Department of Anatomy & Neurobiology, University of California, Irvine, USA.
Thromb Res. 2012 Jun;129(6):750-3. doi: 10.1016/j.thromres.2011.12.008. Epub 2012 Jan 13.
Factors regulating brain tissue plasminogen activator (tPA) are pertinent for stroke. Recent observations have suggested a role for the phosphodiesterase-4 (PDE4) pathway in stroke pathogenesis, via an uncertain mechanism. We studied PDE4 regulation of tPA expression by human brain microvascular endothelial cells in a variety of conditions, including an in vitro model of ischemia.
We analyzed tPA antigen and mRNA of human brain microvascular endothelial cells (HBECs) during normoxia and oxygen-glucose deprivation (OGD) following inhibition of PDE4 and PDE4D, using HBEC monocultures and co-cultures with astrocytes and pericytes, and analyzed relevant signal transduction pathways.
PDE4 inhibitor rolipram enhanced OGD effects on endothelial tPA release in endothelial monocultures and co-cultures with astrocytes; there was a 54±10% (p<0.001) reduction of tPA release in astrocyte-endothelial co-cultures under OGD. PDE4D siRNA reduced endothelial tPA mRNA to 40-55% of control (p<0.05). Use of Epac inducer mimicked, while use of Epac siRNA inhibited, these effects.
Inhibition of PDE4 and PDE4D reduced expression of tPA by HBEC via Epac pathway.
调节脑组织纤溶酶原激活物（tPA）的因素与中风有关。最近的观察结果表明，磷酸二酯酶-4（PDE4）途径通过一种不确定的机制在中风发病机制中起作用。我们研究了在各种条件下，包括体外缺血模型中，人脑血管内皮细胞（HBEC）中 PDE4 对 tPA 表达的调节作用。
我们分析了在 HBEC 单核培养物和与星形胶质细胞和周细胞的共培养物中，正常氧和氧葡萄糖剥夺（OGD）期间 HBEC 中 tPA 抗原和 mRNA 的表达，在抑制 PDE4 和 PDE4D 后，分析了相关的信号转导途径。
PDE4 抑制剂罗利普兰增强了内皮单核培养物和与星形胶质细胞共培养物中 OGD 对内皮细胞 tPA 释放的影响；在 OGD 下，星形胶质细胞-内皮共培养物中 tPA 释放减少了 54±10%（p<0.001）。PDE4D siRNA 将内皮 tPA mRNA 减少至对照的 40-55%（p<0.05）。Epac 诱导剂的使用模拟了这些作用，而 Epac siRNA 的使用则抑制了这些作用。
通过 Epac 途径，HBEC 中 PDE4 和 PDE4D 的抑制降低了 tPA 的表达。
