![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-3-Methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione) Potently Inhibits Human 5-Lipoxygenase in Vivo and in Vitro
Institute of Pharmaceutical Chemistry, University of Frankfurt, Frankfurt, Germany
Abstract
U-73122 (1-[6-[[17-
-3-methoxyestra-1,3,5(10)-trien-17-yl]amino] hexyl]-1H-pyrrole-2,5-dione) is a widely used antagonist of phosphoinositide-specific phospholipase C (PLC) and is frequently used to define a role of PLC in receptor-mediated elevation of intracellular calcium concentration ([Ca2+]i). In human polymorphonuclear leukocytes (PMNLs), U-73122 inhibited increases in [Ca2+]i induced by G protein-coupled receptor (GPCR) agonists (N-formyl-methionyl-leucyl-phenylalanine or platelet-activating factor; IC50 of 
2 to 4 µM), but it failed to suppress responses induced by ionomycin or thapsigargin. 5-Lipoxygenase (5-LO) is a Ca2+-regulated enzyme that can be activated in leukocytes by stimuli that elevate [Ca2+]i. Attempts to investigate the involvement of PLC in cellular 5-LO activation revealed that U-73122 suppresses 5-LO product synthesis regardless of the stimulus and independently of Ca2+. Thus, U-73122 blocked 5-LO product synthesis induced by cell stress, involving 5-LO phosphorylation pathways in the absence of Ca2+ with an IC50 of 2 µM. Direct inhibition of 5-LO by U-73122 was evident in PMNL homogenates (IC50 of 2.4 µM), and isolated human recombinant 5-LO enzyme was potently inhibited by U-73122 (IC50 of 30 nM). Thiols (glutathione) strongly blunted the effect of U-73122 on isolated 5-LO. On the other hand, depletion of cellular thiols by N-ethylmaleimide strongly increased the efficacy of U-73122 to inhibit 5-LO in intact cells or corresponding homogenates, suggesting that U-73122 may interfere with sulfhydryl groups on 5-LO. Since 5-LO products induce increases in [Ca2+]i via GPCRs, caution should be used when interpreting data where U-73122 is used as tool to determine a direct role of PLC in receptor-mediated Ca2+ mobilization.
Address correspondence to: Dr. Oliver Werz, Institute of Pharmaceutical Chemistry, University of Frankfurt, Marie-Curie Strasse 9, D-60439 Frankfurt, Germany. E-mail: o.werz{at}pharmchem.uni-frankfurt.de
This article has been cited by other articles:
|
|
 |
|
  E. A. Woodcock, P. M. Kistler, and Y. Ju Phosphoinositide signalling and cardiac arrhythmias Cardiovasc Res, November 11, 2008; (2008) cvn283v2. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K.-i. Otsuguro, J. Tang, Y. Tang, R. Xiao, M. Freichel, V. Tsvilovskyy, S. Ito, V. Flockerzi, M. X. Zhu, and A. V. Zholos Isoform-specific Inhibition of TRPC4 Channel by Phosphatidylinositol 4,5-Bisphosphate J. Biol. Chem., April 11, 2008; 283(15): 10026 - 10036. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Albert, C. Pergola, A. Koeberle, G. Dodt, D. Steinhilber, and O. Werz The role of diacylglyceride generation by phospholipase D and phosphatidic acid phosphatase in the activation of 5-lipoxygenase in polymorphonuclear leukocytes J. Leukoc. Biol., April 1, 2008; 83(4): 1019 - 1027. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. E. Wilsher, W. J. Court, R. Ruddle, Y. M. Newbatt, W. Aherne, P. W. Sheldrake, N. P. Jones, M. Katan, S. A. Eccles, and F. I. Raynaud The Phosphoinositide-Specific Phospholipase C Inhibitor U73122 (1-(6-((17{beta}-3-Methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione) Spontaneously Forms Conjugates with Common Components of Cell Culture Medium Drug Metab. Dispos., July 1, 2007; 35(7): 1017 - 1022. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Helling, A. Possart, S. Cottier, U. Klahre, and B. Kost Pollen Tube Tip Growth Depends on Plasma Membrane Polarization Mediated by Tobacco PLC3 Activity and Endocytic Membrane Recycling PLANT CELL, December 1, 2006; 18(12): 3519 - 3534. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Poeckel, L. Tausch, S. George, J. Jauch, and O. Werz 3-O-Acetyl-11-keto-boswellic Acid Decreases Basal Intracellular Ca2+ Levels and Inhibits Agonist-Induced Ca2+ Mobilization and Mitogen-Activated Protein Kinase Activation in Human Monocytic Cells J. Pharmacol. Exp. Ther., January 1, 2006; 316(1): 224 - 232. [Abstract] [Full Text] [PDF]
|
|
 |
 |
 |
|
 |
 |
 |
