Cytochrome P-450 Metabolites Mediate Norepinephrine-Induced Mitogenic Signaling

Abstract

Abstract-Norepmephrme (NE) stimulates release of arachldomc acid (AA) f rom tissue lipids m blood vessels, which 1s metabolized via cyclooxygenase, hpoxygenase (LO), and cytochrome P-450 (CYP-450) pathways to blologcally active products Moreover, NE and AA have been shown to stimulate prohferatlon of vascular smooth muscle cells (VSMCs) of rat aorta The purpose of this study was to determme the possible contrlbutlon of AA and Its metabohtes to NE-Induced mltogenesls m VSMCs of rat aorta and the underlying mechanism of their actions NE (0 1 to 10 pmol/L) increased DNA synthesis as measured by [3H] Actlvatlon of a-aderenerglc receptors with NE has also been reported to stimulate AA release m a Ca2+/calmodulm-dependent manner via actlvatlon of cPLA, U" Recently, we have shown that NE stimulates cPLA, and AA release by activating Cazf/calmoduhn-dependent kmase II " AA and the products of its metabolism have been shown to stimulate growth m many cell types including VSMCs '8-z2 Moreover AA and LO metabohtes stimulate MAP kmase activity 22 These observatlons and the recent finding that NE-induced hyperplasla IS dependent on MAP kmase actlvatlon""' have led us to hypothesize that NE-induced VSMC prohferatlon 1s mediated by AA and/or Its metabohtes via MEK actlvatlon To test this hypothesis, we have mvestlgated the effect of NE and AA on rat aortlc smooth muscle cell prohferatlon, measured by

Norepinephrine-Induced Stimulation of p38 Mitogen-Activated Protein Kinase Is Mediated by Arachidonic Acid Metabolites Generated by Activation of Cytosolic Phospholipase A2 in Vascular Smooth Muscle Cells

“…In VSMC, AA is metabolized to prostaglandins by cyclooxygenase (COX), to 5(S)-hydroxyeicosatetraenoic acid (HETE), 12(S)-HETE, and 15(S)-HETE by lipoxygenase (LO) and to 20-HETE by NADPH-dependent cytochrome P450 (P450) (Larrue et al, 1983;Nebigil and Malik, 1990;Muthalif et al, 1998a). The LO and P450 metabolites, through activation of the Ras/ mitogen-activated protein kinase kinase/ERK mitogen-activated protein kinase (MAPK) pathway, mediate NE-induced VSMC proliferation (Uddin et al, 1998).…”

20-Hydroxyeicosatetraenoic Acid Mediates Angiotensin II–Induced Phospholipase D Activation in Vascular Smooth Muscle Cells

“…[1][2][3] Ang II produces these biological actions by generating lipid mediators, including arachidonic acid and its metabolites, consequent to the activation of phospholipase A 2 (PLA 2 ), phospholipase C, and phospholipase D (PLD) and by producing superoxide and hydrogen peroxide. 4,5 The activation of PLA 2 releases arachidonic acid directly from phospholipids, whereas PLD catalyzes the hydrolysis of phosphatidylcholine into choline and phosphatidic acid.…”

ANG II-induced neointimal growth is mediated via cPLA2- and PLD2-activated Akt in balloon-injured rat carotid artery

“…Moreover, in neointimal smooth muscle cells, CYP1A1 expression level is high (12), and CYPA1 antisense inhibits ANG II-and AA-induced increase in neointimal growth in injured rat carotid arteries (49), suggesting that CYP4A metabolites of AA are also involved in neointimal growth (49). An AA metabolite of CYP4A1, 20-HETE, has been shown to promote VSMC proliferation (45), increase Akt phosphorylation (21), and stimulate neointimal growth in injured carotid arteries (49).…”

“…Arachidonic acid (AA) is the main fatty acid generated by PLA 2 activation, and it is metabolized by cyclooxygenase (COX), lipoxygenase (LO), and cytochrome P-450 (CYP) enzymes into various biologically active products (3). The inhibition of 85-kDa cPLA 2 is associated with reductions in DNA synthesis in VSMCs, suggesting a possible relationship between cPLA 2 and proliferation (25,45), whereas the inhibition of a 14-kDa secretory PLA 2 with SB-203347 [(2-{2-[3,5-bis(trifluoromethyl)sulfonamido]-4-trifluoromethylphenoxy} benzoic acid)] and a calcium-independent PLA 2 with the haloenol lactone suicide substrate had no effect on VSMC growth (2). Whether cPLA 2 activation is involved in ANG II-induced neointimal growth or VSMC proliferation after vascular injury is not known.…”