Regulation of GDF11 by extracellular mechanisms

项目摘要：生长分化因子11(GDF11)和GDF8是两个密切相关的分子 更大的转化生长因子β超家族的成员。虽然GDF8在调节肌肉质量方面的作用广为人知，但有证据表明 GDF11是一种对多种生物系统有有益影响的因子。 GDF11和GDF8都受到多种机制的严格调控。每一种配体都是作为前体与 N-末端前结构域，保持与成熟蛋白的非共价结合，保持信号成分 潜伏直到被类Tolloid蛋白酶激活。此外，细胞外拮抗剂，如Follistatin和GAP 结合和阻断配体信号。我们认为GDF11和GDF8在血清中以多种活性存在 状态从潜在形式到激活形式不等。然而，研究不同活动如何 各州受到不同的监管是有限的。我们认为更好地理解这些机制是合理的 将有助于努力了解GDF11和GDF8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，我们将使用生化和分子方法相结合的方法，并在 体外和体内实验。我们的建议以三个具体目标为中心，我们将在其中(1)测试 假设GDF11和GDF8存在于调节从潜伏状态转变的多个“活动”状态 处于活动状态，(2)检验血清中GDF11/GDF8活性随年龄增长而降低的假设，以及 (3)验证GDF11信号及其调控/细胞外拮抗可以解偶联的假设。 总的来说，这些目标将使我们更好地理解细胞外调节的机制。 GDF11和GDF8以及它们在老化过程中的潜在变化。此外，我们预计将 产生新的GDF11和GDF8分子，可用作进一步探索机制的工具 与GDF11和衰老有关，也可用于恢复老年动物年轻时的GDF11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.