Identification of transcription enhancing fator for PTH receptor and analysis it's mechanism at jaw bone resorption site by oral cancer

甲状旁腺激素（PTH）和PTH相关蛋白（PTHrP）通过与成骨细胞中表达的G蛋白偶联的PTH/PTHrP受体（PTH1R）结合而影响骨代谢。它们增加破骨细胞激活因子（RANKL）的表达，促进骨吸收。大鼠、小鼠和人类PTH1R基因包含4个5'非编码外显子（Ul、U2、U3和U4）和3个启动子区域。外显子Ul上游的tata样启动子称为P1启动子，外显子U3和U4上游的GCrich启动子分别称为P2和P3启动子。在大鼠中，下游启动子（P2）在包括骨和肾在内的多种组织中都有活性，而上游启动子（P1）是组织特异性的，在肾脏和卵巢中显示活性。在本研究中，我们试图分析大鼠成骨细胞中PTH1R启动子P2转录相关因子的作用机制及其在口腔癌颌骨吸收部位的作用机制。U3启动子（P2）的核心启动子区（-128/+103）由三个重要部分组成。(1) PTHSR中的+1/+12区（+11+25）起引发子（Inr）的作用。(2) -128/-1区域是受MAZ和/或Sp1影响的激活剂结合域。(3) +51/+103区域是下游启动子元件。U3启动子中的Inr元件被特异性蛋白识别。PTH或igf - 1治疗降低了该复合物的稳定性，并减弱了pth1r .3的转录活性。亲和纯化结果表明，能与PTHSR区结合的候选蛋白为112和/或129 kDa蛋白。在几乎所有软口腔癌组织中，PTHrP的表达均明显高于正常组织。在PTI-IrP高表达癌组织附近的颌部，其中一种候选蛋白的表达不降低，但PTH1 R的表达下调。骨代谢指标RANKL、Cathepsin K升高，OPG略有下降。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 of the osteoclast activating factor (RANKL) and enhance bone resorption.The rat, mouse and human PTH1R genes contain four 5' noncoding exons (Ul, U2, U3 and U4) and three promoter regions. A TATA-like promoter upstream of exon Ul is referred to as the P1 promoter and a GCrich 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) on the promoter P2 of the PTH1R in the rat osteoblasts and their mechanism at jaw bone resorption site by oral cancer.1.The core promo … More ter region (-128/+103) of the U3 promoter (P2) was composed of three important parts.(1)The +1/+12 region in the PTHSR (+11+25) fanctioned as an initiator (Inr) element. (2) The -128/-1 region fanctioned as an activator binding domain affected by MAZ and/or Sp1. (3) The +51/+103 region fanctioned as a downstream promoter element.2.The Inr element in the U3 promoter was recognized by specific protein(s). The PTH or IGF-I treatment decreased stability of that complex and attenuated the transcription activity ofPTH1R.3.Affinity purification revealed that the candidate protein(s) could bind to the PTHSR region were 112 and/or 129 kDa protein(s).4.In almost all of soft oral cancer tissues, the PTHrP expression markedly increased compared with the normal part. In the jaws adjacent to cancer tissues with high expression of PTI-IrP, one of the candidate protein expression did not decrease, but the PTH1 R expression downregulated. The bone metabolism marker such as RANKL and Cathepsin K were increased and OPG slightly decreased in this situation. Less