| 1. |
- Berg, Cecilia, 1976-, et al.
(author)
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Platelet-induced growth of human fibroblasts is associated with an increased expression of 5-lipoxygenase
- 2006
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In: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 96:5, s. 652-659
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Journal article (peer-reviewed)abstract
- Proliferation of fibroblasts is vital for adequate wound healing but is probably also involved in different hyperproliferative disorders such as atherosclerosis and cancer. The regeneration of tissue usually starts with coagulation, involving release of mitogenic and inflammatory factors from activated platelets. This study focuses on the role of eicosanoids in the proliferative effects of platelets on human fibroblasts. We show that the phospholipase A2 inhibitor 7,7-dimethyl-5,8-eicosadienoic acid (DMDA), the combined cyclooxygenase (COX) and lipoxygenase (LOX) inhibitor 5,8,11,14-eicosatetraynoic acid (ETYA) and the LOX inhibitor 5,8,11-eicosatriynoic acid (ETI) block the platelet-induced proliferation of serum starved subconfluent human fibroblasts. Anti-proliferative effects were also obtained by specific inhibition of 5-LOX with 5,6-dehydro arachidonic acid (5,6-dAA), whereas the 12-LOX inhibitor cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC) did not affect the platelet-stimulated growth of fibroblasts. The expression of 5-LOX was analyzed by reverse-transcriptase-mediated PCR (RT-PCR), Western blotting and HPLC. 5-LOX message and protein was detected in fibroblasts but not in platelets. Incubation with platelets markedly increased, already after one hour, the expression of 5-LOX in the fibroblast culture. The increased 5-LOX activity was associated with an elevated level of the 5-LOX metabolite 5-hydroxyeicosatetraenoic acid (5-HETE) reaching its maximum after 1-2 hours of co-incubation of fibroblasts and platelets. The 5-HETE production was reduced by the inhibitors DMDA, ETYA and ETI. In conclusion, this study suggests that platelet-stimulated proliferation of fibroblasts is mediated by an increased 5-LOX activity, which supports recent findings indicating a crucial role for this enzyme in proliferative disorders such as atherosclerosis. © 2006 Schattauer GmbH, Stuttgart.
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| 2. |
- Börjesson, Sara, 1982-, et al.
(author)
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Lipoelectric modification of ion channel voltage gating by polyunsaturated fatty acids
- 2008
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In: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 95:5, s. 2242-2253
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Journal article (peer-reviewed)abstract
- Polyunsaturated fatty acids (PUFAs) have beneficial effects on epileptic seizures and cardiac arrhythmia. We report that ω-3 and ω-6 all-cis-PUFAs affected the voltage dependence of the Shaker K channel by shifting the conductance versus voltage and the gating charge versus voltage curves in negative direction along the voltage axis. Uncharged methyl esters of the PUFAs did not affect the voltage dependence, whereas changes of pH and charge mutations on the channel surface affected the size of the shifts. This suggests an electrostatic effect on the channel's voltage sensors. Monounsaturated and saturated fatty acids, as well as trans-PUFAs did not affect the voltage dependence. This suggests that fatty acid tails with two or more cis double bonds are required to place the negative carboxylate charge of the PUFA in a position to affect the channel's voltage dependence. We propose that charged lipophilic compounds could play a role in regulating neuronal excitability by electrostatically affecting the channel's voltage sensor. We believe this provides a new approach for pharmacological treatment that is voltage sensor pharmacology. © 2008 by the Biophysical Society.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Kurahashi, Yuko, et al.
(author)
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A 12(S)-hydroxyeicosatetraenoic acid receptor interacts with steroid receptor coactivator-1
- 2000
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In: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 97:11, s. 5779-5783
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Journal article (peer-reviewed)abstract
- Lewis lung carcinoma cells contain specific high-affinity binding sites for the eicosanoid 12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid [12(S)-HETE]. These binding sites have a cytosolic/nuclear localization and contain the heat shock proteins hsp70 and hsp90 as components of a high molecular weight cytosolic binding complex. The ligand binding subunit of this complex is a protein with an apparent molecular mass of ÿ50 kDa as judged by gel permeation chromatography. In this report, we present data showing that the 50-kDa 12(S)-HETE binding protein interacts as a homodimer with steroid receptor coactivator-1 (SRC-1) in the presence of 12(S)-HETE. Two putative interaction domains were mapped. One of these (amino acids 701-781) was within the nuclear receptor interaction domain in SRC-1 required for binding of various steroid and thyroid hormone receptors. It contains the most C-terminal of the three copies of LXXLL motif present in the nuclear receptor interaction domain. The second interaction domain was present in the N-terminal part of SRC-1 (amino acids 1-221). This region has two LXXLL motifs, one does not bind and the other binds only weakly to steroid and thyroid hormone receptors. Glutathione S-transferase (GST) pulldown experiments and far Western analyses demonstrated that the N-terminal region of SRC-1 (amino acids 1-212) alone does not bind the 50-kDa 12(S)-HETE binding protein, whereas GST/?SRC-11-1138 ligand-dependently pulled down a protein of ÿ50 kDa in size. Our results suggest that the 50-kDa 12(S)-HETE binding protein is a receptor that may signal through interaction with a nuclear receptor coactivator protein.
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| 8. |
- Maccari, Maria Elena, et al.
(author)
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Activated phosphoinositide 3-kinase δ syndrome: Update from the ESID Registry and comparison with other autoimmune-lymphoproliferative inborn errors of immunity.
- 2023
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In: The Journal of allergy and clinical immunology. - 1097-6825. ; 152:4
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Journal article (peer-reviewed)abstract
- Activated phosphoinositide-3-kinase δ syndrome (APDS) is an inborn error of immunity (IEI) with infection susceptibility and immune dysregulation, clinically overlapping with other conditions. Management depends on disease evolution, but predictors of severe disease are lacking.This study sought to report the extended spectrum of disease manifestations in APDS1 versus APDS2; compare these to CTLA4 deficiency, NFKB1 deficiency, and STAT3 gain-of-function (GOF) disease; and identify predictors of severity in APDS.Data was collected from the ESID (European Society for Immunodeficiencies)-APDS registry and was compared with published cohorts of the other IEIs.The analysis of 170 patients with APDS outlines high penetrance and early onset of APDS compared to the other IEIs. The large clinical heterogeneity even in individuals with the same PIK3CD variant E1021K illustrates how poorly the genotype predicts the disease phenotype and course. The high clinical overlap between APDS and the other investigated IEIs suggests relevant pathophysiological convergence of the affected pathways. Preferentially affected organ systems indicate specific pathophysiology: bronchiectasis is typical of APDS1; interstitial lung disease and enteropathy are more common in STAT3 GOF and CTLA4 deficiency. Endocrinopathies are most frequent in STAT3 GOF, but growth impairment is also common, particularly in APDS2. Early clinical presentation is a risk factor for severe disease in APDS.APDS illustrates how a single genetic variant can result in a diverse autoimmune-lymphoproliferative phenotype. Overlap with other IEIs is substantial. Some specific features distinguish APDS1 from APDS2. Early onset is a risk factor for severe disease course calling for specific treatment studies in younger patients.
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| 9. |
- Meruvu, Sunitha, et al.
(author)
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Sequence determinants for the reaction specificity of murine (12R)-lipoxygenase : Targeted substrate modification and site-directed mutagenesis
- 2005
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In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 280:44, s. 36633-36641
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Journal article (peer-reviewed)abstract
- Mammalian lipoxygenases (LOXs) are categorized with respect to their positional specificity of arachidonic acid oxygenation. Site-directed mutagenesis identified sequence determinants for the positional specificity of these enzymes, and a critical amino acid for the stereoselectivity was recently discovered. To search for sequence determinants of murine (12R)-LOX, we carried out multiple amino acid sequence alignments and found that Phe390, Gly441, Ala455, and Val631 align with previously identified positional determinants of S-LOX isoforms. Multiple site-directed mutagenesis studies on Phe390 and Ala455 did not induce specific alterations in the reaction specificity, but yielded enzyme species with reduced specific activities and stereo random product patterns. Mutation of Gly441 to Ala, which caused drastic alterations in the reaction specificity of other LOX isoforms, failed to induce major alterations in the positional specificity of mouse (12R)-LOX, but markedly modified the enantioselectivity of the enzyme. When Val631, which aligns with the positional determinant He593 of rabbit 15-LOX, was mutated to a less space-filling residue (Ala or Gly), we obtained an enzyme species with augmented catalytic activity and specifically altered reaction characteristics (major formation of chiral (11R)-hydroxyeicosatetraenoic acid methyl ester). The importance of Val631 for the stereo control of murine (12R)-LOX was confirmed with other substrates such as methyl linoleate and 20-hydroxyeicosatetraenoic acid methyl ester. These data identify Val 631 as the major sequence determinant for the specificity of murine (12R)-LOX. Furthermore, we conclude that substrate fatty acids may adopt different catalytically productive arrangements at the active site of murine (12R)-LOX and that each of these arrangements may lead to the formation of chiral oxygenation products. © 2005 by The American Society for Biochemistry and Molecular Biology, Inc.
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| 10. |
- Strid, Tobias, et al.
(author)
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Leukotriene C4 synthase promoter driven expression of GFP reveals cell specificity
- 2008
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In: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 366:1, s. 80-85
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Journal article (peer-reviewed)abstract
- Leukotriene C4 synthase is a key enzyme in leukotriene biosynthesis. Its gene has been cloned and mapped to mouse chromosome 11. Expression occurs in cells of myeloid origin and also in the choroid plexus, the hypothalamus and the medial eminence of mouse brain. In this study a vector that expresses enhanced green fluorescent protein (eGFP) under the control of the mouse leukotriene C4 synthase promoter was constructed and used to study promoter activity in different cell lines. Specific eGFP expression was observed in human monocytic leukemia (THP-1) and rat basophilic leukemia (RBL-1) myeloid cells which both express leukotriene C4 synthase, but not in human embryonic kidney (HEK293/T) epithelial cells which do not express this enzyme. In the myeloid cells, but not in the epithelial cells, we observed that the leukotriene C4 synthase promoter activity was stimulated by 12-O-tetradecanoylphorbol-13-acetate and all-trans-retinoic acid. In contrast dimethyl sulfoxide did not affect promoter activity. © 2007 Elsevier Inc. All rights reserved.
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| 11. |
- Svartz, Jesper, 1972-, et al.
(author)
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Identification of regions of leukotriene C4 synthase which direct the enzyme to its nuclear envelope localization
- 2006
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In: Journal of Cellular Biochemistry. - : Wiley. - 0730-2312 .- 1097-4644. ; 98:6, s. 1517-1527
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Journal article (peer-reviewed)abstract
- Leukotrienes (LTs) are fatty acid derivatives formed by oxygenation of arachidonic acid via the 5-lipoxygenase (5-LO) pathway. Upon activation of inflammatory cells 5-LO is translocated to the nuclear envelope (NE) where it converts arachidonic acid to the unstable epoxide LTA4. LTA4 is further converted to LTC4 by conjugation with glutathione, a reaction catalyzed by the integral membrane protein LTC4 synthase (LTC4S), which is localized on the NE and endoplasmic reticulum (ER). We now report the mapping of regions of LTC4S that are important for its subcellular localization. Multiple constructs encoding fusion proteins of green fluorescent protein (GFP) as the N-terminal part and various truncated variants of human LTC4S as C-terminal part were prepared and transfected into HEK 293/T or COS-7 cells. Constructs encoding hydrophobic region 1 of LTC4S (amino acids 6–27) did not give distinct membrane localized fluorescence. In contrast hydrophobic region 2 (amino acids 60–89) gave a localization pattern similar to that of full length LTC4S. Hydrophobic region 3 (amino acids 114–135) directed GFP to a localization indistinguishable from that of full length LTC4S. A minimal directing sequence, amino acids 117–132, was identified by further truncation. The involvement of the hydrophobic regions in the homo-oligomerization of LTC4S was investigated using bioluminescence resonance energy transfer (BRET) analysis in living cells. BRET data showed that hydrophobic regions 1 and 3 each allowed oligomerization to occur. These regions most likely form transmembrane helices, suggesting that homo-oligomerization of LTC4S is due to helix–helix interactions in the membrane.
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| 12. |
- Svartz, Jesper, 1972-, et al.
(author)
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Leukotriene C4 synthase homo-oligomers detected in living cells by bioluminescence resonance energy transfer
- 2003
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In: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. - : Elsevier. - 1388-1981 .- 1879-2618. ; 1633:2, s. 90-95
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Journal article (peer-reviewed)abstract
- Leukotrienes (LTs) are biologically active compounds derived from arachidonic acid which have important pathophysiological roles in asthma and inflammation. The cysteinyl leukotriene LTC4 and its metabolites LTD4 and LTE4 stimulate bronchoconstriction, airway mucous formation and generalized edema formation. LTC4 is formed by addition of glutathione to LTA4, catalyzed by the integral membrane protein, LTC4 synthase (LTCS). We now report the use of bioluminescence resonance energy transfer (BRET) to demonstrate that LTCS forms homo-oligomers in living cells. Fusion proteins of LTCS and Renilla luciferase (Rluc) and a variant of green fluorescent protein (GFP), respectively, were prepared. High BRET signals were recorded in transiently transfected human embryonic kidney (HEK 293) cells co-expressing Rluc/LTCS and GFP/LTCS. Homo-oligomer formation in living cells was verified by co-transfection of a plasmid expressing non-chimeric LTCS. This resulted in dose-dependent attenuation of the BRET signal. Additional evidence for oligomer formation was obtained in cell-free assays using glutathione S-transferase (GST) pull-down assay. To map interaction domains for oligomerization, GFP/LTCS fusion proteins were prepared with truncated variants of LTCS. The results obtained identified a C-terminal domain (amino acids 114–150) sufficient for oligomerization of LTCS. Another, centrally located, interaction domain appeared to exist between amino acids 57–88. The functional significance of LTCS homo-oligomer formation is currently being investigated.
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| 13. |
- Söderström, Mats, 1958-, et al.
(author)
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Expression of leukotriene C4 synthase mRNA by the choroid plexus in mouse brain suggests novel neurohormone functions of cysteinyl leukotrienes
- 2003
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In: Biochemical and Biophysical Research Communications - BBRC. - 0006-291X .- 1090-2104. ; 307:4, s. 987-990
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Journal article (peer-reviewed)abstract
- Leukotriene C4 is a potent mediator of allergic and inflammatory reactions, and is formed from arachidonic acid and glutathione through the sequential action of 5-lipoxygenase and leukotriene C4 synthase (LTCS). These enzymes are predominantly expressed in cells of myeloid lineage. In this report, we have investigated LTCS mRNA expression in mouse brain. Expression was demonstrated using RT-PCR and RNase protection assays. In situ hybridization experiments showed exclusive staining of the choroid plexus of all brain ventricles. This expression pattern may provide a mechanism for the generation of LTC4 on the cerebral side of the blood-brain barrier and suggests a possible novel regulator function of LTC4 in the formation of cerebrospinal fluid.
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| 14. |
- Wigren, Jane, 1967-, et al.
(author)
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Differential recruitment of the coactivator proteins CREB-binding protein and steroid receptor coactivator-1 to peroxisome proliferator-activated receptor gamma/9-cis-retinoic acid receptor heterodimers by ligands present in oxidized low-density lipoprotein
- 2003
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In: Journal of Endocrinology. - : Bioscientifica. - 0022-0795 .- 1479-6805. ; 177:2, s. 207-214
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Journal article (peer-reviewed)abstract
- Peroxisome proliferator-activated receptor gamma (PPAR?) colocalizes with oxidized low-density lipoprotein (LDL) in foam cells in atherosclerotic lesions. We have explored a potential role of oxidized fatty acids in LDL as PPAR? activators. LDL from patients suffering from intermittent claudication due to atherosclerosis was analyzed using HPLC and gas chromatography/mass spectrophotometry and found to contain 9-hydroxy-and 13-hydroxyoctadecadienoic acid (9- and 13-HODE), as well as 5-hydroxy-, 12-hydroxy- and 15-hydroxyeicosatetraenoic acid (5-, 12- and 15-HETE respectively). PPAR? was potently activated by 13(S)-HODE and 15(S)-HETE, as judged by transient transfection assays in macrophages or CV-1 cells. 5(S)- and 12(S)-HETE as well as 15-deoxy-?12,14 -prostaglandin J2 also activated PPAR? but were less potent. Interestingly, the effect of the lipoxygenase products 13(S -HODE and 15(S)-HETE as well as of the drug rosiglitazone were preferentially enhanced by the coactivator CREB-binding protein, whereas the effect of the cyclooxygenase product 15-deoxy-?12,14-prostaglandin J2 was preferentially enhanced by steroid receptor coactivator-1. We interpret these results, which may have relevance to the pathogenesis of atherosclerosis, to indicate that the lipoxygenase products on the one hand and the cyclooxygenase product on the other exert specific effects on the transcription of target genes through differential coactivator recruitment by PPAR?/9-cis retinoic acid receptor heterodimer complexes.
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