Studies of the Roles of DMP1 and DSPP in Osteogenesis and Dentinogenesis

DMP1和DSPP在成骨和牙本质形成中的作用研究

基本信息

批准号：
8035597
负责人：
Chunlin Qin
金额：
$ 7.23万
依托单位：
TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
依托单位国家：
美国
项目类别：
财政年份：
1997
资助国家：
美国
起止时间：
1997-07-01 至 2010-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8035597
关键词：
Ablation Affect Biochemical Biological Process Categories Cells Cleaved cell Collagen Type I Core Protein DSPP gene Data Defect Dental Dentin Dentin Formation Dentinogenesis Dentinogenesis Imperfecta Disease Eukaryotic Cell Event Extracellular Matrix Extracellular Matrix Proteins Failure Family Family member Gene Cluster Genes Genetic Glycosaminoglycans Grant Human Human Genetics In Vitro Inborn Genetic Diseases Knockout Mice Knowledge Lead Length Modality Molecular Mus Mutant Strains Mice Mutation N-terminal Odontoblasts Osteoblasts Osteogenesis Osteoid Osteomalacia Osteoporosis Pathogenesis Pathway interactions Peptide Hydrolases Peptides Phenotype Physiologic calcification Play Post-Translational Protein Processing Process Proteins Proteoglycan Proteolytic Processing Research Rickets Role Series Siblings Side Site Skeleton Solid Structure Systemic disease Testing Time Tissues Work base biomineralization bone craniofacial complex dentin matrix protein 1 design in vivo innovation insight member mineralization mouse Dspp protein public health relevance research study skeletal disorder

项目摘要

DESCRIPTION (provided by applicant): The research proposed in this competing grant renewal focuses on dentin matrix protein 1 (DMP1) and dentin sialophosphoprotein (DSPP), two non-collagenous extracellular matrix (ECM) proteins that belong to the SIBLING family. The importance of DMP1 and DSPP in biomineralization has been demonstrated by studies showing that humans or mice with altered Dmp1 or Dspp gene display defects in the mineralization of bone and/or dentin. Although solid data have demonstrated the association between these two proteins and the formation of healthy bone and/or dentin, the specific mechanistic pathways by which DMP1 and DSPP participate in osteogenesis and dentinogenesis remain ill-defined. Studies proposed in this application are aimed to test how posttranslational proteolytic processing of DMP1 and DSPP affects the mineralization of bone and/or dentin. The following data from our independent and collaborative studies have established that DMP1 and DSPP undergo proteolytic processing and that posttranslational processing may be essential for the mineralization of bone and/or dentin. Our findings include: 1) DMP1 and DSPP are present in the ECM of bone and dentin as NH2-terminal and COOH-terminal fragments. 2) Proteolytic processing of DMP1 and DSPP involves cleavage of peptide bonds at the NH2-termini of aspartyl residues (i.e., at X-Asp bonds). 3) The highly glycosylated NH2-terminal fragments of DMP1 and DSPP have biochemical features distinct from those of their respective COOH-terminal fragments. 4) The highly phosphorylated COOH-terminal fragments of DMP1 and DSPP promote mineralization in vitro. 5) Substitution of an aspartyl residue at a cleavage site blocks the proteolytic processing of DMP1 in transfected eukaryotic cells. 6) Re-expression of the COOH-terminal fragment of DMP1 is capable of rescuing the mineralization defects in Dmp1-null mice. 7) The NH2-terminal fragment and COOH-terminal fragment of DMP1 show clear difference in tissue localization. We hypothesize that proteolytic processing of DMP1 and DSPP by cleavage of selected X-Asp bonds is an activation step that converts precursors from inactive forms to fragments that are fully active at the correct time and site to control the mineralization process. These processing events play crucial roles in the mechanisms that control the conversion of osteoid to bone and predentin to dentin. Hence, failure to process these two proteins will lead to abnormal bone and/or dentin formation. To test the above hypothesis, we propose a series of studies to determine if failure to process these two proteins due to substitution of Asp residues at key cleavage sites will result in the loss of DMP1 or DSPP functions in vivo, and to characterize the roles of the COOH-terminal fragment and NH2-termnial fragment of DSPP. The proposed studies are expected to unfold greater understanding of the process controlling osteogenesis and dentinogenesis. PUBLIC HEALTH RELEVANCE: Fundamental information about how DMP1 and DSPP affect the formation of bone and dentin is essential to enhanced understanding concerning the pathogeneses of bony and dental defects associated with systemic diseases such as osteomalacia, osteoporosis and dentinogenesis imperfecta. Results of the studies proposed in this application will unfold greater understanding of the mechanisms controlling the mineralization of bone and dentin, thus proving information needed for delineating the pathogeneses underlying these bony and dental defects and for establishing scientifically based treatment modalities for such skeletal diseases.

描述（由申请人提供）：在此竞争授予续签中提出的研究重点介绍了牙本质基质蛋白1（DMP1）和牙本质sialophophophoponin（DSPP），这是两个非胶质细胞外基质（ECM）蛋白，这些蛋白质属于sibling家族。 DMP1和DSPP在生物矿化中的重要性已经证明了DMP1或DSPP基因改变的人或小鼠在骨骼和/或牙本质的矿化中显示出缺陷。尽管固体数据证明了这两种蛋白质与健康骨和/或牙本质的形成之间的关联，但DMP1和DSPP参与骨生成的特定机械途径和牙齿发生仍然不确定。该应用中提出的研究旨在测试DMP1和DSPP的翻译后蛋白水解处理如何影响骨骼和/或牙本质的矿化。来自我们独立和协作研究的以下数据已经确定，DMP1和DSPP经历蛋白水解处理，并且翻译后处理对于骨骼和/或牙本质的矿化可能至关重要。我们的发现包括：1）DMP1和DSPP存在于骨骼和牙本质中，作为NH2末端和COOH末端片段。 2）DMP1和DSPP的蛋白水解加工涉及在体育基残基的NH2-末端（即在X-ASP键）上裂解肽键。 3）DMP1和DSPP的高度糖基化的NH2末端片段具有与各自的COOH末端片段不同的生化特征。 4）DMP1和DSPP的高度磷酸化的COOH末端片段在体外促进矿化。 5）在裂解位点取代天冬氨酸残基会阻止转染的真核细胞中DMP1的蛋白水解处理。 6）DMP1的COOH末端片段的重新表达能够挽救DMP1-NULL小鼠中的矿化缺陷。 7）DMP1的NH2末端片段和COOH末端片段在组织定位方面显示出明显的差异。我们假设通过裂解选定的X-Asp键对DMP1和DSPP的蛋白水解处理是一个激活步骤，它将前体从非活动形式转换为在正确的时间和位点完全活跃的片段以控制矿化过程。这些加工事件在控制骨质骨转化为骨和牙本质的机制中起着至关重要的作用。因此，未能处理这两种蛋白质将导致异常的骨骼和/或牙本质形成。为了检验上述假设，我们提出了一系列研究，以确定由于在关键裂解位点取代ASP残基而未能处理这两种蛋白质是否会导致DMP1或DSPP在体内的功能丧失，并表征COOH末端片段和DSPP的NH2-Termnial fragment的作用。预计拟议的研究将对控制成骨的过程和牙本质生成的过程有更深入的了解。公共卫生相关性：有关DMP1和DSPP如何影响骨骼和牙本质形成的基本信息，对于增强与全身性疾病相关的骨质疾病，骨质疏松症，骨质疏松症和牙本质发生的理解至关重要。本应用中提出的研究的结果将展开对控制骨骼和牙本质矿化的机制的更多了解，从而证明了描述这些骨缺陷和牙齿缺陷的病原体所需的信息，并建立了基于科学的治疗方法来为此类骨架疾病。