DAP-12 ASSOCIATED RECEPTORS IN OSTEOCLASTS

描述(申请人提供)：骨吸收是破骨细胞的独特功能，破骨细胞是一种来源于髓系造血祖细胞的细胞类型。破骨细胞的发育需要破骨前细胞表面受体的激活，绝对需要RANK(激活NFkappa b的受体)和c-FMS(巨噬细胞集落刺激因子受体，M-CSF)的刺激。其他影响破骨细胞发育和功能的免疫调节受体知之甚少。最近，我们展示了破骨细胞中一种新的受体家族的表达和功能，即DAP12相关受体。在我们的初步工作中，我们证明了DAP12和DAP12相关受体在破骨前细胞和破骨细胞中的存在，并表明从DAP12-/-小鼠体外培养的破骨细胞在破骨细胞发育方面存在缺陷，骨吸收减少。在体内，DAP12-/-小鼠的胫骨显示骨量增加。DAP12相关受体由它们与信号转导蛋白DAP12(DNAX转接蛋白12)的功能结合来定义，并在其他髓系细胞(巨噬细胞和树突状细胞)中介导细胞的激活和成熟。我们建议P12在破骨细胞中扮演类似的角色。有趣的是，一种罕见的遗传性多囊性脂膜性骨发育不良伴硬化性白质脑病(PLOSL)涉及骨骼异常，与DAP12基因的功能丧失有关。PLOSL患者在30岁之前有多发性骨囊肿、病理性骨折和严重关节炎。最近的研究表明，PLOSL患者的细胞在体外显示出破骨细胞的异常发育，这与我们在DAP12-/-小鼠中观察到的情况类似。 我们的研究将进一步验证DAP12和DAP12相关受体(DAR)介导的信号调节破骨细胞的发育、激活和存活并在骨重建中发挥作用的假说。 具体目标： 1)检测DAP12和DAR激活对破骨细胞多核形成的影响 2)检测DAP12和DAR激活对破骨细胞功能的影响 3)检测DAP12和DAR激活对破骨细胞(OC)存活的影响 4)通过骨组织形态计量学和显微CT分析进一步检测DAP12-/-动物的骨表型，并检测其对不同骨吸收刺激的反应 5)研究DAP12信号对RANK信号中间产物和细胞骨架重排的影响。

DESCRIPTION (provided by applicant): Resorption of bone is the unique function of the osteoclast, a cell type derived from hematopoietic precursor cells in the myeloid lineage. Osteoclast development requires the activation of cell surface receptors on preosteoclasts, with an absolute requirement for stimulation of RANK (receptor for activation of NFkappa b) and c-fms (receptor for macrophage colony stimulating factor, M-CSF). Other immunomodulatory receptors that influence osteoclast development and function are less well understood. Others and we have recently demonstrated expression and function of a novel family of receptors in osteoclasts, the DAP12-associated receptors. In our preliminary work, we demonstrate the presence of DAP12 and DAP12 associated receptors in preosteoclasts and osteoclasts and show that osteoclasts developed in vitro from DAP12 -/- mice are defective in osteoclast development with decreased bone resorption. In vivo, the tibias of DAP12 -/-mice show increased bone mass. DAP12-associated receptors are defined by their functional association with the signaling adapter protein DAP12 (DNAX adapter protein 12) and mediate cellular activation and maturation in other myeloid lineage cells (macrophages and dendritic cells). We suggest a similar role for P12 in osteoclasts. Interestingly, a rare inherited human disease Polycystic Lipomembranous Osteodysplasia with Sclerosing Leukoencephalopathy (PLOSL) involving bony abnormalities is associated with loss of function of the DAP12 gene. PLOSL patients have multiple bony cysts, pathological fractures and severe arthritis before age 30. Recent studies have shown that cells from PLOSL patients show abnormal in vitro osteoclast development similar to our observations in DAP12 -/-mice. Our studies will further examine the hypothesis that signals mediated by DAP12 and DAP12-associated receptors (DAR) regulate the development, activation and survival of osteoclasts and play a role in bony remodeling. Specific Aims: 1) Examine the effect of DAP12 and DAR activation on osteoclast (OC) multinucleation 2) Examine the effect of DAP12 and DAR activation on osteoclast function 3) Examine the effect of DAP12 and DAR activation on osteoclast (OC) survival 4) Further examine the bony phenotype of DAP12-/- animals by bone histomorphometry and microCT analysis and examine the response to distinct bone resorptive stimuli 5) Examine the effect of DAP12 signals on RANK signaling intermediates and cytoskeletal rearrangement.