Foxc2 is a common mediator of insulin and transforming growth factor beta signaling to regulate plasminogen activator inhibitor type I gene expression.
Elevated plasma levels of plasminogen activator inhibitor type I (PAI-1), a significant risk factor of ischemic heart disease, are associated with insulin resistance in which insulin and transforming growth factor (TGF)-beta play a pivotal role in regulating PAI-1 production. Forkhead transcription factor FOXC2 is an important regulator of insulin resistance. However, the underlying molecular mechanisms to link FOXC2 to PAI-1 levels in insulin resistance remain to be elucidated. Here, we demonstrate that Foxc2 is a common transcriptional activator of insulin and TGF-beta signaling to directly regulate PAI-1 expression via 2 distinct target sites, an insulin response element (IRE) and a novel forkhead-binding element (FBE), adjacent to a Smad-binding site. We found that in adipocytes and endothelial cells Foxc2 mediates insulin action competing with another Forkhead protein, FOXO1, via the insulin response element, and simultaneously cooperate with the TGF-beta/Smad pathway to transactivate PAI-1. Importantly, Foxc2 haploinsufficiency in mice significantly attenuates TGF-beta1-induced PAI-1 expression in the cardiovascular system and adipose tissue. Taken together, we propose that Foxc2 is a key molecule to regulate PAI-1 gene expression.
Fujita
Hideo
H
Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232-6300, USA.
Kang
Myengmo
M
Eren
Mesut
M
Gleaves
Linda A
LA
Vaughan
Douglas E
DE
Kume
Tsutomu
T
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002478:Cells, Cultured; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000502:physiology*; D005786:Gene Expression Regulation; D006801:Humans; D007333:Insulin Resistance; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics*; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000502:physiology; D053773:Transforming Growth Factor beta1
C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D017395:Plasminogen Activator Inhibitor 1; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; C082078:mesenchyme fork head 1 protein