JNK regulates serotonin-mediated proliferation and migration of pulmonary artery smooth muscle cells.
JNK is a member of the MAPK family and has essential roles in inflammation and cell differentiation and apoptosis. In recent years, there have been accumulating data indicating a novel role for JNK in cell growth and migration. In this report, we demonstrate that JNK activity is necessary for serotonin (5-HT)-induced proliferation and migration of bovine pulmonary artery smooth muscle cells (PASMCs). Stimulation with 5-HT was found to lead to activation of JNK with a maximal activation at 10 min. Inhibition of JNK with its specific inhibitor, SP-600125, or its dominant-negative form, DN-JNK, significantly reduced 5-HT-stimulated [(3)H]thymidine incorporation and cyclin D1 expression. A similar inhibitory effect on SMC migration produced by 5-HT, as detected by a wound healing assay, was observed with inhibition of JNK. Furthermore, inhibition of 5-HT receptors (1B) and (2A), but not inhibition of the 5-HT transporter, blocked 5-HT-induced JNK activation. Inhibition of phosphatidylinositol 3-kinase (PI3K) with LY-294002 and wortmannin had little or no effect on 5-HT-induced JNK phosphorylation, but JNK inhibitor SP-600125 and DN-JNK blocked 5-HT-stimulated phosphorylation of Akt and its downstream effectors, p70S6K1 and S6, indicating that Akt is a downstream effector of JNK. Activation of Akt by 5-HT was blocked only minimally, if at all, by inhibitors of ERK and p38 MAPK, indicating a uniqueness of JNK MAPK in this activation of Akt. Coimmunoprecipitation showed binding of Akt to JNK, further supporting the interaction of JNK and Akt. Thus JNK is a critical molecule in 5-HT-induced PASMC proliferation and migration and may act at an important point for cross talk of the MAPK and PI3K pathways. Its activation by 5-HT is initiated through 5-HT (1B) and (2A) receptors, and its stimulation of SMC proliferation and migration occurs through the Akt pathway.
Tufts Medical Center and Tupper Research Institute, Boston, Massachusetts 02111, USA.
Lin
L
Wei
Yinglin
Y
Liu
Hideaki
H
Kaneto
Barry L
BL
Fanburg
D000818:Animals; D002417:Cattle; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004789:Enzyme Activation; D048031:JNK Mitogen-Activated Protein Kinases / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology
D012701:Serotonin; D051057:Proto-Oncogene Proteins c-akt; D048031:JNK Mitogen-Activated Protein Kinases