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 的遗传原因与遗传性牙本质缺陷有关。牙本质蛋白的功能障碍：I型胶原蛋白和牙本质唾液酸磷蛋白（DSPP）。迄今为止报道的突变显示出显性遗传模式，这是因为 DSPP 突变。他们的表型通过显性失活或功能增强机制表现出来，而不是通过单倍体将 DSPP 的正常量减少一半（如 Dspp 杂合小鼠）不会导致缺乏。 Dspp-/- 缺失小鼠表现出严重的表型，这是由于 DSPP 的缺失，而不是由导致人类 HDD 的常染色体显性病理机制这一区别很重要。在治疗上，缺乏 Dspp-/- 的 HDD 可以通过恢复 DSPP 表达来逆转，而 DSPP突变引起的人类HDD无法通过这种方式恢复，因为条件不合适 DSPP 蛋白的缺乏，而是由于成牙本质细胞中异常 DSPP 的病理作用所致。这项提案“DSPP 功能、病理生理学和遗传诊断”旨在改善我们的不足 1）正常牙本质发生过程中DSPP衍生蛋白的分布，2）病理机制 Dspp -1 移码突变，以及 3) 开发 HDD 基因检测的实用方法，以专门识别可能的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初始形成和聚结过程中的作用通过表征 Dspp+/+、Dspp-1fs/-1fs、Dspp-2fs/-2fs 和 Dspp-/- 小鼠的早期牙本质矿化。 SA2：在体内定位 DSPP -1 移码蛋白，以确定其积累和引起的位置成牙本质细胞病理学。 SA3：通过建立高效的基因检测来改善 HDD 的诊断和管理算法（确定给定个体 HDD 确切遗传原因的操作序列）。策略：我们认为 DSPP 有助于启动牙本质钙质球蛋白的矿化，通过表征和比较，促进它们的生长和聚结成连续的矿物层。使用聚焦离子束扫描在 Dspp+/+、Dspp-/- 和 Dspp-2fs/-2fs 小鼠中进行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）还是牙本质磷蛋白 (DPP) 正在促进牙本质的起始和/或聚结我们捕获了 DSPP -1 移码。突变可能通过内质网应激引起成牙本质细胞病理学，我们使用该假设进行检验。通过评估与人类疾病极为相似的 Dspp -1 移码敲入小鼠。 FIB-SEM 和 TEM 双免疫金标记，用于体内突变蛋白和细胞器标记。改善HDD的诊断和管理，我们对招募的HDD应用基因检测算法家庭以优化其在识别潜在致病突变方面的可重复性和效率。

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

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

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