MRC TS Award: Investigating the role of cardiolipin metabolism in mitochondrial DNA replication and mitochondrial division

MRC TS 奖：研究心磷脂代谢在线粒体 DNA 复制和线粒体分裂中的作用

• 批准号: MR/X02363X/1
• 负责人: Robert Pitceathly
• 金额: $ 57.81万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FX02363X%2F1
• 关键词: MRC; TS; Award; Investigating; role

Mitochondria provide the major source of energy in human cells and control numerous metabolic pathways. Thirteen subunits of the energy producing machinery are encoded by DNA present in the mitochondria (mitochondrial DNA, mtDNA); while most of the mitochondrial proteome (>1,500 predicted proteins) is encoded by the nuclear genome and are actively imported into the organelles from the cytosol. Mitochondrial diseases, inherited conditions caused by mutations in nuclear- and mtDNA-encoded mitochondrial genes that impair mitochondrial function, are among the most common genetic neurological disorders, affecting 1 in 4,300 individuals. They often cause devastating illness associated with severe disability and shortened lifespan in children and adults. Unfortunately, there are currently no effective treatments that halt or reverse progression of the disease. One emerging, but poorly characterised, category of mitochondrial diseases relates to impaired phospholipid (PL) metabolism. Cardiolipin (CL) is a PL found only in mitochondria with numerous essential mitochondrial functions. CL biosynthesis is a complex process, involving the endoplasmic reticulum (ER), a network of membranous tubules within the cytoplasm of the cell, continuous with the nuclear membrane, and the mitochondria. ER provides an important precursor of CL biosynthesis known as phosphatidic acid (PA). Crucial for the transfer of PA from the ER to the IMM is the TRIAP1-PRELID1 complex. Further evidence for the intrinsic connection between the ER and mitochondria has recently emerged with evidence that mtDNA replication occurs at ER-mitochondria contact sites, thus coupling mtDNA synthesis and mitochondrial division. However, the mechanism that links mtDNA synthesis to mitochondrial division, and the impact of perturbed ER-mitochondria contact sites on mtDNA replication, remains poorly understood.In my original proposal, I reported the first, homozygous pathogenic mutation in TRIAP1, a gene involved in CL biosynthesis. Multiple mtDNA deletions were detected in the patient's muscle, implicating TRIAP1 in mtDNA replication. One exciting development during the 2nd year of my fellowship was the identification of a 2nd patient with different, novel homozygous TRIAP1 variant. Importantly, multiple mtDNA deletions were again present in muscle, as observed in the first case, thus supporting my initial hypothesis that TRIAP1 is a novel regulator of mtDNA maintenance.Identification of a 2nd TRIAP1 case was pivotal, given it: 1) confirmed the biological and medical importance of this pathway for human pathology; and 2) provided unrelated, biological material for functional work to complement the previously available cell line. This represents a unique opportunity to advance fundamental understanding of the role of CL metabolism in mtDNA replication and mitochondrial division and introduces TRIAP1 as a novel regulator of mtDNA replication and segregation. Despite the 2nd TRIAP1 case representing significant "added value" to my intermediate fellowship, time and resource have been redirected away from my original application to adapt the study design and account for this development. In addition, experimental work at UCL Queen Square Institute of Neurology, and at collaborator laboratories, was delayed due to temporary closures of the laboratories (April to July 2020) and stricter social distancing rules preventing two researchers using lab space at the same time (July 2020 to April 2021) caused by COVID-19 restrictions. Transition Support would therefore enable me to complete experiments necessary to fully address and build on my original aim - to determine how CL metabolism influences mtDNA replication and mitochondrial division - and the new models and additional data generated will strongly support my future application for an MRC Senior Fellowship.

线粒体提供了人类细胞中的主要能源，并控制了许多代谢途径。能量产生机械的13个亚基由线粒体中存在的DNA（线粒体DNA，mtDNA）编码；虽然大多数线粒体蛋白质组（> 1,500个预测蛋白）由核基因组编码，并从细胞质中积极进口到细胞器中。线粒体疾病是由核和MTDNA编码的线粒体基因损害线粒体功能引起的遗传疾病，是最常见的遗传神经系统疾病之一，影响了4,300名患者中有1个。它们常常引起与严重残疾和儿童和成人寿命相关的毁灭性疾病。不幸的是，目前尚无有效的治疗方法可以阻止或逆转疾病的进展。线粒体疾病的一种新兴但特征性的类别与磷脂（PL）代谢受损有关。 Cardiolipin（CL）是仅在线粒体中发现的具有许多必需线粒体功能的PL。 CL生物合成是一个复杂的过程，涉及内质网（ER），这是细胞细胞质内的膜小管网络，与核膜连续，并连续。 ER提供了称为磷脂酸（PA）的Cl生物合成的重要前体。对PA从ER转移到INM的至关重要的是Triap1-Prelid1复合物。最近出现了有关ER和线粒体之间内在联系的进一步证据，证明MtDNA复制发生在ER点线粒体接触位点，因此将mtDNA合成和线粒体分裂偶联。但是，将mtDNA合成与线粒体分裂联系起来的机制，以及扰动的er-mitochondria接触位点对mtDNA复制的影响仍然很糟糕。 Cl生物合成。在患者的肌肉中检测到了多个mtDNA缺失，这意味着triap1在mtDNA复制中。在我团契的第二年，一个令人兴奋的发展是确定了一个具有不同新型纯合Triap1变体的第二名患者。重要的是，肌肉中再次存在多个mtDNA缺失，如第一种情况所观察到的，因此支持我最初的假设，即Triap1是mtDNA维持的新调节剂。鉴定第二个Triap1病例的确认是关键的，鉴于它是至关重要的：1）证实了生物学。这种途径对人类病理的重要性； 2）为功能工作提供了无关的生物学材料，以补充先前可用的细胞系。这是一个独特的机会，可以促进对Cl代谢在mtDNA复制和线粒体分裂中的作用的基本理解，并引入Triap1作为MTDNA复制和隔离的新型调节剂。尽管第二个Triap1案例代表了我的中级奖学金的“附加值”，但时间和资源已从我的原始应用中重定向，以适应研究设计并说明这一发展。此外，由于实验室的临时关闭（4月至2020年7月），UCL女王广场神经病学研究所和合作者实验室的实验性工作被推迟，并更严格的社会距离规则，以防止两名研究人员同时使用实验室空间（7月） 2020年至2021年4月）是由COVID-19限制引起的。因此，过渡支持将使我能够完成必要的实验，以完全解决和建立我的最初目标 - 确定CL代谢如何影响mtDNA复制和线粒体划分 - 新的模型和其他生成的数据将强烈支持我未来对MRC高级的应用程序奖学金。