Baumgartner-Parzer S M, Wagner L, Reining G, Sexl V, Nowotny P, Müller M, Brunner M, Waldhäusl W
Department of Internal Medicine III, University of Vienna, Austria.
J Endocrinol. 1997 Aug;154(2):231-9. doi: 10.1677/joe.0.1540231.
Hyperthyroidism is associated with elevated plasma levels of endothelium-derived proteins such as von Willebrand factor (vWF), fibronectin (FN) and endothelin-1 (ET-1). This study was designed to characterize the mechanisms involved in this phenomenon at the cellular level. vWF, FN and ET-1 secretion and mRNA expression were measured in human umbilical vein endothelial cells (HUVECs) exposed to tri-iodothyronine (T3) for 13 +/- 1 days, using ELISA, Western blot, RIA and Northern blot analysis respectively. Exposure of HUVECs to T3 significantly increased vWF secretion (50 ng T3/ml: 117 +/- 5%, P < 0.01; 100 ng T3/ml: 127 +/- 26%, P < 0.01) as well as vWF mRNA expression (50 ng/ml: 116 +/- 13%, P < 0.001; 100 ng/ml: 136 +/- 30%, P < 0.002) (results are means +/- S.D. analysed by the Wilcoxon signed rank test). FN secretion was significantly affected by 50 (145 +/- 42% of control, P < 0.05) and 100 (116.8 +/- 16% of control, P < 0.05) ng T3/ml, and FN mRNA expression by 50 ng T3/ml (123 +/- 20%, P < 0.05). Long-term incubation with T3 increased both ET-1 secretion (25 ng/ml: 124 +/- 25%, P < 0.001; 50 ng/ml: 165 +/- 53%, P < 0.05; 100 ng/ml: 116 +/- 17%, P < 0.05) and prepro-ET-1 mRNA expression (25 ng/ml: 112 +/- 16%, P < 0.05; 50 ng/ml: 134 +/- 43%, P < 0.02; 100 ng/ml: 120 +/- 20%, P < 0.02). Protein kinase C (PKC) isoforms epsilon and beta II were not significantly affected by T3, whereas PKC alpha was increased in whole cell lysates and in membrane fractions of cells incubated with 100 but not 50 ng T3/ml. Prepro-ET-1 mRNA stability, cell numbers and proliferation, measured by [3H]thymidine assays, remained unaffected in HUVECs after exposure to T3. These data indicate thyroid hormone-induced upregulation of mRNA expression and protein synthesis of vWF, FN and ET-1, by PKC alpha-, beta II- and epsilon-independent pathways, explaining, at least in part, increased plasma concentrations of endothelial proteins and peptides in the hyperthyroid state.
甲状腺功能亢进与血浆中内皮细胞衍生蛋白水平升高有关，如血管性血友病因子（vWF）、纤连蛋白（FN）和内皮素-1（ET-1）。本研究旨在从细胞水平上阐明这一现象所涉及的机制。分别采用酶联免疫吸附测定（ELISA）、蛋白质印迹法、放射免疫分析（RIA）和Northern印迹分析法，检测人脐静脉内皮细胞（HUVECs）在三碘甲状腺原氨酸（T3）作用13±1天的条件下vWF、FN和ET-1的分泌及mRNA表达情况。HUVECs暴露于T3显著增加了vWF的分泌（50 ng T3/ml：117±5%，P<0.01；100 ng T3/ml：127±26%，P<0.01）以及vWF mRNA的表达（50 ng/ml：116±13%，P<0.001；100 ng/ml：136±30%，P<0.002）（结果为均值±标准差，采用Wilcoxon符号秩检验分析）。50（为对照的145±42%，P<0.05）和100（为对照的116.8±16%，P<0.05）ng T3/ml显著影响FN分泌，50 ng T3/ml影响FN mRNA表达（123±20%，P<0.05）。长期用T3孵育增加了ET-1的分泌（25 ng/ml：124±25%，P<0.001；50 ng/ml：165±53%，P<0.05；100 ng/ml：116±17%，P<0.05）以及前内皮素-1原mRNA的表达（25 ng/ml：112±16%，P<0.05；50 ng/ml：134±43%，P<0.02；100 ng/ml：120±20%，P<0.02）。蛋白激酶C（PKC）同工型ε和βII不受T3的显著影响，而PKCα在全细胞裂解物以及用100 ng T3/ml而非50 ng T3/ml孵育的细胞的膜组分中增加。通过[3H]胸腺嘧啶核苷测定法检测，前内皮素-1原mRNA稳定性、细胞数量及增殖在HUVECs暴露于T3后未受影响。这些数据表明甲状腺激素通过不依赖PKCα、βII和ε的途径上调vWF、FN和ET-1的mRNA表达及蛋白质合成，这至少部分解释了甲状腺功能亢进状态下血浆中内皮蛋白和肽浓度的升高。
