Mitogenic signaling by transfected neuromedin B receptors in Rat-1 cells.
The rat neuromedin B (NMB) receptor was expressed in Rat-1 fibroblasts to elucidate the signaling pathways and mitogenic effects mediated by this seven-transmembrane domain receptor. Receptor expression was verified by ligand binding and Ca2+ mobilization, which were blocked by the NMB receptor antagonist D-Nal-Cys-Tyr-D-Trp-Orn-Val-Cys-Nal-NH2. NMB acted as a potent growth factor promoting DNA synthesis and cell proliferation in serum-free medium in Rat-1 cells transfected with the NMB receptor. Prior to DNA synthesis, NMB stimulated phosphorylation of 80K/MARCKS, a major substrate of protein kinase C, which could be prevented by the selective protein kinase C inhibitor GF 109203X. Furthermore, NMB induced a rapid p42MAPK activation and tyrosine phosphorylation of multiple proteins including p125FAK and paxillin. The half-maximal concentrations (EC50) of NMB required to induce DNA synthesis (0.7-0.9 nM) and cell proliferation (0.7-1 nM) paralleled the Kd for 125I-[D-Tyr0]NMB binding and the EC50 values for the induction of the early signaling events. Thus, NMB can activate multiple signal transduction pathways and act as a sole mitogen through its receptor expressed in Rat-1 fibroblasts.
Lach
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Imperial Cancer Research Fund, London, United Kingdom.
Broad
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Rozengurt
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D000818:Animals; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002455:Cell Division / Q000502:physiology; D002460:Cell Line / Q000201:enzymology / Q000648:ultrastructure; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D005347:Fibroblasts / Q000201:enzymology / Q000648:ultrastructure; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D008934:Mitogens / Q000494:pharmacology*; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism; D018004:Receptors, Bombesin / Q000235:genetics*; D015398:Signal Transduction / Q000502:physiology*; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism
D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D047908:Intracellular Signaling Peptides and Proteins; C000619712:Marcks protein, rat; D008565:Membrane Proteins; D008934:Mitogens; D051419:Paxillin; D010750:Phosphoproteins; D011506:Proteins; C496063:Pxn protein, rat; D018004:Receptors, Bombesin; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D014443:Tyrosine; D004247:DNA; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium