Cytochrome P450 4F8 is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

that in humans is encoded by the ''CYP4F8''

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

Function

This gene, CYP4F8, encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. This protein localizes to the endoplasmic reticulum and functions as a 19-hydroxylase of the

arachidonic acid Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega−6 fatty acid 20:4(ω−6), or 20:4(5,8,11,14). It is a precursor in the formation of leukotrienes, prostaglandins, and thromboxanes. Together with omega−3 fatty acids an ...

metabolite,

prostaglandin H2 Prostaglandin H2 (PGH2), or prostaglandin H2 (PGH2), is a type of prostaglandin and a precursor for many other biologically significant molecules. It is synthesized from arachidonic acid in a reaction catalyzed by a cyclooxygenase enzyme. The con ...

(PGH2) and the Dihomo-γ-linolenic acid metabolite PGH1 in

seminal vesicles The seminal vesicles (also called vesicular glands or seminal glands) are a pair of convoluted tubular accessory glands that lie behind the urinary bladder of male mammals. They secrete fluid that largely composes the semen. The vesicles are 5 ...

. This gene is part of a cluster of cytochrome P450 genes on chromosome 19. Another member of this family, CYP4F3, is approximately 18 kb away. In addition to seminal vesicles, CYP4F8 is expressed in kidney, prostate, epidermis, and corneal epithelium, and its

mRNA In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein. mRNA is ...

has been found in retina; CYP4F8 is also greatly up-regulated in psoriatic skin. In addition to its ability to metabolize and presumably thereby to inactivate or reduce the activity of PGH2 and PGH1, CYP4F8 adds

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

residues to carbons 18 and 19 of

and Dihomo-γ-linolenic acid, CYP458 possesses

epoxygenase Epoxygenases are a set of membrane-bound, heme-containing cytochrome P450 (CYP450 or just CYP) enzymes that metabolize polyunsaturated fatty acids (PUFAs) to epoxide products that have a range of biological activities. The most thoroughly-studi ...

activity in that it metabolizes the

omega-3 fatty acid Omega−3 fatty acids, also called omega−3 oils, ω−3 fatty acids or ''n''−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond three atoms away from the terminal methyl group in their ...

docosahexaenoic acid Docosahexaenoic acid (DHA) is an omega−3 fatty acid that is an important component of the human brain, cerebral cortex, skin, and retina. It is given the fatty acid notation 22:6(''n''−3). It can be synthesized from alpha-linolenic acid or ...

(DHA) and

eicosapentaenoic acid Eicosapentaenoic acid (EPA; also icosapentaenoic acid) is an omega−3 fatty acid. In physiological literature, it is given the name 20:5(''n''−3). It also has the trivial name timnodonic acid. In chemical structure, EPA is a carboxylic acid wi ...

, (EPA) to their corresponding

epoxide In organic chemistry, an epoxide is a cyclic ether, where the ether forms a three-atom ring: two atoms of carbon and one atom of oxygen. This triangular structure has substantial ring strain, making epoxides highly reactive, more so than other ...

s, the

epoxydocosapentaenoic acid Epoxide docosapentaenoic acids (epoxydocosapentaenoic acids, EDPs, or EpDPEs) are metabolites of the 22-carbon straight-chain omega-3 fatty acid, docosahexaenoic acid (DHA). Cell types that express certain cytochrome P450 (CYP) epoxygenases meta ...

s (EDPs) and

epoxyeicosatetraenoic acid Epoxyeicosatetraenoic acids (EEQs or EpETEs) are a set of biologically active epoxides that various cell types make by metabolizing the omega 3 fatty acid, eicosapentaenoic acid (EPA), with certain cytochrome P450 epoxygenases. These epoxygenase ...

s (EEQs), respectively. The enzyme metabolizes DHA primarily to 19''R'',20''S''-epoxyeicosapentaenoic acid and 19''S'',20''R''-epoxyeicosapentaenoic acid isomers (termed 19,20-EDP) and EPA primarily to 17''R'',18''S''-eicosatetraenoic acid and 17''S'',18''R''-eicosatetraenoic acid isomers (termed 17,18-EEQ). 19-HETE is an inhibitor of 20-HETE, a broadly active signaling molecule which acts to constrict

arteriole An arteriole is a small-diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillary, capillaries. Arterioles have vascular smooth muscle, muscular walls (usually only one to two layers of smoo ...

s, elevate blood pressure, promote

inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...

responses, and stimulates the growth of various types of tumor cells; however the in vivo ability and significance of 19-HETE in inhibiting 20-HETE has not been demonstrated (see 20-Hydroxyeicosatetraenoic acid). The EDPs (see

Epoxydocosapentaenoic acid Epoxide docosapentaenoic acids (epoxydocosapentaenoic acids, EDPs, or EpDPEs) are metabolites of the 22-carbon straight-chain omega-3 fatty acid, docosahexaenoic acid (DHA). Cell types that express certain cytochrome P450 (CYP) epoxygenases meta ...

) and EEQs (see

) have a broad range of activities. In various animal models and in vitro studies on animal and human tissues, they decrease hypertension and pain perception; suppress inflammation; inhibit

angiogenesis Angiogenesis is the physiological process through which new blood vessels form from pre-existing vessels, formed in the earlier stage of vasculogenesis. Angiogenesis continues the growth of the vasculature mainly by processes of sprouting and ...

, endothelial cell migration and endothelial cell proliferation; and inhibit the growth and metastasis of human breast and prostate cancer cell lines. It is suggested that the EDP and EEQ metabolites function in humans as they do in animal models and that, as products of the

s, DHA acid and EPA, the EDP and EEQ metabolites contribute to many of the beneficial effects attributed to dietary omega-3 fatty acids. EDP and EEQ metabolites are short-lived, being inactivated within seconds or minutes of formation by

epoxide hydrolase Epoxide hydrolases (EHs), also known as epoxide hydratases, are enzymes that metabolize compounds that contain an epoxide residue; they convert this residue to two hydroxyl residues through an epoxide hydrolysis reaction to form diol products. ...

s, particularly

soluble epoxide hydrolase Soluble epoxide hydrolase (sEH) is a bifunctional enzyme that in humans is encoded by the ''EPHX2'' gene. sEH is a member of the epoxide hydrolase family. This enzyme, found in both the cytosol and peroxisomes, binds to specific epoxides and con ...

, and therefore act locally. CYP4F8 has little activity in omega-hydroxylating

leukotriene B4 Leukotriene B4 (LTB4) is a leukotriene involved in inflammation. It has been shown to promote insulin resistance in obese mice. Biochemistry LTB4 is a leukotriene involved in inflammation. It is produced from leukocytes in response to inflammato ...

prostaglandin D2 Prostaglandin D2 (or PGD2) is a prostaglandin that binds to the receptor PTGDR (DP1), as well as CRTH2 (DP2). It is a major prostaglandin produced by mast cells – recruits Th2 cells, eosinophils, and basophils. In mammalian organs, large a ...

prostaglandin E2 Prostaglandin E2 (PGE2), also known as dinoprostone, is a naturally occurring prostaglandin with oxytocic properties that is used as a medication. Dinoprostone is used in labor induction, bleeding after delivery, termination of pregnanc ...

prostaglandin E1 Prostaglandin E1 (PGE1) is a naturally occurring prostaglandin with various medical uses. Alprostadil and misoprostol are synthetic forms of prostaglandin E1 used as medications. Lubiprostone, a derivative of prostaglandin E1, is also used as ...

, or

prostaglandin F2 Prostaglandin F2α (PGF2α in prostanoid nomenclature), pharmaceutically termed dinoprost, is a naturally occurring prostaglandin used in medicine to induce labor and as an abortifacient. Prostaglandins are lipids throughout the entire body that ...

. The fatty acid metabolizing activity, including the ability to form epoxides, of CYP4F8 is very similar to that of

CYP4F12 Cytochrome P450 4F12 is a protein that, in humans, is encoded by the ''CYP4F12'' gene. Gene family The ''CYP4F12'' gene encodes a member of the cytochrome P450 superfamily of enzymes. It is located within a cluster of P450 genes on chromosome ...

. However, it and CYP4F12 are not regarded as being major contributors in forming the cited epoxides in humans although they might do so in tissues where they are highly expressed.

Function

References

Further reading