Mineralization of the matrix in disease and health

疾病和健康中基质的矿化

• 批准号: 7088784
• 负责人: PETER S ROWE
• 金额: $ 31.58万
• 依托单位: UNIVERSITY OF KANSAS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-08 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7088784
• 关键词: X ray crystallography; cell free system; cell line; chemical cleavage; clinical research; extracellular matrix proteins; genetically modified animals; glycoproteins; human tissue; infrared spectrometry; laboratory mouse; laboratory rat; metalloendopeptidases; molecular biology; molecular pathology; neutralizing antibody; normal ossification; osteoblasts; osteomalacia; phosphoproteins; phosphorylation; protein protein interaction; protein structure function; proteolysis; recombinant proteins; surface plasmon resonance; synthetic peptide; vitamin D resistant rickets

DESCRIPTION (provided by applicant): Inherited and tumor acquired bone-mineral disorders have provided powerful models that have helped understand some of the molecular-mechanisms responsible for maintaining a healthy, dynamic, mineralized-skeleton. X-linked hypophosphatemic rickets (HYP) is one such disease and is associated with severe defects in mineralization, renal phosphate handling, and vitamin D metabolism. MEPE, (a bone-matrix protein) and osteoblastic-proteases are elevated markedly in HYP. Also, PHEX, an osteoblast-expressed, plasma-membrane anchored Zn-metallopeptidase is the primary defect responsible for the disease. We have substantive preliminary data that supports the hypothesis that a protein-protein interaction between MEPE and PHEX regulates mineralization. PHEX protects MEPE from proteolytic cleavage by proteases (notably cathepsin B) in-vitro and osteoblastic-proteases are elevated in Hyp. In the absence of PHEX, MEPE is cleaved, releasing a phosphorylated, acidic, serine-aspartate rich, C-terminal fragment (ASARM-peptide). The ASARM-peptide (2 kDa), is remarkably resistant to a vast array of proteases resulting in increased levels in Hyp. The ASARM-peptide inhibits mineralization and elevated ASARM-peptide is proposed to be wholly or in part responsible for the mineralization defects. This application will focus on the role of MEPE and ASARM-peptides in mineralization. Our specific aims are: 1. Structural characterization and quantification of MEPE ASARM-peptide(s) in-vitro and in-vivo in normal and Hyp osteoblasts and serum. 2. Determination of MEPE ASARM-peptide effects on mineralization in-vitro and in-vivo. 3. Elucidation of MEPE-PHEX protein-protein interactions. 4. The role of elevated protease(s) in Hyp-osteoblasts in relation to abnormal mineralization and MEPE-PHEX interactions. The ASARM-motif is present in a number of tooth-bone matrix and salivary proteins. These include MEPE, DMP1, osteopontin, statherin, DSPP that all map to chromosome 4q21. Thus, the elucidation of its role in mineralization is of prime importance for understanding bone mineralization mechanisms. Importantly, the part the motif plays will have relevance to the treatment and understanding of bone-fracture risk, osteoporosis, tumor-induced osteomalacia (OHO), HYP, periodontal disease, disorders of mineralization in teeth, bone, renal-stones and ectopic calcifications in arteries and renal-osteodystrophy.

描述（由申请人提供）： 遗传性和肿瘤获得性骨矿物质疾病提供了强大的模型，有助于理解一些负责维持健康、动态、矿化骨骼的分子机制。 X 连锁低磷血症性佝偻病 (HYP) 就是这样一种疾病，与矿化、肾脏磷酸盐处理和维生素 D 代谢的严重缺陷有关。 MEPE（一种骨基质蛋白）和成骨细胞蛋白酶在 HYP 中显着升高。此外，PHEX（一种成骨细胞表达的质膜锚定锌金属肽酶）是导致该疾病的主要缺陷。我们有大量的初步数据支持 MEPE 和 PHEX 之间的蛋白质-蛋白质相互作用调节矿化的假设。 PHEX 在体外保护 MEPE 免受蛋白酶（特别是组织蛋白酶 B）的蛋白水解切割，并且成骨细胞蛋白酶在 Hyp 中升高。在没有 PHEX 的情况下，MEPE 被裂解，释放出磷酸化、酸性、富含丝氨酸天冬氨酸的 C 端片段（ASARM 肽）。 ASARM 肽 (2 kDa) 对多种蛋白酶具有显着的抗性，导致 Hyp 水平升高。 ASARM 肽抑制矿化，并且升高的 ASARM 肽被认为是造成矿化缺陷的全部或部分原因。该应用将重点关注 MEPE 和 ASARM 肽在矿化中的作用。我们的具体目标是： 1. MEPE ASARM 肽在正常和 Hyp 成骨细胞和血清中的体外和体内结构表征和定量。 2. MEPE ASARM-肽对体外和体内矿化作用的测定。 3. MEPE-PHEX 蛋白质-蛋白质相互作用的阐明。 4. 成骨细胞中蛋白酶升高与异常矿化和 MEPE-PHEX 相互作用相关的作用。 ASARM 基序存在于许多牙骨基质和唾液蛋白中。这些包括 MEPE、DMP1、骨桥蛋白、statherin、DSPP，全部映射到染色体 4q21。因此，阐明其在矿化中的作用对于理解骨矿化机制至关重要。重要的是，该主题所发挥的作用将与骨折风险、骨质疏松症、肿瘤诱发的骨软化症（OHO）、HYP、牙周病、牙齿、骨、肾结石和动脉异位钙化以及肾性骨营养不良的矿化障碍的治疗和理解相关。