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DSPP Function, Pathophysiology, and Genetic Diagnosis

DSPP 功能、病理生理学和遗传诊断

基本信息

批准号：
10448405
负责人：
JAMES P SIMMER
金额：
$ 47.51万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2024-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10448405
关键词：
Affect Algorithms Amino Acids C-terminal COL1A1 gene COL1A2 gene Cells Cellular Stress Clinical Collagen Gene Collagen Type I DSPP gene Defect Dental Dental Enamel Dentin Dentin Dysplasia Dentin Formation Dentinogenesis Dentinogenesis Imperfecta Diagnosis Disease Dominant-Negative Mutation Endoplasmic Reticulum Etiology Family Fracture Frameshift Mutation Functional disorder Gene Mutation Genes Genetic Goals Growth Health Human Incisor Individual Inheritance Patterns Inherited Ions Knock-in Mouse Knockout Mice Label Life Mandible Measures Mediating Medical Methods Minerals Mus Mutation Odontoblasts Organelles Osteogenesis Imperfecta Pathologic Pathology Patients Pattern Persons Pharmacology Phenotype Process Proteins Protocols documentation Reporting Reproducibility Research Resolution Risk Role Scanning Electron Microscopy Symptoms Syndrome Testing Therapeutic Time Tooth structure Toxic effect adduct bone bone fragility causal variant clinical phenotype disease-causing mutation endoplasmic reticulum stress gain of function genetic disorder diagnosis genetic testing human disease improved in vivo in vivo evaluation malformation microscopic imaging mineralization mouse model mutant recruit response

项目摘要

Hereditary Dentin Defects (HDD) affect 1 in 8,000 people. The genetic causes of most HDD correlate with the dysfunction of dentin proteins: type I collagen and dentin sialophosphoprotein (DSPP). All DSPP mutations reported to date show a dominant pattern of inheritance. This is because DSPP mutations manifest their phenotype through a dominant negative or gain of function mechanism—not by haplo- insufficiency. Reducing the normal amount of DSPP by half, as in Dspp heterozygous mice, does not cause dentin malformations. Dspp-/- null mice show a severe phenotype due to the absence of DSPP—not by the autosomal dominant pathological mechanism that causes HDD in humans. This distinction is important. Therapeutically, HDD in the absence of Dspp-/- could be reversed by restoring DSPP expression, whereas human HDD caused by DSPP mutations could not be restored in this way because the condition is not due to a lack of DSPP protein, but rather, is due to the pathological effects of aberrant DSPP in odontoblasts. This proposal “DSPP Function, Pathophysiology, and Genetic Diagnosis” seeks to improve our under- standings of 1) DSPP-derived proteins during normal dentinogenesis, 2) the pathological mechanism of Dspp -1 frameshift mutations, and 3) to develop a practical approach for HDD genetic testing to specifically identify the causative mutation and establish a definitive diagnosis. Three Specific Aims are proposed: SA1: Determine the role of DSPP-derived proteins during initial dentin mineral formation and coalescence by characterizing early dentin mineralization in Dspp+/+, Dspp-1fs/-1fs, Dspp-2fs/-2fs and Dspp-/- mice. SA2: Localize the DSPP -1 frameshift protein in vivo to determine where it accumulates and causes odontoblast cell pathology. SA3: Improve the diagnosis and management of HDDs by establishing an efficient genetic testing algorithm (sequence of actions that identifies the exact genetic cause of HDD in a given individual). Strategy: We hypothesize that DSPP helps initiate the mineralization of dentin calcospherites and promotes their growth and coalescence into a continuous mineral layer. By characterizing and comparing early dentin mineralization in Dspp+/+, Dspp-/-, and Dspp-2fs/-2fs mice using Focus Ion Beam Scanning Electron Microscopy (FIB-SEM), we can determine if dentin sialoprotein (DSP) or dentin phosphoprotein (DPP) is promoting the initiation and/or coalescence of dentin. We hypothesize that DSPP -1 frameshift mutations cause odontoblast cell pathology, possibly through ER stress. We test this hypothesis using Dspp -1 frameshift knockin mice that closely mimic human disease. Odontoblast pathology is assessed by FIB-SEM and TEM double immunogold labeling for the mutant protein and organelle markers in vivo. To improve the diagnosis and management of HDD, we apply a genetic testing algorithm to recruited HDD families to optimize its reproducibility and efficiency in identifying the underlying disease-causing mutations.

遗传性牙本质缺陷(HDD)影响每8,000人中就有1人。大多数HDD的遗传原因与牙本质蛋白功能障碍：I型胶原和牙本质涎磷蛋白(DSPP)。所有DSPP 到目前为止报道的突变显示了一种占主导地位的遗传模式。这是因为DSPP突变通过显性的负性或获得性作用机制--而不是单倍体--来表现它们的表型不够用。将DSPP的正常量减半，就像Dspp杂合子小鼠一样，不会导致牙本质畸形。DSPP-/-缺失的小鼠由于缺乏DSPP而表现出严重的表型--不是由常染色体显性致病机制在人类中引起。这一区别很重要。在治疗上，缺乏DSPP-/-的HDD可以通过恢复DSPP的表达来逆转，而由DSPP突变引起的人类HDD不能以这种方式恢复，因为这种情况不是由于这是由于缺乏DSPP蛋白，而是由于成牙本质细胞中异常的DSPP的病理效应所致。这项名为“DSPP功能、病理生理学和基因诊断”的建议旨在改善我们的 DSPP衍生蛋白在正常牙本质形成过程中的地位，2)牙本质形成的病理机制 DSPP-1移码突变，以及3)开发一种实用的HDD基因检测方法，以特定确定致病突变，并建立明确的诊断。提出了三个具体目标： SA1：确定DSPP衍生蛋白在牙本质矿物质形成和结合过程中的作用通过研究Dspp+/+、Dspp-1fs/-1fs、Dspp-2fs/-2fs和Dspp-/-小鼠早期牙本质矿化的特征。 SA2：在体内定位DSPP-1移码蛋白以确定它在哪里积累和导致成牙本质细胞病理学。 SA3：通过建立有效的基因检测来改进HDD的诊断和管理算法(确定特定个体中HDD的确切遗传原因的操作序列)。策略：我们假设DSPP有助于启动牙本质钙球的矿化和促进它们的生长和结合成一个连续的矿物层。通过刻画和比较聚焦离子束扫描研究Dspp+/+、Dspp-/-和Dspp-2fs/-2fs小鼠早期牙本质矿化电子显微镜(FIB-SEM)，我们可以确定牙本质唾液蛋白(DSP)或牙本质磷蛋白 (DPP)正在促进牙本质的起始和/或结合。我们假设DSPP-1的移码突变可能通过内质网应激引起成牙本质细胞的病理改变。我们使用以下工具来检验这一假设 Dspp-1基因移码敲击小鼠，与人类疾病非常相似。成牙本质细胞病理通过以下方法评估体内突变蛋白和细胞器标志物的FIB-SEM和TEM双重免疫金标记法。至改进HDD的诊断和管理，我们将遗传检测算法应用于招募的HDD 以优化其在识别潜在致病突变方面的重复性和效率。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

FAM20A mutations and transcriptome analyses of dental pulp tissues of enamel renal syndrome.

釉质肾综合征牙髓组织 FAM20A 突变及转录组分析

DOI：
10.1111/iej.13928
发表时间：
2023
期刊：
International endodontic journal
影响因子：
5
作者：
Wang,Shih-Kai;Zhang,Hong;Wang,Yin-Lin;Lin,Hung-Ying;Seymen,Figen;Koruyucu,Mine;Wright,JTimothy;Kim,Jung-Wook;Simmer,JamesP;Hu,JanC-C
通讯作者：
Hu,JanC-C

The Modified Shields Classification and 12 Families with Defined DSPP Mutations.

DOI：
10.3390/genes13050858
发表时间：
2022-05-12
期刊：
Genes
影响因子：
3.5
作者：
通讯作者：

Mouse Dspp frameshift model of human dentinogenesis imperfecta.

DOI：
10.1038/s41598-021-00219-4
发表时间：
2021-10-19
期刊：
Scientific reports
影响因子：
4.6
作者：
Liang T;Hu Y;Zhang H;Xu Q;Smith CE;Zhang C;Kim JW;Wang SK;Saunders TL;Lu Y;Hu JC;Simmer JP
通讯作者：
Simmer JP