Genetic and Chemical Biological Studies of a Novel Wnt Inhibitor Tiki2

新型 Wnt 抑制剂 Tiki2 的遗传和化学生物学研究

基本信息

批准号：
8334028
负责人：
Xi He
金额：
$ 57.38万
依托单位：
BOSTON CHILDREN'S HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-09-16 至 2016-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8334028
关键词：
Adult Age Aging-Related Process Alleles Binding Biochemical Biological Biology Biomechanics Bone Development Bone Diseases Bone Growth Bone Regeneration Bone Resorption Bone Tissue Cell Communication Cell Line Cells Chemicals Communication Complex Data Defect Disease Drug Delivery Systems Embryonic Development Enzymes Exhibits Family Financial compensation Fracture Gene Expression Generations Genes Genetic Genetic Transcription Homeostasis Human Human Activities Human Genetics In Vitro Integral Membrane Protein LDL-Receptor Related Proteins Ligands Link Lipids Lipoproteins Mechanics Mediating Methods Modification Mus Mutant Strains Mice Mutation Organ Osteoblasts Osteocytes Osteogenesis Osteoporosis Palmitates Pathway interactions Phenotype Physiological Prevention Property Proteins Regulation Regulatory Pathway Risk Role Screening procedure Signal Transduction Site Staging Stimulus Tamoxifen Therapeutic Therapeutic Intervention Time Tissues Wnt proteins Woman adduct aging population bone bone cell bone mass cell type chemical genetics gain of function mutation genetic manipulation global health in vivo inhibitor/antagonist interest loss of function men mouse model new therapeutic target novel novel therapeutics programs receptor response small molecule therapeutic target

项目摘要

DESCRIPTION (provided by applicant): Osteoporosis and bone fractures are global health problems. Identification of new therapeutic targets and strategies are of paramount importance. Signaling by the Wnt family of secreted proteins has emerged as a key pathway for human bone mass regulation, as loss-of-function and 'gain-of-function' mutations in Wnt coreceptor LRP5 are associated with familial osteoporosis and high bone mass diseases, respectively. Wnt/LRP5 signaling primarily regulates the osteoblast lineage and bone generation, providing a potential avenue for therapeutics that stimulates bone growth. Remarkably secreted Wnt antagonists are expressed in bone and modulate Wnt/LRP5 signaling locally, and thus offer treatment opportunities targeting bone specifically. Indeed Sclerostin, an osteocyte-specific secreted factor that binds to and inhibits LRP5, has become a key drug target for osteoporosis. We have identified a new family of Wnt antagonists, referred to as Tiki proteins, which likely are novel enzymes that post-translationally modify and inactivate Wnt ligands. We have generated Tiki2-/- mutant mice, which surprisingly are viable but exhibit high bone mass, suggesting that Tiki2, like Sclerostin, is an important negative regulator of bone homeostasis. Because of its enzymatic activity human TIKI2 may be an ideal target for small molecule inhibitors for potential therapeutic intervention for osteoporosis. We propose four aims to investigate the role of Tiki2 in bone biology and potential therapeutic implications. In Aim 1, we will characterize the high bone mass phenotype of Tiki2-/- mutant mice, employing histological, biochemical and biomechanical methods. We will also examine in details the expression of Tiki2 in bone cell types, its regulation in bone by anabolic and mechanical stimuli. In Aim 2, we will generate mutant mice with conditional Tiki2 deletion in the bone and in the adulthood via cell type- specific and a tamoxifen-inducible Cre lines. These studies will define the site and stage of Tiki2 action in bone and in the aging process. In Aim 3, we will investigate human TIKI2 (and TIKI1) bone-related functions and biochemical properties in vitro. We will investigate TIKI2 and TIKI1 expression in bone, and study whether TIKI2 and TIKI1 regulates bone formation in human osteoblast-like cell lines, and characterize the specific Wnt proteins that are modified/inactivated by TIKI proteins in bone mass regulation. In Aim 4, we will identify small molecule inhibitors of TIKI2 via chemical compound screening and to evaluate their potential in bone growth stimulation in vitro and in vivo. As a new class of Wnt antagonists with an enzymatic activity, TIKI proteins are ideal targets for small molecule inhibitors for use in experimental manipulation and therapeutic intervention. We will perform a high throughput chemical compound screen to identify Tiki2 inhibitors for their potential applications in stimulating bone growth. These studies together represent a comprehensive analysis of TIKI function in bone biology via genetic, biochemical and chemical biological methods, and may discover potential novel therapeutics for osteoporosis and bone regeneration.

描述（由申请人提供）：骨质疏松症和骨折是全球健康问题。识别新的治疗靶标和策略至关重要。 Wnt家族的信号已成为人类骨骼调节的关键途径，因为Wnt Corecector LRP5的功能丧失和“功能障碍”突变与家族性骨质疏松症和高骨质量疾病有关。 WNT/LRP5信号主要调节成骨细胞谱系和骨产生，为刺激骨骼生长的疗法提供了潜在的途径。明显分泌的Wnt拮抗剂在骨骼中表达，并在本地调节Wnt/LRP5信号，因此提供针对骨骼的治疗机会。确实，硬化蛋白是结合并抑制LRP5的骨细胞特异性分泌因子，已成为骨质疏松症的关键药物靶标。我们已经确定了一个新的Wnt拮抗剂家族，称为Tiki蛋白，可能是新型酶，后翻译后修饰和失活的Wnt配体。我们已经产生了Tiki2 - / - 突变小鼠，令人惊讶的是可行，但表现出很高的骨骼质量，这表明Tiki2像Sclerostin一样是骨稳态的重要负调节剂。由于其酶促活性，人类Tiki2可能是小分子抑制剂的理想靶标，用于潜在的骨质疏松症治疗干预。我们提出了四个旨在研究tiki2在骨骼生物学和潜在治疗意义中的作用的目的。在AIM 1中，我们将采用组织学，生化和生物力学方法的Tiki2 - / - 突变小鼠的高骨质量表型。我们还将详细检查骨细胞类型中Tiki2的表达，这是通过合成代谢和机械刺激在骨骼中调节的。在AIM 2中，我们将通过细胞类型（特异性和他莫昔芬诱导的CRE系）生成具有条件tiki2缺失的突变小鼠。这些研究将定义骨骼和衰老过程中TIKI2作用的位点和阶段。在AIM 3中，我们将在体外研究人类Tiki2（和Tiki1）骨相关功能和生化特性。我们将研究骨骼中的Tiki2和Tiki1表达，并研究Tiki2和Tiki1是否调节人成骨细胞样细胞系中的骨形成，并表征特异性的Wnt蛋白在骨量调节中被Tiki蛋白改性/失活的特定Wnt蛋白。在AIM 4中，我们将通过化学化合物筛选鉴定Tiki2的小分子抑制剂，并评估其体外和体内骨骼生长刺激的潜力。作为具有酶活性的新的WNT拮抗剂，Tiki蛋白是用于实验操作和治疗干预措施的小分子抑制剂的理想靶标。我们将执行高通量化合物化合物筛选，以鉴定其在刺激骨骼生长中的潜在应用的Tiki2抑制剂。这些研究一起通过遗传，生化和化学生物学方法对骨骼生物学的Tiki功能进行了全面分析，并可能发现潜在的骨质疏松和骨再生的新型治疗方法。