Abstract
In undisturbed bone marrow, most hemopoietic stem cells are nonproliferating despite the presence of multiple growth factors. Endogenous inhibitory factors are responsible for maintenance of this quiescence. Previously we sequenced and synthesized the inhibitory pentapeptide pGlu-Glu-Asp-Cys-Lys (pEEDCK), which originally derives from granulocytes, and investigated the role of this peptide in stem cell quiescence. To provide some mechanistic insight, in the present work we studied the structural relationship of this peptide to specific growth-factor-derived sequence motifs. In the murine system in vivo as well as in long-term bone marrow, antiserum to pEEDCK produced a significant stimulation of formation of colony-forming units-granulocyte/macrophage. Binding of peptides to proteins often takes place at hydropathically complementary sites. Therefore, we searched for peptides corresponding to the complementary sequence to pEEDCK. We identified antisense sequences in the genes of various cytokines and cytokine receptors including interleukin-11. The corresponding peptide Val-Leu-Leu-Thre-Arg (VLLTR) and several other peptides hydropathically complementary to pEEDCK were synthesized. We found that pEEDCK binds specifically to these peptides as well as to complete interleukin-11. Dissociation constants were in the 10 μM range. The peptide hydropathically corresponding to pEEDCK (VLLTR) was found to stimulate colony-forming units-granulocyte/macrophage formation. Our data suggest that pEEDCK could exert a coordinating function in the hemopoietic cytokine network by binding to multiple regulatory proteins and modulating their activity.
Footnotes
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Send reprint requests to: Dr. Johanna B. Paukovits, Institute for Tumorbiology-Cancer Research, University of Vienna, Borschkegasse 8a, A-1090 Vienna, Austria. E-mail:walter.paukovits{at}univie.ac.at
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This work was supported by a grant from the Austrian Foundation for Scientific Research. We gratefully acknowledge the additional financial support by the Hertzfelder Foundation, the Hochschuljubiläums-Foundation, Vienna, and the Jubiläumsfond of the National Bank, Austria (Project No. 5921).
- Abbreviations:
- pEEDCK
- pyroGlu-Glu-Asp-Cys-Lys
- VLLTR
- Val-Leu-Leu-Thre-Arg, peptide complementary to pEEDCK
- IL
- interleukin
- GM-CSF
- granulocyte-macrophage-colony-stimulating-factor
- LTBMCs
- long-term-bone-marrow-cultures
- CFU-GM
- colony-forming units-granulocyte/macrophage
- CFU-S
- colony-forming unit-spleen
- SCF
- stem cell factor
- FMOC
- fluorenylmethyloxycarbonyl
- tbs
- S-tert-butyl-sulfenyl-group
- FU
- 5-fluoro-uracil
- ara-C
- 1-β-d-arabinofuranosylcytosine
- TGF-β
- transforming growth factor-β
- MIP-1α
- macrophage inflammatory protein-1α
- Received July 27, 1998.
- Accepted May 17, 1999.
- The American Society for Pharmacology and Experimental Therapeutics
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