A role for p38 mitogen-activated protein kinase and c-myc in endothelin-dependent rat aortic smooth muscle cell proliferation.
We have demonstrated recently that endothelin (ET) stimulates rat aortic smooth muscle cell proliferation through an extracellular signal-regulated kinase (ERK)-dependent mechanism. Approximately 70% of ET-dependent [3H]-thymidine incorporation in these cells signals through this system. In the present study, we show that the residual mitogenic activity requires an intact p38 mitogen-activated protein kinase (p38 MAPK) system and increased c-myc gene expression. ET increased [3H]-thymidine incorporation in rat aortic smooth muscle cells approximately 5-fold. p38 MAPK inhibition with SB203580 or ERK/ERK kinase inhibition with PD98059 each effected approximately 70% inhibition in ET-dependent DNA synthesis, whereas the combination led to nearly complete blockade of the ET effect. ET also increased c-myc RNA levels and c-Myc protein levels in these cells. The increment in c-Myc expression was blocked by SB203580 but not by PD98059. Use of antisense oligonucleotides directed against the translation start site of the c-myc transcript, but not scrambled oligonucleotide sequence, resulted in approximately 60% decrease in ET-dependent [3H]-thymidine incorporation. The combination of antisense c-myc and PD98059 resulted in near complete inhibition of ET-dependent DNA synthesis. Both ET and c-Myc increased expression and promoter activity of E2F, a transcription factor that has been linked to enhanced cell cycle activity. The ET-dependent increment in E2F promoter activity was suppressed after treatment with SB203580 or antisense c-myc but not by PD98059 or a scrambled oligonucleotide sequence. Collectively, these findings demonstrate that ET uses 2 complementary signal transduction cascades (ERK and p38 MAPK) to control proliferative activity of vascular smooth muscle cells.
Chen
Songcang
S
Diabetes Center, University of California, San Francisco, CA 94143-0540, USA.
Qiong
Ye
Y
Gardner
David G
DG
D000818:Animals; D001011:Aorta / Q000166:cytology*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D050684:E2F Transcription Factors / Q000235:genetics / Q000378:metabolism; D016232:Endothelins / Q000494:pharmacology / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors; D015870:Gene Expression; D016259:Genes, myc; D020935:MAP Kinase Signaling System / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000187:drug effects; D016271:Proto-Oncogene Proteins c-myc / Q000502:physiology*; D051381:Rats; D013936:Thymidine / Q000037:antagonists & inhibitors / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*
D050684:E2F Transcription Factors; D016232:Endothelins; D004791:Enzyme Inhibitors; D016376:Oligonucleotides, Antisense; D016271:Proto-Oncogene Proteins c-myc; D004247:DNA; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D013936:Thymidine