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

基本信息

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

项目摘要

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.

线粒体提供人体细胞的主要能量来源并控制许多代谢途径。能量产生机制的 13 个亚基由线粒体中的 DNA（线粒体 DNA，mtDNA）编码；而大多数线粒体蛋白质组（超过 1,500 种预测蛋白质）由核基因组编码，并主动从细胞质导入细胞器。线粒体疾病是由核和 mtDNA 编码的线粒体基因突变引起的遗传性疾病，会损害线粒体功能，是最常见的遗传性神经系统疾病之一，每 4,300 人中就有 1 人受到影响。它们通常会导致严重的疾病，导致儿童和成人严重残疾并缩短寿命。不幸的是，目前没有有效的治疗方法可以阻止或逆转疾病的进展。一类新兴但尚未明确描述的线粒体疾病与磷脂 (PL) 代谢受损有关。心磷脂 (CL) 是一种仅在线粒体中发现的 PL，具有多种重要的线粒体功能。 CL 生物合成是一个复杂的过程，涉及内质网 (ER)、细胞质内与核膜连续的膜小管网络和线粒体。 ER 提供了 CL 生物合成的重要前体，称为磷脂酸 (PA)。 PA 从 ER 转移到 IMM 的关键是 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，有证据表明 mtDNA 复制发生在 ER-线粒体接触位点，从而将 mtDNA 合成和线粒体分裂耦合起来。然而，将 mtDNA 合成与线粒体分裂联系起来的机制，以及受干扰的 ER-线粒体接触位点对 mtDNA 复制的影响，仍然知之甚少。在我最初的提议中，我报道了 TRIAP1 中的第一个纯合致病性突变，TRIAP1 是一个参与线粒体分裂的基因。 CL生物合成。在患者的肌肉中检测到多个 mtDNA 缺失，表明 TRIAP1 参与了 mtDNA 复制。在我的研究金的第二年，一个令人兴奋的进展是鉴定出第二位具有不同的新型纯合 TRIAP1 变异的患者。重要的是，正如在第一个病例中观察到的那样，肌肉中再次存在多个 mtDNA 缺失，从而支持了我最初的假设，即 TRIAP1 是 mtDNA 维持的新型调节因子。第二个 TRIAP1 病例的识别至关重要，因为：1）证实了生物学以及该途径对人类病理学的医学重要性； 2) 为功能性工作提供不相关的生物材料，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 复制和分离的新型调节剂。尽管第二个 TRIAP1 案例对我的中级研究金具有重要的“附加价值”，但时间和资源已从我最初的申请中转移出来，以适应研究设计并考虑到这一发展。此外，由于实验室暂时关闭（2020 年 4 月至 7 月）以及更严格的社交距离规则阻止两名研究人员同时使用实验室空间（2020 年 7 月），伦敦大学学院皇后广场神经病学研究所和合作实验室的实验工作被推迟。 2020 年至 2021 年 4 月）由 COVID-19 限制造成。因此，过渡支持将使我能够完成必要的实验，以充分解决和建立我最初的目标 - 确定 CL 代谢如何影响 mtDNA 复制和线粒体分裂 - 并且生成的新模型和附加数据将有力支持我未来申请 MRC Senior奖学金。