Angiotensin II induces renal plasminogen activator inhibitor-1 and cyclooxygenase-2 expression post-transcriptionally via activation of the mRNA-stabilizing factor human-antigen R.
Angiotensin (Ang) II-induced fibrosis of the kidney is characterized by the enhanced expression of profibrotic and proinflammatory genes, including the serine protease inhibitor plasminogen activator inhibitor-1 (PAI-1) and cyclooxygenase-2 (COX-2). In addition to transcriptional regulation, both genes are subject to post-transcriptional control by AU-rich destabilizing elements that reside within the 3' untranslated region of the mRNA. We demonstrated that the continuous infusion of AngII in rats induced fibrosis concomitant with a significant increase in glomerular PAI-1 and COX-2 expression levels. Using RNA pull-down assays and electromobility shift assays, we demonstrated the increased binding of the ubiquitous RNA-binding protein human-antigen R (HuR) to the mRNAs of both PAI-1 and COX-2 in the cytoplasmic fractions of renal homogenates from AngII-treated rats. Actinomycin D experiments in rat mesangial cells revealed that AngII stabilizes both mRNAs via HuR as proven by small interfering RNA. Mechanistically, AngII promotes an increase in nucleo-cytoplasmic HuR shuttling, which was blocked by the PKC inhibitor rottlerin and the type-I AngII (AT(1)) receptor antagonist valsartan but was unaffected by both AT(2) receptor antagonists PD123319 and CGP42112. Co-immunoprecipitation revealed that AngII treatment caused an increase in nuclear PKC-delta concomitant with binding to nuclear HuR both in vitro and in vivo. The post-transcriptional regulation of PAI-1 and COX-2 by PKC-delta-dependent HuR shuttling may contribute to the pathogenesis of hypertensive nephrosclerosis triggered by AngII.
Doller
Anke
A
Pharmazentrum Frankfurt/ZAFES, Klinikum der Johann Wolfgang Goethe-Universität Frankfurt am Main, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany.
Gauer
Stefan
S
Sobkowiak
Ewelina
E
Geiger
Helmut
H
Pfeilschifter
Josef
J
Eberhardt
Wolfgang
W
D000804:Angiotensin II / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; D024202:Electrophoretic Mobility Shift Assay; D005355:Fibrosis; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D006801:Humans; D006973:Hypertension / Q000150:complications; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D007674:Kidney Diseases / Q000209:etiology / Q000378:metabolism*; D008297:Male; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D012333:RNA, Messenger; D016601:RNA-Binding Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000954:Antigens, Surface; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; C098770:ELAVL1 protein, human; D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D000804:Angiotensin II; D051546:Cyclooxygenase 2