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：
8732464
负责人：
Xi He
金额：
$ 55.51万
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/8732464
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 Targeting 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 Signal Transduction Site Staging Stimulus Tamoxifen Therapeutic Therapeutic Intervention Time Tissues Wnt proteins Woman adduct aging population biophysical techniques 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 screening 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性的健康问题。确定新的治疗靶点和策略至关重要。 Wnt 分泌蛋白家族的信号传导已成为人类骨量调节的关键途径，因为 Wnt 辅助受体 LRP5 的功能丧失和“功能获得”突变与家族性骨质疏松症和高骨量疾病相关。分别。 Wnt/LRP5 信号传导主要调节成骨细胞谱系和骨生成，为刺激骨生长的治疗提供了潜在途径。显着分泌的 Wnt 拮抗剂在骨中表达并局部调节 Wnt/LRP5 信号传导，从而提供特异性针对骨的治疗机会。事实上，硬化素（Sclerostin）是一种结合并抑制 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点。我们已经鉴定出一个新的 Wnt 拮抗剂家族，称为 Tiki 蛋白，它们可能是翻译后修饰和灭活 Wnt 配体的新型酶。我们已经培育出 Tiki2-/- 突变小鼠，令人惊讶的是，它们能够存活，但表现出高骨量，这表明 Tiki2 与 Sclerostin 一样，是骨稳态的重要负调节因子。由于其酶活性，人 TIKI2 可能成为小分子抑制剂的理想靶标，用于骨质疏松症的潜在治疗干预。我们提出了四个目标来研究 Tiki2 在骨生物学中的作用和潜在的治疗意义。在目标 1 中，我们将采用组织学、生物化学和生物力学方法来表征 Tiki2-/- 突变小鼠的高骨量表型。我们还将详细检查 Tiki2 在骨细胞类型中的表达及其通过合成代谢和机械刺激对骨的调节。在目标 2 中，我们将通过细胞类型特异性和他莫昔芬诱导的 Cre 系产生在骨骼和成年期有条件 Tiki2 缺失的突变小鼠。这些研究将确定 Tiki2 在骨骼和衰老过程中作用的部位和阶段。在目标 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TIKI2和TIKI1在骨中的表达，研究TIKI2和TIKI1是否调节人成骨细胞样细胞系中的骨形成，并表征在骨量调节中被TIKI蛋白修饰/失活的特定Wnt蛋白。在目标 4 中，我们将通过化合物筛选来鉴定 TIKI2 的小分子抑制剂，并评估它们在体外和体内刺激骨生长的潜力。作为一类具有酶活性的新型 Wnt 拮抗剂，TIKI 蛋白是用于实验操作和治疗干预的小分子抑制剂的理想靶标。我们将进行高通量化合物筛选，以确定 Tiki2 抑制剂在刺激骨骼生长方面的潜在应用。这些研究共同代表了通过遗传、生化和化学生物学方法对 TIKI 在骨生物学中的功能进行的全面分析，并可能发现骨质疏松症和骨再生的潜在新疗法。