Differential Impact of Resveratrol and Resveratrol Mimetics Upon Aging Bone

描述（由申请人提供）： 骨质疏松症是老年人身体虚弱、发病率和死亡率增加的普遍原因，是骨吸收和骨形成之间不平衡的结果。Sirtuins与新陈代谢、长寿和健康有关。白藜芦醇（RSV）是一种去乙酰化酶激活化合物，可增强小鼠的骨矿物质密度（BMD），去乙酰化酶基因敲除小鼠表现出破骨细胞生成增加。SRT 2183和SRT 1720是合成的白藜芦醇模拟物（SyRM），旨在特异性激活sirtuin 1（Sirt 1），但越来越多的报告表明RSV和SyRM作用于Sirt 1以外的靶点。我们的初步数据表明：1）SyRM抑制c-Src磷酸化，肌动蛋白环的形成，破骨细胞的形成，和骨吸收，但RSV不; 2）SyRM也破坏肌动蛋白环，并抑制骨吸收在成熟的破骨细胞，但RSV不; 3）Sirt 1表达的敲除损害体内骨质量并增强离体破骨细胞生成，但是SyRM仍然抑制Sirt 1敲除细胞中肌动蛋白环和破骨细胞的形成; 4）RSV治疗年轻小鼠增加成骨细胞生成并减少破骨细胞生成;和5）RSV治疗非常年老的小鼠显著改善骨量和骨质量。假设和具体目标：我们假设SyRM抑制破骨细胞形成和功能的关键途径，包括c-Src磷酸化、Rho GT3激活和NFATc 1表达。有趣的是，尽管在体外缺乏效果，RSV在体内发挥了明显的益处，表明主要作用是对成骨细胞。我们认为，在体内治疗RSV和SyRM将恢复骨细胞骨吸收和成骨细胞骨形成之间的年轻平衡，提高骨密度和骨质量，但可能通过不同的机制。我们还假设SyRM可以独立于Sirt 1对骨产生有益作用。1.确定RSV、RSV模拟物和Sirt 1调节破骨细胞和成骨细胞形成的机制。这一目标的结果将回答的关键问题，是否SyRM抑制破骨细胞通过抑制c-Src磷酸化，Rho GT3激活，NFATc 1的表达和SyRM的影响是否依赖于Sirt 1。2.确定RSV、RSV模拟物和Sirt 1在体内对骨骼的影响。 这一目标的结果将回答以下关键问题：体内RSV和SyRM是否预防年龄相关和/或卵巢切除术诱导的骨质流失，RSV和SyRM是否对骨产生合成代谢和抗再吸收作用或两者兼而有之，以及RSV和SyRM的影响是否取决于Sirt 1基因表达。 迫切需要靶向药物来改善骨质量并减少骨质疏松症的不良后果。我们提出的研究将使我们能够更好地了解RSV和SyRM影响的潜在机制及其与Sirt 1表达的关系。鉴于老年人骨质疏松症的广泛和有害负担，我们的工作也将具有显著的临床影响，并可应用于临床中RSV和RSV模拟物的利用。

DESCRIPTION (provided by applicant): Osteoporosis is a widely prevalent contributor to frailty, increased morbidity, and mortality in the elderly and results from an imbalance between bone resorption and bone formation. Sirtuins have been implicated in metabolism, longevity, and healthspan. Resveratrol (RSV) is a sirtuin activating compound that enhances bone mineral density (BMD) in mice, and sirtuin knockout mice exhibit increased osteoclastogenesis. SRT2183 and SRT1720 are synthetic resveratrol mimetics (SyRMs) that were designed to specifically activate sirtuin1 (Sirt1), but an increasing number of reports suggest that RSV and SyRMs act on targets other than Sirt1. Our preliminary data demonstrate that: 1) SyRMs inhibit c-Src phosphorylation, actin ring formation, osteoclast formation, and bone resorption, but RSV does not; 2) SyRMs also disrupt actin rings and inhibit bone resorption in mature osteoclasts, but RSV does not; 3) knockout of Sirt1 expression impairs bone quality in vivo and enhances osteoclastogenesis ex vivo, but SyRMs still inhibit actin ring and osteoclast formation in Sirt1 knockout cells; 4) RSV treatment of young mice increases osteoblastogenesis and decreases osteoclastogenesis; and 5) RSV treatment of very old mice markedly improves bone mass and bone quality. Hypothesis and Specific Aims: We hypothesize that SyRMs inhibit critical pathways of osteoclast formation and function involving c-Src phosphorylation, Rho GTPase activation, and NFATc1 expression. Intriguingly, despite lack of effect in vitro, RSV exerts pronounced benefit in vivo, suggesting that the predominant effects are on osteoblasts. We propose that in vivo treatment with RSV and SyRMs will both restore the youthful balance between osteoclastic bone resorption and osteoblastic bone formation and enhancing bone mineral density and bone quality, but possibly via different mechanisms. We also hypothesize that the SyRMs can exert beneficial effects upon bone independent of Sirt1. 1. Determine the mechanisms whereby RSV, RSV mimetics, and Sirt1 regulate osteoclast and osteoblast formation. The results of this aim will answer the critical questions of whether or not SyRMs inhibit osteoclastogenesis by inhibiting c-Src phosphorylation, Rho GTPase activation, and NFATc1 expression and whether the effects of SyRMs depend upon Sirt1. 2. Determine the skeletal impacts of RSV, RSV mimetics, and Sirt1 in vivo. The results of this aim will answer the critical questions of whether or not in vivo RSV and SyRMs prevent age-related and/or ovariectomy-induced bone loss, whether RSV and SyRMs exert either anabolic and anti-resorptive effects on bone or both, and whether the impacts of RSV and SyRMs depend upon Sirt1 gene expression. There is a pressing need for targeted agents to improve the quality of bone and to reduce the adverse consequences of osteoporosis. Our proposed studies will permit us to understand better the mechanism(s) underlying the impacts of RSV and SyRMs and their relationship to Sirt1 expression. Our work will also have significant clinical impact given the widespread and deleterious burden of osteoporosis in the elderly and can be applied to the utilization of RSV and RSV mimetics in the clinic.