Supplement to existing R01 to increase diversity in health-related science

对现有 R01 的补充，以增加健康相关科学的多样性

• 批准号: 9577081
• 负责人: Ergun Sahin
• 金额: $ 1.67万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 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/9577081
• 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; 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; Metabolic dysfunction; Metabolism; MicroRNAs; Mitochondria; Mus; Mutant Strains Mice; Mutation; Nicotinamide Mononucleotide; Pathogenesis; Pathogenicity; Pathway interactions; Patients; Premature aging syndrome; Process; Repression; Research; Role; SIRT1 gene; Science; 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

 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）：端粒缩短导致端粒酶突变患者亚组的肝硬化，并易于在获得性条件下发展为肝硬化和肝功能衰竭。端粒领域的一个主要空白是我们对短端粒激活并驱动疾病过程的机制的理解不足。因此，由于对端粒缩短如何损害细胞健康的理解不足，目前没有治疗干预措施来预防端粒相关的肝脏疾病。我们最近发现，端粒缩短端粒酶敲除小鼠（TKO）影响细胞代谢的一部分，通过p53依赖性下调PGC 1a/PGC 1b，共激活剂，调节线粒体生物发生/功能。这导致线粒体数量和功能的减少。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影响代谢的确切途径，以及这些代谢变化与端粒相关疾病（如肝硬化）发病机制的相关性仍有待确定。在这项拨款申请中，我们通过一系列肝脏实验来解决这些关键问题。该建议是基于我们最近的观察，即TKO和老野生型小鼠肝组织中所有七种Sirtuins的水平都有所降低，这是一类与疾病密切相关的酶。这些酶是如何调节的尚不清楚，然而，它们的下调被充分理解为导致许多疾病。在TKO小鼠中，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PGC 1a依赖的方式调节线粒体Sirtuins（Sirtuin 3，4，5），并在翻译水平上通过miRNA调节非线粒体Sirtuins（Sirtuin 1，2，6，7）。我们的假设是，端粒缩短诱导的p53下调Sirtuins，这种Sirtuin抑制有助于端粒依赖性肝病。我们将通过三种方法测试这一假设：首先，为了确定衰老过程中p53和Sirtuin表达之间的因果关系，我们将删除老年小鼠肝组织中的p53，使用由于过度活跃的p53（p53+/m突变小鼠）而导致过早衰老的小鼠模型，然后测定Sirtuin水平和功能的变化（目的1）。第二，我们将集中在如何改变p53活性影响的调节Sirtuins。我们已经在TKO小鼠的肝组织中鉴定了四种与Sirtuins结合的p53依赖性miRNA。我们将使用功能获得/丧失研究来测试这些候选miRNA是否抑制个体非线粒体Sirtuins，并确定其缺失对肝功能的后果（目的2）。最后，为了研究Sirtuin下调对肝硬化的致病影响，我们将过表达Sirt 1，并确定Sirt 1的恢复是否足以改善短端粒诱导的肝硬化。总之，这些实验将为端粒缩短如何影响代谢和易患肝病提供新的见解。