A peptide derived from the amino terminus of endothelial-monocyte-activating polypeptide II modulates mononuclear and polymorphonuclear leukocyte functions, defines an apparently novel cellular interaction site, and induces an acute inflammatory response.
Endothelial-monocyte-activating polypeptide II (EMAP II) is a novel mediator isolated from conditioned medium of methylcholanthrene A-induced tumor cells which modulates properties of endothelial cells, mononuclear phagocytes (MPs), and polymorphonuclear leukocytes (PMNs) in vitro and induces an acute inflammatory response in vivo. A synthetic peptide comprising 15 residues from the N-terminal region (residues 6-20) was shown to induce directional migration of MPs and PMNs, with half-maximal effect at approximately 200-250 pM, whereas a peptide from the C terminus of EMAP II, as well as other irrelevant peptides, were without effect. Modulation of cellular phenotype by EMAP II-derived peptide was suggested by peptide-induced elevation of cytosolic free calcium concentration in fura-2-loaded MPs and PMNs and by stimulation of peroxidase release in PMNs. Consistent with these in vitro data, EMAP II-derived N-terminal peptide-albumin conjugates injected into the mouse footpad elicited inflammatory cell tissue infiltration, whereas albumin alone or EMAP II-derived C-terminal peptide conjugated to albumin incited little response. Binding of 125I-labeled EMAP II-derived peptide (residues 12-20) to MPs was saturable (Kd approximately 200 pM) and was blocked in a dose-dependent manner by the addition of intact EMAP II and unlabeled EMAP II-derived peptides (residues 6-20 and 12-20), whereas interleukin 1, tumor necrosis factor, formyl-methionyl-leucinyl-phenylalanine, or irrelevant peptides were without effect. Cross-linking of 125I-EMAP II-derived peptide (residues 12-20) by disuccinimidyl suberate to human MPs demonstrated a band, approximately 73 kDa, on reduced sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 125I-EMAP II-derived peptide also demonstrated specific binding to human PMNs and murine RAW cells. These data indicate that the N-terminal region of EMAP II defines a biologically active locus of the molecule which interacts with target cells via a potentially novel cellular receptor.
Kao
J
J
Department of Physiology, Columbia University College of Physicians and Surgeons, New York, New York 10032.
Fan
Y G
YG
Haehnel
I
I
Brett
J
J
Greenberg
S
S
Clauss
M
M
Kayton
M
M
Houck
K
K
Kisiel
W
W
Seljelid
R
R
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002461:Cell Line, Transformed; D002462:Cell Membrane / Q000378:metabolism; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D016207:Cytokines; D006801:Humans; D007249:Inflammation / Q000503:physiopathology*; D007700:Kinetics; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000502:physiology*; D008264:Macrophages; D051379:Mice; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000378:metabolism* / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology*; D009195:Peroxidase / Q000378:metabolism; D010586:Phagocytes / Q000187:drug effects / Q000502:physiology*; D011485:Protein Binding; D016601:RNA-Binding Proteins; D013329:Structure-Activity Relationship; D013925:Thromboplastin / Q000378:metabolism
D016207:Cytokines; D009363:Neoplasm Proteins; D010446:Peptide Fragments; D016601:RNA-Binding Proteins; C077219:small inducible cytokine subfamily E, member 1; D013925:Thromboplastin; D009195:Peroxidase; D002118:Calcium