Role of Sirtuins in mediating telomere and p53-dependent aging and disease

Sirtuins 在介导端粒和 p53 依赖性衰老和疾病中的作用

基本信息

批准号：
9226024
负责人：
Ergun Sahin
金额：
$ 32.49万
依托单位：
BAYLOR COLLEGE OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-04-01 至 2020-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9226024
关键词：
Acetylation Address Aging Applications Grants Binding Biogenesis Biological Assay Biology Cell Aging Cell Line Chemicals Cirrhosis Computer Analysis Development Disease Down-Regulation Enzymes Functional disorder Genetic Transcription Health Hepatocyte Hyperactive behavior Impairment In Vitro Individual Intervention Knockout Mice Lead Link Liver Liver Cirrhosis Liver Failure Liver diseases Measures Mediating Metabolic Metabolism MicroRNAs Mitochondria Mus Mutant Strains Mice Mutation Nicotinamide Mononucleotide Pathogenesis Pathogenicity Pathway interactions Patients Premature aging syndrome Process Repression Research Role SIRT1 gene Series Sirtuins TP53 gene Telomerase Telomere Shortening Testing Therapeutic Intervention Tissues Transgenic Mice Translational Repression Translations Up-Regulation Wild Type Mouse age related aged base design experimental study genetic approach improved in vivo inhibitor/antagonist insight liver development liver function loss of function mimetics mouse model nanoparticle normal aging overexpression oxidation patient subsets prevent public health relevance restoration senescence telomere transcriptome sequencing translational impact

项目摘要

DESCRIPTION (provided by applicant): Telomere shortening causes liver cirrhosis in a subset of patients with telomerase mutations and predisposes to the development of liver cirrhosis and liver failure in acquired conditions. A major gap in the telomere field is our poor understanding of the mechanisms that are activated by short telomeres and drive the disease process. Consequently, no therapeutic interventions exist currently to prevent telomere-related liver disease due to an insufficient understanding how telomere shortening compromises cellular health. We have recently discovered that telomere shortening in telomerase knockout mice (TKO) impacts cellular metabolism in part through a p53-dependent down-regulation of PGC1a/ß, co-activators that regulate mitochondrial biogenesis/function. This leads to a decrease in mitochondrial numbers and function. However, whether telomere-mediated p53 activation leads to metabolic changes during normal aging, the precise pathways by which p53 impacts metabolism, and the relevance of these metabolic changes for the pathogenesis of telomere-related diseases such as liver cirrhosis remains to be defined. In this grant proposal, we address these critical questions experimentally through a series in experiments in the liver. The proposal is based on our recent observation that TKO and old wild-type mice liver tissues have reduced levels of all seven Sirtuins, a class of enzymes highly implicated in diseases. How these enzymes are regulated is not known, however, their down-regulation is well understood to lead to many disorders. In TKO mice, the down-regulation of Sirtuins is partially p53-dependent. Furthermore, our preliminary studies indicate that p53 regulates the mitochondrial Sirtuins (Sirtuin 3, 4, 5) in a PGC1a-dependent manner at the transcriptional level, and the non- mitochondrial Sirtuins (Sirtuin 1, 2, 6, 7) through miRNAs at the translational level. Our hypothesis is that telomere shortening-induced p53 down-regulates Sirtuins and that this Sirtuin repression contributes to telomere-dependent liver disease. We will test this hypothesis through three approaches: First, to determine the causal relationship between p53 and Sirtuin expression during aging, we will delete p53 in liver tissue of old mice, use a mouse model of premature aging due to hyper-active p53 (p53+/m mutant mice) and then assay changes in Sirtuin levels and function (Aim 1). Second, we will focus on how altered p53 activity impacts the translationally regulated Sirtuins. We have identified four p53-dependent miRNAs in liver tissue of TKO mice that bind to Sirtuins. We will use gain/loss-of-function studies to test whether these candidate miRNAs repress individual non-mitochondrial Sirtuins and determine the consequence of their deletion for liver function (Aim 2). Finally, to examine the pathogenic impact of Sirtuin down-regulation on liver cirrhosis, we will overexpress Sirt1 and determine whether restoration of Sirt1 is sufficient to improve liver cirrhosis induced by short telomeres. Together, these experiments will provide new insights in how telomere shortening impacts metabolism and predisposes to liver disease.

描述（由申请人提供）：端粒缩短会导致部分端粒酶突变患者发生肝硬化，并在后天性疾病中易发生肝硬化和肝功能衰竭，端粒领域的一个主要差距是我们对端粒酶突变机制的了解不足。端粒被短端粒激活并驱动疾病过程，但由于对端粒如何发挥作用的了解不够，目前尚无治疗干预措施可以预防端粒相关的肝脏疾病。我们最近发现，端粒酶敲除小鼠 (TKO) 中的端粒缩短部分通过 PGC1a/ß（调节线粒体生物发生/功能的共激活剂）的 p53 依赖性下调来影响细胞代谢。然而，端粒介导的 p53 激活是否会导致正常衰老过程中的代谢变化、p53 影响代谢的精确途径以及这些代谢的相关性。端粒相关疾病（例如肝硬化）的发病机制的变化仍有待确定。在这项拨款提案中，我们通过一系列肝脏实验来解决这些关键问题。该提案基于我们最近对 TKO 和老年的观察。野生型小鼠肝脏组织中所有七种 Sirtuins 的水平均降低，这是一类与疾病密切相关的酶。这些酶的调节方式尚不清楚，但众所周知，它们的下调会导致 TKO 小鼠的许多疾病。 , Sirtuins 的下调部分依赖于 p53。此外，我们的初步研究表明，p53 在转录水平上以 PGC1a 依赖性方式调节线粒体 Sirtuins（Sirtuin 3、4、5），以及非线粒体 Sirtuins（Sirtuins）。 Sirtuin 1, 2, 6, 7) 在翻译水平上通过 miRNA 我们的假设是端粒缩短诱导 p53。 Sirtuins 下调，而这种 Sirtuin 抑制会导致端粒依赖性肝病。我们将通过三种方法检验这一假设：首先，为了确定衰老过程中 p53 和 Sirtuin 表达之间的因果关系，我们将删除旧肝组织中的 p53。小鼠，使用由于 p53 过度活跃而导致过早衰老的小鼠模型（p53+/m 突变小鼠），然后检测 Sirtuin 水平和功能的变化（目标 1）。 p53 活性的改变如何影响翻译调节的 Sirtuins 我们已经在 TKO 小鼠的肝组织中鉴定出四种与 Sirtuins 结合的 p53 依赖性 miRNA。最后，为了检查 Sirtuin 下调对肝硬化的致病影响，我们将过度表达。 Sirt1 并确定 Sirt1 的恢复是否足以改善短端粒引起的肝硬化，这些实验将为端粒缩短如何影响新陈代谢和诱发肝病提供新的见解。