Targeting PTEN to ameliorate muscular dystrophy in a mouse model

靶向PTEN改善小鼠肌营养不良症的实验研究 摘要 Duchenne肌营养不良症(DMD)是一种衰弱和致命的疾病，其原因是 骨骼肌是运动和呼吸的关键。患者最终会失去行走和活动能力，而且 呼吸衰竭。目前还没有治愈这种疾病的方法。这项拟议的研究旨在 提供对PTEN蛋白如何参与DMD发病机制的基本了解，并探索 新的PTEN靶向治疗策略在小鼠模型MDX小鼠中治疗DMD。申请人的团队 最近发现磷酸酶和紧张素同源蛋白(PTEN)是一种新的肌肉发生调节因子。PTEN是一种 磷酸酶，抵消生长因子介导的对肌肉生长和修复至关重要的信号 通过激活肌肉干细胞(也称为肌肉卫星细胞，MuSCs)。有趣的是，我们和其他人 发现PTEN在健康成人肌肉中的水平很低，但在DMD患者的骨骼肌中却升高 和动物模型，表明PTEN上调可能有助于疾病的进展。为了证实这一点， 我们在初步研究中表明，肌肉特异性敲除Pten基因可以改善肌肉病理和 恢复MDX小鼠的肌肉功能。这些令人兴奋的结果证实了PTEN的抑制可能被翻译成 来治疗人类的DMD。然而，靶向PTEN及其信号转导需要彻底了解 营养不良肌肉中PTEN功能的细胞和分子机制将被研究 在拟议研究的第一部分。为了进一步探索这一发现的可译性，我们在 初步研究PTEN的药理抑制剂(即VO-OHpic)对mdx小鼠的作用。我们 结果表明，VO-OHpic强效改善肌肉的健康和功能，没有明显的副作用。为了进一步 为了提高VO-OHpic在体内的安全性，我们研制了一种纳米颗粒(NP)介导的递送系统 它可以将VO-OHpic特异性地输送到肌肉细胞，以实现药物的持续释放并限制副作用。 在拟议研究的第二部分，我们将进一步优化这一原型药物输送系统，并 检测其在MDX小鼠体内的有效性和安全性。研究完成后，我们不仅获得了 对PTEN在营养不良肌肉中的病理功能的研究势在必行，但也开发了一种新的 PTEN在肌肉中的持续药物抑制给药系统改善 临床前动物模型中的肌肉病理和改善肌肉功能。这些结果将建立一个 为这一治疗人类DMD的有前景的治疗策略的临床翻译奠定了坚实的基础。这个 肌肉靶向NP药物输送系统也可用于输送其他疗法来治疗DMD或 其他退行性疾病。

Targeting PTEN to ameliorate muscular dystrophy in a mouse model Abstract Duchenne muscular dystrophy (DMD) is a debilitating and lethal disease due to degeneration and wasting of skeletal muscles that are key for motility and respiration. Patients eventually lose ambulation and mobility, and experience respiratory failure. Currently there is no cure for this disease. The proposed research aims to provide basic understanding of how PTEN protein might be involved in the pathogenesis of DMD and explore a new PTEN-targeting therapeutic strategy to treat DMD in a mouse model, the mdx mice. The applicant’s team has recently identified phosphatase and tensin homolog (PTEN) as a new regulator of myogenesis. PTEN is a phosphatase that counteracts the growth factor-mediated signaling that is critical for muscle growth and repair through activation of muscle stem cells (also called muscle satellite cells, MuSCs). Interestingly, we and others found that PTEN levels are very low in healthy adult muscles but elevated in skeletal muscles of DMD patients and animal models, suggesting that PTEN upregulation may contribute to disease progression. To confirm this, we show in preliminary studies that muscle-specific knockout of Pten gene ameliorates muscle pathology and restores muscle function in mdx mice. These exciting results confirm that inhibition of PTEN may be translated to treat DMD in humans. However, targeting PTEN and its signaling requires a thorough understanding of the cellular and molecular mechanisms underlying PTEN function in dystrophic muscle, which will be investigated in the first part of the proposed study. To further explore the translatability of this discovery, we tested in preliminary studies the effect of a pharmacological inhibitor of PTEN (namely VO-OHpic) in mdx mice. We showed that VO-OHpic robustly improves muscle health and function without obvious side effects. To further improve the safety of VO-OHpic in vivo, we generated a nanoparticle (NP)-mediated delivery system with which to deliver VO-OHpic specifically to muscle cells to achieve sustained drug release and limit side effects. In the second part of the proposed research, we will further optimize this prototype drug delivery system and examine its utility and safety in mdx mice. Upon completion of the study, we will have not only gained imperative insights into the pathological function of PTEN in dystrophic muscle, but also developed a novel drug delivery system for sustained pharmacological inhibition of PTEN specifically in the muscle to ameliorate muscle pathology and improve muscle function in a preclinical animal model. These results will establish a solid foundation for clinical translation of this promising therapeutic strategy to treat DMD in humans. The muscle-targeting NP drug delivery system may also be adapted to deliver other therapeutics to treat DMD or other degenerative diseases.