Removal of FKBP12.6 Does Not Alter the Conductance and Activation of the Cardiac Ryanodine Receptor or the Susceptibility to Stress-induced Ventricular Arrhythmias*
Removal of FKBP12.6 Does Not Alter the Conductance and Activation of the Cardiac Ryanodine Receptor or the Susceptibility to Stress-induced Ventricular Arrhythmias*
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DOI：
10.1074/jbc.m707423200
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发表时间：
2007-11
影响因子：
4.8
通讯作者：
Jianmin Xiao;Xixi Tian;P. Jones;Jeff Bolstad;Huihui Kong;Ruiwu Wang;Lin Zhang;H. Duff;A. Gillis;S. Fleischer;M. Kotlikoff;J. Copello;Wayne S. R. Chen
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文献类型：
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作者：
Jianmin Xiao;Xixi Tian;P. Jones;Jeff Bolstad;Huihui Kong;Ruiwu Wang;Lin Zhang;H. Duff;A. Gillis;S. Fleischer;M. Kotlikoff;J. Copello;Wayne S. R. Chen
12.6 kDa FK 506结合蛋白（FKBP12.6）被认为是心脏ryanodine受体（RyR 2）的关键调节因子，但其在RyR 2功能中的确切作用是复杂和有争议的。在本研究中，我们研究了去除FKBP 12.6对RyR 2通道特性、自发性Ca 2+释放倾向和室性心律失常发生率的影响。脂质双层中的单通道记录显示，FK 506处理与或不与FKBP12.6或天然犬RyR 2共表达的重组RyR 2不会诱导长寿命亚电导状态。[3 H]Ryanodine结合研究显示，与或不与FKBP 12.6共表达或与或不与FK 506处理不会改变RyR 2对Ca 2+或咖啡因激活的敏感性。此外，单细胞Ca 2+成像分析表明，共表达RyR 2和FKBP12.6或单独表达RyR 2的HEK 293细胞显示出相同的自发Ca 2+释放或储存超负荷诱导的Ca 2+释放（SOICR）倾向。FK 506在有或没有FKBP12.6的情况下增加表达RyR 2的HEK 293细胞中SOICR的振幅并降低其频率，表明FK 506对SOICR的作用不依赖于FKBP12.6。与重组RyR 2一样，来自FKBP12.6缺失小鼠的单个RyR 2通道的电导和配体门控特性与单个野生型通道的电导和配体门控特性无法区分。此外，FKBP12.6-null小鼠没有表现出对应激诱导的室性心律失常的敏感性增强，与以前的报道相反。总的来说，我们的研究结果表明，FKBP 12.6的损失没有显着影响的传导和激活RyR 2或自发的Ca 2+释放和应激诱导的室性心律失常的倾向。
The 12.6-kDa FK506-binding protein (FKBP12.6) is considered to be a key regulator of the cardiac ryanodine receptor (RyR2), but its precise role in RyR2 function is complex and controversial. In the present study we investigated the impact of FKBP12.6 removal on the properties of the RyR2 channel and the propensity for spontaneous Ca2+ release and the occurrence of ventricular arrhythmias. Single channel recordings in lipid bilayers showed that FK506 treatment of recombinant RyR2 co-expressed with or without FKBP12.6 or native canine RyR2 did not induce long-lived subconductance states. [3H]Ryanodine binding studies revealed that coexpression with or without FKBP12.6 or treatment with or without FK506 did not alter the sensitivity of RyR2 to activation by Ca2+ or caffeine. Furthermore, single cell Ca2+ imaging analyses demonstrated that HEK293 cells co-expressing RyR2 and FKBP12.6 or expressing RyR2 alone displayed the same propensity for spontaneous Ca2+ release or store overload-induced Ca2+ release (SOICR). FK506 increased the amplitude and decreased the frequency of SOICR in HEK293 cells expressing RyR2 with or without FKBP12.6, indicating that the action of FK506 on SOICR is independent of FKBP12.6. As with recombinant RyR2, the conductance and ligand-gating properties of single RyR2 channels from FKBP12.6-null mice were indistinguishable from those of single wild type channels. Moreover, FKBP12.6-null mice did not exhibit enhanced susceptibility to stress-induced ventricular arrhythmias, in contrast to previous reports. Collectively, our results demonstrate that the loss of FKBP12.6 has no significant effect on the conduction and activation of RyR2 or the propensity for spontaneous Ca2+ release and stress-induced ventricular arrhythmias.