1
|
Antollini SS, Barrantes FJ. Fatty Acid Regulation of Voltage- and Ligand-Gated Ion Channel Function. Front Physiol 2016; 7:573. [PMID: 27965583 PMCID: PMC5124694 DOI: 10.3389/fphys.2016.00573] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 11/09/2016] [Indexed: 12/25/2022] Open
Abstract
Free fatty acids (FFA) are essential components of the cell, where they play a key role in lipid and carbohydrate metabolism, and most particularly in cell membranes, where they are central actors in shaping the physicochemical properties of the lipid bilayer and the cellular adaptation to the environment. FFA are continuously being produced and degraded, and a feedback regulatory function has been attributed to their turnover. The massive increase observed under some pathological conditions, especially in brain, has been interpreted as a protective mechanism possibly operative on ion channels, which in some cases is of stimulatory nature and in other cases inhibitory. Here we discuss the correlation between the structure of FFA and their ability to modulate protein function, evaluating the influence of saturation/unsaturation, number of double bonds, and cis vs. trans isomerism. We further focus on the mechanisms of FFA modulation operating on voltage-gated and ligand-gated ion channel function, contrasting the still conflicting evidence on direct vs. indirect mechanisms of action.
Collapse
Affiliation(s)
- Silvia S Antollini
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (CONICET-UNS)Bahía Blanca, Argentina; Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del SurBahía Blanca, Argentina
| | | |
Collapse
|
2
|
Abstract
Diabetes mellitus is responsible for nearly 10% of fetal anomalies in diabetic pregnancies. Although aggressive perinatal care and glycemic control are available in developed countries, the birth defect rate in diabetic pregnancies remains higher than that in the general population. Major cellular activities (ie, proliferation and apoptosis) and intracellular metabolic conditions (ie, nitrosative, oxidative, and endoplasmic reticulum stress) have been shown to be associated with diabetic embryopathy using animal models. Translating advances made in animal studies into clinical applications in humans requires collaborative efforts across the basic research, preclinical, and clinical communities.
Collapse
Affiliation(s)
- Zhiyong Zhao
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | | |
Collapse
|
3
|
Singh TU, Choudhury S, Parida S, Maruti BS, Mishra SK. Arachidonic acid inhibits Na⁺-K⁺-ATPase via cytochrome P-450, lipoxygenase and protein kinase C-dependent pathways in sheep pulmonary artery. Vascul Pharmacol 2011; 56:84-90. [PMID: 22155164 DOI: 10.1016/j.vph.2011.11.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 09/04/2011] [Accepted: 11/28/2011] [Indexed: 11/16/2022]
Abstract
The purpose of the study was to examine whether arachidonic acid inhibits vascular Na(+)-K(+)-ATPase in pulmonary vasculature and if so, what are the mechanisms involved. Functional Na(+)-K(+)-ATPase activity was studied in terms of K(+)-induced relaxation in sheep pulmonary arterial rings contracted with K(+)-free solution and 5-HT. Arachidonic acid (10-100 μM) caused concentration-dependent inhibition of KCl-induced relaxations and also increased basal arterial tone. Cytochrome P-450 inhibitor, 17-octadecynoic acid (17-ODYA) completely reversed the arachidonic acid (30 μM)-induced inhibition of KCl relaxation. Further, in the presence of HET0016, a selective blocker of 20-hydroxyeicosatetraenoic acid (20-HETE), arachidonic acid-induced inhibition of KCl relaxation was not evident. Accordingly, 20-HETE, a cytochrome P-450 metabolite of arachidonic acid, also significantly attenuated KCl-induced relaxations. Norhydihydroguaiaretic acid (NDGA), a lipoxygenase inhibitor, however, partially restored the relaxation to K(+), impaired in the presence of arachidonic acid (30 μM). On the other hand, cyclooxygenase inhibitor indomethacin failed to reverse the inhibitory effect of arachidonic acid on KCl-induced relaxation. Staurosporin, a protein kinase C inhibitor, completely reversed the inhibitory effect of arachidonic acid and 20-HETE on K(+)-induced relaxation. In conclusion, the results suggest that 20-HETE, a cytochrome P-450 metabolite of arachidonic acid has a predominant role in the inhibition of functional Na(+)-K(+)-ATPase activity in the sheep pulmonary artery, while the lipooxygenase pathway has a secondary role. It is also evident that protein kinase C is involved in the inhibition of Na(+)-K(+)-ATPase by arachidonic acid/20-HETE in sheep pulmonary artery.
Collapse
Affiliation(s)
- Thakur Uttam Singh
- Division of Pharmacology and Toxicology, Indian Veterinary Research Institute, Izatnagar-243122, Bareilly, Uttar Pradesh, India.
| | | | | | | | | |
Collapse
|
4
|
Priante G, Musacchio E, Pagnin E, Calò LA, Baggio B. Specific effect of arachidonic acid on inducible nitric oxide synthase mRNA expression in human osteoblastic cells. Clin Sci (Lond) 2005; 109:177-82. [PMID: 15801909 DOI: 10.1042/cs20040369] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A specific modulatory effect of PUFAs (polyunsaturated fatty acids) on gene expression of some cytokines involved in bone remodelling has been reported previously. In particular, although a direct action of AA (arachidonic acid) on bone cytokine gene expression has been shown in human osteoblastic cells, OA (oleic acid) and EPA (eicosapentaenoic acid) were ineffective. Since the NO (nitric oxide) system has also been shown to have an important modulatory activity on osteoblasts, osteoclasts and bone metabolism, in the present study we have investigated the effects of PUFAs on iNOS (inducible NO synthase) gene expression in a human osteoblast-like cell line. AA induced a significant increase in iNOS mRNA expression, whereas EPA and OA had no stimulatory effects but instead caused a significant inhibition of AA-induced iNOS gene expression. Blocking of the COX (cyclo-oxygenase) pathway did not inhibit AA-induced iNOS expression. AA action was inhibited instead by the addition of calphostin C and genistein, inhibitors of PKC (protein kinase C) and tyrosine kinases respectively. Experiments performed with specific anti-cytokine antibodies showed a significant decrease in iNOS expression in AA-treated osteoblastic cells, suggesting that both cytokine-dependent and -independent mechanisms account for the effects of AA on iNOS gene expression. In conclusion, our investigation clearly shows specific effects of PUFAs on iNOS expression in human osteoblast-like cells with a cytokine-dependent and -independent mechanism. These results might have clinical relevance and are of interest for understanding the reported beneficial effects of dietary PUFA manipulation on the prevention and/or treatment of primary and secondary bone disease.
Collapse
Affiliation(s)
- Giovanna Priante
- Department of Medical and Surgical Sciences, University of Padua, Padova, Italy
| | | | | | | | | |
Collapse
|
5
|
Huang X, Walker JW. Myofilament anchoring of protein kinase C-epsilon in cardiac myocytes. J Cell Sci 2004; 117:1971-8. [PMID: 15039458 DOI: 10.1242/jcs.01044] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Regulatory proteins on muscle filaments are substrates for protein kinase C (PKC) but mechanisms underlying activation and translocation of PKC to this non-membrane compartment are poorly understood. Here we demonstrate that the epsilon isoform of PKC (ϵ-PKC) activated by arachidonic acid (AA) binds reversibly to cardiac myofibrils with an EC50 of 86 nM. Binding occurred near the Z-lines giving rise to a striated staining pattern. The delta isoform of PKC (δ-PKC) did not bind to cardiac myofibrils regardless of the activator used, and the alpha isoform (α-PKC) bound only under strong activating conditions. Three established PKC anchoring proteins, filamentous actin (F-actin), the LIM domain protein Cypher-1, and the coatamer protein β′-COP were each tested for their involvement in cytoskeletal anchoring. F-actin bound ϵ-PKC selectively over δ-PKC and α-PKC, but this interaction was readily distinguishable from cardiac myofilament binding in two ways. First, the F-actin/ϵ-PKC interaction was independent of PKC activation, and second, the synthetic hexapeptide LKKQET derived from the C1 region of ϵ-PKC effectively blocked ϵ-PKC binding to F-actin, but was without effect on its binding to cardiac myofilaments. Involvement of Cypher-1 was ruled out on the basis of its absence from detergent-skinned myofibrils that bound ϵ-PKC, despite its presence in intact cardiac myocytes. The ϵ-PKC translocation inhibitor peptide EAVSLKPT reduced activated ϵ-PKC binding to cardiac myofibrils in a concentration dependent manner, suggesting that a RACK2 or a similar protein plays a role in ϵ-PKC anchoring in cardiac myofilaments.
Collapse
Affiliation(s)
- Xupei Huang
- Department of Biomedical Science, Florida Atlantic University, Boca Raton, FL 33431, USA.
| | | |
Collapse
|
6
|
Abstract
Prostaglandins have long been thought to play important roles in the mechanism of parturition. Here we review the involvement of prostaglandins in myometrial and cervical functions with emphasis on human labor and birth. In addition, the cellular sources of prostaglandins as well as their interactions with various other endocrine, paracrine and physical factors, such as oxytocin, corticotropin releasing hormone, nitric oxide, platelet activating factor, cytokines, endothelin and stretch are also addressed together with their potential role in the molecular reorganization of cervical structure associated with labor and delivery. Finally, the premier role of progesterone in pregnancy maintenance and parturition is juxtaposed with the proposed "fine-tuning", modulatory role of prostaglandins and the above listed factors in the regulation of parturition.
Collapse
Affiliation(s)
- Frank Hertelendy
- Department of Obstetrics, Gynecology and Women's Health, St. Mary's Health Center, St. Louis University, School of Medicine, St. Louis, MO 63117, USA.
| | | |
Collapse
|
7
|
Affiliation(s)
- María J T de Alaniz
- Instituto de Investigaciones Bioquímicas de La Plata, CONICET-UNLP, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, calles 60 y 120, (1900) La Plata, Argentina.
| | | |
Collapse
|
8
|
Doolan CM, Harvey BJ. A Galphas protein-coupled membrane receptor, distinct from the classical oestrogen receptor, transduces rapid effects of oestradiol on [Ca2+]i in female rat distal colon. Mol Cell Endocrinol 2003; 199:87-103. [PMID: 12581882 DOI: 10.1016/s0303-7207(02)00303-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We examined the hypothesis whether rapid non-genomic effects of oestradiol (E2) on [Ca(2+)](i) are mediated via a membrane-located oestrogen receptor (ER) and further elucidated the signalling pathways involved in rapid non-genomic effects of E2 on [Ca(2+)](i) in distal colonic crypts. Basal [Ca(2+)](i) was significantly increased, within minutes, in response to physiological concentrations of E2. Oestradiol linked to bovine serum albumin (E2-BSA), which renders the E2 membrane impermeable, rapidly increased [Ca(2+)](i) suggesting mediation by a membrane surface receptor. A classical ER is not involved however, as no inhibition of either the E2 or E2-BSA [Ca(2+)](i) response was seen in the presence of the classical ER antagonist ICI 182,780. Treatment with the Galphas inhibitor cholera toxin abolished both E2 and E2-BSA induced Ca(2+) increases. In contrast, treatment with pertussis toxin, an inhibitor of Galphai and Galphao, had no inhibitory effect. Following subsequent additions of E2 and E2-BSA, no further increases in [Ca(2+)](i) were observed, indicating receptor desensitisation. The E2-induced increase in [Ca(2+)](i) was completely abolished by the PKCdelta-specific inhibitor rottlerin, whereas Go6976, an inhibitor of Ca(2+)-sensitive PKC isoforms, was without inhibitory effect. The phospholipase A2 antagonist, quinacrine, and the COX1 inhibitor, indomethacin, abolished the E2-induced increase in [Ca(2+)](i). MAP kinase activation is not involved in rapid stimulatory effects of E2 on [Ca(2+)](i) as the specific inhibitor PD98059 did not inhibit the E2 response. These results demonstrate that rapid E2-induced stimulation of [Ca(2+)](i), in femal rat distal colonic crypts, occurs via a CTx-sensitive Galphas-coupled membrane receptor distinct from the classical ER. PKCdelta and fatty acids are involved in the E2 signalling pathway. In contrast, PKCalpha and MAP kinase are not required.
Collapse
Affiliation(s)
- Christina M Doolan
- Department of Physiology, Biosciences Institute, University College Cork, Ireland.
| | | |
Collapse
|
9
|
Bostan M, Galatiuc C, Hirt M, Constantin MC, Brasoveanu LI, Iordachescu D. Phospholipase A2 modulates respiratory burst developed by neutrophils in patients with rheumatoid arthritis. J Cell Mol Med 2003; 7:57-66. [PMID: 12767262 PMCID: PMC6740302 DOI: 10.1111/j.1582-4934.2003.tb00203.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Activated by bacterial peptides, phorbol esters, calcium ionophores and other agonists, neutrophils (PMNs) release the proinflammatory mediator, arachidonic acid (AA) via the intervention of phospholipase A(2) (PLA(2)). AA may play an essential role in activation of NADPH-oxidase, which is involved in the generation of superoxide anion by neutrophils. The present study is focused on the involvement of PLA(2) in the respiratory burst developed by PMNs isolated from patients with rheumatoid arthritis (RA). PLA(2) exists in very high levels in diseases such as rheumatoid arthritis and may cause acute inflammatory and proliferative changes in synovial structures. The respiratory burst was evaluated as superoxide anion release, using an amplified chemiluminescence method. The assays were performed using PMNs untreated or treated with different doses of stimulatory reagents (phorbol 12-myristate-13-acetate (PMA), calcium ionophore (A23187)). Our data suggested that PMA stimulated the production of superoxide anion in a dose-response manner, as compared with A23187, which did not induce a significant release of superoxide anion in PMNs-RA. The exogenous addition of AA significantly amplified the superoxide anion release by PMNs-RA stimulated with PMA and to a lesser extent, by PMNs stimulated with A23187. AA has also reversed the inhibitory effect of arachidonyl-trifluorometylketone and E-6-(bromomethylene)tetrahydro-3-(1-naphthalenyl)2H-pyran-2-one (BEL) on the superoxide anion release by PMNs-RA. In conclusion, the differential responses to these two agents suggested that different isoforms of PLA(2) were activated by A23187 or PMA, and support the idea that activation of these different PLA(2) served distinct functions of PMNs. Therefore, the inhibition of PLA(2) enzymes might be of great importance in the immunotherapy of rheumatoid arthritis.
Collapse
Affiliation(s)
- Marinela Bostan
- Center of Immunology, Stefan S. Nicolau Institute of Virology, Bucharest, Romania.
| | | | | | | | | | | |
Collapse
|
10
|
Clarke AL, Petrou S, Walsh JV, Singer JJ. Modulation of BK(Ca) channel activity by fatty acids: structural requirements and mechanism of action. Am J Physiol Cell Physiol 2002; 283:C1441-53. [PMID: 12372805 DOI: 10.1152/ajpcell.00035.2002] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To determine the mechanism of fatty acid modulation of rabbit pulmonary artery large-conductance Ca2+ -activated K+ (BK(Ca)) channel activity, we studied effects of fatty acids and other lipids on channel activity in excised patches with patch-clamp techniques. The structural features of the fatty acid required to increase BK(Ca) channel activity (or average number of open channels, NP(o)) were identified to be the negatively charged head group and a sufficiently long (C > 8) carbon chain. Positively charged lipids like sphingosine, which have a sufficiently long alkyl chain (C >or= 8), produced a decrease in NP(o). Neutral and short-chain lipids did not alter NP(o). Screening of membrane surface charge with high-ionic-strength bathing solutions (330 mM K+ or 130 mM K+, 300 mM Na+) did not alter the modulation of the BK(Ca) channel NP(o) by fatty acids and other charged lipids, indicating that channel modulation is unlikely to be due to an alteration of the membrane electric field or the attraction of local counterions to the channel. Fatty acids and other negatively charged lipids were able to modulate BK(Ca) channel activity in bathing solutions containing 0 mM Ca2+, 20 mM EGTA, suggesting that calcium is not required for this modulation. Together, these results indicate that modulation of BK(Ca) channels by fatty acids and other charged lipids most likely occurs by their direct interaction with the channel protein itself or with some other channel-associated component.
Collapse
Affiliation(s)
- Alison L Clarke
- Department of Physiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
| | | | | | | |
Collapse
|
11
|
Werz O, Szellas D, Steinhilber D, Rådmark O. Arachidonic acid promotes phosphorylation of 5-lipoxygenase at Ser-271 by MAPK-activated protein kinase 2 (MK2). J Biol Chem 2002; 277:14793-800. [PMID: 11844797 DOI: 10.1074/jbc.m111945200] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We demonstrated previously that 5-lipoxygenase (5-LO), a key enzyme in leukotriene biosynthesis, can be phosphorylated by p38 MAPK-regulated MAPKAP kinases (MKs). Here we show that mutation of Ser-271 to Ala in 5-LO abolished MK2 catalyzed phosphorylation and clearly reduced phosphorylation by kinases prepared from stimulated polymorphonuclear leukocytes and Mono Mac 6 cells. Compared with heat shock protein 27 (Hsp-27), 5-LO was a weak substrate for MK2. However, the addition of unsaturated fatty acids (i.e. arachidonate 1-50 microm) up-regulated phosphorylation of 5-LO, but not of Hsp-27, by active MK2 in vitro, resulting in a similar phosphorylation as for Hsp-27. 5-LO was phosphorylated also by other serine/threonine kinases recognizing the motif Arg-Xaa-Xaa-Ser (protein kinase A, Ca(2+)/calmodulin-dependent kinase II), but these activities were not increased by fatty acids. HeLa cells expressing wild type 5-LO or S271A-5-LO, showed prominent 5-LO activity when incubated with Ca(2+)-ionophore plus arachidonate. However, when stimulated with only exogenous arachidonic acid, activity for the S271A mutant was significantly lower as compared with wild type 5-LO. It appears that phosphorylation at Ser-271 is more important for 5-LO activity induced by a stimulus that does not prominently increase intracellular Ca(2+) and that arachidonic acid stimulates leukotriene biosynthesis also by promoting this MK2-catalyzed phosphorylation.
Collapse
Affiliation(s)
- Oliver Werz
- Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry II, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | | | | | | |
Collapse
|
12
|
Tsimaratos M, Coste TC, Djemli-Shipkolye A, Vague P, Pieroni G, Raccah D. Gamma-linolenic acid restores renal medullary thick ascending limb Na(+),K(+)-ATPase activity in diabetic rats. J Nutr 2001; 131:3160-5. [PMID: 11739860 DOI: 10.1093/jn/131.12.3160] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In diabetes, the activity of Delta-6 desaturase, which converts linoleic acid (LA) into gamma-linolenic acid (GLA), the first step of arachidonic acid (AA) synthesis, is decreased, leading to alterations in membrane phospholipid composition. On the other hand, 12 wk after the onset of diabetes, Na(+),K(+)-ATPase activity is reduced in many organs, including the kidney. The medullary thick ascending limb (MTAL) reduced Na(+),K(+)-ATPase activity, whereas the sodium load secondary to glomerular hyperfiltration was increased. The aim of our study was to examine whether the changes in membrane fatty acid composition resulting from the inhibition of Delta-6 desaturase may be involved in the decreased Na(+),K(+)-ATPase activity observed in the outer MTAL after 12 wk of diabetes. GLA is a fatty acid that by-passes the Delta-6 desaturase step. We measured the membrane fatty acid composition and the Na(+),K(+)-ATPase activity in the renal outer medulla of control and streptozotocin (STZ)-induced diabetic rats 12 wk after the induction of diabetes. Measurements were performed after supplementation of control rats with sunflower oil (SO) or GLA for 12 wk, and supplementation of 12 wk diabetic rats with SO for 12 wk or with GLA for 6 or 12 wk. Supplementation with GLA not only prevented the decrease in Na(+),K(+)-ATPase activity observed after 12 wk of diabetes but also time dependently stimulated Na(+),K(+)-ATPase activity in the outer medulla. The changes in Na(+),K(+)-ATPase activity were related to parallel changes in the amount of Na(+),K(+)-ATPase alpha(1) subunit protein. In addition, in diabetic rats only, Na(+),K(+)-ATPase activity was positively correlated with the amount of AA present in cell membranes (r = 0.92, P < 0.05). Our results indicate that nutritional GLA supplementation increases Na(+),K(+)-ATPase activity and expression in diabetic rats. In addition, the positive correlation between AA content and Na(+),K(+)-ATPase activity suggests that in diabetic rats, alterations in membrane fatty acid composition contribute to the decreased Na(+),K(+)-ATPase activity in outer medulla.
Collapse
Affiliation(s)
- M Tsimaratos
- UPRES EA 21-93, Faculté de Médecine Timone, 13385 Marseille cedex 05, France.
| | | | | | | | | | | |
Collapse
|
13
|
Pi Y, Walker JW. Diacylglycerol and fatty acids synergistically increase cardiomyocyte contraction via activation of PKC. Am J Physiol Heart Circ Physiol 2000; 279:H26-34. [PMID: 10899038 DOI: 10.1152/ajpheart.2000.279.1.h26] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lipid signaling pathways are thought to play a prominent role in transducing extracellular signals into contractile responses in cardiac muscle. Two putative lipid messengers, diacyglycerol and arachidonic acid, can be generated via distinct phospholipases in separate signaling pathways, but certain stimuli cause them to be elevated in parallel. We tested the hypothesis that these lipids function as comessengers in ventricular myocytes by activating protein kinase C (PKC). In previous work, we demonstrated that the diacylglycerol analog dioctanoylglycerol (diC(8)) can be stimulatory or inhibitory toward myocyte twitches depending on how it is applied. Here we report that arachidonic acid and other cis-unsaturated fatty acids (UFA), at concentrations too low for direct effects, synergistically enhance the stimulatory effects of diC(8) and convert inhibitory effects of diC(8) into stimulation of myocyte twitches. Intracellular Ca(2+) transients changed in parallel with twitch amplitude, suggesting regulation of Ca(2+) homeostasis by these lipids. cis-UFA also interacted synergistically with the PKC activator phorbol 12-myristate 13-acetate to promote positive inotropic responses. Responses were blocked by the PKC antagonists chelerythrine chloride, bisindolylmaleimide, and Gö-6976. DiC(8) and arachidonic acid also synergistically translocated PKC-epsilon and PKC-alpha in intact myocytes. We propose that PKC integrates diacylglycerol and cis-UFA signals in the heart, resulting in preferential activation of positive inotropic mechanisms.
Collapse
Affiliation(s)
- Y Pi
- Department of Physiology, University of Wisconsin, Madison, Wisconsin 53706, USA
| | | |
Collapse
|
14
|
|
15
|
Jiang WG, Bryce RP, Horrobin DF. Essential fatty acids: molecular and cellular basis of their anti-cancer action and clinical implications. Crit Rev Oncol Hematol 1998; 27:179-209. [PMID: 9649932 DOI: 10.1016/s1040-8428(98)00003-1] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- W G Jiang
- University Department of Surgery, University of Wales College of Medicine, Cardiff, UK.
| | | | | |
Collapse
|
16
|
Peri KG, Almazan G, Varma DR, Chemtob S. A role for protein kinase C alpha in stimulation of prostaglandin G/H synthase-2 transcription by 14,15-epoxyeicosatrienoic acid. Biochem Biophys Res Commun 1998; 244:96-101. [PMID: 9514882 DOI: 10.1006/bbrc.1998.8215] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Arachidonic acid, but not eicosapentaenoic acid, increased prostaglandin G/H endoperoxide synthase-2 transcription in cultured intestinal epithelial cells. This stimulatory effect on PGHS-2 synthesis was prevented by an AA utilization inhibitor, eicosatetraynoic acid. Specific inhibitors of the cyclooxygenase or the lipoxygenase pathways of AA metabolism did not prevent AA-mediated induction of PGHS-2 synthesis; however, the involvement of cytochrome P450 monoxygenases (CYP450) was indicated as several CYP450 blockers, ketoconazole, miconazole, and metyrapone, inhibited the induction of PGHS-2 mRNA synthesis by AA. This blockade by CYP450 inhibitors could be overcome by the addition of the AA epoxygenase metabolite 14,15-epoxyeicosatrienoic acid (14,15-EET); other EET regio-isomers were unable to elevate PGHS-2 mRNA level. Blockade of protein kinase C with a specific inhibitor, bisindolyl maleimide-1, or translational inhibition of protein kinase C alpha by antisense oligonucleotides reduced PGHS-2 transcription, suggesting the involvement of protein kinase C alpha in the signal transduction pathway.
Collapse
Affiliation(s)
- K G Peri
- Research Center, Ste. Justine Hospital, Catherine, Montreal, Canada
| | | | | | | |
Collapse
|
17
|
Tithof PK, Peters-Golden M, Ganey PE. Distinct Phospholipases A2 Regulate the Release of Arachidonic Acid for Eicosanoid Production and Superoxide Anion Generation in Neutrophils. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.160.2.953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Arachidonic acid (AA) released from membrane phospholipids by phospholipase A2 (PLA2) is important as a substrate for eicosanoid formation and as a second messenger for superoxide anion (O2−) generation in neutrophils. Different isoforms of PLA2 in neutrophils might mobilize AA for different functions. To test this possibility, we sought to characterize the PLA2s that are activated by the neutrophil stimuli, Aroclor 1242, a mixture of polychlorinated biphenyls, and A23187, a calcium ionophore. Both Aroclor 1242 and A23187 caused release of [3H]AA; however, O2− production was seen only in response to Aroclor 1242. Eicosanoids accounted for >85% of the radioactivity recovered in the supernatant of A23187-stimulated cells but <20% of the radioactivity recovered from cells exposed to Aroclor 1242. Omission or chelation of calcium abolished A23187-induced AA release, but did not alter AA release in Aroclor 1242-stimulated neutrophils. AA release and O2− production in response to Aroclor 1242 were inhibited by bromoenol lactone (BEL), an inhibitor of calcium-independent PLA2. BEL, however, did not alter A23187-induced release of AA. Cell-free assays demonstrated both calcium-dependent and calcium-independent PLA2 activity. Calcium-independent activity was inhibited >80% by BEL, whereas calcium-dependent activity was inhibited <5%. Furthermore, calcium-independent, but not calcium-dependent, PLA2 activity was significantly enhanced by Aroclor 1242. These data suggest that Aroclor 1242 and A23187 activate distinct isoforms of PLA2 that are linked to different functions: Aroclor 1242 activates a calcium-independent PLA2 that releases AA for the generation of O2−, and A23187 activates a calcium-dependent PLA2 that mobilizes AA for eicosanoid production.
Collapse
Affiliation(s)
| | - Marc Peters-Golden
- ‡Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Patricia E. Ganey
- *Pharmacology and Toxicology, and
- †Medicine and Institute for Environmental Toxicology, Michigan State University, East Lansing, MI 48824; and
| |
Collapse
|
18
|
Lange A, Gebremedhin D, Narayanan J, Harder D. 20-Hydroxyeicosatetraenoic acid-induced vasoconstriction and inhibition of potassium current in cerebral vascular smooth muscle is dependent on activation of protein kinase C. J Biol Chem 1997; 272:27345-52. [PMID: 9341185 DOI: 10.1074/jbc.272.43.27345] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
20-Hydroxyeicosatetraenoic acid (20-HETE), a cytochrome P450 metabolite of arachidonic acid, is a potent vasoconstrictor, and has been implicated in the myogenic activation of renal and cerebral arteries. We examined the role of protein kinase C (PKC) in the signal transduction pathway by which 20-HETE induces vasoconstriction and inhibition of whole-cell K+ current in cat cerebral vascular smooth muscle. 20-HETE induced a concentration-dependent constriction in isolated pressurized cat middle cerebral arteries (-29 +/- 8% at 1 microM). However, in the presence of an N-myristoylated PKC pseudosubstrate inhibitor peptide (MyrPsiPKC-I(19-27)), 20-HETE induced a concentration-dependent vasodilation (26 +/- 4% at 1 microM). In whole-cell voltage clamp studies, application of 20-HETE inhibited whole-cell K+ current recorded in cat cerebral vascular smooth muscle cells, an effect that was attenuated by MyrPsiPKC-I(19-27). Further evidence for the role of PKC activation in response to 20-HETE is the finding that 20-HETE increased the phosphorylation of myristoylated, alanine-rich PKC substrate in cultured cat cerebral vascular smooth muscle cells in a concentration- and PKC-dependent manner. These data provide evidence that PKC is an integral part of the signal transduction pathway by which 20-HETE elicits vasoconstriction of cerebral arteries and inhibition of whole-cell K+ current in cat cerebral vascular smooth muscle.
Collapse
Affiliation(s)
- A Lange
- Cardiovascular Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | | | | | | |
Collapse
|
19
|
A postsynaptic excitatory amino acid transporter with chloride conductance functionally regulated by neuronal activity in cerebellar Purkinje cells. J Neurosci 1997. [PMID: 9278537 DOI: 10.1523/jneurosci.17-18-07017.1997] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Excitatory amino acid (EAA) neurotransmitters induce postsynaptic depolarization by activating receptor-mediated cation conductances, a process known to underlie changes in synaptic efficacy. Using a patch-clamp method, we demonstrate here an EAA-dependent postsynaptic anion conductance mediated by EAA transporters present on cerebellar Purkinje cell bodies and dendrites in culture. This transporter-mediated current was modulated by neuronal activity: it exhibited facilitation for >20 min after transient depolarization accompanied by Ca2+ influx. Evidence is presented suggesting that the transporter facilitation is mediated by arachidonate release after Ca2+-dependent activation of phospholipase A2, which exists in Purkinje cells. This postsynaptic reuptake system may represent a novel modulatory mechanism of synaptic transmission as well as prevent neuronal excitotoxicity.
Collapse
|
20
|
Sellmayer A, Danesch U, Weber PC. Modulation of the expression of early genes by polyunsaturated fatty acids. Prostaglandins Leukot Essent Fatty Acids 1997; 57:353-7. [PMID: 9430378 DOI: 10.1016/s0952-3278(97)90410-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Expression of early genes is a characteristic immediate cellular response to mitogenic or inflammatory stimulation. Various second messenger systems have been found to transduce the signal from the plasma membrane to the nucleus. Recent observations indicate that in addition to well characterized second messenger systems, polyunsaturated fatty acids, especially the n-6 fatty acid arachidonic acid and its endogenously produced metabolites affect the expression of early genes in different cell types. At least in fibroblasts, the stimulatory effect of arachidonic acid can be antagonized by n-3 polyunsaturated fatty acids. Further identification of the mechanisms through which polyunsaturated fatty acids modulate early gene expression and regulate subsequent cellular responses, like cell growth, may help to define novel concepts in the management of cardiovascular diseases.
Collapse
Affiliation(s)
- A Sellmayer
- Institut für Prophylaxe und Epidemiologie der Kreislaufkrankheiten, Universität München, Munich, Germany
| | | | | |
Collapse
|
21
|
Skinner J, Sinclair C, Romeo C, Armstrong D, Charbonneau H, Rossie S. Purification of a fatty acid-stimulated protein-serine/threonine phosphatase from bovine brain and its identification as a homolog of protein phosphatase 5. J Biol Chem 1997; 272:22464-71. [PMID: 9278397 DOI: 10.1074/jbc.272.36.22464] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
An arachidonic acid-stimulated Ser/Thr phosphatase activity was detected in soluble extracts prepared from rat pituitary clonal GH4C1 cells, rat or bovine brain, and bovine heart. The enzyme activity was purified to homogeneity from bovine brain as a monomer with a Mr of 63,000 and a specific activity of 32 nmol of Pi released per min/mg of protein when assayed in the presence of 10 microM phosphocasein in the absence of lipid. Arachidonic acid stimulated activity 4-14-fold, with half-maximal stimulation at 50-100 microM, when assayed in the presence of a variety of phosphosubstrates including casein, reduced carboxamidomethylated and maleylated lysozyme, myelin basic protein, and histone. Oleic acid, linoleic acid, and palmitoleic acid also stimulated activity; however, saturated fatty acids and alcohol or methyl ester derivatives of fatty acids did not significantly affect activity. The lipid-stimulated phosphatase was identified as the bovine equivalent of protein phosphatase 5 or a closely related homolog by sequence analysis of proteolytic fragments generated from the purified enzyme. When recombinant rat protein phosphatase 5 was expressed as a cleavable glutathione S-transferase fusion protein, the affinity-purified thrombin-cleaved enzyme exhibited a specific activity and sensitivity to arachidonic acid similar to those of the purified bovine brain enzyme. These results suggest that protein phosphatase 5 may be regulated in vivo by a lipid second messenger or another endogenous activator.
Collapse
Affiliation(s)
- J Skinner
- Biochemistry Department, Purdue University, West Lafayette, Indiana 47907, USA
| | | | | | | | | | | |
Collapse
|
22
|
Abstract
Essential fatty acid (EFA)-deficient animals develop severe osteoporosis coupled with increased renal and arterial calcification. This picture is similar to that seen in osteoporosis in the elderly, where the loss of bone calcium is associated with ectopic calcification of other tissues, particularly the arteries and the kidneys. Recent mortality studies indicate that the ectopic calcification may be considerably more dangerous than the osteoporosis itself, since the great majority of excess deaths in women with osteoporosis are vascular and unrelated to fractures or other bone abnormalities. EFAs have now been shown to increase calcium absorption from the gut, in part by enhancing the effects of vitamin D, to reduce urinary excretion of calcium, to increase calcium deposition in bone and improve bone strength and to enhance the synthesis of bone collagen. These desirable actions are associated with reduced ectopic calcification. The interaction between EFA and calcium metabolism deserves further investigation since it may offer novel approaches to osteoporosis and also to the ectopic calcification associated with osteoporosis which seems to be responsible for so many deaths.
Collapse
Affiliation(s)
- M C Kruger
- Department of Physiology, University of Pretoria, South Africa
| | | |
Collapse
|
23
|
Abstract
Many neurohormones stimulate phospholipid hydrolysis and elevate diacylglycerol in the mammalian heart, but the physiological consequences of these intracellular events are unclear. Regulation of myocardial contraction by diacylglycerol was investigated in the present study by releasing the diacylglycerol analogue dioctanoylglycerol (diC8) within adult rat ventricular myocytes by using a light-sensitive caged compound. This approach permitted us to avoid exposure of myocytes to extracellular diC8 and yet to control the amount of diC8 released into the cells. Photorelease of diC8 produced a slowly developing (half-time, 1.9 +/- 0.1 minute; n = 26) but robust (406 +/- 42%) enhancement of twitch amplitude in electrically paced myocytes (0.5 Hz, 1 mmol/L Ca2+, Ringer's solution [pH 7.4], 22 degrees C). This positive inotropic effect was dose dependent, stereospecific for the S-enantiomer of diC8, synergistically enhanced by arachidonic acid, and blocked by the protein kinase C inhibitor chelerythrine. The data provide evidence that diacylglycerol can induce a strong positive inotropic effect in mammalian ventricular muscle, possibly by activating protein kinase C. By contrast, perfusion of diC8 extracellularly onto myocytes caused a 42 +/- 2% decline in twitch amplitude, in accordance with previous reports. To account for this dependence on how diC8 is applied, we postulate that diC8 has distinct physiological actions at intracellular and extracellular sites. The peptide neurohormone endothelin-1, which elevates diacylglycerol in cardiac tissues, produced a positive inotropic effect that was similar to the response to photoreleased diC8. The diacylglycerol/protein kinase C pathway has now become a good candidate for mediator of at least a component of the positive inotropy associated with agents that stimulate phospholipid turnover in adult mammalian myocardium.
Collapse
Affiliation(s)
- Y Pi
- Department of Physiology, University of Wisconsin, Madison 53706, USA
| | | | | | | |
Collapse
|
24
|
Goodfriend TL, Egan BM. Nonesterified fatty acids in the pathogenesis of hypertension: theory and evidence. Prostaglandins Leukot Essent Fatty Acids 1997; 57:57-63. [PMID: 9250609 DOI: 10.1016/s0952-3278(97)90493-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This paper approaches the hypothesis that fatty acids contribute to hypertension by examining possible interactions of nonesterified fatty acids with renal pressure-natriuresis, peripheral vascular resistance, and the central nervous barostat, three loci where long-term regulation of blood pressure is probably controlled. By inhibiting aldosterone secretion, nonesterified fatty acids may lower blood pressure by facilitating pressure-natriuresis. Oxygenated metabolites of fatty acids appear to stimulate aldosterone secretion. In different experimental situations, fatty acids either constrict or dilate arteries. There is no evidence of an effect of fatty acids on the central nervous barostat, but they do sensitize peripheral vessels to alpha-adrenergic stimuli. Obesity and diabetes are marked by increased incidence of hypertension, and elevated levels of fatty acids or their P450 oxygenated metabolites may contribute to this association. Drugs that influence plasma fatty acids, like heparin, do not have reproducible effects on blood pressure. Experimental evidence suggests but does not prove that nonesterified fatty acids can affect the long-term set-point of blood pressure.
Collapse
Affiliation(s)
- T L Goodfriend
- William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA
| | | |
Collapse
|
25
|
Stuhlmeier KM, Tarn C, Bach FH. The effect of 5,8,11,14-eicosatetraynoic acid on endothelial cell gene expression. Eur J Pharmacol 1997; 325:209-19. [PMID: 9163568 DOI: 10.1016/s0014-2999(97)00117-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The endothelium plays a key role in inflammation, hemostasis and organ rejection. We report here that a synthetic polyunsaturated fatty acid, 5,8,11,14-eicosatetraynoic acid (ETYA), selectively inhibits the up-regulation of several genes on endothelial cells. ETYA suppresses endothelial cell activation by inhibiting the up-regulation of adhesion molecules like E-selectin. A runoff assay for E-selectin demonstrated that the suppression is at the level of transcription. The fact that ETYA inhibits E-selectin upon stimulation with a diverse group of stimuli like lipopolysaccharide, tumor necrosis factor-alpha or phorbol 12-myristate 13-acetate, suggests that ETYA does not exert its effect by modifying membrane-bound receptors. The messenger RNA for interleukin-8 and glyceraldehyde phosphate dehydrogenase are not affected. Pre-treatment of endothelial cells with ETYA also prevents the adherence of monocytes to tumor necrosis factor-alpha-stimulated cells.
Collapse
Affiliation(s)
- K M Stuhlmeier
- Sandoz Center for Immunobiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA.
| | | | | |
Collapse
|
26
|
Nowicki S, Chen SL, Aizman O, Cheng XJ, Li D, Nowicki C, Nairn A, Greengard P, Aperia A. 20-Hydroxyeicosa-tetraenoic acid (20 HETE) activates protein kinase C. Role in regulation of rat renal Na+,K+-ATPase. J Clin Invest 1997; 99:1224-30. [PMID: 9077530 PMCID: PMC507936 DOI: 10.1172/jci119279] [Citation(s) in RCA: 130] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
It is well documented that the activity of Na+,K+-ATPase can be inhibited by the arachidonic acid metabolite, 20-hydroxyeicosa-tetraenoic acid (20 HETE). Evidence is presented here that this effect is mediated by protein kinase C (PKC). PKC inhibitors abolished 20 HETE inhibition of rat Na+,K+-ATPase in renal tubular cells. 20 HETE caused translocation of PKC alpha from cytoplasm to membrane in COS cells. It also inhibited Na+,K+-ATPase activity in COS cells transfected with rat wild-type renal Na+,K+-ATPase alpha1 subunit, but not in cells transfected with Na+,K+-ATPase alpha1, where the PKC phosphorylation site, serine 23, had been mutated to alanine. PKC-induced phosphorylation of rat renal Na+,K+-ATPase, as well as of histone was strongly enhanced by 20 HETE at the physiologic calcium concentration of 1.3 microM, but not at the calcium concentration of 200 microM. The results indicate that phospholipase A2-arachidonic acid-20 HETE pathway can exert important biological effects via activation of PKC and that this effect may occur in the absence of a rise in intracellular calcium.
Collapse
Affiliation(s)
- S Nowicki
- Department of Women and Child Health, Karolinska Institute, Stockholm, Sweden
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Park KW, Dai HB, Lowenstein E, Sellke FW. Protein kinase C-induced contraction is inhibited by halothane but enhanced by isoflurane in rat coronary arteries. Anesth Analg 1996; 83:286-90. [PMID: 8694307 DOI: 10.1097/00000539-199608000-00015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Protein kinase C (PKC), important in signal transduction, may help generate and maintain vascular smooth muscle tone. We sought to examine the effect of the volatile anesthetics isoflurane and halothane on PKC agonist-induced vasoconstriction and PKC inhibitor-induced vasorelaxation. Subepicardial resistance arteries were dissected from rat hearts. Changes in vessel diameters were monitored in response to the membrane-bound PKC agonist 12-deoxyphorbol-13-isobutyric-20-acetate (PBE) 10(-8)-10(-7) M or the cytosolic PKC agonist oleic acid 10(-7)-10(-5.5) M either in the presence of isoflurane 1.15%, isoflurane 2.3%, halothane 0.77%, halothane 1.54%, or no volatile anesthetics (control). In addition, after preconstriction with the thromboxane analog U46619 1 microM, relaxation responses to the PKC inhibitor staurosporine 10(-8)-10(-7) M were examined in the presence or absence of the anesthetics as above. PBE-induced constriction was attenuated by either concentration of halothane (P < 0.05) but was unaltered by isoflurane (P > 0.5). Oleic acid-induced constriction was abolished by halothane (P < 0.001) but enhanced by isoflurane (P < 0.01). Staurosporine-induced relaxation of U46619-preconstricted vessels was attenuated by isoflurane (P < 0.05) but unaltered by halothane (P > 0.3). We conclude that isoflurane may enhance cytosolic PKC-mediated vasoconstriction, whereas halothane may attenuate both cytosolic and membrane-bound PKC-mediated vasoconstriction.
Collapse
Affiliation(s)
- K W Park
- Department of Anesthesia, Beth Israel Hospital, Harvard Medical School, Boston, Massachusetts 02215, USA
| | | | | | | |
Collapse
|
28
|
Park KW, Dai HB, Lowenstein E, Sellke FW. Protein Kinase C-Induced Contraction Is Inhibited by Halothane but Enhanced by Isoflurane in Rat Coronary Arteries. Anesth Analg 1996. [DOI: 10.1213/00000539-199608000-00015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|