Skeletal Functions of Polycystins and TAZ

多囊蛋白和 TAZ 的骨骼功能

基本信息

批准号：
10188427
负责人：
L DARRYL QUARLES
金额：
$ 32.44万
依托单位：
UNIVERSITY OF TENNESSEE HEALTH SCI CTR
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-24 至 2023-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10188427
关键词：
Adipocytes Adipose tissue Age-Related Osteoporosis Aging Agonist Agreement Binding Bone Formation Inhibition Bone Marrow C-terminal Calcium Cell Communication Cells Chemicals Cilia Complex Critical Pathways Cues Development Exhibits Extracellular Matrix Fatty acid glycerol esters Future GTP-Binding Protein alpha Subunits, Gs Genetic Goals Homeostasis Impairment In Vitro Link Marrow Mechanical Stimulation Mechanics Mediating Microgravity Modeling Molecular Mus Mutant Strains Mice Nature Nuclear Translocation Osteoblasts Osteocalcin Osteogenesis Osteopenia Osteoporosis Osteoporosis prevention Outcome PKD2 protein PPAR gamma Pathogenesis Peroxisome Proliferator-Activated Receptors Pharmaceutical Preparations Pharmacology Phenotype Prevention Process Proprotein Convertase 1 Proprotein Convertase 2 Role Signal Pathway Signal Transduction Stretching Stromal Cells Structure Tail Testing Transcription Coactivator Transcriptional Coactivator with PDZ-Binding Motif base bone bone disuse atrophy bone loss bone mass clinically relevant conditional knockout experimental study fluid flow gamma secretase genetic corepressor improved in vivo lipid biosynthesis loss of function mechanical force mechanical load mechanotransduction mouse model new therapeutic target novel physical inactivity polycystic kidney disease 1 protein pre-clinical prevent response sarcopenia shear stress skeletal skeletal unloading small molecule therapeutic target validation studies virtual screening

项目摘要

Defective bone mechanosensing and skeletal unloading contribute to age-related and disuse osteoporosis. The molecular mechanisms that transduce the osteoblast response to physical forces in the bone microenvironment to maintain skeletal homeostasis are poorly understood. We discovered a novel mechanosensing complex in osteoblasts created by an interaction between polycystins (PC1, Pkd1 and PC2, Pkd2) and TAZ (transcriptional coactivator with PDZ-binding motif). The PC1/PC2/TAZ complex functions to sense and transduce mechanical loading into anabolic bone responses. Loss of either Pkd1 or Taz in mice results in osteopenia characterized by a reciprocal decrease in osteoblast-mediated bone formation and an increase in adipocytes in bone marrow. Compound heterozygous mice lacking one copy of Pkd1 and TAZ exhibit additive decrements in bone mass, impaired osteoblast-mediated bone formation and enhanced accumulation of bone marrow fat. The PC1 C-ter- minal tail (PC1-CTT) binds to and facilitates TAZ nuclear translocation to co-activate Runx2-mediated osteoblas- togenesis and co-repress PPAR-mediated adipogenesis in vitro. Computational approaches using structure- based virtual screening discovered a novel agonist (mechanomimetic) that binds to the PC1:PC2 C-terminal tail helix: helix interaction region and activates polycystins/TAZ signaling. These observations provide the scientific premise for the hypothesis that skeletal responses to loading are transduced by a mechanosensing complex in osteoblasts formed by interactions between PC1, PC2 and TAZ. Aim 1 tests the hypothesis that Pkd1/TAZ have interdependent functions in mature osteoblasts to regulate bone mass through the reciprocal stimulation of os- teoblastogenesis and inhibition of adipogenesis. In this aim, we will examine the effects of TAZ to differentially regulate osteoblastogenesis and adipogenesis in vitro and in vivo by creating mice with conditional knockout of Taz in mature osteoblasts (TazOc-cko). We will further test for genetic interactions between Taz and Pkd1 by creating compound Pkd1Oc-cko/Taz Oc-cko mice. Aim 2 tests the hypothesis that the Pkd1/TAZ complex mediates the response of osteoblasts to mechanical loading in vivo and in vitro using single and compound Pkd1 and Taz loss-of-function mouse models and osteoblast cultures. Aim 3 tests the hypothesis that activation of the PC1/PC2/TAZ with a novel “mechanomimetic” will increase bone mass by stimulating osteoblastogenesis and inhibiting adipogenesis. Our impact will be to provide a new understanding of the molecular mechanisms medi- ating the skeletal response to loading by validating the PC1/PC2/TAZ mechanosensing complex in osteoblasts. In this new schema, PC1-CTT and TAZ form an integrative mechanosensing complex in cells within the osteo- blast lineage to differentially regulate Runx2-dependent osteoblastogenesis and PPARγ-mediated adipogenesis in response to physical cues in the bone microenvironment. The polycystins/TAZ complex is also a potential therapeutic target for treating osteoporosis caused by skeletal unloading; and the newly discovered first-in-class mechanomimetic provides a chemical probe to test if targeting polycystins/TAZ results in increased bone mass.

有缺陷的骨机械传感和骨骼卸载会导致与年龄相关的骨质疏松症和废用性骨质疏松症。转导成骨细胞对骨微环境中物理力反应的分子机制我们对维持骨骼稳态的机制知之甚少。多囊蛋白（PC1、Pkd1 和 PC2、Pkd2）与 TAZ（转录因子）之间相互作用产生的成骨细胞 PC1/PC2/TAZ 复合体具有感知和转导机械力的功能。小鼠中 Pkd1 或 Taz 的缺失会导致骨质减少，其特征是成骨细胞介导的骨形成的相互减少和骨髓中脂肪细胞的增加。缺乏一份 Pkd1 和 TAZ 的复合杂合小鼠表现出骨量的累加性减少，成骨细胞介导的骨形成受损并增加骨髓脂肪的积累。 minal tail (PC1-CTT) 结合并促进 TAZ 核转位，共同激活 Runx2 介导的成骨细胞使用结构计算方法在体外共同抑制 PPAR 介导的脂肪生成。基于虚拟筛选发现了一种新型激动剂（拟力学），可与 PC1:PC2 C 末端尾部结合螺旋：螺旋相互作用区域并激活多囊蛋白/TAZ 信号传导。这些观察结果提供了科学依据。骨骼对负载的反应是由机械传感复合体转导这一假设的前提 PC1、PC2 和 TAZ 之间相互作用形成的成骨细胞测试了 Pkd1/TAZ 的假设。成熟成骨细胞中相互依赖的功能，通过os-的相互刺激来调节骨量为此，我们将研究 TAZ 对脂肪生成的不同影响。通过条件性敲除小鼠，在体外和体内调节成骨细胞生成和脂肪生成成熟成骨细胞 (TazOc-cko) 中的 Taz 我们将通过进一步测试 Taz 和 Pkd1 之间的遗传相互作用。创建复合 Pkd1Oc-cko/Taz Oc-cko Aim 2 小鼠测试 Pkd1/TAZ 复合物介导的假设。使用单一和复合 Pkd1 和 Taz 观察成骨细胞对体内和体外机械负荷的反应目标 3 测试功能丧失小鼠模型和成骨细胞培养物的激活的假设。 PC1/PC2/TAZ 具有新颖的“拟力学”功能，可通过刺激成骨细胞生成来增加骨量我们的影响将是提供对分子机制的新认识。通过验证成骨细胞中的 PC1/PC2/TAZ 机械传感复合物来评估骨骼对负载的反应。在这个新模式中，PC1-CTT 和 TAZ 在骨细胞内形成了一个整合的机械传感复合体。母细胞谱系差异调节 Runx2 依赖性成骨细胞生成和 PPARγ 介导的脂肪生成响应骨微环境中的物理信号，多囊蛋白/TAZ复合物也是一种潜在的。治疗骨骼卸载引起的骨质疏松症的治疗靶点，是新发现的首创；拟力学提供了一种化学探针来测试靶向多囊蛋白/TAZ 是否会导致骨量增加。