Age-Related Kynurenine Accumulation Impairs miRNA and Hdac Epigenetic Regulation of the SDF-1 Axis Resulting in Bone Loss

与年龄相关的犬尿氨酸积累损害 SDF-1 轴的 miRNA 和 Hdac 表观遗传调节，导致骨质流失

• 批准号: 10216949
• 负责人: WILLIAM D HILL
• 金额: $ 50.12万
• 依托单位: MEDICAL UNIVERSITY OF SOUTH CAROLINA
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-15 至 2024-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10216949
• 关键词: Affect; Age; Age-Related Bone Loss; Aging; Amino Acids; Aryl Hydrocarbon Receptor; Bone Marrow; Bone Marrow Stem Cell; Bone Resorption; CXCL12 gene; CXCR4 Receptors; Cell Lineage; Cell Survival; Cell physiology; Cells; Data; Disease; Epigenetic Process; Extracellular Matrix; Family; Fatty acid glycerol esters; Functional disorder; Generations; Genes; Goals; Grant; HDAC3 gene; Homeostasis; Human; Immune system; Impairment; Inflammation; Intervention; Kynurenine; Laboratories; Lipids; Marrow; Mediating; Mediator of activation protein; Mesenchymal; Methods; MicroRNAs; Molecular; Mus; Musculoskeletal System; Obesity; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis; Oxides; Pathology; Pathway interactions; Pharmacological Treatment; Pharmacology; Population; Reactive Oxygen Species; Regulator Genes; Regulatory Pathway; Role; Signal Pathway; Signal Transduction; Stromal Cell-Derived Factor 1; Stromal Cells; Support Groups; System; Testing; Tryptophan; Tryptophan 2,3 Dioxygenase; Up-Regulation; Work; age related; base; bone; bone loss; bone mass; bone turnover; cytokine; enzyme activity; epigenetic regulation; genetic approach; genetic manipulation; impaired driving performance; in vitro testing; in vivo; mimetics; new therapeutic target; novel; novel therapeutics; osteogenic; osteoprogenitor cell; oxidation; prevent; progenitor; programs; skeletal tissue; stem; stem cells

The mechanisms involved in aging-related osteoporosis remain poorly defined, however, recent studies from our group, and others, suggest that it is a stem cell disease. We have been studying the role of the cytokine SDF-1 (CXCL12) and Hdac3 in bone marrow mesenchymal stem/stromal cell (BMSC) function and bone homeostasis. A critical problem is that aging triggers impaired localization, proliferation, survival, and differentiation of the osteogenic progenitor cell population in the bone marrow (BM), specifically BMSCs. A critical barrier to preventing these changes is identifying key regulatory pathways, and being able to alter or correct them. We have identified BMSC epigenetic changes in the microRNA miR-29b-1-5p, that appears to cross-talk with histone deacetylase 3 (Hdac3), a second epigenetic regulatory system. Further, we have identified that the oxidized tryptophan (TRP) metabolite kynurenine (KYN) alters these specific epigenetic regulatory molecules in BMSCs, which in turn directly, and via SDF-1 signaling pathways, affect cell survival, osteogenesis, osteoblastic lipid storage, and bone formation. Significantly, miR-29b-1-5p, which increases with aging in BMSCs, belongs to the miR29 family of miRNAs that have been shown to be critical in extracellular matrix homeostasis and osteogenesis. One novel aspect is that miR29b-1-5p is the “passenger strand”, which is normally thought to be degraded leaving the complementary miR-29b-1-3p “guide strand” as the functional miRNA; with aging, however, our data suggest that this passenger strand is an important effector of BMSC dysfunction. Importantly, miR-29b- 1-5p, which targets SDF-1, is upregulated by KYN while Hdac3 is down regulated leading to increased lipid storage and dysfunction in BM osteoprogenitor cells and OBs. Understanding the upstream mechanisms that drive these previously unknown age-associated changes in miR-29b-1-5p and Hdac3 is a critical goal because we have demonstrated that these two interacting systems regulate SDF-1 expression and suppress BMSC osteogenesis and survival pathways while increasing BM fat storage. We propose to test the hypothesis that the elevated, age-related levels of KYN drive the increased expression of miR-29b-1-5p and inhibition of Hdac3 expression, with downstream effects on bone homeostasis via SDF-1 and its receptor CXCR4, or directly by targeting additional osteogenic genes both in BMSCS and OBs. Our objectives are to test new hypotheses derived from our findings by manipulating the miRNAs and Hdacs we identified as changing with age in human/murine BMSCs to determine their effects on bone formation and turnover in vivo and at the molecular level on BMSC osteogenic function. We will test novel methods to reduce expression of these molecules, including inhibiting KYN generation, inhibiting KYN signaling pathways, or delivering synthetic anti-miRNAs to inhibit miR29b-1-5p. The impact of this project will be to clarify the roles of age-associated epigenetic changes in cross-talking BMSC miRNA and Hdac systems with the goal of identifying novel targets for reducing, or reversing, age-related bone loss and osteoporosis.

与衰老相关的骨质疏松症的机制仍不清楚，但是，我们最近的研究 小组和其他人认为这是一种干细胞疾病。我们一直在研究细胞因子SDF-1的作用 (CXCL12) 和 Hdac3 在骨髓间充质干细胞/基质细胞 (BMSC) 功能和骨稳态中的作用。 一个关键问题是衰老会导致细胞定位、增殖、存活和分化受损。 骨髓 (BM) 中的成骨祖细胞群，特别是 BMSC。一个关键障碍 防止这些变化的方法是确定关键的监管途径，并能够改变或纠正它们。我们 已鉴定出 BMSC 在 microRNA miR-29b-1-5p 中的表观遗传变化，该变化似乎与组蛋白相互作用 脱乙酰酶 3 (Hdac3)，第二个表观遗传调控系统。此外，我们还发现氧化 色氨酸 (TRP) 代谢物犬尿氨酸 (KYN) 改变 BMSC 中的这些特定表观遗传调节分子， 进而通过 SDF-1 信号通路直接影响细胞存活、成骨、成骨细胞脂质 储存和骨形成。值得注意的是，miR-29b-1-5p 在 BMSC 中随着衰老而增加，属于 miRNA 的 miR29 家族已被证明对细胞外基质稳态至关重要 成骨。一个新颖的方面是 miR29b-1-5p 是“过客链”，通常被认为是 降解，留下互补的 miR-29b-1-3p“引导链”作为功能性 miRNA；然而随着年龄的增长， 我们的数据表明该过客链是 BMSC 功能障碍的重要效应器。重要的是，miR-29b- 1-5p 靶向 SDF-1，KYN 上调，而 Hdac3 下调，导致脂质增加 BM 骨祖细胞和 OB 的储存和功能障碍。了解上游机制 驱动 miR-29b-1-5p 和 Hdac3 中这些以前未知的年龄相关变化是一个关键目标，因为 我们已经证明这两个相互作用的系统调节 SDF-1 表达并抑制 BMSC 成骨和生存途径，同时增加骨髓脂肪储存。我们建议检验以下假设： 与年龄相关的 KYN 水平升高导致 miR-29b-1-5p 表达增加并抑制 Hdac3 表达，通过 SDF-1 及其受体 CXCR4 对骨稳态产生下游影响，或直接通过 针对 BMSCS 和 OB 中的其他成骨基因。我们的目标是测试新假设 来自我们的发现，通过操纵 miRNA 和 Hdac，我们确定随着年龄的增长而变化 人/鼠 BMSC 以确定其对体内和分子水平骨形成和更新的影响 水平对 BMSC 成骨功能的影响。我们将测试减少这些分子表达的新方法， 包括抑制 KYN 生成、抑制 KYN 信号通路或将合成的抗 miRNA 传递至 抑制 miR29b-1-5p。该项目的影响将是阐明与年龄相关的表观遗传变化的作用 在 BMSC miRNA 和 Hdac 系统中进行串扰，目的是确定新的靶标以减少或 逆转与年龄相关的骨质流失和骨质疏松症。