Macrophage inflammatory protein-1 alpha enhances growth factor-stimulated phosphatidylcholine metabolism and increases cAMP levels in the human growth factor-dependent cell line M07e, events associated with growth suppression.
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.
Mantel
C
C
Department of Medicine (Hematology/Oncology), Indiana University School of Medicine, Indianapolis 46202.
Aronica
S
S
Luo
Z
Z
Marshall
M S
MS
Kim
Y J
YJ
Cooper
S
S
Hague
N
N
Broxmeyer
H E
HE
D003994:Bucladesine / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D054407:Chemokine CCL4; D018946:Chemokine CCL5; D000242:Cyclic AMP / Q000378:metabolism* / Q000494:pharmacology; D016207:Cytokines / Q000494:pharmacology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008222:Lymphokines / Q000494:pharmacology; D019402:Macrophage Inflammatory Proteins; D015846:Monokines / Q000494:pharmacology*; D010713:Phosphatidylcholines / Q000378:metabolism* / Q000494:pharmacology; D010767:Phosphorylcholine / Q000494:pharmacology; D019089:Stem Cell Factor
D054407:Chemokine CCL4; D018946:Chemokine CCL5; D016207:Cytokines; D016298:Hematopoietic Cell Growth Factors; D008222:Lymphokines; D019402:Macrophage Inflammatory Proteins; D015846:Monokines; D010713:Phosphatidylcholines; D019089:Stem Cell Factor; D010767:Phosphorylcholine; D003994:Bucladesine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D000242:Cyclic AMP