Nuclear mechanics and mechanotransduction in muscular laminopathies

项目摘要 这个项目的长期目标是确定人类LMNA基因的突变是如何编码核的 包膜蛋白(NE)层蛋白A和C会导致严重的心肌和骨骼肌疾病。这项研究是 重要的是因为LMNA基因的突变导致了大约10%的遗传 扩张型心肌病和LMNA相关的心肌病预后特别差。 患有LMNA相关性肌营养不良的个体患有衰弱的进行性肌肉萎缩和 死于扩张型心肌病。到目前为止，还没有有效的治疗心脏和骨骼疾病的方法。 LMNA突变引起的肌肉缺陷，目前尚不清楚LMNA突变是如何导致肌肉- 特定的缺陷。对该病发病机制的不完全理解是导致 开发有效的治疗方法。基于最近公布的广泛的初步数据，这个项目 为影响心肌和骨骼肌的椎板病的发病机制提出一个新的假说：LMNA 与横纹肌疾病相关的突变降低了核机械稳定性。骨骼和心脏 组织，然后脆弱的核容易机械地引起NE的损伤(NE破裂)，这是由于 在肌肉细胞收缩和成熟过程中，作用于肌核的细胞骨架力。北东向断裂导致 DNA损伤和DNA损伤反应通路的激活，导致细胞死亡、衰老和 代谢受损是进行性心肌和骨骼肌缺陷的原因。其他内容 机制，如转录调节紊乱和增加的活性氧物种的产生， 可能进一步促进DNA损伤的增加和DNA损伤反应通路的激活 LMNA突变的肌肉细胞。这项拟议的工作利用了几种体外和体内模型和 在PI的实验室中定制的用于测量核力学和机械性能的分析 对活细胞和固定组织造成损伤。拟议的项目旨在：(1)确定分子和 导致NE断裂、DNA损伤和DNA损伤反应增加的生物物理机制 椎板病中骨骼肌细胞和心肌细胞的激活；(2)确定导致 NE断裂、DNA损伤和DNA损伤反应激活对横纹肌细胞死亡和功能障碍； 以及(3)评估是否抑制了过度活跃的DNA损伤反应途径或减少了对 在LMNA相关疾病的小鼠模型中，核改善了心脏和骨骼肌的健康。这个 拟议的研究将确定在椎板病中观察到的核损伤的功能作用，并提供新的 对影响心肌和骨骼肌的椎板病的发病机制的洞察，有可能 发现新的治疗靶点和策略，可显著增强现有的治疗选择 对于受影响的个人。

Project Summary The long-term goal of this project is to determine how mutations in the human LMNA gene encoding the nuclear envelope (NE) proteins lamin A and C cause severe cardiac and skeletal muscle diseases. This research is important because mutations in the LMNA gene are responsible for approximately 10% of all genetically inherited cases of dilated cardiomyopathy, and LMNA-associated cardiomyopathies have a particularly poor prognosis. Individuals with LMNA-associated muscular dystrophy suffer from debilitating progressive muscle wasting and die from dilated cardiomyopathy. To date, no effective treatments are available for the cardiac and skeletal muscle defects caused by LMNA mutations, and it remains unclear how LMNA mutations result in muscle- specific defects. The incomplete understanding of the disease pathogenesis presents a major hurdle in the development of effective treatments. Building on recently published and extensive preliminary data, this project proposes a novel hypothesis for the pathogenesis of laminopathies affecting cardiac and skeletal muscle: LMNA mutations associated with striated muscle disease reduce nuclear mechanical stability. In skeletal and cardiac tissues, the fragile nuclei are then prone to mechanically induced damage to the NE (‘NE rupture’) due to cytoskeletal forces acting on myonuclei during muscle cell contraction and maturation. The NE rupture results in DNA damage and activation of DNA damage response pathways, which lead to cell death, senescence, and metabolic impairment responsible for the progressive cardiac and skeletal muscle defects. Additional mechanisms, such as disturbed transcriptional regulation and increased production of reactive oxygen species, may further contribute to the increased DNA damage and activation of DNA damage response pathways in the LMNA mutant muscle cells. The proposed work takes advantage of several in vitro and in vivo models and assays that were custom-developed in the PI’s laboratory to measure nuclear mechanics and mechanically induced damage in living cells and fixed tissues. The proposed project aims to: (1) determine the molecular and biophysical mechanisms that cause the increased NE rupture, DNA damage, and DNA damage response activation in skeletal and cardiac muscle cells in laminopathies; (2) identify the molecular pathways leading from NE rupture, DNA damage, and DNA damage response activation to striated muscle cell death and dysfunction; and (3) evaluate if inhibiting hyperactive DNA damage response pathways or reducing physical stress on the nucleus improves cardiac and skeletal muscle health in mouse models of LMNA-associated disease. The proposed studies will establish the functional role of nuclear damage observed in laminopathies and provide new insights into the pathogenesis of laminopathies affecting cardiac and skeletal muscle, with the potential to discover novel therapeutic targets and strategies that could significantly enhance the treatment options available for affected individuals.