5-hydroxyicosatetraenoate stimulates neutrophils by a stereospecific, G protein-linked mechanism.
We examined how 5-hydroxyicosatetraenoate (5-HETE) activates human neutrophils (PMN). 5-HETE stimulates PMN to mobilize Ca2+ but has little effect on degranulation or superoxide anion production. It nonetheless stereospecifically induced these responses in cells primed with tumor necrosis factor-alpha and likewise induced PMN plasma membranes to bind 35S-labeled guanosine 5'-O-(thiotriphosphate) (GTP gamma S) and phosphohydrolyze [gamma-32P]GTP. Pertussis toxin blocked GTP gamma S binding responses. Scatchard analyses of GTP gamma S binding data indicated that 5-HETE raised the Ka of high affinity GTP gamma S binding sites without altering these sites' numbers or the parameters of low affinity GTP gamma S binding. Since N-formyl-Met-Leu-Phe, platelet-activating factor, and leukotriene (LT) B4 have these same bioactions, receptors for the latter agents might mediate responses to 5-HETE. However, 5-HETE desensitized degranulation responses to itself but not to the receptor agonists, the receptor agonists desensitized to themselves but not 5-HETE, and a LTB4 antagonist inhibited LTB4 but not 5-HETE in all assays. Finally, PMN and their membranes took up [3H] 5-HETE at 4 or 37 degrees C but, at both temperatures, also acylated the radiolabel into glycerolipids. Acylation nullified assessment of 5-HETE binding and questions reports that measure the cell binding, but not metabolism, of various HETEs. Our studies thus indicate 5-HETE acts by a down-regulatable, G protein-linked mechanism and represent the best available evidence that 5-HETE does not operate through, for example, LTB4 receptors.
Department of Medicine, Wake Forest University Medical Center, Winston-Salem, North Carolina 27157.
J T
JT
O'Flaherty
A G
AG
Rossi
D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism / Q000494:pharmacology*; D007975:Leukotriene B4 / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D010972:Platelet Activating Factor / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D006893:Hydroxyeicosatetraenoic Acids; D010972:Platelet Activating Factor; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D007975:Leukotriene B4; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019204:GTP-Binding Proteins; D002118:Calcium