p53 impairs endothelial function by transcriptionally repressing Kruppel-Like Factor 2.
OBJECTIVE
To evaluate if p53 decreases Kruppel-Like Factor 2 (KLF2) expression and determine whether p53-mediated suppression of KLF2 plays a role in p53-induced endothelial dysfunction.


RESULTS
Endothelial KLF2 mediates endothelium-dependent vascular homeostasis by differentially regulating endothelial genes, leading to an anti-inflammatory and antithrombotic endothelial surface with normal vasodilatory function. In contrast, the tumor suppressor p53 leads to inflammatory gene expression and impairs endothelium-dependent vasodilatation, thus promoting endothelial dysfunction. The effect of p53 on KLF2 expression was determined. p53 inhibited KLF2 transcription in a histone deacetylase-dependent and a histone acetyltransferase-independent fashion. KLF2 expression was suppressed by p53 via a conserved p53-binding repressor sequence in its promoter. p53 bound to, and stimulated, deacetylation of Histone H3 at the KLF2 promoter. The effect of p53 on endothelial KLF2 target genes was examined. Downregulation of p53 increased expression of endothelial NO synthase and thrombomodulin and inhibited expression of plasminogen activator inhibitor 1. Conversely, overexpression of p53 suppressed endothelial NO synthase and thrombomodulin expression and stimulated plasminogen activator inhibitor 1 and endothelin-1 expression. Knockdown of KLF2 abolished the p53-induced decrease in thrombomodulin and increase in endothelin-1. Both, overexpression of p53 and knockdown of KLF2 in endothelial cells increased blood coagulation on an endothelial cell monolayer. The p53-induced increase in coagulation was rescued by forced expression of KLF2. p53 also impaired endothelium-dependent vasodilatation and decreased bioavailable vascular NO, both of which were rescued by forced KLF2 expression.


CONCLUSIONS
These findings illustrate a novel p53-dependent mechanism for the regulation of endothelial KLF2 expression. In addition, they show that downregulation of KLF2, in part, mediates a p53-stimulated dysfunctional endothelium.
University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA. Kumara@upmc.edu
Ajay
A
Kumar
Cuk-Seong
CS
Kim
Timothy A
TA
Hoffman
Asma
A
Naqvi
Jeremy
J
Dericco
Saet-Byel
SB
Jung
Zhiyong
Z
Lin
Mukesh K
MK
Jain
Kaikobad
K
Irani
D000818:Animals; D001665:Binding Sites; D001777:Blood Coagulation; D002478:Cells, Cultured; D042002:Chromatin Assembly and Disassembly; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D019332:Endothelin-1 / Q000235:genetics / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D005786:Gene Expression Regulation; D051548:Histone Acetyltransferases / Q000378:metabolism; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D051381:Rats; D011921:Rats, Inbred WKY; D020218:Response Elements; D018180:Thrombomodulin / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D014664:Vasodilation; D014665:Vasodilator Agents / Q000494:pharmacology
D019332:Endothelin-1; D006657:Histones; C096161:KLF2 protein, human; D051741:Kruppel-Like Transcription Factors; D017395:Plasminogen Activator Inhibitor 1; C051321:SERPINE1 protein, human; C546931:THBD protein, human; C495901:TP53 protein, human; D018180:Thrombomodulin; D016159:Tumor Suppressor Protein p53; D014665:Vasodilator Agents; D009569:Nitric Oxide; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D051548:Histone Acetyltransferases; D006655:Histone Deacetylases