RNA Toxicity and Cardiac Pathology

项目摘要： 强直性肌营养不良（DM 1）是成人和儿童中最常见的肌营养不良形式，是常染色体显性遗传。 由DM蛋白激酶（DMPK）基因中CTG重复扩增引起的显性遗传疾病， 突变RNA的核保留和随后的RNA毒性。心脏是人体的主要器官之一 在DM 1中受影响。高达75%的成人DM 1病例存在心脏传导问题， 由于心律失常是DM 1中最常见的死亡原因之一。不幸的是， DM 1的心脏表现尚不清楚。糖尿病1型心脏病的临床重点一直是 心律失常和传导异常。值得注意的是，DM 1中心脏缺陷的病理学在历史上一直是 与间质纤维化、脂肪浸润和心脏传导组织纤维化相关。我们报道 第一个可诱导的RNA毒性和心脏传导缺陷的小鼠模型，并证明了 通过沉默有毒RNA的产生来逆转DM 1表型。最近使用DM 200小鼠模型， 我们第一次展示了反义寡核苷酸（ASO）治疗DM 1心脏病的潜力。 我们还发现了与心脏RNA毒性相关的纤维化变化的证据。近十年来 新的心脏磁共振成像研究的出现，导致了对心脏磁共振成像的证据和越来越多的兴趣， DM 1中的纤维化及其在DM 1临床病理学中的作用。我们建议使用DM 200小鼠模型作为 在临床前模型中开发和研究这些想法和概念的工具，并试图理解 心脏纤维脂肪形成变化的细胞和分子驱动因素。我们将通过三个 独立但互补的目标。首先，我们将开发和评估心脏MRI作为RNA的生物标志物 心脏的毒性。第二，我们将确定心脏PDGFRA+ve细胞在心肌/脂肪形成中的作用。 心脏对RNA毒性的病理反应。第三，根据TGFβ增加的初步证据， 心脏，我们将描述TGFβs在心脏RNA毒性中的作用，并研究治疗反应。 涉及靶向纤维化和TGFβ（包括针对TGFβ2和TGFβ3的同种型特异性抗体）的疗法。 重要的是，我们将在治疗试验中验证CMR方案和参数，使用： 靶向毒性RNA的ASO和B）靶向纤维化和TGFβ的疗法。我们的目标是了解 DM 1中与RNA毒性相关的心脏病理学驱动因素，并评估和确定 心脏MRI作为监测疾病进展和治疗反应的工具的实用性。

Project Summary: Myotonic dystrophy (DM1), the most common form of muscular dystrophy in adults and children, is an autosomal dominant genetic disorder caused by an expanded CTG repeat in the DM protein kinase (DMPK) gene that leads to nuclear retention of the mutant RNA and subsequent RNA toxicity. The heart is one of the primary organs affected in DM1. Cardiac conduction problems are present in up to 75% of adult DM1 cases, and sudden death due to cardiac arrhythmias is one of the most common causes of death in DM1. Unfortunately, the pathogenesis of cardiac manifestations in DM1 is not well understood. Clinical focus for cardiac disease in DM1 has been on arrhythmias and conduction abnormalities. Of note, the pathology of cardiac defects in DM1 has been historically associated with interstitial fibrosis, and fatty infiltration and fibrosis of cardiac conduction tissues. We reported the first inducible mouse model of RNA toxicity and cardiac conduction defects and demonstrated the potential for reversibility of DM1 phenotypes by silencing toxic RNA production. Recently using the DM200 mouse model, we showed for the first time, the potential for antisense oligonucleotides (ASOs) to treat cardiac disease in DM1. We also found evidence for fibrotic changes associated with RNA toxicity in the heart. In the past decade, the advent of new cardiac MRI studies has led to evidence of and an increased interest in understanding cardiac fibrosis in DM1 and its role in the clinical pathology of DM1. We propose to use the DM200 mouse model as a tool for developing and investigating these ideas and concepts in a pre-clinical model and to try to understand the cellular and molecular drivers of fibro-adipogenic changes in the heart. We will do this through three independent but complementary aims. First, we will develop and evaluate cardiac MRI as a biomarker for RNA toxicity in the heart. Second, we will determine the role of cardiac PDGFRA+ve cells in fibro/adipogenic pathologic responses to RNA toxicity in the heart. Third, based on preliminary evidence of increased TGFβ in the heart, we will characterize the role of TGFβs in RNA toxicity in the heart, and study the therapeutic response to therapies targeting fibrosis and TGFβ (including isoform specific antibodies against TGFβ2 and TGFβ3). Importantly, we will validate the CMR protocols and parameters in therapeutic trials using: a) next generation ASOs that target the toxic RNA and b) the therapies targeting fibrosis and TGFβs. Our goals are to understand the drivers of cardiac pathology associated with RNA toxicity in DM1, and to evaluate and establish the potential utility of cardiac MRI as a tool to monitor disease progression and response to therapy.