Post-transcriptional regulation of Kv11.1 (hERG) channel expression by alternative splicing and polyadenylation

KCNH2基因(人类乙醚-a-GO-GO相关基因，HERG)编码Kv11.1 K+通道， 在心脏传导快速激活的延迟整流钾电流(Ikr)。Kv11.1频道有助于 心脏动作电位的复极在遗传性和药物诱导性中都起着重要的作用 各种形式的长QT间期综合征。在KCNH2中已经发现了几种可供选择的经过加工的mRNA亚型。 其中两种亚型Kv11.1a和Kv11.1a-Uso在心脏中高水平表达。我们已经展示了 Kv11.1a和Kv11.1a-Uso表达是通过选择性剪接和聚腺苷酸化产生的 KCNH2前信使核糖核酸。Kv11.1a的全长亚型是通过内含子9的剪接和聚腺苷酸化而产生的 在外显子15的聚(A)位，而Kv11.1a-USO是通过内含子9的聚(A)位的多聚腺苷基化而产生的。 因为只有Kv11.1a亚型是有功能的，所以KCNH2前-mRNA的替代处理代表了一种 调节Kv11.1通道功能的转录后机制。更重要的是，破坏这一点 调节导致QT间期延长综合征。Kv11.1a和Kv11.1a-Uso的相对表达为 心脏处于发育调节状态。Kv11.1亚型调控机制的研究进展 表达方式还没有被完全理解。在目前的应用中，我们建议研究分子机制。 KCNH2前体基因的基础选择性剪接和多聚腺苷基化及其选择性剪接作用 和多聚腺苷酸化在心脏发育过程中对Kv11.1亚型表达的调节以及在遗传性和遗传性 药物性QT间期延长综合征。具体目标是：目标1：确定顺式作用元件 KCNH2前体mRNA的选择性剪接和多聚腺苷酸化及其恢复表达的策略 功能性Kv11.1a亚型的突变被长QT综合征相关突变破坏。目标2：学习 RNA结合蛋白CELF1、CELF2和SF3B1对Kv11.1亚型表达的调控作用目标3： 人源化敲击中Kv11.1亚型表达的发育调控机制研究 老鼠模型。目的4：研究新型抗癌药物SF3B1抑制剂对Kv11.1亚型的影响 表情。这些研究的结果将提供有关分子机制的详细信息。 KCNH2前体mRNA的选择性剪接和多聚腺苷酸化以及这一过程在正常和 疾病状况。阐明这些机制将加强我们对转录后转录的理解。 Kv11.1通道表达的调控及其在评价致心律失常中的重要意义 在药物开发过程中的责任。

The KCNH2 gene (human ether-a-go-go-related gene, hERG) encodes the Kv11.1 K+ channel that conducts the rapidly activating delayed rectifier K+ current (IKr) in the heart. The Kv11.1 channel contributes to the repolarization of cardiac action potentials and plays an important role in both inherited and drug-induced forms of long QT syndrome. Several alternatively processed mRNA isoforms have been identified in KCNH2. Two of these isoforms, Kv11.1a and Kv11.1a-USO, are expressed at high levels in the heart. We have shown that expression of Kv11.1a and Kv11.1a-USO are generated by alternative splicing and polyadenylation of KCNH2 pre-mRNA. The full-length Kv11.1a isoform is produced by the splicing of intron 9 and polyadenylation at a poly(A) site in exon 15, whereas Kv11.1a-USO is generated by polyadenylation at a poly(A) site in intron 9. Because only the Kv11.1a isoform is functional, the alternative processing of KCNH2 pre-mRNA represents a post-transcriptional mechanism that regulates Kv11.1 channel function. More importantly, disruption of this regulation leads to long QT syndrome. The relative expression of Kv11.1a and Kv11.1a-USO is developmentally regulated in the heart. The mechanisms underlying the regulation of Kv11.1 isoform expression are not fully understood. In the present application, we propose to study the molecular mechanisms underlying alternative splicing and polyadenylation of KCNH2 pre-mRNA and the role of alternative splicing and polyadenylation in regulation of Kv11.1 isoform expression during heart development and in inherited and drug-induced long QT syndrome. The specific aims are: Aim 1: To identify the cis-acting elements that regulate alternative splicing and polyadenylation of KCNH2 pre-mRNA and to develop strategies to restore expression of the functional Kv11.1a isoform disrupted by a long QT syndrome-associated mutation. Aim 2: To study effects of RNA binding proteins CELF1, CELF2 and SF3B1 on regulation of Kv11.1 isoform expression. Aim 3: To study mechanisms of developmental regulation of Kv11.1 isoform expression in a humanized knock-in mouse model. Aim 4: To study effects of SF3B1 inhibitors, a new class of anticancer drugs, on Kv11.1 isoform expression. The results from these studies will provide detailed information about the molecular mechanisms of alternative splicing and polyadenylation of KCNH2 pre-mRNA and how this process is regulated in normal and disease conditions. Elucidating these mechanisms will strengthen our understanding of post-transcriptional regulation of Kv11.1 channel expression and have important implications in the assessment of arrhythmogenic liability during drug development.