The histone H3K9 methyltransferase G9a regulates tendon formation during development.

G9a is a histone methyltransferase that catalyzes the methylation of histone 3 lysine 9 (H3K9), which is involved in the regulation of gene expression. We had previously reported that G9a is expressed in developing tendons in vivo and in vitro and that G9a-deficient tenocytes show impaired proliferation and differentiation in vitro. In this study, we investigated the functions of G9a in tendon development in vivo by using G9a conditional knockout (G9a cKO) mice.

The G9a histone methyltransferase represses osteoclastogenesis and bone resorption by regulating NFATc1 function.

Epigenetic modifications affect cell differentiation via transcriptional regulation. G9a/EHMT2 is an important epigenetic modifier that catalyzes the methylation of histone 3 lysine 9 (H3K9) and interacts with various nuclear proteins. In this study, we investigated the role of G9a in osteoclast differentiation.

Epigenetic modifier G9a is involved in regulation of mouse tongue development.

Objectives: The tongue comprises multiple tissues of different embryonic origins, including pharyngeal arch, somite, and cranial neural crest (CNC). However, its developmental regulatory mechanisms, especially those involving epigenetic modifiers, remain poorly understood. This study examined the roles of the epigenetic modifier G9a in murine tongue development.

Osteolytic Bone Loss and Skeletal Deformities in a Mouse Model for Early-Onset Paget's Disease of Bone with Mutation Are Treatable by Alendronate.

A novel osteolytic disorder due to mutation was discovered recently as early-onset Paget's disease of bone (PDB). Bone loss and pain in adult PDB patients have been treated using bisphosphonates. However, therapeutic strategies for this specific disorder have not been established.

Tooth transplantation and replantation: Biological insights towards therapeutic improvements.

Transplantation and replantation of teeth are effective therapeutic approaches for tooth repositioning and avulsion, respectively. Transplantation involves transplanting an extracted tooth from the original site into another site, regenerating tissue including the periodontal ligament (PDL) and alveolar bone, around the transplanted tooth. Replantation places the avulsed tooth back to its original site, regenerating functional periodontal tissue.

Profilin-1 negatively controls osteoclast migration by suppressing the protrusive structures based on branched actin filaments.

Background: Profilin-1 (Pfn1), an evolutionarily conserved actin-binding protein, is an important regulator of the cytoskeleton. We previously reported the osteoclast-specific Pfn1-conditional knockout (cKO) mice had postnatal osteolytic phenotype with craniofacial and long-bone deformities associated with increased migration of cultured osteoclasts. We hypothesized the increased cellular processes structured with branched actin filaments may underlies the mechanism of increased bone resorption in these mutant mice.

Platelet-derived growth factor-BB regenerates functional periodontal ligament in the tooth replantation.

Tooth ankylosis is a pathological condition of periodontal ligament (PDL) restoration after tooth replantation. Platelet-derived growth factor-BB (PDGF-BB) has been proposed as a promising factor for preventing tooth ankylosis. Using rat tooth replantation model, we investigated whether PDGF-BB accelerates the repair of PDL after tooth replantation without ankylosis, and its molecular mechanisms.

G9a is involved in the regulation of cranial bone formation through activation of Runx2 function during development.

The methyltransferase G9a was originally isolated as a histone methyltransferase that catalyzes the methylation of histone 3 lysine 9 (H3K9) to a dimethylated state (H3K9me2). Recent studies have revealed that G9a has multiple functions in various cells, including osteoblasts. Here, we investigated G9a function during cranial bone formation.

Annexin A5 Involvement in Bone Overgrowth at the Enthesis.

Little is known about the molecular mechanisms of enthesis formation in mature animals. Here, we report that annexin A5 (Anxa5) plays a critical role in the regulation of bone ridge outgrowth at the entheses. We found that Anxa5 is highly expressed in the entheses of postnatal and adult mice.

Possible association of oestrogen and Cryba4 with masticatory muscle tendon-aponeurosis hyperplasia.

Objective: Masticatory muscle tendon-aponeurosis hyperplasia, which is associated with limited mouth opening, progresses very slowly from adolescence. The prevalence rates of this disease are higher among women than among men, suggesting oestrogen involvement. As parafunctional habits are frequently observed, mechanical stress is likely involved in the pathogenesis and advancement of this disease.

Essential roles of G9a in cell proliferation and differentiation during tooth development.

Teeth develop through interactions between epithelial and mesenchymal tissues mediated by a signaling network comprised of growth factors and transcription factors. However, little is known about how epigenetic modifiers affect signaling pathways and thereby regulate tooth formation. We previously reported that the histone 3 lysine 9 (H3K9) methyltransferase (MTase) G9a is specifically enriched in the tooth mesenchyme during mouse development.

Histone deacetylase inhibition enhances in-vivo bone regeneration induced by human periodontal ligament cells.

Unlabelled: Periodontal ligament cells have the potential to differentiate into bone forming osteoblasts and thus represent a good cellular candidate for bone regeneration. This study aimed to investigate the effect of inhibition of histone deacetylases, using the inhibitor Trichostatin A (TSA), on bone regeneration by human periodontal ligament cells (hPDLCs) in a mouse calvaria bone defect.

Methods: RUNX2 protein and its acetylation was analyzed by immunoprecipitation and western blotting.

Bardet-Biedl syndrome 3 regulates the development of cranial base midline structures.

Bardet-Biedl Syndrome (BBS) is an autosomal recessive disorder and is classified as one of the ciliopathy. The patients manifest a characteristic craniofacial dysmorphology but the effects of Bbs3 deficiency in the developmental process during the craniofacial pathogenesis are still incompletely understood. Here, we analyzed a cranial development of a BBS model Bbs3 mouse.

Cationized gelatin hydrogels mixed with plasmid DNA induce stronger and more sustained gene expression than atelocollagen at calvarial bone defects in vivo.

Gene transduction of exogenous factors at local sites in vivo is a promising approach to promote regeneration of tissue defects owing to its simplicity and capacity for expression of a variety of genes. Gene transduction by viral vectors is highly efficient; however, there are safety concerns associated with viruses. As a method for nonviral gene transduction, plasmid DNA delivery is safer and simpler, but requires an efficient carrier substance.

BMP-2 Enhances Lgr4 Gene Expression in Osteoblastic Cells.

Osteoporosis is one of the most prevalent diseases and the number of patients suffering from this disease is soaring due to the increase in the aged population in the world. The severity of bone loss in osteoporosis is based on the levels of impairment in the balance between bone formation and bone resorption, two arms of the bone metabolism, and bone remodeling. However, determination of bone formation levels is under many layers of control that are as yet fully defined.

H3K9MTase G9a is essential for the differentiation and growth of tenocytes in vitro.

Cell differentiation is controlled by specific transcription factors. The functions and expression levels of these transcription factors are regulated by epigenetic modifications, such as histone modifications and cytosine methylation of the genome. In tendon tissue, tendon-specific transcription factors have been shown to play functional roles in the regulation of tenocyte differentiation.

Coordinated expression of H3K9 histone methyltransferases during tooth development in mice.

Tissue-specific gene expression is subjected to epigenetic and genetic regulation. Posttranslational modifications of histone tails alter the accessibility of nuclear proteins to DNA, thus affecting the activity of the regulatory complex of nuclear proteins. Methylation at histone 3 lysine 9 (H3K9) is a crucial modification that affects gene expression and cell differentiation.

Efficient expansion of mouse primary tenocytes using a novel collagen gel culture method.

Development of regenerative therapies for damaged tendons remains a great challenge, largely because of lack of information regarding the mechanisms responsible for differentiation of tenocytes. Mouse tenocytes have not been fully characterized owing to the absence of efficient and reproducible methods for their in vitro expansion without losing phenotypic features. The objective of the study was to establish an improved and reliable method for stable primary culture of mouse tenocytes by using collagen gel.

Alendronate promotes bone formation by inhibiting protein prenylation in osteoblasts in rat tooth replantation model.

Bisphosphonates (BPs) are a major class of antiresorptive drug, and their molecular mechanisms of antiresorptive action have been extensively studied. Recent studies have suggested that BPs target bone-forming cells as well as bone-resorbing cells. We previously demonstrated that local application of a nitrogen-containing BP (N-BP), alendronate (ALN), for a short period of time increased bone tissue in a rat tooth replantation model.

Predominant expression of H3K9 methyltransferases in prehypertrophic and hypertrophic chondrocytes during mouse growth plate cartilage development.

Histone lysine methylation (HKM) is an epigenetic change that establishes cell-specific gene expression and determines cell fates. In this study, we investigated the expression patterns of histone H3 lysine 9 methyltransferases (H3K9MTases) G9a (euchromatic histone lysine N-methyltransferase 2, Ehmt2), GLP (euchromatic histone lysine N-methyltransferase 1, Ehmt1), SETDB1 (SET domain, bifurcated 1), PRDM2 (PR domain containing 2), SUV39H1 (suppressor of variegation 3-9 homolog 1), and SUV39H2, as well as the distribution of 3 types of HKM at histone H3 lysine 9: mono- (H3K9me1), di- (H3K9me2), or tri-methylation (H3K9me3), during mouse growth plate development. In the forelimb cartilage primordial at embryonic day 12.

Negligible immunogenicity of terminally differentiated cells derived from induced pluripotent or embryonic stem cells.

The advantages of using induced pluripotent stem cells (iPSCs) instead of embryonic stem (ES) cells in regenerative medicine centre around circumventing concerns about the ethics of using ES cells and the likelihood of immune rejection of ES-cell-derived tissues. However, partial reprogramming and genetic instabilities in iPSCs could elicit immune responses in transplant recipients even when iPSC-derived differentiated cells are transplanted. iPSCs are first differentiated into specific types of cells in vitro for subsequent transplantation.

Improved methods for detection of β-galactosidase (lacZ) activity in hard tissue.

The β-galactosidase gene (lacZ) of Escherichia coli is widely used as a reporter gene. The expression of lacZ can be detected by enzyme-based histochemical staining using chromogenic substrates such as 5-bromo-4-chloro-3-indolyl-β-D: -galactoside (X-gal). Because the enzymatic activity of lacZ is vulnerable to high temperatures and acid treatment for demineralization, detection of lacZ on paraffinized sections is difficult, especially for hard tissues, which require demineralization before sectioning in paraffin.

Osteopontin Deficiency Suppresses Tumor Necrosis Factor-α-Induced Apoptosis in Chondrocytes.

Objective: Apoptosis of chondrocytes in articular cartilage has been observed in rheumatoid arthritis patients. However, molecules involved in such chondrocyte apoptosis in arthritic joints have not been fully understood. We previously observed that apoptosis of chondrocytes is enhanced in a murine arthritis model induced by injection with anti-type II collagen antibodies and lipopolysaccharide (mAbs/LPS), and osteopontin (OPN) deficiency suppresses chondrocyte apoptosis in this arthritis model in vivo.