Effect of aging on enteric neural stem cells is dependent on the PI3K/Akt pathway

描述(由申请人提供)：衰老导致胃肠功能的生理变化，导致许多与年龄相关的疾病。这些疾病在医疗成本和生活质量方面都造成了巨大的负担。在增龄的ENS中，运动神经元偏爱抑制性(氮能)神经元和兴奋性(胆碱能)神经元的比例发生了变化，这被认为在这些疾病中起着重要作用。虽然许多人推测氧化应激导致的磨损是这种紊乱的原因，但衰老对ENS影响的机制(S)却知之甚少。老龄化越来越被视为一个高度受监管的过程。在中枢神经系统(CNS)中，有证据表明，功能性神经干细胞的丧失导致了衰老过程和认知能力的下降。干细胞功能的类似下降也可能是导致ENS年龄相关变化的原因之一。这项拟议研究的目的是研究衰老对ENS中的一群神经干细胞的影响，称为肠神经干细胞(ENSCs)。这位候选人最近的研究表明，老年小鼠的ENSCs分化为比年轻小鼠的ENSC表达更高水平的nNOS的细胞，nNOS是氮能神经元的标志，这种差异可能是由于老年小鼠的ENs中发现了更高的基础Akt活性。候选人假设，ENS中与年龄相关的障碍是由于PI3K/Akt/FOXO通路介导的ENSC功能改变所致。这位候选人计划通过两种方式解决这一假设。首先，候选人将描述通过流式细胞术从老年和幼年小鼠分离的ENSCs的内在差异。具体地说，候选人将使用体外和体内(移植)方法进行实验，以评估在增殖、凋亡、衰老和分化方面的差异。第二，候选人将研究PI3K/Akt/FOX03信号通路在ENSCs衰老过程中的作用。具体地说，候选人将评估PI3K/Akt/FOX03途径在老年和年轻ENSCs中的基本活性，并评估通过刺激和抑制调节这一途径如何影响它们的表型。这些研究将加深我们对ENS中衰老的理解，并为未来的研究奠定基础，包括：1)确定热量限制是否逆转了ENSC功能的年龄相关变化；2)评估人类ENSC是否也发生了类似的年龄相关变化；3)阐明了逆转衰老对ENSC影响的分子靶点。这位候选人认为，斯坦福大学是一所世界级的大学，在干细胞和衰老研究方面具有特别的优势，是他发展学术生涯的理想环境。由于Anne Brunet博士是他的高级合作者，斯坦福大学丰富的资源，以及广泛的教学方法来拓宽他的科学知识和技术技能，这位候选人处于独特的地位，可以追求他成为一名独立调查人员的目标。

DESCRIPTION (provided by applicant): Aging causes physiologic changes in gastrointestinal intestinal function that contribute to many age-related disorders. These disorders cause a significant burden both in healthcare costs and quality of life. A shift in the ratio of motor neurons favoring inhibitory (nitrergic) neurons over excitatory (cholinergic) neurons has been observed in the ENS with aging and is thought to play an important role in these disorders. While many have speculated that 'wear and tear' resulting from oxidative stress is the cause for this disturbance, the mechanism(s) underlying the effects of aging on the ENS are poorly understood. Aging is increasingly viewed as a highly regulated process. In the central nervous system (CNS), there is evidence that loss of functional neural stem cells contributes to the aging process and cognitive decline. Similar decline in stem cell function may also be contributing to age-related changes in the ENS. The goal of the proposed research is to study the effect of aging on a population of neural stem cells in the ENS, termed enteric neural stem cells (ENSCs). Recent work by the candidate suggests that ENSCs from old mice differentiate into cells that express higher levels of nNOS, a marker of nitrergic neurons, than those from young mice and that this difference may be due to higher basal Akt activity found in ENS from old mice. The candidate hypothesizes that age-related disturbances in the ENS are due to alterations in ENSC function mediated by the PI3K/Akt/FOXO pathway. The candidate plans to address this hypothesis in two ways. First, the candidate will delineate intrinsic differences in ENSCs isolated by flow cytometry from old and young mice. Specifically, the candidate will perform experiments to evaluate for differences with regards to proliferation, apoptosis, senescence, and differentiation using both in vitro and in vivo (transplantation) approaches. Second, the candidate will investigate the role of the PI3K/Akt/FOXO3 signaling pathway in the aging process in ENSCs. Specifically, the candidate will assess the basal activity of the PI3K/Akt/FOXO3 pathway in old and young ENSCs and evaluate how modulating this pathway through stimulation and inhibition affects their phenotypes. These studies will enhance our understanding of aging in the ENS and lay the foundation for future research including: 1) determining whether caloric-restriction reverses age-related changes to ENSC function, 2) evaluating whether similar age-related changes occur in human ENSCs, and 3) elucidating molecular targets that will reverse the effect of aging on ENSCs. The candidate believes that Stanford, a world-class institution with particular strength in stem cell and aging research, is th ideal environment for developing his academic career. With Dr. Anne Brunet as his senior collaborator, the abundant resources available at Stanford, and a wide range of didactics to broaden his scientific knowledge and technical skills, the candidate is uniquely placed to pursue his goal of becoming an independent investigator.