title: Monocyte chemotactic protein 1 amplifies serotonin-induced vascular smooth muscle cell proliferation.
abstract: Monocyte chemotactic protein 1 (MCP-1), which is synthesized by vascular cells, is a chemoattractant for monocytes and has been implicated in a wide range of acute and chronic inflammatory processes characterized by monocyte infiltration, including atherosclerosis. However, it is unclear whether MCP-1 is able to modulate vascular smooth muscle cell (VSMC) proliferation. We assessed the effect of MCP-1 on VSMC proliferation and its interaction with serotonin (5-HT), a mitogen for VSMCs. Growth-arrested VSMCs were stimulated with different concentrations of MCP-1 (25-200 ng/ml) and 5-HT (5 and 50 microM) in serum-free medium. DNA synthesis in VSMCs was measured by [3H]thymidine incorporation. 5-HT at concentrations of 5 and 50 microM significantly stimulated DNA synthesis by 1.8- and 2.1-fold over the control value, respectively (p < 0.0001). However, MCP-1 at the concentrations tested did not have any significant effect on DNA synthesis. Even though MCP-1 (50 ng/ml) by itself is not mitogenic, when added to 5-HT, it significantly amplified the mitogenic effect of 5-HT compared with that of 5-HT alone (p < 0.0001). The 5-HT2A receptor antagonist sarpogrelate (10 microM) and its major metabolite M-1 (0.1 microM), pertussis toxin (10 ng/ml), Src family protein tyrosine kinase (PTK) inhibitor PP2 (1 microM), protein kinase C (PKC) inhibitor Ro31-8220 (0.1 microM) and mitogen-activated protein kinase (MAPK) kinase inhibitor PD098059 (10 microM) significantly inhibited the mitogenic effect of 5-HT and its interaction with MCP-1. Anti-MCP-1 antibody (2 microg/ml) and the Janus kinase 2 (JAK2) inhibitor AG490 (10 microM) significantly inhibited the interaction of MCP-1 with 5-HT. Further, the amplified mitogenic effect of 5-HT with MCP-1 was completely reversed by the combined use of sarpogrelate with anti-MCP-1 antibody. Our results suggest that MCP-1 amplifies the mitogenic effect of 5-HT on VSMCs. The mitogenic effect of 5-HT may be mediated by the G protein-Src family PTK-PKC-MAPK pathway. The activation of the JAK2/signal transducer and activator of transcription 3 pathway by MCP-1 in addition to the MAPK pathway by 5-HT may explain the potentiating effect of MCP-1 on 5-HT-induced mitogenesis.
authors.affiliation: Department of Internal Medicine, Division of Cardiology, University of Texas-Houston Health Science Center, Houston, Tex 77030, USA.
authors.forename: T
authors.initials: T
authors.lastname: Watanabe
authors.forename: R
authors.initials: R
authors.lastname: Pakala
authors.forename: T
authors.initials: T
authors.lastname: Katagiri
authors.forename: C R
authors.initials: CR
authors.lastname: Benedict
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects*; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000276:immunology / Q000494:pharmacology*; D016895:Culture Media, Serum-Free; D004247:DNA / Q000096:biosynthesis; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D053614:Janus Kinase 2; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D037342:Pertussis Toxin; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011518:Proto-Oncogene Proteins; D011817:Rabbits; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology*; D015398:Signal Transduction; D013386:Succinates / Q000494:pharmacology; D020032:Tyrphostins / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D019061:src-Family Kinases / Q000037:antagonists & inhibitors
chemical_list: D000906:Antibodies; D018932:Chemokine CCL2; D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007211:Indoles; D011518:Proto-Oncogene Proteins; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; D013386:Succinates; D020032:Tyrphostins; D010566:Virulence Factors, Bordetella; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; C064294:sarpogrelate; D012701:Serotonin; D004247:DNA; D037342:Pertussis Toxin; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D019061:src-Family Kinases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; C064758:Ro 31-8220