Molecular signature of parabiosis

项目摘要 衰老是世界范围内疾病和死亡的最大原因， 因此，生物衰老过程具有同时预防多种慢性疾病的潜力， 癌症、心脏病、痴呆症和糖尿病。几十年的研究揭示了 衰老，如线粒体功能障碍、炎症和蛋白质稳态丧失，针对这些特征的治疗 在动物模型中只引起了适度的恢复。这可能部分是因为大多数衰老研究都有 只集中在一个或几个器官或细胞类型，几乎没有时间分辨率，限制了我们的能力， 解释老化如何以及何时影响这些相互关联的系统。然而，最近，我们试图 这样一个衰老的系统性特征。使用批量RNA测序（RNA-seq）和单细胞RNA- 在整个生命周期中对数十种小鼠器官和细胞类型进行scRNA-seq测序（称为Tabula Muris Senis），我们发现了整个身体的全球性和特定的衰老特征。但仍不清楚是如何， 或者，如果，再生范式影响这些全球老化途径，或者更确切地说，煽动新生的生化 程序.因此，新疗法的合理设计具有挑战性。 一种在器官系统中获得有益效果的恢复方法是异时的 联体共生，即一只年轻的和年老的老鼠共享一个共同的循环系统。像认知，肌肉 强度和骨修复都显示出通过暴露于年轻血液的功能改善。异种共生 研究主要集中在与年龄有关的循环蛋白质的变化， 以介导至少一些观察到的效应。然而，这种个别因素尚未实现稳健 整个身体的再生，可能部分是由于对共生效应的不完全理解 在不同的器官和细胞上使用我们新创建的Tabula Muris Senis数据来表示正常老化， 研究了联体共生后3种组织中scRNA-seq的变化：性腺和肠系膜脂肪组织， 其经历与年龄相关的基因表达变化先于其他器官和肝脏，因为肝细胞是其中之一。 第一个观察到的受益于暴露于年轻的循环系统的细胞类型。有趣的是，个人 细胞类型在它们对联体共生的反应中变化很大，来自所有3种组织的血管内皮细胞显示出 与正常衰老基因一致的显著转录组学变化。 我们希望通过将该分析扩展到9种组织的scRNA-seq和21种组织的bulk RNA-seq， 组织，我们可以发现签名，这将作为识别小分子的基础，能够强大的 恢复活力和延长健康寿命。由于手术密集的联体共生受到细胞运输的干扰， 同时暴露于年轻人和老年人的循环因素，我们进一步建议比较联体共生 这些签名来自年轻的血浆转移，从而揭示了具体的返老还童方面 对血浆因子的改变敏感。与我们早期的数据集类似，所有数据都将公开提供。

PROJECT SUMMARY Aging is the single greatest cause of disease and death worldwide, and rejuvenating the body by targeting biological aging processes therefore holds potential to simultaneously prevent multiple chronic diseases like cancer, heart disease, dementia, and diabetes. While decades of research has unveiled common hallmarks of aging, like mitochondrial dysfunction, inflammation, and loss of proteostasis, therapies targeting these hallmarks have elicited only modest rejuvenation in animal models. This may be in part because most aging studies have focused on only one or a few organs or cell types, with little to no temporal resolution, limiting our ability to interpret how and when aging impacts these interconnected systems. Recently, however, we have attempted such a systematic characterization of aging. Using bulk RNA-sequencing (RNA-seq) and single-cell RNA- sequencing (scRNA-seq) on dozens of mouse organs and cell types across the lifespan (termed Tabula Muris Senis), we discovered global and specific aging signatures throughout the body. But it remains unknown how, or if, rejuvenation paradigms affect these global aging pathways, or rather instigate nascent biochemical programs. The rational design of new therapeutics is therefore challenging. One method of rejuvenation which has garnered beneficial effects across organ systems is heterochronic parabiosis, in which a young and old mouse share a common circulation. Phenotypes like cognition, muscle strength, and bone repair have all shown functional improvement through exposure to young blood. Parabiosis research has largely focused on age-related changes to circulating proteins, and several have been determined to mediate at least some of the observed effects. However, such individual factors have yet to achieve robust rejuvenation throughout the body, likely in part due to an incomplete understanding of the effects of parabiosis on disparate organs and cells. Using our newly created Tabula Muris Senis data to represent normal aging, we investigated scRNA-seq changes in 3 tissues following parabiosis: gonadal and mesenteric adipose tissues, which undergo age-related gene expression changes prior to other organs, and liver, as hepatocytes were one of the first cell types observed to benefit from exposure to a young circulatory system. Interestingly, individual cell types vary greatly in their response to parabiosis, with vascular endothelial cells from all 3 tissues showing prominent transcriptomic changes consistent with normal aging genes. It is our hope that by expanding this analysis to scRNA-seq of 9 tissues, and to bulk RNA-seq of 21 tissues, we can discover signatures that will serve as the basis for identifying small molecules capable of robust rejuvenation and healthspan extension. As surgically intensive parabiosis is confounded by cell trafficking and simultaneous exposure to young and aged circulating factors, we further propose to compare parabiosis signatures to those derived from young plasma transfer, thereby uncovering aspects of rejuvenation specifically sensitive to alterations in plasma factors. Similar to our earlier datasets, all data will be made publically available.