Genetic Studies of Sarcomere-based Cardiac Diseases

扩张型心肌病（DCM）是一种具有遗传异质性和可变表型的疾病。 肌联蛋白截短变体（TTNtvs）-无义、移码和必需剪接位点，已被发现是 扩张型心肌病最常见的遗传因素然而，TTNtv也存在于参考人群中， 目前尚不清楚为什么致病性TTNtv主要存在于编码A带结构域的外显子中， 其他外显子中的TTNtv，如影响N-末端Z-盘结构域的那些，可能是良性的。此外，委员会认为， 具有相同TTN突变的患者可以表现出高度可变的疾病表型，大概是因为 个人基因组中不同的遗传背景。为了解决基于TTN的这两个瓶颈， DCM，我们利用了高效的斑马鱼遗传学。为了填补等位基因异质性的第一个知识空白，我们 利用基因组编辑技术，产生了10多个影响Z盘或A带的ttntv 斑马鱼的外显子为了填补可变表型的第二个知识空白，我们建立了一个新的 诱变筛选为基础的战略，并成功地确定了4个遗传修饰剂的DOX诱导 心肌病我们的前提是，这些修饰剂和相关疗法中的一些用于DOX诱导的 心肌病也可能适用于基于TTN的DCM。我们建议进行全面的 这些TTNTV和候选遗传修饰剂的遗传研究，以阐明机制并寻求 基于TTNtv的DCM的治疗策略。在我们的具体目标1中，我们的目标是定义表型性状， 基于ttn的DCM，并辨别毒性肽，外显子使用和cronos假设的等位基因异质性， 基于ttn的DCM。在我们的具体目标2中，我们将阐明短ttn-novex 3同种型的新功能， 检验影响ttn-novex 3同种型的N-末端ttntvs是心肌病修饰剂的假设。在 我们的具体目标3，我们将确定是否为DOX诱导的心肌病的4个修饰突变体， 也对基于ttn的DCM发挥类似的修饰作用，并且该基因可以是治疗靶点。 该提案的完成将使斑马鱼成为一种有效的脊椎动物模型， 包括基于TTN的DCM的心肌病的预后、诊断和治疗开发。

Dilated cardiomyopathy (DCM) is a disorder with genetic heterogeneity and variable phenotypes. TITIN truncating variants (TTNtvs)- nonsense, frameshift, and essential splice site, has been found to be the most common genetic factor for DCM. However, TTNtvs are also found in reference populations and it remains unclear why pathogenic TTNtvs were mainly found in exons encoding A-band domains, while TTNtvs in other exons such as those affecting the N-terminal Z-disc domain are likely benign. Moreover, patients with the same TTN mutation can exhibit highly variable disease phenotypes, presumably because of different genetic background in personal genomes. To address these two bottlenecks on TTN-based DCM, we leveraged efficient zebrafish genetics. To fill the first knowledge gap on allelic heterogeneity, we utilized genome-editing technology and generated more than 10 ttntvs affecting either Z-disc or A-band exons in zebrafish. To fill the second knowledge gap on variable phenotypes, we established a novel mutagenesis screening-based strategy and successfully identified 4 genetic modifiers for DOX-induced cardiomyopathy. We premise that some of these modifiers and related therapies for DOX-induced cardiomyopathy might also be applicable to TTN-based DCM. We propose to conduct comprehensive genetic studies of these ttntvs and candidate genetic modifiers to elucidate mechanisms and to seek therapeutic strategies for TTNtv-based DCM. In our specific Aim 1, we aim to define phenotypic traits for ttn-based DCM, and to discern toxic peptide, exon usage and cronos hypotheses for allelic heterogeneity of ttn-based DCM. In our specific Aim 2, we will elucidate novel functions of the short ttn-novex3 isoform, and test the hypothesis that N-terminal ttntvs affecting the ttn-novex3 isoform are cardiomyopathy modifiers. In our specific Aim 3, we will determine whether the 4 modifying mutants for DOX-induced cardiomyopathy also exert similar modifying effects on ttn-based DCM, and which gene can be a therapeutic target. Completion of the proposal will establish zebrafish as an efficient vertebrate model that facilitates the prognosis, diagnosis and therapeutic development for cardiomyopathies including TTN-based DCM.