Equilibrative nucleoside transporter 1 expression is downregulated by hypoxia in human umbilical vein endothelium
Equilibrative nucleoside transporter 1 expression is downregulated by hypoxia in human umbilical vein endothelium
复制标题
DOI：
10.1161/01.res.0000172568.49367.f8
复制
发表时间：
2005-07-08
影响因子：
20.1
通讯作者：
Sobrevia, L
中科院分区：
文献类型：
--
作者：
Casanello, P;Torres, A;Sobrevia, L
低氧水平（缺氧）诱导内皮功能障碍和内源性核苷腺苷的释放。人脐静脉内皮（HUVEC）在3%至5%氧的环境中发挥作用(2)，并通过人平衡核苷转运蛋白1 （hENT1）表现出高效的腺苷膜转运。我们研究了缺氧是否会改变HUVEC中腺苷转运和hENT1的表达。缺氧（0 ~ 24小时，2%和1% O(2)）降低了最大hENT1-腺苷转运速度（V(max)）和最大硝基苄基硫氨酸（NBMPR，一种高亲和力的hENT1蛋白配体）结合，但增加了细胞外腺苷浓度。缺氧也降低了hENT1蛋白和mRNA水平，N(omega)-硝基- l -精氨酸甲酯（L-NAME，一氧化氮合酶[NOS]抑制剂）或PD-98059（丝裂原活化蛋白激酶激酶1和激酶2 [MEK1/2]抑制剂）的作用不变。缺氧降低内皮细胞NOS （eNOS）活性和eNOS Ser（1177）磷酸化水平，但增加eNOS蛋白水平。缺氧增加（1 ~ 3小时），但减少（24小时）p42/44（mapk）磷酸化。因此，缺氧增加的细胞外腺苷可能是由HUVEC中hent1 -腺苷转运减少引起的。缺氧作用似乎不涉及NO，但相对快速的缺氧作用（1 ~ 3小时）可能需要p42/44（mapk）。这些结果可能对胎儿暴露于宫内缺氧环境的疾病（如宫内生长受限）或腺苷转运改变（如妊娠糖尿病）具有重要意义。
Reduced oxygen level ( hypoxia) induces endothelial dysfunction and release of the endogenous nucleoside adenosine. Human umbilical vein endothelium ( HUVEC) function in an environment with 3% to 5% O(2) and exhibit efficient adenosine membrane transport via human equilibrative nucleoside transporters 1 (hENT1). We studied whether adenosine transport and hENT1 expression are altered by hypoxia in HUVEC. Hypoxia (0 to 24 hours, 2% and 1% O(2)) reduced maximal hENT1-adenosine transport velocity (V(max)) and maximal nitrobenzylthionosine (NBMPR, a high-affinity hENT1 protein ligand) binding, but increased extracellular adenosine concentration. Hypoxia also reduced hENT1 protein and mRNA levels, effects unaltered by N(omega)-nitro-L-arginine methyl ester (L-NAME, nitric oxide synthase [ NOS] inhibitor) or PD-98059 ( inhibitor of mitogen-activated protein kinase kinase 1 and 2 [MEK1/2]). Hypoxia reduced endothelial NOS ( eNOS) activity and eNOS phosphorylation at Ser(1177), but increased eNOS protein level. Hypoxia increased (1 to 3 hours), but reduced (24 hours) p42/44(mapk) phosphorylation. Thus, hypoxia-increased extracellular adenosine may result from reduced hENT1-adenosine transport in HUVEC. Hypoxia effect seems not to involve NO, but p42/44(mapk) may be required for the relatively rapid effect (1 to 3 hours) of hypoxia. These results could be important in diseases where the fetus is exposed to intrauterine environments poor in oxygen, such as intrauterine growth restriction, or where adenosine transport is altered, such as gestational diabetes.