Tubulin polymerization disrupts cardiac β-adrenergic regulation of late INa
Tubulin polymerization disrupts cardiac β-adrenergic regulation of late INa
复制标题
DOI：
10.1093/cvr/cvu120
复制
发表时间：
2014-07-01
影响因子：
10.8
通讯作者：
Maier, Lars S.
中科院分区：
文献类型：
--
作者：
Dybkova, Nataliya;Wagner, Stefan;Maier, Lars S.
聚合微管的抗癌药物紫杉醇 (TXL) 与心律失常和窦房结功能障碍有关。 TXL 可以改变 Na 通道 (Na(V)1.5) 和 Na 电流 (I-Na) 的膜表达，但其机制尚不清楚。钙/钙调蛋白依赖性蛋白激酶 II (CaMKII) 可通过 β-肾上腺素能刺激激活并调节 I-Na 门控。我们测试了 TXL 是否会干扰异丙肾上腺素 (ISO) 诱导的 CaMKII 激活和随后的 I-Na 调节。在野生型小鼠肌细胞中，添加 ISO (1 A mu mol/L) 会导致 CaMKII 自磷酸化增加（蛋白质印迹）。经过TXL（100 A mumol/L，1.5 h）预处理后，这种增加完全消失。在人胚胎肾细胞中进一步研究了该机制。 TXL 抑制 ISO 诱导的 β-arrestin 易位。有趣的是，使用小干扰 RNA 敲低 β-arrestin2 表达和抑制 cAMP (Epac) 直接激活的交换蛋白都可以阻断 ISO 诱导的 CaMKII 自磷酸化，与 TXL 类似。然而，cAMP 的生成没有改变（Epac1-camps）。使用膜片钳技术在分离的心肌细胞中测量 CaMKII 依赖性 Na 通道功能。与 TXL 预孵育后，ISO 刺激未能诱导 CaMKII 依赖性的晚期 I-Na 和 Na 通道失活增强（稳态激活中的负电压变化和增强的中间失活）。与此一致的是，TXL 还抑制 ISO 诱导的 CaMKII 特异性 Na 通道磷酸化（Na(V)1.5 的丝氨酸 571）。与 TXL 预孵育会破坏 ISO 依赖性 CaMKII 激活和随后的 Na 通道调节。这对于接受 TXL 治疗的患者可能很重要，但也与 CaMKII 表达增加和 β-肾上腺素能刺激增强（如心力衰竭）的情况相关。
The anticancer drug paclitaxel (TXL) that polymerizes microtubules is associated with arrhythmias and sinus node dysfunction. TXL can alter membrane expression of Na channels (Na(V)1.5) and Na current (I-Na), but the mechanisms are unknown. Calcium/calmodulin-dependent protein kinase II (CaMKII) can be activated by beta-adrenergic stimulation and regulates I-Na gating. We tested whether TXL interferes with isoproterenol (ISO)-induced activation of CaMKII and consequent I-Na regulation.In wild-type mouse myocytes, the addition of ISO (1 A mu mol/L) resulted in increased CaMKII auto-phosphorylation (western blotting). This increase was completely abolished after pre-treatment with TXL (100 A mu mol/L, 1.5 h). The mechanism was further investigated in human embryonic kidney cells. TXL inhibited the ISO-induced beta-arrestin translocation. Interestingly, both knockdown of beta-arrestin2 expression using small interfering RNA and inhibition of exchange protein directly activated by cAMP (Epac) blocked the ISO-induced CaMKII auto-phosphorylation similar to TXL. The generation of cAMP, however, was unaltered (Epac1-camps). CaMKII-dependent Na channel function was measured using patch-clamp technique in isolated cardiomyoctes. ISO stimulation failed to induce CaMKII-dependent enhancement of late I-Na and Na channel inactivation (negative voltage shift in steady-state activation and enhanced intermediate inactivation) after pre-incubation with TXL. Consistent with this, TXL also inhibited ISO-induced CaMKII-specific Na channel phosphorylation (at serine 571 of Na(V)1.5).Pre-incubation with TXL disrupts the ISO-dependent CaMKII activation and consequent Na channel regulation. This may be important for patients receiving TXL treatments, but also relevant for conditions of increased CaMKII expression and enhanced beta-adrenergic stimulation like in heart failure.