Mutations In RUNX2 Gene Research Articles

Identification of a Novel Splice Site Mutation in RUNX2 Gene in a Family with Rare Autosomal Dominant Cleidocranial Dysplasia.

Background:Pathogenic variants of RUNX2, a gene that encodes an osteoblast-specific transcription factor, have been shown as the cause of CCD, which is a rare hereditary skeletal and dental disorder with dominant mode of inheritance and a broad range of clinical variability. Due to the relative lack of clinical complications resulting in CCD, the medical diagnosis of this disorder is challenging, which leaves it underdiagnosed. Methods:In this study, nine healthy and affected members of an Iranian family were investigated. PCR and sequencing of all exons and exon-intron boundaries of RUNX2 (NM_001024630) gene was performed on proband. Co-segregation analysis was conducted in the other family members for the identified variant. Additionally, a cohort of 100 Iranian ethnicity-matched healthy controls was screened by ARMS-PCR method. Results:The novel splice site variant (c.860-2A>G), which was identified in the intron 6 of RUNX2 gene, co-segregated with the disease in the family, and it was absent in healthy controls. Pathogenicity of this variant was determined by several software, including HSF, which predicts the formation or disruption of splice donor sites, splice acceptor sites, exonic splicing silencer sites, and exonic splicing enhancer sites. In silico analysis predicted this novel variant to be disease causing. Conclusion:The identified variant is predicted to have an effect on splicing, which leads to exon skipping and producing a truncated protein via introducing a premature stop codon.

Retraction: Omid Daneshjoo, Pirooz Ebrahimi, Leila B. Salehi, Antonio Pizzuti, Masoud Garshasbi (2020). Identification of a novel RUNX2 gene mutation and early diagnosis of CCD in a cleidocranial dysplasia suspected Iranian family. Clin Case Rep. 2020; 1-8.

The above article from Clinical Case Reports, published online on 3 April 2020 in Wiley Online Library as Early View (https://onlinelibrary.wiley.com/doi/full/10.1002/ccr3.2825), has been retracted by agreement between Dr Masoud Garshasbi, the Editor‐in‐Chief and John Wiley and Sons Ltd. The retraction has been agreed because the article has been submitted and approved for publication by Dr. Omid Daneshjoo without consent in any form from the named co‐authors and Dr. Masoud Garshasbi. Reference Daneshjoo O, Ebrahimi P, Salehi LB, Pizzuti A, Garshasbi M. Identification of a novel RUNX2 gene mutation and early diagnosis of CCD in a cleidocranial dysplasia suspected Iranian family (2020). Clin Case Rep. 2020;1‐8.

An 18 bps in-frame deletion mutation in RUNX2 gene is a population polymorphism rather than a pathogenic variant

We recruited a family with an affected child exhibiting features of cleidocranial dysplasia with some phenotypic variations from reported cases. Whole exome sequencing data analysis identified an 18-bps heterozygous in-frame deletion variant (c.243-260delGGCGGCTGCGGCGGCGGC) in the RUNX2 gene. Sanger sequencing validated the presence of deletion in affected individual. Initially, we considered this variant as a causal mutation for the patient's phenotype based on previous report(s). However, further analysis of variant revealed that it is present in high frequency in variety of genome variation databases. Moreover, segregation analysis discovered the presence of variant in mother as well. Furthermore, screening of population matched control individuals revealed that the variant is present in apparently healthy individuals as well. Three-dimensional structures of the wild-type and mutant RUNX2 protein (p.Ala82_Ala87del) were analysed and it was found that both wild type and mutant protein show similar secondary structure pattern. Presence of RUNX2 deletion variant (c.243-260delGGCGGCTGCGGCGGCGGC) in control individuals, its high population frequency, benign effect on the overall protein structure lead to the argument that this variant is a population polymorphism and not a pathogenic mutation.

A novel gene mutation of Runx2 in cleidocranial dysplasia.

Haploinsufficiency of the runt-related transcription factor 2 (Runx2) gene is widely known to be responsible for cleidocranial dysplasia (CCD). To date, more than 190 mutations in Runx2 gene have been reported to be related to CCD. In this study, a novel mutation of Runx2 gene was observed in a female with CCD. Genomic DNA was extracted from peripheral venous blood of the proband and eleven members of her family. Genetic testing on these twelve people identified a novel missense mutation (c.895 T>C, Y299H) in exon 5 of the RUNX2 gene in the proband. This mutation results in an amino acid change at codon 895 (P.Tyr 299 His.) from a tryptophan codon (TAT) to a histidine codon (CAT). Our finding may further extend the known mutation spectrum of the RUNX2 gene, and facilitate prenatal genetic diagnosis of CCD in the future.

A novel RUNX2 mutation in exon 8, G462X, in a patient with Cleidocranial Dysplasia.

To identify a novel mutation of Runx2 gene in Cleidocranial Dysplasia (CCD) patients and to characterize the functional consequences of this mutation. The subjects consisted of 12 Korean CCD patients. After oral epithelial cells were collected using a mouthwash technique, genomic DNA was extracted. Screening for Runx2 mutation was performed using direct sequencing of polymerase chain reaction (PCR) products for exons 1-8. Restriction fragment length polymorphism (RFLP) analysis was performed to confirm the novel mutation. For functional studies, we performed luciferase assay for Runx2 transacting activity, cyclohexamide chase assay for Runx2 protein stability, real-time PCR for mRNA level of Runx2 downstream bone marker genes, and alkaline phosphatase (ALP) staining assay in mesenchymal stem cells for osteoblast differentiation. Of the 12 patients, seven showed Runx2 mutations reported previously and four showed no mutation. A novel mutation, G462X in exon 8, which was located in the C-terminus of proline/serine/threonine-rich (PST) domain, was found in one patient. In the luciferase assay, Runx2 transacting activity was decreased in Runx2-G462X transfected cells. In the cyclohexamide chase assay, Runx2-G462X mutation reduced the stability of Runx2 protein. Expression of the bone marker genes (osteocalcin, ALP, Type I collagen αI, matrix metalloproteinase-13, bone sialoprotein, and osteopontin) decreased in G462X-transfected cells. In the ALP staining assay, osteoblast differentiation was reduced in Runx2-G462X overexpressed cell. The G462X mutation might reduce the Runx2 transacting activity, lower the protein stability, downgrade the expression of bone marker genes, and eventually diminish osteoblast differentiation in CCD patients.

Analysis of novel RUNX2 mutations in Chinese patients with cleidocranial dysplasia.

Cleidocranial dysplasia (CCD) is an autosomal dominant inheritable skeletal disorder characterized by cranial dysplasia, clavicle hypoplasia and dental abnormalities. This disease is mainly caused by heterozygous mutations in RUNX2, a gene that encodes an osteoblast-specific transcription factor. In the present study, mutational analyses of RUNX2 gene were performed on four unrelated Chinese patients with CCD. Four different RUNX2 mutations were detected in these patients, including one nonsense mutation (c.199C>T p.Q67X) and three missense mutations (c.338T>G p.L113R, c.557G>C p.R186T and c.673C>T p.R225W). Among them, two mutations (c.199C>T p.Q67X and c.557G>C p.R186T) were novel and the other two had been reported in previous literatures. Except for Q67X mutation located in the Q/A domain, other three mutations were clustered within the highly conserved Runt domain. Green fluorescent protein (GFP) and RUNX2 fusion protein analyses in vitro showed that nuclear accumulation of RUNX2 protein was disturbed by Q67X mutation, while the other two mutations (c.338T>G p.L113R and c.557G>C p.R186T) had no effects on the subcellular distribution of RUNX2. Luciferase reporter assay demonstrated that all the three novel RUNX2 mutations significantly reduced the transactivation activity of RUNX2 on osteocalcin promoter. Our findings enrich the evidence of molecular genetics that the mutations of RUNX2 gene are responsible for CCD.

A novel, complex RUNX2 gene mutation causes cleidocranial dysplasia

BackgroundHaploinsufficiency of the runt-related transcription factor 2 (RUNX2) gene is known to cause cleidocranial dysplasia (CCD). Here, we investigated a complex, heterozygous RUNX2 gene mutation in a Chinese family with CCD and the pathogenesis associated with the variations.MethodsGenomic DNA extracted from peripheral venous blood was taken from the proband, her parents and 3 siblings, and 150 normal controls. Analysis of their respective RUNX2 gene sequences was performed by PCR amplification and Sanger sequencing. Pathogenesis associated with RUNX2 mutations was investigated by performing bioinformatics, real-time PCR, western blot analysis, and subcellular localization studies.ResultsWe identified 2 complex heterozygous mutations involving a c.398–399 insACAGCAGCAGCAGCA insertion and a c.411–412 insG frameshift mutation in exon 3 of the RUNX2 gene. The frameshift mutation changed the structure of the RUNX2 protein while did not affect its expression at the mRNA level. Transfection of HEK293T cells with a plasmid expressing the RUNX2 variant decreased the molecular weight of the variant RUNX2 protein, compared with that of the wild-type protein. Subcellular localization assays showed both nuclear and cytoplasmic localization for the mutant protein, while the wild-type protein localized to the nucleus.ConclusionsOur findings demonstrated that the novel c.398–399insACAGCAGCAGCAGCA mutation occurred alongside the c.411–412insG frameshift mutation, which resulted in RUNX2 truncation. RUNX2 haploinsufficiency was associated with CCD pathogenesis. These results extend the known mutational spectrum of the RUNX2 gene and suggest a functional role of the novel mutation in CCD pathogenesis.

Two novel mutations of RUNX2 gene in two sporadic cleidocranial dysplasia patients

Two novel mutations of RUNX2 gene in two sporadic cleidocranial dysplasia patients

Skp2 inhibits osteogenesis by promoting ubiquitin–proteasome degradation of Runx2

Osteogenic transcription factor Runx2 is essential for osteoblast differentiation. The activity of Runx2 is tightly regulated at transcriptional as well as post-translational level. However, regulation of Runx2 stability by ubiquitin mediated proteasomal degradation by E3 ubiquitin ligases is little-known. Here, for the first time we demonstrate that Skp2, an SCF family E3 ubiquitin ligase negatively targets Runx2 by promoting its polyubiquitination and proteasome dependent degradation. Co-immunoprecipitation studies revealed that Skp2 physically interacts with Runx2 both in a heterologous as well as physiologically relevant system. Functional consequences of Runx2–Skp2 physical interaction were then assessed by promoter reporter assay. We show that Skp2-mediated downregulation of Runx2 led to reduced Runx2 transactivation and osteoblast differentiation. On the contrary, inhibition of Skp2 restored Runx2 levels and promoted osteoblast differentiation. We further show that Skp2 and Runx2 proteins are co-expressed and show inverse relation in vivo such as in lactating, ovariectomized and estrogen-treated ovariectomized animals. Together, these data demonstrate that Skp2 targets Runx2 for ubiquitin mediated degradation and hence negatively regulate osteogenesis. Therefore, the present study provides a plausible therapeutic target for osteoporosis or cleidocranial dysplasia caused by the heterozygous mutation of Runx2 gene.

Effect and Possible Mechanism of Network Between MicroRNAs and RUNX2 Gene on Human Dental Follicle Cells

To investigate whether crosstalk between RUNX2 and miRNAs is involved in tooth eruption regulated by dental follicle cells (DFCs) and the possible molecular mechanism. Blood samples and embedded dental follicles were collected from patients with cleidocranial dysplasia, and RUNX2 gene mutations were analyzed, then RUNX2(+/m) DFCs were isolated and identified. The characteristics of RUNX2(+/m) DFCs were analyzed. The differential expression of miRNAs was detected between the RUNX2(+/m) DFCs and RUNX2(+/+) DFCs by microarray, and target genes were predicted by miRGen. miR-146a was chosen for further investigation, and its effects in DFCs were analyzed by transfecting its mimics and inhibitors, and expression of genes involved in tooth eruption were detected. A novel insertion mutation (c.309_310insTG) of RUNX2 gene was identified which had an effect on the characteristics of DFCs. Compared with the RUNX2(+/+) DFCs, there were 69 microRNAs more than twofold up-regulated and 54 microRNAs more than twofold down-regulated in the RUNX2(+/m) DFCs. Among these, miR-146a decreased significantly in RUNX2(+/m) DFCs, and expression of RUNX2, CSF-1, EGFR, and OPG was significantly altered when miR-146a was overexpressed or inhibited. RUNX2 gene mutation contributes to the characteristic change of DFCs, and the crosstalk between RUNX2 gene and miRNAs may be one of the key regulatory mechanisms of differentiation of DFCs.

Cleidocranial dysplasia: oral features and genetic analysis of 11 patients

Cleidocranial dysplasia (CCD) is a dominantly inherited autosomal disease characterized by typical bone defects including short stature, persistently open or delayed closure of the cranial sutures, and hypoplastic or aplastic clavicles. Oral features are frequent and include supernumerary teeth, delayed eruption or impaction of the permanent teeth, and malocclusion. Heterozygous mutations in RUNX2 gene, which encodes a transcription factor essential for osteoblast differentiation, were identified as the etiological cause of CCD. Herein, we performed physical and radiographic examination and screening for RUNX2 mutations in 11 patients from five families with CCD. All patients demonstrated the classical phenotypes related to CCD. Families whose affected members had several dental alterations such as multiple impacted and supernumerary teeth demonstrated heterozygous missense mutations (R190Q and R225Q) that impair the runt domain of RUNX2. On the other hand, CCD patients from families with low frequency of dental abnormalities showed no mutation in RUNX2 or mutation outside of the runt domain (Q292fs→X299). The current findings suggest a correlation between dental alterations and mutations in the runt domain of RUNX2 in CCD patients. Further clinical and genetic studies are needed to clarify the relationship between phenotypes and genotypes in CCD and to identify other factors that might influence the clinical features of this uncommon disease.

Identification of a novel RUNX2 gene mutation in an Italian family with cleidocranial dysplasia

Cleidocranial dysplasia (CCD) is a rare, well-defined skeletal disorder with autosomal dominant inheritance and complete penetrance. Although it involves the whole skeletal system, the main clinical manifestations of CCD are malformations of the skull and clavicles, which lead to a typical appearance of the face and shoulders. Dental aspects are particularly evident and often eruption difficulties are the first indication for the patient, who does not present any other problem. It has been established that insufficiency of the RUNX-related transcription factor, the core-binding factor alpha 1 (CBFA1) protein, causes CCD. This protein is essential in skeletal development by regulating osteoblast differentiation and chondrocyte maturation. CBFA1 protein is encoded by the RUNX2 gene located on chromosome 6p21. The molecular characterization of the novel RUNX2 gene mutation c.580 + 1G > A in an Italian family (a 27-year-old female, her 54-year-old mother and 24-year-old sister) affected by the typical CCD phenotype, which was proven to alter splicing of the RUNX2 messenger RNA, underscoring the contribution of novel altered splicing mechanism to the aetiology of this disease is presented.

Correlation between genotype and supernumerary tooth formation in cleidocranial dysplasia

Cleidocranial dysplasia (CCD, MIM#119600), for which the responsible gene is RUNX2, is a genetic disorder characterized by hypoplasia or aplasia of the clavicles, patent fontanelles, and a short stature. Supernumerary teeth and delayed eruption and impaction of permanent teeth are frequently associated with CCD. Our previous study reported wide intrafamilial variation in supernumerary tooth formation associated with a mutation in the RUNT-domain of RUNX2, suggesting a low correlation between the genotype and supernumerary tooth formation. To further clarify this point, a more precise evaluation was performed. Gene mutational analysis of nine Japanese individuals with CCD was performed. Dental and skeletal characteristics were examined based on patient examinations and radiographs. Four different gene mutations, including one novel mutation in RUNX2 gene (NM_001024630), were identified. Among them, four individuals had the R225Q mutation, three siblings had the P224S mutation, and the other two individuals had different frame-shift mutations. Wide variations in supernumerary tooth formation were observed in individuals with identical gene mutations, and discordance was seen between monozygotic twins. Asymmetric supernumerary tooth formation was noted in five out of the nine individuals. Individuals with identical gene mutations showed a wide variation in the supernumerary tooth formation. Not only the genotype but also environmental factors and a complex system including epigenetics and copy number variation might regulate supernumerary tooth formation in CCD.

Two novel RUNX2 gene mutations in two Chinese families with cleidocranial dysplasia

To identify the RUNX2 gene mutation in two unrelated Chinese families with cleidocranial dysplasia (CCD), and to assess the feasibility of gene diagnosis for patients with CCD. Genomic DNA was isolated from peripheral blood samples of 4 patients and 4 healthy members in the two pedigrees as well as 102 unrelated healthy controls. All 7 coding exons and their flanking intronic sequences of the RUNX2 gene were amplified by PCR, then the PCR products were sequenced bi-directionally. The sequencing results were compared with normal sequences in GenBank to identify the mutation. The mutation was confirmed by RFLP with restriction endonuclease. In one family, a novel heterozygous missense mutation c.346T to A (W116R) in exon 1 of the RUNX2 gene was detected in the two affected individuals, and the mutation was further confirmed with Bsr I restriction endonuclease digestion. In the other family, a novel nonsense mutation c.610A TO T (K204X) was identified in the two patients. No above sequence change was found in the 102 healthy controls. Two novel RUNX2 mutations were found in two unrelated Chinese families with cleidocranial dysplasia. The identification of these mutations further extended the mutation spectrum of RUNX2 gene and will facilitate prenatal diagnosis and gene diagnosis of CCD.

Dysregulation of Chondrogenesis in Human Cleidocranial Dysplasia

Cleidocranial dysplasia (CCD) is an autosomal dominant skeletal dysplasia caused by heterozygosity of mutations in human RUNX2. The disorder is characterized by delayed closure of the fontanel and hypoplastic clavicles that result from defective intramembranous ossification. However, additional features, such as short stature and cone epiphyses, also suggest an underlying defect in endochondral ossification. Here, we report observations of growth-plate abnormalities in a patient with a novel RUNX2 gene mutation, a single C insertion (1228insC), which is predicted to lead to a premature termination codon and thus to haploinsufficiency of RUNX2 and the CCD phenotype. Histological analysis of the rib and long-bone cartilages showed a markedly diminished zone of hypertrophy. Quantitative real-time reverse transcription-polymerase chain reaction analysis of limb cartilage RNA showed a 5-10-fold decrease in the hypertrophic chondrocyte molecular markers VEGF, MMP13, and COL10A1. Together, these data show that humans with CCD have altered endochondral ossification due to altered RUNX2 regulation of hypertrophic chondrocyte-specific genes during chondrocyte maturation.