METTL3-dependent m6A modification of PSEN1 mRNA regulates craniofacial development through the Wnt/ß-catenin signaling pathway.

Craniofacial malformations, often associated with syndromes, are prevalent birth defects. Emerging evidence underscores the importance of m6A modifications in various bioprocesses such as stem cell differentiation, tissue development, and tumorigenesis. Here, in vivo, experiments with zebrafish models revealed that mettl3-knockdown embryos at 144 h postfertilization exhibited aberrant craniofacial features, including altered mouth opening, jaw dimensions, ethmoid plate, tooth formation and hypoactive behavior. Similarly, low METTL3 expression inhibited the proliferation and migration of BMSCs, HEPM cells, and DPSCs. Loss of METTL3 led to reduced mRNA m6A methylation and PSEN1 expression, impacting craniofacial phenotypes. Co-injection of mettl3 or psen1 mRNA rescued the level of Sox10 fusion protein, promoted voluntary movement, and mitigated abnormal craniofacial phenotypes induced by mettl3 knockdown in zebrafish. Mechanistically, YTHDF1 enhanced the mRNA stability of m6A-modified PSEN1, while decreased METTL3-mediated m6A methylation hindered ß-catenin binding to PSEN1, suppressing Wnt/ß-catenin signaling. Pharmacological activation of the Wnt/ß-catenin pathway partially alleviated the phenotypes of mettl3 morphant and reversed the decreases in cell proliferation and migration induced by METTL3 silencing. This study elucidates the pivotal role of METTL3 in craniofacial development via the METTL3/YTHDF1/PSEN1/ß-catenin signaling axis.

Exploring the roles of noncoding RNAs in craniofacial abnormalities: A systematic review.

Congenital craniofacial abnormalities are congenital anomalies of variable expressivity and severity with a recognizable set of abnormalities, which are derived from five identifiable primordial structures. They can occur unilaterally or bilaterally and include various malformations such as cleft lip with/without palate, craniosynostosis, and craniofacial microsomia. To date, the molecular etiology of craniofacial abnormalities is largely unknown. Noncoding RNAs (ncRNAs), including microRNAs, long ncRNAs, circular RNAs and PIWI-interacting RNAs, function as major regulators of cellular epigenetic hallmarks via regulation of various molecular and cellular processes. Recently, aberrant expression of ncRNAs has been implicated in many diseases, including craniofacial abnormalities. Consequently, this review focuses on the role and mechanism of ncRNAs in regulating craniofacial development in the hope of providing clues to identify potential therapeutic targets.

FGFR1 variants contributed to families with tooth agenesis.

BACKGROUND: Tooth agenesis is a common dental anomaly that can substantially affect both the ability to chew and the esthetic appearance of patients. This study aims to identify possible genetic factors that underlie various forms of tooth agenesis and to investigate the possible molecular mechanisms through which human dental pulp stem cells may play a role in this condition. RESULTS: Using whole-exome sequencing of a Han Chinese family with non-syndromic tooth agenesis, a rare mutation in FGFR1 (NM_001174063.2: c.103G > A, p.Gly35Arg) was identified as causative and confirmed by Sanger sequencing. Via GeneMatcher, another family with a known variant (NM_001174063.2: c.1859G > A, p.Arg620Gln) was identified and diagnosed with tooth agenesis and a rare genetic disorder with considerable intrafamilial variability. Fgfr1 is enriched in the ectoderm during early embryonic development of mice and showed sustained low expression during normal embryonic development of Xenopus laevis frogs. Functional studies of the highly conserved missense variant c.103G > A showed deleterious effects. FGFR1 (c.103G > A) was overexpressed compared to wildtype and promoted proliferation while inhibiting apoptosis in HEK293 and human dental pulp stem cells. Moreover, the c.103G > A variant was found to suppress the epithelial-mesenchymal transition. The variant could downregulate ID4 expression and deactivate the TGF-beta signaling pathway by promoting the expression of SMAD6 and SMAD7. CONCLUSION: Our research broadens the mutation spectrum associated with tooth agenesis and enhances understanding of the underlying disease mechanisms of this condition.

A TP63 mutation identified in a Han Chinese family with ectodermal dysplasia.

OBJECTIVE: The purpose of this study was to identify a pathogenic mutation located in TP63 in a nuclear Han Chinese family. DESIGN: Whole-exome sequencing and Sanger sequencing were performed to identify candidate variants. The AlphaFold and PyMOL predicted the three-dimensional structure of the protein. Single-cell RNA-sequencing data and spatiotemporal transcriptomic atlas were used to generate the dissection of candidate gene expression at single-cell resolution. Significant genes (Pearson's coefficient ≥0.8 and P < 0.05) were identified for Gene Ontology (GO) analysis and Kyoto encyclopedia of genes and genomes (KEGG) pathways analysis. RESULTS: A heterozygous missense variant at TP63 exon 8 (c.1010 G>A:p.Arg337Gln) was identified in the proband. This variant was predicted deleterious and likely to impair the local stability of the protein. In addition, single-cell RNA-sequencing indicated that TP63 was highly expressed in skin tissues. Furthermore, spatial transcriptome data of mice embryos showed TP63 was mainly enriched in the mucosal epithelium, thymus, epidermis, mesenchyme, and surface ectoderm. GO and KEGG pathway annotation analysis revealed that TP63 played a positive role in the process of ectoderm via the TGF-beta signaling pathway. CONCLUSIONS: The missense variant of TP63 (c.1010 G>A:p.Arg337Gln) was associated with ectodermal dysplasia.

Robust and Precise Quantitative Real-Time Polymerase Chain Reaction with an Amplification Efficiency-Aware Reaction Kinetics Model.

Quantitative real-time PCR (qPCR) is a method extensively used in nucleic acid testing for plants and animals. During the coronavirus disease 2019 (COVID-19) pandemic, high-precision qPCR analysis was urgently needed since quantitative results obtained from conventional qPCR methods were not accurate and precise, causing misdiagnoses and high rates of false-negative. To achieve more accurate results, we propose a new qPCR data analysis method with an amplification efficiency-aware reaction kinetics model (AERKM). Our reaction kinetics model (RKM) mathematically describes the tendency of the amplification efficiency during the whole qPCR process inferred by biochemical reaction dynamics. Amplification efficiency (AE) was introduced to rectify the fitted data so as to match the real reaction process for individual tests, thus reducing errors. The 5-point 10-fold gradient qPCR tests of 63 genes have been verified. The results of a 0.9% slope bias and an 8.2% ratio bias using AERKM exceed 4.1 and 39.4%, respectively, of the best performance of existing models, which demonstrates higher precision, less fluctuation, and better robustness among different nucleic acids. AERKM also provides a better understanding of the real qPCR process and gives insights into the detection, treatment, and prevention of severe diseases.

A Genome-wide association study of premolar agenesis in a chinese population.

OBJECTIVE: Premolar agenesis is a common subtype of tooth agenesis. Although a genome-wide study (GWAS) has identified some variants involved in tooth agenesis in Europeans, the genetic mutation related to premolar agenesis in the Chinese population remains unclear. MATERIALS AND METHODS: We present a GWAS in 218 premolar agenesis cases and 1,222 controls using the Illumina Infinium® Global Screening Array. 5,585,618 single nucleotide polymorphisms (SNPs) were used for tests of associations with premolar agenesis. RESULTS: Four independent SNPs on chromosome 2 were identified as susceptibility loci, including rs147680216, rs79743039, rs60540881, and rs6738629. The genome-wide significant SNP rs147680216 (p = 6.09 × 10-9 ) was predicted to change the structure of the WNT10A protein and interact with hedgehog signaling pathway components. Meta-analysis showed that the rs147680216 A allele significantly increased the risk of tooth agenesis (p = 0.000). The other three SNPs with nominal significance are novel susceptibility loci. Of them, rs6738629 (p = 5.40 × 10-6 ) acts as a potential transcriptional regulator of GCC2, a gene playing a putative role in dental and craniofacial development. CONCLUSION: Our GWAS indicates that rs147680216 and additional three novel susceptibility loci on chromosome 2 are associated with the risk of premolar agenesis in the Chinese population.

Genetic architecture of non-syndromic skeletal class III malocclusion.

Non-syndromic skeletal Class III malocclusion is a major craniofacial disorder characterized by genetic and environmental factors. Patients with severe skeletal Class III malocclusion require orthognathic surgery to obtain aesthetic facial appearance and functional occlusion. Recent studies have demonstrated that susceptible chromosomal regions and genetic variants of candidate genes play important roles in the etiology of skeletal Class III malocclusion. Here, we provide a comprehensive review of our current understanding of the genetic factors that affect non-syndromic skeletal Class III malocclusion, including the patterns of inheritance and multiple genetic approaches. We then summarize the functional studies on related loci and genes using cell biology and animal models, which will help to implement individualized therapeutic interventions.

Skeletal Class III Malocclusion Is Associated with ADAMTS2 Variants and Reduced Expression in a Familial Case.

Skeletal Class III malocclusion with maxillary deficiency is a severe maxillofacial disease with unclear pathogenic mechanisms. We recruited a Han Chinese family who was clinically diagnosed with skeletal Class III malocclusion and maxillary deficiency. Using whole exome sequencing, a missense variant in ADAMTS2 (NM_014244: c.3506G>T: p.G1169V) was identified and predicted as deleterious by in silico tools. We also found ADAMTS2 variants associated with deficient maxillary development in a cohort. ADAMTS2 expression in HEK293 cells showed significant decrease due to the variant, which was also consistent in dental pulp stem cells from the proband and a healthy control. In the adamts2-knockdown zebrafish model, the length and width of the ethmoid plate, as well as the length of the palatoquadrate became significantly shorter than the control group (p < 0.001), while there was no significant difference in the length and width of the mandible. The expression of Sox3, which was required in early embryonic craniofacial development, was significantly downregulated in the adamts2-knockdown zebrafish embryos. Bioinformatic and cellular studies showed that the decreased expression of ADAMTS2 may inhibit downstream ErbB signaling pathway transduction and restrain subsequent osteogenesis in human adult mesenchymal stromal cells. Collectively, these data showed that ADAMTS2 (c.3506G>T: p.G1169V) may confer susceptibility to risk of skeletal Class III malocclusion with maxillary deficiency.

Identification of novel susceptibility loci for non-syndromic cleft lip with or without cleft palate.

Although several genome-wide association studies (GWAS) of non-syndromic cleft lip with or without cleft palate (NSCL/P) have been reported, more novel association signals are remained to be exploited. Here, we performed an in-depth analysis of our previously published Chinese GWAS cohort study with replication in an extra dbGaP case-parent trios and another in-house Nanjing cohort, and finally identified five novel significant association signals (rs11119445: 3' of SERTAD4, P = 6.44 × 10-14 ; rs227227 and rs12561877: intron of SYT14, P = 5.02 × 10-13 and 2.80 × 10-11 , respectively; rs643118: intron of TRAF3IP3, P = 4.45 × 10-6 ; rs2095293: intron of NR6A1, P = 2.98 × 10-5 ). The mean (standard deviation) of the weighted genetic risk score (wGRS) from these SNPs was 1.83 (0.65) for NSCL/P cases and 1.58 (0.68) for controls, respectively (P = 2.67 × 10-16 ). Rs643118 was identified as a shared susceptible factor of NSCL/P among Asians and Europeans, while rs227227 may contribute to the risk of NSCL/P as well as NSCPO. In addition, sertad4 knockdown zebrafish models resulted in down-regulation of sox2 and caused oedema around the heart and mandibular deficiency, compared with control embryos. Taken together, this study has improved our understanding of the genetic susceptibility to NSCL/P and provided further clues to its aetiology in the Chinese population.