Tafazzin and metabolic reprogramming during cardiomyopathy

项目总结/摘要 Barth综合征（BTHS）是一种遗传性疾病，由于X连锁tafazzin（TAZ）基因突变 编码一种线粒体功能所需的酶，线粒体是我们细胞的能量来源。患者 具有遗传性TAZ突变的患者患有广泛的临床表现，从中性粒细胞减少症到严重的左 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，了解BTHS和其他神经系统疾病的分子发病机制是必要的。 对公众健康意义重大。然而，从机理上讲， TAZ功能主要损害男性的心脏、免疫和肌肉骨骼系统。 此外，建立适当的BTHS小鼠模型，就像在其他人类遗传疾病中一样， 必须在体内研究BTHS并测试潜在的治疗方法。虽然其他人的工作表明， 由于tafazzin在心脏中的重要作用，因此有必要使用替代小鼠模型，包括 可诱导的ShRNATaz敲低和“混合Taz嵌合体”不能反映BTHS发病机制， 其渐进的临床表现。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突变编辑到BTHS患者的正向保守基因中， 通过CRISPR/CAS技术对小鼠Taz基因残基进行测序。初步数据显示，我们的新型患者特异性Taz 点突变雄性小鼠（以正常水平表达突变Taz的TazPM）显示BTHS的所有关键指标，从 致死性胎儿和出生后致密化不全心肌病的粒细胞生成受损和心磷脂受损 生物合成为了测试哪些谱系主要受到影响，我们产生了心肌细胞限制性的floxed （TazcKO）突变体，其发展具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，心磷脂缺乏和线粒体不成熟阻碍了子宫小梁形成， Taz催化活性决定了出生后低血糖心脏病理学的时间和严重程度， 重新编程和生存因此，我们正在积极开展多学科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 与人类相比的病程，并测试TAFAZZIN替代疗法和体内 药理学改善可以减轻我们的患者特异性小鼠中危及生命的BTHS出生缺陷 模型总之，这种基于精确医学的建议将为分子生物学提供机制见解。 TAZ破坏导致的各种心肌病的发病机制，揭示了新的证据线索， 驱动的候选疗法，并帮助创建患者特定的平台，以测试个性化的治疗策略 在未来的研究中，

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.