Mechanisms of telomere-induced disease: Role of intestinal malabsorption, barrier dysfunction and dsybiosis.

端粒诱发疾病的机制：肠道吸收不良、屏障功能障碍和失调的作用。

基本信息

批准号：
10632001
负责人：
NOAH Freeman SHROYER
金额：
$ 64.89万
依托单位：
BAYLOR COLLEGE OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-06-01 至 2027-03-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10632001
关键词：
Acceleration Address Age Apoptosis Atrophic Automobile Driving Biology Biopsy Caco-2 Cells Cell Differentiation process Cell Line Cell Lineage Cells Colitis Consumption Crohn&apos s disease DNA Damage Defect Development Diet Disease Elderly Enterocytes Enzymes Epithelium Exposure to Fructokinases Fructose Functional disorder Generations Genes Genetic HNF4A gene Human Impairment Inflammation Inflammatory Bowel Diseases Intestinal Diseases Intestines Knockout Mice Knowledge Length Maintenance Malabsorption Syndromes Malignant Neoplasms Measures Mediating Metabolic stress Mitochondria Mus Mutation Organoids Pathogenesis Pathogenicity Pathology Patients Phenotype Play Predisposition Prevention Prognostic Marker Proteins Proteomics Relapse Repression Research Risk Role Scanning Electron Microscopy Small Intestines Source Structure Supplementation System Systemic disease TP53 gene Telomerase Telomere Shortening Testing Therapeutic Time Tissues Toxic effect Transmission Electron Microscopy Ulcerative Colitis absorption age related aged cellular microvillus coping design gut inflammation improved induced pluripotent stem cell intestinal barrier mitochondrial dysfunction mortality mouse model multilevel analysis normal aging novel patient population preservation prevent response risk stratification senescence stem stem cell self renewal stem cells sugar telomere transcription factor transcriptome sequencing treatment stratification

项目摘要

Although it is increasingly recognized that the interaction of the diet and host specific genetic factors in the gut play an important role in intestinal and systemic disease, our understanding of in this emerging field is still limited and this represents an important knowledge gap. Here we propose to bridge this gap by advancing our knowledge how telomere shortening in the gut impacts the maturation of enterocytes, the terminally differentiated cells that are essential for barrier maintenance and absorption. Telomeres are important for the regeneration of stem cell-dependent tissues such as the intestine. Telomere shortening occurs during normal aging and is accelerated in patients with mutations in telomerase or in high cell turnover conditions such as ulcerative colitis and Crohn’s disease. Telomere shortening causes several pathologies in the intestine including atrophy, inflammation, and progression of colitis to cancer in patients and all these pathologies are faithfully recapitulated in telomerase knockout mice (TKO). Mechanistically, it is believed that short telomeres drive these pathologies through continuous apoptosis-mediated depletion of intestinal stem cells. Beyond stem cell- depletion, other pathogenic mechanisms are not known. In particular, it is not known whether telomere shortening compromises differentiated cell lineages in the gut, of which enterocytes represent the vast majority. Here we have found that telomere shortening impairs the maturation towards the enterocyte lineage leading to the generation of immature and functionally compromised enterocytes. This is supported by a multi- level analysis including RNAseq, proteomics, transmission and scanning electron microscopy demonstrating that the expression of digestive enzymes, transporters and structural components of microvilli are repressed in the proximal intestine in TKO mice. Importantly, preliminary studies indicate that this enterocyte compromise is preserved in human enterocytes with short telomeres. Mechanistically, deletion of p53 in TKO epithelium rescues enterocyte defects. Furthermore, these enterocytes are characterized by mitochondrial dysfunction and have low ATP levels. When exposed to a fructose-rich diet, they show pronounced propensity to steep decline in ATP levels and subsequent apoptosis, which exacerbates the barrier defect and malabsorption. Here we propose to establish the mechanisms through which p53 causes differentiation defects (Aim 1), establish whether the low ATP levels are the driving source for fructose toxicity by increasing ATP levels either through inactivation of the ATP depleting enzyme fructokinase or improving mitochondrial function through NAD supplementation. In Aim 3 we establish the relevance of short telomeres in causing enterocyte defects in humans using cell lines, organoids and enteroids with various telomere length.

尽管越来越多地认识到，饮食和肠道中特定遗传因素的相互作用在肠道和全身性疾病中起着重要作用，但我们对这个新兴领域的理解仍然有限，这代表了一个重要的知识差距。在这里，我们建议通过促进肠道中的端粒缩短如何影响肠上皮细胞的成熟，这是对屏障维持和吸收至关重要的末端分化细胞，以弥合差距。端粒对于干细胞依赖性时机（例如肠）的再生很重要。端粒缩短发生在正常衰老期间，并且在远程酶突变或高细胞周转疾病（如溃疡性结肠炎和克罗恩病）中加速了。端粒缩短在肠道中引起多种病理，包括患者萎缩，感染和结肠炎向癌症的萎缩，所有这些病理都忠实地概括为端粒酶基因敲除小鼠（TKO）。从机械上讲，据信，短端粒通过连续凋亡介导的肠道干细胞的部署来驱动这些病理。除了干细胞止动物之外，其他病原机制尚不清楚。特别是，尚不清楚端粒缩短是否会损害肠道中的分化细胞谱系，其中肠细胞代表了绝大多数。在这里，我们发现端粒缩短会损害肠细胞谱系的成熟，从而导致未成熟和功能损害的肠细胞产生。这得到了多层次分析的支持，包括RNASEQ，蛋白质组学，透射和扫描电子显微镜，表明在TKO小鼠的近端肠道中反映了消化酶，转运蛋白和结构成分的表达。重要的是，初步研究表明，这种肠细胞妥协保留在端粒短的人肠细胞中。从机械上讲，TKO上皮中p53的缺失反应肠细胞缺陷。此外，这些肠细胞的特征是线粒体功能障碍，并且ATP水平较低。当暴露于果糖富含果糖的饮食时，它们显示出明显的ATP水平急剧下降和随后的细胞凋亡的倾向，这加剧了屏障缺陷和吸收不良。在这里，我们建议建立p53导致分化缺陷的机制（AIM 1），确定低ATP水平是通过增加ATP消耗酶消耗酶果糖酶或通过NAD补充来提高ATP消耗酶果果因酶或改善线粒体功能而增加ATP水平的驱动来源。在AIM 3中，我们建立了短端粒在使用各种端粒长度的细胞系，类器官和肠托体中引起人类肠细胞缺陷的相关性。