Epac/Rap1 pathway regulates microvascular hyperpermeability induced by PAF in rat mesentery
Epac/Rap1 pathway regulates microvascular hyperpermeability induced by PAF in rat mesentery
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DOI：
10.1152/ajpheart.00937.2007
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发表时间：
2008-03-01
影响因子：
4.8
通讯作者：
Curry, F. E.
中科院分区：
文献类型：
--
作者：
Adamson, R. H.;Ly, J. C.;Curry, F. E.
培养的内皮细胞单层实验表明，细胞内 cAMP 的增加可通过蛋白激酶 A (PKA) 依赖性和非依赖性途径强烈抑制急性通透性反应。完整哺乳动物微血管中 PKA 独立通路对 cAMP 抗炎机制的贡献尚未得到系统研究。我们评估了 cAMP (Epac) 激活的交换蛋白的 cAMP 依赖性激活的作用，cAMP (Epac) 是小 GTPase Rap1 的鸟嘌呤核苷酸交换因子，在暴露于血小板激活因子 (PAF) 的大鼠静脉微血管中的作用。 cAMP 类似物 8-pCPT-2'-O-甲基-cAMP (O-Me-cAMP) 可刺激 Epac/Rap1 通路，但对 PKA 没有影响，可显着减弱 PAF 微血管通透性的增加（通过水力电导率 (L-p) 测量）。我们还证明，PAF 诱导血管内皮 (VE)-钙粘蛋白的重排，在其他连续的外周免疫荧光标记中表现为大量横向尖峰和频繁的短暂中断。 O-Me-cAMP 预处理完全阻止了 PAF 诱导的 VE-钙粘蛋白重排。我们得出的结论是，Epac/Rap1 通路稳定细胞间粘附的作用是 cAMP 减弱血管通透性急剧增加的活性的重要组成部分。我们的结果表明，PAF 等急性炎症因子导致完整微血管的通透性增加，是 Epac/Rap1 通路调节细胞间粘附的有效性降低的结果。
Experiments in cultured endothelial cell monolayers demonstrate that increased intracellular cAMP strongly inhibits the acute permeability responses by both protein kinase A (PKA)-dependent and -independent pathways. The contribution of the PKA-independent pathways to the anti-inflammatory mechanisms of cAMP in intact mammalian microvessels has not been systematically investigated. We evaluated the role of the cAMP-dependent activation of the exchange protein activated by cAMP (Epac), a guanine nucleotide exchange factor for the small GTPase Rap1, in rat venular microvessels exposed to the platelet-activating factor (PAF). The cAMP analog 8-pCPT-2'-O-methyl-cAMP (O-Me-cAMP), which stimulates the Epac/Rap1 pathway but has no effect on PKA, significantly attenuated the PAF increase in microvessel permeability as measured by hydraulic conductivity (L-p). We also demonstrated that PAF induced a rearrangement of vascular endothelial (VE)-cadherin seen as numerous lateral spikes and frequent short breaks in the otherwise continuous peripheral immunofluorescent label. Pretreatment with O-Me-cAMP completely prevented the PAF-induced rearrangement of VE-cadherin. We conclude that the action of the Epac/Rap1 pathway to stabilize cell-cell adhesion is a significant component of the activity of cAMP to attenuate an acute increase in vascular permeability. Our results indicate that increased permeability in intact microvessels by acute inflammatory agents such as PAF is the result of the decreased effectiveness of the Epac/Rap1 pathway modulation of cell-cell adhesion.