BIOCHEMICAL STUDIES OF MINERALIZED TISSUE PROTEOGLYCANS

本继续申请旨在了解如何 骨的细胞外基质影响骨的形成和吸收。 申请人提出骨桥蛋白和蛋白多糖控制骨骼 形成和吸收。 磷酸化、硫酸化和共价交联化的变化 这些骨基质蛋白可能会改变这些蛋白的功能 在骨骼基质中。最近公布的证据表明，这块骨头 基质蛋白可能在破骨细胞和成骨细胞中发挥重要作用 功能，包括骨细胞对细胞的黏附特性 羟基磷灰石。提出了四个具体目标：第一，分析 不同磷酸化程度的骨桥蛋白对胰岛素的影响 体外羟基磷灰石的形成和生长；第二，评价能力 骨化三醇改变骨桥蛋白的表达和磷酸化。这 包括探索两种骨化三醇的基因组和非基因组作用 骨桥蛋白表达的衍生物和翻译后修饰； 第三，鉴定骨桥蛋白中的谷氨酰胺残留量 转谷氨酰胺酶活性，并确定骨细胞是否含有 谷氨酰胺转氨酶活性；第四，评估 磷酸化和非磷酸化形式的骨桥蛋白介导骨 细胞黏附和功能。

This continuation application is directed towards an understanding of how extracellular matrix of bone influences bone formation and resorption. The applicant proposes that osteopontin and proteoglycans control bone formation and resorption. Alterations in phosphorylation, sulfation and covalent crosslinking of these bone matrix proteins may modify the function of these proteins within the bone matrix. Recent published evidence indicates that the bone matrix proteins may have substantial roles in osteoclast and osteoblast function, including the cell adhesion properties of bone cells to hydroxyapatite. Four specific aims are proposed; first, to assay osteopontin of differing degrees of phosphorylation for effects on in vitro hydroxyapatite formation and growth; second, to evaluate the ability of calcitriol to alter osteopontin expression and phosphorylation. This includes exploring the genomic and nongenomic actions of two calcitriol derivatives on osteopontin expression and post- translation modifications; third, to identify glutamine residues in osteopontin that are substrates for transglutaminase activity and determine if bone cells contain transglutaminase activity; and fourth, to evaluate the role of phosphorylated and nonphosphorlyated forms of osteopontin to mediate bone cell adhesion and function.