Uterine artery endothelium undergoes a form of functional adaptation during pregnancy because of an increase in Cx43 communication, resulting in increased Ca2+/IP3 exchange and more synchronous and sustained vasodilator production. We have shown previously that acute exposure to growth factors and TNF can block this adaptation through ERK and/or Src-mediated Cx43 phosphorylation. In preeclampsia such adapted function is already missing, but while elevated TNF is associated with this condition, particularly after 28 weeks (late PE), elevated circulating VEGF165 is not. Given PE is a long term condition emerging in the second half of pregnancy, and is often associated with added edema, we now compare the chronic effects of these two factors on the cell monolayer in order to establish if the breakdown of junctional adherens and tight junctional assemblies in which Cx43 resides could also explain loss of vasodilatory function. We report that while TNF can degrade monolayer integrity even in the 0.1–1 ng/ml physiologic range, VEGF up to 10 ng/ml does not. In addition, the progressive action of TNF is mediated through Src and ERK signaling to promote internalization and destruction of VE-Cadherin (VE-Cad) and ZO-1, as well as the expression and secretion of a variety of proteases. At least one protein degraded from the extracellular space is VE-Cad, resulting in release of a shed VE-Cad protein product, and consistent with monolayer breakdown being sensitive to both Src and MEK/ERK kinase inhibitors and the general protease inhibitor GM6001. We conclude that the greater association of TNF with ‘late’ PE is as much due to its longer term destabilizing effects on junctional assemblies as it is to acute closure of Cx43 channels themselves. New therapies aimed at stabilizing these junctional assemblies may help treat this hypertensive condition.

由于 Cx43 通讯的增加，子宫动脉内皮在怀孕期间经历了某种形式的功能适应，导致 Ca2+/IP3 交换增加以及更同步和持续的血管舒张剂产生。我们之前已经证明，急性暴露于生长因子和 TNF 可以通过 ERK 和/或 Src 介导的 Cx43 磷酸化来阻断这种适应。在先兆子痫中，这种适应功能已经缺失，但虽然 TNF 升高与这种情况相关，特别是在 28 周后（晚期 PE），但循环 VEGF165 升高却并非如此。鉴于 PE 是妊娠后半期出现的长期病症，并且通常与水肿增加有关，我们现在比较这两个因素对细胞单层的慢性影响，以确定连接粘附和紧密连接的破坏是否Cx43 所在的组装体也可以解释血管舒张功能的丧失。我们报告说，尽管 TNF 即使在 0.1-1 ng/ml 生理范围内也会降低单层完整性，但高达 10 ng/ml 的 VEGF 却不会。此外，TNF的渐进作用是通过Src和ERK信号传导介导的，促进VE-钙粘蛋白（VE-Cad）和ZO-1的内化和破坏，以及多种蛋白酶的表达和分泌。至少一种从细胞外空间降解的蛋白质是 VE-Cad，导致释放 VE-Cad 蛋白质产物的释放，并且与对 Src 和 MEK/ERK 激酶抑制剂以及通用蛋白酶抑制剂 GM6001 敏感的单层分解一致。我们得出的结论是，TNF 与“晚期”PE 的更大关联既是由于其对连接组件的长期不稳定影响，也是由于 Cx43 通道本身的急性关闭。旨在稳定这些连接组件的新疗法可能有助于治疗这种高血压病。