Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endothelin, a potent vasoactive peptide originally isolated from cultured porcine endothelial cells, (1) elicits hemodynamic and glycogenolytic actions in perfused rat liver; (2) evokes phosphoinositide signaling in hepatic cells; and (3) stimulates synthesis of mediators in Kupffer cells and glucose production in hepatocytes. Recently, we characterized receptor(s) for endothelin on hepatocytes (C. R. Gandhi, R. H. Behal, S. A. K. Harvey, T. Nouchi, and M. S. Olson, Biochem. J. 287, 897-904, 1992). Both hepatocytes and Kupffer cells rapidly internalize [125I]endothelin-1 ([125I]ET-1). In the present study we exposed primary cultures of hepatocytes or Kupffer cells to [125I]ET-1 and analyzed the radiolabeled metabolites which appeared in the cell medium. Six metabolites were separated by high-performance liquid chromatography (HPLC) from hepatocyte medium; these peaks had approximate elution times of 5 (free iodide), 22, 35, 37, 38, and 41 min, respectively, whereas the elution time for [125I]ET-1 was 43 min. The kinetics of formation of the metabolites, and experiments using excess unlabeled ET-1, both showed that internalization of the native peptide by hepatocytes is required for the metabolism of [125I]ET-1 into metabolite, and for the subsequent deiodination of metabolite. The formation of metabolites does not require internalization of the native peptide. In Kupffer cells, the cell medium contained only metabolite and metabolite. Internalization of the native peptide was required for the formation of metabolite but not for metabolite. Three classes of [125I]ET-1 metabolites from hepatic cells also were separated by sequential precipitation with trichloroacetic acid (TCA) and with silver nitrate. This procedure facilitated multiple rapid assays of [125I]ET-1 metabolism. Phosphoramidon, an inhibitor of neutral metalloendopeptidases, did not affect significantly the binding or the metabolism of [125I]ET-1 by hepatocytes or Kupffer cells. The aminopeptidase inhibitor bacitracin strongly attenuated [125I]ET-1 metabolism by hepatocytes, with a concomitant increase in the intracellular content of [125I]ET-1. These data suggest that enzymes capable of endothelin degradation are present both on the surface and in the intracellular compartment of hepatic cells, and that endothelin is not metabolized by neutral endopeptidase 24.11 in the liver.
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PMID:Hepatic effects of endothelin: metabolism of [125I]endothelin-1 by liver-derived cells. 834 54

The pharmacologic properties of CGS 26393, a prodrug of the endothelin-converting enzyme/neutral endopeptidase 24.11 inhibitor CGS 26303, were examined in conscious Sprague-Dawley rats. After oral administration of CGS 26393 at 30 mg/kg, the free concentrations of CGS 26303 in plasma were calculated to be 1.7 +/- 0.3, 1.2 +/- 0.2, and 0.31 +/- 0.05 microM at 4, 8, and 24 h, respectively. CGS 26393 inhibited the pressor response produced by exogenous big ET-1 in a dose-dependent manner. A 70% inhibition of the pressor response was observed when the prodrug was administered at 30 mg/kg p.o. As predicted by its pharmacokinetics, the inhibitory activity of CGS 26393 persisted for up to 8 h. These findings demonstrate that CGS 26393 in an orally active, long-acting ECE inhibitor in vivo.
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PMID:Inhibition of big ET-1-induced pressor response by an orally active dual inhibitor of endothelin-converting enzyme and neutral endopeptidase 24.11. 858 71

To develop a new family of endothelin-converting enzyme (ECE) inhibitors, we assessed the inhibitory properties of an N- and C-terminal-truncated analogue of big endothelin (ET)-1[1-38], [Phe22]-big-ET-1 [19-37], on the renal vasoconstrictor properties of big ET-1 and ET-1. We had previously shown that a 60-min infusion of phosphoramidon (100 microM) potently inhibits big-ET-1 but not ET-1-induced vasoconstriction in the rabbit perfused kidney. A 1-min preinfusion of the analogue (100 microM) was sufficient to markedly blunt the vasoconstrictor actions of big ET-1 (250 pmol) (control 19.3 +/- 1.0 mm Hg; in presence of [Phe22]-big ET-1[19-37] 4.8 +/- 1.6 mm Hg; n = 6, p < 0.001). A 10- and 60-min preinfusion of the substrate analogue at concentrations of 50 and 5 microM, respectively, reduced the response of big ET-1 to 9.3 +/- 2.3 mm Hg and 3.6 +/- 1.8 mm Hg (n = 3, p < 0.01 compared to control). [Phe22]-big ET-1[19-37] was inactive against ET-1-induced vasoconstriction (10 pmol) and was devoided of intrinsic vasoactivity. All experiments were performed on kidneys pretreated with SQ-28603 (1 microM), a neutral endopeptidase inhibitor. Our results suggest that [Phe22]-big ET-1[19-37] may be a useful lead molecule for the development of more selective and enzyme-resistant inhibitors of the membrane-bound ECE.
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PMID:[Phe22]-big endothelin-1[19-37]: a new and potent inhibitor of the endothelin-converting enzyme. 858 72

We have characterized the endothelin-converting enzyme (ECE)-like activity involved in big endothelin (ET)-1-induced contraction in rabbit saphenous artery (RSA). Big ET-1 30 nM caused a contraction that was independent of the vascular endothelium. Phosphoramidon and the neutral endopeptidase (NEP) inhibitors thiorphan and candoxatrilat blocked the vasoconstriction caused by big ET-1 in endothelium-denuded RSA. Candoxatrilat (IC50 17 nM) and thiorphan (IC50 2.5 nM), were 5- to 30-fold more potent than phosphoramidon (IC50 83 nM). Other protease inhibitors were inactive. In cultured endothelial cells the ET-1 release was inhibited only by phosphoramidon (IC50 16 microM) but at a concentration 200-fold that required an endothelium-denuded RSA. In conclusion, we can speculate that the big ET-1 contraction in RSA is mediated by an ECE, probably present on smooth muscle cells, which is susceptible to NEP inhibitors and is different from the ECE on endothelial cells.
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PMID:Characterization of big endothelin-1-induced contraction in rabbit saphenous artery. 858 74

We have developed a method to harvest and culture Clara cells isolated from guinea pig lungs. Their identity was confirmed by the presence of CC16kD protein specific for these cells; we studied their capacity to generate endothelin 1 (ET-1). Using monoclonal antibody and immunofluorescence techniques, ET-1 was localized in these cultured Clara cells. The basal release of immunoreactive endothelin (ir-ET), measured by radioimmunoassay, from cultured Clara cells incubated for 2, 6, and 10 h was 74.8 +/- 11.1, 230.0 +/- 32.0 and 331.0 +/- 22.9 pg/ml, respectively. Treatment of Clara cells with phosphoramidon (100 microM), an inhibitor of the endothelin-converting enzyme, caused a significant reduction of the ir-ET release by 40% after a 6-h incubation period (P<0.01). Following treatment with 1 mM phosphoramidon, ir-ET was decreased by 73% and 76% after 6- and 10-h incubation periods, respectively (P<0.01). In contrast, treatment with thiorphan (1 mM), an inhibitor of neutral endopeptidase, increased the levels of ir-ET in the cell supernatant. High-performance liquid chromatography of supernatants from cultured Clara cells revealed one peak corresponding to the retention time of synthetic ET-1. This peak was greatly reduced following treatment of the cells with phosphoramidon (1 mM) but not with thiorphan (1 mM). Our results suggest that Clara cells release ET-1, a potent bronchoconstrictive agent. Furthermore, the synthesis of ET-1 is dependent on a phosphoramidon-sensitive endothelin-converting enzyme. Secretion of this peptide by Clara cells may play a role, directly or indirectly, in lung pathophysiology.
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PMID:Guinea pig Clara cells secrete endothelin 1 through a phosphoramidon-sensitive pathway. 860 Sep 40

Endothelin-converting enzyme-1 (ECE-1) is involved in the conversion of big endothelins (big ETs) into endothelins (ETs) and shows sequence similarity with neutral endopeptidase-24.11 (NEP). Unlike NEP, ECE-1 exists as a disulphide-linked dimer. Here we reveal that Cys412 is solely responsible for the dimerization of rat ECE-1. The C412S mutant enzyme, which existed as a monomer, showed no difference in glycosylation level, subcellular localization of clustering structure formation, but showed a higher K(m) and lower kcat for big ET-1 compared with the wild-type enzyme. These results indicate that dimerization of ECE-1 is preferential for effective conversion of big ETs into ETs. In addition, complete loss of activity in the mutants E592Q, E651Q and H716Q confirmed that these residues are responsible for catalytic activity, zinc binding and stabilization of the intermediate during the transition state respectively. In contrast, the catalytic properties of mutant enzymes containing a substitution at Arg129 or Glu752 were not markedly different from those of the wild-type enzyme, suggesting that these residues play only a minor role, if any, in substrate binding, in contrast with their role in NEP.
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PMID:Rat endothelin-converting enzyme-1 forms a dimer through Cys412 with a similar catalytic mechanism and a distinct substrate binding mechanism compared with neutral endopeptidase-24.11. 864 69

Endothelin converting enzyme (ECE) from intact cells of a permanent human endothelial cell line, EA.hy926, was studied by examining the effects of phosphoramidon, an endothelin converting enzyme inhibitor, on the levels of secreted endothelin-1 and big endothelin-1. The specific ECE activity was demonstrated by a phosphoramidon dose-dependent decrease in ET-1 level with a concomitant increase in big ET-1 level. By using a specific neutral endopeptidase 24.11 (NEP 24.11) inhibitor, thiorphan, it was also shown that the phosphoramidon-sensitive ET-1 degrading activity in this cell line is due to the NEP 24.11 activity. Other serine, acid, and cysteine protease inhibitors had no effect on the endogenous synthesis of ET-1 and big ET-1 supporting the evidence that ECE is insensitive to these protease inhibitors as has been demonstrated with the isolated enzyme.
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PMID:Characterization of endothelin converting enzyme from intact cells of a permanent human endothelial cell line, EA.hy926. 882 9

The intratracheal (i.t.) instillation of Sephadex beads into rat induced inflammation and a 30-fold increase in the endothelin-1-like immunoreactivity (ET-1-LI) of broncho-alveolar lavage fluid. The levels were highest 24 h after the instillation and had declined significantly after 48 h. At a dose of 1 mg kg-1 i.t., the glucocorticosteroid budesonide almost abolished this response. Phosphoramidon, which inhibits neutral endopeptidase, an enzyme reported to degrade ET-1 and also to inhibit the endothelin-converting enzyme, potentiated the Sephadex-induced rise in ET-1-LI. Chymostatin and heparin, which are reported to reduce the formation of ET-1, did not affect the increase in ET-1-LI. The present model represents a very reactive system for analyzing the changes in ET-1 levels during inflammation.
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PMID:Release of endothelin-1 into rat airways following Sephadex-induced inflammation; modulation by enzyme inhibitors and budesonide. 896 64

The formation of endothelins (ET) from exogenous big-ET-1, -2 and -3 was investigated in cultured guinea pig Clara cells. When Clara cells were incubated with 10(-9) or 10(-8) M human big-ET-1 (1-38), the release of ET was 69.9 +/- 7.6 and 221.6 +/- 25 fmol/ml respectively, after 1 h incubation period. Treatment of Clara cells with 1 mM phosphoramidon strongly suppressed (80%) the conversion of big-ET-1 to ET-1 during 1, 2 and 6 h incubation periods. Treatment of Clara cells with thiorphan (1 mM), an inhibitor of neutral endopeptidase, decreased by 44 and 26% the levels of immunoreactive endothelin (ir-ET) in the cell supernatant respectively, after 1 and 2 h incubation periods. When Clara cells were incubated with 10(-8) M human big-ET-2 (1-38), the release of ir-ET was 287.6 +/- 8.9 fmol/ml after a 1 h incubation period. Phosphoramidon and thiorphan (1 mM) reduced the amount of ir-ET generated from exogenous human big-ET-2 (10(-8) M) by 69 and 56%, respectively. When Clara cells were incubated with 10(-8) M human big-ET-3 (1-41), the release of ET was not increased after a 1 h incubation period. Our results suggest that guinea pig Clara cells convert exogenous big-ET-1 and -2 but not big-ET-3 into ET-1 and ET-2, respectively, through metalloproteinases sensitive to both phosphoramidon and thiorphan.
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PMID:Phosphoramidon and thiorphan suppress the generation of endothelin (ET) from exogenous big-endothelin by guinea pig Clara cells. 911 Mar 81

Mammalian cell-surface peptidases participate in the postsecretory processing and metabolism of neuropeptides and peptide hormones. Neutral endopeptidase-24.11 (NEP) is the prototype of a family of zinc metallopeptidases that also includes the endothelin-converting enzymes (ECE) and which are structurally related to the bacterial enzymes thermolysin and lactococcal endopeptidase. Two other mammalian gene products exhibit strong homology with NEP: the erythrocyte cell-surface antigen, KELL; and the putative product of the PEX gene, which has been associated with X-linked hypophosphatemic rickets. No enzymic activity has yet been attributed to KELL and PEX proteins, and they remain peptidases in search of a substrate. A wide range of biologically active peptide substrates has been described for NEP, of which the enkephalins and the atrial natriuretic peptide family have assumed greatest significance. Endothelin-converting enzyme catalyses the final step in the biosynthesis of the vasoconstrictor peptide, endothelin (ET). Like NEP, it is a type II integral membrane protein, but is expressed predominantly in endothelial cells. Isoforms of ECE (ECE-1alpha, ECE-1beta, and ECE-2) exist that differ in a number of characteristics. In particular, ECE-1, through the paracrine effects of ET-1, may contribute to the proliferation of smooth muscle after angioplasty and to the development of human atherosclerosis. Inhibitors of ECE and NEP may have important therapeutic applications in cardiovascular and renal medicine.
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PMID:Mammalian membrane metallopeptidases: NEP, ECE, KELL, and PEX. 914 2


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