Ets-1 mediates platelet-derived growth factor-BB-induced thrombomodulin expression in human vascular smooth muscle cells.
OBJECTIVE
Thrombomodulin (TM), a potent anticoagulant, is not detected in quiescent vascular smooth muscle cells (VSMCs). In diseased vessels, VSMC expresses TM, but the mechanisms are unclear. This study examined molecular mechanisms for TM expression in VSMCs.


RESULTS
Platelet-derived growth factor-BB (PDGF-BB) induced TM expression in cultured human aortic VSMCs. PDGF-induced TM is functional in activating protein C. TM induction was eliminated by inhibitors of Src kinase, phosphatidylinositol 3-kinase (PI3-kinase), and mammalian target of rapamycin (mTOR) and by expressing dominant-negative Akt while expressing active Akt-stimulated TM expression. PDGF-BB activated the TM promoter, and the deletion of a sequence segment -394/-255 drastically reduced TM promoter activity. Transcription factor E26 transformation-specific sequence-1 (Ets-1) was upregulated by PDGF-BB in a PI3-kinase- and mTOR-dependent manner. RNA interference of Ets-1 inhibited PDGF induction of TM, and overexpressing Ets-1 increased TM expression. Chromatin immunoprecipitation and electrophoretic mobility shift assay detected increased Ets-1 binding to the TM promoter after PDGF treatment. Following carotid artery ligation of C57/BL6 mice, PDGF-BB and TM were co-expressed in the media and neointima.


CONCLUSIONS
In VSMCs, PDGF-BB stimulates TM expression that is mainly mediated by Ets-1 via the Src kinase/PI3-kinase/Akt/mTOR signalling pathway. Furthermore, PDGF-BB may regulate TM expression in VSMCs during vascular remodelling.
Lo
I-Chung
IC
Institute of Basic Medical Sciences, National Cheng Kung University College of Medicine, Tainan, Taiwan, Republic of China.
Lin
Tsun-Mei
TM
Chou
Ling-Hui
LH
Liu
Shu-Lin
SL
Wu
Li-Wha
LW
Shi
Guey-Yueh
GY
Wu
Hua-Lin
HL
Jiang
Meei Jyh
MJ
D000818:Animals; D000077214:Becaplermin; D020212:Carotid Artery Injuries / Q000378:metabolism; D002478:Cells, Cultured; D004195:Disease Models, Animal; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000378:metabolism; D050784:Proto-Oncogene Protein c-ets-1 / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D020574:Proto-Oncogene Proteins c-sis; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases; D018180:Thrombomodulin / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation; D019061:src-Family Kinases / Q000378:metabolism
D000077214:Becaplermin; D048049:Extracellular Signal-Regulated MAP Kinases; D019869:Phosphatidylinositol 3-Kinases; D010982:Platelet-Derived Growth Factor; D011494:Protein Kinases; D050784:Proto-Oncogene Protein c-ets-1; D051057:Proto-Oncogene Proteins c-akt; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger; D011994:Recombinant Proteins; D058570:TOR Serine-Threonine Kinases; D018180:Thrombomodulin; D019061:src-Family Kinases; C494041:ETS1 protein, human; C546842:MTOR protein, human; C546843:mTOR protein, mouse