Thrombin Anion‐binding Exosite Interactions with Heparin and Various Polyanionsa

Fenton, John W.; Witting, Joyce I.; Pouliott, Craig; Fareed, Jawed

doi:10.1111/j.1749-6632.1989.tb22499.x

Cited by 43 publications

(22 citation statements)

References 33 publications

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“…Therefore, these results suggest that heparin suppresses ET-1 production through an EDNO-cGMP mediated pathway. Heparin shows a potent anticoagulant action through inactivation of thrombin by activating antithrombin III in a serum (34) or by direct interaction with anion-binding exosite ofthrombin (35). This study has been done under a serum-free condition, and furthermore, heparin enhanced thrombin-induced cGMP production and did not suppress ET-1 production in the presence of LNMMA.…”

Section: Discussionmentioning

confidence: 99%

Heparin regulates endothelin production through endothelium-derived nitric oxide in human endothelial cells.

et al. 1993

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Heparin shows blood pressure lowering effect in hypertensive patients and animal models. The present study examined the effect of heparin on vasoconstrictor endothelin-1 (ET-1) production in cultured human umbilical vein endothelial cells (ECs) to elucidate the mechanism of antihypertensive effect of heparin. Heparin suppressed both basal and thrombin-stimulated ET-1 mRNA expression paralleled with a decrease in ET-1 peptide release in a dose-dependent manner. Heparin concomitantly enhanced nitric oxide (NO) formation measured by N02/ NO3 levels and cGMP production in ECs. These enhancements were more marked when ECs were stimulated by thrombin. However, these heparin's effects were blunted in the presence of endothelium-derived nitric oxide (EDNO) synthesizing inhibitor NG-monomethyl L-arginine. Therefore, these results suggest that suppression of ET-1 production by heparin is EDNO

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Section: Discussionmentioning

confidence: 99%

Heparin regulates endothelin production through endothelium-derived nitric oxide in human endothelial cells.

et al. 1993

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“…10 However, it has been shown that heparin can also inhibit conversion of fibrinogen into fibrin by direct interaction with anion-binding exosite of thrombin. 11 Heparin also has a variety of inhibitory actions on vascular smooth muscle cells, including inhibition of cell proliferation and migration, 12 -13 inhibition of proto-oncogene (c-fos, c-myc) induction, 14 and inhibition of collagenase 15 and tissuetype plasminogen activator 16 gene expression. Therefore, the present study was designed to examine the effects of heparin on the basal and stimulated biosynthesis and release of ET-1 by thrombin and other agonists.…”

Section: Heparin Has An Inhibitory Effect On Endothelin-1 Synthesis Amentioning

confidence: 99%

“…It has been demonstrated that heparin, like anionic polymers, could potentially inhibit a-thrombin in the conversion of fibrinogen into fibrin by its direct interaction with anion-binding exosite of thrombin composed of clustered arginines and lysines." This region, although independent of the catalytic site, interacts with heparin, 11 heparan sulfate, dermatan sulfate, dextran sulfate, and more specifically with hirudin. In this study, we have shown that hirudin fragment, 17 which is a more potent and specific thrombin inhibitor than heparin, completely blocks the thrombin-induced ET-l-LI release from endothelial cells.…”

Section: Bar Graph Shows Effect Of Heparin On Endothelin-1-like Immunmentioning

confidence: 99%

Heparin has an inhibitory effect on endothelin-1 synthesis and release by endothelial cells.

et al. 1993

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We studied the inhibitory effects of heparin on basal and agonist-induced endothelin-1 biosynthesis and release from cultured bovine endothelial cells. Heparin dose-dependently and similarly inhibited endothelin-1 release, inositol trisphosphate production, and intracellular free Ca 2+ levels stimulated by thrombin. Hirudin fragment had an inhibitory effect on thrombin-induced endothelin-1 release, whereas anti-thrombomodulin antibody had no effect. Heparin completely blocked phorbol ester-induced endothelin-1 release, whereas it had a partial inhibitory effect on endothelin-1 release stimulated by angiotensin and vasopressin. Northern blot analysis using complementary DNA for bovine preproendothelin-1 as a probe revealed that heparin reduced not only the basal but also the stimulated expression of preproendothelin-1 messenger RNA by thrombin and phorbol ester. These data suggest that heparin, in addition to its antithrombin effect, has an inhibitory effect on the biosynthesis and release of endothelin-1, possibly by inhibiting protein kinase C-dependent pathway. (Hypertension 1993;21:353-358) KEY WORDS • endothelins • thrombin • heparin • protein kinase C • RNA, messenger • endothelium E ndothelin-1 (ET-1) is a potent vasoconstrictor/ pressor peptide initially isolated from the supernatant of cultured porcine endothelial cells.

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“…2b). Based on the pub lished Kj of hirugen and glycosaminoglycans for a-thrombin [20,[24][25][26], any endogenous a-thrombin would essentially have been sat urated with hirugen or the pentasaccharide at the highest concentrations used. Because free factor Xa was converted into factor Xa-ATIII by heparin, suppression of factor Xa-ATIII formation represented direct inhibi tion of factor X activation by the polyanion under study.…”

Section: Methods Results and Discussionmentioning

confidence: 99%

“…While both the reactions of a-thrombin and ythrombin with antithrombin III are cata lyzed by heparin, a higher catalytic effect of heparin is associated with former reaction [19], Unfractionated and LMW heparins, dermatan sulfate and dextran sulfate inhibit the release of fibrinopeptide A by a-thrombin. The K;s vary from < 1 nM for dextran sulfate to ~ 20 \iM for dermatan sulfate and low-molecular-weight heparins [20], Finally, fibrin moderates the catalytic activity of heparin on thrombin inhibition by anti thrombin III (ATIII) [21,22]. It is evident from the above that the interactions of the anion-binding exosites of a-thrombin with heparin can have a profound influence on the reactivity of the enzyme with at least one substrate (fibrinogen) and one inhibitor (ATIII).…”

Section: Introductionmentioning

confidence: 99%

Modulation of the Enzymatic Activity of α-Thrombin by Polyanions: Consequences on Intrinsic Activation of Factor V and Factor VIII

Ofosu

1991

Pathophysiol Haemos Thromb

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The polyanions heparin and dermatan sulfate catalyze α-thrombin inhibition and can delay the onset of factor VIII and factor V necessary for intrinsic prothrombin activation to begin in plasma. These polyanions bind α-thrombin at its anion-binding exosite(s), structural domain(s) occupancy of which may alter the properties of the fibrin(ogen) recognition exosite of α-thrombin. We compared how such four polyanions influenced factor VIII and factor V activation during intrinsic coagulation. A pentasaccharide with high affinity for antithrombin III and the C-terminal docedapeptide fragment of hirudin (hirugen) which occupy the anion-binding and fibrin(ogen) recognition exosites of α-thrombin, respectively, could not significantly inhibit factor VIII and factor V activation. In contrast, heparin and a bis-lactobionic acid, both of which catalyzed α-thrombin inhibition, could effectively inhibit factor VIII and factor V activation. These results suggest that occupancy of fibrin(ogen) or anionbinding exosites by itself does not provide a necessary and sufficient condition for catalysis of thrombin inhibition or the inhibition thrombin-mediated amplification reactions.

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Thrombin Anion‐binding Exosite Interactions with Heparin and Various Polyanionsa

Cited by 43 publications

References 33 publications

Heparin regulates endothelin production through endothelium-derived nitric oxide in human endothelial cells.

Heparin regulates endothelin production through endothelium-derived nitric oxide in human endothelial cells.

Heparin has an inhibitory effect on endothelin-1 synthesis and release by endothelial cells.

Modulation of the Enzymatic Activity of α-Thrombin by Polyanions: Consequences on Intrinsic Activation of Factor V and Factor VIII

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