Plasma-derived MBL shows direct interaction with C1-inhibitor

ABSTRACT C1 inhibitor (C1INH) prevents endotoxin shock in mice via a direct interaction with lipopolysaccharide (LPS). This interaction requires the heavily glycosylated amino-terminal domain of C1INH. C1INH in which N-linked carbohydrate was removed by using N-glycosidase F was markedly less effective in protecting mice from LPS-induced lethal septic shock. N-deglycosylated C1INH also failed to suppress fluorescein isothiocyanate (FITC)-LPS binding to and LPS-induced tumor necrosis factor alpha mRNA expression by the murine macrophage-like cell line, RAW 264.7, and cells in human whole blood. In an enzyme linked immunosorbent assay, the N-deglycosylated C1INH bound to LPS very poorly. In addition, C1INH was shown to bind to diphosphoryl lipid A (dLPA) but only weakly to monophosphoryl lipid A (mLPA). As with intact LPS, binding of N-deglycosylated C1INH to dLPA and mLPA was diminished in comparison with the native protein. Removal of O-linked carbohydrate had no effect on any of these activities. Neither detoxified LPS, dLPA, nor mLPA had any effect on the rate or extent of C1INH complex formation with C1s or on cleavage of the reactive center loop by trypsin. These data demonstrate that N-linked glycosylation of C1INH is essential to mediate its interaction with the LPA moiety of LPS and to protect mice from endotoxin shock.

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Nutrient-regulated gene expression in eukaryotes

Biochemical Society Symposium ◽

10.1042/bss0730085 ◽

2006 ◽

Vol 73 ◽

pp. 85-96 ◽

Cited By ~ 8

Author(s):

Richard J. Reece ◽

Laila Beynon ◽

Stacey Holden ◽

Amanda D. Hughes ◽

Karine Rébora ◽

...

Keyword(s):

Gene Expression ◽

Rna Polymerase ◽

Rna Polymerase Ii ◽

Transcriptional Control ◽

Direct Interaction ◽

Signalling Pathways ◽

A Cell ◽

One Step ◽

Higher Eukaryotes ◽

Regulated Gene Expression

The recognition of changes in environmental conditions, and the ability to adapt to these changes, is essential for the viability of cells. There are numerous well characterized systems by which the presence or absence of an individual metabolite may be recognized by a cell. However, the recognition of a metabolite is just one step in a process that often results in changes in the expression of whole sets of genes required to respond to that metabolite. In higher eukaryotes, the signalling pathway between metabolite recognition and transcriptional control can be complex. Recent evidence from the relatively simple eukaryote yeast suggests that complex signalling pathways may be circumvented through the direct interaction between individual metabolites and regulators of RNA polymerase II-mediated transcription. Biochemical and structural analyses are beginning to unravel these elegant genetic control elements.

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Demonstration of a direct interaction between a colonic divalent cation receptor and the basolateral Na−H exchanger

Gastroenterology ◽

10.1016/s0016-5085(01)82630-5 ◽

2001 ◽

Vol 120 (5) ◽

pp. A529-A530

Author(s):

P GEIBEL ◽

M OREILLY ◽

H VIEWEGER ◽

K SIEBERT ◽

N OBREIN ◽

...

Keyword(s):

Divalent Cation ◽

Direct Interaction ◽

Cation Receptor

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Gene expression and biosynthesis of C1 inhibitor by primary human astrocytes

Immunology Letters ◽

10.1016/s0165-2478(97)88326-5 ◽

1997 ◽

Vol 56 (1-3) ◽

pp. 368

Author(s):

R Veerhuis

Keyword(s):

Gene Expression ◽

C1 Inhibitor ◽

Human Astrocytes

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Detection of both Type 1 and Type 2 Plasminogen Activator Inhibitors in Human Monocytes

Thrombosis and Haemostasis ◽

10.1055/s-0038-1645688 ◽

1990 ◽

Vol 63 (01) ◽

pp. 067-071 ◽

Cited By ~ 10

Author(s):

Joan C Castellote ◽

Enric Grau ◽

Maria A Linde ◽

Nuria Pujol-Moix ◽

Miquel LI Rutllant

Keyword(s):

Molecular Mass ◽

Plasminogen Activator ◽

Human Peripheral Blood ◽

Direct Interaction ◽

Apparent Molecular Weight ◽

Fibrinolytic System ◽

Human Monocytes ◽

Blood Monocytes ◽

Single Chain ◽

Sds Page

SummaryIncreasing evidence suggests the involvement of leukocytes in the fibrinolytic system. Monocytes secrete pro-urokinase (Grau, Thromb Res 1989; 53: 145) and it has been shown that these cells have specific receptors for urokinase and plasminogen (Miles, Thromb Haemostas 1987; 58: 936). The aim of this study was to analyse the presence of plasminogen activator inhibitor(s) in platelet-free suspensions of human peripheral blood monocytes and polymorphonuclear leukocytes (PMN). SDS-PAGE and reverse fibrin autography showed an inhibitory band of 50 kDa in the monocyte extracts (Triton X-100) but not in the PMN extracts. Urokinase (u-PA) was mixed with increasing amounts of monocyte extract for 10 min and the mixtures were added to 125Ifibrin coated wells containing plasminogen. A dose-dependent decrease in the u-PA fibrinolytic activity was observed. The amount of inhibition increased when the monocyte releasates were preincubated with u-PA (40% inhibition after 5 min preincubation and 80% after 15 min), indicating a direct interaction between this activator and an inhibitor(s). After SDS-PAGE of monocyte extracts, immunoblotting and peroxidase staining identified both PAI1 and PAI2, with an apparent molecular weight of 47-50 kDa. Monocyte-associated PAI1 formed complexes with single chain t-PA with a molecular mass 50 kDa higher than the molecular mass of the free PAI1. However, a significant amount of PAI remained unbound to t-PA. This inactive PAI1 could have come from a rapid inactivation of the primary active PAI1. These PAI1 and PAI2 detected in human monocytes may be transcendent in the regulation of the fibrinolytic system.

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Inactivation of Factor XIa in Vivo: Studies in Chimpanzees and in Humans

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650621 ◽

1996 ◽

Vol 76 (04) ◽

pp. 549-555 ◽

Cited By ~ 16

Author(s):

Walter A Wuillemin ◽

C Erik Hack ◽

Wim K Bleeker ◽

Bart J Biemond ◽

Marcel Levi ◽

...

Keyword(s):

Antithrombin Iii ◽

Life Time ◽

In Vivo Studies ◽

Clinical Samples ◽

Plasma Samples ◽

C1 Inhibitor ◽

Elimination Kinetics ◽

Factor Xia ◽

Best Parameter

SummaryC1-inhibitor (C1Inh), antithrombin III (ATIII), α1-antitrypsin (a1AT), and α2-antiplasmin (a2AP) are known inhibitors of factor XIa (FXIa). However, their precise contribution to FXIa inactivation in vivo is not known. We investigated FXIa inactivation in chimpanzees and assessed the contribution of these inhibitors to FXIa inactivation in patients with presumed FXI activation.Chimpanzees were infused with FXIa and the various FXIa-FXIa inhibitor complexes formed were measured. Most of FXIa was complexed to C1Inh (68%), followed by a2AP (13%), a1AT (10%), and ATIII (9%). Analysis of the plasma elimination kinetics revealed a half-life time of clearance (t1/2) for the FXIa-FXIa inhibitor complexes of 95 to 104 min, except for FXIa-a1AT, which had a t1/2 of 349 min. Due to this long t1/2, FXIa-a1AT complexes were predicted to show the highest levels in plasma samples from patients with activation of FXI. This was indeed shown in patients with disseminated intravascular coagulation, recent myocardial infarction or unstable angina pectoris. We conclude from this study that in vivo C1Inh is the predominant inhibitor of FXIa, but that FXIa-a1 AT complexes due to their relatively long t1/2 may be the best parameter to assess FXI activation in clinical samples.

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Defibrotide Inhibits Platelet Activation by Cathepsin G Released From Stimulated Polymorphonuclear Leukocytes

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648519 ◽

1992 ◽

Vol 67 (06) ◽

pp. 660-664 ◽

Cited By ~ 17

Author(s):

Virgilio Evangelista ◽

Paola Piccardoni ◽

Giovanni de Gaetano ◽

Chiara Cerletti

Keyword(s):

Platelet Activation ◽

Polymorphonuclear Leukocytes ◽

Direct Interaction ◽

Cathepsin G ◽

In Vivo Test ◽

Cell Functions ◽

Test Models ◽

Antithrombotic Effects

SummaryDefibrotide is a polydeoxyribonucleotide with antithrombotic effects in experimental animal models. Most of the actions of this drug have been observed in in vivo test models but no effects have been reported in in vitro systems. In this paper we demonstrate that defibrotide interferes with polymorphonuclear leukocyte-induced human platelet activation in vitro. This effect was not related to any direct interaction with polymorphonuclear leukocytes or platelets, but was due to the inhibition of cathepsin G, the main biochemical mediator of this cell-cell cooperation. Since cathepsin G not only induces platelet activation but also affects some endothelial cell functions, the anticathepsin G activity of defibrotide could help to explain the antithrombotic effect of this drug.

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The Contact Phase of Blood Coagulation in Diabetes Mellitus and in Patients with Vasculopathy

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661181 ◽

1984 ◽

Vol 52 (03) ◽

pp. 221-223 ◽

Cited By ~ 7

Author(s):

M Christe ◽

P Gattlen ◽

J Fritschi ◽

B Lämmle ◽

W Berger ◽

...

Keyword(s):

Diabetes Mellitus ◽

Molecular Weight ◽

Blood Coagulation ◽

High Molecular Weight ◽

Negative Correlation ◽

Factor Xii ◽

C1 Inhibitor ◽

High Molecular Weight Kininogen ◽

Contact Phase ◽

Α2 Macroglobulin

SummaryThe contact phase has been studied in diabetics and patients with macroangiopathy. Factor XII and high molecular weight kininogen (HMWK) are normal. C1-inhibitor and also α2-macroglobulin are significantly elevated in diabetics with complications, for α1-macroglobulin especially in patients with nephropathy, 137.5% ± 36.0 (p <0.001). C1-inhibitor is also increased in vasculopathy without diabetes 113.2 ± 22.1 (p <0.01).Prekallikrein (PK) is increased in all patients’ groups (Table 2) as compared to normals. PK is particularly high (134% ± 32) in 5 diabetics without macroangiopathy but with sensomotor neuropathy. This difference is remarkable because of the older age of diabetics and the negative correlation of PK with age in normals.

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