Understanding the Mechanisms of Age-Dependent Decline of Intestinal Stem Cell Function

7.项目摘要/摘要 许多哺乳动物组织具有再生能力，并依赖于组织特异性体细胞进行更新。衰老领域的一个基本问题是，随着年龄的增长，躯体干细胞是否存在功能衰退，以及我们是否可以通过饮食或治疗干预来减缓或逆转成人干细胞功能随年龄增长而下降的趋势。在这个建议中，我们试图用哺乳动物的肠道来回答这些问题，哺乳动物的肠道经历了年龄相关的功能衰退，并通过 Lgr5肠道干细胞池(ISC)。在初步研究中，我们发现：1)陈年的墓穴既有 ISCs的功能和频率降低；2)短期饥饿增加了老化隐窝形成有机体的能力，并在ISCs中诱导了一个强大的Peroxisome增殖物激活受体Delta程序；3)我们可以用高度特异的PPARδ激动剂GW501516来总结禁食效应。 在目标1中，我们将利用小鼠遗传学来确定PPARδ信号通路在介导肠道干细胞禁食效应中的必要性和充分性。在目标2中，我们将利用LC-MS和海马代谢分析来确定老年ICSS患者的线粒体代谢是否增强。我们还将确定CPT1a是否在禁食状态下调节增强的ISC功能。在独立阶段和Aim3中，我将通过表征Gasdermin C家族基因在运输放大祖细胞(TA)中的功能和调节来研究饮食、衰老和微生物区系之间的相互作用。

7. Project Summary/ Abstract A number of mammalian tissues possess regenerative capacity and rely on tissue-specific somatic stem cells cells for renewal. A fundamental question in the aging field is whether there is a functional decline in somatic stem cells with age and whether we can use dietary or therapeutic interventions to decelerate or reverse age-dependent decline of adult stem cell function. In this proposal, we seek to answer these questions using the mammalian intestine, which undergoes age-dependent functional decline and regenerates through pools of Lgr5+ intestinal stem cells (ISC). In preliminary studies we found that: 1) aged crypts have both decreased function and frequency of ISCs; 2) short-term starvation enhanced the capacity of organoid formation from aged crypts and induced strongly a Peroxisome Proliferator-Activated Receptor Delta program in the ISCs; 3) we can recapitulate fasting effects with the highly specific PPARδ agonist GW501516. In Aim 1 we will use mouse genetics to determine the necessity and sufficiency of PPARδ signaling in mediating the effects of fasting in intestinal stem cells. In Aim 2 we will utilize LC-MS and Seahorse metabolic assays to determine if mitochondrial metabolism is augmented in aged ICSs. We will also determine if CPT1A mediates augmented ISC function in the fasted state. In the independent phase and Aim3, I will examine the interplay of diet, aging and microbiota by characterizing the function and regulation of the Gasdermin C family of genes in transit-amplifying progenitor (TA) cells.