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Purification and biologic characterization of plasma-derived megakaryocyte growth and development factor
1Amgen, Inc., Amgen Center, Thousand Oaks, CA 91320, USA.
Abstract:
The isolation and cloning of the ligand for the cytokine receptor, Mpl, have been recently described. In this report we present details of the purification of this novel cytokine (megakaryocyte growth and development factor [MGDF]) from aplastic canine plasma. Two forms of canine MGDF, with apparent molecular weights of 25 kD and 31 kD and sharing a common N-terminal amino acid sequence, were isolated. The sole contaminant detected in purified 25-kD or 31-kD MGDF was canine Ig. Canine MGDF is characterized as a human megakaryocyte colony-stimulating factor that acts synergistically with human recombinant stem cell factor but not interleukin-3. MGDF also appears to be physiologically regulated in response to platelet demand. In canine and murine models, serum levels of MGDF activity peak during the thrombocytopenic periods after irradiation, 5-fluorouracil, or antiplatelet antisera injections. These data indicate that the megakaryocyte-stimulating activity that accumulates in plasma in response to platelet losses is a novel cytokine that functions through an interaction with the Mpl cytokine receptor.
Insights
Researchers purified megakaryocyte growth and development factor (MGDF) from canine plasma. This novel cytokine stimulates platelet production and is regulated by platelet demand, offering insights into thrombopoiesis.
Area of Science:
- Hematology
- Molecular Biology
- Cytokine Research
Background:
- The Mpl receptor's ligand, crucial for megakaryopoiesis, was recently identified.
- Understanding the regulation and function of this novel cytokine is essential for hematological research.
Purpose of the Study:
- To detail the purification of megakaryocyte growth and development factor (MGDF) from aplastic canine plasma.
- To characterize canine MGDF and investigate its biological activity and regulation.
Main Methods:
- Purification of MGDF from canine plasma using biochemical techniques.
- Analysis of MGDF molecular weight and N-terminal amino acid sequence.
- Assessment of MGDF's synergistic effects with other growth factors and its activity in vivo.
Main Results:
- Two forms of canine MGDF (25 kD and 31 kD) were isolated, sharing a common N-terminal sequence.
- Canine MGDF acts as a human megakaryocyte colony-stimulating factor, synergizing with stem cell factor.
- MGDF serum levels increase during thrombocytopenia in response to platelet loss, indicating physiological regulation.
Conclusions:
- Canine MGDF is a novel cytokine that interacts with the Mpl receptor.
- MGDF plays a significant role in regulating platelet production in response to demand.
- These findings contribute to understanding thrombopoiesis and Mpl-mediated signaling.