Clearance of the heavy and light polypeptide chains of human tissue-type plasminogen activator in rats

Rijken, D.C.; Emeis, J.J.

doi:10.1042/bj2380643

Cited by 75 publications

(47 citation statements)

References 18 publications

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“…2 A is typical of previously reported plasma clearance curves for t-PA in rats in that the rapid phase of clearance has a half-life of about 1 min. (27,28,32,37,38). Approximately 90% of the administered dose was found in the liver at 10 min.…”

Section: Methodsmentioning

confidence: 99%

“…t-PA is used widely as a fibrinolytic agent in the treatment of acute myocardial infarction (23). One substantial limitation to the clinical use oft-PA is its rapid plasma clearance (half-life is -1-5 min), which is predominantly due to an active uptake system in the liver (24)(25)(26)(27)(28)(29)(30)(31). Recent studies using both human and rat hepatoma cells have demonstrated that LRP/a2MR is an hepatic clearance receptor for both free t-PA (21 ) and t-PA/PAI-l complexes (22).…”

Section: Methodsmentioning

confidence: 99%

“…A major drawback to the clinical use oft-PA is its rapid plasma clearance, ranging from a t, /2 of 1-4 min in rodents (24-29) to [5][6][7][8][9][10] min in humans (30,31) . In vivo clearance studies have shown that the liver is the primary organ responsible for the rapid uptake of t-PA from the circulation (24)(25)(26)(27)(28)(29)(30)(31). Studies 1.…”

Section: Introductionmentioning

confidence: 99%

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39-kD protein inhibits tissue-type plasminogen activator clearance in vivo.

Warshawsky

Bu²,

Schwartz

1993

J. Clin. Invest.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

39-kD protein inhibits tissue-type plasminogen activator clearance in vivo.

Warshawsky

Bu²,

Schwartz

1993

J. Clin. Invest.

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“…In vivo studies have shown that the liver is the major organ responsible for t-PA clearance (6)(7)(8)(9)(10)(11). Kinetic studies have suggested that specific receptors exhibiting characteristics of receptor-mediated endocytosis are involved in the clearance process.…”

Section: Mh1cj Cells Comigrated With the Large Subunit Of Lrp/a2mrmentioning

confidence: 99%

Low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor is an hepatic receptor for tissue-type plasminogen activator.

Williams

Strickland

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

300

191

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Tissue-type plasminogen activator (t-PA), a serine protease that catalyzes the initial and rate-limiting step in the fibrinolytic cascade, is cleared rapidly in vivo by the liver. Using chemical crosslinking, we have recently identified a plasminogen-activator inhibitor type 1 (PAI-1)-independent t-PA clearance receptor on rat hepatoma MH1C1 cells with a relative molecular mass of %-500 kDa. Another recently identified membrane receptor, low density lipoprotein receptorrelated protein/a2-macroglobulin receptor (LRP/a2MR), was also detected on MH1Cj hepatoma cells by using immunoprecipitation with anti-LRP/a2MR antibody. When analyzed by SDS/PAGE, we found the t-PA receptor identified on MH1Cj cells comigrated with the large subunit of LRP/a2MR.The t-PA receptor was immunoprecipitated by an anti-LRP/a2MR antibody after chemical crosslinking of specifically bound 12'I-labeled t-PA to its receptor. Through chemical crosslinking studies, we found that t-PA and methylamineactivated a2-macroglobulin could bind to LRP/a2MR simultaneously without competing with one another for binding, suggesting that the two ligands bound to two independent sites on the LRP/a2MR molecule. Furthermore, a 39-kDa protein, which modulates ligand binding to LRP/a2MR, was also found to inhibit t-PA binding to its receptor. These data thus show that the t-PA clearance receptor identified on MH1Cj hepatoma cells is LRP/a2MR.Tissue-type plasminogen activator (t-PA) plays an essential role in the fibrinolytic process by catalyzing the conversion of the zymogen plasminogen to plasmin (1,2). The plasmin thus activated can proteolytically degrade the fibrin network associated with blood clots. The role of t-PA as an initiator in thrombolysis has been exploited as a thrombolytic agent (3-5). However, the half-life of t-PA in plasma is very short, ranging from 1-4 min in rodents (6-11) to 5-10 min in humans (12, 13).In vivo studies have shown that the liver is the major organ responsible for t-PA clearance (6-11). Kinetic studies have suggested that specific receptors exhibiting characteristics of receptor-mediated endocytosis are involved in the clearance process. At least two classes of clearance mechanisms exist: a noncarbohydrate-mediated pathway via hepatocytes and a carbohydrate-mediated pathway via endothelial cells (14). In hepatocytes, detailed studies of the clearance mechanism have revealed two types of clearance receptor: plasminogenactivator inhibitor type 1 (PAI-1)-dependent (15)(16)(17)(18)(19)(20) and -independent (11,21) receptors. Recent studies from our laboratory have identified a PAI-1-independent t-PA receptor on rat hepatoma MH1C1 cells (22). Binding of t-PA to this receptor occurs predominantly via the free form and requires neither the protease active site nor the presence of bioactive PAI-1. This situation contrasts with the PAI-1-dependent t-PA receptor we have previously characterized on human hepatoma HepG2 cells, for which the predominant specificbinding species is the t-PA-PAI-1 complex (16)(17)(18)(19)22). Simi...

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“…Interruption of hepatic blood flow or hepatectomy lengthens the half-life of t-PA by as much as 20-fold (9-1 1 ). Numerous in vitro studies, moreover, have suggested that the hepatic parenchymal cell is a major site of t-PA catabolism (12)(13)(14). The well-differentiated human hepatoma cell (HepG2) has served as a useful model for studying catabolic processing of a number of proteins (15)(16)(17)(18)(19)(20)(21)(22)(23).…”

Section: Introductionmentioning

confidence: 99%

alpha-Fucose-mediated binding and degradation of tissue-type plasminogen activator by HepG2 cells.

Hajjar

Reynolds²

1994

J. Clin. Invest.

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The glycoprotein tissue-type plasminogen activator (t-PA) is subject to hepatic clearance in humans. Here, the interaction of t-PA with a well-differentiated hepatoma cell line (HepG2) was examined. Suspended HepG2 cells bound '25I-t-PA in a specific, saturable, and reversible fashion through a Ca2'-dependent, active site-independent mechanism. Binding isotherms indicated a high affinity system with a single class of saturable binding sites (Kd 39 nM; maximum binding capacity 493,000 sites per cell). Bound t-PA was rapidly degraded at 37°C in a manner inhibited by lysosomotropic agents or metabolic inhibitors. Pretreatment of t-PA with monoclonal antibodies against the EGF/fibronectin finger domain, but not kringle 2 or kringle 1, reduced total binding by 86%. Binding of 125i-t-PA to HepG2 cells was inhibited by monosaccharides fucose and galactose and by the neoglycoprotein fucosyl-albumin. Enzymatic removal of a-fucose residues, but not a-galactose, high mannose, or complex oligosaccharide from '25I-t-PA, reduced specific binding by 60±5%. Binding was also inhibited by high, but not low, molecular weight urokinase, which contains an EGF-based threonine-linked a-fucose homologous to that of t-PA. These data suggest that EGF-associated 0-linked a-fucose may mediate t-PA binding and degradation by HepG2 cells. This mechanism may be relevant to other proteins with analogous structures. (J. Clin. Invest. 1994. 93:703-710.)

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Clearance of the heavy and light polypeptide chains of human tissue-type plasminogen activator in rats

Cited by 75 publications

References 18 publications

39-kD protein inhibits tissue-type plasminogen activator clearance in vivo.

39-kD protein inhibits tissue-type plasminogen activator clearance in vivo.

Low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor is an hepatic receptor for tissue-type plasminogen activator.

alpha-Fucose-mediated binding and degradation of tissue-type plasminogen activator by HepG2 cells.

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