Human 12(R)-lipoxygenase and the mouse ortholog - Molecular cloning, expression, and gene chromosomal assignment

Expressed sequence tag information was used to clone the full-length sequen ce for a new human lipoxygenase from the B cell line CCL-156, A related mou se sequence with 83% nucleotide identity to the human sequence was also clo ned. The human lipoxygenase, when expressed via the baculovirus/insect cell system produced an approximate to 80-kDa protein capable of metabolizing a rachidonic acid to a product identified as 12-hydroxyeicosatetraenoic acid by mass spectrometry. Using chiral phase-high performance liquid chromatogr aphy, the product was identified as >98% 12(R)-hydroxyeicosatetraenoic acid as opposed to the S-stereoisomer formed by all other known mammalian lipox ygenases, The single copy human 12(R)-lipoxygenase gene was localized to th e chromosome 17p13 region, the locus where most other lipoxygenase genes ar e known to reside. By reverse transcription-polymerase chain reaction, but not by Northern blot, analysis the 12(R)-lipoxygenase mRNA was detected in B cells and adult skin. However, the related mouse lipoxygenase mRNA was hi ghly expressed in epidermis of newborn mice and to a lesser extent in adult brain cortex, By in situ hybridization the mouse lipoxygenase gene was dem onstrated to be temporally and spatially regulated during embryogenesis, Ex pression was induced at embryonic day 15.5 in epidermis, nasal epithelium, and surface of the tongue. These results broaden the mammalian lipoxygenase family to include a 12(R)-lipoxygenase whose biological function remains t o be determined.