Guanylyl cyclase and protein kinase G mediate nitric oxide suppression of 5-lipoxygenase metabolism in rat alveolar macrophages.
We have previously demonstrated that exogenous nitric oxide (NO) directly inhibits alveolar macrophage (AM) cell-free activity of the enzyme 5-lipoxygenase (5-LO), thereby inhibiting metabolism of arachidonic acid to the important proinflammatory lipid mediators, leukotrienes (LT). Here, we explored the possibility that NO indirectly inhibited AM LT synthesis via activation of soluble guanylyl cyclase (sGC) in rat AM. The selective sGC inhibitor, LY83583, abrogated the suppression of cellular LT synthesis elicited by either exogenous or endogenous NO. A non-NO-dependent activator of sGC, YC-1, also inhibited macrophage LT synthesis. We next determined if sGC-mediated suppression of AM LT synthesis was dependent on protein kinase G (cGK). The selective cGK inhibitor, KT5823, reversed the suppression of cellular 5-LO metabolism following treatment with exogenous NO and YC-1. cGK1 activation resulted in phosphorylation of 5-LO. In contrast to peritoneal macrophages, AM exhibited localization of sGC, cGK1 and cGKII to the cell nucleus. In summary, in addition to its direct effects, NO-induced suppression of 5-LO action can be mediated indirectly through activation of the sGC and cGK pathways in AM. The nuclear localization of enzymes sGC, CGK1 and cGKII in the AM, which also demonstrates preferential nuclear 5-LO expression, may confer tighter regulation of LT synthesis.
Coffey
Michael J
MJ
Division of Pulmonary and Critical Care Medicine, University of Michigan Medical Center, 1150 N. Medical Center Drive, Ann Arbor, MI 48109, USA. coffeym@umich.edu
Phare
Susan M
SM
Luo
Ming
M
Peters-Golden
Marc
M
D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D002227:Carbazoles / Q000494:pharmacology; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007150:Immunohistochemistry; D008070:Lipopolysaccharides / Q000494:pharmacology; D016676:Macrophages, Alveolar / Q000187:drug effects* / Q000201:enzymology; D009569:Nitric Oxide / Q000502:physiology*; D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology
D000634:Aminoquinolines; D002227:Carbazoles; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; C073601:KT 5823; D009569:Nitric Oxide; C041715:6-anilino-5,8-quinolinedione; D001094:Arachidonate 5-Lipoxygenase; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase