12(S)-Hydroxyheptadeca-5Z, 8E, 10E-trienoic acid is a natural ligand for leukotriene B4 receptor 2.
Activated blood platelets and macrophages metabolize prostaglandin H(2) into thromboxane A(2) and 12(S)-hydroxyheptadeca-5Z, 8E, 10E-trienoic acid (12-HHT) in an equimolar ratio through the action of thromboxane synthase. Although it has been shown that 12-HHT is abundant in tissues and bodily fluids, this compound has long been viewed as a by-product lacking any specific function. We show that 12-HHT is a natural ligand for leukotriene B(4) (LTB(4)) receptor-2 (BLT2), a G protein-coupled receptor that was originally identified as a low-affinity receptor for LTB(4). BLT2 agonistic activity in lipid fractions from rat small intestine was identified as 12-HHT using high-performance liquid chromatography and mass spectrometry. Exogenously expressed BLT2 in mammalian cells was activated by synthetic 12-HHT, as assessed by guanosine 5'-O-(3-thio) triphosphate binding, the activation of intracellular signaling pathways, and chemotaxis assay. Displacement analysis using [(3)H]LTB(4) showed that 12-HHT binds to BLT2 with a higher affinity than LTB(4). Lipid extracts from cyclooxygenase 1-deficient mice failed to activate BLT2. Bone marrow-derived mast cells (BMMCs) isolated from wild-type mice migrated toward a low concentration of 12-HHT, whereas BMMCs from BLT2-deficient mice did not. We conclude that 12-HHT is a natural lipid agonist of BLT2 in vivo and induces chemotaxis of mast cells.
Okuno
Toshiaki
T
Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
Iizuka
Yoshiko
Y
Okazaki
Hiroshi
H
Yokomizo
Takehiko
T
Taguchi
Ryo
R
Shimizu
Takao
T
D000096:Acetone; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D051545:Cyclooxygenase 1 / Q000172:deficiency; D005231:Fatty Acids, Unsaturated / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism; D008024:Ligands; D008055:Lipids / Q000737:chemistry / Q000302:isolation & purification; D013058:Mass Spectrometry; D051379:Mice; D051381:Rats; D018102:Receptors, Leukotriene B4 / Q000819:agonists / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D012995:Solubility / Q000187:drug effects
D005231:Fatty Acids, Unsaturated; D008024:Ligands; D008055:Lipids; C412867:Ltb4r2 protein, mouse; D018102:Receptors, Leukotriene B4; D000096:Acetone; C008033:12-hydroxy-5,8,10-heptadecatrienoic acid; D051545:Cyclooxygenase 1; D019204:GTP-Binding Proteins