Endothelial cell prostaglandin E2 receptor EP4 is essential for blood pressure homeostasis
Hu Xu, Bingying Fang, Shengnan Du, Sailun Wang, Qingwei Li, Xiao Jia, Chengzhen Bao, Lan Ye, Xue Sui, Lei Qian, Zhilin Luan, Guangrui Yang, Feng Zheng, Nanping Wang, Lihong Chen, Xiaoyan Zhang, Youfei Guan
Hu Xu, Bingying Fang, Shengnan Du, Sailun Wang, Qingwei Li, Xiao Jia, Chengzhen Bao, Lan Ye, Xue Sui, Lei Qian, Zhilin Luan, Guangrui Yang, Feng Zheng, Nanping Wang, Lihong Chen, Xiaoyan Zhang, Youfei Guan
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Research Article Vascular biology

Endothelial cell prostaglandin E2 receptor EP4 is essential for blood pressure homeostasis

Abstract

Prostaglandin E2 and its cognate EP1–4 receptors play important roles in blood pressure (BP) regulation. Herein, we show that endothelial cell–specific (EC-specific) EP4 gene–knockout mice (EC-EP4–/–) exhibited elevated, while EC-specific EP4-overexpression mice (EC-hEP4OE) displayed reduced, BP levels compared with the control mice under both basal and high-salt diet–fed conditions. The altered BP was completely abolished by treatment with l–NG-nitro-l-arginine methyl ester (l-NAME), a competitive inhibitor of endothelial nitric oxide synthase (eNOS). The mesenteric arteries of the EC-EP4–/– mice showed increased vasoconstrictive response to angiotensin II and reduced vasorelaxant response to acetylcholine, both of which were eliminated by l-NAME. Furthermore, EP4 activation significantly reduced BP levels in hypertensive rats. Mechanistically, EP4 deletion markedly decreased NO contents in blood vessels via reducing eNOS phosphorylation at Ser1177. EP4 enhanced NO production mainly through the AMPK pathway in cultured ECs. Collectively, our findings demonstrate that endothelial EP4 is essential for BP homeostasis.

Authors

Hu Xu, Bingying Fang, Shengnan Du, Sailun Wang, Qingwei Li, Xiao Jia, Chengzhen Bao, Lan Ye, Xue Sui, Lei Qian, Zhilin Luan, Guangrui Yang, Feng Zheng, Nanping Wang, Lihong Chen, Xiaoyan Zhang, Youfei Guan

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Figure 5

EP4 promotes NO production via enhancing eNOS phosphorylation at Ser1177 in HUVECs.

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EP4 promotes NO production via enhancing eNOS phosphorylation at Ser1177...
(A and B) The time course (A) and the relative fluorescence intensity (B) of NO production measured by DAF-FM DA, a NO fluorescence detection probe, in HUVECs treated with CAY10580 (1 μM). *P < 0.05, **P < 0.01, and ***P < 0.001 vs. 0 minutes, n = 3. Scale bars: 50 μm. (C and D) The time course (C) and the relative fluorescence intensity (D) of NO production measured by DAF-FM DA in HUVECs treated with PGE1-OH (100 nM). *P < 0.05, **P < 0.01 and ***P < 0.001 vs. 0 minutes, n = 3–6. Scale bars: 50 μm. (E and F) The protein levels of the p-eNOS at Ser1177 and total eNOS in the mesenteric arteries of the EP4fl/fl and EC-EP4–/– mice. ***P < 0.001 vs. EP4fl/fl, n = 3. (G and H) Activation of EP4 by PGE1-OH (100 nM) increased the phosphorylation of eNOS at Ser1177 in a time-dependent manner in HUVECs. *P < 0.05, and **P < 0.01 vs. 0 minutes, n = 4. (I and J) Activation of EP4 by CAY10580 (1 μM) increased the phosphorylation of eNOS at Ser1177 in a time-dependent manner in HUVECs. *P < 0.05, and **P < 0.01 vs. 0 minutes, n = 4. (K and L) Ad-mediated EP4 overexpression increased the phosphorylation of eNOS at Ser1177 in a dose-dependent manner in HUVECs. The adenovirus was infected for 36 hours. *P < 0.05, and **P < 0.01 vs. GFP, n = 3. Data are represented as mean ± SEM; 1-way ANOVA followed by Dunnett’s multiple comparisons tests for B, D, H, J, and L; 1-way ANOVA followed by Holm-Šidák multiple comparisons test for F.