Analysis of the roles of the Wnt-ligands Wnt9a and Wnt4 in adult bone and joint homeostasis

Wnt配体Wnt9a和Wnt4在成人骨和关节稳态中的作用分析

• 批准号: 375137860
• 负责人: Professorin Dr. Christine Hartmann
• 金额: --
• 依托单位: Institut für Muskuloskelettale Medizin
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/375137860?language=en
• 关键词: Analysis; roles; Wnt; ligands; Wnt9a

Osteoporosis (OP) and osteoarthritis (OA) are degenerative musculoskeletal diseases with a very high prevalence. They occur primarily in elderly people. The hallmarks of osteoporosis are: decreased bone mineral density, loss of bone and increased bone fragility. OA is also associated with bone alterations. Here, it is primarily the subchondral bone that changes during the course of the disease. In early OA, bone turnover is increased in the subchondral bone, while subchondral bone thickening is a characteristic feature of late OA. As such, drugs, such as the anti catalytically acting bisphosphonates and the anabolically active Teriparatide, which are normally used to treat OP, have been tested in OA animal models for potential beneficial effects. These studies showed that these drugs can alter disease progression. Wnt-ligands, amongst them Wnt9a and Wnt4, and members of Wnt signaling pathways have been implicated to play roles in OP and OA. In the project proposed here, we will examine the roles of Wnt9a and Wnt4 in adult bone and joint-homeostasis of the mouse using different conditional knockout approaches. The loss of Wnt9a in the limb mesenchyme results in the development of spontaneous OA-like changes in the joints of aged mice. The onset of these changes is accelerated upon additional loss of Wnt4 in the limb mesenchyme. In addition to the joint alterations, we observed alterations in the bone, which are not restricted to the subchondral region. In the proposed project we want to complete the phenotypic characterization of the musculoskeletal alterations upon loss of Wnt9a and the combined loss of Wnt9a and Wnt4 in the limb mesenchyme. Both Wnt-ligands are produced by cells in the joint as well as by osteoblasts. Hence, in order to phenotypically distinguish between the contribution of the different cells / tissues to the observed skeletal alterations we want to examine the phenotypic changes after postnatal deletion of Wnt9a or Wnt4 in superficial chondrocytes using the Prg4-Cre line and in osteoblast precursors using the Osx-Cre line. Using in vivo and in vitro approaches, we expect to answer the questions which signaling pathways are used by the two Wnt-ligands in osteoblasts, articular chondrocytes, and synoviocytes and whether these differ between the Wnt-ligands or the different cell types. In addition, we want to generate transgenic mice expressing increased levels in superficial articular chondrocytes to see whether this has a beneficial effect on OA-progression in a surgically induced model of OA.

骨质疏松症（OP）和骨关节炎（OA）是患病率非常高的退行性肌肉骨骼疾病。它们主要发生在老年人中。骨质疏松症的特点是：骨矿物质密度降低、骨丢失和骨脆性增加。 OA 还与骨骼改变有关。在这里，在疾病过程中主要是软骨下骨发生变化。在早期 OA 中，软骨下骨中的骨转换增加，而软骨下骨增厚是晚期 OA 的特征。因此，通常用于治疗 OP 的抗催化双膦酸盐和合成代谢活性特立帕肽等药物已在 OA 动物模型中进行了潜在有益作用的测试。这些研究表明这些药物可以改变疾病进展。 Wnt 配体（其中包括 Wnt9a 和 Wnt4）以及 Wnt 信号通路成员在 OP 和 OA 中发挥作用。在此提出的项目中，我们将使用不同的条件敲除方法检查 Wnt9a 和 Wnt4 在成年小鼠骨和关节稳态中的作用。肢体间充质中 Wnt9a 的缺失会导致老年小鼠关节中出现自发性 OA 样变化。当肢体间质中 Wnt4 额外丢失时，这些变化的发生会加速。除了关节改变之外，我们还观察到骨骼的改变，这些改变不仅限于软骨下区域。在拟议的项目中，我们希望完成肢体间质中 Wnt9a 丢失以及 Wnt9a 和 Wnt4 联合丢失时肌肉骨骼变化的表型表征。两种 Wnt 配体均由关节细胞和成骨细胞产生。因此，为了在表型上区分不同细胞/组织对观察到的骨骼改变的贡献，我们希望使用 Prg4-Cre 系检查表型软骨细胞中 Wnt9a 或 Wnt4 出生后删除后的表型变化，并使用 Osx-Cre 系检查成骨细胞前体细胞中 Wnt9a 或 Wnt4 的表型变化。使用体内和体外方法，我们期望回答成骨细胞、关节软骨细胞和滑膜细胞中两种Wnt配体使用哪些信号通路以及这些信号通路在Wnt配体或不同细胞类型之间是否不同的问题。此外，我们希望培育出浅表关节软骨细胞表达水平升高的转基因小鼠，以观察这是否对手术诱导的 OA 模型中的 OA 进展产生有益影响。