Elevated mitochondrial fusion and function in Down syndrome

唐氏综合症患者线粒体融合和功能增强

• 批准号: 9894475
• 负责人: Beverly A Rothermel
• 金额: $ 202.19万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-20 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9894475
• 关键词: Address; Affect; Aging; Alzheimer like pathology; Alzheimer' s Disease; American; Astrocytes; CRISPR/Cas technology; Calcineurin; Candidate Disease Gene; Cardiac; Cardiac Myocytes; Cells; Chromosomes, Human, Pair 21; Clinical Trials; Congenital Heart Defects; Coupled; DNA; Defect; Diabetes Mellitus; Diploidy; Dominant Genes; Down Syndrome; Family; Feedback; Fluoxetine; Frequencies; General Population; Genes; Genomic Segment; Guide RNA; Human Chromosomes; Individual; Intellectual functioning disability; Knowledge; Laboratories; Live Birth; Mediating; Metabolic; Mitochondria; Molecular; Morphology; Nature; Neurons; Oxidative Stress; Patent Ductus Arteriosus; Pathology; Pathway interactions; Patients; Pharmacology; Phenotype; Population; Presenile Alzheimer Dementia; Process; Production; Protein Dephosphorylation; Protein phosphatase; Proteins; Reporting; Risk; Small Interfering RNA; Testing; Therapeutic; Time; Tissues; Trisomy; calcineurin phosphatase; design; dosage; early onset; genome editing; improved; indexing; induced pluripotent stem cell; inhibitor/antagonist; insight; mitochondrial dysfunction; mitochondrial metabolism; mouse model; oxidative damage; prevent; repaired; stem cell differentiation; targeted treatment; tool

Project Summary/Abstract Down syndrome (DS) is the most common cause of intellectual disabilities, congenital heart defects and early-onset Alzheimer’s disease. It occurs at a frequency of almost 1 in 700 live births, and is due to the complete or partial trisomy of human chromosome 21 (Hsa21). However, the specific molecular mechanisms giving rise to DS pathologies remain elusive. Mitochondrial dysfunction and oxidative stress are widely reported in cells and tissues from DS subjects and are thought to be important contributors to the early-aging, degenerative nature of DS. Our laboratory recently reported that the mitochondrial network in induced pluripotent stem cells (iPSCs) derived from DS patients (T21) is more fused and metabolically active than the mitochondrial population in isogenic, diploid iPSCs. This remarkable finding suggests that, on a fundamental level, DS mitochondria may be super-functional rather than dysfunctional. We went on to show that siRNA depletion of Regulator of Calcineurin 1 (RCAN1/DSCR1), a gene on Hsa21, is sufficient to restore a more normal mitochondrial morphology and function to T21 iPSCs. RCAN1 was previous identified by our lab as a feedback inhibitor of the Ca2+-activated protein phosphatase calcineurin. Calcineurin-mediated dephosphorylation of Drp1, an important regulator of mitochondrial dynamics, promotes mitochondrial fission, a process that tends to decrease mitochondrial metabolic activity but that is essential for turnover and repair of damaged mitochondria. We postulate that increased dosage of RCAN1 in DS suppresses the process of calcineurin-mediated mitochondrial fission. Our underlying hypothesis is that elevated metabolic activity and ROS production, coupled with a decreased capacity to remove damaged mitochondria, increases cumulative, oxidative damage over time in individuals with DS. Our proposed studies will (Aim 1) Test this hypothesis at the level of early stem cell differentiation and cell fate commitment by assessing changes in mitochondrial function and indices of cellular damage during differentiation of isogenic triploid T21 and diploid D21 iPSCs. (Aim 2) Use the powerful tool of CRISPR-Cas9 genomic editing to test whether trisomy of RCAN1, or other loci, is sufficient to drive the hyper-fused phenotype, and (Aim 3) Explore possible therapeutic approaches to restoring normal mitochondrial function using newly identified compounds capable of preventing RCAN1 from inhibiting calcineurin. These studies address an important gap in our knowledge regarding the molecular causes of DS. Identifying the dominant genes or molecular pathways involved would open the possibility for developing targeted therapies to improve the lives of affected individuals and their families. In addition, many of the pathologies that occur with high frequency in DS are also common in the general population, although at a lower frequency, such as cardiac cushion defects, patent ductus arteriosus, diabetes, and Alzheimer’s disease. Thus, a better understanding of the specific mechanisms contributing to the DS phenotype is likely to yield insights that will also benefit a much wider population.

项目总结/摘要 唐氏综合征（DS）是智力残疾、先天性心脏缺陷和早发性 老年痴呆症它发生的频率几乎是1/700活产，是由于完全或部分三体 人类21号染色体（Hsa 21）。然而，引起DS病理学的特定分子机制仍然存在， 难以捉摸。线粒体功能障碍和氧化应激在DS受试者的细胞和组织中被广泛报道， 被认为是DS的早期老化和退行性本质的重要贡献者。我们的实验室最近报告说， 来自DS患者（T21）的诱导多能干细胞（iPSC）中的线粒体网络更加融合， 在同基因的二倍体iPSC中，线粒体群体比线粒体群体代谢活跃。这一惊人的发现表明， 在基本水平上，DS线粒体可能是超功能的而不是功能障碍的。我们继续展示， siRNA去除Hsa 21上的钙调神经磷酸酶1（RCAN 1/DSCR 1）基因足以恢复正常的 线粒体形态和功能与T21 iPSC的关系。RCAN 1以前被我们的实验室鉴定为反馈抑制剂 钙激活的蛋白磷酸酶钙调神经磷酸酶。钙调神经磷酸酶介导的Drp 1去磷酸化， 线粒体动力学的调节因子，促进线粒体分裂，这是一个倾向于减少线粒体 代谢活动，但这是必不可少的周转和修复受损的线粒体。我们假设， DS中RCAN 1剂量抑制钙调神经磷酸酶介导的线粒体分裂过程。我们的基本 假设是代谢活性和ROS产生的升高，加上清除能力的降低， 受损的线粒体，随着时间的推移，增加了DS患者的累积氧化损伤。我们提出的 研究将（目的1）在早期干细胞分化和细胞命运定型的水平上检验这一假设， 评估同基因三倍体T21分化过程中线粒体功能和细胞损伤指数的变化 和二倍体D21 iPSC。(Aim 2）使用CRISPR-Cas9基因组编辑的强大工具来测试是否存在三体性。 RCAN 1或其他基因座足以驱动超融合表型，并且（目的3）探索可能的治疗性基因表达。 使用新鉴定的能够预防RCAN 1的化合物恢复正常线粒体功能的方法 抑制钙调磷酸酶。 这些研究解决了我们对DS分子病因的认识中的一个重要空白。识别主导 相关基因或分子途径将为开发靶向治疗以改善患者的生活提供可能性。 受影响的个人及其家庭。此外，在DS中以高频率发生的许多病理也是 在一般人群中常见，尽管频率较低，如心脏垫缺陷、导管未闭 糖尿病和老年痴呆症因此，更好地了解有助于实现这一目标的具体机制， DS表型很可能产生的见解，也将有利于更广泛的人群。