DAP-12 ASSOCIATED RECEPTORS IN OSTEOCLASTS

描述（由申请人提供）：骨吸收是破骨细胞的独特功能，破骨细胞是一种来源于骨髓系造血前体细胞的细胞类型。破骨细胞的发育需要前破骨细胞上的细胞表面受体的活化，绝对需要RANK（NF κ B活化受体）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还不太清楚。其他人和我们最近已经证明了破骨细胞中一个新的受体家族，DAP 12相关受体的表达和功能。在我们的初步工作中，我们证明了存在的DAP 12和DAP 12相关的受体在前破骨细胞和破骨细胞，并表明，破骨细胞在体外开发的DAP 12-/-小鼠是有缺陷的破骨细胞的发展与骨吸收减少。在体内，DAP 12-/-小鼠的胫骨显示出增加的骨量。DAP 12相关受体通过其与信号传导衔接蛋白DAP 12（DNAX衔接蛋白12）的功能关联来定义，并介导其他髓系细胞（巨噬细胞和树突细胞）中的细胞活化和成熟。我们认为P12在破骨细胞中也有类似的作用。有趣的是，一种罕见的遗传性人类疾病多囊脂膜性骨发育不良伴硬化性白质脑病（PLOSL）涉及骨骼异常，与DAP 12基因功能丧失有关。PLOSL患者在30岁之前有多个骨囊肿、病理性骨折和严重关节炎。最近的研究表明，来自PLOSL患者的细胞显示出与我们在DAP 12-/-小鼠中观察到的类似的体外破骨细胞发育异常。 我们的研究将进一步检验由DAP 12和DAP 12相关受体（DAR）介导的信号调节破骨细胞的发育、活化和存活并在骨重建中发挥作用的假设。 具体目标： 1)检查DAP 12和DAR活化对破骨细胞（OC）多核化的影响 2)检查DAP 12和DAR激活对破骨细胞功能的影响 3)检查DAP 12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microCT分析进一步检查DAP 12-/-动物的骨表型，并检查对不同骨吸收刺激的反应 5)检查DAP 12信号对RANK信号传导中间体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.