Studies of the Metabolism of Asialotransferrins: Evidence that Transferrin Does not Undergo Desialylation in Vivo

Wong, K. W.; Charlwood, P. A.; Hatton, M. W. C.; Regoeczi, E.

doi:10.1042/cs0460763

Cited by 6 publications

(4 citation statements)

References 13 publications

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“…(26) who calculated similar half-lives for rabbit native fibrinogen and aglycofibrinogen in rabbits. Also, the early work of Wong et al (27) demonstrated that plasma clearance of transfenin in rabbits was independent of any preceding desialylation in vivo. we also acknowledge the technical skills of Dr. M. Smith and A.…”

Section: Discussionmentioning

confidence: 99%

Fibrinogen Has a Rapid Turnover in the Healthy Newborn Lamb

et al. 1988

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ABSTRACT. The half-lives for coagulation factors in the the response of the "fetal" fibrinogen to thrombin in vivo. Many healthy newborn infant are not known and may be different of these questions can only be asked ethically in an animal model than for the adult. We measured the half-life for fetal of newborn coagulation. We have used the sheep model to sheep fibrinogen and compared it to the half-life of adult investigate the clearance and response to thrombin of "fetal" and sheep fibrinogen. Fibrinogen was purified from adult and adult fibrinogen. Our results show that fibrinogen, whether adult fetal sheep plasma and radiolabeled with either '251 or 13'I. or fetal, has a faster turnover in the newborn compared to the The half-lives for these fibrinogens were determined in the adult and that both adult and fetal fibrinogen have a similar adult sheep and newborn lamb. In addition, the fetal and response in vivo to thrombin. adult sheep fibrinogens were compared by reptilase time, thrombin clotting time, sialic acid content, and the behavior of the N-glycans derived from these fibrinogens on the MATERIALS AND METHODS immobilized lectin, Sepharose-concanavalin A. Finally, the ~~i~~l model, plasma for purification of fibrinogen was obin vivo response of coinjected radiolabeled fibrinogens to tained from adult sheep and from fetal lambs at approximately increasing doses of infused thrombin was determined. The 100 days gestation with tern being 147 days gestation. T~ obtain fetal sheep fibrinogen differed from the adult as indicated the fetal plasma, the pregnant ewe was given an epidural anesby a prolonged reptilase time and an increased sialic acid thetic supplemented with sedative doses of sodium pentobarbital content residues/340 Kd versus adult: 8-9 by continuous intravenous infusion. The fetal lamb was partially residues1340 Kd). The latter was also reflected in differing delivered in a breech position through a uterine incision. silastic chromotographic profiles for the N-gl~cans on Se~harose-catheters were placed in the fetal lamb's femoral artery and the concanavalin A. The half-lives for both the adult and fetal fetal blood obtained. fibrinogen were significantly more rapid in the newborn Fibrinogen purification. Blood for fibrinogen purification was lamb (fetal: 47 2-0 h; adult: 46 2-4 h, mean SEM) collected into polypropylene tubes containing 3.8% sodium citthan in the adult (fetal: 116 f 6.5 h; adult: 121 f 6.9 h). rate and EACA. A fraction of the blood obtained was centrifuged Finally, the adult and fetal sheep fibrinogen responded to at 3000 x g for 20 min and multiple aliquots of the plasma thrombin in an identical fashion in the intact animal. In sample frozen at -70" c for future coagulation assay. ~h~ summary, both adult and fetal fibrinogen have faster half-remaining plasma was used for fibrinogen purification according lives in the lamb compared to the adult, despite a higher to the method of Straughn and Wagner (7). In brief, the fibrinsialic acid content for the fetal fibrinogen. We speculate ...

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Section: Discussionmentioning

confidence: 99%

Fibrinogen Has a Rapid Turnover in the Healthy Newborn Lamb

et al. 1988

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“…Numerous investigators have shown in many systems that desialylated glycoproteins, when injected into mammals, are rapidly removed from serum by this receptor in liver. However, four laboratories have shown that under normal circumstances serum glycoproteins are not desialylated in vivo and are not cleared from the circulation by this receptor (Wong et al, 1974;Clarenburg, 1983;Kuranda and Aronson, 1983;Lefort et al, 1984).…”

Section: Vertebrate Lectins and Glycoprotein Trafficmentioning

confidence: 99%

Role of Carbohydrate in Glycoprotein Traffic and Secretion

Parent¹

1988

Protein Transfer and Organelle Biogenesis

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“…The output (i.e., disappearance of human transferrin from the circulation of rat) was calculated from changes in the plasma concentration of protein-bound radioactivity as a function of time after the pulse injection of iodine-labeled human transferrin in rats. The input (i.e., the total amount of resialylated 125I-HAsTf-3 as a function of time) was computed from the integrated version of equation 16 of Norwich (15). To do so, plasma points established for the disappearance ofnormal transferrin from plasma on the one hand and for the appearance of resialylated lmI-HAsTf-3 in the circulation on the other hand were converted into continuous algebraic functions by exponential fitting.…”

Section: Methodsmentioning

confidence: 99%

“…A two-term exponential function-whose coefficients totaled unity-provided a good fit for the former and a three-term function-whose sum ofcoefficients was zero-for the latter. The computer routine (16) Studies with Tritiated N-Acetyl-D-Mannosamine. The compound was lyophilized and redissolved in 0.15 M NaCl before use.…”

Section: Methodsmentioning

confidence: 99%

Partial resialylation of human asialotransferrin type 3 in the rat.

Regoeczi¹,

Chindemi²,

Debanne³

et al. 1982

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

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After the injection of a small dose (1 jtg/100 g of body weight) of _151-labeled human asialotransferrin type 3 in rats, the radioactivity became rapidly associated with the liver. However, during the ensuing 12 hr a significant fraction of the dose returned to the circulation as protein-bound S5I. The protein released by the liver was indistinguishable by gel filtration from the original preparation and was precipitable by an antiserum to human transferrin. Nevertheless, it no longer bound to the immobilized Gal/GalN-specific lectin from rabbit liver. However, binding could be restored to a large extent by treatment with neuraminidase, indicating that the loss of binding was due to resialylation. Changes in the electrophoretic mobility of asialotransferrin released by the liver showed that resialylation was partial-i.e., it involved the attachment oftwo or three sialyl residues. From analysis by deconvolution of the plasma curve of partially resialylated asialotransferrin it was calculated that the liver "repaired" this way approximately one asialotransferrin molecule out of four. Plasma clearance of partially resialylated asialotransferrin was similar to that of nondesialylated transferrin.A minor portion (15-17%) of human transferrin phenotype C consists of molecules which, after desialylation, bind avidly (1) to the Gal/GalN-specific lectin (2) of the rat liver. We designated this fraction human asialotransferrin type 3 (HAsTf-3; ref.3). Suspended rat hepatocytes internalize HAsTf-3 via the above lectin (4). However, only a small fraction of the intracellular HAsTf-3 undergoes catabolism, whereas the rest is released showing no signs of proteolytic digestion. Cell-associated radioactivity decreases considerably more slowly in the suspension than is the time required for "2I-labeled HAsTf-3 ('"IHAsTf-3) to emerge from the hepatocytes, implying that the ligand is being repeatedly endo-and exocytosed. We termed this movement of HAsTf-3 the diacytic pathway (4) in contradistinction to the well-known lysosomal pathway for other asialoglycoproteins (5). During diacytosis, HAsTf-3 is entrapped in a subcellular particle that is ofa lesser equilibrium density than the vesicle that transports internalized asialoorosomucoid (6).The unusual handling of HAsTf-3 by the hepatocyte raises the question of how the liver ofthe intact rat ultimately disposes of this asialoglycoprotein. Because our earlier experiments in vivo were too short to provide an answer (3), we have now conducted studies lasting up to 12 hr. These showed that rat liver processed small doses of HAsTf-3 slowly in (at least) two ways-namely, catabolism and partial resialylation. Here we report our findings relating to resialylation. MATERIALS AND METHODSMaterials. Na125I, Na1311, 59FeC13, and N-acetyl-D-[6-3H(N)]mannosamine (19 Ci/mmol; 1 Ci = 3.7 X 1010 becquerels) were obtained from New England Nuclear. Neuraminidase from Vibrio cholerae was from GIBCO and neuraminidase from Diplococcus pneumoniae was a gift from M. Lowe and G. Ashwell (National ...

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Studies of the Metabolism of Asialotransferrins: Evidence that Transferrin Does not Undergo Desialylation in Vivo

Abstract: Present address:

Cited by 6 publications

References 13 publications

Fibrinogen Has a Rapid Turnover in the Healthy Newborn Lamb

Fibrinogen Has a Rapid Turnover in the Healthy Newborn Lamb

Role of Carbohydrate in Glycoprotein Traffic and Secretion

Partial resialylation of human asialotransferrin type 3 in the rat.

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