This project is based on the hypothesis that oxygenation of polyunsaturated fatty acids (PUFAs) in the brain by cytochrome P450 (CYP) enzymes plays an important role in the regulation of cerebral blood flow and inflammation. We have previously focused on the NADPH-dependent metabolism of arachidonate (AA) to epoxyeicosatrienoates (EETs) and 20-hydroxyeicosatetraenoate (20-HETE), and the involvement of these metabolites in control of cerebral vascular tone through their action on Ca2+activated K+ channels. In this renewal, we will continue to study the functional significance of NADPH-dependent CYP metabolism of AA, however, we will extend these studies to also include other PUFAs, such as docosahexaenoate (DHA) and eicosapentaenoate (EPA), as well as the potent inflammatory mediator leukotriene B4 (LTB4). In our preliminary studies, we have identified CYP enzymes that are expressed in the brain and are capable of metabolizing PUFAs into vasoactive metabolites. These enzymes belong to two different subfamilies, i.e. the CYP4F and CYP4X. Initial data suggests that enzymes of the CYP4F subfamily can oxygenate AA and LTB4 into co-side chain hydroxy metabolites, and DHA and EPA into epoxy metabolites. CYP4X1 is a novel rat enzyme, cloned in our laboratory, which is highly and predominantly expressed in specific neurons and cerebral vascular endothelial cells. Preliminary results show that the CYP4X1 protein is highly conserved between different species and that recombinant CYP4X1 is capable of converting AA into EETs. However, the functional consequences of CYP4F and CYP4X1 catalyzed oxygenation of PUFAs in the brain are unknown.
Specific Aim 1 : will characterize the expression and catalytic properties of CYP4F isoforms in the brain, and to characterize the biological action of CYP4F oxygenated metabolites of PUFAs.
Specific Aim 2 : will determine the functional significance of LTB4 metabolism by CYP4F enzymes in the brain.
Specific Aim 3 : will characterize the expression and catalytic properties of human, mouse and rat CYP4X1 and define the biological activities of CYP4Xl-generated metabolites. This project will increase our understanding about the function of newly identified CYP isoforms in the brain and the actions of metabolites of PUFAs other than AA in the control of inflammation and cerebral blood flow.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Program Projects (P01)
Project #
5P01HL059996-07
Application #
7312495
Study Section
Heart, Lung, and Blood Initial Review Group (HLBP)
Project Start
Project End
Budget Start
2006-02-01
Budget End
2007-01-31
Support Year
7
Fiscal Year
2006
Total Cost
$499,764
Indirect Cost
Name
Medical College of Wisconsin
Department
Type
DUNS #
937639060
City
Milwaukee
State
WI
Country
United States
Zip Code
53226
Gebremedhin, Debebe; Zhang, David X; Carver, Koryn A et al. (2016) Expression of CYP 4A ?-hydroxylase and formation of 20-hydroxyeicosatetreanoic acid (20-HETE) in cultured rat brain astrocytes. Prostaglandins Other Lipid Mediat 124:16-26
Pabbidi, Mallikarjuna R; Mazur, Olga; Fan, Fan et al. (2014) Enhanced large conductance K+ channel activity contributes to the impaired myogenic response in the cerebral vasculature of Fawn Hooded Hypertensive rats. Am J Physiol Heart Circ Physiol 306:H989-H1000
Gebremedhin, Debebe; Gopalakrishnan, Sandeep; Harder, David R (2014) Endogenous events modulating myogenic regulation of cerebrovascular function. Curr Vasc Pharmacol 12:810-7
Carver, Koryn A; Lourim, David; Tryba, Andrew K et al. (2014) Rhythmic expression of cytochrome P450 epoxygenases CYP4x1 and CYP2c11 in the rat brain and vasculature. Am J Physiol Cell Physiol 307:C989-98
Gebremedhin, Debebe; Terashvili, Maia; Wickramasekera, Nadi et al. (2013) Redox signaling via oxidative inactivation of PTEN modulates pressure-dependent myogenic tone in rat middle cerebral arteries. PLoS One 8:e68498
Wickramasekera, Nadi T; Gebremedhin, Debebe; Carver, Koryn A et al. (2013) Role of dual-specificity protein phosphatase-5 in modulating the myogenic response in rat cerebral arteries. J Appl Physiol 114:252-61
Yang, Zeng-Jin; Carter, Erin L; Kibler, Kathleen K et al. (2012) Attenuation of neonatal ischemic brain damage using a 20-HETE synthesis inhibitor. J Neurochem 121:168-79
Renic, Marija; Kumar, Suresh N; Gebremedhin, Debebe et al. (2012) Protective effect of 20-HETE inhibition in a model of oxygen-glucose deprivation in hippocampal slice cultures. Am J Physiol Heart Circ Physiol 302:H1285-93
Liu, Xiaoguang; Li, Chunyuan; Falck, John R et al. (2012) Relative contribution of cyclooxygenases, epoxyeicosatrienoic acids, and pH to the cerebral blood flow response to vibrissal stimulation. Am J Physiol Heart Circ Physiol 302:H1075-85
Terashvili, M; Sarkar, P; Nostrand, M V et al. (2012) The protective effect of astrocyte-derived 14,15-epoxyeicosatrienoic acid on hydrogen peroxide-induced cell injury in astrocyte-dopaminergic neuronal cell line co-culture. Neuroscience 223:68-76

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