PTHrP Function in the Periosteum and Entheses

描述（由申请人提供）：我们已经创建了等位基因PTHrP-lacZ敲入小鼠，其提供了在多种位置中PTHrP基因表达的简单且高灵敏度的读数。一个新的发现，在这只老鼠是丰富的PTHrP/？半乳糖苷酶在骨膜中的表达。另一种是在肌肉-骨膜附着点、纤维肌腱和韧带附着点以及纤维软骨肌腱附着点中PTHrP表达丰富。本提案包括三个具体目标，旨在启动PTHrP功能在这些网站的研究。目标1。我们将表征选定骨膜部位和附着点中的PTHrP、PPR和细胞标志物表达，以a）鉴定这些部位及其邻近部位中参与旁分泌信号传导的细胞，B）增强我们对这些部位中潜在PTHrP功能的描述性评价，以及c）实现目标2和3中提出的功能实验。目标2.在这里，我们提出了两个subaims，一个旨在研究PTHrP的影响和基因调控的骨膜和第二个研究PTHrP的表达在附着点的机械力推定的调节。骨膜子目标包括两个实验设计，包括1）骨膜附着生长的操作及其通过生长激素或生长激素受体拮抗剂对PTHrP表达的推定影响，以及2）评价骨膜张力对PTHrP表达和附着生长的潜在影响。附着点子目标包括设计用于加载或卸载选定附着点的三个实验，以测试这些位点中机械力与PTHrP表达之间的关系。这些包括a）PTHrP-lacZ与具有肌营养不良或肌生长抑制素缺乏的小鼠系杂交，其分别代表具有显著减少或增加的肌肉质量的模型，和B）坐骨神经切除术和c）尾部悬吊作为卸载技术。目标3.我们将使用小鼠骨膜蛋白基因启动子驱动Cre，在骨膜和选定的肌腱和韧带靶点中进行PTHrP信号传导的条件性敲除。

DESCRIPTION (provided by applicant): We have created an allelic PTHrP-lacZ knockin mouse that provides a simple and high-sensitivity readout of PTHrP gene expression in a wide variety of locations. One novel finding in this mouse is abundant PTHrP/? galactosidase expression in the periosteum. Another is abundant PTHrP expression in muscle-periosteal insertion sites, fibrous tendon and ligament insertion sites, and fibrocartilagenous tendon insertion sites. The present proposal comprises three specific aims designed to initiate studies of PTHrP function in these sites. Aim 1. We will characterize PTHrP, PPR and cell marker expression in selected periosteal sites and entheses in order to a) identify the cells that participate in paracrine signaling in these sites as well as their neighbors, b) enhance our descriptive appreciation of potential PTHrP functions in these sites, and c) enable the functional experiments proposed in Aim 2 and 3. Aim 2. Here, we propose two subaims, one designed to study PTHrP effects and gene regulation in the periosteum and the second to study the putative regulation of PTHrP expression in entheses by mechanical force. The periosteal subaim comprises two experimental designs, including 1) manipulation of periosteal appositional growth and it putative effects on PTHrP expression via growth hormone or a growth hormone receptor antagonist and 2) evaluating the potential effects of periosteal tension on PTHrP expression and appositional growth. The enthesis subaim comprises three experiments designed to load or unload selected entheses in order to test the relationship between mechanical force and PTHrP expression in these sites. These include a) PTHrP-lacZ crosses to mouse lines with muscular dystrophy or myostatin deficiency that represent models with markedly decreased or increased muscle mass, respectively, and b) sciatic neurectomy and c) tail suspension as unloading techniques. Aim 3. We will perform a conditional knockout of PTHrP signaling in the periosteum and selected tendon and ligament targets using the mouse periostin gene promoter to drive Cre.