Post-Transcriptional Regulation of Endothelial Nitric Oxide Synthase Expression by Polypyrimidine Tract–Binding Protein 1. Issue 10 (October 2015)

• Record Type: Journal Article
• Authors: Yi, Bing; Ozerova, Maria; Zhang, Guan-Xin; Yan, Guijun; Huang, Shengdong; Sun, Jianxin
• Is Part Of: Arteriosclerosis, thrombosis, and vascular biology. Volume 35:Issue 10(2015)
• Publication Date: 2015-10
• Subjects: endothelium -- luciferase -- RNA stability -- tumor necrosis factor-α -- vascular diseases; Arteriosclerosis -- Periodicals; Thrombosis -- Periodicals; Blood-vessels -- Pathophysiology -- Periodicals; Electronic journals; 616.13
• DOI: 10.1161/ATVBAHA.115.305750
• Languages: English
• ISSNs: 1079-5642

Abstract

Abstract : Objective—: Endothelial nitric oxide synthase (eNOS) is an important regulator of vascular function and its expression is regulated at post-transcriptional levels through a yet unknown mechanism. The purpose of this study is to elucidate the post-transcriptional factors regulating eNOS expression and function in endothelium. Approaches and Results—: To elucidate the molecular basis of tumor necrosis factor (TNF)-α–mediated eNOS mRNA instability, biotinylated eNOS 3′-untranslational region (UTR) was used to purify its associated proteins by RNA affinity chromatography from cytosolic fractions of TNF-α-stimulated human umbilical vein endothelial cells (HUVECs). We identified 2 cytosolic proteins, with molecular weight of 52 and 57 kDa, which specifically bind to eNOS 3′-UTR in response to TNF-α stimulation. Matrix-assisted laser desorption ionization time-of-flight mass spectrometric analysis identified the 57-kDa protein as polypyrimidine tract–binding protein 1 (PTB1). RNA gel mobility shift and UV cross-linking assays demonstrated that PTB1 binds to a UCUU-rich sequence in eNOS 3′-UTR, and the C-terminal half of PTB1 is critical to this interaction. Importantly, PTB1 overexpression leads to decreased activity of luciferase gene fused with eNOS 3′-UTR as well as reduced eNOS expression and activity in human ECs. In HUVECs, we show that TNF-α markedly increased PTB1 expression, whereas adenovirus-mediated PTB1 overexpression decreased eNOS mRNA stability and reduced protein expression and endothelium-dependent relaxation. Furthermore, knockdown of PTB1 substantially attenuated TNF-α-induced destabilization of eNOS transcript and downregulation of eNOS expression. Conclusions—: These results indicate that PTB1 is essential for regulating eNOS expression at post-transcriptional levels and suggest a novel therapeutic target for treatment of vascular diseases associated with inflammatory endothelial dysfunction. Abstract : Supplemental Digital Content is available in the text.