Na+ channel mRNA splicing in heart failure

心力衰竭中的 Na 通道 mRNA 剪接

• 批准号: 8154997
• 负责人: SAMUEL C DUDLEY
• 金额: $ 39.75万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-15 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8154997
• 关键词: A Mouse; Adjuvant Therapy; Affect; Alleles; Alternative Splicing; American; Amiodarone; Angiotensin II; Arrhythmia; Binding; Blood Tests; Cardiac; Clinical; Clinical Trials; Complex; Data; Defibrillators; Dominant-Negative Mutation; Down-Regulation; Embryo; Endoplasmic Reticulum; Exons; Figs - dietary; Genes; Half-Life; Heart Diseases; Heart failure; Human; Hypoxia; Implant; Lead; Length; Leukocytes; Measures; Messenger RNA; Morbidity - disease rate; Myocardial Infarction; Outcome; Pathologic; Pathway interactions; Pharmaceutical Preparations; Phase; Physiological; Prevention strategy; Process; Proteins; RNA Splicing; Regulation; Reporting; Research; Risk; Sampling; Severities; Shock; Signal Transduction; Sodium Channel; Splicing Regulation Pathway; Sudden Death; Systolic heart failure; Time; Tissues; Titrations; Transcript; Translations; Variant; Ventricular; Ventricular Premature Complexes; Ventricular Tachycardia; Work; base; drug efficacy; mRNA Expression; mortality; mouse model; novel; open label; response

DESCRIPTION (provided by applicant): Despite the extensive research and novel treatments, human systolic heart failure (HF) remains a substantial clinical problem affecting millions of Americans and HF associated arrhythmia still remains a cause of the high morbidity and mortality. Recently, three SCN5a cardiac Na+ channel mRNA alternative splicing variants were found to be upregulated in human HF tissue. These splicing variants resulted from splicing at cryptic splice sequences in the terminal exon of SCN5a (i.e., exon 28) and encoded cardiac Na+ channels truncated before the pore forming segment of domain IV. Variant levels reached greater that >50% of the total SCN5a mRNA. As expected, these variants did not form functional channels. Moreover, the presence of the variants caused reduced abundance of the full-length SCN5a mRNA without alteration of total SCN5a mRNA. This application proposes to establish the mechanism whereby the abnormal splicing occurs in HF and how the presence of truncated Na+ channel variants causes a dominant negative downregulation of the full-length channel mRNA. Preliminary data suggest hypoxia and angiotensin II (AngII) can signal pathological SCN5a splicing regulation by inducing expression of the mRNA splicing factor, CROP/hLuc7A, and its co-factor RBM25, which alter SCN5a splicing regulation by interacting with one or more RBM25 binding sequences CGGGC(A) in SCN5a exon 28, the exon where abnormal splicing of SCN5a occurs. Furthermore, data show that truncated Na+ channels accumulate in endoplasmic reticulum (ER) and initiate the unfolded protein response (UPR) pathway, causing reduced Na+ channel translation and a shortened half-life of the full-length SCN5a transcript. Hypothesis. Based on the above, we hypothesized that the hLuc7A/RBM25 complex contributes to abnormal Na+ channel mRNA splicing and that the UPR contributes to the dominant negative effect the abnormally spliced transcripts have on the Na+ channel. Specific Objectives. Specific aim 1: To establish whether the hLuc7A/RBM25 splicing regulation pathway is involved in the mechanism to increase SCN5a mRNA variant expression. Specific aim 2: To determine to what extent the three major pathways in the unfolded protein response (UPR) are responsible for the reduction in functional Na+ channels. Specific aim 3: To demonstrate the relationship of hLuc7A/RBM25 regulation, the unfolded protein response (UPR) activation, Na+ channel mRNA variants, and Na+ channel measures in human heart failure samples. PUBLIC HEALTH RELEVANCE: The cause of sudden death in heart failure is unknown. This application will explore one potential cause, abnormal sodium channel processing, establishing the mechanism and possible elucidating prevention strategies. Moreover, if white cells show similar abnormalities, this work may lead to a blood test to predict sudden death risk in heart failure.

描述（由申请人提供）：尽管进行了广泛的研究和新的治疗方法，但人类收缩性心力衰竭（HF）仍然是一个实质性的临床问题，影响了数百万美国人和HF相关的心律不齐仍然是高发病率和死亡率的原因。最近，发现在人HF组织中发现了三个SCN5A心脏Na+通道mRNA替代剪接变体。这些剪接变体是由SCN5A末端外显子（即外显子28）中的隐秘剪接序列进行的剪接以及编码心脏Na+通道在域IV的孔段段之前截断的。变异水平达到了总SCN5A mRNA的50％。正如预期的那样，这些变体未形成功能通道。此外，这些变体的存在导致全长SCN5A mRNA的丰度降低，而不会改变总SCN5A mRNA。该应用建议建立一种机制，使异常剪接发生在HF中，以及截短的Na+通道变体的存在如何导致全长通道mRNA的主要负下调。初步数据表明缺氧和血管紧张素II（ANGII）可以通过诱导MRNA剪接因子的表达来表达病理SCN5A剪接调节调节，作物/HLUC7A及其辅助因子RBM25，从而改变SCN5A旋转调节，通过与一个或多个rbM25结合序列相互作用CGGG（scgg）cgggc（scgggc）（scgggc）（scgggc）（scgggc）ace in abn scgg cggg（a）发生SCN5A的剪接。此外，数据表明，截短的Na+通道在内质网（ER）中积累，并启动展开的蛋白质反应（UPR）途径，从而导致Na+通道翻译减少和全长SCN5A转录的半衰期缩短。假设。基于上述情况，我们假设HLUC7A/RBM25复合物有助于异常Na+通道mRNA剪接，并且UPR有助于异常剪接的转录物对Na+通道的主要负效应。特定目标。具体目标1：确定HLUC7A/RBM25剪接调节途径是否参与增加SCN5A mRNA变异表达的机制。具体目标2：确定未折叠蛋白反应（UPR）中的三个主要途径在多大程度上导致功能性Na+通道的降低。具体目的3：为了证明HLUC7A/RBM25调节的关系，未展开的蛋白质反应（UPR）激活，Na+通道mRNA变异和人体心力衰竭样品中的Na+通道测量。 公共卫生相关性：心力衰竭突然死亡的原因尚不清楚。该应用将探讨一个潜在的原因，即钠通道的异常，建立机制和可能阐明预防策略。此外，如果白细胞表现出相似的异常，这项工作可能会导致血液检查以预测心力衰竭的猝死风险。