人源甲状旁腺激素受体1的小分子配体发现和构效关系研究

甲状旁腺激素受体1（PTH1R）属于B类GPCR，其天然配体为甲状旁腺激素，前期研究表明二者与血钙水平、骨生成和转换等密切相关，是公认的骨质疏松症治疗靶点。目前其肽类配体药物已在临床应用，但只能注射不能口服，治疗过程不便且价格昂贵。申请人课题组在2019年4月通过合作首次解析了全长人源PTH1R复合物激活态的三维分子结构，为小分子药物的研发奠定了基础。我们利用受体结构信息建立了虚拟筛选技术平台和基于下游cAMP信号检测的高通量实验筛选方法，通过对220余万个小分子的虚拟筛选和32000个化合物的实验筛选，发现了261个活性样品。本项目拟对这些样品进行复筛验证和结构优化改造，研究其构效关系及作用机制，并选取活性最优的活性配体开展系统的体内外抗骨质疏松症药效评价。项目的成功实施可望深入认识PTH1R受体配体的相互关系和下游信号转导机制，发现1-2个先导化合物用于后继药用开发。

The human parathyroid hormone receptor-1 (PTH1R) belongs to class B G protein-coupled receptor (GPCR) family and its cognate ligand is parathyroid hormone (PTH). Various studies indicate that PTH/PTH1R plays critical roles in skeletal development, calcium homeostasis and bone turnover. As a well-recognized drug target for osteoporosis, peptidic analogs of PTH targeting PTH1R are presently used in the clinic to treat osteoporosis. However, the need for injection and high price limit their use. We have recently revealed the cryo-electron microscopy structure of PTH1R bound to a long-acting PTH analog and the stimulatory G protein. It provides valuable insights and a solid foundation for discovering novel therapeutics against osteoporosis. Based on the structure information, we established both virtual and experimental high-throughput screening (HTS) platforms. The virtual screening technology was used to screen more than 2.2 million compounds. Of which, 32,000 were evaluated with the laboratory HTS method (based on cAMP measurement) resulting 261 active hits. In this project, we plan to validate these hits and conduct structural modification and optimization studies. The structure-activity relationship information gained will deepen our knowledge of the underlying mechanism of action that is crucial to evaluate their pharmacological property in vitro and in vivo. The outcome of this project will help us better understand the receptor activation and signal transduction pathways of PTH1R and discover one to two lead compounds for drug development to treat osteoporosis.