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  • 1
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    Online Resource
    Caspase-mediated degradation of human 5-lipoxygenase in B lymphocytic cells
    Proceedings of the National Academy of Sciences ; 2005
    In:  Proceedings of the National Academy of Sciences Vol. 102, No. 37 ( 2005-09-13), p. 13164-13169
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 102, No. 37 ( 2005-09-13), p. 13164-13169
    Abstract: 5-Lipoxygenase (5-LO) is a tightly regulated enzyme in the synthesis of bioactive lipids from arachidonic acid. Here, we demonstrate that 5-LO is regulated by caspases, which are signaling molecules that control critical biological processes by means of specific limited proteolysis. Cell splitting of the Epstein–Barr virus-transformed B lymphocytic cell line BL41-E95-A caused a pronounced, but transient, reduction of functional 5-LO protein, ac-companied by the appearance of a 62-kDa 5-LO cleavage product. In parallel, splitting of BL41-E95-A cells induced activation of caspase-6 (casp-6) and casp-8. Caspase activation and 5-LO degradation were blocked by the protein-synthesis inhibitor cycloheximide, and cell-permeable peptide inhibitors of casp-6 and casp-8 prevented 5-LO cleavage. Activation of casp-6 and casp-8 was connected to subsequent enhancement of cell proliferation, whereas selective caspase inhibition blocked cell growth. Last, isolated human 5-LO was cleaved by recombinant casp-6 in vitro to a 58-kDa fragment. Based on site-directed mutagenesis studies, 5-LO is cleaved by casp-6 after Asp-170, which in a homology-based 3D model of 5-LO is located on the enzyme periphery. We suggest that splitting of BL41-E95-A cells induces de novo synthesis of a protein involved in the activation of casp-6, which cleaves 5-LO.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0505991102
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2005
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  • 2
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    Online Resource
    Coactosin-like protein supports 5-lipoxygenase enzyme activity and up-regulates leukotriene A 4 production
    Proceedings of the National Academy of Sciences ; 2006
    In:  Proceedings of the National Academy of Sciences Vol. 103, No. 35 ( 2006-08-29), p. 13150-13155
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 103, No. 35 ( 2006-08-29), p. 13150-13155
    Abstract: Regulation of 5-lipoxygenase (5LO) activity is a key determinant for the biosynthesis of proinflammatory leukotrienes. Coactosin-like protein (CLP) is an F-actin-binding protein that can also bind 5LO. Here, we report that CLP can up-regulate and modulate 5LO activity [formation of 5( S )-hydroperoxy-6- trans -8,11,14- cis -eicosatetraenoic acid (5-HPETE)], 5( S )-hydroxy-6- trans -8,11,14- cis -eicosatetraenoic acid (5-HETE), and 5( S )- trans -5,6-oxido-7,9- trans -11,14- cis -eicosatetraenoic acid (LTA 4 ) in vitro . Three findings are presented. First, CLP up-regulates Ca 2+ -induced 5LO activity, in the absence of phosphatidylcholine (membrane). Apparently, CLP can function as a scaffold for 5LO, similar to membranes. Second, CLP gives a considerable (3-fold) increase in the amount of LTA 4 formed by 5LO, when present together with phosphatidylcholine. Third, CLP increases the ratio of 5-HETE/5-HPETE. These effects require protein interaction by Trp residues in ligand-binding loops of the 5LO β-sandwich; both binding and stimulatory effects of CLP were abolished for the mutant 5LO-W13/75/102A. In polymorphonuclear leukocytes stimulated with Ca 2+ ionophore, both CLP and 5LO associated with the nucleus, whereas in resting cells, CLP and 5LO were cytosolic. These findings establish CLP as a factor relevant for 5LO product formation. Functioning as a 5LO scaffold, CLP may provide a basis for the formation of 5-HETE in the cytosol of different cell types. Furthermore, in stimulated cells, CLP appears to function in a complex together with 5LO and membranes, increasing the capacity of 5LO for leukotriene biosynthesis.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0605150103
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2006
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 3
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    Online Resource
    Glucocorticoids regulate lipid mediator networks by reciprocal modulation of 15-lipoxygenase isoforms affecting inflammation resolution
    Proceedings of the National Academy of Sciences ; 2023
    In:  Proceedings of the National Academy of Sciences Vol. 120, No. 35 ( 2023-08-29)
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 120, No. 35 ( 2023-08-29)
    Abstract: Glucocorticoids (GC) are potent anti-inflammatory agents, broadly used to treat acute and chronic inflammatory diseases, e.g., critically ill COVID-19 patients or patients with chronic inflammatory bowel diseases. GC not only limit inflammation but also promote its resolution although the underlying mechanisms are obscure. Here, we reveal reciprocal regulation of 15-lipoxygenase (LOX) isoform expression in human monocyte/macrophage lineages by GC with respective consequences for the biosynthesis of specialized proresolving mediators (SPM) and their 15-LOX-derived monohydroxylated precursors (mono-15-OH). Dexamethasone robustly up-regulated pre-mRNA, mRNA, and protein levels of ALOX15B/15-LOX-2 in blood monocyte–derived macrophage (MDM) phenotypes, causing elevated SPM and mono-15-OH production in inflammatory cell types. In sharp contrast, dexamethasone blocked ALOX15/15-LOX-1 expression and impaired SPM formation in proresolving M2-MDM. These dexamethasone actions were mimicked by prednisolone and hydrocortisone but not by progesterone, and they were counteracted by the GC receptor (GR) antagonist RU486. Chromatin immunoprecipitation (ChIP) assays revealed robust GR recruitment to a putative enhancer region within intron 3 of the ALOX15B gene but not to the transcription start site. Knockdown of 15-LOX-2 in M1-MDM abolished GC-induced SPM formation and mono-15-OH production. Finally, ALOX15B/15-LOX-2 upregulation was evident in human monocytes from patients with GC-treated COVID-19 or patients with IBD. Our findings may explain the proresolving GC actions and offer opportunities for optimizing GC pharmacotherapy and proresolving mediator production.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.2302070120
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2023
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 4
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    Online Resource
    ERK-mediated regulation of leukotriene biosynthesis by androgens: A molecular basis for gender differences in inflammation and asthma
    Proceedings of the National Academy of Sciences ; 2008
    In:  Proceedings of the National Academy of Sciences Vol. 105, No. 50 ( 2008-12-16), p. 19881-19886
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 105, No. 50 ( 2008-12-16), p. 19881-19886
    Abstract: 5-Lipoxygenase initiates the biosynthesis of leukotrienes, lipid mediators involved in normal host defense and in inflammatory and allergic disorders. Despite an obvious gender bias in leukotriene-related diseases (e.g., asthma), gender aspects have been neglected in studies on leukotrienes and 5-lipoxygenase. Here, we show that leukotriene formation in stimulated whole blood or neutrophils from males is substantially lower compared with females, accompanied by changed 5-lipoxygenase trafficking. This is due to gender-specific differential activation of extracellular signal-regulated kinases (ERKs). The differences are directly related to variant male/female testosterone plus 5α-dihydrotestosterone levels, and addition of 5α-dihydrotestosterone to female blood or neutrophils reduced the high (female) LT biosynthesis capacity to low (male) levels. In conclusion, regulation of ERKs and leukotriene formation by androgens constitutes a molecular basis for gender differences in the inflammatory response, and in inflammatory diseases such as asthma.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0809120105
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2008
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    5-Lipoxygenase is phosphorylated by p38 kinase-dependent MAPKAP kinases
    Proceedings of the National Academy of Sciences ; 2000
    In:  Proceedings of the National Academy of Sciences Vol. 97, No. 10 ( 2000-05-09), p. 5261-5266
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 97, No. 10 ( 2000-05-09), p. 5261-5266
    Abstract: 5-lipoxygenase (5-LO) catalyzes the initial steps in the formation of leukotrienes, a group of inflammatory mediators derived from arachidonic acid (AA). Here we describe that activation of p38 mitogen-activated protein kinase in human polymorphonuclear leukocytes and in Mono Mac 6 cells leads to activation of downstream kinases, which can subsequently phosphorylate 5-LO in vitro . Different agents activated the 5-LO kinase activities, including stimuli for cellular leukotriene biosynthesis (A23187, thapsigargin, N -formyl-leucyl-phenylalanine), compounds that up-regulate the capacity for leukotriene biosynthesis (phorbol 12-myristate 13-acetate, tumor necrosis factor α, granulocyte/macrophage colony-stimulating factor), and well known p38 stimuli as sodium arsenite and sorbitol. For all stimuli, 5-LO kinase activation was counteracted by SB203580 (3 μM or less), an inhibitor of p38 kinase. At least two p38-dependent 5-LO kinase activities were found. Based on migration properties in in-gel kinase assays and immunoreactivity, one of these was identified as mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP kinase 2). The other appeared to be MAPKAP kinase 3; however, it could not be excluded that also other p38-dependent kinases contributed. When polymorphonuclear leukocytes were incubated with sodium arsenite (strong activator of 5-LO kinases), platelet-activating factor and exogenous AA, there was a 4-fold increase in 5-LO activity as compared with incubations with only platelet-activating factor and AA. This indicates that 5-LO phosphorylation can be one factor determining cellular 5-LO activity.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.050588997
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2000
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 6
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    Online Resource
    Arachidonoyl-phosphatidylcholine oscillates during the cell cycle and counteracts proliferation by suppressing Akt membrane binding
    Proceedings of the National Academy of Sciences ; 2013
    In:  Proceedings of the National Academy of Sciences Vol. 110, No. 7 ( 2013-02-12), p. 2546-2551
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 110, No. 7 ( 2013-02-12), p. 2546-2551
    Abstract: The activity of protein kinase B (Akt)—a major kinase promoting cell proliferation and survival—oscillates during the cell cycle. To investigate whether membrane phospholipids may regulate Akt phosphorylation and thus activity, we monitored the lipid profile of nocodazole-synchronized mouse NIH 3T3 fibroblasts during the cell cycle by liquid chromatography electrospray ionization tandem mass spectrometry (LC-MS/MS). The proportion of sn -2-arachidonoyl-phosphatidylcholine (20:4-PC) inversely correlated with Akt activity. Increasing the cellular ratio of 20:4-PC by supplementation of 20:4-PC to the cell culture medium diminished Akt [serine (Ser)473] phosphorylation. Saturated and monounsaturated phosphatidylcholines, used as control had no effect; 20:4-PC reduced cell proliferation relative to controls, interfered with S-phase transition, and suppressed Akt downstream signaling and cyclin expression like LY294002, which is a specific inhibitor of the phosphatidylinositol-3-kinase/Akt pathway. Additive effects of 20:4-PC and LY294002 were not observed, underlining the critical role of Akt for 20:4-PC signaling; 20:4-PC suppressed Akt membrane translocation as shown by immunofluorescence microscopy but left the concentration of the anchor lipid phosphatidylinositol-3,4,5-trisphosphate unchanged. An in vitro binding assay suggests that 20:4-PC attenuates the interaction of Akt with its membrane binding site. We conclude that 20:4-PC oscillates during the cell cycle and delays cell cycle progression by inhibiting Akt membrane binding.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1216182110
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2013
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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