Cytochrome P450s catalyze the metabolism of drugs and natural products, resulting in either the inactivation or activation of their biological properties. The class 4 cytochromes catalyze the oxidation of leukotrienes, prostaglandins, and saturated fatty acids. The 4F subfamily members both activate and inactivate eicosanoids for biological function. Humans express CYP4F2 and CYP4F3. Both genes contains 14 exons and 13 introns. Myeloid cells express one form of the CYP4F3 gene(A) that incorporates exon 4, whereas adult and fetal liver express another form of the gene, CYP4F3B, that incorporates exon 3. The known form of CYP4F2 incorporates exon 3. CYP4F3A utilizes LTB4, but not arachidonic acid as a substrate, resulting in the formation of 20-OH LTB4 and the inactivation of this molecule for biological activity. CYP4F3B, has a KM for LTB4 that is over 20- times higher than that of CYP4F3A. By analogy with CYP4F2, which shares 93 percent identity with CYP4F3B, CYP4F3A and CYP4F3B likely possess distinct substrate specificity, with CYP4F3A inactivating LTB4, and CYP4F3B generating the bioactive metabolite 20-HETE from arachidonic acid as its preferred reaction. We propose that the biological roles of CYP4F3 and CYP4F2 are determined by the coordinated tissue-specific expression and splicing of the respective genes, and mRNAs. The goal of this proposal is to determine how CYP4F3 and CYP4F2 regulate the formation of 20-HETE and the inactivation of LTB4 in different tissues. In the first specific aim the contribution of CYP4F3B and CYP4F2 to 20-HETE formation in liver and kidney will be determined by the use of isoform specific antibodies, and semiquantititative PCR. In the second specific aim, the structural basis for the change in substrate specificity and KM between CYP4F3A and CYP4F3B will be determined using a combination of site specific mutagenesis and computer modeling.
In specific aim 3, the of basis of cell-specific expression of CYP4F3 and CYP4F2 will be determined. Luciferase reporter constructs, DNase I footprinting, EMSA, and mutagenesis will identify promoter elements determining the expression of CYP4F3 in hematopoetic and liver cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM061823-03
Application #
6520316
Study Section
Pharmacology A Study Section (PHRA)
Program Officer
Preusch, Peter C
Project Start
2000-07-01
Project End
2004-06-30
Budget Start
2002-07-01
Budget End
2003-06-30
Support Year
3
Fiscal Year
2002
Total Cost
$328,962
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
Mandal, Asim K; Jones, Phillip B; Bair, Angela M et al. (2008) The nuclear membrane organization of leukotriene synthesis. Proc Natl Acad Sci U S A 105:20434-9
Christmas, Peter; Tolentino, Karine; Primo, Valeria et al. (2006) Cytochrome P-450 4F18 is the leukotriene B4 omega-1/omega-2 hydroxylase in mouse polymorphonuclear leukocytes: identification as the functional orthologue of human polymorphonuclear leukocyte CYP4F3A in the down-regulation of responses to LTB4. J Biol Chem 281:7189-96
Locuson, Charles W; Wahlstrom, Jan L (2005) Three-dimensional quantitative structure-activity relationship analysis of cytochromes p450: effect of incorporating higher-affinity ligands and potential new applications. Drug Metab Dispos 33:873-8
Mandal, Asim K; Skoch, Jesse; Bacskai, Brian J et al. (2004) The membrane organization of leukotriene synthesis. Proc Natl Acad Sci U S A 101:6587-92
Soberman, Roy J (2003) The expanding network of redox signaling: new observations, complexities, and perspectives. J Clin Invest 111:571-4
Soberman, Roy J; Christmas, Peter (2003) The organization and consequences of eicosanoid signaling. J Clin Invest 111:1107-13
Rock, Dan A; Perkins, Brandon N S; Wahlstrom, Jan et al. (2003) A method for determining two substrates binding in the same active site of cytochrome P450BM3: an explanation of high energy omega product formation. Arch Biochem Biophys 416:9-16
Christmas, Peter; Carlesso, Nadia; Shang, Haibo et al. (2003) Myeloid expression of cytochrome P450 4F3 is determined by a lineage-specific alternative promoter. J Biol Chem 278:25133-42
Christmas, Peter; Weber, Brittany M; McKee, Mary et al. (2002) Membrane localization and topology of leukotriene C4 synthase. J Biol Chem 277:28902-8
Fitzpatrick, F A; Soberman, R (2001) Regulated formation of eicosanoids. J Clin Invest 107:1347-51

Showing the most recent 10 out of 12 publications