Pak1 is required to maintain ventricular Ca²⁺ homeostasis and electrophysiological stability through SERCA2a regulation in mice.
Pak1 is required to maintain ventricular Ca²⁺ homeostasis and electrophysiological stability through SERCA2a regulation in mice.
复制标题
在小鼠中，Pak1 需要通过 SERCA2a 调节来维持心室 Ca2+ 稳态和电生理稳定性。
DOI：
10.1161/circep.113.001198
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发表时间：
2014-10
期刊：
影响因子：
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通讯作者：
Lei M
中科院分区：
文献类型：
--
作者：
Wang Y;Tsui H;Ke Y;Shi Y;Li Y;Davies L;Cartwright EJ;Venetucci L;Zhang H;Terrar DA;Huang CL;Solaro RJ;Wang X;Lei M
肌浆网(SR)钙摄取受损是心力衰竭(HF)及其伴发室性心律失常的特征，SERCA2a表达或活性降低导致SR钙摄取减少。最近对这些疾病的基因治疗的尝试探索了增强SERCA2a表达和/或活性的策略，作为HF管理的新方法。在此，我们探讨了在正常生理和急、慢性β-肾上腺素能应激条件下，PAK1在维持心室肌钙稳态和电生理稳定性中的作用。在异丙肾上腺素诱导的急性或慢性β肾上腺素能应激导致肥大的过程中，具有心肌细胞特异性Pak1缺失(Pak1cko)而不是对照组(Pak1f/f)的小鼠表现出高发生率的室性心律失常和电生理不稳定。分离的pak1cko心肌细胞相应地表现出细胞内钙稳态的异常。Pak1cko心脏表现为SERCA2a功能受损，SERCA2a基因和蛋白表达下调。对转录调控改变机制的进一步探索表明，在苯肾上腺素应激下，暴露于控制Ad-shC2病毒感染的新生大鼠心肌细胞(NRCM)中SERCA2a蛋白和mRNA水平增加。在Ad-shPak1感染的NRCM中，这种表达被Pak1基因敲除而被取消，而被活性Pak1的结构性过表达(Ad-CAPak1)所增加。然后，我们发现了血清反应因子(SRF)的激活，这是一种转录因子，众所周知，它在PAC1依赖的SERCA2a调节中对心脏生成基因的调节起着至关重要的作用。这些发现表明，Pak1是维持心肌细胞内钙稳态和电生理稳定性所必需的，并且通过转录机制提示Pak1是一种新的心脏SERCA2a调节因子。
Impaired sarcoplasmic reticular (SR) Ca2+ uptake resulting from decreased SR Ca2+-ATPase type 2a (SERCA2a) expression or activity is characteristic of heart failure (HF) with its associated ventricular arrhythmias. Recent attempts at gene therapy of these conditions explored strategies enhancing SERCA2a expression and/or activity as novel approaches to HF management. We here explore the role of Pak1 in maintaining ventricular Ca2+ homeostasis and electrophysiological stability under both normal physiological, and acute and chronic β-adrenergic stress conditions. Mice with a cardiomyocyte-specific Pak1 deletion (Pak1cko), but not controls (Pak1f/f), showed high incidences of ventricular arrhythmias and electrophysiological instability during either acute β-adrenergic or chronic β-adrenergic stress leading to hypertrophy, induced by isoproterenol. Isolated Pak1cko ventricular myocytes correspondingly showed aberrant cellular Ca2+ homeostasis. Pak1cko hearts showed an associated impairment of SERCA2a function and down-regulation of SERCA2a mRNA and protein expression. Further explorations of the mechanisms underlying the altered transcriptional regulation demonstrated that exposure to control Ad-shC2 virus infection increased SERCA2a protein and mRNA levels following phenylephrine stress in cultured neonatal rat cardiomyocytes (NRCMs). This was abolished by the Pak1-knockdown in Ad-shPak1-infected NRCMs and increased by constitutive over-expression of active Pak1 (Ad-CAPak1). We then implicated activation of serum response factor (SRF), a transcriptional factor well-known for its vital role in regulation of cardiogenesis genes in the Pak1-dependent regulation of SERCA2a. These findings indicate that Pak1 is required to maintain ventricular Ca2+ homeostasis and electrophysiological stability and implicate Pak1 as a novel regulator of cardiac SERCA2a through a transcriptional mechanism.