Expression and catalytic activity of mouse leukotriene B-4 omega-hydroxylase, CYP4F14

We have isolated a cDNA for a mouse leukotriene B-4 omega -hydroxylase, CYP 4F14. The cDNA encoded a protein with 524 amino acids, whose sequence simil arity is 95% that of rat CYP4F1, The microsomes from yeast cells transfecte d with CYP4F14 expression vector showed 0.1 nmol P450/mg protein and cataly zed omega -hydroxylations of leukotriene B-4, 6-trans-leukotriene B-4, lipo xin A(4), prostaglandin A(1), and several hydroxyeicosatetraeonic acids (HE TEs), with 8-HETE being the most active substrate. In contrast, no activity was detected toward lipoxin B-4, laurate, and arachidonate. The mRNA for C YP4F14 had three different 5' untranslated sequences. Analysis of the CYP4F 14 gene showed that two exon I sequences with different transcription start sites are located in the gene, and two splicing signals on the 3' end of i ntron I are alternatively used. The mRNA for this P450 was detected only in the liver by Northern blot analysis, whereas a small amount of the mRNA wa s detected in the brain using RT-PCR, Administration of clofibrate had no e ffect on microsomal 6-trans-leukotriene B-4 omega -hydroxylase activity, bu t resulted in a marked reduction in the content of mRNA for this P450 in th e liver. These findings indicate that CYP4F14 is very similar to CYP4F1 exc ept for its expression in the brain and 5' untranslated sequences. (C) 2000 Academic Press.