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

7.项目概要/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干细胞进行更新。衰老领域的一个基本问题是，随着年龄的增长，体干细胞的功能是否会下降，以及我们是否可以使用饮食或治疗干预来减缓或逆转成体干细胞功能的年龄依赖性下降。在这个提议中，我们试图用哺乳动物的肠道来回答这些问题，它经历了年龄依赖性的功能衰退，并通过 Lgr 5+肠干细胞（ISC）池。在初步研究中，我们发现：1）老年人的隐窝都有 降低了ISC的功能和频率; 2）短期饥饿增强了老化隐窝形成类器官的能力，并强烈诱导了ISC中的过氧化物酶体激活受体δ程序; 3）我们可以用高度特异性的PPARδ激动剂GW 501516重现禁食效应。 在目的1中，我们将使用小鼠遗传学来确定PPARδ信号传导在肠干细胞中介导禁食效应的必要性和充分性。在目标2中，我们将利用LC-MS和Seahorse代谢测定来确定老年ICS中线粒体代谢是否增加。我们还将确定CPT 1A是否在禁食状态下介导增强的ISC功能。在独立阶段和目标3中，我将通过表征Gasdermin C家族基因在transit-amplifying progenitor（TA）细胞中的功能和调控来研究饮食，衰老和微生物群的相互作用。

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.