Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.2.30 (PARP)
 13,611 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of endogenous ADP-ribosylation in mediating the activation of the Ca(2+)-activated K(+) channels was determined in bovine coronary arteries. Endogenous ADP-ribosylation was examined by incubating coronary arterial homogenates or lysates of cultured coronary arterial smooth muscle cells with [adenylate-(32)P]NAD. Four (32)P-labeled proteins were observed at 51, 52, 80, and 124 kDa in the homogenates and lysates. This reaction was enhanced by the addition of 11,12-epoxyeicosatrienoic acid (11,12-EET), a cytochrome P450-derived eicosanoid, and GTP to the incubation. By Western blot analysis, 42- and 70-kDa proteins were recognized by specific antibodies against ADP-ribosyltransferase in the coronary arterial homogenates and smooth muscle cell lysate but not in the lysate of endothelial cells. The 52-kDa acceptor protein of endogenous ADP-ribosylation comigrated with a protein ADP-ribosylated by cholera toxin and was recognized and immunoprecipitated by an anti-G(S)alpha antibody. These results suggest that G(S)alpha is one of several acceptors of the ADP-ribose moiety. As shown by the patch-clamp technique, 11,12-EET stimulated the activation of the K(+) channels in the smooth muscle cells, and this activation was completely blocked by novobiocin, vitamin K(1), 3-aminobenzamide, and m-iodobenzylguanidine, inhibitors of endogenous mono-ADP-ribosyltransferases. We conclude that endogenous mono-ADP-ribosyltransferases are present in smooth muscle from bovine coronary arteries. These enzymes transfer ADP-ribose to the cellular proteins such as G(S)alpha and may mediate intracellular signal transduction in coronary vascular smooth muscle. In the coronary circulation, the ADP-ribosylation signaling pathway may play an important role in mediating the activation of the K(+) channels induced by 11,12-EET.
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PMID:11,12-Epoxyeicosatrienoic acid stimulates endogenous mono-ADP-ribosylation in bovine coronary arterial smooth muscle. 1045 63

Epoxyeicosatrienoic acids (EETs) are arachidonic acid metabolites of cytochrome P450 monooxygenase, which are released from endothelial cells and dilate arteries. Dilation seems to be caused by activation of large-conductance Ca2+ activated K+ channels (BK(Ca)) leading to membrane hyperpolarization. Previous studies suggest that EETs activate BK(Ca) channels via ADP-ribosylation of the G protein Galphas with a subsequent membrane-delimited action on the channel [Circ Res 78:415-423, 1996; 80:877-884, 1997; 85:349-356, 1999]. The present study examined whether this pathway is present in human embryonic kidney (HEK) 293 cells when the BK(Ca) alpha-subunit (cslo-alpha) is expressed without the beta-subunit. 11,12-EET increased outward K+ current in whole-cell recordings of HEK293 cells. In cell-attached patches, 11,12-EET also increased the activity of cslo-alpha channels without affecting unitary conductance. This action was mimicked by cholera toxin. The ADP-ribosyltransferase inhibitors 3-aminobenzamide and m-iodobenxylguanidine blocked the stimulatory effect of 11,12-EET. In inside-out patches 11,12-EET was without effect on channel activity unless GTP was included in the bathing solution. GTP and GTPgammaS alone also activated cslo-alpha channels. Dialysis of cells with anti-Galphas antibody completely blocked the activation of cslo-alpha channels by 11,12-EET, whereas anti-Galphai/o and anti-Gbetagamma antibodies were without effect. The protein kinase A inhibitor KT5720 and the adenylate cyclase inhibitor SQ22536 did not reduce the stimulatory effect of 11,12-EET on cslo-alpha channels in cell-attached patches. These data suggest that EET leads to Galphas-dependent activation of the cslo-alpha subunits expressed in HEK293 cells and that the cslo-beta subunit is not required.
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PMID:Regulation of BK(Ca) channels expressed in human embryonic kidney 293 cells by epoxyeicosatrienoic acid. 1112 19

Recently, we reported that 11,12-epoxyeicosatrienoic acid (11,12-EET) potently activates rat mesenteric arterial ATP-sensitive K(+) (K(ATP)) channels and produces significant vasodilation through protein kinase A-dependent mechanisms. In this study, we tried to further delineate the signaling steps involved in the activation of vascular K(ATP) channels by EETs. Whole cell patch-clamp recordings [0.1 mM ATP in the pipette, holding potential (HP) = 0 mV and testing potential (TP) = -100 mV] in freshly isolated rat mesenteric smooth muscle cells showed small glibenclamide-sensitive K(ATP) currents (19.0 +/- 7.9 pA, n = 5) that increased 6.9-fold on exposure to 5 microM 14,15-EET (132.0 +/- 29.0 pA, n = 7, P < 0.05 vs. control). With 1 mM ATP in the pipette solution, K(ATP) currents (HP = 0 mV and TP = -100 mV) were increased 3.5-fold on exposure to 1 microM 14,15-EET (57.5 +/- 14.3 pA, n = 9, P < 0.05 vs. baseline). In the presence of 100 nM iberiotoxin, 1 microM 14,15-EET hyperpolarized the membrane potential from -20.5 +/- 0.9 mV at baseline to -27.1 +/- 3.0 mV (n = 6 for both, P < 0.05 vs. baseline), and the EET effects were significantly reversed by 10 microM glibenclamide (-21.8 +/- 1.4 mV, n = 6, P < 0.05 vs. EET). Incubation with 5 microM 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE), a 14,15-EET antagonist, abolished the 14,15-EET effects (31.0 +/- 11.8 pA, n = 5, P < 0.05 vs. 14,15-EET, P = not significant vs. control). The 14,15-EET effects were inhibited by inclusion of anti-G(s)alpha antibody (1:500 dilution) but not by control IgG in the pipette solution. The effects of 14,15-EET were mimicked by cholera toxin (100 ng/ml), an exogenous ADP-ribosyltransferase. Treatment with the ADP-ribosyltransferase inhibitors 3-aminobenzamide (1 mM) or m-iodobenzylguanidine (100 microM) abrogated the effects of 14,15-EET on K(ATP) currents. These results were corroborated by vasodilation studies. 14,15-EET dose-dependently dilated isolated small mesenteric arteries, and this was significantly attenuated by treatment with 14,15-EEZE or 3-aminobenzamide. These results suggest that 14,15-EET activates vascular K(ATP) channels through ADP-ribosylation of G(s)alpha.
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PMID:Mechanism of rat mesenteric arterial KATP channel activation by 14,15-epoxyeicosatrienoic acid. 1653 88