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，破骨细胞是一种源自髓系造血前体细胞的细胞类型。破骨细胞的发育需要激活破骨前细胞上的细胞表面受体，绝对需要刺激RANK （NFkappa b激活受体）和c-fms（巨噬细胞集落刺激因子受体，M-CSF）。其他影响破骨细胞发育和功能的免疫调节受体尚不清楚。其他人和我们最近证明了一个新的受体家族在破骨细胞中的表达和功能，即dap12相关受体。在我们的前期工作中，我们证明了DAP12和DAP12相关受体存在于破骨前细胞和破骨细胞中，并表明从DAP12 -/-小鼠体外培养的破骨细胞在破骨细胞发育中存在缺陷，骨吸收减少。在体内，DAP12 -/-小鼠的胫骨骨量增加。DAP12相关受体通过其与信号转导蛋白DAP12 （DNAX转导蛋白12）的功能关联来定义，并介导其他髓系细胞（巨噬细胞和树突状细胞）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基因功能丧失有关。plsl患者在30岁前有多发骨囊肿、病理性骨折和严重关节炎。最近的研究表明，来自PLOSL患者的细胞在体外表现出异常的破骨细胞发育，与我们在DAP12 -/-小鼠中的观察结果相似。

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.