Mechanisms underlying TGF-beta1-induced expression of VEGF and Flk-1 in mouse macrophages and their implications for angiogenesis.
TGF-beta induces vascular endothelial growth factor (VEGF), a potent angiogenic factor, at the transcriptional and protein levels in mouse macrophages. VEGF secretion in response to TGF-beta1 is enhanced by hypoxia and by overexpression of Smad3/4 and hypoxia-inducible factor-1alpha/beta (HIF-1alpha/beta). To examine the transcriptional regulation of VEGF by TGF-beta1, we constructed mouse reporters driven by the VEGF promoter. Overexpression of HIF-1alpha/beta or Smad3/4 caused a slight increase of VEGF promoter activity in the presence of TGF-beta1, whereas cotransfection of HIF-1alpha/beta and Smad3/4 had a marked effect. Smad2 was without effect on this promoter activity, whereas Smad7 markedly reduced it. Analysis of mutant promoters revealed that the one putative HIF-1 and two Smad-binding elements were critical for TGF-beta1-induced VEGF promoter activity. The relevance of these elements was confirmed by chromatin immunoprecipitation assay. p300, which has histone acetyltransferase activity, augmented transcriptional activity in response to HIF-1alpha/beta and Smad3/4, and E1A, an inhibitor of p300, inhibited it. TGF-beta1 also increased the expression of fetal liver kinase-1 (Flk-1), a major VEGF receptor, and TGF-beta1 and VEGF stimulated pro-matrix metalloproteinase 9 (MMP-9) and active-MMP-9 expression, respectively. The results from the present study indicate that TGF-beta1 can activate mouse macrophages to express angiogenic mediators such as VEGF, MMP-9, and Flk-1.
Jeon
Seong-Hyun
SH
Department of Molecular Bioscience, School of Bioscience and Biotechnology, Kangwon National University, Chunchon, Korea.
Chae
Byung-Chul
BC
Kim
Hyun-A
HA
Seo
Goo-Young
GY
Seo
Dong-Wan
DW
Chun
Gie-Taek
GT
Kim
Nam-Soo
NS
Yie
Se-Won
SW
Byeon
Woo-Hyeon
WH
Eom
Seok-Hyun
SH
Ha
Kwon-Soo
KS
Kim
Young-Myeong
YM
Kim
Pyeung-Hyeun
PH
D000818:Animals; D002478:Cells, Cultured; D050881:E1A-Associated p300 Protein / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D020869:Gene Expression Profiling; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000276:immunology; D020780:Matrix Metalloproteinase 9 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D018919:Neovascularization, Physiologic / Q000187:drug effects / Q000276:immunology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D051899:Smad2 Protein / Q000378:metabolism; D051900:Smad3 Protein / Q000378:metabolism; D051901:Smad4 Protein / Q000378:metabolism; D013329:Structure-Activity Relationship; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000235:genetics*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000096:biosynthesis* / Q000235:genetics*
C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A; D050881:E1A-Associated p300 Protein; C494361:Ep300 protein, mouse; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2; D020780:Matrix Metalloproteinase 9