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Biosynthesis of 14,15‐Hepoxilins in Human L1236 Hodgkin Lymphoma Cells and Eosinophils
Author(s) -
Brunnström Åsa,
Hamberg Mats,
Griffiths William J.,
Mannervik Bengt,
Claesson HansErik
Publication year - 2011
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-010-3485-1
Subject(s) - chemistry , arachidonic acid , incubation , biosynthesis , stereochemistry , electrospray ionization , tandem mass spectrometry , lipoxygenase , biochemistry , enzyme , mass spectrometry , chromatography
Hepoxilins are epoxy alcohols synthesized through the 12‐lipoxygenase (12‐LO) pathway in animal cells. The epidermis is the principal source of hepoxilins in humans. Here we report on the formation of novel hepoxilin regioisomers formed by the 15‐LO pathway in human cells. The Hodgkin lymphoma cell line L1236 possesses high 15‐lipoxygenase‐1 (15‐LO‐1) activity and incubation of L1236 cells with arachidonic acid led to the formation of 11( S )‐hydroxy‐14( S ),15( S )‐epoxy 5( Z ),8( Z ),12( E ) eicosatrienoic acid (14,15‐HxA 3 11( S )) and 13( R )‐hydroxy‐14( S ),15( S )‐epoxy 5( Z ),8( Z ),11( Z ) eicosatrienoic acid (14,15‐HxB 3 13 ( R )). In addition, two hitherto unidentified products were detected and these products were collected and analyzed by positive ion electrospray tandem mass spectrometry. These metabolites were identified as 11( S ),15( S )‐dihydroxy‐14( R )‐glutathionyl‐5( Z ),8( Z ),12( E )‐eicosatrienoic acid (14,15‐HxA 3 ‐C) and 11( S ),15( S )‐dihydroxy‐14( R )‐cysteinyl‐glycyl‐5( Z ),8( Z ),12( E )‐eicosatrienoic acid (14,15‐HxA 3 ‐D). Incubation of L1236 cells with synthetic 14,15‐HxA 3 11( S ) also led to the formation of 14,15‐HxA 3 ‐C and 14,15‐HxA 3 ‐D. Several soluble glutathione transferases, in particular GST M1‐1 and GST P1‐1, were found to catalyze the conversion of 14,15‐HxA 3 to 14,15‐HxA 3 ‐C. L1236 cells produced approximately twice as much eoxins as cysteinyl‐containing hepoxilins upon stimulation with arachidonic acid. Human eosinophils, nasal polyps and dendritic cells selectively formed 14,15‐HxA 3 11( S ) and 14,15‐HxB 3 13( R ) stereoisomers, but not cysteinyl‐containing hepoxilins, after stimulation with arachidonic acid. Furthermore, purified recombinant 15‐LO‐1 alone catalyzed the conversion of arachidonic acid to 14,15‐HxA 3 11( S ) and 14,15‐HxB 3 13( R ), showing that human 15‐LO‐1 possesses intrinsic 14,15‐hepoxilin synthase activity.