Human Mig chemokine: biochemical and functional characterization.
Mig is a chemokine of the CXC subfamily that was discovered by differential screening of a cDNA library prepared from lymphokine-activated macrophages. The mig gene is inducible in macrophages and in other cells in response to interferon (IFN)-gamma. We have transfected Chinese hamster ovary (CHO) cells with cDNA encoding human Mig and we have derived CHO cell lines from which we have purified recombinant human Mig (rHuMig). rHuMig induced the transient elevation of [Ca2+]i in human tumor-infiltrating T lymphocytes (TIL) and in cultured, activated human peripheral blood-derived lymphocytes. No responses were seen in human neutrophils, monocytes, or Epstein-Barr virus-transformed B lymphoblastoid cell lines. rHuMig was chemotactic for TIL by a modified Boyden chamber assay but rHuMig was not chemotactic for neutrophils or monocytes. The CHO cell lines, IFN-gamma-treated human peripheral-blood monocytes, and IFN-gamma-treated cells of the human monocytic cell line THP-1 all secreted multiple and identical HuMig species as revealed by SDS-PAGE. Using the CHO-derived rHuMig, we have shown that the species' heterogeneity is due to proteolytic cleavage at basic carboxy-terminal residues, and that the proteolysis occurs before and not after rHuMig secretion by the CHO cells. The major species of secreted rHuMig ranged from 78 to 103 amino acids in length, the latter corresponding to the full-length secreted protein predicted from the HuMig cDNA. Carboxy-terminal-truncated forms of rHuMig were of lower specific activity compared to full-length rHuMig in the calcium flux assay, and the truncated species did not block the activity of the full-length species. It is likely that HuMig plays a role in T cell trafficking and perhaps in other aspects of the physiology of activated T cells.
Liao
F
F
Laboratory of Clinical Investigation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Rabin
R L
RL
Yannelli
J R
JR
Koniaris
L G
LG
Vanguri
P
P
Farber
J M
JM
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D054370:Chemokine CXCL9; D018925:Chemokines / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D019743:Chemokines, CXC; D002633:Chemotaxis; D006224:Cricetinae; D003412:Cricetulus; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007371:Interferon-gamma / Q000494:pharmacology; D008214:Lymphocytes / Q000187:drug effects*; D016246:Lymphocytes, Tumor-Infiltrating / Q000187:drug effects* / Q000378:metabolism; D016403:Lymphoma, Large B-Cell, Diffuse / Q000473:pathology; D008545:Melanoma / Q000276:immunology / Q000473:pathology; D008969:Molecular Sequence Data; D009000:Monocytes / Q000378:metabolism*; D005810:Multigene Family; D011993:Recombinant Fusion Proteins / Q000378:metabolism / Q000494:pharmacology; D014407:Tumor Cells, Cultured
C080810:CXCL9 protein, human; D054370:Chemokine CXCL9; D018925:Chemokines; D019743:Chemokines, CXC; D036341:Intercellular Signaling Peptides and Proteins; D011993:Recombinant Fusion Proteins; D007371:Interferon-gamma; D002118:Calcium