsu
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and
| | - Olga V Leontieva
- the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Adrian R Black
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Jennifer D Black
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| |
Collapse
|
2
|
Khatri M, Sharma JM. Response of embryonic chicken lymphoid cells to infectious bursal disease virus. Vet Immunol Immunopathol 2009; 127:316-24. [DOI: 10.1016/j.vetimm.2008.10.327] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Revised: 10/16/2008] [Accepted: 10/20/2008] [Indexed: 11/16/2022]
|
3
|
Pacheco ME, Beltrán A, Redondo J, Manso AM, Alonso MJ, Salaices M. High glucose enhances inducible nitric oxide synthase expression. Role of protein kinase C-betaII. Eur J Pharmacol 2006; 538:115-23. [PMID: 16631733 DOI: 10.1016/j.ejphar.2006.03.052] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Accepted: 03/20/2006] [Indexed: 10/24/2022]
Abstract
The aim was to determine whether high glucose levels interfere with nitric oxide (NO) production and inducible NO synthase (iNOS) protein expression in interleukin-1beta-stimulated vascular smooth muscle cells from normotensive Wistar Kyoto and spontaneously hypertensive rats. Cells were incubated with either normal (5.5 mM) or high (22 mM) d-glucose for 72 h and with interleukin-1beta (10 ng/ml) for the last 24 h. High glucose increased nitrite levels, iNOS expression and protein kinase C activity in cells from normotensive rats and had no effect in cells from hypertensive rats. High glucose effects on nitrite production and iNOS expression was abolished by the selective inhibitor for the protein kinase C-betaII, 5,21:12,17-dimetheno-18H-dibenzo[i,o]pyrrolo[3,4-1] [1,8]diacyclohexadecine-18,20 (19H)-dione, 8-[(dimethylamino) methyl]-6,7,8,9,10,11-hexahydro-monomethanesulfonate (LY379196, 30 nM). Calphostin C (1 microM) and LY379196 (10 microM) reduced nitrite levels and iNOS expression only in cells from normotensive rats treated with both media. These results suggest that high glucose increases inducible nitric oxide synthase induction and subsequent NO production by activating the protein kinase C-betaII; this mechanism seems to be altered in hypertension.
Collapse
MESH Headings
- Animals
- Aorta, Thoracic/cytology
- Blotting, Western
- Cells, Cultured
- Dose-Response Relationship, Drug
- Enzyme Inhibitors/pharmacology
- Glucose/pharmacology
- Interleukin-1/pharmacology
- Male
- Mesylates/pharmacology
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Naphthalenes/pharmacology
- Nitric Oxide/biosynthesis
- Nitric Oxide Synthase Type II/biosynthesis
- Protein Kinase C/antagonists & inhibitors
- Protein Kinase C/metabolism
- Protein Kinase C/physiology
- Protein Kinase C beta
- Pyrroles/pharmacology
- Rats
- Rats, Inbred SHR
- Rats, Inbred WKY
- Tetradecanoylphorbol Acetate/pharmacology
Collapse
Affiliation(s)
- María E Pacheco
- Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo 4, 28029 Madrid, Spain
| | | | | | | | | | | |
Collapse
|
4
|
Peters MA, Browning GF, Washington EA, Crabb BS, Kaiser P. Embryonic age influences the capacity for cytokine induction in chicken thymocytes. Immunology 2003; 110:358-67. [PMID: 14632664 PMCID: PMC1783060 DOI: 10.1046/j.1365-2567.2003.01744.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thymocyte responses to functional activation are of relevance to the evaluation of the efficacy of in ovo immunotherapies and vaccines in chickens. In this study we have demonstrated differences in chicken thymocyte responses according to developmental age. RNA samples from stimulated and unstimulated chicken thymocytes were assayed for messenger RNA encoding the cytokines interleukin-1beta (IL-1beta), IL-2, interferon-alpha (IFN-alpha), IFN-beta, IFN-gamma and transforming growth factor-beta4 (TGF-beta4), and also components of the major histocompatibility complex (MHC), beta2-microglobulin (beta2M) and the MHC class I alpha-chain (MHC IA). At embryonic day 14 thymocytes were least responsive to functional activation and differences existed even between thymocyte populations at embryonic day 18 and day 1 post-hatch. The duration of proliferation in response to stimulation was found to increase with increasing embryonic age. Mitogen stimulation of embryonic day 18 and day 1 post-hatch thymocytes induced up-regulation of IFN-gamma, IL-1beta and TGF-beta transcripts, and down-regulation of IFN-alpha, IFN-beta and IL-2 transcripts, with a higher induction of IFN-gamma, IL-1beta and TGF-beta transcripts in more immature T-cell-receptor-negative (TCR-) than TCR+ (TCR1+, TCR2+, or TCR3+) subsets. In contrast, in the mouse and human, both mature and immature thymocytes respond to mitogen stimulation with up-regulation of IL-2. Thymocytes from embryonic day 14 chicks responded to mitogen with a short burst of unsustained proliferation, and transcriptional down-regulation of the cytokines IL-2, IL-1beta, IFN-alpha, IFN-beta and IFN-gamma. These results suggest that embryonic day 14 thymocytes are largely unresponsive to mitogen. Transcripts encoding TGF-beta and type I interferons (IFN-alpha and IFN-beta) were constitutively expressed at high levels in very early thymocytes at embryonic day 14. Thymocytes at embryonic days 14 and 18 and day 1 post-hatch responded to mitogen stimulation with up-regulation of MHC IA transcript. The pattern of beta2M transcription following mitogen stimulation was distinct from that of the globally up-regulated MHC IA transcript, with up-regulation of beta2M transcription observed at embryonic day 18 and day 1 post-hatch but not at embryonic day 14. In thymocyte subsets, up-regulation of beta2M transcription was found to be specific to the CD8+ TCR+ population. The balance of responses in the embryonic thymus suggests that at all stages thymocytes have a reduced capacity for activation in comparison to mature thymocyte populations.
Collapse
Affiliation(s)
- Michelle A Peters
- Department of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia
| | | | | | | | | |
Collapse
|
5
|
Chakrabarti R, Kumar S. Diacylglycerol mediates the T-cell receptor-driven Ca2+ influx in T cells by a novel mechanism independent of protein kinase C activation. J Cell Biochem 2000. [DOI: 10.1002/(sici)1097-4644(20000801)78:2<222::aid-jcb5>3.0.co;2-p] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
6
|
Kumar S, Chakrabarti R. [8-(Diethylamino)octyl-3,4,5-trimethoxybenzoate, HCl], the inhibitor of intracellular calcium mobilization, blocked mitogen-induced T cell proliferation by interfering with the sustained phase of protein kinase C activation. J Cell Biochem 2000; 76:539-47. [PMID: 10653973 DOI: 10.1002/(sici)1097-4644(20000315)76:4<539::aid-jcb2>3.0.co;2-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The physiological role of IP(3)-dependent Ca(2+) release in T cell activation was in question due to the contradictory findings that [8-(Diethylamino)octyl-3,4,5-trimethoxybenzoate, HCl] (TMB-8), an inhibitor of intracellular Ca(2+) mobilization, blocked T cell proliferation, curtailing specifically the level of released Ca(2+) did not affect T cell activation and T cell line lacking IP(3) receptor was defective in IL-2 production in response to TCR/CD3 ligand. In the present study we found that TMB-8 inhibited Concanavalin A (Con A)- but not PMA/Ionomycin-induced T cell proliferation in a reversible and dose-dependent manner. The kinetic study revealed that TMB-8 exerted the inhibitory effect at a very early step of T cell activation. The Ca(2+) ionophore ionomycin augmented instead of overcoming the inhibitory effect of TMB-8, although the same doses of ionomycin alone had no effect on Con A-induced T cell proliferation. PMA the metabolically stable, but not diacylglycerol (DAG) the metabolically labile, activator of protein Kinase C (PKC) completely overcome the antiproliferative effect of TMB-8. A specific DAG lipase inhibitor RHC80267 also overcome the effect of TMB-8. Taken together, these results showed that the process of Ca(2+) release through IP(3) receptor, not the released Ca(2+), is essential for the sustained phase of PKC activation during T cell proliferation.
Collapse
Affiliation(s)
- S Kumar
- Molecular Biology Unit, Institute of Medical Sciences, Banaras Hindu University, Varanasi-221005, India
| | | |
Collapse
|
7
|
Yan Z, Yang DC, Neill R, Jett M. Production of tumor necrosis factor alpha in human T lymphocytes by staphylococcal enterotoxin B correlates with toxin-induced proliferation and is regulated through protein kinase C. Infect Immun 1999; 67:6611-8. [PMID: 10569782 PMCID: PMC97074 DOI: 10.1128/iai.67.12.6611-6618.1999] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/1999] [Accepted: 08/16/1999] [Indexed: 11/20/2022] Open
Abstract
The superantigen staphylococcal enterotoxin B (SEB) simultaneously binds both the major histocompatibility complex (MHC) class II receptor on monocytes and the T-cell receptor (TCR) on T lymphocytes, resulting in a range of cell responses including induction of tumor necrosis factor alpha (TNF-alpha). In this study, we have used mixed cultures of human peripheral blood monocytes and lymphocytes to investigate biochemical events controlling SEB induction of TNF-alpha. TNF-alpha production induced by SEB in mixed cultures is more closely associated with T cells than with monocytes: (i) a TCR-binding-site mutant of SEB (N23F) is less active in TNF-alpha induction than an MHC class II receptor-binding-site mutant (F44R), and (ii) flow cytometric analysis indicated that SEB induced TNF-alpha production in T cells but not in monocytes. Pretreatment of cells with inhibitors of signal transduction pathways was employed to further define events in SEB-induced TNF-alpha production. Neither protein kinase A inhibitors nor two protein tyrosine kinase inhibitors altered SEB-induced TNF-alpha production. In contrast, SEB induced protein kinase C (PKC) translocation, and pretreatment of cultures with inhibitors of PKC blocked TNF-alpha induction. Alteration of levels of diacylglycerol (DAG), an activator of PKC, by treatment with inhibitors of phospholipase C or DAG kinase also altered SEB-induced TNF-alpha production. These data suggest that PKC activation plays a critical role in SEB-induced TNF-alpha production in human T cells.
Collapse
Affiliation(s)
- Z Yan
- Chemistry Department, Georgetown University, Washington, D.C. 20056, USA
| | | | | | | |
Collapse
|
8
|
Khan NA, Hichami A. Ionotrophic 5-hydroxytryptamine type 3 receptor activates the protein kinase C-dependent phospholipase D pathway in human T-cells. Biochem J 1999; 344 Pt 1:199-204. [PMID: 10548551 PMCID: PMC1220631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
The present study was undertaken to investigate the role of the 5-hydroxytryptamine (5-HT) ionotrophic receptor 5-HT(3) in the activation of human Jurkat T-cells. 5-HT and 2-methyl-5-HT (2Me-5-HT), an agonist of the 5-HT(3) receptor, induced increases in intracellular free Na(+) concentrations, [Na(+)](i), via opening of the ionotrophic receptor in these cells. These two serotonergic (5-hydroxytryptaminergic) agents potentiated phytohaemagglutinin (PHA)-induced T-cell activation. However, they failed to potentiate dioctanoglycerol-plus-ionomycin-stimulated T-cell blastogenesis. Interestingly, an inhibitor of protein kinase C (PKC), GF 109203X, curtailed significantly 5-HT and 2Me-5-HT-potentiated T-cell activation. These results demonstrate that the opening of the 5-HT(3) ionotrophic receptor is implicated in T-cell activation via the PKC pathway. Furthermore, 5-HT and 2Me-5-HT stimulated phospholipase D (PLD) activity, as measured by the production of phosphatidylethanol and phosphatidylbutanol at the expense of phosphatidic acid (PA). GF 109203X significantly curtailed the 5-HT- and 2Me-5-HT-induced PLD activity and T-cell activation. The PLD/PA pathway stimulated by these two serotonergic agents resulted in the production of 1,2-diacylglycerol (DAG) mass in Jurkat T-cells. These results altogether suggest that 5-HT and 2Me-5-HT potentiate T-cell activation via increases in [Na(+)](i) and the activation of the PKC-dependent PLD pathway.
Collapse
Affiliation(s)
- N A Khan
- UPRES Lipides et Nutrition, Université de Bourgogne, Faculté des Sciences-Mirande, 9 avenue Alain Savary, 21011 Dijon Cedex, France.
| | | |
Collapse
|
9
|
Abstract
Stimulation of T cells by the T-cell receptor (TCR)/CD3 complex results in interleukin-2 (IL-2) synthesis and surface expression of the IL-2 receptor (IL-2R), which in turn drive T-cell proliferation. However, the significance of the requirement of IL-2 in driving T-cell proliferation, when TCR stimulation itself delivers potential mitogenic signals, is unclear. We show that blocking of IL-2 synthesis by Cyclosporin A (CsA) suppressed both the Concanavalin A (Con A)- and phorbol myristate acetate (PMA)/ionomycin-induced proliferation of T cells. The latter is also inhibited by anti-IL-2R. Kinetic studies showed that T-cell proliferation begins to become resistant to CsA inhibition by about 12 h and became largely resistant by 18 h of stimulation. PMA, the protein kinase C activator, enhanced Con A-induced T-cell proliferation if added only within first 12 h of stimulation, and not after that. Given the fact that, in the present study, TCR is downregulated within 2 h of Con A stimulation and T cells entered the S phase of cell cycle by about 18 h of stimulation, the above results suggest that TCR stimulation provides the initial trigger to the resting T cells, which allows the cells to traverse the first two third portions of G1 phase of cell cycle and become proliferation competent. IL-2 action begins afterward, delivering the actual proliferation signal(s), allowing the cells to traverse the rest of G1 phase and enter the S phase of the cell cycle.
Collapse
Affiliation(s)
- R Chakrabarti
- Molecular Biology Unit, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India
| | | | | |
Collapse
|
10
|
Abstract
Diacylglycerol kinase (DGK) phosphorylates the second messenger diacylglycerol (DAG) to phosphatidic acid. A family of nine mammalian isotypes have been identified. Their primary structure shows a diverse array of conserved domains, such as a catalytic domain, zinc fingers, pleckstrin homology domains and EF-hand structures, known to interact with other proteins, lipids or Ca2+, in signal transduction processes. DGK is believed to act in the phosphoinositide cycle in which DAG is enriched with arachidonoyl moieties, but the majority of DGK isotypes do not show specificity for this DAG species in vitro. This could imply that DGKs may also have other functions in the cell. DGK activity is not only found in membranes, but also in the nucleus and at the cytoskeleton. Agonist-induced translocations of DGK to or from these subcellular sites are known to occur. Some isotypes are contained in signaling complexes in specific association with members of the Rho family of small GTP binding proteins, suggesting that they are involved in Rho-mediated processes such as cytoskeletal reorganization.
Collapse
Affiliation(s)
- W J van Blitterswijk
- Division of Cellular Biochemistry, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
| | | |
Collapse
|
11
|
Kaul PN. Drug discovery: past, present and future. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1998; 50:9-105. [PMID: 9670776 DOI: 10.1007/978-3-0348-8833-2_1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
New drug discovery from early on involved a trial-and-error approach on naturally derived materials and substances until the end of the nineteenth century. The first half of the twentieth century witnessed systematic pharmacological evaluations of both natural and synthetic compounds. However, most new drugs until the 1970s were discovered by serendipity. With the exponential development of molecular biology on one hand and computer technology on the other, it became possible from 1980 onwards to place drug discovery on a rational basis. Cloning of genes has led to the development of methodologies for specific receptor-directed and enzyme-directed drug discoveries. Advances in recombinant DNA and transgenic technologies have enabled the production of human hormonal and other endogenous biomolecules as new drugs. As we understand more about the co-ordinating and regulating powers of the cerebral cortex during the next century, especially of the frontal lobe, man may be able to use bio-feedback training to voluntarily regulate the release of neurotransmitters, hormones, and other molecules involved in the regulation of various physiological processes in health as well as in disease.
Collapse
Affiliation(s)
- P N Kaul
- Clark Atlanta University, GA 30314, USA
| |
Collapse
|
12
|
Chuang M, Severson DL. Metabolic fate of exogenous diacylglycerols in A10 smooth muscle cells. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1390:149-59. [PMID: 9507099 DOI: 10.1016/s0005-2760(97)00173-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The metabolic fate of exogenous diacylglycerols, 1-palmitoyl-2-[1-14C]oleoyl-sn-glycerol (2-[14C]POG) and 1-stearoyl-2-[1-14C]arachidonoyl-sn-glycerol (2-[14C]SAG), was determined after incubation of A10 smooth muscle cells with liposomal suspensions. Hydrolysis through a diacylglycerol (DG) lipase pathway was the predominant metabolic fate; more than 80% of cell-associated radioactivity from 2-[14C]POG and 2-[14C]SAG was recovered in lipolytic products, monoacylglycerol (MG) and fatty acids (FA), which were present in the incubation medium. Hydrolysis of 2-[14C]POG was reduced completely by tetrahydrolipstatin, a lipase inhibitor. Very little radioactivity from either 2-[14C]POG or 2-[14C]SAG was incorporated into triacylglycerol or phospholipids. DG lipase and kinase activities were measured by in vitro enzyme assays. 1-[1-14C]Palmitoyl-2-oleoyl-sn-glycerol (1-[14C]POG) was phosphorylated (kinase activity) to a greater extent than 2-[14C]SAG in assays with both soluble and particulate subcellular fractions from A10 cells. DG lipase activity (hydrolysis of 1-[14C]POG and 2-[14C]SAG) was markedly stimulated by the addition of 20 mM MgCl2 and 20 mM ATP to the assay. Under optimal assay conditions, DG lipase activity exhibited little substrate specificity. Our findings indicate that exogenous DG are mainly hydrolyzed by DG and MG lipases in A10 smooth muscle cells; as a result, signalling mechanisms responding to DG second messengers will be attenuated.
Collapse
Affiliation(s)
- M Chuang
- Smooth Muscle Research Group, Faculty of Medicine, The University of Calgary, 3330 Hospital Drive NW, Calgary, Alta., Canada
| | | |
Collapse
|
13
|
Muniyappa R, Srinivas PR, Ram JL, Walsh MF, Sowers JR. Calcium and protein kinase C mediate high-glucose-induced inhibition of inducible nitric oxide synthase in vascular smooth muscle cells. Hypertension 1998; 31:289-95. [PMID: 9453318 DOI: 10.1161/01.hyp.31.1.289] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Abnormal vascular smooth muscle (VSMC) proliferation is a key feature in diabetes-associated atherosclerotic disease. Since nitric oxide inhibits VSMC tone, migration, adhesion, and proliferation, we examined the effects of high glucose on IL-1beta-induced NO release from VSMCs in culture. Confluent smooth muscle cells, preincubated with either 5 mmol/L (mM) or 20 mmol/L (mM) glucose for 48 hours, were stimulated with IL-1beta. Nitrite was measured in the culture medium after 24 hours. IL-1beta-induced a 15-fold increase in NO production in normal glucose medium. Glucose (10 to 30 mmol/L (mM)) significantly reduced the response to IL-1beta. High glucose (20 mmol/L (mM)) inhibited IL-1beta-evoked NO production by approximately 50%. IL-1beta-stimulated [3H] citrulline-forming activity of the nitric oxide synthase (NOS) was also significantly lower in high-glucose-exposed cells, and this was reflected in diminished cellular levels of NOS protein. To assess the role of protein kinase C (PKC), membrane PKC activity was measured, and glucose (20 mmol/L (mM)) significantly increased it. Immunoblotting of the membranes revealed a glucose-induced increase in the PKC betaII isoform. 1,2-Dioctanoyl-glycerol, a PKC activator, mimicked the high-glucose effect on IL-1beta-induced NO release, while staurosporine, a PKC inhibitor, reversed it. The role of calcium in the glucose-mediated inhibition of cytokine-induced NO release was determined by treatment with BAPTA, an intracellular chelator of calcium. BAPTA partially reversed the inhibitory effects of glucose. Increasing intracellular calcium by A23187, an ionophore or thapsigargin, an inhibitor of endoplasmic reticulum Ca2+-ATPase, significantly decreased IL-1beta-induced NO release and NOS expression. These results indicate that glucose-induced inhibition of IL-1beta-stimulated NO release and NOS expression may be mediated by PKC activation and increased intracellular calcium.
Collapse
MESH Headings
- Animals
- Aorta, Thoracic/cytology
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/enzymology
- Calcium/metabolism
- Cell Membrane/enzymology
- Cells, Cultured
- Chelating Agents/pharmacology
- Egtazic Acid/analogs & derivatives
- Egtazic Acid/pharmacology
- Enzyme Induction/drug effects
- Glucose/pharmacology
- Interleukin-1/pharmacology
- Isoenzymes/metabolism
- Kinetics
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Nitric Oxide/biosynthesis
- Nitric Oxide Synthase/biosynthesis
- Nitric Oxide Synthase Type II
- Protein Kinase C/metabolism
- Rats
- Rats, Sprague-Dawley
- Time Factors
Collapse
Affiliation(s)
- R Muniyappa
- Department of Physiology, Wayne State University School of Medicine and VA Medical Center, Detroit, Michigan 48201, USA
| | | | | | | | | |
Collapse
|
14
|
Migas I, Chuang M, Sasaki Y, Severson DL. Diacylglycerol metabolism in SM-3 smooth muscle cells. Can J Physiol Pharmacol 1997. [DOI: 10.1139/y97-158] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
15
|
Jolly CA, Jiang YH, Chapkin RS, McMurray DN. Dietary (n-3) polyunsaturated fatty acids suppress murine lymphoproliferation, interleukin-2 secretion, and the formation of diacylglycerol and ceramide. J Nutr 1997; 127:37-43. [PMID: 9040541 DOI: 10.1093/jn/127.1.37] [Citation(s) in RCA: 190] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Elucidation of the mechanism(s) by which dietary fish oil, enriched in eicosapentaenoic acid (EPA, 20:5(n-3)] and docosahexaenoic acid [DHA, 22:6(n-3)], suppresses the inflammatory process is essential in maximizing this potentially therapeutic effect. Murine T-lymphocyte function and signal transduction were examined in response to a low fat, short term diet enriched in highly purified EPA or DHA ethyl esters. For 10 d, mice were fed comparable diets containing either 3% safflower oil ethyl esters (SAF), 2% SAF + 1% arachidonic acid triglyceride (AA), 2% SAF + 1% EPA, or 2% SAF + 1% DHA. Concanavalin A-induced T-lymphocyte proliferation in splenocyte cultures was significantly suppressed by dietary EPA and DHA while AA had no effect relative to the SAF control. The suppressed proliferative response in EPA- and DHA-fed mice was preceded temporally by a significant reduction in IL-2 secretion. Kinetics of mitogen-induced diacyl-sn-glycerol (DAG) and ceramide production did not differ significantly between SAF and AA diet groups. In contrast, DAG production was significantly suppressed in EP- and DHA-fed mice relative to the SAF and AA groups. The reduced DAG mass was paralleled by reduced ceramide mass following EPA and DHA feeding compared to the SAF and AA groups. Thus, low dose, short term dietary exposure to highly purified EPA or DHA appears to suppress mitogen-induced T-lymphocyte proliferation by inhibiting IL-2 secretion, and these events are accompanied by reductions in the production of essential lipid second messengers, DAG and ceramide.
Collapse
Affiliation(s)
- C A Jolly
- Faculty of Nutrition, Molecular and Cell Biology Group, College of Medicine, Texas A&M University, College Station 77843, USA
| | | | | | | |
Collapse
|
16
|
Migas I, Severson DL. Diacylglycerols derived from membrane phospholipids are metabolized by lipases in A10 smooth muscle cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 271:C1194-202. [PMID: 8897825 DOI: 10.1152/ajpcell.1996.271.4.c1194] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The metabolic fate of endogenous diacylglycerol (DAG) in cultured A10 smooth muscle cells was determined. Preincubation of A10 cells with [3H]myristic acid or [3H]arachidonic acid resulted in preferential labeling of phosphatidylcholine (PC) or phosphatidylinositol (PI), respectively. Addition of PC-specific phospholipase C (PC-PLC) to [3H]myristate-labeled A10 cells resulted in a 10-fold increase in radiolabeled DAG, which was converted to monoacylglycerol (MG) and fatty acid (FA). DAG degradation and MG formation was inhibited by tetrahydrolipstatin, a DAG lipase inhibitor. PC-derived DAG was not converted to phosphatidic acid; in addition, PC resynthesis or triacylglycerol synthesis was not observed. Addition of PI-specific PLC (PI-PLC) to [3H]arachidonate-labeled A10 cells resulted in a modest increase in radiolabeled DAG that was also hydrolyzed to MG and FA. Therefore, the principal metabolic fate of endogenous DAG generated from membrane phospholipids by treatment of A10 cells with PC-PLC and PI-PLC was hydrolysis by a DAG lipase pathway.
Collapse
Affiliation(s)
- I Migas
- Smooth Muscle Research Group, Faculty of Medicine, University of Calgary, Alberta, Canada
| | | |
Collapse
|
17
|
Wada I, Kai M, Imai S, Sakane F, Kanoh H. Translocation of diacylglycerol kinase alpha to the nuclear matrix of rat thymocytes and peripheral T-lymphocytes. FEBS Lett 1996; 393:48-52. [PMID: 8804421 DOI: 10.1016/0014-5793(96)00857-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The cytosolic alpha-diacylglycerol kinase (DGK) was translocated to and tightly associated with the nuclear matrix when rat thymocytes and peripheral T-lymphocytes were stimulated with concanavalin A or anti-T-cell receptor antibody. This translocation occurred rather slowly and was completed in 3-4 h after cell stimulation. We also detected significant accumulation of nuclear phosphatidic acid interpreted as being formed by the translocated enzyme. The enzyme translocation is not directly linked to phosphoinositide turnover and protein phosphorylation, since phorbol myristate acetate and calcium ionophore did not affect the cellular DGK alpha and since we detected no covalent modification of the enzyme molecule. Although the mechanisms underlying the enzyme translocation remain unknown, our results indicate that DGK alpha participates in nuclear phospholipid metabolism occurring at the intermediate stage of lymphocyte activation.
Collapse
Affiliation(s)
- I Wada
- Department of Biochemistry, Sapporo Medical University School of Medicine, Japan
| | | | | | | | | |
Collapse
|
18
|
Kosaka C, Sasaguri T, Ishida A, Ogata J. Cell cycle arrest in the G2 phase induced by phorbol ester and diacylglycerol in vascular endothelial cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 270:C170-8. [PMID: 8772442 DOI: 10.1152/ajpcell.1996.270.1.c170] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The role of protein kinase C (PKC) in vascular endothelial cell proliferation was investigated using human umbilical vein endothelial cells released from the G1/S border. Phorbol 12-myristate 13-acetate (PMA) caused G2 arrest because 1) when added to G2 cells, PMA inhibited subsequent cell division; 2) these growth-arrested cells did not show morphological features of mitotic cells; and 3) PMA did not interrupt mitosis in cells released from nocodazole-induced M phase arrest. 1-Oleoyl-2-acetyl-sn-glycerol (OAG) added repeatedly from G2 also inhibited mitosis. The activation of cdc2 kinase around the G2/M transition was suppressed by PMA and OAG. Although cdc2 was expressed in the presence of PMA, dephosphorylation of its tyrosine residue was inhibited by PMA. In parallel, the expression of cdc25B was suppressed by PMA. The total and the cdc2-associated amount of cyclin B were both reduced by PMA. These data suggested that the PKC pathway negatively regulates the G2/M transition and that the inhibition of cdc2 kinase by the reduction in the levels of cdc25B and cyclin B may contribute to this effect.
Collapse
Affiliation(s)
- C Kosaka
- National Cardiovascular Center Research Institute, Osaka, Japan
| | | | | | | |
Collapse
|
19
|
Szamel M, Resch K. T-cell antigen receptor-induced signal-transduction pathways--activation and function of protein kinases C in T lymphocytes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 228:1-15. [PMID: 7882988 DOI: 10.1111/j.1432-1033.1995.tb20221.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
CONTENTS. T-cell activation--Structure of the T-cell antigen receptor--Modular organisation of the T-cell antigen receptor--T-cell antigen receptor-coupled signaling pathways: Activation of protein-tyrosine kinase by the T-cell antigen receptor; Signal transduction in lymphoid cells involves several protein-tyrosine kinases in parallel; Regulation of T-cell antigen receptor signaling by the phosphoprotein phosphatase CD45--Consequences of T-cell antigen receptor-induced tyrosine phosphorylation: Activation of phosphoinositol-lipid-turnover pathways--Activation of phospholipase C-gamma-1: p59fyn or p56lck?--G-protein motif of CD3-gamma: relevance for signal transduction--Association of lipid kinase with the T-cell antigen receptor--Intracellular signaling by phospholipid metabolites and calcium: activation of protein kinase C--Protein kinase C isoenzymes--Heterogenity of protein kinase C and mode of activation--Phospholipid-derived mediators in activation of protein kinase C in T-cells--Role of phospholipase D metabolites in activation of protein kinase C--Polyunsaturated fatty acids and lysophosphatidylcholine as activators of protein kinase C--Potein kinase C and p21ras function in interdependent and distinct signaling pathways during T-cell activation--Raf-1 kinase: regulator or target of protein kinase C?--Summary and perspectives.
Collapse
Affiliation(s)
- M Szamel
- Institute of Molecular Pharmacology, Medical School Hannover, Germany
| | | |
Collapse
|
20
|
Drayer AL, van Haastert PJ. Transmembrane signalling in eukaryotes: a comparison between higher and lower eukaryotes. PLANT MOLECULAR BIOLOGY 1994; 26:1239-1270. [PMID: 7858189 DOI: 10.1007/bf00016473] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- A L Drayer
- Department of Biochemistry, University of Groningen, The Netherlands
| | | |
Collapse
|
21
|
Lee MW, Severson DL. Signal transduction in vascular smooth muscle: diacylglycerol second messengers and PKC action. THE AMERICAN JOURNAL OF PHYSIOLOGY 1994; 267:C659-78. [PMID: 7943196 DOI: 10.1152/ajpcell.1994.267.3.c659] [Citation(s) in RCA: 170] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Agonist-stimulated phospholipid turnover can generate diacylglycerol (DAG), an intracellular second messenger that activates protein kinase C (PKC). DAG can be produced from the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) by a phosphoinositide-specific phospholipase C and by the degradation of phosphatidylcholine (PC) by a phospholipase C or the concerted actions of phospholipase D and phosphatidate phosphohydrolase. In vascular smooth muscle, agonist-stimulated DAG accumulation is biphasic; PIP2 hydrolysis produces a transient increase in DAG, which is followed by a sustained phase of DAG accumulation from PC degradation. Metabolism of DAG attenuates PKC activation and thus results in signal termination. The metabolic fates for DAG include 1) ATP-dependent phosphorylation to form phosphatidic acid (DAG kinase), 2) hydrolysis to release fatty acids and glycerol (DAG and monoacylglycerol lipases), 3) synthesis of triacylglycerol (DAG acyltransferase), and 4) synthesis of PC (choline phosphotransferase). Hydrolysis through the lipase pathway is the predominant metabolic fate of DAG in vascular smooth muscle. Activation of PKC in vascular smooth muscle modulates agonist-stimulated phospholipid turnover, produces an increase in contractile force, and regulates cell growth and proliferation. Further research is required to investigate cross talk between signal transduction mechanisms involving lipid second messengers. In addition, spatial considerations such as nuclear PKC activation and the influence of diradylglycerol generation on the duration of PKC activation are important issues.
Collapse
Affiliation(s)
- M W Lee
- Medical Research Council Signal Transduction Group, Faculty of Medicine, University of Calgary, Alberta, Canada
| | | |
Collapse
|
22
|
Saxon ML, Zhao X, Black JD. Activation of protein kinase C isozymes is associated with post-mitotic events in intestinal epithelial cells in situ. J Biophys Biochem Cytol 1994; 126:747-63. [PMID: 8045938 PMCID: PMC2120146 DOI: 10.1083/jcb.126.3.747] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The mechanisms underlying control of cell growth and differentiation in epithelial tissues are poorly understood. Protein kinase C (PKC) isozymes, members of a large family of serine/threonine kinases of fundamental importance in signal transduction, have been increasingly implicated in the regulation of cell growth, differentiation, and function. Using the rat intestinal epithelium as a model system, we have examined PKC-specific activity as well as individual PKC isozyme expression and distribution (i.e., activation status) in epithelial cells in situ. Increased PKC activity was detected in differentiating and functional cells relative to immature proliferating crypt cells. Immunofluorescence and Western blot analysis using a panel of isozyme-specific antibodies revealed that PKC alpha, beta II, delta, epsilon, and zeta are expressed in rat intestinal epithelial cells and exhibit distinct subcellular distribution patterns along the crypt-villus unit. The combined morphological and biochemical approach used permitted analysis of the activation status of specific PKC isozymes at the individual cell level. These studies showed that marked changes in membrane association and level of expression for PKC alpha, beta II, delta, and zeta occur as cells cease division in the mid-crypt region and begin differentiation. Additional changes in PKC activation status are observed with acquisition of mature function on the villus. These studies clearly demonstrate naturally occurring alterations in PKC isozyme activation status at the individual cell level within the context of a developing tissue. Direct activation of PKC in an immature intestinal crypt cell line was shown to result in growth inhibition and coincident translocation of PKC alpha from the cytosolic to the particulate subcellular fraction, paralleling observations made in situ and providing further support for a role of intestinal PKC isozymes in post-mitotic events. PKC isozymes were also found to be tightly associated with cytoskeletal elements, suggesting participation in control of the structural organization of the enterocyte. Taken together, the results presented strongly suggest an involvement of PKC isoforms in cellular processes related to growth cessation, differentiation, and function of intestinal epithelial cells in situ.
Collapse
Affiliation(s)
- M L Saxon
- Department of Experimental Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | | | | |
Collapse
|
23
|
Nakayama I, Kawahara Y, Tsuda T, Okuda M, Yokoyama M. Angiotensin II inhibits cytokine-stimulated inducible nitric oxide synthase expression in vascular smooth muscle cells. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)78171-x] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
24
|
Allan CJ, Exton JH. Quantification of inositol phospholipid breakdown in isolated rat hepatocytes. Biochem J 1993; 290 ( Pt 3):865-72. [PMID: 8384449 PMCID: PMC1132361 DOI: 10.1042/bj2900865] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The hydrolysis of inositol phospholipids induced by vasopressin in hepatocytes during 60 min was quantified chemically. There was a large release of myo-inositol which was abolished by Li+, indicating that it was derived from inositol phosphates and not from phospholipase D action on PtdIns. There was also a large release of inositol phosphates which was increased approx. 2-fold by Li+ at 30 min, but then remained constant, suggesting that inositol phospholipid breakdown declined substantially beyond this time. In cells prelabelled with myo-[3H]inositol and treated with Li+, [3H]PtdIns(4,5)P2 decreased maximally (50%) at 15 s and then recovered to a level at 5 min that was maintained at 25% below control for 40 min. [3H]PtdIns4P and [3H]PtdIns showed slower decreases to approx. 30% below control at 15 min, but with no further changes. Labelled Ins(1,4,5)P3 and Ins(1,3,4)P3 showed 2-4-fold increases within 30 s and then declined to values that were maintained at a constant level above the control, except for [3H]Ins(1,3,4)P3, which showed a second increase. [3H]Ins(1,4)P2 showed a very large increase over 10 min, whereas [3H]Ins4P and [3H]Ins1P showed little change before 6 and 15 min respectively. The total [3H]inositol phosphates showed little further increase after 20 min. These data are consistent with a rapid, but not sustained, hydrolysis of PtdIns-(4,5)P2, but not of PtdIns, by phospholipase C, but do not exclude PtdIns4P as a substrate. Phosphatidate was rapidly increased by vasopressin, whereas diacylglycerol was increased after a 1-2 min lag. Both were maintained at levels 2-3-fold above control for 60 min. The vasopressin-induced increase in inositol phosphates plus myo-inositol (approx. 120 nmol/100 mg) was greater than the increase in diacylglycerol plus phosphatidate (approx. 60 nmol/100 mg) between 10 and 40 min. This indicates that there was substantial further metabolism of these lipids. Addition of 75 mM ethanol resulted in rapid production of phosphatidylethanol in response to vasopressin and a 35% reduction in phosphatidate, but no decrease in diacylglycerol. In summary, the results indicate that inositol phospholipid hydrolysis by phospholipase C can account for most of the diacylglycerol and phosphatidate that accumulate during 60 min of vasopressin action, but that these phospholipids are probably not the major source of the phosphatidate that is formed during the first 2 min by phospholipase D, or of the diacylglycerol and phosphatidate that are formed beyond 30 min.
Collapse
Affiliation(s)
- C J Allan
- Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, TN 37232
| | | |
Collapse
|
25
|
Florin-Christensen J, Florin-Christensen M, Delfino JM, Rasmussen H. New patterns of diacylglycerol metabolism in intact cells. Biochem J 1993; 289 ( Pt 3):783-8. [PMID: 8435076 PMCID: PMC1132244 DOI: 10.1042/bj2890783] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The metabolism of di[1-14C]octanoylglycerol metabolism was examined in four cell lines: NIH 3T3 fibroblasts, BHK cells, Pam 212 keratinocytes and WEHI 3BD+ cells. We found the direct conversion of 1,2-di[1-14C]octanoyl-sn-glycerol ([14C]diC8) into dioctanoylphosphatidylcholine and dioctanoylacylglycerol, but no formation of phosphatidylinositol. The [14C]diC8 also underwent lipolytic breakdown. In contrast, 1-[1-14C]oleoyl-2-acetyl-sn-glycerol was metabolized exclusively by lipolysis. Our findings support a new scheme for the metabolic termination of diacylglycerol signals.
Collapse
|
26
|
Asaoka Y, Yoshida K, Sasaki Y, Nishizuka Y, Murakami M, Kudo I, Inoue K. Possible role of mammalian secretory group II phospholipase A2 in T-lymphocyte activation: implication in propagation of inflammatory reaction. Proc Natl Acad Sci U S A 1993; 90:716-9. [PMID: 8421710 PMCID: PMC45736 DOI: 10.1073/pnas.90.2.716] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Both 2-lysophosphatidylcholine and cis-unsaturated fatty acids were previously shown to intensify agonist-induced cellular responses by enhancing the diacylglycerol-dependent activation of protein kinase C. Consistent with these observations, extracellular, secretory group II phospholipase A2, when added directly to human resting T lymphocytes, greatly potentiates their activation that was induced by a membrane-permeant diacylglycerol and ionomycin, as determined by the expression of the alpha subunit of the interleukin 2 receptor and thymidine incorporation into DNA. Diacylglycerol and ionomycin were essential for this cellular response, and phospholipase A2 alone showed no effect. The amount of 2-lysophosphatidylcholine produced in these cells by the exogenous phospholipase A2 was greatly increased in the presence of diacylglycerol and ionomycin, suggesting that the membrane phospholipids became susceptible to the phospholipase A2 when protein kinase C was activated. The results suggest that phospholipase A2 secreted into inflammatory sites plays a role in the propagation of cellular responses. Protein kinase C may function in the hydrolysis of membrane phospholipids by the exogenous phospholipase A2, and the products of this phospholipid hydrolysis enhance agonist-induced protein kinase C activation, thereby intensifying cellular responses.
Collapse
Affiliation(s)
- Y Asaoka
- Biosignal Research Center, Kobe University, Japan
| | | | | | | | | | | | | |
Collapse
|
27
|
Robinson AT, Miller N, Alexander DR. CD3 antigen-mediated calcium signals and protein kinase C activation are higher in CD45R0+ than in CD45RA+ human T lymphocyte subsets. Eur J Immunol 1993; 23:61-8. [PMID: 8419189 DOI: 10.1002/eji.1830230111] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
T lymphocytes may be separated into subsets according to their expression of CD45 isoforms. The CD45R0+ T cell subset has been reported to proliferate in response to recall antigen and to mitogenic mAb to a much greater extent than the CD45RA+ subset. This difference could be due to more efficient coupling of the T cell antigen receptor complex to mitogenic signaling pathways. To investigate this possibility, CD3 antigen-induced calcium signals, diacylglycerol (DAG) production and protein kinase C (PKC) activation levels were compared in CD45RA+ and CD45R0+ human T lymphocyte subsets derived from peripheral blood. The mean CD3-induced rise in intracellular calcium was 80% greater in CD45R0+ than in CD45RA+ cells. Basal DAG levels in CD45R0+ cells were found to be, on average, 60% higher than in CD45RA+ cells (p = 0.002), but the CD3-induced production of DAG over background was not different in the two subsets (p = 0.4). Basal PKC activity, and CD3-induced PKC activation levels over background, were found to be 50% and 140% higher, respectively, in CD45R0+ cells than in CD45RA+ cells (p = 0.015 and 0.023). The CD45R0+ subset contained a higher proportion of cells expressing activation markers, such as CD25, CD71 and major histocompatibility complex class II, when compared to the CD45RA+ subset. Our results suggest that the elevated basal DAG levels observed in the CD45R0+ subset may reflect the recent activation of these cells. Both the higher basal DAG and CD3-induced elevation in intracellular calcium observed in the CD45R0+ cells may contribute to the greater PKC activation signals triggered by CD3 mAb in this subset. These findings elucidate the greater response of CD45R0+ T cells to mitogenic stimuli compared to CD45RA+ cells.
Collapse
Affiliation(s)
- A T Robinson
- Department of Immunology, Institute of Animal Physiology & Genetics Research, Babraham, Cambridge
| | | | | |
Collapse
|
28
|
Nishizuka Y. Intracellular signaling by hydrolysis of phospholipids and activation of protein kinase C. Science 1992; 258:607-14. [PMID: 1411571 DOI: 10.1126/science.1411571] [Citation(s) in RCA: 3481] [Impact Index Per Article: 108.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Hydrolysis of inositol phospholipids by phospholipase C is initiated by either receptor stimulation or opening of Ca2+ channels. This was once thought to be the sole mechanism to produce the diacylglycerol that links extracellular signals to intracellular events through activation of protein kinase C. It is becoming clear that agonist-induced hydrolysis of other membrane phospholipids, particularly choline phospholipids, by phospholipase D and phospholipase A2 may also take part in cell signaling. The products of hydrolysis of these phospholipids may enhance and prolong the activation of protein kinase C. Such prolonged activation of protein kinase C is essential for long-term cellular responses such as cell proliferation and differentiation.
Collapse
Affiliation(s)
- Y Nishizuka
- Department of Biochemistry, Kobe University School of Medicine, Japan
| |
Collapse
|
29
|
Asaoka Y, Oka M, Yoshida K, Sasaki Y, Nishizuka Y. Role of lysophosphatidylcholine in T-lymphocyte activation: involvement of phospholipase A2 in signal transduction through protein kinase C. Proc Natl Acad Sci U S A 1992; 89:6447-51. [PMID: 1631142 PMCID: PMC49518 DOI: 10.1073/pnas.89.14.6447] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
2-Lysophosphatidylcholine (lysoPtdCho), a product of the hydrolysis of phosphatidylcholine catalyzed by phospholipase A2, greatly potentiates the activation of human resting T lymphocytes that is induced by a membrane-permeant diacylglycerol plus a calcium ionophore, as determined by the expression of the alpha subunit of the interleukin 2 receptor and thymidine incorporation into DNA. LysoPtdCho per se is inactive unless both diacylglycerol and a calcium ionophore are present. This effect of lysoPtdCho is also observed when diacylglycerol is replaced by a tumor-promoting phorbol ester. Other lysophosphatides including lysophosphatidylserine, lysophosphatidylinositol, and lysophosphatidic acid are inert except for lysophosphatidylethanolamine, which is far less effective than lysoPtdCho. Tracer experiments with radioactive choline indicate that, when T lymphocytes are stimulated with an antigenic signal, lysoPtdCho is indeed produced in a time-dependent fashion, although the concentration of this lysophospholipid accumulated remains to be quantitated. It suggests that phospholipase A2 is directly involved in the signal transduction pathway through protein kinase C to induce long-term cellular responses.
Collapse
Affiliation(s)
- Y Asaoka
- Biosignal Research Center, Kobe University, Japan
| | | | | | | | | |
Collapse
|
30
|
Yoshida K, Asaoka Y, Nishizuka Y. Platelet activation by simultaneous actions of diacylglycerol and unsaturated fatty acids. Proc Natl Acad Sci U S A 1992; 89:6443-6. [PMID: 1631141 PMCID: PMC49517 DOI: 10.1073/pnas.89.14.6443] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Several cis-unsaturated fatty acids such as oleic, linoleic, linolenic, eicosapentaenoic, and docosahexaenoic acids added directly to intact human platelets greatly enhance protein kinase C activation as judged by the phosphorylation of its specific endogenous substrate, a 47-kDa protein. This enhancement absolutely requires the presence of a membrane-permeant diacylglycerol, 1,2-dioctanoylglycerol, or a tumor-promoting phorbol ester, phorbol 12-myristate 13-acetate. In the presence of ionomycin and either 1,2-dioctanoylglycerol or phorbol 12-myristate 13-acetate, the release of serotonin from the platelets is also remarkably increased by cis-unsaturated fatty acids. The effect of these fatty acids is observed at concentrations less than 50 microM. Saturated fatty acids and trans-unsaturated fatty acids are inactive. Titration of ionomycin to induce a release reaction and measurement of the intracellular Ca2+ level by the fura-2 procedure indicate that cis-unsaturated fatty acids increase an apparent sensitivity of the platelet response to Ca2+. The results suggest that cis-unsaturated fatty acids, which are presumably produced from phosphatidylcholine by signal-dependent activation of phospholipase A2, may take part directly in cell signaling through the protein kinase C pathway.
Collapse
Affiliation(s)
- K Yoshida
- Department of Biochemistry, Kobe University School of Medicine, Japan
| | | | | |
Collapse
|
31
|
Ogita K, Miyamoto S, Yamaguchi K, Koide H, Fujisawa N, Kikkawa U, Sahara S, Fukami Y, Nishizuka Y. Isolation and characterization of delta-subspecies of protein kinase C from rat brain. Proc Natl Acad Sci U S A 1992; 89:1592-6. [PMID: 1542650 PMCID: PMC48498 DOI: 10.1073/pnas.89.5.1592] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The delta-subspecies of protein kinase C (delta PKC) was purified to near homogeneity from the Triton X-100 extract of the rat brain particulate fraction by successive chromatographies on S-Sepharose fast flow, phenyl 5PW, heparin 5PW, hydroxyapatite, and Mono Q columns. The purified enzyme was a doublet with molecular masses of 78 and 76 kDa on SDS/PAGE. The doublet proteins were separated partially by Mono Q column chromatography; both were recognized by the antibodies raised against synthetic oligopeptides, parts of the deduced amino acid sequence of the rat delta PKC. Protein phosphatase 2A treatment suggested that the 78-kDa protein was a phosphorylated form of the 76-kDa protein. To confirm the structural and genetic identity of the doublet proteins, delta PKC was expressed in COS 7 cells by transfecting its cDNA-constructed plasmid and was purified for comparison. This recombinant enzyme was also a doublet. The enzymes isolated from the brain and COS 7 cells showed identical reactivities with delta PKC-specific antibodies, chromatographic behaviors, and V8 protease peptide mappings. In addition, these two enzyme preparations were indistinguishable from each other in their responses to phosphatidylserine, diacylglycerol, phorbol esters, free fatty acids, Ca2+, and enzyme inhibitors. Comparison was also made between the enzymologic properties of delta PKC and alpha PKC, which were distinctly different from each other.
Collapse
Affiliation(s)
- K Ogita
- Department of Biochemistry, Kobe University School of Medicine, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Aihara H, Asaoka Y, Yoshida K, Nishizuka Y. Sustained activation of protein kinase C is essential to HL-60 cell differentiation to macrophage. Proc Natl Acad Sci U S A 1991; 88:11062-6. [PMID: 1763021 PMCID: PMC53073 DOI: 10.1073/pnas.88.24.11062] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Although a single dose of phorbol 12-myristate 13-acetate (PMA) allowed HL-60 cells to differentiate to macrophages, a single dose of membrane-permeant diacylglycerol (DAG), 1,2-dioctanoylglycerol (1,2-DiC8), was normally insufficient to differentiate these cells. These cells metabolized 1,2-DiC8 very rapidly, and 1,2-DiC8 available to protein kinase C (PKC) activation was removed from the incubation medium at a rate proportional to cell density. However, increasing the duration of exposure of HL-60 cells to this DAG either by its repeated addition or by decreasing the cell density greatly enhanced their differentiation to macrophages as measured by CD11b expression. During this differentiation induced by DAG, neither measurable translocation nor depletion (down-regulation) of PKC was observed. When the cells were exposed to PMA, on the other hand, some PKC subspecies were instantaneously translocated to membranes and subsequently disappeared very quickly, whereas the alpha-subspecies was decreased to the level of approximately 60% of the resting cell, but thereafter its activity was maintained at a nearly constant level in membranes. After approximately 4 hr, the PKC subspecies, once depleted, reappeared gradually in the membrane fraction. The results suggest that sustained activation of PKC is essential to differentiation of HL-60 cells to macrophages, and depletion of the enzyme is not needed. Perhaps translocation of PKC represents an extreme state of the active form of the enzyme, which may result from PMA action, and the alpha-subspecies presumably plays a key role in HL-60 cell differentiation.
Collapse
Affiliation(s)
- H Aihara
- Department of Biochemistry, Kobe University School of Medicine, Japan
| | | | | | | |
Collapse
|