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Dentin defects caused by a Dspp frameshift mutation are associated with the activation of autophagy.Scientific Reports Apr 2023Dentin sialophosphoprotein (DSPP) is primarily expressed by differentiated odontoblasts (dentin-forming cells), and transiently expressed by presecretory ameloblasts...
Dentin sialophosphoprotein (DSPP) is primarily expressed by differentiated odontoblasts (dentin-forming cells), and transiently expressed by presecretory ameloblasts (enamel-forming cells). Disease-causing DSPP mutations predominantly fall into two categories: 5' mutations affecting targeting and trafficking, and 3' - 1 frameshift mutations converting the repetitive, hydrophilic, acidic C-terminal domain into a hydrophobic one. We characterized the dental phenotypes and investigated the pathological mechanisms of Dspp and Dspp mice that replicate the two categories of human DSPP mutations. In Dspp mice, dentin is less mineralized but contains dentinal tubules. Enamel mineral density is reduced. Intracellular accumulation and ER retention of DSPP is observed in odontoblasts and ameloblasts. In Dspp mice, a thin layer of reparative dentin lacking dentinal tubules is deposited. Odontoblasts show severe pathosis, including intracellular accumulation and ER retention of DSPP, strong ubiquitin and autophagy activity, ER-phagy, and sporadic apoptosis. Ultrastructurally, odontoblasts show extensive autophagic vacuoles, some of which contain fragmented ER. Enamel formation is comparable to wild type. These findings distinguish molecular mechanisms underlying the dental phenotypes of Dspp and Dspp mice and support the recently revised Shields classification of dentinogenesis imperfecta caused by DSPP mutations in humans. The Dspp mice may be valuable for the study of autophagy and ER-phagy.
Topics: Mice; Humans; Animals; Frameshift Mutation; Extracellular Matrix Proteins; Odontoblasts; Mutation; Phosphoproteins; Sialoglycoproteins; Dentin; Autophagy
PubMed: 37076504
DOI: 10.1038/s41598-023-33362-1 -
Clinical Oral Investigations Jul 2023To investigate the genetic causes and teeth characteristics of dentin dysplasia Shields type II(DD-II) in three Chinese families.
OBJECTIVES
To investigate the genetic causes and teeth characteristics of dentin dysplasia Shields type II(DD-II) in three Chinese families.
MATERIALS AND METHODS
Data from three Chinese families affected with DD-II were collected. Whole-exome sequencing (WES) and whole-genome sequencing (WGS) were conducted to screen for variations, and Sanger sequencing was used to verify mutation sites. The physical and chemical characteristics of the affected teeth including tooth structure, hardness, mineral content, and ultrastructure were investigated.
RESULTS
A novel frameshift deletion mutation c.1871_1874del(p.Ser624fs) in DSPP was found in families A and B, while no pathogenic mutation was found in family C. The affected teeth's pulp cavities were obliterated, and the root canals were smaller than normal teeth and irregularly distributed comprising a network. The patients' teeth also had reduced dentin hardness and highly irregular dentinal tubules. The Mg content of the teeth was significantly lower than that of the controls, but the Na content was obviously higher than that of the controls.
CONCLUSIONS
A novel frameshift deletion mutation, c.1871_1874del (p.Ser624fs), in the DPP region of the DSPP gene causes DD-II. The DD-II teeth demonstrated compromised mechanical properties and changed ultrastructure, suggesting an impaired function of DPP. Our findings expand the mutational spectrum of the DSPP gene and strengthen the understanding of clinical phenotypes related to the frameshift deletion in the DPP region of the DSPP gene.
CLINICAL RELEVANCE
A DSPP mutation can alter the characteristics of the affected teeth, including tooth structure, hardness, mineral content, and ultrastructure.
Topics: Humans; Dentin; Dentinogenesis; Dentinogenesis Imperfecta; Extracellular Matrix Proteins; Mutation; Phenotype; Tooth
PubMed: 37017752
DOI: 10.1007/s00784-023-05009-y -
Human Gene Therapy Jun 2023Dentin is a major type of hard tissue of teeth and plays essential roles for normal tooth function. Odontoblasts are responsible for dentin formation. Mutations or...
Dentin is a major type of hard tissue of teeth and plays essential roles for normal tooth function. Odontoblasts are responsible for dentin formation. Mutations or deficiency in various genes affect the differentiation of odontoblasts, leading to irreversible dentin developmental defects in animals and humans. Whether such dentin defects can be reversed by gene therapy for odontoblasts remains unknown. In this study, we compare the infection efficiencies of six commonly used adeno-associated virus (AAV) serotypes (AAV1, AAV5, AAV6, AAV8, AAV9, and AAVDJ) in cultured mouse odontoblast-like cells (OLCs). We show that AAV6 serotype infects OLCs with the highest efficiency among the six AAVs. Two cellular receptors, which are able to recognize AAV6, AAV receptor (AAVR), and epidermal growth factor receptor (EGFR), are strongly expressed in the odontoblast layer of mouse teeth. After local administration to mouse molars, AAV6 infects the odontoblast layer with high efficiency. Furthermore, AAV6-Mdm2 was successfully delivered to teeth and prevents the defects in odontoblast differentiation and dentin formation in conditional knockout mice (a mouse model of dentinogenesis imperfecta type Ⅲ). These results suggest that AAV6 can serve as a reliable and efficient vehicle for gene delivery to odontoblasts through local injection. In addition, human OLCs were also successfully infected by AAV6 with high efficiency, and both AAVR and EGFR are strongly expressed in the odontoblast layer of extracted human developing teeth. These findings suggest that AAV6-mediated gene therapy through local injection may be a promising treatment approach for hereditary dentin disorders in humans.
Topics: Mice; Humans; Animals; Dentin; Dentinogenesis Imperfecta; Extracellular Matrix Proteins; Phosphoproteins; Sialoglycoproteins; Mice, Knockout; Cell Differentiation; ErbB Receptors; Genetic Therapy
PubMed: 37014084
DOI: 10.1089/hum.2023.008 -
Zhonghua Kou Qiang Yi Xue Za Zhi =... Apr 2023Heterogeneous mutations in dentin sialophosphoprotein (DSPP) gene, which is located on autosome 4, are associated with hereditary dentin developmental disorders....
Heterogeneous mutations in dentin sialophosphoprotein (DSPP) gene, which is located on autosome 4, are associated with hereditary dentin developmental disorders. According to the new classification proposed by de La Dure-Molla et al, diseases caused by DSPP gene mutations mainly manifested as abnormal dentin development are collectively referred to as dentinogenesis imperfecta (DI), including dentin dysplasia type Ⅱ (DD-Ⅱ), dentinogenesis imperfecta type Ⅱ (DGI-Ⅱ) and dentinogenesis imperfecta type Ⅲ (DGI-Ⅲ) in Shields classification. And dentin dysplasia type Ⅰ (DD-Ⅰ) in Shields classification is redesignated as radicular dentin dysplasia. In this paper, progress in the classification, clinical characteristics and genetic mechanisms of DI are reviewed. This paper also provides clinical management and treatment strategies for patients suffering DI.
PubMed: 37005776
DOI: 10.3760/cma.j.cn112144-20230210-00041 -
Journal of Dental Research Jun 2023Dentinogenesis imperfecta (DI) is the main orodental manifestation of osteogenesis imperfecta (OI) caused by or heterozygous pathogenic variants. Its prevalence varies...
Dentinogenesis imperfecta (DI) is the main orodental manifestation of osteogenesis imperfecta (OI) caused by or heterozygous pathogenic variants. Its prevalence varies according to the studied population. Here, we report the molecular analysis of 81 patients with OI followed at reference centers in Brazil and France presenting or variants. Patients were submitted to clinical and radiographic dental examinations to diagnose the presence of DI. In addition, a systematic literature search and a descriptive statistical analysis were performed to investigate OI/DI phenotype-genotype correlation in a worldwide sample. In our cohort, 50 patients had pathogenic variants, and 31 patients had variants. A total of 25 novel variants were identified. Overall, data from a total of 906 individuals with OI were assessed. Results show that DI was more frequent in severe and moderate OI cases. DI prevalence was also more often associated with (67.6%) than with variants (45.4%) because variants mainly lead to qualitative defects that predispose to DI more than quantitative defects. For the first time, 4 DI hotspots were identified. In addition, we showed that 1) glycine substitution by branched and charged amino acids in the α2(I) chain and 2) substitutions occurring in major ligand binding regions-MLRB2 in α1(I) and MLBR 3 in α2(I)-could significantly predict DI ( < 0.05). The accumulated variant data analysis in this study provides a further basis for increasing our comprehension to better predict the occurrence and severity of DI and appropriate OI patient management.
Topics: Humans; Collagen Type I; Collagen Type I, alpha 1 Chain; Dentinogenesis Imperfecta; Genetic Association Studies; Mutation; Osteogenesis Imperfecta
PubMed: 36951356
DOI: 10.1177/00220345231154569 -
Orphanet Journal of Rare Diseases Feb 2023Osteogenesis imperfecta (OI) is a rare, connective tissue disorder characterised by bone fragility, resulting in recurrent fractures and skeletal deformities....
BACKGROUND
Osteogenesis imperfecta (OI) is a rare, connective tissue disorder characterised by bone fragility, resulting in recurrent fractures and skeletal deformities. Extra-skeletal manifestations include dentinogenesis imperfecta, hearing abnormalities and lung disease. These co-morbidities combined with recurrent fractures can exert a significant impact on health-related quality of life (HR-QOL). It is important to assess HR-QOL throughout adulthood because the prevalence of some OI-specific complications increases with age.
METHODS
PubMed, EMBASE and CENTRAL databases were searched on 2nd February 2022 to identify studies reporting quantitative assessments of HR-QOL in adults with OI. The primary endpoint was to determine the impact of an OI diagnosis on adult's HR-QOL. Secondary endpoints were to (i) examine how frequently various HR-QOL assessment tools were used (ii) identify differences in HR-QOL between OI types and (iii) investigate the determinants of HR-QOL in adults with OI. Search results were exported to Endnote where two reviewers independently conducted title/abstract and full-text reviews. Data from accepted studies were extracted into Microsoft Excel. A narrative synthesis was then undertaken.
RESULTS
The review identified 17 studies with a total of 1,648 adults. The Short Form-36 (SF-36) was the most frequently reported HR-QOL assessment tool and was used in nine studies. Physical HR-QOL was reduced in adults with OI. Physical component scores (PCS) or individual physical domains of the SF-36 were lower in eight of nine studies. Mental component scores (MCS) were preserved in all six studies, however individual mental health domains of the SF-36 were reduced in some studies. The prevalence of anxiety/depression was relatively low in adults with OI. Those with type III OI had lower physical and respiratory HR-QOL but preserved mental HR-QOL compared with type I. The prevalence of fatigue and pain was higher in adults with OI compared with reference populations. Age and cardio-pulmonary co-morbidities were associated with lower HR-QOL.
CONCLUSION
OI in adulthood has a wide-ranging negative impact on HR-QOL. Physical and respiratory HR-QOL were lower, while the prevalence of pain and fatigue were higher than in reference populations. Mental HR-QOL was relatively preserved, although some deficits were identified. Age and cardio-pulmonary co-morbidities were associated with lower HR-QOL.
Topics: Adult; Humans; Osteogenesis Imperfecta; Quality of Life; Pain; Fatigue; Prevalence
PubMed: 36814291
DOI: 10.1186/s13023-023-02643-3 -
European Journal of Medical Genetics Apr 2023Genetic skeletal disorders are clinically and genetically heterogeneous group of disorders that affect the normal development, growth, and maintenance of the human...
Spondylo-meta-epiphyseal dysplasia (SMED), short limb-hand abnormal calcification type: Further expanding the mutational spectrum and dental findings of three new patients.
Genetic skeletal disorders are clinically and genetically heterogeneous group of disorders that affect the normal development, growth, and maintenance of the human skeleton. Spondylo-meta-epiphyseal dysplasia, short limb-abnormal calcification type (SMED-SL/AC; MIM# 271665) is a rare autosomal recessive genetic skeletal disorder characterized by distinctive facial features, disproportionate short stature, vertebral, metaphyseal, and epiphyseal abnormalities. This unique phenotype is caused by biallelic loss-of-function variants in Discoidin domain receptor 2 gene (DDR2, MIM# 191311). To date, only 10 pathogenic variants (six missense, two nonsense, one deletion, and one splice site) in DDR2 have been reported in patients with SMED-SL/AC. Dental anomalies related to skeletal dysplasia can include various abnormalities in the number, shape, and position of teeth in the jaw, as well as enamel hypoplasia and dentinogenesis imperfecta. Although abnormal dentition has previously been reported, orodental findings were described in only six patients with SMED-SL/AC. This study aimed to define the clinical, dental, radiological, and molecular findings of three new SMED-SL/AC patients from three unrelated families. Three DDR2 variants, two of which were novel, were detected with the aid of Sanger sequencing. Interestingly, one of the patients was diagnosed with Wilson's disease (WD) during the follow-up, a co-occurrence that has never been reported in patients with SMED-SL/AC so far.
Topics: Humans; Mutation; Osteochondrodysplasias; Dwarfism; Calcinosis
PubMed: 36720430
DOI: 10.1016/j.ejmg.2023.104708 -
Zhonghua Kou Qiang Yi Xue Za Zhi =... Jan 2023The classification as well as the clinical manifestations of hereditary malformations of dentin are of great concern and have been deeply elucidated. The understanding...
The classification as well as the clinical manifestations of hereditary malformations of dentin are of great concern and have been deeply elucidated. The understanding of its genetic basis also increases progressively. Dentin sialophosphoprotein (DSPP) is the pathogenic gene of dentinogenesis imperfecta type Ⅱ, dentinogenesis imperfecta type Ⅲ and dentin dysplasia type Ⅱ. In this article, the classification of DSPP mutations as well as the resultant dysfunction of the mutant DSPP are summarized respectively and the corresponding clinical manifestations are analyzed. This work will provide a reference for the diagnosis and treatment of hereditary malformations of dentin.
Topics: Humans; Dentinogenesis Imperfecta; Mutation; Extracellular Matrix Proteins; Phosphoproteins; Sialoglycoproteins; Dentin
PubMed: 36642448
DOI: 10.3760/cma.j.cn112144-20221009-00521 -
Oral Diseases Sep 2023The present study aims to investigate the mutation in a Chinese family with dentin dysplasia type II (DD-II) and to summarize mutation hotspots, clinical manifestations,... (Review)
Review
The present study aims to investigate the mutation in a Chinese family with dentin dysplasia type II (DD-II) and to summarize mutation hotspots, clinical manifestations, and disease management strategies. Phenotype analysis, clinical intervention, mutation screening, and cosegregation analysis within the enrolled family were performed. A summary of the reported mutations in the dentin phosphoprotein (DPP) region of dentin sialophosphoprotein (DSPP) was analyzed. Pathogenicity prediction analysis of the physical properties and function of DSPP variants was performed by bioinformatic processing. Clinical management strategies are discussed. A novel pathogenic mutation (c.2035delA) in the DPP region of DSPP was identified, which was cosegregated in the family. The immature permanent teeth of patients with DD-II presented with X-shaped root canal phenotypes. Most of the identified mutations for DD-II were clustered in the DPP region between nucleotides 1686-2134. Points of differential diagnosis, clinical interventions, and management strategies are proposed. This study revealed a novel DSPP frameshift mutation and presented new clinical features of DD-II. The locus involving nucleotides 1686-2134 of DSPP may represent a mutational hotspot for the disease. Appropriate management of DD-II at different stages is important to avoid the development of secondary dental lesions.
Topics: Humans; Dentin; Dentin Dysplasia; Dentinogenesis Imperfecta; Disease Management; Extracellular Matrix Proteins; Frameshift Mutation; Hyperplasia; Mutation; Nucleotides; Phosphoproteins; Sialoglycoproteins
PubMed: 36597617
DOI: 10.1111/odi.14494