Activating PIK3CA mutation promotes osteogenesis of bone marrow mesenchymal stem cells in macrodactyly

Photothermal switch by gallic acid-calcium grafts synthesized by coordination chemistry for sequential treatment of bone tumor and regeneration

The residual bone tumor and defects which is caused by surgical therapy of bone tumor is a major and important problem in clinicals. And the sequential treatment for irradiating residual tumor and repairing bone defects has wildly prospects. In this study, we developed a general modification strategy by gallic acid (GA)-assisted coordination chemistry to prepare black calcium-based materials, which combines the sequential photothermal therapy of bone tumor and bone defects. The GA modification endows the materials remarkable photothermal properties. Under the near-infrared (NIR) irradiation with different power densities, the black GA-modified bone matrix (GBM) did not merely display an excellent performance in eliminating bone tumor with high temperature, but showed a facile effect of the mild-heat stimulation to accelerate bone regeneration. GBM can efficiently regulate the microenvironments of bone regeneration in a spatial-temporal manner, including inflammation/immune response, vascularization and osteogenic differentiation. Meanwhile, the integrin/PI3K/Akt signaling pathway of bone marrow mesenchymal stem cells (BMSCs) was revealed to be involved in the effect of osteogenesis induced by the mild-heat stimulation. The outcome of this study not only provides a serial of new multifunctional biomaterials, but also demonstrates a general strategy for designing novel blacked calcium-based biomaterials with great potential for clinical use.

Synthetic nanointerfacial bioengineering of Ti implants: on-demand regulation of implant-bone interactions for enhancing osseointegration

Titanium and its alloys are the most commonly used biometals for developing orthopedic implants to treat various forms of bone fractures and defects, but their clinical performance is still challenged by the unfavorable mechanical and biological interactions at the implant-tissue interface, which substantially impede bone healing at the defects and reduce the quality of regenerated bones. Moreover, the impaired osteogenesis capacity of patients under certain pathological conditions such as diabetes and osteoporosis may further impair the osseointegration of Ti-based implants and increase the risk of treatment failure. To address these issues, various modification strategies have been developed to regulate the implant-bone interactions for improving bone growth and remodeling in situ. In this review, we provide a comprehensive analysis on the state-of-the-art synthetic nanointerfacial bioengineering strategies for designing Ti-based biofunctional orthopedic implants, with special emphasis on the contributions to (1) promotion of new bone formation and binding at the implant-bone interface, (2) bacterial elimination for preventing peri-implant infection and (3) overcoming osseointegration resistance induced by degenerative bone diseases. Furthermore, a perspective is included to discuss the challenges and potential opportunities for the interfacial engineering of Ti implants in a translational perspective. Overall, it is envisioned that the insights in this review may guide future research in the area of biometallic orthopedic implants for improving bone repair with enhanced efficacy and safety.

Revealing the novel metabolism-related genes in the ossification of the ligamentum flavum based on whole transcriptomic data

Backgrounds

The ossification of the ligamentum flavum (OLF) is one of the major causes of thoracic myelopathy. Previous studies indicated there might be a potential link between metabolic disorder and pathogenesis of OLF. The aim of this study was to determine the potential role of metabolic disorder in the pathogenesis of OLF using the strict bioinformatic workflow for metabolism-related genes and experimental validation.

Methods

A series of bioinformatic approaches based on metabolism-related genes were conducted to compare the metabolism score between OLF tissues and normal ligamentum flavum (LF) tissues using the single sample gene set enrichment analysis. The OLF-related and metabolism-related differentially expressed genes (OMDEGs) were screened out, and the biological functions of OMDEGs were explored, including the Gene Ontology enrichment analysis, Kyoto Encyclopedia of Genes and Genomes enrichment analysis, and protein-protein interaction. The competing endogenous RNA (ceRNA) network based on pairs of miRNA-hub OMDEGs was constructed. The correlation analysis was conducted to explore the potential relationship between metabolic disorder and immunity abnormality in OLF. In the end, the cell experiments were performed to validate the roles of GBE1 and TNF-α in the osteogenic differentiation of LF cells.

Results

There was a significant difference of metabolism score between OLF tissues and normal LF tissues. Forty-nine OMDEGs were screened out and their biological functions were determined. The ceRNA network containing three hub OMDEGs and five differentially expressed miRNAs (DEmiRNAs) was built. The correlation analysis between hub OMDEGs and OLF-related infiltrating immune cells indicated that metabolic disorder might contribute to the OLF via altering the local immune status of LF tissues. The cell experiments determined the important roles of GBE1 expression and TNF-α in the osteogenic differentiation of LF cells.

Conclusions

This research, for the first time, preliminarily illustrated the vital role of metabolic disorder in the pathogenesis of OLF using strict bioinformatic algorithms and experimental validation for metabolism-related genes, which could provide new insights for investigating disease mechanism and screening effective therapeutic targets of OLF in the future.

Direct activation of PI3K in osteoblasts and osteocytes strengthens murine bone through sex-specific actions on cortical surfaces

Intracellular phosphoinositide 3-kinase (PI3K) signaling is activated by multiple bone-active receptors. Genetic mutations activating PI3K signaling are associated with clinical syndromes of tissue overgrowth in multiple organs, often including the skeleton. While one formation is increased by removing the PI3K inhibitor (phosphatase and TENsin homolog deleted on chromosome 10 (PTEN)), the effect of direct PI3K activation in the osteoblast lineage has not been reported. We introduced a known gain-of-function mutation in Pik3ca, the gene encoding the p110α catalytic subunit of PI3K, in osteocytes and late osteoblasts using the dentin matrix protein-1 Cre (Dmp1Cre) mouse and assessed the skeletal phenotype. Femur shape was grossly normal, but cortical thickness was significantly greater in both male and female Dmp1Cre.Pik3caH1047R mice, leading to almost doubled bone strength at 12 wk of age. Both sexes had smaller marrow areas from 6 wk of age. Female mice also exhibited greater cross-sectional area, which continued to increase until 24 wk of age, resulting in a further increase in bone strength. Although both male and female mice had increased endocortical mineralizing surface, only female mice had increased periosteal mineralizing surface. The bone formed in the Dmp1Cre.Pik3caH1047R mice showed no increase in intracortical remodeling nor any defect in cortical bone consolidation. In contrast, on both endocortical and periosteal surfaces, there was more lamellar bone formation, including highly organized osteocyte networks extending along the entire surface at a greater thickness than in control mice. In conclusion, direct activation of PI3Kα in cells targeted by Dmp1Cre leads to high cortical bone mass and strength with abundant lamellar cortical bone in female and male mice with no increase in intracortical remodeling. This differs from the effect of PTEN deletion in the same cells, suggesting that activating PI3Kα in osteoblasts and osteocytes may be a more suitable target to promote formation of lamellar bone.

PIK3CA mutations enhance the adipogenesis of ADSCs in facial infiltrating lipomatosis through TRPV1

Facial infiltrating lipomatosis (FIL) is a congenital disorder. The pathogenesis of FIL is associated with PIK3CA mutations, but the underlying mechanisms remain undetermined. We found that the adipose tissue in FIL demonstrated adipocytes hypertrophy and increased lipid accumulation. All adipose-derived mesenchymal stem cells from FIL (FIL-ADSCs) harbored PIK3CA mutations. Moreover, FIL-ADSCs exhibited a greater capacity for adipogenesis. Knockdown of PIK3CA resulted in a reduction in the adipogenic potential of FIL-ADSCs. Furthermore, WX390, a dual-target PI3K/mTOR inhibitor, was found to impede PIK3CA-mediated adipogenesis both in vivo and in vitro. RNA sequencing (RNA-seq) revealed that the expression of transient receptor potential vanilloid subtype 1 (TRPV1) was upregulated after PI3K pathway inhibition, and overexpression or activation of TRPV1 both inhibited adipogenesis. Our study showed that PIK3CA mutations promoted adipogenesis in FIL-ADSCs and this effect was achieved by suppressing TPRV1. Pathogenesis experiments suggested that WX390 may serve as an agent for the treatment of FIL.

ZIF-8-Modified Black Phosphorus Nanosheets Incorporated into Injectable Dual-Component Hydrogels for Enhanced Photothermal Antibacterial and Osteogenic Activities

The development of growth factor-free biomaterials for bone tissue regeneration with anti-infection and anti-inflammatory activities remains challenging. Black phosphorus nanosheets (BPNs), with distinctive attributes, including photothermal conversion and calcium ion chelation, offer potential for use in bone tissue engineering and infection prevention. However, BPNs are prone to oxidation and degradation in aqueous environments, and methods to stabilize BPNs for long-term bone repair remain insufficient. Herein, zeolitic imidazolate framework-8 (ZIF-8) was used to stabilize BPNs via in situ crystallization onto the surface of BPNs (BP@ZIF-8 nanocomposite). A novel injectable dual-component hydrogel comprising gelatin methacryloyl (GelMA) and methacrylate-modified hyaluronic acid (HAMA) was used as a BP@ZIF-8 nanocomposite carrier (GelMA/HAMA/BP@ZIF-8). The BP@ZIF-8 nanocomposite could effectively protect internal BPNs from oxidation and enhance the long-term photothermal performance of the hydrogel in both in vitro and in vivo settings. The GelMA/HAMA/BP@ZIF-8 hydrogel was injectable and exhibited outstanding performance for photothermal conversion, mechanical strength, and biodegradability, as well as excellent photothermal antibacterial activity against Staphylococcus aureus and Escherichia coli in vitro and in an in vivo rat model. The GelMA/HAMA/BP@ZIF-8 hydrogel also provided a microenvironment conducive to osteogenic differentiation, promoting the transformation of M2 macrophages and inhibiting inflammatory responses. Furthermore, the hydrogel promoted bone regeneration and had a synergistic effect with near-infrared irradiation in a rat skull-defect model. Transcriptome sequencing analysis revealed that the PI3K-AKT- and calcium-signaling pathways may be involved in promoting osteogenic differentiation induced by the GH-BZ hydrogel. This study presents an innovative, multifaceted solution to the challenges of bone tissue regeneration with antibacterial and anti-inflammatory effects, providing insights into the design of smart biomaterials with dual therapeutic capabilities.

Macrodactyly

Macrodactyly is a rare congenital limb difference manifesting as an overgrowth of one or more fingers or toes. The pathological process affects all tissues of the ray in the hand or foot. The enlargement can significantly alter the limb's appearance and impair its function. The role of a pediatrician is to distinguish isolated macrodactyly from syndromic conditions (including PIK3CA-Related Overgrowth Spectrum) or mimicking conditions to enable early interdisciplinary consultation and treatment planning. The psychological stigma associated with this often disfiguring condition necessitates support for patients and their family. We present a practical guide for physicians who might be the first to raise suspicion of macrodactyly and initiate further diagnostics to achieve adequate treatment and support for children and caregivers.

Enhancing postmenopausal osteoporosis: a study of KLF2 transcription factor secretion and PI3K-Akt signaling pathway activation by PIK3CA in bone marrow mesenchymal stem cells

Introduction

Mesenchymal stem cells can develop into osteoblasts, making them a promising cell-based osteoporosis treatment. Despite their therapeutic potential, their molecular processes are little known. Bioinformatics and experimental analysis were used to determine the molecular processes of bone marrow mesenchymal stem cell (BMSC) therapy for postmenopausal osteoporosis (PMO).

Material and methods

We used weighted gene co-expression network analysis (WGCNA) to isolate core gene sets from two GEO microarray datasets (GSE7158 and GSE56815). GeneCards found PMO-related genes. GO, KEGG, Lasso regression, and ROC curve analysis refined our candidate genes. Using the GSE105145 dataset, we evaluated KLF2 expression in BMSCs and examined the link between KLF2 and PIK3CA using Pearson correlation analysis. We created a protein-protein interaction network of essential genes involved in osteoblast differentiation and validated the functional roles of KLF2 and PIK3CA in BMSC osteoblast differentiation in vitro.

Results

We created 6 co-expression modules from 10 419 differentially expressed genes (DEGs). PIK3CA, the key gene in the PI3K-Akt pathway, was among 197 PMO-associated DEGs. KLF2 also induced PIK3CA transcription in PMO. BMSCs also expressed elevated KLF2. BMSC osteoblast differentiation involved the PI3K-Akt pathway. In vitro, KLF2 increased PIK3CA transcription and activated the PI3K-Akt pathway to differentiate BMSCs into osteoblasts.

Conclusions

BMSCs release KLF2, which stimulates the PIK3CA-dependent PI3K-Akt pathway to treat PMO. Our findings illuminates the involvement of KLF2 and the PI3K-Akt pathway in BMSC osteoblast development, which may lead to better PMO treatments.

BMP9 induces osteogenic differentiation through up-regulating LGR4 via the mTORC1/Stat3 pathway in mesenchymal stem cells

Bone defects and non-union are prevalent in clinical orthopedy, and the outcomes of current treatments are often suboptimal. Bone tissue engineering offers a promising approach to treating these conditions effectively. Bone morphogenetic protein 9 (BMP9) can commit mesenchymal stem cells to osteogenic lineage, and a knowledge of the underlying mechanisms may help advance the field of bone tissue engineering. Leucine-rich repeats containing G protein-coupled receptor 4 (LGR4), a member of G protein-coupled receptors, is essential for modulating bone development. This study is aimed at investigating the impact of LGR4 on BMP9-induced osteogenesis in mesenchymal stem cells as well as the underlying mechanisms. Bone marrow stromal cells from BMP9-knockout mice exhibited diminished LGR4 expression, and exogenous LGR4 clearly restored the impaired osteogenic potency of the bone marrow stromal cells. Furthermore, LGR4 expression was increased by BMP9 in C3H10T1/2 cells. LGR4 augmented the benefits of BMP9-induced osteogenic markers and bone formation, whereas LGR4 inhibition restricted these effects. Meanwhile, the BMP9-induced lipogenic markers were increased by LGR4 inhibition. The protein levels of Raptor and p-Stat3 were elevated by BMP9. Raptor knockdown or p-Stat3 suppression attenuated the osteoblastic markers and LGR4 expression brought on by BMP9. LGR4 significantly reversed the blocking effect of Raptor knockdown or p-Stat3 suppression on the BMP9-induced osteoblastic markers. Raptor interacts with p-Stat3, and p-Stat3 activates the LGR4 promoter activity. In conclusion, LGR4 boosts BMP9 osteoblastic potency in mesenchymal stem cells, and BMP9 may up-regulate LGR4 via the mTORC1/Stat3 signal activation.

Pten knockout in mouse preosteoblasts leads to changes in bone turnover and strength

Bone development and remodeling are controlled by the phosphoinositide-3-kinase (Pi3k) signaling pathway. We investigated the effects of downregulation of phosphatase and tensin homolog (Pten), a negative regulator of Pi3k signaling, in a mouse model of Pten deficiency in preosteoblasts. We aimed to identify mechanisms that are involved in the regulation of bone turnover and are linked to bone disorders. Femora, tibiae, and bone marrow stromal cells (BMSCs) isolated from mice with a conditional deletion of Pten (Pten cKO) in Osterix/Sp7-expressing osteoprogenitor cells were compared to Cre-negative controls. Bone phenotyping was performed by μCT measurements, bone histomorphometry, quantification of bone turnover markers CTX and procollagen type 1 N propeptide (P1NP), and three-point bending test. Proliferation of BMSCs was measured by counting nuclei and Ki-67-stained cells. In vitro, osteogenic differentiation capacity was determined by ALP staining, as well as by detecting gene expression of osteogenic markers. BMSCs from Pten cKO mice were functionally different from control BMSCs. Osteogenic markers were increased in BMSCs derived from Pten cKO mice, while Pten protein expression was lower and Akt phosphorylation was increased. We detected a higher trabecular bone volume and an altered cortical bone morphology in Pten cKO bones with a progressive decrease in bone and tissue mineral density. Pten cKO bones displayed fewer osteoclasts and more osteoblasts (P = .00095) per trabecular bone surface and a higher trabecular bone formation rate. Biomechanical analysis revealed a significantly higher bone strength (P = .00012 for males) and elasticity of Pten cKO femora. On the cellular level, both proliferation and osteogenic differentiation capacity of Pten cKO BMSCs were significantly increased compared to controls. Our findings suggest that Pten knockout in osteoprogenitor cells increases bone stability and elasticity by increasing trabecular bone mass and leads to increased proliferation and osteogenic differentiation of BMSCs.

Rehabilitation exercise-driven symbiotic electrical stimulation system accelerating bone regeneration

Electrical stimulation can effectively accelerate bone healing. However, the substantial size and weight of electrical stimulation devices result in reduced patient benefits and compliance. It remains a challenge to establish a flexible and lightweight implantable microelectronic stimulator for bone regeneration. Here, we use self-powered technology to develop an electric pulse stimulator without circuits and batteries, which removes the problems of weight, volume, and necessary rigid packaging. The fully implantable bone defect electrical stimulation (BD-ES) system combines a hybrid tribo/piezoelectric nanogenerator to provide biphasic electric pulses in response to rehabilitation exercise with a conductive bioactive hydrogel. BD-ES can enhance multiple osteogenesis-related biological processes, including calcium ion import and osteogenic differentiation. In a rat model of critical-sized femoral defects, the bone defect was reversed by electrical stimulation therapy with BD-ES and subsequent bone mineralization, and the femur completely healed within 6 weeks. This work is expected to advance the development of symbiotic electrical stimulation therapy devices without batteries and circuits.

AKT from dental epithelium to papilla promotes odontoblast differentiation

Epithelial-mesenchymal interactions occur during tooth development. The dental epithelium (DE) is regarded as the signal center that regulates tooth morphology. However, the mechanism by which DE regulates the differentiation of mesenchyme-derived dental papilla (DP) into odontoblasts remains unclear. Using miniature pigs as a model, we analyzed the expression profiles of the DE and DP during odontoblast differentiation using high-throughput RNA sequencing. The phosphatidylinositol-3-kinase (PI3K)/AKT pathway is one of the most enriched pathways in both DE and DP. The PI3K/AKT pathway was first activated in the inner enamel epithelium but not in the DP on embryonic day 50. This pathway was then activated in the odontoblast layer on embryonic day 60. We showed that AKT activation promoted odontoblast differentiation of DP cells. We further demonstrated that activation of PI3K/AKT signaling in the DE effectively increased the expression levels of AKT and dentin sialophosphoprotein in DP cells. Additionally, we found that DE cells secreted collagen type IV alpha 6 chain (COL4A6) downstream of epithelial AKT signaling to positively regulate mesenchymal AKT levels. Therefore, our data suggest that PI3K/AKT signaling from the DE to the DP promotes odontoblast differentiation via COL4A6 secretion.

Resistin targets TAZ to promote osteogenic differentiation through PI3K/AKT/mTOR pathway

Osteogenic differentiation (OD) of bone marrow mesenchymal stem cells (BMSCs) contributes significantly to the regeneration of bone defects. Resistin, an adipose tissue-specific secretory factor, has been shown to involve many different functions, including metabolism, inflammation, cancer, and bone remodeling. However, the effects and mechanisms of resistin on OD of BMSCs remain unclear. Herein, we demonstrated that resistin was highly expressed in BMSCs with OD. Upregulation of resistin contributed to the progression of OD of BMSCs by activating PI3K/AKT/mTOR signaling pathway. In addition, resistin facilitated OD by targeting transcriptional co-activator with PDZ-binding motif (TAZ). In a rat femoral condyle bone defect model, local injection of resistin significantly promoted bone repair and improved bone formation. This work contributes to better understanding the mechanism of resistin directly involved in the OD and might provide a new therapeutic strategy for bone defect regeneration.

Mechanisms underlying the therapeutic effects of isoflavones isolated from chickpea sprouts in treating osteoporosis based on network pharmacology

Osteoporosis is a systemic bone disease that is caused by multiple factors that lead to an imbalance in bone metabolism. Isoflavones can prevent and treat osteoporosis by regulating bone metabolism through a variety of pathways. The germination of chickpeas can significantly increase their isoflavone contents. However, the use of isoflavones isolated from chickpea sprouts (ICS) to prevent and treat osteoporosis by regulating bone metabolism has not been widely studied. In vivo experimental studies in ovariectomized rats showed that ICS significantly improved femoral bone mineral density (BMD) and trabecular structure, with effects similar to raloxifene. Furthermore, the chemical composition of ICS as well as the targets and signalling pathways its regulates in the prevention and treatment of osteoporosis were predicted by network pharmacological studies. ICS with drug-like properties were identified by Lipinski's 5 principles, and intersecting targets of isoflavones with osteoporosis were identified. The overlapping targets were analysed by PPI, GO and KEGG analyses, and the possible key targets, signalling pathways and biological processes by which ICS treats osteoporosis were predicted; the prediction results were verified by molecular docking technology. The results showed that ICS could play an important role in the treatment of osteoporosis through "multicomponent, multitarget and multipathway" mechanisms, and the MAKP, NF-kB and ER-related signalling pathways may be important pathways by which ICS regulates osteoporosis; these findings provide a new theoretical basis for further experimental studies.

Updates on Diagnosis and Treatment of PIK3CA-Related Overgrowth Spectrum

ABSTRACT

Hyperactivation of the PI3K/AKT/mTOR signaling pathway caused by PIK3CA mutations is associated with a category of overgrowth syndromes that are defined as PIK3CA -related overgrowth spectrum (PROS). The clinical features of PROS are highly heterogeneous and usually present as vascular malformations, bone and soft tissue overgrowth, and neurological and visceral abnormalities. Detection of PIK3CA variants is necessary for diagnosis and provides the basis for targeted therapy for PROS. Drugs that inhibit the PI3K pathway offer alternatives to conventional therapies. This article reviews the current knowledge of PROS and summarizes the latest progress in precise treatment, providing new insights into future therapies and research goals.

The potential mechanism of Fructus Ligustri Lucidi promoting osteogenetic differentiation of bone marrow mesenchymal stem cells based on network pharmacology, molecular docking and experimental identification

Recent studies have shown that the differentiation of bone marrow mesenchymal stem cells (BMSCs) into osteogenic lineages can promotes bone formation and maintains bone homeostasis, which has become a promising therapeutic strategy for skeletal diseases such as osteoporosis. Fructus Ligustri Lucidi (FLL) has been widely used for the treatment of osteoporosis and other orthopedic diseases for thousands of years. However, whether FLL plays an anti-osteoporosis role in promoting the osteogenic differentiation of BMSCs, as well as its active components, targets, and specific molecular mechanisms, has not been fully elucidated. First, we obtained 13 active ingredients of FLL from the Traditional Chinese Medicine Systems Pharmacology (TCSMP) database, and four active ingredients without any target were excluded. Subsequently, 102 common drug-disease targets were subjected to protein-protein interaction (PPI) analysis, Gene Oncology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. The results of the three analyses were highly consistent, indicating that FLL promoted the osteogenic differentiation of BMSCs by activating the PI3K/AKT signaling pathway. Finally, we validated previous predictions using in vitro experiments, such as alkaline phosphatase (ALP) staining, alizarin red staining (ARS), and western blot analysis of osteogenic-related proteins. The organic combination of network pharmacological predictions with in vitro experimental validation comprehensively confirmed the reliability of FLL in promoting osteogenic differentiation of BMSCs. This study provides a strong theoretical support for the specific molecular mechanism and clinical application of FLL in the treatment of bone formation deficiency.

Kaempferol promotes the osteogenesis in rBMSCs via mediation of SOX2/miR-124-3p/PI3K/Akt/mTOR axis

BACKGROUND

It is reported that the osteogenesis in bone marrow mesenchymal stem cells (BMSCs) can alleviate osteoporosis progression. It has been found that Kae can promote the osteogenesis in BMSCs. However, the mechanism by which Kae mediates the osteogenesis in BMSCs is largely unknown.

METHODS

RBMSCs were collected from rats. The cytotoxicity of Kae was detected by CCK-8 assay. The osteogenic calcification in rBMSCs was measured by alizarin red staining, and ALP staining was performed to test the ALP activity in osteoblasts. The binding relationship between SOX2 and miR-124-3p was explored by dual luciferase report assay and Chromatin Immunoprecipitation (ChIP). RT-qPCR and western blot were performed to assess mRNA and protein levels, respectively.

RESULTS

Kae (10 μM) significantly increased the calcification, ALP activity, SOX2 level, activated PI3K/Akt/mTOR signaling and inhibited miR-124-3p level in rBMSCs, while knockdown of SOX2 reversed this phenomenon. Meanwhile, SOX2 suppressed the transcription of miR-124-3p, and SOX2 promoted the osteogenic differentiation in rBMSCs via regulation of miR-124-3p. MiR-124-3p could inactivate PI3K/Akt/mTOR to inhibit the osteogenic differentiation.

CONCLUSION

Kae significantly promoted the osteogenesis in rBMSCs via mediation of SOX2/miR-124-3p/PI3K/Akt/mTOR axis. Thus, our study might shed new lights in exploring new methods against osteoporosis.

Analysis of the cells isolated from epithelial cell rests of Malassez through single-cell limiting dilution

The epithelial cell rests of Malassez (ERM) are essential in preventing ankylosis between the alveolar bone and the tooth (dentoalveolar ankylosis). Despite extensive research, the mechanism by which ERM cells suppress ankylosis remains uncertain; perhaps its varied population is to reason. Therefore, in this study, eighteen unique clones of ERM (CRUDE) were isolated using the single-cell limiting dilution and designated as ERM 1-18. qRT-PCR, ELISA, and western blot analyses revealed that ERM-2 and -3 had the highest and lowest amelogenin expression, respectively. Mineralization of human periodontal ligament fibroblasts (HPDLF) was reduced in vitro co-culture with CRUDE ERM, ERM-2, and -3 cells, but recovered when an anti-amelogenin antibody was introduced. Transplanted rat molars grown in ERM-2 cell supernatants produced substantially less bone than those cultured in other cell supernatants; inhibition was rescued when an anti-amelogenin antibody was added to the supernatants. Anti-Osterix antibody staining was used to confirm the development of new bones. In addition, next-generation sequencing (NGS) data were analysed to discover genes related to the distinct roles of CRUDE ERM, ERM-2, and ERM-3. According to this study, amelogenin produced by ERM cells helps to prevent dentoalveolar ankylosis and maintain periodontal ligament (PDL) space, depending on their clonal diversity.

DLX Genes: Roles in Development and Cancer

Simple Summary

DLX homeobox family genes encode transcription factors that have indispensable roles in embryonic and postnatal development. These genes are critically linked to the morphogenesis of craniofacial structures, branchial arches, forebrain, and sensory organs. DLX genes are also involved in postnatal homeostasis, particularly hematopoiesis and, when dysregulated, oncogenesis. DLX1/2, DLX3/4, and DLX5/6 exist as bigenes on different chromosomes, sharing intergenic enhancers between gene pairs, which allows orchestrated spatiotemporal expression. Genomic alterations of human DLX gene enhancers or coding sequences result in congenital disorders such as split-hand/foot malformation. Aberrant postnatal expression of DLX genes is associated with hematological malignancies, including leukemias and lymphomas. In several mouse models of T-cell lymphoma, Dlx5 has been shown to act as an oncogene by cooperating with activated Akt, Notch1/3, and/or Wnt to drive tumor formation. In humans, DLX5 is aberrantly expressed in lung and ovarian carcinomas and holds promise as a therapeutic target.

Abstract

Homeobox genes control body patterning and cell-fate decisions during development. The homeobox genes consist of many families, only some of which have been investigated regarding a possible role in tumorigenesis. Dysregulation of HOX family genes have been widely implicated in cancer etiology. DLX homeobox genes, which belong to the NK-like family, exert dual roles in development and cancer. The DLX genes are the key transcription factors involved in regulating the development of craniofacial structures in vertebrates. The three DLX bigenes have overlapping expression in the branchial arches. Disruption of DLX function has destructive consequences in organogenesis and is associated with certain congenital disorders in humans. The role of DLX genes in oncogenesis is only beginning to emerge. DLX2 diminishes cellular senescence by regulating p53 function, whereas DLX4 has been associated with metastasis in breast cancer. In human ovarian cancer cells, DLX5 is essential for regulating AKT signaling, thereby promoting cell proliferation and survival. We previously implicated Dlx5 as an oncogene in murine T-cell lymphoma driven by a constitutively active form of Akt2. In this mouse model, overexpression of Dlx5 was caused by a chromosomal rearrangement that juxtaposed the Tcr-beta promoter region near the Dlx5 locus. Moreover, transgenic mice overexpressing Dlx5, specifically in immature T-cells, develop spontaneous thymic lymphomas. Oncogenesis in this mouse model involves binding of Dlx5 to the Notch1 and Notch3 gene loci to activate their transcription. Dlx5 also cooperates with Akt signaling to accelerate lymphomagenesis by activating Wnt signaling. We also discuss the fact that human DLX5 is aberrantly expressed in several human malignancies.