Tafazzin and metabolic reprogramming during cardiomyopathy

项目摘要/摘要 巴特综合征(BTHS)是一种由X-连锁他法津(TAZ)基因突变引起的遗传性疾病 编码线粒体功能所需的一种酶，线粒体是我们细胞的能量源泉。病人 患有遗传性TAZ突变的患者有广泛的临床表现，从中性粒细胞减少到严重的左 心室致密化不全、心肌病和骨骼肌无力。其他线粒体疾病 产生相似但不相同的症状，可能反映了不同类型的线粒体损伤 不同的组织。因此，对BTHS和其他线粒体疾病的分子发病机制的理解是 对公众的健康具有非常重要的意义。然而，目前还不清楚如何以及为什么会出现故障 TAZ功能主要损害男性的心脏、免疫和肌肉骨骼系统。 此外，与其他人类遗传病一样，建立适当的BTHS小鼠模型是 必须在体内研究BTHS并测试潜在的治疗方法。尽管其他人的工作已经表明 他法津在心脏中的重要作用，这就需要使用替代的小鼠模型，包括 可诱导的shRNA Taz敲除和“混合Taz嵌合体”，既不能反映BTHS的发病机制，也不能反映BTHS的发病机制 对其进行性临床表现进行表型分析。在初步研究中，我们克服了这一关键限制 通过将BTHS患者的TAZ突变编辑为同源保守序列进行体内BTHS综合征的研究 CRISPR/CAS技术检测小鼠Taz基因残留量初步数据显示，我们针对患者的新型标签 点突变雄性小鼠(在正常水平表达突变Taz的TazPM)显示出BTHS的所有关键指标，来自 致死性胎儿和出生后致死性非致密性心肌病和心磷脂受损的粒细胞生成受损 生物合成。为了测试哪些谱系主要受影响，我们生成了一个心肌细胞限制性FLOXED (TazcKO)突变体，患有线粒体和心磷脂缺陷的出生后心肌病。我们将测试 我们的假设是，缺乏心磷脂和线粒体不成熟阻碍了子宫小梁形成，同时丢失了 TAZ催化活性决定了出生后低血糖心脏病理、糖酵解的时间和严重程度 重新编程和生存。因此，我们正在积极地进行多学科的产前和产后纵向研究 这些独特的小鼠模型的心血管表型和代谢测试以了解体内 与人类的病程进行比较，并测试他法津替代疗法和体内 药物改善可以减轻我们患者特异性小鼠中危及生命的BTHS出生缺陷 模特。总而言之，这一基于精确医学的提议将提供对分子的机械性见解 TAZ中断导致的各种心肌病的发病机制，解开新的证据线索- 推动候选疗法，并帮助创建针对患者的平台，以测试个性化治疗策略 在未来的研究中用于BTHS。

PROJECT SUMMARY / ABSTRACT Barth syndrome (BTHS) is a genetic disorder due to mutations in the X-linked tafazzin (TAZ) gene encoding an enzyme required for the functioning of mitochondria, the energy powerhouses of our cells. Patients with inherited TAZ mutations suffer from a wide range of clinical manifestations, from neutropenia to severe left ventricular noncompaction cardiomyopathy and skeletal muscle weakness. Other mitochondrial diseases produce similar but not identical symptoms, possibly reflecting distinct types of mitochondrial impairment in different tissues. Thus, understanding of molecular pathogenesis of BTHS and other mitochondriopathies is highly significant for the health of the general public. However, it is not mechanistically clear how and why faulty TAZ function produces impairment of largely the male heart, immune and musculoskeletal systems. Furthermore, the establishment of proper mouse models of BTHS, as in other human genetic diseases, is imperative to study BTHS in vivo and test potential therapies. Although the work of others has shown an important role for tafazzin in the heart, this has necessitated the use of alternative mouse models, including inducible shRNA Taz knockdown and “mixed Taz chimeras”, that are unable to mirror BTHS pathogenesis nor phenocopy its progressive clinical manifestations. In preliminary studies, we overcame this crucial limitation of in vivo BTHS syndrome research by editing a BTHS patient’s TAZ mutation into the orthologous conserved residue of murine Taz gene by CRISPR/CAS technology. Preliminary data show our novel patient-specific Taz point mutant male mice (TazPM that express mutant Taz at normal levels) display all key indicators of BTHS, from impaired granulopoiesis to lethal fetal and postnatal non-compaction cardiomyopathy and impaired cardiolipin biosynthesis. In order test which lineages are primarily affected, we generated a cardiomyocyte-restricted floxed (TazcKO) mutant that develops postnatal cardiomyopathy with mitochondria and cardiolipin defects. We will test our hypothesis that lack of cardiolipin and mitochondrial immaturity impedes in utero trabeculation whilst loss of Taz catalytic activity dictates the timing and severity of postnatal hypoglycemic heart pathology, glycolytic reprogramming and survival. Therefore, we are actively pursuing multidisciplinary pre- and postnatal longitudinal cardiovascular phenotyping and metabolic testing of these unique mouse models to understand the in vivo course of disease in comparison to humans, and testing whether TAFAZZIN replacement therapy and in vivo pharmacological amelioration can mitigate the life-threatening BTHS birth defects in our patient-specific mouse model. Together, this precision medicine-based proposal will provide mechanistic insights into the molecular pathogenesis of the various cardiomyopathies resulting from TAZ disruption, unravel novel leads for evidence- driven candidate therapies and help create patient-specific platforms to test personalized therapeutic strategies for BTHS in future studies.