Regulation of GDF11 by extracellular mechanisms

项目概述：生长分化因子11（GDF 11）和GDF 8是两种密切相关的分子 更大的TGFβ超家族。虽然GDF 8以其在肌肉质量调节中的作用而闻名，但证据表明， 现在正在出现，暗示GDF 11是对多种生物系统具有有益影响的因子。 GDF 11和GDF 8都受到多种机制的严格调控。每个配体作为前体与 N-末端前结构域，其保持与成熟的非共价结合，保持信号传导组分 潜伏直到被Tolloid样蛋白酶激活。此外，细胞外拮抗剂如卵泡抑素和GASP 结合并阻断配体信号传导。我们认为GDF 11和GDF 8以多种活性存在于血清中 从潜伏形式到激活形式的状态。然而，研究不同的活动是如何 差异调节的状态是有限的。我们合理地解释说，更好地理解这些机制， 这将有助于理解GDF 11和GDF 8在人类生物学和衰老过程中的系统作用。 为了实现这一目标，我们将结合生物化学和分子方法， 体外和体内实验。我们的建议集中在三个具体目标上，我们将（1）测试 GDF 11和GDF 8存在于多种“活性”状态中，调节从潜伏状态的转变 （2）检验血清中“净”GDF 11/GDF 8活性随年龄降低的假设，和 (3)测试GDF 11信号传导及其调节/细胞外拮抗作用可以解耦的假设。 总的来说，这些目标将提供更好的理解细胞外调节的机制， GDF 11和GDF 8以及它们在老化过程中的潜在变化。此外，我们希望 产生新的GDF 11和GDF 8分子，可用作进一步探索机制的工具。 与GDF 11和衰老相关，也可用于在老年动物中恢复年轻的GDF 11水平。

Project Summary: Growth and Differentiation Factor 11 (GDF11) and GDF8 are two closely related molecules of the larger TGFβ superfamily. While GDF8 is well known for its role in the regulation of muscle mass, evidence is now emerging that implicates GDF11 as a factor that has beneficial effects on multiple biological systems. Both GDF11 and GDF8 are tightly regulated by multiple mechanisms. Each ligand is made as a precursor with an N-terminal prodomain that remains noncovalently bound to the mature, keeping the signaling component latent until activated by Tolloid-like proteases. In addition, extracellular antagonists such as Follistatin and GASP bind and block ligand signaling. We propose that GDF11 and GDF8 are present in the serum in multiple activity states ranging from a latent form to an activated form. However, studies that investigate how the different activity states are differentially regulated are limited. We rationalize that a better understanding of these mechanisms will facilitate efforts to understand the systemic role of GDF11 and GDF8 in human biology and the aging process. To achieve this objective, we will use a combination of biochemical and molecular approaches coupled with in vitro and in vivo experiments. Our proposal is centered on three specific aims where we will (1) test the hypothesis that GDF11 and GDF8 exists in multiple ‘activity’ states that regulate a transition from a latent state to an active state, (2) test the hypothesis that the ‘net’ GDF11/GDF8 activity in serum decreases with age, and (3) test the hypothesis that GDF11 signaling and its regulation/extracellular antagonism can be decoupled. Collectively, these aims will provide a better understanding of the mechanisms of extracellular regulation of GDF11 and GDF8 and how these potentially change during the aging process. Furthermore, we expect to produce novel GDF11 and GDF8 molecules that can be used as tools to further probe the mechanisms associated with GDF11 and aging, and can also be used to restore youthful levels of GDF11 in aged animals.