Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We discovered an enzyme in human platelets that deamidates substance P and other tachykinins. Because an amidated carboxyl terminus is important for biological activity, we purified and characterized this deamidase. The enzyme, released from human platelets by thrombin, was purified to homogeneity by ammonium sulfate precipitation, followed by chromatography on an octyl-Sepharose column and chromatofocusing on PBE 94. The purified enzyme exhibits esterase, peptidase, and deamidase activities. The peptidase activity (with furylacryloyl-Phe-Phe) is optimal at pH 5.0 while the esterase (benzoyl-tyrosine ethyl ester) and deamidase (D-Ala2-Leu5-enkephalinamide) activities are optimal at pH 7.0. With biologically important peptides, the enzyme acts both as a deamidase (substance P, neurokinin A, and eledoisin) and a carboxy-peptidase (with bradykinin, angiotensin I, substance P-free acid, oxytocin-free acid) at neutrality, although the carboxypeptidase action is faster at pH 5.5. Enkephalins, released upon deamidation of enkephalinamides, were not cleaved. Gly9-NH2 of oxytocin was released without deamidation. Peptides with a penultimate Arg residue were not hydrolyzed. Some properties of the deamidase are similar to those reported for cathepsin A. The deamidase is inhibited by diisopropylfluorophosphate, inhibitors of chymotrypsin-type enzymes, and mercury compounds while other inhibitors of catheptic enzymes, trypsin-like enzymes, and metalloproteases were ineffective. In gel filtration, the native enzyme has an Mr = 94,000 while in non-reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis the Mr = 52,000 indicating it exists as a dimer. After reduction, deamidase dissociates into two chains of Mr = 33,000 and 21,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. [3H]diisopropylfluorophosphate labeled the active site serine in the Mr = 33,000 chain. The first 25 amino acids of both chains were sequenced. They are identical with the sequences of the two chains of lysosomal "protective protein" which, in turn, has sequence similarity to the KEX1 gene product and carboxypeptidase Y of yeast. This protective protein complexes with beta-galactosidase and neuraminidase in lysosomes and is vitally important in maintaining their activity and stability. A defect in this protein is the cause of galactosialidosis, a severe genetic disorder. The ability of physiological stimuli (e.g. thrombin or collagen) to release the deamidase from platelets indicates that it may also be involved in the local metabolism of bioactive peptides.
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PMID:A peptidase in human platelets that deamidates tachykinins. Probable identity with the lysosomal "protective protein". 169 76

The contractile effects of 19 factors on isolated human arterial segments at term pregnancy were quantified, and 14 contractile agents were similarly applied to preterm (23 to 35 weeks) umbilical arteries. Responses to potassium chloride were used to normalize the data. At comparison with the term vessel, the preterm artery contracted more to angiotensin II and arachidonic acid and was more sensitive to oxytocin. Contractions were greater in term arteries to vasopressin, norepinephrine, prostaglandin D2, and prostaglandin E2 but similar in both group of arteries to bradykinin, histamine, acetylcholine, and prostaglandin F2 alpha. Neuropeptide Y, linoleic acid, uridine triphosphate, and thrombin were ineffective. Hyperoxia inconsistently induced weak, short-lived contractions. Contractions to cooling manifested marked desensitization and tachyphylaxis. Serotonin was the only agonist that displayed the pharmacodynamic features most likely to be important for closure: potency, efficacy, and long duration of action (greater than 2.5 hours). It was postulated that cellular elements surrounding umbilical vessels are primary sources of vasoactive agents that are important to closure of the fetoplacental circulation at birth.
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PMID:Pharmacodynamic study of maturation and closure of human umbilical arteries. 291 87

Endothelial cells of the arterial wall can generate vasodilator and vasoconstrictor substances. The prototype of a vasodilator substance formed primarily in the endothelium is prostacyclin, although its main target under physiological conditions are the platelets. In addition, the endothelial cells respond to a variety of neurohumoral mediators by the liberation of an unidentified substance(s) (endothelium-derived relaxing factor) with a potent inhibitory effect on vascular smooth muscle, presumably because it accelerates the production of cyclic GMP in the latter. Endothelium-derived relaxing factor is very unstable, and has an extremely short half-life. It is inactivated by plasma proteins and thus does not fulfill a hormonal role. A metabolite of arachidonic acid may be involved in the production of endothelium-derived relaxing factor. Among the neurohumoral mediators which release it are: acetylcholine (through activation of muscarinic receptors), adenosine di- and triphosphate (P2-purinergic receptors), bradykinin, histamine (H1- or H2-histaminergic receptors, depending on the species), serotonin (S1-serotonergic receptors), substance P, oxytocin, thrombin and vasopressin (V1-vasopressinergic receptors). The release of the factor can also be triggered by aggregating platelets (because they release adenine nucleotides and serotonin) and by increases in shear stress. It is likely that endothelium-dependent dilatation helps to prevent intraluminal coagulation in arteries with a normal intima. Absence, or dysfunction of the endothelium may favor the occurrence of vasospasm. Endothelium-dependent relaxations are reduced in atherosclerotic blood vessels.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[The endothelium and arterial reactivity]. 349 May 30

To determine the intrauterine defensive role of urinary trypsin inhibitor (UTI), we studied the effects of UTI in amniotic fluid, fetal membranes and myometrium. The level of UTI was 94 +/- 34 U/ml in neonatal urine (compared to adult urine 8.0 +/- 6.0 U/ml) and 88 +/- 37 U/ml in amniotic fluid. This may indicate that the main source of UTI in the amniotic fluid is the fetal urine. UTI was found to be concentrated in vernix, fetal intestine, amniotic membranes and uterine myometrium. Immunostaining of term amnion revealed a dark staining for UTI, whereas in premature deliveries UTI staining was markedly decreased. In myometrium, the concentration of UTI was found to be increased during pregnancy compared to non pregnant myometrium. Also, placentas were well stained for UTI in term pregnancy. Thus UTI has an important role in amniotic fluid, fetal membranes, placenta and uterine muscles. UTI has an inhibitory effect on several enzymes and cytokines. UTI was found to inhibit neutrophil elastase activity as well as trypsin activity. Its inhibitory activity was increased in the presence of lipid. LPS stimulated amnion cells trapped more UTI than unstimulated amnion cells. UTI in amnion cells was released after addition of 1% meconium solution. UTI was also found to inhibit the effect of IL-1, TNF and interleukin-8 on amnion. These results indicate that UTI localized in amnion is important in the protection of fetal membrane especially against bacterial infections and cytokines. It is known that endothelin (ET), prostaglandin F2 alpha (PGF2 alpha) and oxytocin can induce uterine contraction. UTI could inhibit uterine contractions stimulated by ET, PGF2 alpha and oxytocin in isometric contraction test. UTI could also inhibit cervical maturation induced by interleukin-8. Therefore UTI is essential for maintenance of pregnancy. From the isometric contraction tests, we assumed that UTI might works through regulation of calcium entry or availability in the cells. Initial increase in intracellular calcium was also inhibited by UTI pre incubation dose dependantly. We examined the change in intracellular calcium at single cell level by digital image analysis with Fura 2AM as a calcium probe. At resting level UTI incubation did not produce any significant changes in intracellular free calcium. Thrombin, LPS, interleukin-8 and ET-1, known calcium agonists could increase intracellular calcium in fibroblasts, amnion and uterine myocytes. Whereas as the same doses of those known calcium agonists could not change the intracellular free Ca2+ concentrations in UTI pre incubated fibroblasts, amnion cells and uterine smooth muscle cells.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Intrauterine defensive mechanism of amniotic fluid and fetal membranes]. 808 4

1. Endothelin (ET) and its mRNA are present in endometrium. Expression of ET varies across the menstrual cycle, reaching maximal levels in the premenstrual phase, suggesting a paracrine role in endometrial bleeding and/or repair. 2. The major cellular source of ET is the epithelium, although endothelium and decidualized stroma are additional sites of production. Epithelial ET is the ET-1 isoform and this is able to contract rat thoracic aortic rings ex vivo. 3. Endothelin-1 production by cultured endometrial epithelial cells is markedly increased by serum and, to a lesser extent, by transforming growth factor-beta and interleukin-1 alpha, but not by epidermal growth factor, oxytocin, arginine vasopressin, thrombin or angiotensin II, which stimulate ET production in other tissues. 4. Endothelin-1 has mitogenic actions on endometrial stromal cells; it stimulates the uptake of [3H]-thymidine, acting via the AP-1 cis element c-jun. 5. Neutral endopeptidase (NEP), a membrane-bound ectoenzyme that is capable of degrading ET, is localized principally in endometrial stroma and immunoreactivity is maximal in the secretory phase of the cycle. 6. A potential role for ET in regulating endometrial bleeding is suggested by studies on endometrium from two groups of women who were experiencing abnormal uterine bleeding: users of the contraceptive Norplant (Leiras Co., Turku, Finland) and subjects with documented menorrhagia. In both groups, ET-1 immunoreactivity in endometrial epithelium was markedly reduced compared with the normal menstrual cycle and did not vary cyclically, while NEP immunoreactivity, particularly in the epithelium, was increased. Thus, ET may be involved in endometrial bleeding, as a vasoconstrictor before the onset of menstruation when vasoconstriction is intense and, subsequently, when it may be required in the cessation of menstrual bleeding. Furthermore, the mitogenic actions of ET may play a role in endometrial regeneration and remodelling during the menstrual cycle, particularly following menstruation.
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PMID:Endometrial endothelin: regulator of uterine bleeding and endometrial repair. 1006 38

The effect of neurohypophysial hormones vasopressin and oxytocin as well as their synthetic analogs on platelet aggregation induced by thrombin or ADP was studied in vitro on washed rat platelets. Vasopressin and its analog DGAVP, as well as oxytocin enhanced thrombin-induced platelet aggregation, while their effect on ADP-induced aggregation was considerably lower. An oxytocin analog depotocin had a pronounced antithrombin effect indicated by a significant inhibition (by 81%) of thrombin-induced platelet aggregation and by assay for its antithrombin activity in the blood plasma.
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PMID:[Effects of neurohypophysial hormones and their synthetic analogs on platelet aggregation]. 1104 70

Platelet-activating factor (PAF), a phospholipid mediator of inflammation, is present in breast cancer tissue and correlates with microvessel density. In the present study, we investigated the biological significance of PAF synthesized within breast cancer. In vitro, we observed the production of PAF by two estrogen-dependent (MCF7 and T-47D) and an estrogen-independent (MDA-MB231) breast cancer cell lines after stimulation with vascular endothelial growth factor, basic fibroblast growth factor, hepatocyte growth factor, tumor necrosis factor, thrombin but not with estrogen, progesterone, and oxytocin. The sensitivity to agonist stimulation and the amount of PAF synthesized as cell-associated or released varied in different cell lines, being higher in MDA-MB231 cells, which are known to be highly invasive. We further demonstrate, by reverse transcriptase-polymerase chain reaction and cytofluorimetry, that all of the breast cancer cells express the PAF receptor and respond to PAF stimulation in terms of proliferation. Moreover, in MDA-MB231 cells PAF elicited cell motility. In vivo, two structurally different PAF receptor antagonists WEB 2170 and CV 3988 significantly reduced the formation of new vessels in a tumor induced by subcutaneous implantation of MDA-MB231 cells into SCID mice. In conclusion, these results suggest that PAF, produced and released by breast cancer cells, can contribute to tumor development by enhancing cell motility and proliferation and by stimulating the angiogenic response.
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PMID:PAF produced by human breast cancer cells promotes migration and proliferation of tumor cells and neo-angiogenesis. 1107 30

Research on synthetic peptides at the Institute for Drug Research (IDR) is exemplified by an overview of the projects that resulted in significant results. The first synthesis of oxytocin, a pituitary hormone, in 1953 launched the research on synthetic peptides all over the world. This synthesis was reproduced by Bodanszky at the IDR in 1954, then, after some improvements, the process was presented to Richter to produce synthetic oxytocin for therapeutic purposes. Significant result was the first synthesis of the 39-member whole molecule of human ACTH, another pituitary hormone. A short SAR study on luteinizing hormone-releasing hormone (LHRH) led to an interesting analog, Cit-8-LHRH, and somewhat later, to the D-Cit-6-LHRH analogues, of which SB-75 become marketed under the name Cetrorelix. Studies on the brain peptides, enkephalins, resulted in GYKI-14,238, the first analog that showed analgesic activity upon systemic administration and whose human efficacy could also be proven during clinical examination. Significant results were also achieved in the research on anticoagulant peptides. The first highly potent peptide aldehyde inhibitor of thrombin, GYKI-14,166, was identified at the IDR as well as its stable analog, GYKI-14,766. This compound was selected for detailed preclinical study, licensed to Eli Lilly Company, got the generic name efegatran, and entered clinical trials. The first non-covalent peptide inhibitor of thrombin, GYKI-14,525, was also identified at the IDR. Thus IDR really provided the prototype of original thrombin inhibitors in the mid 70's, and analogues were prepared in many laboratories through two decades. IDR's current research program's objective includes a quest for peptide originals that can inhibit both thrombin and factor Xa in solution and also within plasma clots in which these enzymes are entrapped. Structures with such inhibitory profile were identified among the efegatran-related alpha-hydroxy acid and ethoxycarbonyl-amino acid derivatives. The follow-up molecules are even more promising as antithrombotics, and may also be useful for treatment of disseminated intravascular coagulation, an often fatal syndrome, so we continue working on this project.
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PMID:[Research on synthetic peptides of biological interest]. 1176 93

A 20-year old female seeking legal abortion was pregnant with gestation in the 16th week as confirmed by ultrasound. Low hemoglobin count of 8.7 g/dl showed iron deficiency which was corrected by transfusion of 2 units of packed cells. Extraamniotic termination of pregnancy was commenced, and 5 mg of prostaglandin E2 (PGE2) in 50 ml of .9% saline was administered. Abortion started 9 hours later; the placenta was removed by curettage, however, severe hemorrhaging and shock ensued. Uterine perforation was ruled out by examination. Hartmann's solution and oxytocin 40 u/l were administered iv. A clotting defect with prolonged prothrombin time, thromboplastin time, and thrombin time was implicated in the excessive bleeding. 3 units of whole blood, 4 units of fresh frozen plasma, and 6 units of platelets were used to treat the coagulopathy. The patient recovered quickly, and clotting tests became normal after 2 days. Follow-up of 1 and 6 weeks showed normal hemoglobin values. PGE2 is routinely used in middle trimester abortions, however, a twentyfold increase in maternal mortality had been reported. Clotting screens are recommended for patients undergoing abortions because of coagulopathy associated with major hemorrhage.
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PMID:Coagulation defect after middle trimester abortion using prostaglandin E2 by the extra-amniotic route. 1234 67

We have previously reported that the contractile response to thrombin and trypsin was enhanced in the pregnant rat myometrium. We herein determined whether or not sex hormones contribute to this enhancement and the expression of protease-activated receptors (PARs). The nonpregnant rats received daily injections of either 17beta-estradiol or progesterone, and then the contractile response of the myometrium was examined ex vivo. Treatment with either 17beta-estradiol or progesterone had almost no significant enhancing effect on the high K(+)- or oxytocin-induced contraction. On the other hand, both 17beta-estradiol and progesterone dose-dependently enhanced the contractile response to trypsin. A maximal enhancement was obtained at 25 and 40 mg kg weight(-1) day(-1) for 17beta-estradiol and progesterone, respectively. The extent of the enhancement of the trypsin-induced contraction seen in the sex hormone-treated rats in the present study was comparable to that reported in the pregnant rats. However, the contractile response to thrombin and PAR1/PAR2-AP, SFLLRNP was not enhanced either by progesterone or 17beta-estradiol. PAR2-AP and PAR4-AP failed to induce contraction under any conditions. PAR1 mRNA was scarcely detected in the control myometrium by an RT-PCR analysis, while it slightly increased only in the progesterone-treated rats. Neither PAR2 nor PAR4 mRNA was detected. We thus conclude that the responsiveness to trypsin, but not thrombin, is controlled by sex hormones. A novel type of receptor, other than PAR1, PAR2 or PAR4, is suggested to mediate the trypsin-induced contraction as in the case of the pregnant rat myometrium.
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PMID:Enhancement of trypsin-induced contraction by in vivo treatment with 17beta-estradiol and progesterone in rat myometrium. 1605 37


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