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Experimental & Molecular Medicine Jul 2024The asymmetric division of stem cells permits the maintenance of the cell population and differentiation for harmonious progress. Developing mouse incisors allows...
The asymmetric division of stem cells permits the maintenance of the cell population and differentiation for harmonious progress. Developing mouse incisors allows inspection of the role of the stem cell niche to provide specific insights into essential developmental phases. Microtubule-associated serine/threonine kinase family member 4 (Mast4) knockout (KO) mice showed abnormal incisor development with low hardness, as the size of the apical bud was decreased and preameloblasts were shifted to the apical side, resulting in amelogenesis imperfecta. In addition, Mast4 KO incisors showed abnormal enamel maturation, and stem cell maintenance was inhibited as amelogenesis was accelerated with Wnt signal downregulation. Distal-Less Homeobox 3 (DLX3), a critical factor in tooth amelogenesis, is considered to be responsible for the development of amelogenesis imperfecta in humans. MAST4 directly binds to DLX3 and induces phosphorylation at three residues within the nuclear localization site (NLS) that promotes the nuclear translocation of DLX3. MAST4-mediated phosphorylation of DLX3 ultimately controls the transcription of DLX3 target genes, which are carbonic anhydrase and ion transporter genes involved in the pH regulation process during ameloblast maturation. Taken together, our data reveal a novel role for MAST4 as a critical regulator of the entire amelogenesis process through its control of Wnt signaling and DLX3 transcriptional activity.
PubMed: 38945953
DOI: 10.1038/s12276-024-01264-5 -
International Journal of Molecular... Jun 2024Epigenetic modulation, including histone modification, alters gene expression and controls cell fate. Histone deacetylases (HDACs) are identified as important regulators...
Epigenetic modulation, including histone modification, alters gene expression and controls cell fate. Histone deacetylases (HDACs) are identified as important regulators of dental pulp cell (DPC) mineralisation processes. Currently, there is a paucity of information regarding the nature of histone modification and HDAC expression in the dentine-pulp complex during dentinogenesis. The aim of this study was to investigate post-translational histone modulation and HDAC expression during DPC mineralisation and the expression of Class I/II HDACs during tooth development and in adult teeth. HDAC expression (isoforms -1 to -6) was analysed in mineralising primary rat DPCs using qRT-PCR and Western blot with mass spectrometry being used to analyse post-translational histone modifications. Maxillary molar teeth from postnatal and adult rats were analysed using immunohistochemical (IHC) staining for HDACs (1-6). HDAC-1, -2, and -4 protein expression increased until days 7 and 11, but decreased at days 14 and 21, while other HDAC expression increased continuously for 21 days. The Class II mineralisation-associated HDAC-4 was strongly expressed in postnatal sample odontoblasts and DPCs, but weakly in adult teeth, while other Class II HDACs (-5, -6) were relatively strongly expressed in postnatal DPCs and adult odontoblasts. Among Class I HDACs, HDAC-1 showed high expression in postnatal teeth, notably in ameloblasts and odontoblasts. HDAC-2 and -3 had extremely low expression in the rat dentine-pulp complex. Significant increases in acetylation were noted during DPC mineralisation processes, while trimethylation H3K9 and H3K27 marks decreased, and the HDAC-inhibitor suberoylanilide hydroxamic acid (SAHA) enhanced H3K27me3. These results highlight a dynamic alteration in histone acetylation during mineralisation and indicate the relevance of Class II HDAC expression in tooth development and regenerative processes.
Topics: Animals; Acetylation; Rats; Histone Deacetylases; Dentinogenesis; Dentin; Dental Pulp; Protein Processing, Post-Translational; Histones; Molar; Odontoblasts; Male
PubMed: 38928274
DOI: 10.3390/ijms25126569 -
F1000Research 2022Various stemness markers (SOX2, OCT4, and NANOG) have been studied in odontogenic cysts and tumors. However, studies on SALL4 having similar properties of stemness has...
BACKGROUND
Various stemness markers (SOX2, OCT4, and NANOG) have been studied in odontogenic cysts and tumors. However, studies on SALL4 having similar properties of stemness has not been documented. Additionally, insight into fascin as a migratory molecule is less explored. In this study, the expression of SALL4 and fascin were evaluated in ameloblastoma, adenomatoid odontogenic tumor (AOT), odontogenic keratocyst (OKC), dentigerous cyst (DC), radicular cyst (RC), and calcifying odontogenic cyst (COC).
METHODS
Semi-quantitative analysis of fascin and SALL4 immuno-positive cells was done in a total of 40 cases of ameloblastoma (11 plexiform, 12 follicular, 12 unicystic, and 5 desmoplastic) variants, 6 cases of AOT, 15 each of OKC, DC, RC and 5 of COC. Chi-square test was applied to evaluate the association between SALL4 and fascin expression in odontogenic cysts and tumors.
RESULTS
Fascin immunopositivity was observed in peripheral ameloblast-like cells, and weak or absent in stellate reticulum-like cells. A moderate to weak immune-reactivity to SALL4 was observed in the cytoplasm of ameloblastoma, epithelial cells of dentigerous and radicular cysts, having a marked inflammatory infiltrate, which is an interesting observation. COC and AOT had negative to weak expressions. No recurrence has been reported.
CONCLUSIONS
Expression of fascin in ameloblastomas elucidate their role in motility and localized invasion. Its expression in less aggressive lesions like DC, COC, AOT will incite to explore the other functional properties of fascin. SALL4 expression in the cytoplasm of odontogenic cysts and tumors may represent inactive or mutant forms which requires further validation.
Topics: Humans; Transcription Factors; Microfilament Proteins; Odontogenic Cysts; Carrier Proteins; Immunohistochemistry; Ameloblastoma; Odontogenic Tumors; Biomarkers, Tumor
PubMed: 38895097
DOI: 10.12688/f1000research.126091.3 -
International Journal of Molecular... Jun 2024mutations cause X-linked amelogenesis imperfecta (AI), known as AI types IE, IIB, and IIC in Witkop's classification, characterized by hypoplastic (reduced thickness)...
mutations cause X-linked amelogenesis imperfecta (AI), known as AI types IE, IIB, and IIC in Witkop's classification, characterized by hypoplastic (reduced thickness) and/or hypomaturation (reduced hardness) enamel defects. In this study, we conducted whole exome analyses to unravel the disease-causing mutations for six AI families. Splicing assays, immunoblotting, and quantitative RT-PCR were conducted to investigate the molecular and cellular effects of the mutations. Four pathogenic variants (NM_182680.1:c.2T>C; c.29T>C; c.77del; c.145-1G>A) and a whole gene deletion (NG_012494.2:g.307534_403773del) were identified. The affected individuals exhibited enamel malformations, ranging from thin, poorly mineralized enamel with a "snow-capped" appearance to severe hypoplastic defects with minimal enamel. The c.145-1G>A mutation caused a -1 frameshift (NP_001133.1:p.Val35Cysfs*5). Overexpression of c.2T>C and c.29T>C demonstrated that mutant amelogenin proteins failed to be secreted, causing elevated endoplasmic reticulum stress and potential cell apoptosis. This study reveals a genotype-phenotype relationship for -associated AI: While amorphic mutations, including large deletions and 5' truncations, of cause hypoplastic-hypomaturation enamel with snow-capped teeth (AI types IIB and IIC) due to a complete loss of gene function, neomorphic variants, including signal peptide defects and 3' truncations, lead to severe hypoplastic/aplastic enamel (AI type IE) probably caused by "toxic" cellular effects of the mutant proteins.
Topics: Amelogenesis Imperfecta; Humans; Amelogenin; Male; Female; Genetic Association Studies; Mutation; Pedigree; Phenotype; Child; Endoplasmic Reticulum Stress; Genotype; Exome Sequencing
PubMed: 38892321
DOI: 10.3390/ijms25116132 -
STAR Protocols Jun 2024Adult humans cannot regenerate the enamel-forming cell type, ameloblasts. Hence, human induced pluripotent stem cell (hiPSC)-derived ameloblasts are valuable for...
Adult humans cannot regenerate the enamel-forming cell type, ameloblasts. Hence, human induced pluripotent stem cell (hiPSC)-derived ameloblasts are valuable for investigating tooth development and regeneration. Here, we present a protocol for generating three-dimensional induced early ameloblasts (ieAMs) utilizing serum-free media and growth factors. We describe steps for directing hiPSCs toward oral epithelium and then toward ameloblast fate. These cells can form suspended early ameloblast organoids. This approach is critical for understanding, treating, and promoting regeneration in diseases like amelogenesis imperfecta. For complete details on the use and execution of this protocol, please refer to Alghadeer et al..
Topics: Ameloblasts; Humans; Culture Media, Serum-Free; Induced Pluripotent Stem Cells; Cell Culture Techniques; Intercellular Signaling Peptides and Proteins; Cell Differentiation; Cells, Cultured
PubMed: 38824640
DOI: 10.1016/j.xpro.2024.103100 -
Genes & Diseases Sep 2024
PubMed: 38756354
DOI: 10.1016/j.gendis.2023.101103 -
ACS Nano Apr 2024Teeth exemplify architectures comprising an interplay of inorganic and organic constituents, resulting in sophisticated natural composites. Rodents (Rodentia) showcase...
Teeth exemplify architectures comprising an interplay of inorganic and organic constituents, resulting in sophisticated natural composites. Rodents (Rodentia) showcase extraordinary adaptations, with their continuously growing incisors surpassing human teeth in functional and structural optimizations. In this study, employing state-of-the-art direct atomic-scale imaging and nanoscale spectroscopies, we present compelling evidence that the release of material from ameloblasts and the subsequent formation of iron-rich enamel and surface layers in the constantly growing incisors of rodents are complex orchestrated processes, intricately regulated and independent of environmental factors. The synergistic fusion of three-dimensional tomography and imaging techniques of etched rodent́s enamel unveils a direct correlation between the presence of pockets infused with ferrihydrite-like material and the acid resistant properties exhibited by the iron-rich enamel, fortifying it as an efficient protective shield. Moreover, observations using optical microscopy shed light on the role of iron-rich enamel as a microstructural element that acts as a path for color transmission, although the native color remains indistinguishable from that of regular enamel, challenging the prevailing paradigms. The redefinition of "pigmented enamel" to encompass ferrihydrite-like infusion in rodent incisors reshapes our perception of incisor microstructure and color generation. The functional significance of acid-resistant iron-rich enamel and the understanding of the underlying coloration mechanism in rodent incisors have far-reaching implications for human health, development of potentially groundbreaking dental materials, and restorative dentistry. These findings enable the creation of an entirely different class of dental biomaterials with enhanced properties, inspired by the ingenious designs found in nature.
Topics: Animals; Dental Enamel; Ferric Compounds; Rats; Color; Mice; Incisor; Tooth
PubMed: 38629732
DOI: 10.1021/acsnano.4c00578 -
Regenerative Therapy Dec 2024Understanding the composition and function of cells constituting tissues and organs is vital for unraveling biological processes. Single-cell analysis has allowed us to... (Review)
Review
Understanding the composition and function of cells constituting tissues and organs is vital for unraveling biological processes. Single-cell analysis has allowed us to move beyond traditional methods of categorizing cell types. This innovative technology allows the transcriptional and epigenetic profiling of numerous individual cells, leading to significant insights into the development, homeostasis, and pathology of various organs and tissues in both animal models and human samples. In this review, we delve into the outcomes of major investigations using single-cell transcriptomics to decipher the cellular composition of mammalian teeth and periodontal tissues. The recent single-cell transcriptome-based studies have traced in detail the dental epithelium-ameloblast lineage and dental mesenchyme lineages in the mouse incisors and the tooth germ of both mice and humans; unraveled the microenvironment, the identity of niche cells, and cellular intricacies in the dental pulp; shed light on the molecular mechanisms orchestrating root formation; and characterized cellular dynamics of the periodontal ligament. Additionally, cellular components in dental pulps were compared between healthy and carious teeth at a single-cell level. Each section of this review contributes to a comprehensive understanding of tooth biology, offering valuable insights into developmental processes, niche cell identification, and the molecular secrets of the dental environment.
PubMed: 38596822
DOI: 10.1016/j.reth.2024.03.023 -
Heliyon Mar 2024The junctional epithelium (JE) serves a crucial protective role in the periodontium. High glucose-related aging results in accelerated barrier dysfunction of the...
The junctional epithelium (JE) serves a crucial protective role in the periodontium. High glucose-related aging results in accelerated barrier dysfunction of the gingival epithelium, which may be associated with diabetic periodontitis. Metformin, an oral hypoglycemic therapeutic, has been proposed as a anti-aging agent. This study aimed to clarify the effect of metformin on diabetic periodontitis and explore its mechanism in ameliorating senescence of JE during hyperglycemia. The db/db mice was used as a diabetic model mice and alterations in the periodontium were observed by hematoxylin-eosin staining and immunohistochemistry. An ameloblast-like cell line (ALC) was cultured with high glucose to induce senescence. Cellular senescence and oxidative stress were evaluated by SA-β-gal staining and Intracellular reactive oxygen species (ROS) levels. Senescence biomarkers, P21 and P53, and autophagy markers, LC3-II/LC3-I, were measured by western blotting and quantitative real-time PCR. To construct a stable SIRT1 (Sirtuin 1) overexpression cell line, we transfected ALCs with lentiviral vectors overexpressing the mouse SIRT1 gene. Cellular senescence was increased in the JE of db/db mice and the periodontium was destroyed, which could be alleviated by metformin. Moreover, oxidative stress and cellular senescence in a high glucose environment were reduced by metformin in assays. The autophagy inhibitor 3-MA and SIRT1 inhibitor EX-527 could dampen the effects of metformin. Overexpression of SIRT1 resulted in increased autophagy and decreased oxidative stress and cellular senescence. Meanwhile, AMPK (AMP-activated protein kinase) inhibition reversed the anti-senescence effects of metformin. Overall, these results suggest that metformin alleviates periodontal damage in db/db mice and cellular senescence in ALCs under high glucose conditions via the AMPK/SIRT1/autophagy pathway.
PubMed: 38496895
DOI: 10.1016/j.heliyon.2024.e27478 -
Journal of Medical Genetics Jun 2024Plexins are large transmembrane receptors for the semaphorin family of signalling proteins. Semaphorin-plexin signalling controls cellular interactions that are critical...
BACKGROUND
Plexins are large transmembrane receptors for the semaphorin family of signalling proteins. Semaphorin-plexin signalling controls cellular interactions that are critical during development as well as in adult life stages. Nine plexin genes have been identified in humans, but despite the apparent importance of plexins in development, only biallelic and variants have so far been associated with Mendelian genetic disease.
METHODS
Eight individuals from six families presented with a recessively inherited variable clinical condition, with core features of amelogenesis imperfecta (AI) and sensorineural hearing loss (SNHL), with variable intellectual disability. Probands were investigated by exome or genome sequencing. Common variants and those unlikely to affect function were excluded. Variants consistent with autosomal recessive inheritance were prioritised. Variant segregation analysis was performed by Sanger sequencing. RNA expression analysis was conducted in C57Bl6 mice.
RESULTS
Rare biallelic pathogenic variants in plexin B2 (), a large transmembrane semaphorin receptor protein, were found to segregate with disease in all six families. The variants identified include missense, nonsense, splicing changes and a multiexon deletion. expression was detected in differentiating ameloblasts.
CONCLUSION
We identify rare biallelic pathogenic variants in as a cause of a new autosomal recessive, phenotypically diverse syndrome with AI and SNHL as core features. Intellectual disability, ocular disease, ear developmental abnormalities and lymphoedema were also present in multiple cases. The variable syndromic human phenotype overlaps with that seen in knockout mice, and, together with the rarity of human variants, may explain why pathogenic variants in have not been reported previously.
Topics: Humans; Animals; Male; Female; Mice; Intellectual Disability; Pedigree; Amelogenesis Imperfecta; Receptors, Cell Surface; Nerve Tissue Proteins; Alleles; Child; Hearing Loss; Hearing Loss, Sensorineural; Adult; Mutation; Adolescent; Child, Preschool; Phenotype
PubMed: 38458752
DOI: 10.1136/jmg-2023-109728