A 12R-lipoxygenase in human skin: mechanistic evidence, molecular cloning, and expression.

Boeglin WE, Kim RB, Brash AR
Proc Natl Acad Sci U S A. 1998 95 (12): 6744-9

PMID: 9618483 · PMCID: PMC22619 · DOI:10.1073/pnas.95.12.6744

A recognized feature of psoriasis and other proliferative dermatoses is accumulation in the skin of the unusual arachidonic acid metabolite, 12R-hydroxyeicosatetraenoic acid (12R-HETE). This hydroxy fatty acid is opposite in chirality to the product of the well-known 12S-lipoxygenase and heretofore in mammals is known only as a product of cytochrome P450s. Here we provide mechanistic evidence for a lipoxygenase route to 12R-HETE in human psoriatic tissue and describe a 12R-lipoxygenase that can account for the biosynthesis. Initially we demonstrated retention of the C-12 deuterium of octadeuterated arachidonic acid in its conversion to 12R-HETE in incubations of psoriatic scales, indicating the end product is not formed by isomerization from 12S-H(P)ETE via the 12-keto derivative. Secondly, analysis of product formed from [10R-3H] and [10S-3H]-labeled arachidonic acids revealed that 12R-HETE synthesis is associated with stereospecific removal of the pro-R hydrogen from the 10-carbon of arachidonate. This result is compatible with 12R-lipoxygenase-catalyzed formation of 12R-HETE and not with a P450-catalyzed route to 12R-HETE in psoriatic scales. We cloned a lipoxygenase from human keratinocytes; the cDNA and deduced amino acid sequences share 98% 12R in configuration. The 12R-lipoxygenase cDNA is detectable by PCR in psoriatic scales and as a 2.5-kilobase mRNA by Northern analysis of keratinocytes. Identification of this enzyme extends the known distribution of R-lipoxygenases to humans and presents an additional target for potential therapeutic interventions in psoriasis.

MeSH Terms (14)

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid Amino Acid Sequence Arachidonate 12-Lipoxygenase Base Sequence Cloning, Molecular DNA, Complementary Gene Expression Regulation Gene Transfer Techniques HeLa Cells Humans Molecular Sequence Data Psoriasis Sequence Analysis Skin

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