Mitochondrial Aging and Reprogramming

 描述(申请人提供)：衰老是一个复杂的生物过程，其特征是许多细胞、组织和器官的生化、生理和代谢功能逐渐但持续下降。线粒体异常与年龄相关疾病的病因学有关。线粒体含有自己的基因组(MtDNA)，有研究认为，随着年龄的增长，线粒体组织中的mtDNA突变会积累，导致线粒体功能下降，从而导致与年龄相关的疾病和衰老本身。相比之下，雌性生殖系(卵母细胞)线粒体DNA在很大程度上避免了突变，并在最小损害的情况下被保存和复制。这一建议的目的是验证一种假设，即体细胞中与年龄相关的线粒体侵蚀与mtDNA突变有关，mtDNA突变反过来会对来自这些细胞的ipSCs的发育能力产生不利影响。因此，完全替换突变的体细胞mtDNA对于重置人ipSCs的全部发育能力和治疗潜力至关重要。我们建议使用确定的嵌合体试验来评估IPSCs中老化的线粒体和突变的mtDNA对小鼠模型发育和衰老的影响。为了实现我们的目标，我们制定了三个具体目标。在目标1中，我们将产生遗传相同的IPSC系，携带带有原始的年轻卵母细胞线粒体的老的和ntESCs。在目标2中，我们将通过遗传、细胞遗传学、表观遗传学、转录和代谢图谱来定义干细胞。在目标3中，我们将研究干细胞产生的嵌合后代的发育和衰老。该项目完成后，将提供直接的实验证据，证明线粒体基因组完整性的损伤和丧失在衰老过程中发挥着核心作用。我们还将确定体细胞中与年龄相关的线粒体侵蚀是否会影响实验性PSCs的发育潜力。

 DESCRIPTION (provided by applicant): Aging is a complex biological process characterized by a gradual but persistent decline in biochemical, physiological and metabolic function of many cells, tissues and organs. Mitochondrial abnormalities have been implicated in the etiology of age-related diseases. Mitochondria contain their own genome (mtDNA) and it has been proposed that mtDNA mutations in somatic tissues accumulate with age, causing a decline in mitochondrial function, and subsequently, age-related diseases and aging itself. In contrast, female germ line (oocyte) mtDNA largely evades mutagenesis and is preserved and replicated with minimal damage. The objective of this proposal is to test the hypothesis that age-related mitochondrial erosion in somatic cells is associated with mtDNA mutations, which in turn adversely affects the developmental competence of iPSCs derived from these cells. Therefore, complete replacement of mutated somatic cell mtDNA is critical for resetting the full developmental competence and therapeutic potential of human iPSCs. We propose to evaluate the effect of aged mitochondria and mutated mtDNA in iPSCs on development and aging in a mouse model, using the definitive chimera assay. To meet our objective, three Specific Aims have been designed. In Aim 1, we will generate genetically identical iPSC lines carrying old and ntESCs with pristine young oocyte mitochondria. In Aim 2, we will define stem cells by genetic, cytogenetic, epigenetic, transcriptional and metabolic profiling. In Aim 3, we will study the development and aging of chimeric offspring generated from stem cells. When completed, this project will provide the direct experimental proof that accumulation of damage and loss of mitochondrial genome integrity plays a central role in the aging process. We will also determine whether the age related mitochondrial erosion in somatic cells affects the developmental potential of experimental PSCs.