MOLECULAR MECHANISMS OF MACROPHAGE MULTINUCLEATION

破骨细胞和多核巨细胞起源于融合 单核细胞-巨噬细胞谱系的单核前体。 多核化是其主要的表型特征之一 细胞 虽然核聚变是形成这些核的重要步骤， 细胞，它发生的分子机制，以及功能性 多核化的后果知之甚少。 破骨细胞和 巨细胞有一些相似之处，但显然是不同的细胞类型 并存在于不同的微环境中。 就他们 相似之处，我们已经表明，多核肺泡 巨噬细胞表达，像破骨细胞，高和极化， 质膜Na，K-ATP酶浓度以及高拷贝 降钙素受体的数量。 最重要的是， 最近证明，肺泡巨噬细胞，培养下 在适当的条件下，能够在体外再吸收骨。 在 在本申请中，我们提出使用巨噬细胞作为模型系统， 单核-巨噬细胞融合机制的研究 脉 为了研究细胞融合的机制，我们假设 多核体的形成必须依赖于细胞表面分子 特异于单核细胞-巨噬细胞。 在上一个资助期间，我们发现了巨噬细胞- 可能介导融合的特定表面分子。 我们有 产生的单克隆抗体，选择他们的能力， 体外巨噬细胞融合。 初步生化特征- 其中一种抗原的变性显示了一种表面糖蛋白 在巨噬细胞中特异性检测到， 核聚变 相似分子量的糖蛋白通过 我们还选择了另外三种单克隆抗体， 防止融合的能力。 这个项目的长期目标是阐明聚变机制 导致多核体的形成。 本申请的具体目的是： 1. 为了在分子水平上表征 由我们的单克隆抗体12 D 6、10 B11、10 C4和10 B12识别的抗原。 10 C5在体外阻断巨噬细胞融合。 这将是完成 通过克隆编码相应抗原的cDNA。 2. 建立一个合适的细胞表达系统， 分析这些抗原。 3. 探讨12 D 6抗原在破骨细胞和巨细胞中的作用 在体内形成，以及通过 影响破骨细胞分化。

Osteoclasts and multinucleated giant cells originate from the fusion of mononuclear precursors of the monocyte-macrophage lineage. Multinucleation is one of the main phenotypic characteristics of these cells. Although fusion is an essential step in formation of these cells, the molecular mechanisms by which it occurs, and the functional consequences of multinucleation are poorly understood. Osteoclast and giant cells share some similarities but are clearly distinct cell types and reside in different microenvironments. As far as their similarities are concerned, we have shown that multinucleated alveolar macrophages express, like osteoclasts, a high and polarized concentration of plasma membrane Na,K-ATPases as well as a high copy number of receptors for calcitonin. Most importantly, it has been recently demonstrated that alveolar macrophages, cultured under appropriate conditions, are capable of resorbing bone in vitro. In this application we propose to use macrophages as a model system to study the mechanism of fusion of cells of the monocyte- macrophage lineage. To investigate the mechanism of cell fusion, we hypothesize that the formation of polykaryons must depend upon cell surface molecules specific for monocyte-macrophages. During the previous funding period, we have identified macrophage- specific surface molecules which potentially mediate fusion. We have generated monoclonal antibodies selected for their ability to prevent fusion of macrophages in vitro. Preliminary biochemical character- ization of one of the antigens has revealed a surface glycoprotein which is specifically detected in macrophages at the time of their fusion. A glycoprotein of similar molecular weight is detected by three additional monoclonal antibodies which we also selected for their ability to prevent fusion. The long-term goal of this project is to elucidate the fusion mechanism of macrophages which leads to the formation of polykaryons. The SPECIFIC AIMS of the present application are: 1. To characterize at the molecular level the structure of the antigens recognized by our monoclonal antibodies 12D6, 10B11, 10C4 and 10C5 which block macrophage fusion in vitro. This will be accomplished by cloning cDNAs coding for the corresponding antigens. 2. To establish a suitable cell expression system for the functional analysis of these antigens. 3. To determine the role of 12D6 antigen in osteoclast and giant cell formation in vivo, and the regulation of its expression by agents that affect osteoclast differentiation.