Mantel C, Aronica S, Luo Z, Marshall M S, Kim Y J, Cooper S, Hague N, Broxmeyer H E
Department of Medicine (Hematology/Oncology), Indiana University School of Medicine, Indianapolis 46202.
J Immunol. 1995 Mar 1;154(5):2342-50.
The immunoregulatory C-C chemokine, macrophage inflammatory protein-1 alpha (MIP-1 alpha) has suppressive activity on proliferation of stem cells and early subsets of myeloid progenitor cells. A receptor for C-C chemokines that binds MIP-1 alpha has been characterized, cloned, and shown to be related structurally to neuropeptide receptors that couple through G-proteins to phospholipase-C and adenyl cyclase. Yet, very little information on the intracellular mechanisms of action of MIP-1 alpha is available. We show here that the human factor-dependent cell line M07e is responsive to the cell cycle-suppressive effects of MIP-1 alpha, has specific membrane-binding sites for MIP-1 alpha, and that treatment of these cells with this chemokine increases the phosphatidylcholine (PC) and phosphocholine turnover rates in cells that are synergistically stimulated by the combination of granulocyte-macrophage colony-stimulating factor and steel factor but not these factors acting singly. Additional, MIP-1 alpha treatment induces a dose- and time-dependent increase in intracellular cAMP levels in M07e cells. Both exogenous PC and dibutyryl cAMP were found to suppress the proliferation of M07e colony-forming cells to a level similar to that of MIP-1 alpha, further implicating cAMP and PC metabolism in MIP-1 alpha-induced M07e suppression. RANTES, a related chemokine, with weak or incomplete binding to the cloned MIP-1 alpha receptor, did not suppress M07e colony-forming cells, nor did it increase intracellular cAMP levels, but it did enhance growth factor-induced PC turnover, further supporting the involvement of cAMP in MIP-1 alpha suppression while demonstrating that increased PC turnover alone is not sufficient for suppression. These findings support the idea that the human MIP-1 alpha receptor is coupled to phospholipid and cAMP metabolism in a manner similar to other 7-transmembrane, G-protein-linked receptors and suggest that a phosphatidylcholine hydrolytic cycle and an associated increase in cAMP are part of the mechanisms of action of MIP-1 alpha.
免疫调节性C-C趋化因子巨噬细胞炎性蛋白-1α（MIP-1α）对干细胞和髓系祖细胞早期亚群的增殖具有抑制活性。一种与MIP-1α结合的C-C趋化因子受体已得到鉴定、克隆，并显示在结构上与通过G蛋白与磷脂酶-C和腺苷酸环化酶偶联的神经肽受体相关。然而，关于MIP-1α细胞内作用机制的信息非常少。我们在此表明，人因子依赖性细胞系M07e对MIP-1α的细胞周期抑制作用有反应，具有MIP-1α的特异性膜结合位点，并且用这种趋化因子处理这些细胞会增加粒细胞-巨噬细胞集落刺激因子和Steel因子联合协同刺激但非单独作用这些因子的细胞中磷脂酰胆碱（PC）和磷酸胆碱的周转率。此外，MIP-1α处理可诱导M07e细胞内cAMP水平呈剂量和时间依赖性增加。发现外源性PC和二丁酰cAMP均能将M07e集落形成细胞的增殖抑制到与MIP-1α相似的水平，进一步表明cAMP和PC代谢参与MIP-1α诱导的M07e抑制。RANTES是一种相关趋化因子，与克隆的MIP-1α受体结合较弱或不完全，它既不抑制M07e集落形成细胞，也不增加细胞内cAMP水平，但它确实增强了生长因子诱导的PC周转率，进一步支持cAMP参与MIP-1α抑制，同时表明仅PC周转率增加不足以产生抑制作用。这些发现支持这样一种观点，即人MIP-1α受体以类似于其他7跨膜G蛋白偶联受体的方式与磷脂和cAMP代谢偶联，并表明磷脂酰胆碱水解循环和相关的cAMP增加是MIP-1α作用机制的一部分。
