Smad6s regulates plasminogen activator inhibitor-1 through a protein kinase C-beta-dependent up-regulation of transforming growth factor-beta.
Plasminogen activator inhibitor-1 (PAI-1) is a serpin class protease inhibitor that plays a central role in the regulation of vascular function and tissue remodeling by modulating thrombosis, inflammation, and the extracellular matrix. A central mediator controlling PAI-1 is transforming growth factor-beta (TGF-beta), which induces its expression and promotes fibrosis. We have found that a unique member of the Smad family of signal transduction molecules, Smad6s, modulates the expression of PAI-1. Overexpression of Smad6s in endothelial cells increases promoter activity and PAI-1 secretion, and an antisense to Smad6s suppresses the induction of PAI-1 by TGF-beta. The effect of Smad6s on the PAI-1 promoter appeared to be the result of increase binding of the forkhead winged helix factor FoxD1 to a TGF-beta-responsive element. Furthermore, the effect of Smad6s on PAI-1 up-regulation and on FoxD1 binding was found to result from up-regulation of TGF-beta and could be inhibited by the blocking TGF-beta signaling with Smad7. The ability of Smad6s to regulate the TGF-beta promoter and subsequent PAI-1 induction was suppressed by a selective protein kinase C-beta (PKC-beta) inhibitor. Consistent with the in vitro data, we found that increased Smad6s in diseased vessels correlated with increased TGF-beta and PAI-1 levels. Overall, our results demonstrate that the level of Smad6s can alter the level of TGF-beta and the subsequent induction of PAI-1 via a FoxD1 transcription site. Furthermore, our data suggest that this process, which is up-regulated in diseased vessels, can be modulated by the inhibition of PKC-beta.
Berg
David T
DT
Division of Biotechnology Discovery Research, Lilly Research Laboratories, Indianapolis, Indiana 46285, USA.
Myers
Laura J
LJ
Richardson
Mark A
MA
Sandusky
George
G
Grinnell
Brian W
BW
D018952:Antigens, CD34 / Q000096:biosynthesis; D002467:Cell Nucleus / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D019295:Computational Biology; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D042783:Endothelial Cells / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D051858:Forkhead Transcription Factors; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000737:chemistry; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism*; D064546:Protein Kinase C beta; D015398:Signal Transduction; D051905:Smad6 Protein; D015534:Trans-Activators / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D015854:Up-Regulation
D018952:Antigens, CD34; D004268:DNA-Binding Proteins; C500800:FOXD1 protein, human; D051858:Forkhead Transcription Factors; D016376:Oligonucleotides, Antisense; D017395:Plasminogen Activator Inhibitor 1; C497802:SMAD6 protein, human; D051905:Smad6 Protein; D015534:Trans-Activators; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D004247:DNA; D008156:Luciferases; D015500:Chloramphenicol O-Acetyltransferase; D011493:Protein Kinase C; D064546:Protein Kinase C beta