ROLE OF CASPASE-2 IN OSTEOCOLAST APOPTOSIS AGE-EePENDENT OSTEOPOROSIS

CASPASE-2 在破骨细胞凋亡中的作用年龄相关性骨质疏松症

• 批准号: 7233105
• 负责人: BRIAN A. HERMAN
• 金额: $ 26.94万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-01 至 2011-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7233105
• 关键词: Affect; Age; Aging; Animals; Antioxidants; Apoptosis; Biochemical Reaction; Bone Resorption; Calcium/calmodulin-dependent protein kinase; Calmodulin; Caspase; Cessation of life; Data; Disease; Down-Regulation; Elderly; Endopeptidases; Funding; Knockout Mice; Life; Light; Mediating; Mediator of activation protein; Mitochondria; Mus; NADP; Numbers; Organ; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis; Oxidants; Oxidative Stress; Peptide Hydrolases; Phosphotransferases; Play; Rate; Regulation; Role; Skeleton; Testing; Urine; Wild Type Mouse; base; bone; bone loss; caspase-2; in vivo; oxidation; prevent; pro-caspase-2

Bone is a living organ that is maintained through continuous formation of new bone by osteoblasts and resorption of exiting bone by osteoclasts. Loss of bone mass at advanced ages causes osteoporosis. Caspase-2 is a protease that is involved in programmed cell death (apoptosis). During the last funding period, we found that caspase-2 is an important regulator of bone mass in aging animals. Our critical observation was that aging-associated bone loss in old (24-26 month) caspase-2 null mice was more severe than that in the same age wild type mice. The objective of this proposal is to further study the role of caspase-2 in aging skeleton. Our hypothesis is that caspase-2 mediates mitochondrial-dependent apoptosis of aging osteoclasts, which is induced by oxidative stress in vivo. Lack of caspase-2 activity results in reduced apoptosis of aging osteoclasts, leading to increased bone resorption. To test this hypothesis, first, we will compare the rate of bone formation and bone resorption in old caspase-2 null and wild type mice to show that caspase-2 affects bone resorption. Next, we will compare the apoptosis rate in aging osteoclasts that have increased/decreased antioxidant capacity to show that oxidative stress is a cause of spontaneous apoptosis of aging osteoclasts. Then, we will compare the apoptosis rate of caspase-2 (-/-)and (+/+) aging osteoclasts to show that caspase-2 plays an important role in the spontaneous apoptosis of aging osteoclasts. Finally, we will compare the apoptosis rate in aging osteoclasts that have both altered antioxidant activity and caspase-2 activity to show that caspase-2 is a mediator of oxidative stress-induced apoptosis. Calmodulin (CaM) dependent kinase II (CaMK II) can phosphorylate procaspase-2 and prevent its activation. NADPH, which provides reducing equivalent for various biochemical reactions to scavenge oxidants, also inhibits the activation of procaspase-2 by enhancing CaMK II function. Based on these findings, we will test the hypothesis that oxidative stress activates caspase-2 in aging osteoclasts through down-regulation of NADPH/CaMK II activity by examining the level of NAPDH and oxidation of CaM and CaMK II. Osteoporosis is a serious disease that affects the elderly. The main strategy and mechanism of action of current anti-osteoporosis therapy is to induce osteoclast apoptosis. Therefore, this study will shed the light on the mechanism of apoptosis in osteoclasts and open new avenues for new anti-osteoporosis therapies.

骨是通过成骨细胞持续形成新骨来维持的活器官， 通过破骨细胞吸收排出的骨。老年骨质流失会导致骨质疏松症。 胱天蛋白酶-2是参与程序性细胞死亡（凋亡）的蛋白酶。在最后一次融资中 期间，我们发现caspase-2是衰老动物骨量的重要调节因子。我们的关键 观察到老年（24-26个月）胱天蛋白酶-2缺失小鼠中与衰老相关的骨丢失更严重 与同龄野生型小鼠相比。这项建议的目的是进一步研究 caspase-2在衰老骨骼中的作用。我们的假设是caspase-2介导了细胞凋亡 老化破骨细胞，这是由体内氧化应激诱导的。缺乏半胱天冬酶-2活性导致 减少老化破骨细胞的凋亡，导致骨吸收增加。为了验证这个假设，首先， 我们将比较老年胱天蛋白酶-2缺失小鼠和野生型小鼠的骨形成和骨吸收速率， 显示胱天蛋白酶-2影响骨吸收。接下来，我们将比较老化破骨细胞的凋亡率 具有增加/降低的抗氧化能力，以表明氧化应激是自发性的 衰老破骨细胞的凋亡。然后，我们将比较caspase-2（-/-）和（+/+）衰老的凋亡率 破骨细胞，以显示caspase-2在衰老的自发性细胞凋亡中起重要作用 破骨细胞最后，我们将比较老化破骨细胞的凋亡率， 抗氧化活性和半胱天冬酶-2活性，以表明半胱天冬酶-2是氧化应激诱导的 凋亡钙调素依赖性激酶II（CaMK II）可磷酸化半胱氨酸天冬氨酸蛋白酶原-2， 其激活。NADPH，它为各种生化反应提供还原当量， 氧化剂，也通过增强CaMK II功能抑制半胱天冬酶原-2的活化。基于这些 研究结果，我们将测试假设，氧化应激激活caspase-2在老化破骨细胞，通过 通过检测NAPDH水平和CaM氧化下调NADPH/CaMK II活性， CaMK II.骨质疏松症是影响老年人的一种严重疾病。的主要策略和机制 目前抗骨质疏松治疗的作用是诱导破骨细胞凋亡。因此，本研究将 阐明破骨细胞凋亡的机制，为新的抗骨质疏松药物开辟新的途径 治疗