PTHrP Function in the Periosteum and Entheses

描述(申请人提供)：我们已经创造了一个等位基因PTHrP-LacZ敲击小鼠，它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。这只小鼠的一个新发现是丰富的PTHrP/？半乳糖苷酶在骨膜中的表达。另一种是PTHrP在肌肉-骨膜附着部位、纤维肌腱和韧带附着部位、纤维软骨性肌腱附着部位大量表达。本提案包括三个具体目标，旨在启动对这些部位甲状旁腺素受体功能的研究。目的1.我们将研究PTHrP、PPR和细胞标记物在选定的骨膜部位和末端的表达，以便a)确定参与这些部位及其邻近部位旁分泌信号的细胞，b)加强我们对这些部位潜在的PTHrP功能的描述，以及c)实现目标2和3中提出的功能实验。目的2.在这里，我们提出两个子目标，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作用力对PTHrP表达的调节。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同位生长及其对PTHrP表达的影响；2)评价骨膜张力对PTHrP表达和同位生长的潜在影响。包膜亚目标包括三个实验，目的是加载或卸载选定的包膜，以测试机械力与这些部位PTHrP表达的关系。这些方法包括a)PTHrP-LacZ杂交到患有肌肉营养不良或肌肉抑制素缺乏的小鼠品系，分别代表肌肉质量显著减少或增加的模型，以及b)坐骨神经切除和c)尾部悬吊作为卸载技术。目的3.我们将使用小鼠Periostin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/? 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.