Deciphering the role of RANK/RANKL/OPG in skeletal muscle

破译 RANK/RANKL/OPG 在骨骼肌中的作用

• 批准号: RGPIN-2016-05845
• 负责人: Frenette, Jérôme
• 金额: $ 2.55万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=709861
• 关键词: Deciphering; role; RANK; RANKL; OPG

The discovery of RANK/RANKL/OPG the receptor-activator of nuclear factor B (RANK), the receptor-activator of nuclear factor B ligand (RANKL), and the osteoprotegerin (OPG) pathway has been among the most important advances in bone biology and disease. RANK/RANKL/OPG form a key cytokine system for regulating osteoclast differentiation and function. RANKL is expressed by osteoblasts while RANK, its receptor, is expressed on pre-osteoclastic cells. The RANK/RANKL interaction induces the formation of multinucleated mature osteoclasts, ultimately causing bone resorption. However, the third protagonist, OPG, is also produced by osteoblasts and exerts an inhibitory effect on pre-osteoclastic differentiation. OPG, by binding to RANKL, inhibits the RANKL/RANK interaction and the subsequent osteoclastogenesis. The fact that OPG-null mice are osteoporotic is testimony to the physiological importance of OPG. OPG also serves as a decoy receptor for the tumour necrosis factor-related apoptosis-inducing ligand and increases cell survival by blocking the pro-apoptotic effects of the RANK/RANKL interaction. OPG is thus a very efficient anti-resorptive and anti-apoptotic agent. However, our recent publication in Am. J. Pathol. (2015) convincingly showed that OPG-Fc completely restores the function of fast-twitch extensor digitorum longus muscles and significantly improves the function of slow-twitch soleus and diaphragm muscles in mdx mice, indicating that OPG is not only a protector of bone but also skeletal muscles. In this proposal, we will use genetic and pharmacological approaches to determine how RANK/RANKL/OPG triad, known for its role in bone regulation, regulates skeletal muscle phenotype, muscle function and SERCA-2a content and SERCA activity. We have also accumulated substantial evidence to support the observation that RANKL binds to muscle RANK but RANKL/OPG would also have its own muscle receptor acting directly on skeletal muscle. We thus intend to pursue three specific aims over the next 5 years. (1) To understand the interplay between OPG, RANKL, mechanical loading and extracellular Ca2+ in muscle cells in culture. (2) To determine how extracellular Ca2+ influences muscle performance in dystrophic muscle RANK deficient mice. (3) To demonstrate that RANKL influences SERCA-2a content in C2C12 myotubes through a RANKL/RANK interaction-independent mechanism. Together, this basic research proposal highlights the mutual cooperative interactions between skeletal muscle and bone and should open new physiological mechanisms for RANK/RANKL/OPG pathway.

RANK/RANKL/OPG、核因子 B 受体激活剂 (RANK)、核因子 B 配体受体激活剂 (RANKL) 和骨保护素 (OPG) 途径的发现是骨生物学和疾病领域最重要的进展之一。 RANK/RANKL/OPG形成调节破骨细胞分化和功能的关键细胞因子系统。 RANKL 由成骨细胞表达，而其受体 RANK 在前破骨细胞上表达。 RANK/RANKL 相互作用诱导多核成熟破骨细胞的形成，最终引起骨吸收。然而，第三个主角OPG也是由成骨细胞产生的，对破骨细胞分化前发挥抑制作用。 OPG 通过与 RANKL 结合，抑制 RANKL/RANK 相互作用以及随后的破骨细胞生成。 OPG 缺失小鼠骨质疏松的事实证明了 OPG 的生理重要性。 OPG 还充当肿瘤坏死因子相关凋亡诱导配体的诱饵受体，并通过阻断 RANK/RANKL 相互作用的促凋亡作用来增加细胞存活率。因此，OPG 是一种非常有效的抗再吸收和抗凋亡剂。然而，我们最近在 Am 上发表的文章。 J.帕索尔. (2015)令人信服地表明，OPG-Fc完全恢复了mdx小鼠快肌长伸肌的功能，并显着改善了慢肌比目鱼肌和膈肌的功能，表明OPG不仅是骨骼的保护者，也是骨骼肌的保护者。 在本提案中，我们将使用遗传和药理学方法来确定以其在骨调节中的作用而闻名的 RANK/RANKL/OPG 三联体如何调节骨骼肌表型、肌肉功能以及 SERCA-2a 含量和 SERCA 活性。我们还积累了大量证据来支持 RANKL 与肌肉 RANK 结合的观察结果，但 RANKL/OPG 也有其自己的肌肉受体直接作用于骨骼肌。因此，我们打算在未来五年内实现三个具体目标。 (1) 了解培养的肌肉细胞中 OPG、RANKL、机械负荷和细胞外 Ca2+ 之间的相互作用。 (2) 确定细胞外 Ca2+ 如何影响营养不良性肌肉 RANK 缺陷小鼠的肌肉性能。 (3)证明RANKL通过RANKL/RANK相互作用独立机制影响C2C12肌管中SERCA-2a含量。 总之，这项基础研究提案强调了骨骼肌和骨骼之间的相互协作相互作用，并为 RANK/RANKL/OPG 通路开辟新的生理机制。