Samuel Sherin, Zhang Kuo, Tang Yi-Da, Gerdes A Martin, Carrillo-Sepulveda Maria Alicia
Department of Life Sciences, New York Institute of Technology, Old Westbury, New York, New York, USA.
Department of Internal Medicine, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Cell Physiol Biochem. 2017;41(5):1894-1904. doi: 10.1159/000471938. Epub 2017 Apr 4.
BACKGROUND/AIMS: Vascular relaxation caused by Triiodothyronine (T3) involves direct activation of endothelial cells (EC) and vascular smooth muscle cells (VSMC). Activation of protein kinase G (PKG) has risen as a novel contributor to the vasorelaxation mechanism triggered by numerous stimuli. We hypothesize that T3-induced vasorelaxation involves PKG/vasodilator-stimulated phosphoprotein (VASP) signaling pathway in VSMC.
Human aortic endothelial cells (HAEC) and VSMC were treated with T3 for short (2 to 60 minutes) and long term (24 hours). Nitric oxide (NO) production was measured using DAF-FM. Expression of protein targets was determined using western blot. For functional studies, rat aortas were isolated and treated with T3 for 20 minutes and mounted in a wire myograph. Relaxation was measured by a concentration-dependent response to acetylcholine (ACh) and sodium nitroprusside (SNP).
Aortas stimulated with T3 exhibited augmented sensitivity to ACh and SNP-induced relaxation, endothelium-dependent and endothelium-independent responses, respectively. T3 directly increased vasorelaxation, which was abolished in the presence of a PKG inhibitor. T3 markedly induced phosphorylation of Akt, eNOS and consequently increased NO production in EC. Likewise, T3 induced phosphorylation of VASP at serine 239 via the PKG pathway in VSMC.
Our findings have uncovered a PKG/VASP signaling pathway in VSMC as a key molecular mechanism underlying T3-induced vascular relaxation.
背景/目的：三碘甲状腺原氨酸（T3）引起的血管舒张涉及内皮细胞（EC）和血管平滑肌细胞（VSMC）的直接激活。蛋白激酶G（PKG）的激活已成为由多种刺激引发的血管舒张机制的新促成因素。我们假设T3诱导的血管舒张涉及VSMC中的PKG/血管舒张剂刺激的磷蛋白（VASP）信号通路。
用人主动脉内皮细胞（HAEC）和VSMC进行短期（2至60分钟）和长期（24小时）的T3处理。使用DAF-FM测量一氧化氮（NO）的产生。使用蛋白质印迹法测定蛋白质靶点的表达。为了进行功能研究，分离大鼠主动脉并用T3处理20分钟，然后安装在血管张力描记仪中。通过对乙酰胆碱（ACh）和硝普钠（SNP）的浓度依赖性反应来测量舒张。
用T3刺激的主动脉分别对ACh和SNP诱导的舒张表现出增强的敏感性，即内皮依赖性和非内皮依赖性反应。T3直接增强血管舒张，在存在PKG抑制剂的情况下这种舒张作用被消除。T3显著诱导Akt、内皮型一氧化氮合酶（eNOS）的磷酸化，从而增加EC中NO的产生。同样，T3通过VSMC中的PKG途径诱导VASP在丝氨酸239处的磷酸化。
我们的研究结果揭示了VSMC中的PKG/VASP信号通路是T3诱导血管舒张的关键分子机制。
