Leukotriene synthesis in U937 cells expressing recombinant 5-lipoxygenase.
The U937 human promyelocytic cell line does not express 5-lipoxygenase, but does express 5-lipoxygenase-activating protein (FLAP). U937 cells do not synthesize leukotrienes after stimulation by calcium ionophore A23187. Dimethyl sulfoxide (DMSO) differentiation of U937 cells, towards a more mature monocyte-macrophage lineage, induces the expression of FLAP but not 5-lipoxygenase. These DMSO-differentiated U937 cells also lack the ability to synthesize leukotrienes. We infected viral RNA coding for 5-lipoxygenase into U937 cells using a retroviral vector and measured the synthesis of 5-lipoxygenase, FLAP, leukotrienes and 5-hydroxyeicosatetraenoic acid (5-HETE) by these cells after stimulation with A23187. Undifferentiated U937 cells infected with 5-lipoxygenase RNA expressed 5-lipoxygenase and FLAP but neither leukotrienes nor 5-HETE were detected after these cells were stimulated with A23187. Exposure of the 5-lipoxygenase-infected U937 cells to DMSO increased the expression of 5-lipoxygenase and FLAP, and these cells produced leukotrienes and 5-HETE in response to A23187. The synthesis of these products was inhibited by MK-886, a compound which specifically binds to FLAP.
Kargman
S
S
Department of Pharmacology, Merck Frosst Centre for Therapeutic Research, Pointe Claire-Dorval, Quebec, Canada.
Rousseau
P
P
Reid
G K
GK
Rouzer
C A
CA
Mancini
J A
JA
Rands
E
E
Dixon
R A
RA
Diehl
R E
RE
Léveillé
C
C
Nathaniel
D
D
D058927:5-Lipoxygenase-Activating Proteins; D001094:Arachidonate 5-Lipoxygenase / Q000096:biosynthesis*; D002352:Carrier Proteins / Q000096:biosynthesis; D002454:Cell Differentiation / Q000187:drug effects; D004121:Dimethyl Sulfoxide; D005822:Genetic Vectors; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000096:biosynthesis*; D015289:Leukotrienes / Q000096:biosynthesis*; D008565:Membrane Proteins / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis; D012190:Retroviridae / Q000235:genetics; D014407:Tumor Cells, Cultured
D058927:5-Lipoxygenase-Activating Proteins; C548592:ALOX5AP protein, human; D002352:Carrier Proteins; D006893:Hydroxyeicosatetraenoic Acids; D015289:Leukotrienes; D008565:Membrane Proteins; D011994:Recombinant Proteins; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; D001094:Arachidonate 5-Lipoxygenase; D004121:Dimethyl Sulfoxide