CARBOHYDRATE RECEPTORS IN OSTEOCLAST FUNCTION

在骨骼中，成骨细胞/破骨细胞的相互作用似乎是由 间接部分是通过细胞外基质的成分。至 控制细胞的形成、诱导、定位和激活 破骨细胞，成骨细胞可以通过 它们分泌和沉积在细胞外基质中的大分子或 骨样的。非胶原糖蛋白，即骨桥蛋白、骨 唾液蛋白、骨酸性糖蛋白-75、核心蛋白和二聚糖， 由成骨细胞合成并分泌形成骨基质 含有0-连接和/或N-连接的低聚糖链。然而， 这些翻译后修改对 破骨细胞的发育和功能尚未得到充分研究。 我们的假设是碳水化合物受体(凝集素或碳水化合物 识别域)在发展和功能中发挥作用 破骨细胞。我们将解决以下基本问题。目标1.做 体内多核破骨细胞表达碳水化合物受体 幼年大鼠骨及骨髓消融模型中的加速骨 营业额？骨髓消融模型允许分析不同的 骨转换的主要阶段，即破骨细胞富集期 10天，并产生可被分离的RNA或 剖切。考虑破骨细胞的共同干细胞来源 巨噬细胞/单核细胞，表达碳水化合物受体 在内吞作用或与基质的黏附中，以及克隆的可用性 受体cDNA，我们的方法将首先确定 破骨细胞共表达已知的巨噬细胞/枯否细胞凝集素 Northern杂交和原位杂交的应用。尽管数据来自 上世纪80年代中期的S则相反，破骨细胞和巨噬细胞样细胞 已被证明具有许多共同的抗原和丰富的 巨噬细胞/枯否细胞/白细胞碳水化合物受体的数据 出现在其间的时期。然而，如果Northern与 第二种方法是诱导骨不表达这些克隆的凝集素。 将被用来证明破骨细胞内/上的碳水化合物受体 在组织切片中通过直接结合和竞争 碳水化合物配体。这些替代方法应该会导致 回答目标1中提出的问题。 临床相关性：骨量和牙槽骨质量代表净值 持续的动态再吸收和形成过程的总和 在人类的整个生命中。所有个体都会经历骨质疏松症 年龄越来越大。当骨量达到临界阈值时，骨折 发生创伤小(骨质疏松症)。骨质疏松症是一大 美国的健康问题，据估计有2000万人 目前人们受到影响，130万人骨折 每年都要归因于它。虽然有有限的研究支持，但 科学文献表明骨质疏松症可能是 伴随着颅面骨的加速丢失；在识别中 对于这一事实，NLDR和NIAMSD在#年发起了一个研究计划 口腔骨丢失与骨质疏松。这项建议是一项新的调查 青年和成人破骨细胞糖受体表达的研究 诱导骨组织。如果存在，碳水化合物受体可以介导 的定位、依附、融合和吸收功能 骨骼上的破骨细胞。破骨细胞-基质识别机制是 治疗干预的首要目标。

In bone, osteoblast/osteoclast interactions appear to be mediated indirectly in part by components of the extracellular matrix. To control formation, induction, localization, and activation of osteoclasts, osteoblasts may transfer signals/messages via macromolecules they secrete and deposit in the extracellular matrix or osteoid. Non-collagenous glycoproteins, ie., osteopontin, bone sialoprotein, bone acidic glycoprotein-75, decorin, and biglycan, synthesized by osteoblasts and secreted into forming bone matrix contain 0-linked and/or N-linked oligosaccharide chains. However, the significance of these post-translational modifications to the development and function of osteoclasts has not been fully explored. Our hypothesis is that carbohydrate receptors (lectins or carbohydrate recognition domains) play a role in the development and function of osteoclasts. We will address the following basic question. AIM 1. Do multinucleated osteoclasts express carbohydrate receptors in vivo in young rat bone and in the marrow ablation model of accelerated bone turnover? The marrow ablation model permits an analysis of different predominant stages of bone turnover, ie., osteoclast rich phase at 8- 10 days, and yields induced bone amenable to isolation of RNA or sectioning. Considering a shared stem cell origin of osteoclasts with macrophage/ monocyte cells, which express carbohydrate receptors used in endocytosis or adhesion to matrices, and the availability of cloned receptor cDNAs, our approach will be to first determine whether osteoclasts co-express known macrophage/Kupffer cell lectins through use of Northern blotting and in situ hybridization. Despite data from the mid 1980's to the contrary, osteoclasts and macrophage-like cells have been shown to share a number of common antigens and a wealth of data on macrophage/Kupffer cell/leukocyte carbohydrate receptors has appeared in the intervening period. However, if Northern blots with induced bone are negative for these cloned lectins, a second approach will be taken to demonstrate carbohydrate receptors in/on osteoclasts in tissue sections through direct binding and competition with carbohydrate ligands. These alternate approaches should lead to an answer to the question posed in Aim 1. Clinical Relevance: Skeletal and alveolar bone mass represents the net sum of dynamic resorptive and formative processes which continue throughout life in humans. All individuals experience osteopenia with increasing age. When bone mass reaches a critical threshold, fractures occur with little trauma (osteoporosis). Osteoporosis is a major health problem in the U.S. where it is estimated that 20 million people are currently affected and 1.3 million fractures are attributable to it each year. While supported by limited research, the scientific literature suggests that skeletal osteopenia may be accompanied by accelerated loss of craniofacial bone; in recognition of this fact, NlDR and NIAMSD have initiated a Research Program in Oral Bone Loss and Osteoporosis. This proposal is a new investigation of carbohydrate receptor expression by osteoclasts in young and induced bone tissue. If present, carbohydrate receptors could mediate the localization, attachment, fusion, and resorptive function of osteoclasts on bone. Osteoclast-matrix recognition mechanisms are a prime target for therapeutic intervention.