Autophagy Engagement and Hematopoietic Stem Cell Maintenance During Aging

衰老过程中的自噬参与和造血干细胞维持

基本信息

批准号：
9910584
负责人：
Paul Vincent Dellorusso
金额：
$ 4.51万
依托单位：
COLUMBIA UNIVERSITY HEALTH SCIENCES
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-01-01 至 2023-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9910584
关键词：
ATAC-seq Ablation Age Aging Anemia Architecture Asses Autophagocytosis Biogenesis Biology Blood Bone Marrow Bone Marrow Purging Cell Aging Cell Maintenance Cell Respiration Cell physiology Cells Chromatin Chronic Data Disease Elderly Epigenetic Process Exhibits Exposure to Fluorouracil Functional disorder Genes Genetic Genomics Glycolysis Goals Health Hematologic Neoplasms Hematology Hematopoiesis Hematopoietic Hematopoietic Stem Cell subsets Hematopoietic System Hematopoietic stem cells Homeostasis Immune Impairment In Vitro Inflammation Inflammatory Inflammatory Response Pathway Intervention Knockout Mice Knowledge Laboratories Lead Life Link Longevity Maintenance Mediating Mediator of activation protein Metabolic Metabolic Activation Metabolism Mitochondria Modeling Molecular Molecular and Cellular Biology Mus PGC-1 protein Pathology Pathway Analysis Pharmacology Phenocopy Physiological Play Production Publishing Rejuvenation Reporter Repression Research Respiration Role Signal Transduction Stimulus Stress System TNF gene Testing Therapeutic Tissues Transplantation Up-Regulation Validation Work age related anti aging base biological adaptation to stress cell age conditional knockout cytokine design differential expression experimental study fitness functional decline hematopoietic stem cell aging improved in vivo insight metabolic profile preservation prevent proteostasis regenerative replication stress response self-renewal small molecule transcriptome transcriptome sequencing transcriptomics

项目摘要

The hallmarks of an aging blood system, including chronic inflammatory disorders, anemia, and hematological malignancies, result in large part from the loss of hematopoietic stem cell (HSC) function. Age-associated loss of HSC function is strongly linked to metabolic deregulation, loss of epigenetic fidelity, and exposure to chronic inflammation in the bone marrow (BM) niche. Autophagy plays important roles in maintaining cellular fitness in the face of aging stress across several mammalian tissues. Our laboratory recently published that a subset of HSCs from aged mice had increased basal levels of autophagy flux (AThi oHSCs) relative to HSCs from young mice (yHSCs), maintained a quiescent metabolic state, and demonstrated improved regenerative potential. In contrast, most old HSCs that did not engage autophagy (ATlo oHSCs) were metabolically overactive and exhibited classical age-related functional decline. This project aims to elucidate the intrinsic molecular mediators and extrinsic signals that drive increased autophagy engagement and associated metabolic maintenance in a subset of old HSCs. Preliminary data was generated to characterize the molecular architecture of AThi and ATlo oHSCs vs. yHSCs, analyzing the chromatin accessibility landscape by ATAC-seq and the transcriptome by RNA-seq. ATAC-seq analyses indicated conserved epigenetic de-repression in both old HSC subsets at loci that are suggested to promote metabolic activation and inflammatory responses by pathway analysis. The similarity in chromatin profiles between AThi and ATlo oHSCs suggests a lack of engrained differences and, instead, points to an environmental driver of autophagy engagement in aging. In this context, transcriptome analyses reveal a strong metabolic activation signature unique to ATlo oHSCs. Supplementary validation narrowed the focus to the most differentially expressed gene in ATlo oHSCs, Ppargc1a, which encodes the master regulator of mitochondrial oxidative metabolism PGC-1. The first aim will determine if the increase in oxidative metabolism observed in ATlo oHSCs is driven by aberrant PGC-1 activity, the consequences of inducible genetic ablation of PGC-1 for steady state and stress hematopoiesis, and if PGC-1 can be targeted pharmacologically to restore the metabolic profile of oHSCs. Transcriptome analyses also identified a unique inflammation response signature in AThi oHSCs. In fact, preliminary validation showed that differential autophagy engagement could be modeled in yHSCs using an in vivo inflammatory TNF challenge. The second aim will investigate how inflammatory cytokine exposure drives autophagy engagement in a subset of old HSCs, as opposed to a default response resulting in metabolic activation, and determine if autophagy is required for a productive response to chronic inflammation in the aging BM niche. Together, these aims will dissect the relationship between autophagy engagement, inflammatory signaling, and metabolic activation in HSCs during aging. This work has exciting implications for elucidating the biology of HSC aging, which may lead to strategies to restore blood and immune homeostasis in the elderly.

血液系统老化的标志，包括慢性炎症性疾病、贫血和血液系统疾病恶性肿瘤，很大程度上是由于与年龄相关的造血干细胞（HSC）功能丧失所致。 HSC 功能的下降与代谢失调、表观遗传保真度丧失以及慢性暴露密切相关。骨髓 (BM) 生态位中的炎症在维持细胞健康方面发挥着重要作用。我们的实验室最近发表了一些哺乳动物组织面临的衰老压力。与年轻小鼠的 HSC 相比，老年小鼠的 HSC 的自噬通量 (AThi oHSC) 基础水平有所增加小鼠（yHSC）保持静态代谢状态，并表现出改善的再生潜力。相比之下，大多数不参与自噬的旧 HSC (ATlo oHSC) 代谢过度活跃，并且表现出经典的与年龄相关的功能衰退。该项目旨在阐明内在的分子功能衰退。驱动自噬参与和相关代谢增加的介质和外在信号生成了旧 HSC 子集中的初步数据来表征分子特征。 AThi 和 ATlo oHSC 与 yHSC 的架构，通过 ATAC-seq 分析染色质可及性景观 RNA-seq 的转录组分析表明，两者均存在保守的表观遗传去抑制。位点上的旧 HSC 子集被认为可以通过以下方式促进代谢激活和炎症反应： AThi 和 ATlo oHSC 之间染色质谱的相似性表明缺乏通路分析。根深蒂固的差异，相反，指出了自噬参与衰老的环境驱动因素。在此背景下，转录组分析揭示了 ATlo oHSC 特有的强大代谢激活特征。补充验证将焦点缩小到 ATlo oHSC 中差异最大的表达基因， Ppargc1a，编码线粒体氧化代谢 PGC-1 的主调节因子。将确定 ATlo oHSC 中观察到的氧化代谢增加是否由异常的 PGC-1 驱动活性，PGC-1α 的诱导性基因消融对稳态和应激造血的影响，以及 PGC-1 是否可以通过药理学来恢复 oHSC 的代谢特征。分析还发现了 AThi oHSC 中独特的炎症反应特征。事实上，初步验证。研究表明，可以使用体内炎症因子在 yHSC 中模拟不同的自噬参与 TNFα 挑战的第二个目标是研究炎症细胞因子暴露如何驱动自噬。参与旧 HSC 的子集，而不是导致代谢激活的默认反应，以及确定自噬是否是对老化 BM 生态位中慢性炎症的有效反应所必需的。这些目标将共同剖析自噬参与、炎症信号传导和这项工作对于阐明衰老过程中 HSC 的代谢激活具有令人兴奋的意义。 HSC 老化，这可能会导致恢复老年人血液和免疫稳态的策略。