A novel human R25C-phospholamban mutation is associated with super-inhibition of calcium cycling and ventricular arrhythmia
A novel human R25C-phospholamban mutation is associated with super-inhibition of calcium cycling and ventricular arrhythmia
复制标题
DOI：
10.1093/cvr/cvv127
复制
发表时间：
2015-07-01
影响因子：
10.8
通讯作者：
Kranias, Evangelia G.
中科院分区：
文献类型：
--
作者：
Liu, Guan-Sheng;Morales, Ana;Kranias, Evangelia G.
肌浆网（SR）钙循环抑制是人类和实验性心力衰竭的普遍特征，可能与关键钙处理蛋白的遗传改变有关。在这项研究中，我们确定了一种新的PLN突变（R25 C）在扩张型心肌病（DCM），并探讨其在心肌细胞Ca 2+处理和contractility.Methods和结果外显子组测序的功能意义，确定了一个C73 T取代在编码区的PLN在一个家庭与DCM。四个杂合子家族成员有植入式心脏起搏器，三个发生了明显的室性心律失常。与WT-PLN相比，R25 C-PLN在成年大鼠心肌细胞中的过表达显著抑制SR Ca 2 +-ATP酶（SERCA 2a）的Ca 2+亲和力，导致SR Ca 2+含量降低，Ca 2+瞬变和收缩功能受损。这些抑制作用与R25 C-PLN与SERCA 2的增强的相互作用相关，这被PKA磷酸化阻止。因此，异丙肾上腺素刺激缓解了R25 C-PLN在心肌细胞中的抑制作用。然而，R25 C-PLN也引起Ca 2+火花和波的频率增加，以及应力诱导的后收缩。结论人R25 C-PLN可抑制SERCA 2a和Ca 2+转运，增加肌浆网Ca 2+渗漏，促进应激条件下的细胞增殖。这是第一个机制证据，表明PLN抑制增加可能影响SR Ca 2+摄取和Ca 2+释放活性，并表明人R25 C-PLN可能是DCM携带者室性心律失常风险增加的预后因素。
Aims Depressed sarcoplasmic reticulum (SR) Ca2+ cycling, a universal characteristic of human and experimental heart failure, may be associated with genetic alterations in key Ca2+-handling proteins. In this study, we identified a novel PLN mutation (R25C) in dilated cardiomyopathy (DCM) and investigated its functional significance in cardiomyocyte Ca2+-handling and contractility.Methods and results Exome sequencing identified a C73T substitution in the coding region of PLN in a family with DCM. The four heterozygous family members had implantable cardiac defibrillators, and three developed prominent ventricular arrhythmias. Overexpression of R25C-PLN in adult rat cardiomyocytes significantly suppressed the Ca2+ affinity of SR Ca2+-ATPase (SERCA2a), resulting in decreased SR Ca2+ content, Ca2+ transients, and impaired contractile function, compared with WT-PLN. These inhibitory effects were associated with enhanced interaction of R25C-PLN with SERCA2, which was prevented by PKA phosphorylation. Accordingly, isoproterenol stimulation relieved the depressive effects of R25C-PLN in cardiomyocytes. However, R25C-PLN also elicited increases in the frequency of Ca2+ sparks and waves as well as stress-induced aftercontractions. This was accompanied by increased Ca2+/calmodulin-dependent protein kinase II activity and hyper-phosphorylation of RyR2 at serine 2814.Conclusion The findings demonstrate that human R25C-PLN is associated with super-inhibition of SERCA2a and Ca2+ transport as well as increased SR Ca2+ leak, promoting arrhythmogenesis under stress conditions. This is the first mechanistic evidence that increased PLN inhibition may impact both SR Ca2+ uptake and Ca2+ release activities and suggests that the human R25C-PLN may be a prognostic factor for increased ventricular arrhythmia risk in DCM carriers.