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）影响了8,000人中的1人。大多数HDD的遗传原因与牙本质蛋白的功能障碍：I型胶原蛋白和乙蛋白唾液磷蛋白（DSPP）。所有DSPP 迄今报告的突变显示出遗传的主要模式。这是因为DSPP突变通过功能机制的主要负面或增益来表现其表型，而不是单倍不足。与DSPP杂合小鼠一样，将正常数量的DSPP量减少一半，不会引起牙本质畸形。 DSPP - / - 无效小鼠由于缺乏DSPP而显示出严重的表型 - 不是常染色体显性病理机制，导致人类HDD。这种区别很重要。在治疗上，在没有DSPP的情况下，HDD可以通过恢复DSPP的表达来逆转，而由DSPP突变引起的人类硬盘无法以这种方式恢复由于缺乏DSPP蛋白，但由于异常细胞中异常DSPP的病理作用。该建议“ DSPP功能，病理生理学和遗传诊断”旨在改善我们的不足正常牙本质发生期间1）1）DSPP衍生的蛋白 DSPP -1移码突变，3）开发用于HDD基因检测的实用方法确定因果突变并建立确定的诊断。提出了三个具体目标： SA1：确定在初始牙本质矿物质形成和合并期间DSPP衍生蛋白的作用通过表征DSPP+/+，DSPP-1FS/-1FS，DSPP-2FS/-2FS和DSPP - / - 小鼠中的早期牙本质矿化。 SA2：在体内定位DSPP -1移状蛋白，以确定其积累和原因的位置 Odontoblast细胞病理学。 SA3：通过建立有效的基因检测来改善HDD的诊断和管理算法（识别给定个体中HDD确切遗传原因的动作序列）。策略：我们假设DSPP有助于启动牙本质钙磷酸盐的矿化和将它们的生长和合并成连续的矿物质层。通过表征和比较 DSPP+/+，DSPP - / - 和DSPP-2FS/-2FS小鼠的早期牙本质矿化，使用焦点离子束扫描电子显微镜（FIB-SEM），我们可以确定牙本质唾液蛋白（DSP）或牙本质磷蛋白是（DPP）正在促进牙本质的主动性和/或合并。我们假设DSPP -1 Frameshift 突变会导致ODONTOBAST细胞病理学，这可能是通过ER应激。我们使用 DSPP -1近距离敲击蛋白小鼠紧密模仿人类疾病。 Odontoblast病理由在体内用于突变蛋白和细胞器标记的Fib-SEM和TEM双免疫标记。到改善HDD的诊断和管理，我们将基因测试算法应用于招募HDD 家庭以优化其重现性和效率，以识别引起疾病的潜在突变。

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.