| Abstract: |
Human interferon-inducible protein 10 (IP-10), a member of the family of the small secreted proteins called intercrine cytokines or chemokines, is secreted by interferon γ-stimulated T cells, monocytes, endothelial cells, and keratinocytes. We have begun to explore the biological properties of IP-10 by cloning and overexpression in baculovirus and in bacterial protein expression systems. A 9.9-kD protein was secreted by infected insect cells, which on sodium dodecyl sulfate-polyacrilamide gel electrophoresis comigrated with keratinocyte IP-10 and with f(22-98), a bacterial recombinant fragment lacking the signal sequence but containing all other residues of IP-10. All three reacted with antibodies recognizing residues 10-98 (αIP-10) and 77-98 of IP-10 (α22), demonstrating that it is secreted by keratinocytes and insect cells after removal of the signal sequence but without proteolysis of the COOH-terminal end. Purified riP-10 suppresses in vitro colony formation by early human bone marrow progenitor cells which need r-steel factor (rSLF) and rGM-CSF or rSLF and r-erythropoeitin (rEPO). The inhibition is dose dependent, is complete at concentrations ≥50 ng/ml, is prevented by preincubation of rIP-1O with αIP-10, but not by α22, and is seen with highly purified CD34+ cells, suggesting direct effect of rIP-10 on the progenitors. Combination of riP-10 and other chemokines at inactive concentrations inhibited colony formation in a synergistic manner, riP-10 did not affect colony formation in the absence of any growth factors or in the presence of rEPO or rGM-CSF but in absence of rSLF. The effects of IP-10 may be relevant to normal marrow function and might be harnessed to protect human hematopoietic progenitors from the cytotoxic effects of chemotherapy. © 1993, Rockefeller University Press., All rights reserved. |
| Keywords: |
nonhuman; t lymphocyte; animal; cells, cultured; erythropoietin; carboxy terminal sequence; granulocyte macrophage colony stimulating factor; keratinocyte; cloning, molecular; cytokine; cytokines; amino acid sequence; molecular sequence data; protein purification; protein synthesis; recombinant proteins; hematopoietic stem cells; immunoblotting; base sequence; hematopoiesis; hematopoietic stem cell; monocyte; cell stimulation; t lymphocyte activation; in vitro; colony forming unit gm; polyacrylamide gel electrophoresis; oligodeoxyribonucleotides; colony formation; baculovirus; baculoviridae; colony forming unit gemm; moths; human; priority journal; article; support, non-u.s. gov't; support, u.s. gov't, p.h.s.; support, u.s. gov't, non-p.h.s.
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