Back to Search
Start Over
Interleukin-3/erythropoietin fusion proteins: in vitro effects on hematopoietic cells.
- Source :
-
Experimental hematology [Exp Hematol] 1993 May; Vol. 21 (5), pp. 647-55. - Publication Year :
- 1993
-
Abstract
- Erythropoietin (Epo) acts synergistically with interleukin-3 (IL-3) to induce proliferation and differentiation of erythroid progenitors. This synergy occurs at IL-3 concentrations that have little or no effect alone. To determine whether optimal expansion of erythroid cells results when they are targeted by a molecule with both IL-3 and Epo activities, fusion proteins were generated and analyzed. Expression vectors were constructed in which the coding regions of human IL-3 and Epo cDNAs were joined by either a short (2 to 3 amino acids) or long (23 amino acids) linker sequence and expressed in Chinese hamster ovary (CHO) cells. Analysis of equilibrium binding properties of the IL-3 and Epo moieties revealed that in all fusion proteins each retained the ability to bind receptor. When IL-3 was connected to Epo by a short linker, the binding affinity of the IL-3 moiety was lower. In vitro proliferative activity of each moiety was observed on cell lines responsive to IL-3, Epo or a combination of the two cytokines. Fusion of IL-3 to Epo through its amino terminus was found to result in partial loss of its function. All the fusion proteins were biologically active on human bone marrow. When IL-3 was located at the amino domain of the protein, induction of erythroid colonies was similar to that of a mixture of IL-3 and Epo. These results indicate that biological integrity of both IL-3 and Epo can be maintained when these cytokines are fused, but that enhancement of erythropoiesis over that observed with a mixture of the two cytokines cannot be achieved by their fusion alone. Other requirements such as the coexpression of the IL-3 and Epo receptors and the sharing of a receptor subunit are likely to be needed for an optimal cell response to the fusion growth factors.
- Subjects :
- Animals
Base Sequence
Bone Marrow Cells
CHO Cells
Cell Differentiation
Cell Division
Cells, Cultured
Colony-Forming Units Assay
Cricetinae
DNA
Erythroid Precursor Cells cytology
Erythropoietin administration & dosage
Erythropoietin genetics
Granulocytes cytology
Humans
Interleukin-3 administration & dosage
Interleukin-3 genetics
Macrophages cytology
Molecular Sequence Data
Plasmids
Erythropoietin pharmacology
Hematopoietic Stem Cells cytology
Interleukin-3 pharmacology
Recombinant Fusion Proteins pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 0301-472X
- Volume :
- 21
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- Experimental hematology
- Publication Type :
- Academic Journal
- Accession number :
- 8513865