|
|
 Previous Article | Table of Contents | Next Article 
Human platelets as a model for the binding and degradation of
thrombopoietin
PJ Fielder, P Hass, M Nagel, E Stefanich, R Widmer, GL Bennett, GA Keller, FJ de Sauvage and D Eaton
Department of Pharmacokinetics and Metabolism, Genentech, Inc, South San
Francisco, CA 94080, USA.
Recent studies have shown that plasma thrombopoietin (TPO) levels appear to
be directly regulated by platelet mass and that removal of plasma TPO by
platelets via binding to the c-Mpl receptor is involved in the clearance of
TPO in rodents. To help elucidate the role of platelets in the clearance of
TPO in humans, we studied the in vitro specific binding of recombinant
human TPO (rhTPO) to human platelet- rich plasma (PRP), washed platelets
(WP), and cloned c-Mpl. Using a four-parameter fit and/or Scatchard
analysis, the approximate affinity of rhTPO for its receptor, which was
calculated from multiple experiments using different PRP preparations, was
between 128 and 846 pmol/L, with approximately 25 to 224 receptors per
platelet. WP preparations gave an affinity of 260 to 540 pmol/L, with
approximately 25 to 35 receptors per platelet, and erythropoietin failed to
compete with 125I-rhTPO for binding to WP. Binding and dissociation studies
conducted with a BiaCore apparatus yielded an affinity of 350 pmol/L for
rhTPO binding to cloned c-Mpl receptors. The ability of PRP to bind and
degrade 125I-rhTPO was both time- and temperature-dependent and was blocked
by the addition of excess cold rhTPO. Analysis of platelet pellets by
sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that
125I-rhTPO was degraded into a major fragment of approximately 45 to 50 kD.
When 125I-rhTPO was incubated with a platelet homogenate at pH = 7.4, a
degradation pattern similar to intact platelets was observed. Together,
these data show that human platelets specifically bind rhTPO with high
affinity, internalize, and then degrade the rhTPO.
Volume 89,
Issue 8,
pp. 2782-2788,
04/15/1997
Copyright © 1997 by The American Society of Hematology
 CiteULike  Connotea  Del.icio.us  Digg  Reddit  Technorati What's this?
This article has been cited by other articles:
|
|
|
|
 
K. Liu, R. Kralovics, Z. Rudzki, B. Grabowska, A. S. Buser, D. Olcaydu, H. Gisslinger, R. Tiedt, P. Frank, K. Okon, et al.
A de novo splice donor mutation in the thrombopoietin gene causes hereditary thrombocythemia in a Polish family
Haematologica,
May 1, 2008;
93(5):
706 - 714.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
E. Lupia, O. Bosco, S. Bergerone, A. E. Dondi, A. Goffi, E. Oliaro, M. Cordero, L. Del Sorbo, G. Trevi, and G. Montrucchio
Thrombopoietin Contributes to Enhanced Platelet Activation in Patients With Unstable Angina
J. Am. Coll. Cardiol.,
December 5, 2006;
48(11):
2195 - 2203.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
Y. Royer, J. Staerk, M. Costuleanu, P. J. Courtoy, and S. N. Constantinescu
Janus Kinases Affect Thrombopoietin Receptor Cell Surface Localization and Stability
J. Biol. Chem.,
July 22, 2005;
280(29):
27251 - 27261.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
R. Kurzrock
Thrombopoietic Factors in Chronic Bone Marrow Failure States: The Platelet Problem Revisited
Clin. Cancer Res.,
February 15, 2005;
11(4):
1361 - 1367.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
D. D. Dahlen, V. C. Broudy, and J. G. Drachman
Internalization of the thrombopoietin receptor is regulated by 2 cytoplasmic motifs
Blood,
July 1, 2003;
102(1):
102 - 108.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
I. C. Haznedaroglu, H. Goker, M. Turgut, Y. Buyukasik, and M. Benekli
Thrombopoietin as a Drug: Biologic Expectations, Clinical Realities, and Future Directions
Clinical and Applied Thrombosis/Hemostasis,
July 1, 2002;
8(3):
193 - 212.
[Abstract]
[PDF]
|
|
|
|
|
|
|
K. G. Otto, V. C. Broudy, N. L. Lin, E. Parganas, J. N. Luthi, J. G. Drachman, J. N. Ihle, and C. A. Blau
Membrane localization is not required for Mpl function in normal hematopoietic cells
Blood,
October 1, 2001;
98(7):
2077 - 2083.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
L. A. Harker, L. K. Roskos, U. M. Marzec, R. A. Carter, J. K. Cherry, B. Sundell, E. N. Cheung, D. Terry, and W. Sheridan
Effects of megakaryocyte growth and development factor on platelet production, platelet life span, and platelet function in healthy human volunteers
Blood,
April 15, 2000;
95(8):
2514 - 2522.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
E.-M. Wolber, C. Dame, H. Fahnenstich, D. Hofmann, P. Bartmann, W. Jelkmann, and J. Fandrey
Expression of the Thrombopoietin Gene in Human Fetal and Neonatal Tissues
Blood,
July 1, 1999;
94(1):
97 - 105.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
K. Cohen-Solal, N. Vitrat, M. Titeux, W. Vainchenker, and F. Wendling
High-Level Expression of Mpl in Platelets and Megakaryocytes Is Independent of Thrombopoietin
Blood,
May 1, 1999;
93(9):
2859 - 2866.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
B. Deng, N. Banu, B. Malloy, P. Hass, J. F. Wang, L. Cavacini, D. Eaton, and H. Avraham
An Agonist Murine Monoclonal Antibody to the Human c-Mpl Receptor Stimulates Megakaryocytopoiesis
Blood,
September 15, 1998;
92(6):
1981 - 1988.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
T. Kato, A. Matsumoto, K. Ogami, T. Tahara, H. Morita, and H. Miyazaki
Native Thrombopoietin: Structure and Function
Stem Cells,
September 1, 1998;
16(5):
322 - 328.
[Abstract]
[Full Text]
|
|
|
|
|
|
|
J. L. Cole, U. M. Marzec, C. J. Gunthel, S. Karpatkin, L. Worford, I. B. Sundell, J. L. Lennox, J. L. Nichol, and L. A. Harker
Ineffective Platelet Production in Thrombocytopenic Human Immunodeficiency Virus-Infected Patients
Blood,
May 1, 1998;
91(9):
3239 - 3246.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
R. Abraham and R. L. Basser
Megakaryocyte Growth and Development Factor: A Review of Early Clinical Studies
Oncologist,
October 1, 1997;
2(5):
311 - 318.
[Abstract]
[Full Text]
[PDF]
|
|
|
| |
