Role of PI3 Kinase p110alpha in Osteoclasts

描述(申请人提供)：破骨细胞功能障碍导致病理性骨丢失，相关疾病包括类风湿性关节炎、牙周病、骨质疏松症和转移性骨肿瘤。被称为磷脂酰肌醇3-激酶(PI-3-Kinase)的一组酶的信号转导是调节破骨细胞性骨吸收的关键。破骨细胞表达三种不同类型的PI3-激酶。这些类别在结构、底物专一性和靶向元件上有所不同。它们被认为扮演着不同的生理角色，尽管这些划分尚不清楚。到目前为止，关于每种类型的PI 3-激酶在破骨细胞中的确切作用的数据很少。这项研究的中心假设是PI3-激酶在破骨细胞中具有不同的调节作用。基于腺相关病毒(AAV)的基因转移技术已在成熟的破骨细胞中表达了I型PI 3-激酶亚类(p110α)的一个亚类的有效反义。目前的提案有三个具体目标。首先，将确认p110α基因敲除的范围和特异性。如有必要，将采用更多的击倒方法。其次，研究p110α基因表达下调对细胞骨架组织、细胞极性、破骨细胞数量和骨吸收的影响。最后，下调p110α的表达对破骨细胞存活和凋亡的影响将被确定。综上所述，通过下调p110α的表达，并利用破骨细胞的发育、活性和存活的检测来表征其影响，我们应该能够为该酶指定特定的角色。这些研究可能导致新的、特定的、具有改善牙齿健康潜力的骨活性药物的开发。

DESCRIPTION (provided by applicant): Dysfunction of osteoclasts leads to pathological bone loss associated with diseases including rheumatoid arthritis, periodontal disease, osteoporosis and metastatic bone tumors. Signal transduction by a group of enzymes called phosphatidylinositol 3-kinases (PI 3-kinases) is known to be crucial for regulating osteoclastic bone resorption. Members of three distinct classes of PI 3-kinase are expressed in osteoclasts. The classes differ in structure, substrate specificity and targeting elements. They are thought to play distinct physiologic roles, although these divisions are not yet clear. To date, few data are available about the precise role of each type of PI 3-kinase in osteoclasts. The central hypothesis of this study is that the PI 3-kinases have non-identical regulatory roles in osteoclasts. An effective antisense to an isoform of a subclass of the class I PI 3-kinase (p110alpha) has been expressed in mature osteoclasts by adeno-associated virus (AAV) based gene transfer techniques. The current proposal has three specific Aims. First, the extent and specificity of the p110alpha knock down will be confirmed. If necessary, additional knockdown approaches will be utilized. Second, the effects of knocking down expression of p110alpha on cytoskeletal organization, cell polarity, osteoclast number and bone resorption will be examined. Finally, the effects of knocking down expression of p110alpha on osteoclast survival and apoptosis will be determined. In summary, by knocking down expression of p110alpha and characterizing the effects using assays for the development, activity and survival of osteoclasts, we should be able to assign specific roles for this enzyme. These studies could lead to the development of new, specific, bone active pharmaceuticals with the potential to improve dental health.