17-ODYA

17-ODYA is a potent inhibitor of cytochrome P450 fatty acid ω-hydroxylase [1].

ω-hydroxylase is a member of the cytochrome P450 superfamily of enzymes, which are monooxygenases that involved in synthesis of steroids, cholesterol and other lipids. ω-hydroxylase inactivates and degrades leukotriene B4, a potent mediator of inflammation.

In isolated single cells derived from rat portal vein, 17-ODYA (5 μM) inhibited delayed rectifier current (IK(V)) but didn’t influence A-type current (IK(A)). Also, 17-ODYA (5 μM) increased current flow through Ca-sensitive K-channel (BKCa) [2].

In renal cortical microsomes of rats, 17-ODYA inhibited the formation of epoxyeicosatrienoic acids, 20-hydroxyeicosatetraenoic acid and dihydroxyeicosatrienoic acids with IC50 value < 100 nM. 17-ODYA inhibited the omega-hydroxylation of arachidonic acid by 61.3% and increased sodium excretion and urine flow [1]. In rabbit arteries with both endothelium-intact (E+) and endothelium-removal (E-), 17-ODYA increased the efficacy to angiotensin II. Also, 17-ODYA inhibited Ach-relaxation. 17-ODYA improved vasoconstrictor cyclooxygenase-2 metabolites release by inhibition of prostaglandin-ω-hydroxylase [3].

References:
[1].  Zou AP, Ma YH, Sui ZH, et al. Effects of 17-octadecynoic acid, a suicide-substrate inhibitor of cytochrome P450 fatty acid omega-hydroxylase, on renal function in rats. J Pharmacol Exp Ther, 1994, 268(1): 474-481.
[2].  Edwards G, Zygmunt PM, Högestätt ED, et al. Effects of cytochrome P450 inhibitors on potassium currents and mechanical activity in rat portal vein. Br J Pharmacol, 1996, 119(4): 691-701.
[3].  Jerez S, Sierra L, de Bruno MP. 17-Octadecynoic acid improves contractile response to angiotensin II by releasing vasocontrictor prostaglandins. Prostaglandins Other Lipid Mediat, 2012, 97(1-2): 36-42.

Quantitative Imaging of Lipid Synthesis and Lipolysis Dynamics in Caenorhabditis elegans by Stimulated Raman Scattering Microscopy.[Pubmed:30589537]

Anal Chem. 2019 Feb 5;91(3):2279-2287.

Quantitative methods to precisely measure cellular states in vivo have become increasingly important and desirable in modern biology. Recently, stimulated Raman scattering (SRS) microscopy has emerged as a powerful tool to visualize small biological molecules tagged with alkyne (C identical withC) or carbon-deuterium (C-D) bonds in the cell-silent region. In this study, we developed a technique based on SRS microscopy of vibrational tags for quantitative imaging of lipid synthesis and lipolysis in live animals. The technique aims to overcome the major limitations of conventional fluorescent staining and lipid extraction methods that do not provide the capability of in vivo quantitative analysis. Specifically, we used three bioorthogonal lipid molecules (the alkyne-tagged fatty acid 17-ODYA, deuterium-labeled saturated fatty acid PA-D31, and unsaturated fatty acid OA-D34) to investigate the metabolic dynamics of lipid droplets (LDs) in live Caenorhabditis elegans ( C. elegans). Using a hyperspectral SRS (hsSRS) microscope and subtraction method, the interfering non-Raman background was eliminated to improve the accuracy of lipid quantification. A linear relationship between SRS signals and fatty acid molar concentrations was accurately established. With this quantitative analysis tool, we imaged and determined the changes in concentration of the three fatty acids in LDs of fed or starved adult C. elegans. Using the hsSRS imaging mode, we also observed the desaturation of fatty acids in adult C. elegans via spectral analysis on the SRS signals from LDs. The results demonstrated the unique capability of hsSRS microscopy in quantitative analysis of lipid metabolism in vivo.

Palmitoylation controls trafficking of the intracellular Ca(2+) channel MCOLN3/TRPML3 to regulate autophagy.[Pubmed:30215288]

Autophagy. 2018 Sep 14:1-14.

MCOLN3/TRPML3 is a Ca(2+)-permeable cation channel that is expressed in multiple subcellular compartments with dynamic localization. Our previous studies suggest that upon macroautophagy/autophagy induction MCOLN3/TRPML3 is recruited and provides Ca(2+) for the fusion process in autophagosome biogenesis. However, how intracellular trafficking and the Ca(2+) channel function of MCOLN3/TRPML3 are related to autophagy are not known. Here we report that MCOLN3/TRPML3 undergoes palmitoylation at its C-terminal region, which is required for dynamic trafficking and cellular function of MCOLN3/TRPML3 in autophagy. Palmitoylation regulated MCOLN3/TRPML3 surface expression and trafficking, but not channel properties or localization and function of intracellular MCOLN3/TRPML3. Activation of intracellular MCOLN3/TRPML3 induced robust Ca(2+) release, which solely increased autophagy in Ca(2+)- and palmitoylation-dependent manners. Palmitoylation regulated not only intracellular MCOLN3/TRPML3 trafficking to autophagic structures but also autophagic flux in induced autophagy. Importantly, nutrient starvation activated MCOLN3/TRPML3 to release Ca(2+) and increased the level of MCOLN3/TRPML3 palmitoylation. Disruption of MCOLN3/TRPML3 palmitoylation, however, abolished the starvation-induced MCOLN3/TRPML3 activation without affecting channel activity. These results suggest that trafficking and channel function of MCOLN3/TRPML3 are regulated in the context of autophagy, and palmitoylation is a prerequisite for the function of MCOLN3/TRPML3 as a Ca(2+) channel in autophagosome formation by controlling its trafficking between subcellular compartments. ABBREVIATIONS: 17-ODYA, 17-octadecynoic acid; 2-BP, 2-bromopalmitate; BFA, brefeldin A; DN, dominant-negative; GPN, glycyl-L-phenylalanine-beta-naphthylamide; HN, hydroxylamine; KD, knockdown; MCOLN3/TRPML3, mucolipin 3; MS, mass spectrometry; PAT, palmitoyl acyltransferase; PM, plasma membrane; WT, wild type; ZDHHC, a zinc-finger motif and an Asp-His-His-Cys sequence.

beta-adrenergic Receptor-stimulated Cardiac Myocyte Apoptosis: Role of Cytochrome P450 omega-hydroxylase.[Pubmed:28768289]

J Cardiovasc Pharmacol. 2017 Aug;70(2):94-101.

Prolonged or excessive beta-adrenergic activation leads to cardiac myocyte loss and heart dysfunction; however, the underlying cellular mechanisms are still unclear. Therefore, we first confirmed the effect of isoproterenol (ISO), a beta-adrenergic receptor agonist, on cardiac toxicity using TUNEL and caspase activity assays in cultured rat cardiomyocytes. ISO treatment significantly increased cardiomyocyte apoptosis. Persistent ISO stimulation of cardiomyocytes also increased the expression of CYP4A3, a major CYP450 omega-hydroxylase that produces 20-hydroxyeicosatetraenoic acid (20-HETE) in a time-dependent manner. Next, we examined the effect of ISO and 20-HETE on cardiomyocyte apoptosis using annexin V and propidium iodide staining. Treatment with either 20-HETE or ISO significantly increased cardiomyocyte apoptosis, and inhibition of 20-HETE production using 17-ODYA, a CYP450 omega-hydroxylase inhibitor, dramatically attenuated ISO-induced cardiomyocyte apoptosis. To determine the apoptotic pathway involved, the mitochondrial membrane potential (DeltaPsim) was measured by detecting the ratio of JC-1 green/red emission intensity. The results demonstrated that 17-ODYA significantly abolished ISO-induced disruption of DeltaPsim and that 20-HETE alone induced a marked disruptive effect on DeltaPsim in cardiomyocytes. In addition, 20-HETE-induced disruption of DeltaPsim and apoptosis was significantly attenuated by KN93, a CaMKII inhibitor. Taken together, these results demonstrate that 20-HETE treatment induces significant apoptosis via mitochondrial-dependent pathways, and that inhibition of 20-HETE production using 17-ODYA attenuates ISO-induced cardiomyocyte apoptosis.

Involvement of the arachidonic acid cytochrome P450 epoxygenase pathway in the proliferation and invasion of human multiple myeloma cells.[Pubmed:27077015]

PeerJ. 2016 Apr 11;4:e1925.

Cytochrome P450 (CYP) epoxygenases and the metabolites epoxyeicosatrienoic acids (EETs) exert multiple biological effects in various malignancies. We have previously found EETs to be secreted by multiple myeloma (MM) cells and to be involved in MM angiogenesis, but the role of the arachidonic acid cytochrome P450 epoxygenase pathway in the proliferation and mobility of MM cells remains unknown. In the present study, we found that MM cell lines generated detectable levels of 11,12-EET/14,15-EET and that increased levels of EETs were found in the serum of MM patients compared to healthy donors. The addition of exogenous EETs induced significantly enhanced proliferation of MM cells, whereas 17-octadecynoic acid (17-ODYA), an inhibitor of the CYP epoxygenase pathway, inhibited the viability and proliferation of MM cells. Moreover, this inhibitory effect could be successfully reversed by exogenous EETs. 17-ODYA also inhibited the motility of MM cells in a time-dependent manner, with a reduction of the gelatinolytic activity and protein expression of the matrix metalloproteinases (MMP)-2 and MMP-9. These results suggest the CYP epoxygenase pathway to be involved in the proliferation and invasion of MM cells, for which 17-ODYA could be a promising therapeutic drug.

[Effect of electroacupuncture intervention on neurological function, cerebral blood flow and cerebral cytochrome P 450 2 C 11 mRNA expression in rats with focal cerebral ischemia].[Pubmed:25518105]

Zhen Ci Yan Jiu. 2014 Oct;39(5):345-50.

OBJECTIVE: To observe the effect of electroacupuncture(EA) intervention on changes of neurological function and expression of cerebral cytochrome P 450 2 C 11 (CYP 2 0 11) mRNA in focal cerebral ischemia (FCI) rats, so as to explore its mechanism underlying improvement of ischemic cerebral vascular disease. METHODS: Wistar rats were randomly divided into normal, model, EA and EA+ 17-ODYA (17-Octadecynoic acid, an inhibitor for the metabolism of arachidonic acid by cytochrome P 450) groups. Focal cerebral ischemia rats were induced by middle cerebral artery occlusion (MCAO) with thread embolus. EA was applied to bilateral "Neiguan"(PC 6 ) and "Quchi" (LI 11) after MCAO. Zea Longa's score and beam walking test (BWT) score of rats were used to evaluate the neurological impairment. Local cerebral blood flow (LCBF) of the pial tissue was moni- tored using Laser-Doppler Flowmetry. The expression of cerebral CYP 2 C 11 mRNA was examined by Real-time Quantitative PCR (qPCR). RESULTS: In comparison with the normal group, BWT score and LCBF of the model group were significantly decreased (P<0.05), and Zea Longa's score and cerebral CYP 2 C 11 mRNA expression level of the model group were significantly increased (P<0.05). While in comparison with the model group, BWT score, LCBF and cerebral CYP2 C 11 mRNA levels were considerably up-regulated and Zea Longa's score was down-regulated in the EA group (P<0.05) rather than in the EA + 17- ODYA group (P<0.05). H.E. stainshowed that the nerve impairment of the ischemic cerebral tissue including the neuronal degeneration, necrosis, apoptosis, etc. was relatively milder in the EA group. CONCLUSION: EA intervention can improve cerebral blood flow and up-regulate cerebral CYP 2 C 11 mRNA expression in FCI rats, which may contribute to its action in improving neu- rological impairment.

20-Hydroxyeicosatetraenoic acid contributes to the inhibition of K+ channel activity and vasoconstrictor response to angiotensin II in rat renal microvessels.[Pubmed:24324797]

PLoS One. 2013 Dec 4;8(12):e82482.

The present study examined whether 20-hydroxyeicosatetraenoic acid (HETE) contributes to the vasoconstrictor effect of angiotensin II (ANG II) in renal microvessels by preventing activation of the large conductance Ca(2+)-activated K(+) channel (KCa) in vascular smooth muscle (VSM) cells. ANG II increased the production of 20-HETE in rat renal microvessels. This response was attenuated by the 20-HETE synthesis inhibitors, 17-ODYA and HET0016, a phospholipase A2 inhibitor AACOF3, and the AT1 receptor blocker, Losartan, but not by the AT2 receptor blocker, PD123319. ANG II (10(-11) to 10(-6) M) dose-dependently decreased the diameter of renal microvessels by 41 +/- 5%. This effect was blocked by 17-ODYA. ANG II (10(-7) M) did not alter KCa channel activity recorded from cell-attached patches on renal VSM cells under control conditions. However, it did reduce the NPo of the KCa channel by 93.4 +/- 3.1% after the channels were activated by increasing intracellular calcium levels with ionomycin. The inhibitory effect of ANG II on KCa channel activity in the presence of ionomycin was attenuated by 17-ODYA, AACOF3, and the phospholipase C (PLC) inhibitor U-73122. ANG II induced a peak followed by a steady-state increase in intracellular calcium concentration in renal VSM cells. 17-ODYA (10(-5) M) had no effect on the peak response, but it blocked the steady-state increase. These results indicate that ANG II stimulates the formation of 20-HETE in rat renal microvessels via the AT1 receptor activation and that 20-HETE contributes to the vasoconstrictor response to ANG II by blocking activation of KCa channel and facilitating calcium entry.

Role of S-palmitoylation on IFITM5 for the interaction with FKBP11 in osteoblast cells.[Pubmed:24058703]

PLoS One. 2013 Sep 18;8(9):e75831.

Recently, one of the interferon-induced transmembrane (IFITM) family proteins, IFITM3, has become an important target for the activity against influenza A (H1N1) virus infection. In this protein, a post-translational modification by fatty acids covalently attached to cysteine, termed S-palmitoylation, plays a crucial role for the antiviral activity. IFITM3 possesses three cysteine residues for the S-palmitoylation in the first transmembrane (TM1) domain and in the cytoplasmic (CP) loop. Because these cysteines are well conserved in the mammalian IFITM family proteins, the S-palmitoylation on these cysteines is significant for their functions. IFITM5 is another IFITM family protein and interacts with the FK506-binding protein 11 (FKBP11) to form a higher-order complex in osteoblast cells, which induces the expression of immunologically relevant genes. In this study, we investigated the role played by S-palmitoylation of IFITM5 in its interaction with FKBP11 in the cells, because this interaction is a key process for the gene expression. Our investigations using an established reporter, 17-octadecynoic acid (17-ODYA), and an inhibitor for the S-palmitoylation, 2-bromopalmitic acid (2BP), revealed that IFITM5 was S-palmitoylated in addition to IFITM3. Specifically, we found that cysteine residues in the TM1 domain and in the CP loop were S-palmitoylated in IFITM5. Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11. These results indicate that the S-palmitoylation on IFITM5 promotes the interaction with FKBP11. Finally, we investigated bone nodule formation in osteoblast cells in the presence of 2BP, because IFITM5 was originally identified as a bone formation factor. The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation.

The palmitoylation state of PMP22 modulates epithelial cell morphology and migration.[Pubmed:23127255]

ASN Neuro. 2012 Dec 3;4(6):409-21.

PMP22 (peripheral myelin protein 22), also known as GAS 3 (growth-arrest-specific protein 3), is a disease-linked tetraspan glycoprotein of peripheral nerve myelin and constituent of intercellular junctions in epithelia. To date, our knowledge of the post-translational modification of PMP22 is limited. Using the CSS-Palm 2.0 software we predicted that C85 (cysteine 85), a highly conserved amino acid located between the second and third transmembrane domains, is a potential site for palmitoylation. To test this, we mutated C85S (C85 to serine) and established stable cells lines expressing the WT (wild-type) or the C85S-PMP22. In Schwann and MDCK (Madin-Darby canine kidney) cells mutating C85 blocked the palmitoylation of PMP22, which we monitored using 17-ODYA (17-octadecynoic acid). While palmitoylation was not necessary for processing the newly synthesized PMP22 through the secretory pathway, overexpression of C85S-PMP22 led to pronounced cell spreading and uneven monolayer thinning. To further investigate the functional significance of palmitoylated PMP22, we evaluated MDCK cell migration in a wound-healing assay. While WT-PMP22 expressing cells were resistant to migration, C85S cells displayed lamellipodial protrusions and migrated at a similar rate to vector control. These findings indicate that palmitoylation of PMP22 at C85 is critical for the role of the protein in modulating epithelial cell shape and motility.

Arachidonic acid inhibits Na(+)-K(+)-ATPase via cytochrome P-450, lipoxygenase and protein kinase C-dependent pathways in sheep pulmonary artery.[Pubmed:22155164]

Vascul Pharmacol. 2012 Jan-Feb;56(1-2):84-90.

The purpose of the study was to examine whether arachidonic acid inhibits vascular Na(+)-K(+)-ATPase in pulmonary vasculature and if so, what are the mechanisms involved. Functional Na(+)-K(+)-ATPase activity was studied in terms of K(+)-induced relaxation in sheep pulmonary arterial rings contracted with K(+)-free solution and 5-HT. Arachidonic acid (10-100 muM) caused concentration-dependent inhibition of KCl-induced relaxations and also increased basal arterial tone. Cytochrome P-450 inhibitor, 17-octadecynoic acid (17-ODYA) completely reversed the arachidonic acid (30 muM)-induced inhibition of KCl relaxation. Further, in the presence of HET0016, a selective blocker of 20-hydroxyeicosatetraenoic acid (20-HETE), arachidonic acid-induced inhibition of KCl relaxation was not evident. Accordingly, 20-HETE, a cytochrome P-450 metabolite of arachidonic acid, also significantly attenuated KCl-induced relaxations. Norhydihydroguaiaretic acid (NDGA), a lipoxygenase inhibitor, however, partially restored the relaxation to K(+), impaired in the presence of arachidonic acid (30 muM). On the other hand, cyclooxygenase inhibitor indomethacin failed to reverse the inhibitory effect of arachidonic acid on KCl-induced relaxation. Staurosporin, a protein kinase C inhibitor, completely reversed the inhibitory effect of arachidonic acid and 20-HETE on K(+)-induced relaxation. In conclusion, the results suggest that 20-HETE, a cytochrome P-450 metabolite of arachidonic acid has a predominant role in the inhibition of functional Na(+)-K(+)-ATPase activity in the sheep pulmonary artery, while the lipooxygenase pathway has a secondary role. It is also evident that protein kinase C is involved in the inhibition of Na(+)-K(+)-ATPase by arachidonic acid/20-HETE in sheep pulmonary artery.

Global profiling of dynamic protein palmitoylation.[Pubmed:22056678]

Nat Methods. 2011 Nov 6;9(1):84-9.

The reversible thioester linkage of palmitic acid on cysteines, known as protein S-palmitoylation, facilitates the membrane association and proper subcellular localization of proteins. Here we report the metabolic incorporation of the palmitic acid analog 17-octadecynoic acid (17-ODYA) in combination with stable-isotope labeling with amino acids in cell culture (SILAC) and pulse-chase methods to generate a global quantitative map of dynamic protein palmitoylation events in cells. We distinguished stably palmitoylated proteins from those that turn over rapidly. Treatment with a serine lipase-selective inhibitor identified a pool of dynamically palmitoylated proteins regulated by palmitoyl-protein thioesterases. This subset was enriched in oncoproteins and other proteins linked to aberrant cell growth, migration and cancer. Our method provides a straightforward way to characterize global palmitoylation dynamics in cells and confirms enzyme-mediated depalmitoylation as a critical regulatory mechanism for a specific subset of rapidly cycling palmitoylated proteins.

P-450-dependent epoxygenase pathway of arachidonic acid is involved in myeloma-induced angiogenesis of endothelial cells.[Pubmed:22038346]

J Huazhong Univ Sci Technolog Med Sci. 2011 Oct;31(5):596.

P-450-dependent epoxygenase pathway of arachidonic acid and the products of epoxyeicosatrienoic acids (EETs) have been demonstrated to be involved in angiogenesis and tumor progression. This study examined the expression of EETs and the role of the pathway in the angiogenesis of multiple myeloma (MM). MM cell lines of U266 and RPMI8226 were cultured, and the EETs levels (11, 12-EET and 14, 15-EET) in the supernatant were determined by ELISA. Human umbilical vein endothelial cells (HUVECs) were cultured and used for analysis of the angiogenesis activity of the two MM cell lines, which was examined both in vitro and in vivo by employing MTT, chemotaxis, tube formation and matrigel plug assays. 11, 12-EET and 14, 15-EET were found in the supernatant of the cultured MM cells. The levels of the two EETs in the supernatant of U266 cells were significantly higher than those in the RPMI8226 cell supernatant (P<0.05), and the levels paralleled the respective angiogenesis activity of the two different MM cell lines. 17-octadecynoic acid (17-ODYA), as a specific inhibitor of P450 enzyme, suppressed HUVECs proliferation and tube formation induced by MM cells. Furthermore, 17-ODYA decreased the EET levels in the supernatant of MM cells. These results suggest that EETs may play an important role in the angiogenesis of MM, and the inhibitor 17-ODYA suppresses this effect.

17-Octadecynoic acid improves contractile response to angiotensin II by releasing vasocontrictor prostaglandins.[Pubmed:21839852]

Prostaglandins Other Lipid Mediat. 2012 Jan;97(1-2):36-42.

The present study investigated the role of CYP-enzymes in the modulation of vasoconstrictor responses to angiotensin II in rabbit aortae. In arteries with the endothelium-intact (E+) the CYP-inhibitor, 17-octadecynoic acid (17 ODYA), increased the efficacy to angiotensin II (17-ODYA-effect) as well as simultaneous incubation with miconazole (epoxygenase-inhibitor) and CAY 10434 (omega-hydroxylase-inhibitor). The removal of endothelium (E-) caused potentiation of the 17 ODYA-effect. Therefore, endothelium-dependent and -independent mechanisms would be involved. 17-ODYA and miconazole reduced Ach-relaxation. Indomethacin blocked the 17-ODYA-effect in E+ and E- arteries but blunted the response to angiotensin II only in E+ arteries. NS 398 (cyclooxygenase-2-inhibitor) blocked the 17-ODYA-effect and reduced angiotensin II affinity as well as SQ 29548 (thromboxane-prostanoid (TP) receptor-inhibitor). In E- arteries, CAY 10434 enhanced angiotensin II response as well as 17-ODYA. SC 560 (cyclooxygenase-1-inhibitor) and NS 398 partially blocked the 17-ODYA-effect. In conclusion, 17-ODYA induced endothelial dysfunction by inhibiting CYP-epoxygenase and thus improves vasoconstrictor cyclooxygenase-2 metabolites release acting through TP receptors. The endothelium-independent mechanism of 17-ODYA-effect may involve increase of vasoconstrictor cyclooxygenase-metabolites induced by prostaglandin-omega-hydroxylase-inhibition.

Contribution of Ras farnesyl transferase, MAP kinase and cytochrome P-450 metabolites to endothelin-1 induced hypertension.[Pubmed:21619553]

Bosn J Basic Med Sci. 2011 May;11(2):84-6.

Endothelin 1 (ET-1) is vasoactive peptide that acts via ET-A receptors coupling inducing vascular smooth muscle cell proliferation and contraction. ET-1 is involved in the development and maintenance of hypertension. Aim of this study was to determine the contribution of Ras farnesyl transferase, mitogen activated protein kinase (MAP kinase) and cytochrome P not450 (CYP450) metabolites to ET-1 induced hypertension. ET-1 (5 pmol/kg per minute) was chronically infused into to the jugular vein by use of mini-osmotic pump for 9 days in male Sprague-Dawley rats. Mean arterial blood pressure (MABP) in ET-1-treated rats was 154+/-2 mm Hg (hypertensive rats) compared with 98+/-3 mm Hg in control (normotensive) rats. Infusion of Ras farnesyl transferase inhibitor FPTIII (138 ng/min), MAP kinase inhibitor PD-98059 (694 ng/min) and CYP450 inhibitor 17-ODYA (189 ng/min) significantly attenuated MABP to 115+/-2.5 mm Hg, 109+/-3 mm Hg and 118+/-1.5 mm Hg, respectively. These results suggest that CYP-450 metabolites and Ras/MAP kinase pathway contribute to the development of ET-1 induced hypertension. Further investigation has to be done to confirm whether activation of RAS/MAP kinase pathway by arachidonic acid metabolites plays an important role in the development of ET-1 induced hypertension.

Endothelin-1 induced vascular smooth muscle cell proliferation is mediated by cytochrome p-450 arachidonic acid metabolites.[Pubmed:20846129]

Bosn J Basic Med Sci. 2010 Aug;10(3):223-6.

Endothelins (ETs) are a family of three peptides (ET-1, ET-2, ET-3) that are implicated in the physiological control of vascular smooth muscle cell (VSMC) and myocardial contractility and growth. ET-1 is vasoactive peptide that acts via ET-A receptors coupling inducing vascular smooth muscle cell contraction. ET-1 is involved in the development and maintenance of hypertension. Aim of this study was to investigate whether ET-1 can induce vascular smooth muscle cell proliferation through arachidonic acid (AA) metabolites formed via cytochrome P not450 (CYP-450). VSMC proliferation was measured by [3H]thymidine incorporation in cultured cells treated by ET-1 (10 to l00 nmol/L) in presence of different inhibitors of CYP-450 (17-ODYA 5 mumol/L), lipoxygenase (LO) (baicalein 20 mumol/L) and cyclooxygenase (COX) (indomethacin 5 mumol/L). ET-1 (10 to 100 nmol/L) induced VSMC proliferation and this effect was attenuated by CYP-450 inhibitor (17-ODYA) and lipoxygenase (LO) inhibitor (baicalein) but not by cyclooxygenase (COX) inhibitor (indomethacin). CYP-450 and LO metabolites of AA, 20-hydroxyeicosatetraenoic acid (HETE) and 12-HETE increased [3H]thymidine incorporation in VSMC. Inhibitors of MAP kinase (PD-98059 50 mumol/L) and cPLA2 (MAFP 50 mumol/L) attenuated ET-1 as well as 20-HETE induced VSMC proliferation. These results suggest AA metabolites via CYP-450 mediates ET-1 induce VSMC proliferation.

Effects of cytochrome P450 inhibitors on potassium currents and mechanical activity in rat portal vein.[Pubmed:8904643]

Br J Pharmacol. 1996 Oct;119(4):691-701.

1. The effects of the cytochrome P450 inhibitors, proadifen, clotrimazole and 17-octadecynoic acid (17-ODYA) on K-currents in freshly-isolated single cells derived from rat portal vein and on mechanical activity in whole veins were studied. 2. When cells were stepped from -90 mV to a series of test potentials (from -80 to +50 mV), a delayed rectifier current (IK(V)) and an A-type current (IK(A)) could be identified. Proadifen (10 microM), clotrimazole (30 microM) and 17-ODYA (5 microM) each inhibited IK(V) but had little effect on IK(A). 3. When cells were held at -10 mV to inactivate the time-dependent K-currents, IK(V) and IK(A), levcromakalim (3 microM) induced a time-independent outward K-current (IK(ATP)) which was totally inhibited by clotrimazole (30 microM) and almost fully inhibited by proadifen (10 microM). 17-ODYA (5 microM) had no effect on IK(ATP) and exerted only a minor inhibitory action on this current at 20 microM. 4. 17-ODYA (5 microM) potentiated current flow through the large conductance, Ca-sensitive K-channel (BKCa). In contrast, proadifen (10 microM) had no effect on IBK(Ca) whereas clotrimazole (30 microM) exerted a small but significant inhibitory action. 5. Proadifen (10 microM) and clotrimazole (30 microM) each inhibited the magnitude but increased the frequency of spontaneous contractions in whole portal veins. 17-ODYA (5 microM) had no effect on spontaneous contractions but these were inhibited when the concentration of 17-ODYA was increased to 50 microM. 6. The spasmolytic effect of levcromakalim on spontaneous contractions was antagonized by proadifen (10-30 microM) in a concentration-dependent manner but 17-ODYA (up to 50 microM) was without effect. 7. These results in portal vein show that cytochrome P450 inhibitors exert profound effects on a variety of K-channel subtypes. This suggests that enzymes dependent on this cofactor may be important regulators of K-channel activity in smooth muscle. The relevance of these findings for the identification of the pathway involved in the synthesis of the endothelium-derived hyperpolarizing factor is discussed.

Leukotriene B4 omega-hydroxylase in human polymorphonuclear leukocytes. Suicidal inactivation by acetylenic fatty acids.[Pubmed:2997155]

J Biol Chem. 1985 Oct 25;260(24):13023-8.

Human polymorphonuclear leukocytes (PMN) not only generate and respond to leukotriene B4 (LTB4), but also catabolize this mediator of inflammation rapidly and specifically by omega-oxidation (probably due to the action of a cytochrome P-450 enzyme). To develop pharmacologically useful inhibitors of the LTB4 omega-hydroxylase in human PMN, we devised a general scheme for synthesizing terminal acetylenic fatty acids based on the "acetylenic zipper" reaction. We found that the LTB4 omega-hydroxylase in intact PMN and in PMN sonicates is inactivated in a concentration-dependent fashion by terminal acetylenic analogues of lauric, palmitic, and stearic acids (i.e. 11-dodecynoic, 15-hexadecynoic, and 17-octadecynoic acids). Consistent with a suicidal process, inactivation of the LTB4 omega-hydroxylase requires molecular oxygen and NADPH, is time-dependent, and follows pseudo-first-order kinetics. Inactivation of the omega-hydroxylase by acetylenic fatty acids also is dependent on the terminal acetylenic moiety and the carbon chain length. Saturated fatty acids lacking a terminal acetylenic moiety do not inactivate the omega-hydroxylase. In addition, the two long-chain (C16, C18) acetylenic fatty acids inactivate the omega-hydroxylase at much lower concentrations (less than 5.0 microM) than those required for inactivation by the short-chain (C12) terminal acetylenic fatty acid (100 microM). Potent suicidal inhibitors of the LTB4 omega-hydroxylase in human PMN will help elucidate the roles played by LTB4 and its omega-oxidation products in regulating PMN function and in mediating inflammation.