Analysis of transcription enhancing factor for PTH receptor that controls bone metabolism

甲状旁腺激素（PTH）和甲状旁腺激素相关蛋白（PTHrP）通过与成骨细胞上表达的G蛋白偶联的PTH/PTHrP受体（PTH 1 R）结合而发挥其对骨代谢的影响。大鼠、小鼠和人PTH 1 R基因均含有4个5'端非编码外显子（U1、U2、U3和U4）和3个启动子区。外显子U1上游的TATA样启动子称为P1启动子，外显子U3和U4上游的富含GC的启动子分别称为P2和P3启动子。在大鼠成骨细胞中，下游启动子（P2）在骨、肾等多种组织中有活性，而上游启动子（P1）具有组织特异性，在肾、卵巢等组织中有活性。研究结果如下：1.的GC ...更多信息 位于大鼠PTH 1 R U3启动子-128/-2区的box（P2）作为增强子，可被SM探针取代，即Sp1和MAZ结合序列. ST 2细胞成骨分化12天后，PTH 1 R mRNA表达。在ST 2细胞中，Sp1和MAZ mRNA在成骨细胞分化的各个阶段（0天后）均有表达. Sp1 mRNA在所有组织中均有表达。PTH 1 R mRNA的表达模式与MAZ mRNA的表达模式不同.在UMR-106细胞中，通过敲低Sp1或Maz抑制PTH 1 R mRNA的表达.在UMR-106细胞中，PTH 1 R基因U3启动子的活性被Sp1的敲低所抑制. ST 2细胞成骨分化12天后，PTH 1 R mRNA表达。另一方面，osterix mRNA在ST 2细胞成骨分化8天后表达. PTH 1 R mRNA表达的组织分布模式与osterix mRNA表达的组织分布模式非常相似。在UMR-106细胞中，PTH 1 R mRNA的表达被osterix的敲低所抑制。在UMR-106细胞中，PTH 1 R基因U3启动子活性不受osterix敲低的抑制。少

Parathyroid hormone (PTH) and PTH related protein (PTHrP) exert their effects on bone metabolism by binding to the G protein-coupled PTH/PTHrP receptor (PTH1R) expressed on osteoblasts. They increase expression one of the osteoclast activating factor (RANKL) and enhance bone resorption.The rat, mouse and human PTH1R genes contain four 5' noncoding exons (U1, U2, U3 and U4) and three promoter regions. A TATA-like promoter upstream of exon U1 is referred to as the P1 promoter and a GC-rich promoter upstream of exon U3 and U4 is called the P2 and P3 promoters respectively. In rats, the downstream promoter (P2) was active in a variety of tissues including bone and kidney, while the upstream promoter (P1) was tissue-specific, showing activity in the kidney and the ovary.In the present study, we attempted to analyze the mechanism of transcription related factor(s) and transcription enhancing factors on the promoter P2 of the PTH1R in the rat osteoblasts. The results were as follows.1. The GC … More box located in the -128/-2 region in the rat PTH1R U3 promoter (P2) was performed as an enhancer and could be replaced by the SM probe that was known as Sp1 and MAZ binding sequence.2. The PTH1R mRNA expressed after 12-day of osteoblastic differentiation in ST2 cells. On the other hands, both Sp1 and MAZ mRNA expressed in all period of osteoblastic differentiation (after 0-day) in ST2 cells.3. The Sp1 mRNA expressed in all tissues examined. A pattern of PTH1R mRNA expression was quite different from that of MAZ mRNA expression.4. The PTH1R mRNA expression was suppressed by a knockdown of Sp1 or Maz in UMR-106 cells.5. The PTH1R gene U3 promoter activities were suppressed by a knockdown of Sp1 in UMR-106 cells.6. The PTH1R mRNA expressed after 12-day of osteoblastic differentiation in ST2 cells. On the other hands, osterix mRNA expressed after 8-day of osteoblastic differentiation in ST2 cells.7. A pattern of tissue distribution of PTH1R mRNA expression was quite similar to that of osterix mRNA expression.8. The PTH1R mRNA expression was suppressed by a knockdown of osterix in UMR-106 cells.9. The PTH1R gene U3 promoter activities were not suppressed by a knockdown of osterix in UMR-106 cells. Less