Liao F, Rabin R L, Yannelli J R, Koniaris L G, Vanguri P, Farber J M
Laboratory of Clinical Investigation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Exp Med. 1995 Nov 1;182(5):1301-14. doi: 10.1084/jem.182.5.1301.
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.
Mig是CXC亚家族的一种趋化因子，通过对从淋巴因子激活的巨噬细胞制备的cDNA文库进行差异筛选而发现。Mig基因在巨噬细胞和其他细胞中可被干扰素（IFN）-γ诱导。我们已用编码人Mig的cDNA转染了中国仓鼠卵巢（CHO）细胞，并从中获得了CHO细胞系，从中纯化出重组人Mig（rHuMig）。rHuMig可诱导人肿瘤浸润性T淋巴细胞（TIL）以及培养的、活化的人外周血来源淋巴细胞中[Ca2+]i的短暂升高。在人中性粒细胞、单核细胞或爱泼斯坦-巴尔病毒转化的B淋巴母细胞系中未观察到反应。通过改良的Boyden小室试验，rHuMig对TIL具有趋化作用，但对中性粒细胞或单核细胞没有趋化作用。SDS-PAGE显示，CHO细胞系、IFN-γ处理的人外周血单核细胞以及人单核细胞系THP-1经IFN-γ处理的细胞均分泌多种且相同的HuMig蛋白。使用CHO来源的rHuMig，我们已表明该蛋白的异质性是由于碱性羧基末端残基处的蛋白水解切割所致，并且蛋白水解发生在CHO细胞分泌rHuMig之前而非之后。分泌的rHuMig的主要种类长度在78至103个氨基酸之间，后者对应于从HuMig cDNA预测的全长分泌蛋白。在钙流试验中，与全长rHuMig相比，羧基末端截短形式的rHuMig比活性较低，并且截短的种类不阻断全长种类的活性。HuMig可能在T细胞迁移中起作用，也许在活化T细胞生理学的其他方面也起作用。
