Mechanism of endothelial nitric oxide synthase phosphorylation and activation by tentacle extract from the jellyfish Cyanea capillata.

Beilei Wang,Dan Liu,Chao Wang,Qianqian Wang,Liming Zhang,Guoyan Liu,Xia Tao,Hui Zhang

doi:10.7717/peerj.3172

Abstract

Our previous study demonstrated that tentacle extract (TE) from the jellyfish Cyanea capillata (C. capillata) could cause a weak relaxation response mediated by nitric oxide (NO) using isolated aorta rings. However, the intracellular mechanisms of TE-induced vasodilation remain unclear. Thus, this study was conducted to examine the role of TE on Akt/eNOS/NO and Ca2+ signaling pathways in human umbilical vein endothelial cells (HUVECs). Our results showed that TE induced dose- and time-dependent increases of eNOS activity and NO production. And TE also induced Akt and eNOS phosphorylation in HUVECs. However, treatment with specific PI3-kinase inhibitor (Wortmannin) significantly inhibited the increases in NO production and Akt/eNOS phosphorylation. In addition, TE also stimulated an increase in the intracellular Ca2+ concentration ([Ca2+]i), which was significantly attenuated by either IP3 receptor blocker (Heparin) or PKC inhibitor (PKC 412). In contrast, extracellular Ca2+-free, L-type calcium channel blocker (Nifedipine), or PKA inhibitor (H89) had no influence on the [Ca2+]i elevation. Since calcium ions also play a critical role in stimulating eNOS activity, we next explored the role of Ca2+ in TE-induced Akt/eNOS activation. In consistent with the attenuation of [Ca2+]i elevation, we found that Akt/eNOS phosphorylation was also dramatically decreased by Heparin or PKC 412, but not affected by Nifedipine or H89. However, the phosphorylation level could also be decreased by the removal of extracellular calcium. Taken together, our findings indicated that TE-induced eNOS phosphorylation and activation were mainly through PI3K/Akt-dependent, PKC/IP3R-sensitive and Ca2+-dependent pathways.

Highlights

Hypertension is the leading risk factor for cardiovascular diseases, causing almost 3.7% of total disability-adjusted life-years and 13% of all deaths (Park, Kario & Wang, 2015), whichHow to cite this article Wang et al (2017), Mechanism of endothelial nitric oxide synthase phosphorylation and activation by tentacle extract from the jellyfish Cyanea capillata
We demonstrated that tentacle extract (TE) from the jellyfish Cyanea capillata (C. capillata) could cause a weak relaxation response in isolated aorta rings, which might be mediated by nitric oxide (NO) (Wang et al, 2013a)
Our results showed that TE could cause a weak relaxation response, which was significantly attenuated either by the removal of the endothelium, Figure 5 Characterization of the Ca2+ concentration evoked by TE (10 μg/ml) in Fluo-4-loaded human umbilical vein endothelial cells (HUVECs). (A–G) Experimental records of the Ca2+ fluorescence image. (H–N) Statistical results of the F488/F526 ratio. (A, H) Control; (B, I) incubated with Ca2+-containing HBSS; (C, J) incubated with Ca2+-containing HBSS plus Nifedipine; (D, K) incubated with Ca2+-free HBSS; (E, L) incubated with Ca2+-free HBSS plus H89; (F, M) incubated with Ca2+-free HBSS plus Heparin; (G, N) incubated with Ca2+-free HBSS plus PKC 412

Summary

Introduction

Hypertension is the leading risk factor for cardiovascular diseases, causing almost 3.7% of total disability-adjusted life-years and 13% of all deaths (Park, Kario & Wang, 2015), whichHow to cite this article Wang et al (2017), Mechanism of endothelial nitric oxide synthase phosphorylation and activation by tentacle extract from the jellyfish Cyanea capillata. Marine natural products may become a novel pharmaceutical resource to prevent and treat various diseases. It was reported that protein hydrolysates derived from several marine organisms, such as cod (Kim et al, 2000), salmon (Ono et al, 2006), sea cucumber collagen (Zhao et al, 2009), shrimp (Zhang et al, 2009), sesame (Biswas, Dhar & Ghosh, 2010), squid skin (Lin, Shun & Li, 2011), and jellyfish (Li et al, 2014; Liu et al, 2012; Zhuang et al, 2012), could exert their hypotensive effects. Jellyfish is traditionally recognized to be beneficial in reducing blood pressure in China, its antihypertensive effect is rarely reported

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