Epigenetic and Cell Cycle Functions of Glucocorticoids in Erythropoietic Stress

糖皮质激素在红细胞生成应激中的表观遗传和细胞周期功能

基本信息

批准号：
8761895
负责人：
Merav Socolovsky
金额：
$ 36.18万
依托单位：
UNIV OF MASSACHUSETTS MED SCH WORCESTER
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-09-01 至 2019-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8761895
关键词：
Acceleration Adult Adverse effects Affect Anemia Antibodies Binding Blood Bone Density Bone Marrow Bone Marrow Transplantation CFU-E Cardiovascular Diseases Cell Cycle Cells Clinic Clinical Cyclin-Dependent Kinase Inhibitor DNA DNA Methylation DNA Methyltransferase DNA Modification Methylases DNA biosynthesis Data Development Diabetes Mellitus Diamond-Blackfan anemia Down-Regulation Dysmyelopoietic Syndromes Epigenetic Process Erythrocyte Transfusion Erythrocytes Erythroid Erythropoiesis Erythropoietin Fiber Generations Genes Genetic Genetic Transcription Glucocorticoid Receptor Glucocorticoids Health Hemorrhage Hormonal Hormones Hypoxia In Vitro Laboratories Malignant Neoplasms Mediating Mediator of activation protein Modification Molecular Mus Mutate Mutation Oxygen Pancytopenia Pharmaceutical Preparations Process Production Publishing Recovery Refractory Refractory anemias Relapse Replication Origin Resistance Risk Role S Phase SWI1 Science Signal Transduction Somatic Cell Stress Syndrome System TFRC gene Testing Tissues Transcriptional Activation Transferase Up-Regulation Work base biological adaptation to stress chemotherapy demethylation fetal gene induction genome-wide human disease improved in vivo mouse model mutant novel overexpression prevent progenitor promoter public health relevance receptor respiratory response self-renewal tumor

项目摘要

DESCRIPTION (provided by applicant): Glucocorticoids (GCs) are hormonal regulators of stress. They accelerate red blood cell production rate, an effect that is well established by mouse genetics, by in vitro erythropoiesis systems, and by human disease syndromes in which GCs are dysregulated. The use of GCs in the treatment of anemia is complicated, however, by their severe side effects, and is therefore limited to conditions where Erythropoietin (Epo) treatment is refractory or contraindicated, including Diamond Blackfan Anemia and other bone-marrow failure syndromes. The translational importance of GCs is apparent from their use in systems currently under development for the in-vitro generation of red blood cells for transfusion. Understanding the molecular action of GCs in erythroid progenitors could facilitate the development of novel erythropoiesis-stimulating agents that have fewer side-effects than GCs, and that improve the efficiency of generating red blood cells in vitro. Functionally, GCs increase erythropoietic rate by delaying the switch from self-renewal to differentiation in erythroid progenitors. The molecular mechanisms underlying this action are largely unknown. Based on our recently published work and on preliminary data, we propose a novel hypothesis of GC action that implicates the cell cycle S phase and DNA methylation as novel regulatory targets. We recently showed that both fetal and adult erythropoiesis entail genome-wide DNA demethylation, a unique global epigenetic modification in somatic cells (Shearstone et al., Science 2011). Global demethylation is tightly correlated with demethylation at erythroid gene promoters, and is a rate-limiting for their transcriptional activation. Further, global demethylatin is dependent on a marked change in S phase of the cell cycle, which becomes shorter and 50% faster with the switch from self-renewal to differentiation. The cyclin-dependent kinase inhibitor (CDKI) p57KIP2 is a key negative regulator of this switch. p57KIP2 is also a direct transcriptional target of GCs. Our preliminary data show that, in the presence of GCs, erythroid progenitors fail to downregulate p57KIP2, fail to accelerate S phase, and fail to undergo DNA demethylation, thereby delaying erythroid gene transcription. In this proposal, we investigate the hypothesis that high levels of GCs during erythropoietic stress inhibit the switch from self-renewal to differentiation by inducing p57KIP2, thereby inhibiting S phase acceleration, global DNA demethylation and erythroid gene induction. We will test this hypothesis in vivo using mouse models of erythropoietic stress and mice deleted or mutated for either p57KIP2, the GC receptor, or DNA methyl transferase 1 (Dnmt1), with the following three aims: 1) Determine the role of p57KIP2 in the GC-mediated erythropoietic stress response 2) Determine whether GCs prolong S phase in erythroid progenitors during stress 3) Determine whether GCs delay the onset of global DNA demethylation during stress. This work focuses on a unique epigenetic modification and has the potential to identify conceptually novel regulatory mechanisms, with translational implications for therapy of Epo-resistant anemia.

描述（由申请人提供）：糖皮质激素（GC）是压力激素调节剂。它们可以加速红细胞生成速度，这一效应已通过小鼠遗传学、体外红细胞生成系统以及 GC 失调的人类疾病综合征得到充分证实。然而，使用GC治疗贫血很复杂，因为它们有严重的副作用，因此仅限于促红细胞生成素（Epo）治疗难治或禁忌的情况，包括钻石黑扇贫血和其他骨髓衰竭综合征。 GC 的转化重要性从其在目前正在开发的用于输血的体外生成红细胞的系统中的应用中可见一斑。了解 GC 在红系祖细胞中的分子作用可以促进新型红细胞生成刺激剂的开发，这些药物的副作用比 GC 更少，并且可以提高体外生成红细胞的效率。从功能上讲，GC 通过延迟红系祖细胞从自我更新到分化的转变来增加红细胞生成率。这种作用背后的分子机制很大程度上是未知的。基于我们最近发表的工作和初步数据，我们提出了 GC 作用的新假设，该假设暗示细胞周期 S 期和 DNA 甲基化是新的调控目标。我们最近表明，胎儿和成人红细胞生成都需要全基因组 DNA 去甲基化，这是体细胞中独特的全局表观遗传修饰（Shearstone 等人，Science 2011）。整体去甲基化与红细胞基因启动子的去甲基化密切相关，并且是其转录激活的速率限制。此外，整体去甲基化依赖于细胞周期 S 期的显着变化，随着从自我更新到分化的转变，S 期变得更短且速度加快 50%。细胞周期蛋白依赖性激酶抑制剂 (CDKI) p57KIP2 是该开关的关键负调节因子。 p57KIP2 也是 GC 的直接转录靶标。我们的初步数据表明，在GC存在的情况下，红系祖细胞无法下调p57KIP2，无法加速S期，也无法进行DNA去甲基化，从而延迟红系基因转录。在本提案中，我们研究了这样的假设：红细胞生成应激期间高水平的GC通过诱导p57KIP2抑制从自我更新到分化的转变，从而抑制S期加速、整体DNA去甲基化和红细胞基因诱导。我们将使用红细胞生成应激小鼠模型和 p57KIP2、GC 受体或 DNA 甲基转移酶 1 (Dnmt1) 缺失或突变的小鼠在体内测试这一假设，目的如下：1) 确定 p57KIP2 在GC 介导的红细胞生成应激反应 2) 确定 GC 是否在应激期间延长红细胞祖细胞的 S 期 3) 确定 GC 是否延迟应激期间全球 DNA 去甲基化的发生。这项工作重点关注独特的表观遗传修饰，并有可能确定概念上新颖的调节机制，对 Epo 抵抗性贫血的治疗具有转化意义。