PTHrP Function in the Periosteum and Entheses

描述（由申请人提供）：我们已经创建了一个等位基因PTHrP- lacz敲入小鼠，提供了一个简单和高灵敏度的PTHrP基因在各种位置的表达读数。该小鼠的一个新发现是骨膜中丰富的PTHrP/ β -半乳糖苷酶表达。另一种是PTHrP在肌骨膜止点、纤维肌腱和韧带止点、纤维软骨肌腱止点丰富表达。本建议包括三个具体目标，旨在开始研究这些地点的PTHrP功能。目的1。我们将在选定的骨膜部位和囊体中表征PTHrP、PPR和细胞标志物的表达，以便a)鉴定参与这些部位及其邻近部位旁分泌信号的细胞，b)增强我们对这些部位潜在PTHrP功能的描述性认识，c)实现第2和3部分提出的功能实验。目标2。在这里，我们提出了两个子目标，一个旨在研究PTHrP在骨膜中的作用和基因调控，第二个旨在研究机械力对PTHrP在血管中的表达的可能调控。骨膜亚目标包括两个实验设计，包括1)通过生长激素或生长激素受体拮抗剂操纵骨膜附着生长及其对PTHrP表达的可能影响，以及2)评估骨膜张力对PTHrP表达和附着生长的潜在影响。该实验包括三个实验，旨在加载或卸载选定的关节，以测试机械力与这些部位的PTHrP表达之间的关系。这些包括a) PTHrP-lacZ与肌肉萎缩或肌肉生长抑制素缺乏的小鼠系杂交，分别代表肌肉质量明显减少或增加的模型，b)坐骨神经切除术和c)尾部悬挂作为卸载技术。目标3。我们将使用小鼠骨膜蛋白基因启动子来驱动Cre，在骨膜和选定的肌腱和韧带靶点进行有条件的PTHrP信号敲除。

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/beta 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.