Effects of Osteocalcin and Osteopontin on Damage Morphology and Bone Fragility

描述(申请人提供)：在父母资助下进行的研究表明，包括骨钙素(OC)和骨桥蛋白(OPN)在内的非胶原基质(NCPs)蛋白在纳米级充当连接骨矿的蛋白质，并影响骨折的起始。这些新发现表明，OC和OPN与羟基磷灰石矿物(HA)以及彼此之间的相互作用可能会影响有机-矿物质的相互作用，并确定骨骼的抗骨折能力(韧性)。OC和OPN都调节着骨中的矿化，它们与HA相互作用的性质也可能决定骨中HA血小板的结构和水化作用。由于骨骼中的骨折受水化程度的影响，涉及有机-矿物质界面和蛋白质-蛋白质相互作用的变形和破坏，因此这些信息对于了解骨质量和骨脆性至关重要。因此，本项目的总体目标是确定OC和OPN与羟基磷灰石矿物(HA)的相互作用以及相互作用，并评估它们对HA血小板的结构和水化、有机-矿物质界面和骨骼韧性的影响。基因敲除小鼠(OC-/-，OPN-/-，OC-OPN-/-)及其WT仔鼠的骨骼，以及蛋白质(OC，OPN)将接受固体核磁共振(SS NMR)和原子力光谱、吸附层析或断裂力学测试，以确定：(H1)OC和OPN与HA的相互作用决定了HA血小板的结构和水化，并改变了骨中有机-矿物质界面；和(H2)OC和OPN与HA和OPN相互作用，形成骨中的有机-矿物质界面，这些结合的强度决定了骨的抗折性(韧性)。与NIAMS和本RFA-AR-13-003的使命一致，该项目将原子水平的相互作用与骨骼质量和骨折联系起来的成功结果将导致预防和修复骨骼骨折的新方法。新的跨学科团队包括一名骨骼力学专家(Deepak Vashishth博士，Pi on Parent Grant)，一名结构生物学家和固体核磁共振专家(Scott McCallum博士)，以及一名化学工程师和基于羟基磷灰石的柱层析专家(Steven Cramer博士)，这也将帮助NIAMS应对骨骼研究的新挑战。

DESCRIPTION (provided by applicant): Studies conducted under the parent grant suggest that non-collagenous matrix (NCPs) proteins including osteocalcin (OC) and osteopontin (OPN) act as link proteins to bone mineral and influence the initiation of bone fracture at the nanoscale These new findings suggest that the interaction of OC and OPN with hydroxyapatite mineral (HA) and with each other may influence organic-mineral interactions and determine bone's resistance against fracture (toughness). Both OC and OPN regulate mineralization in bone and the nature of their interactions with HA may also determine the structure and hydration of HA platelets in bone. Because fractures in bone are affected by the level of hydration and involve the deformation and disruption of the organic-mineral interface and protein-protein interactions, this information is critical to the understanding of bone quality and bone fragility. Thus the overall goal of this project is to determine the interaction of OC and OPN with hydroxyapatite mineral (HA) and with each other and evaluate their effects on the structure and hydration of HA platelets, organic-mineral interface and bone toughness. Bones of knockout mice (OC-/-, OPN-/-, OC-OPN-/-) and their WT littermates, available through the parent grant, as well as proteins (OC, OPN) will be subjected to Solid State Nuclear Magnetic Resonance (SS NMR) and Atomic Force Spectroscopy, Adsorption Chromatography or Fracture Mechanics Testing to determine whether: (H1) The interaction of OC and OPN with HA determines the structure and hydration of HA platelets and alters the organic-mineral interface in bone; and (H2) OC and OPN interact with HA and with each other to form the organic-mineral interface in bone and the strength of these bindings determines bone resistance against fracture (toughness). Consistent with the missions of NIAMS and this RFA-AR-13-003, a successful outcome of this project linking atomic level interactions to bone quality and fracture will lead to new approaches for preventing and repairing bone fractures. The new interdisciplinary team of a bone mechanics expert (Dr. Deepak Vashishth, PI on parent grant), a structural biologist and a solid state NMR expert (Dr. Scott McCallum) and a chemical engineer and an expert on hydroxyapatite-based column chromatography (Dr. Steven Cramer) will also help NIAMS to address new challenges in bone research.