PTH2R在骨重建中的作用研究

Parathyroid hormone（PTH）is an important regulator for bone remodeling. There are two types of PTH receptors in mammals, type 1 PTH receptor (PTH1R) and type 2 PTH receptor (PTH2R).Both PTH1R and PTH2R can be activated by PTH. Although the function of PTH1R in bone has been well established, the physiological role of PTH2R in bone remodeling is largely unknown. Our preliminary study identified that PTH2R gene was a potential and sex-specific risk gene of osteoporosis in a meta-analysis based on >9000 subjects. In addition, we detected that PTH2R was strongly expressed in osteoblasts and osteoclasts. All these results indicated that PTH2R may be a functional PTH receptor in bone. In this proposal, we will test this hypothesis by the following experiments. First, we will determine the role of PTH2R in osteoblastogenesis and osteoclastogenesis and the underlying mechanisms with comprehensive in vitro gain- and loss-of-function approaches. Second, we will determine the effects of PTH2R deficiency on bone remodeling by characterizing the skeletal phenotype of the osteoblast-specific PTH2R knockout mice. In addition, we will determine the role of 4 SNPs in the 3' downstreams of the PTH2R gene in regulation of PTH2R expression in osteoblasts. Therefore, the outcome of this proposed study will demonstrate a novel and fundamental mechanism by which PTH-PTH2R signaling pathway regulates bone remodeling, which should shed lights on development of novel anabolic interventions for osteoporosis and other skeletal diseases with bone loss.

甲状旁腺素（PTH）是调节骨代谢的重要激素之一。哺乳动物存在PTH1R和PTH2R两种PTH受体。PTH1R 和PTH2R均可被PTH 活化。PTH1R介导PTH信号参与骨代谢的机制已得到深入研究。然而PTH2R在骨代谢中的作用却基本未见报道。我们前期研究发现PTH2R基因是一个潜在的并具有性别特异性的骨质疏松风险基因，而且发现PTH2R在成骨细胞和破骨细胞均高表达，提示PTH2R可能是骨代谢中PTH信号的功能性受体。围绕这一假设，本项目将在体外细胞培养体系，通过PTH2R突变型及野生型基因的表达/过表达, 确定该基因在成骨和破骨发生中的作用；利用成骨细胞特异性PTH2R基因敲除小鼠模型， 确定PTH2R缺失对骨代谢的影响；此外，也将研究rs11696050 等4个单核苷酸多态性在PTH2R 基因表达中的调控作用。本项目有望揭示PTH信号调节骨代谢的一种新的基础性机制。

骨质疏松是一种严重威胁人类健康的多基因复杂疾病。加强骨质疏松分子遗传机理研究能够为该病的有效预防、诊断和治疗提供科学依据，具有重要意义。本项目开展了对GEFOS2等多个骨健康全基因组关联分析研究的meta分析，进一步确认了多个与人群骨密度关联的PTH2R基因区的单核苷酸多态性。也通过多重组学（基因组-转录组-蛋白质组）数据挖掘分析了PTH2R在骨代谢中的可能作用。通过免疫组织化学和细胞免疫荧光实验检测到PTH2R基因在成骨细胞高表达。利用体外培养的MC3T3-E1, C2C12细胞成骨诱导体系，揭示PTH2R基因过表达后成骨细胞特异性基因OCN，ALP等表达水平提升，并激活了细胞内的cAMP信号通路。本项目构建了PTH2R基因敲除小鼠模型。通过二代测序技术，鉴定了成骨细胞分化过程中一系列差异表达的长链非编码RNA及mRNA，其中包含一些从未被注释过的新长链非编码RNA，并对与PTH诱导的成骨及破骨分化密切相关的Ptger2基因与长链非编码RNA(ID 略)间的调控机制进行了研究。到目前为止，发表SCI论2篇，培养硕士生4人(已毕业2人)、博士研究生1人。