Study of osteoblast regulation in TNF-mediated bone loss

 描述(由申请人提供)：父母资助的目标是调查Notch信号在炎症性骨质疏松症中的作用。我们发现，间充质干/祖细胞中Notch的持续激活限制了其成骨细胞(OB)的分化潜能，并导致骨丢失，这可以被Notch抑制剂、DAPT和Thapsigarin[1]阻止。我们的研究结果表明，Notch抑制剂可以作为骨合成代谢药物。然而，由于全身分布，Notch抑制剂有严重的副作用[2]，限制了它们在骨质疏松症等常见疾病中的使用。因此，制造骨靶向Notch抑制剂以减少其全身副作用将是一个非常有吸引力的方法。在这次修订中，我们将组成一个跨学科的团队，成员包括骨生物学家(Xing博士，父母拨款的PI)和化学家(Boeckman博士，修订的共同PI；Ebetino博士，修订的顾问)，通过使用新型氨基甲酸酯连接物将Bortezomib与双膦酸偶联，从而设计和合成靶向Bortezomib的骨。提出了两个特殊的目标。在目标1中，我们将设计和合成骨靶向Bortezomib结合物，在目标2中，我们将在OB培养和小鼠骨折愈合中检测骨靶向Bortezomib结合物的生物活性。如果我们成功，我们将使用类似的方法合成骨靶向Notch抑制剂，以减少它们在治疗炎症性骨质疏松症方面的毒性作用，这是父母拨款的主要目标，可能还会减少其他与炎症相关的骨丢失。这项应用还将为Xing博士和Boeckman的实验室带来新的方向：了解泛素-蛋白酶体系统在老年人群骨折修复中的作用，重点是间充质干细胞/祖细胞(Xing的实验室)；以及在其他药物和化合物中使用新型化学连接物，这将开启骨靶向化学的新策略(Boeckman实验室)。

 DESCRIPTION (provided by applicant): The goal of the parent grant is to investigate the role of Notch signaling in inflammatory osteoporosis. We found that persistent activation of Notch in mesenchymal stem/progenitor cells limits their osteoblast (OB) differentiation potential and causes bone loss, which can be prevented by Notch inhibitors, DAPT and Thapsigarin [1]. Our findings suggest that Notch inhibitors could be used as bone anabolic agents. However, Notch inhibitors have severe adverse effects due to systemic distribution [2], limiting their use in common diseases such as osteoporosis. Thus, making bone targeted Notch inhibitors to reduce their systemic side effects will be a very attractive approach. In this revision, we will form a ne interdisciplinary team including a Bone Biologist (Dr. Xing, the PI of the parent grant) and Chemists (Dr. Boeckman, a co-PI of the revision; Dr. Ebetino, consultant of the revision) to design and synthesize bone targeted Bortezomib by conjugating it to a bisphosphonate using a novel carbamate linker that will release Bortezomib from the Bortezomib- bisphosphonate. Two special aims are proposed. In aim 1, we will design and synthesize bone-targeted Bortezomib conjugates and in aim 2, we will examine the bioactivity of bone-targeted Bortezomib conjugates in OB cultures and in mouse fracture healing. If we are successful, we will use a similar approach to synthesize bone targeted Notch inhibitors to reduce their toxic effects in the treatment of inflammatory osteoporosis, a main goal of the parent grant, and perhaps in other bone loss related to inflammation. The application will also lead to new directions for both Drs. Xing and Boeckman's lab: understanding the role of the ubiquitin- proteasome system in bone fracture repair in the aged population with a focus on mesenchymal stem/progenitor cells (Xing's lab); and using a novel chemical linker in other drugs and compounds, which will open a new strategy of bone targeting chemistry (Boeckman's lab).