Lactoferrin binding to human platelets

Maneva, Ana; Taleva, Borislava; Manev, Vladi; Sirakov, L

doi:10.1016/0020-711x(93)90357-k

Cited by 15 publications

(10 citation statements)

References 33 publications

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“…The affinity constant of the lactotransferrin receptor is relatively low and the number of specific sites relatively high, which might be compatible with the large quantities of lactotransferrin released at specific sites during granulocyte degranulation [21]. Our results are in total disagreement with those previously obtained for platelets [37]. These authors found two binding sites with binding constants of 0.07 and 0.8 nM with 40 and 135 sites/cell respectively.…”

Section: Discussioncontrasting

confidence: 77%

“…These authors found two binding sites with binding constants of 0.07 and 0.8 nM with 40 and 135 sites/cell respectively. Scatchard plots on platelets are difficult to perform, and it is possible that their use of [59Fe]-lactotransferrin [37] instead of [12sI]lactotransferrin (in our experiments) and the quantity of platelets used (0.25-5 106 cells [37] against 10 s in our experiments) led to the difference in results. Our data are compatible with those shown in figure 3, since it would to be difficult to see a band on the Western blot if less than 200 lactotransferrin receptor molecules were present per platelet.…”

Section: Discussionmentioning

confidence: 87%

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Expression of the lactotransferrin receptor during the differentiation process of the megakaryocyte Dami cell line

Nillesse¹,

Pierce²,

Lecocq³

et al. 1994

Biology of the Cell

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In order to determine whether the human lactotransferrin receptor recently described on platelets was also present on hematopoietic precursors, we investigated its presence and characteristics on the megakaryocytic Dami cell line. The reversible binding of human 5-(([2-(carbo(hydrazino)methyl]thio)acetyl)aminofluorescein-labele d lactotransferrin showed that such a receptor was only present on the subpopulation of the largest cells. The increase in numbers of large cells during culture was paralleled by a concurrent increase in lactotransferrin receptor positive cells. Scatchard analysis of the binding of [125I]-labeled lactotransferrin showed that a single affinity class of binding site was present (Kd = 446 +/- 40 nM) and that there were 52 +/- 3 x 10(5) sites per cell. The mouse monoclonal antibody DP5B3G10, specific for the human lactotransferrin receptor, allowed its characterization as a 105 kDa protein on Western blots. The same monoclonal antibody was used to separate the small and large cell subpopulations of Dami cells by panning. Separate culture of the small cells showed that the receptor appeared prior to and independent from endomitosis. In contrast, GPIb was expressed only by large megakaryocytes. The use of conditioned medium from cultures of whole Dami cell populations indicated that a soluble factor is involved in differentiation, but not in the appearance of the lactotransferrin receptor.

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Section: Discussioncontrasting

confidence: 77%

Section: Discussionmentioning

confidence: 87%

Expression of the lactotransferrin receptor during the differentiation process of the megakaryocyte Dami cell line

Nillesse¹,

Pierce²,

Lecocq³

et al. 1994

Biology of the Cell

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“…Optimum binding was attained at 37 °C, pH 7.0-7.4 with an apparent K d of 6.0 pM for the higher-affi nity binding site [116]. The KRDS tetrapeptide, which corresponds to loop 39-42 of the hLf molecule, was found to be an integral part of the PL-LfR binding site, and to inhibit platelet aggregation [116,117]. The 50% inhibition (IC 50 ) of the N-terminal tryptic fragment was 2 µM, and the C-terminal tryptic hLf fragment did not show any inhibition.…”

Section: Platelet Lfr (Pl-lfr)mentioning

confidence: 99%

Lactoferrin

Suzuki

López

Lönnerdal

2005

Cell. Mol. Life Sci.

321

107

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Mammalian lactoferrin (Lf) receptors are suggested to have pivotal roles for mediating multiple functions of Lf. In this review, we focus on current knowledge of the structure and function of mammalian Lf receptors, mainly the first cloned Lf receptor that has been shown to be expressed in the infant small intestine at high levels but also in virtually all other tissues. The small intestinal Lf receptor takes up iron from Lf into cells and presumably exerts other physiological functions. Other Lf receptors in various tissues have also been reported to mediate some functions of Lf, such as modulating immune function, inhibiting platelet aggregation and enhancing collagen gel contractile strength. The detailed mechanisms behind the receptor-Lf interactions still need to be elucidated.

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“…Platelet-rich plasma was separated by centrifugation at 400 g for 10 min, followed by centrifugation for 15 min at 1100 g to obtain platelets. 17 After washing three times with 1 mM EDTA/phosphate-buffered saline (PBS), pH 7.4, and once with PBS, pH 7.4, platelets were suspended in 50 mM PBS 17 to a fi nal concentration of 2.5×10 6 cells/ml. All the procedures described were carried out at room temperature.…”

Section: Isolation Of Plateletsmentioning

confidence: 99%

Influence of Platelet Aggregation Modulators on Cyclic AMP Production in Human Thrombocytes

Boyanov

Maneva

2018

Folia Medica

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Background: Cyclic AMP is a powerful inhibitor of platelet aggregation. In the present study we examined the effect of platelet aggregation modulators on cyclic AMP content in human thrombocytes. Of the agents we tested, lactoferrin, wortmannin, quercetin and amiloride are platelet aggregation inhibitors, whereas ouabain is a platelet activator. Aim: To investigate the effect of lactoferrin, wortmannin, quercetin, ouabain and amiloride applied alone and in combination with lactoferrin on cyclic AMP production in human platelets. Materials and methods: ‘Direct cAMP ELISA kit’ was used for cyclic AMP determination. Results: The studied modulators, individually or in combination, stimulate cyclic AMP production in platelets. Conclusions: Wortmannin, quercetin, ouabain and amiloride increase cyclic AMP level in human platelets. Lactoferrin also increases cyclic AMP level, but the effect is statistically insignificant, which shows that lactoferrin does not participate directly in the cyclic AMP signaling. Lactoferrin additionally augments the stimulating action of wortmannin, quercetin, ouabain and amiloride on the cyclic AMP production. This probably shows a synergetic interference of lactoferrin in signal pathways along with phosphatidylinositol 3-kinase (wortmannin), quercetin (control over protein kinases, the redox state of the cell and ion transport), ouabain and amiloride (mechanisms of ion transport and phosphorylation).

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Lactoferrin binding to human platelets

Cited by 15 publications

References 33 publications

Expression of the lactotransferrin receptor during the differentiation process of the megakaryocyte Dami cell line

Expression of the lactotransferrin receptor during the differentiation process of the megakaryocyte Dami cell line

Lactoferrin

Influence of Platelet Aggregation Modulators on Cyclic AMP Production in Human Thrombocytes

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