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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. To elucidate the pathological condition, we examined the effect of oestrogen on tenocyte function and the relationship between mechanical stress and crystallin beta A4 (Cryba4), using murine TT‐D6 tenocytes. Materials and Methods: Cell proliferation assays, RT‐PCR, real‐time RT‐PCR, Western blot analysis and mechanical loading experiments were performed. Results: The physiological dose of oestrogen increased the levels of scleraxis and tenomodulin in TT‐D6 tenocytes. In contrast, forced expression of Cryba4 inhibited scleraxis expression in these cells. Surprisingly, oestrogen significantly promoted cell differentiation in the Cryba4‐overexpressing TT‐D6 tenocytes. Moreover, tensile force induced Cryba4 expression in these tendon cells. Conclusion: Oestrogen and Cryba4 may be associated with the progression of masticatory muscle tendon‐aponeurosis hyperplasia. [ABSTRACT FROM AUTHOR]

A new concept of IgG4-related disease characterized by a high serum IgG4 level and tissue infiltration of IgG4-positive plasmacytes that can involve salivary glands has been proposed. In this article, 2 patients with IgG4-related sclerosing sialadenitis involving the submandibular glands are reported. One patient presented with bilateral and painless swelling of the submandibular glands. He had already been treated with systemic prednisolone owing to the occurrence of retrobulbar neuritis. Laboratory examinations showed high serum IgG4 concentrations, and a biopsy of the submandibular gland revealed the infiltration of IgG4-positive plasmacytes. Abdominal computerized tomography demonstrated tumefaction in the tail of the pancreas, thus suggesting localized autoimmune pancreatitis. The other patient also showed bilateral and painless swelling of the submandibular glands, but there was no involvement of any other organs. These patients were effectively treated with corticosteroids, which resulted in a reduction of the swelling of the submandibular gland and increased saliva. When a patient is suspected of having sclerosing sialadenitis, it is important to consider that the patient may have a systemic IgG4-related plasmacytic disease. [ABSTRACT FROM AUTHOR]

Bone morphogenetic protein 3b (BMP3b), also known as growth differentiation factor 10 (GDF10), is a non-osteogenic BMP highly expressed in the skeleton. Although in vitro studies have shown that BMP3b suppresses osteoblast differentiation, the physiological role of BMP3b in regulating bone mass in vivo remains unknown. Here, we show that BMP3b deletion in mice leads to a high bone mass phenotype via an unexpected novel mechanism involving de-repression of canonical BMP/Smad signaling. BMP3b null mice were viable, and exhibited no significant difference in body size compared to wildtype control. Trabecular bone parameters assessed by histomorphometry and μCT, revealed a significant increase in bone volume and bone mineral density. Expression of osteoblast-differentiation genes were elevated in bone tissue of BMP3b null mice, whereas expression of osteoclast-related genes remained unchanged. Consistent with this, Bmp3b was highly expressed in osteoblasts relative to osteoclast cells. Ex-vivo culture of primary bone marrow mesenchymal stem cells (BMSCs) and primary bone marrow-derived osteoclasts revealed that inactivation of BMP3b enhances osteogenesis without affecting osteoclastogenesis. Mechanistically, we found that BMP3b suppressed BMP4-induced Smad1/5 phosphorylation and inhibited the activity of a BMP4-driven Id-1 luciferase reporter. Protein-protein interaction assays revealed that BMP3b competitively interfered with the association of BMP4 and BMP type I receptors. These findings suggest that BMP3b regulates bone mass by acting as a BMP receptor antagonist. Thus, maintenance of bone mass involves antagonism of canonical BMP/Smad signaling by a member of the BMP family., Competing Interests: Declaration of competing interest The authors declare that this article and related all data are original, is not under consideration by any other journals. The authors also declare that we will not submit this manuscript to any other journals during the review period of Bone. The authors also confirm that data from previously published papers have not been used in this manuscript and agree to provide information about any relevant publications., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Bone morphogenetic protein (BMP)-3b, also known as growth differentiation factor (GDF)-10, belongs to the transforming growth factor (TGF)-β superfamily. Despite being named a BMP, BMP3b is considered as an intermediate between the TGFβ/activin/myostatin and BMP/GDF subgroups of the TGFβ superfamily. Myoblast differentiation is tightly regulated by various cytokines, including the TGFβ superfamily members. However, despite BMP3b supporting the maintenance of skeletal myofibers, myoblast differentiation induced by BMP3b remains unclear. In this study, BMP3 expression levels in isolated satellites were very low compared to those in the skeletal muscle tissues. We analyzed cardiotoxin-induced muscle regeneration. Intact muscle fiber size was larger in BMP3b null mice than in wild-type mice; however, regenerated muscle fiber size did not differ between the null and wild-type mice. Next, we analyzed the satellite cell-specific BMP3b-overexpressing (BMP3b Tg) mice. Intact fiber size was increased in BMP3b Tg mice. However, regenerating tibialis anterior muscle size was reduced in BMP3b Tg mice compared to that in control mice. BMP3b overexpression in C2C12 cells stimulated Smad2/3 signaling. Moreover, BMP3b overexpression and conditioned medium of BMP3b-expressing Chinese hamster ovary cells strongly suppressed myoblast differentiation by repressing transactivation. Overall, our data suggest that BMP3b is not necessary for muscle regeneration; however, excessive BMP3b interferes with muscle regeneration by suppressing myoblast differentiation., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2024. Published by Elsevier Inc.)

The micronutrient vitamin C is essential for the maintenance of skeletal muscle health and homeostasis. The pro-myogenic effects of vitamin C have long been attributed to its role as a general antioxidant agent, as well as its role in collagen matrix synthesis and carnitine biosynthesis. Here, we show that vitamin C also functions as an epigenetic compound, facilitating chromatin landscape transitions during myogenesis through its activity as an enzymatic cofactor for histone H3 and DNA demethylation. Utilizing C2C12 myoblast cells to investigate the epigenetic effects of vitamin C on myogenesis, we observe that treatment of cells with vitamin C decreases global H3K9 methylation and increases 5-hmC levels. Furthermore, vitamin C treatment enhances myoblast marker gene expression and myotube formation during differentiation. We identify KDM7A as a histone lysine demethylase markedly upregulated during myogenesis. Accordingly, knockdown of Kdm7a prevents the pro-myogenic effects of vitamin C. Chromatin immunoprecipitation analysis showed that KDM7A occupies the promoter region of the myogenic transcription factor MyoD1 where it facilitates histone demethylation. We also confirm that the methylcytosine dioxygenases TET1 and TET2 are required for myogenic differentiation and that their loss blunts stimulation of myogenesis by vitamin C. In conclusion, our data suggest that an epigenetic mode of action plays a major role in the myogenic effects of vitamin C., (© 2024 Wiley Periodicals LLC.)

Point mutations in KIF22 have been linked to spondyloepimetaphyseal dysplasia with joint laxity, type 2 (SEMDJL2). Skeletal features of SEMDJL2 include short stature and joint laxity. Mechanisms underlying these limb abnormalities are unknown. Here in this manuscript, we have investigated the function of KIF22 in chondrocytes. Quantitative PCR and immunostaining revealed that Kif22 was highly expressed in proliferating-zone growth-plate chondrocytes. Kif22 knockdown resulted in defective mitotic spindle formation and reduced cell proliferation. Forced expression of SEMDJL-associated mutant Kif22 constructs likewise induced abnormal mitotic spindle morphology and reduced proliferation. Mice expressing a KIF22 truncation mutant had shorter growth plates and shorter tibial bones compared to wild-type mice. These results suggest that KIF22 regulates mitotic spindle formation in proliferating chondrocytes thereby linking the stunted longitudinal bone growth observed in SEMDJL2 to failures of chondrocyte division., Competing Interests: The authors declare no competing interests., (© 2024 The Author(s).)

Purpose/aim of Study: During the development of the vertebrate skeleton, the progressive differentiation and maturation of chondrocytes from mesenchymal progenitors is precisely coordinated by multiple secreted factors and signaling pathways. The WNT signaling pathway has been demonstrated to play a major role in chondrogenesis. However, the identification of secreted factors that fine-tune WNT activity has remained elusive. Here, in this study, we have identified PI15 (peptidase inhibitor 15, protease Inhibitor 15, SugarCrisp), a member of the CAP (cysteine rich secretory proteins, antigen 5, and pathogenesis related 1 proteins) protein superfamily, as a novel secreted WNT antagonist dynamically upregulated during chondrocyte differentiation., Materials and Methods: ATDC5 cells, C3H10T1/2 micromass cultures and primary chondrocyte cells were used as in vitro models of chondrogenesis. PI15 levels were stably depleted or overexpressed by viral shRNA or expression vectors. Chondrogenesis was evaluated by qPCR gene expression analysis and Alcian blue staining. Protein interactions were determined by coimmunoprecipitation assays., Results and Conclusions: shRNA-mediated knockdown of PI15 in ATDC5 cells, C3H10T1/2 cells or primary chondrocytes inhibits chondrogenesis, whereas the overexpression of PI15 strongly enhances chondrogenic potential. Mechanistically, PI15 binds to the LRP6 WNT co-receptor and blocks WNT-induced LRP6 phosphorylation, thus repressing WNT-induced transcriptional activity and alleviating the inhibitory effect of WNT signaling on chondrogenesis. Altogether, our findings suggest that PI15 acts as a key regulator of chondrogenesis and unveils a mechanism through which chondrocyte-derived molecules can modulate WNT activity as differentiation proceeds, thereby creating a positive feedback loop that further drives differentiation.

Royal jelly (RJ) is recognized as beneficial to mammalian health. Multilineage differentiation potential is an important property of mesenchymal stem cells (MSCs). C2C12 cells have an innate ability to differentiate into myogenic cells. Like MSCs, C2C12 cells can also differentiate into osteoblast- and adipocyte-lineage cells. We recently reported that RJ enhances the myogenic differentiation of C2C12 cells. However, the effect of RJ on osteoblast or adipocyte differentiation is still unknown. Here in this study, we have examined the effect of RJ on the osteoblast and adipocyte differentiation of C2C12 cells. Protease-treated RJ was used to reduce the adverse effects caused by RJ supplementation. To induce osteoblast or adipocyte differentiation, cells were treated with bone morphogenetic proteins (BMP) or peroxisome proliferator-activated receptor γ (PPARγ) agonist, respectively. RNA-seq was used to analyze the effect of RJ on gene expression. We found that RJ stimulates osteoblast and adipocyte differentiation. RJ regulated 279 genes. RJ treatment upregulated glutathione-related genes. Glutathione, the most abundant antioxidative factor in cells, has been shown to promote osteoblast differentiation in MSC and MSC-like cells. Therefore, RJ may promote osteogenesis, at least in part, through the antioxidant effects of glutathione. RJ enhances the differentiation ability of C2C12 cells into multiple lineages, including myoblasts, osteoblasts, and adipocytes.

Despite significant advances in the management of patients with oral cancer, maxillofacial reconstruction after ablative surgery remains a clinical challenge. In bone tissue engineering, biofabrication strategies have been proposed as promising alternatives to solve issues associated with current therapies and to produce bone substitutes that mimic both the structure and function of native bone. Among them, laser-assisted bioprinting (LAB) has emerged as a relevant biofabrication method to print living cells and biomaterials with micrometric resolution onto a receiving substrate, also called 'biopaper'. Recent studies have demonstrated the benefits of prevascularization using LAB to promote vascularization and bone regeneration, but mechanical and biological optimization of the biopaper are needed. The aim of this study was to apply gelatin-sheet fabrication process to the development of a novel biopaper able to support prevascularization organized by LAB for bone tissue engineering applications. Gelatin-based sheets incorporating bioactive glasses (BGs) were produced using various freezing methods and crosslinking (CL) parameters. The different formulations were characterized in terms of microstructural, physical, mechanical, and biological properties in monoculture and coculture. Based on multi-criteria analysis, a rank scoring method was used to identify the most relevant formulations. The selected biopaper underwent additional characterization regarding its ability to support mineralization and vasculogenesis, its bioactivity potential and in vivo degradability. The biopaper 'Gel5wt% BG1wt%-slow freezing-CL160 °C 24 h' was selected as the best candidate, due to its suitable properties including high porosity (91.69 ± 1.55%), swelling ratio (91.61 ± 0.60%), Young modulus (3.97 × 10 4 ± 0.97 × 10 4 Pa) but also its great cytocompatibility, osteogenesis and bioactivity properties. The preorganization of human umbilical vein endothelial cell using LAB onto this new biopaper led to the formation of microvascular networks. This biopaper was also shown to be compatible with 3D-molding and 3D-stacking strategies. This work allowed the development of a novel biopaper adapted to LAB with great potential for vascularized bone biofabrication., (© 2024 IOP Publishing Ltd.)

The world's population is aging. Pneumonia is the leading cause of death among the older adults, with aspiration pneumonia being particularly common. Aspiration pneumonia is caused by a decline in swallowing function. Causes can include age-related sarcopenia of swallowing muscles, cognitive decline, cerebrovascular and other diseases or even changes in individual taste preference. Currently, the main treatment approach for dysphagia is resistance training of swallowing-related muscles. This approach has not been effective and establishment of novel methods are required. In this review, we introduce and discuss the relationship between taste, taste preference, carbonation and swallowing function. Taste and preference improve swallowing function. Recently, it has been shown that a carbonated beverage that combines the functionality of a thickening agent, the appeal of taste, and the stimulation of carbonation improves swallowing function. This may be very useful in the recovery of swallowing function. It is important to note that deliciousness is based not only on taste and preference, but also on visual information such as food form. Umami taste receptors are expressed not only in taste buds but also in skeletal muscle and small intestine. These receptors may be involved in homeostasis of the amino acid metabolic network, i.e., the process of amino acid ingestion, intestine absorption, and storage in skeletal muscle. Proper stimulation of umami receptors in organs other than taste buds may help maintain nutritional status and muscle mass. Umami receptors are therefore a potential therapeutic target for dysphagia., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Okubo, Morishita, Odani, Sakaguchi, Kikutani and Kokabu.)

Ideal regeneration of hard tissue and dental pulp has been reported with the use of a combination of bioactive glass and basic fibroblast growth factor (bFGF). However, no previous study has investigated the molecular mechanisms underlying the processes induced by this combination in dental pulp cells. This study aimed to examine the cellular phenotype and transcriptional changes induced by the combination of bioactive glass solution (BG) and bFGF in dental pulp cells using phase-contrast microscopy, a cell counting kit-8 assay, alkaline phosphatase staining, and RNA sequence analysis. bFGF induced elongation of the cell process and increased the number of cells. Whereas BG did not increase ALP activity, it induced extracellular matrix-related genes in the dental pulp. In addition, the combination of BG and bFGF induces gliogenesis-related genes in the nervous system. This is to say, bFGF increased the viability of dental pulp cells, bioactive glass induced odontogenesis, and a dual stimulation with bioactive glass and bFGF induced the wound healing of the nerve system in the dental pulp. Taken together, bioactive glass and bFGF may be useful for the regeneration of the dentin-pulp complex.

In many cases, enteral tube feeding is begun after stroke without adequate assessment of feeding ability, swallowing function, and nutritional status. A 72-year-old man was recovering at home after a stroke and consulted us because he wanted to resume taking food by mouth. He had tube feeding for 13 months after the stroke. We offered him feeding and swallowing training and proper nutrition guidance by visiting dental staff and managerial dietitians at home and concluded the patient was sufficiently able to take oral food. After 4 months, the patient was completely weaned from tube feeding., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Severe intraoral pain induces difficulty in eating and speaking, leading to a decline in the quality of life. However, the molecular mechanisms underlying intraoral pain remain unclear. Here, we investigated gene modulation in the trigeminal ganglion and intraoral pain-related behavior in a rat model of acetic acid-induced oral ulcerative mucositis. Oral ulceration was observed on day 2 after acetic acid treatment to the oral mucosa of male Wistar rats, causing spontaneous pain and mechanical allodynia. Deoxyribonucleic acid microarray analysis of trigeminal ganglion tissue indicated that Hamp (a hepcidin gene that regulates cellular iron transport) was the most upregulated gene. In the oral ulcerative mucositis model, the upregulation of Hamp was also induced in the ulcer region but not in the liver, with no increase in hepcidin levels in the plasma and saliva, indicating that hepcidin was produced locally in the ulcer region in the model. Systemic antibiotic pretreatment did not increase the mRNA levels of Hamp in the trigeminal ganglion and ulcer regions. Hepcidin injection into the oral mucosa enhanced neuronal excitability in response to noxious mechanical stimulation of the oral mucosa in trigeminal spinal subnucleus interpolaris/caudalis neurons. These results imply that oral ulcerative mucositis induces oral mucosal pain because of infectious inflammation of the ulcerative area and potentiates Hamp, which represents anti-bacterial and anti-peptidase gene expression in the ulcer region and trigeminal ganglion. The regulation of cellular iron transport by hepcidin is likely involved in oral ulcerative mucositis-induced pain., Competing Interests: The authors declare that this study was conducted without any commercial or financial relationships construed as potential competing interests (Financial support from Tsumura & Co. was outside the last 5-year time frame). This does not alter our adherence to PLOS ONE policies on sharing data and materials., (Copyright: © 2023 Hitomi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Japan has the world's highest life longevity, and centenarian patients are no longer rare. However, sufficient information related to centenarians is not available. Herein, we report the case of a 101-year-old centenarian woman who recovered from extreme inactivity and general weakness, mainly through nutritional management at home, to understand instances of nutritional management in centenarians. The patient developed lethargy, with a rapid decline in activity levels and food intake. She was diagnosed with senility by a primary doctor. We concluded that she had no problems with feeding and swallowing and predicted that her motivation to eat had decreased. We planned an intervention that lasted three months. To reduce the risk of aspiration, we paid attention to her posture while eating. To stimulate her appetite, we increased the variety and color of food items. To consider both the texture of food and safety, we changed the form of foods from paste (IDDSI Level 4)-like to solid food of regular size as much as possible. We recommended that the patient consume her favorite sweet between meals to enjoy eating. Two and half months after the initial intervention, the patient's inactivity and general weakness improved dramatically, which was recognized by her willingness to eat, laugh loudly, and hum, although she could not speak clearly. The patient finally was able to have dinner with her family.

Taxifolin (dihydroquercetin), which has various pharmacological functions, is contained in edible plants. Some taxifolin-containing foodstuffs such as adzuki bean and sorghum seeds are cooked by themselves and with other starch-containing ingredients. In this study, non-glutinous rice flour (joshin-ko) and potato starch were heated with taxifolin. The heating resulted in the slowdown of pancreatin-induced hydrolysis of suspendable starch in joshin-ko and soluble starch in potato starch. The products of taxifolin formed by the heating such as quercetin were combined with starch during the heating and/or retrogradation, which was converted into the suspendable starch in joshin-ko and the soluble starch in the potato. Taking the difference in protein content and amylose chain length between joshin-ko and potato starch into account, the slowdown is discussed to be due to the binding of the reaction products of taxifolin to proteins in suspendable starch in joshin-ko and to soluble amylose in potato starch.

The NF-κB family of transcription factors plays an important role in skeletal development and bone homeostasis. In osteoblast cells, NF-κB signaling has been shown to suppress survival, proliferation, and differentiation. Furthermore, pharmacological suppression of NF-κB enhances osteoblast differentiation and bone formation. Thus, NF-κB antagonists are promising candidates as anabolic agents for enhancing bone mass. In this study, we describe the mechanism by which nobiletin, an inhibitor of NF-κB activity, regulates osteoblast differentiation and mineralization. We found that in MC3T3-E1 osteoblast cells, nobiletin inhibited a TNF-α responsive NF-κB luciferase reporter and also decreased the induction of classical NF-κB target genes by TNF-α. Consistent with this, nobiletin prevented TNF-α -mediated suppression of osteogenesis and potently enhanced the differentiation and mineralization of MC3T3-E1 cells. Likewise, in an in vivo BMP2-induced ectopic bone formation assay, nobiletin markedly enhanced ossicle bone volume. Western blotting and SMAD-responsive luciferase assays also demonstrated that NF-κB suppression of BMP signaling could be inhibited by nobiletin. Thus, our data suggest that mechanistically, nobiletin prevents the endogenous repression of BMP signaling by TNF-α, thereby enhancing osteoblast activity. In conclusion, nobiletin is a novel NF-κB antagonist that may be a useful anabolic agent for bone formation., (© 2022 The Authors. FASEB BioAdvances published by Wiley Periodicals LLC on behalf of The Federation of American Societies for Experimental Biology.)

Background: Melanoma is a malignant tumor characterized by high proliferation and aggressive metastasis. To address the molecular mechanisms of the proto-oncogene, Rous sarcoma oncogene (Src), which is highly activated and promotes cell proliferation, migration, adhesion, and metastasis in melanoma. Plectin, a cytoskeletal protein, has recently been identified as a Src-binding protein that regulates Src activity in osteoclasts. Plectin is a candidate biomarker of certain tumors because of its high expression and the target of anti-tumor reagents such as ruthenium pyridinecarbothioamide. The molecular mechanisms by which plectin affects melanoma is still unclear. In this study, we examined the role of plectin in melanoma tumor formation., Methods: We used CRISPR/Cas9 gene editing to knock-out plectin in B16 mouse melanoma cells. Protein levels of plectin and Src activity were examined by western blotting analysis. In vivo tumor formation was assessed by subcutaneous injection of B16 cells into nude mice and histological analysis performed after 2 weeks by Hematoxylin-Eosin (H&E) staining. Cell proliferation was evaluated by direct cell count, cell counting kit-8 assays, cyclin D1 mRNA expression and Ki-67 immunostaining. Cell aggregation and adhesion were examined by spheroid formation, dispase-based dissociation assay and cell adhesion assays., Results: In in vivo tumor formation assays, depletion of plectin resulted in low-density tumors with large intercellular spaces. In vitro experiments revealed that plectin-deficient B16 cells exhibit reduced cell proliferation and reduced cell-to-cell adhesion. Since Src activity is reduced in plectin-deficient melanomas, we examined the relationship between plectin and Src signaling. Src overexpression in plectin knockout B16 cells rescued cell proliferation and improved cell-to-cell adhesion and cell to extracellular matrix adhesion., Conclusion: These results suggest that plectin plays critical roles in tumor formation by promoting cell proliferation and cell-to-cell adhesion through Src signaling activity in melanoma cells., (© 2022. The Author(s).)

Osteoclasts, which resorb the bone, and osteoblasts, which form the bone, are the key cells regulating bone homeostasis. Osteoporosis and other metabolic bone diseases occur when osteoclast-mediated bone resorption is increased and bone formation by osteoblasts is decreased. Analyses of tyrosine kinase Src-knockout mice revealed that Src is essential for bone resorption by osteoclasts and suppresses bone formation by osteoblasts. Src-knockout mice exhibit osteopetrosis. Therefore, Src is a potential target for osteoporosis therapy. However, Src is ubiquitously expressed in many tissues and is involved in various biological processes, such as cell proliferation, growth, and migration. Thus, it is challenging to develop effective osteoporosis therapies targeting Src. To solve this problem, it is necessary to understand the molecular mechanism of Src function in the bone. Src expression and catalytic activity are maintained at high levels in osteoclasts. The high activity of Src is essential for the attachment of osteoclasts to the bone matrix and to resorb the bone by regulating actin-related molecules. Src also inhibits the activity of Runx2, a master regulator of osteoblast differentiation, suppressing bone formation in osteoblasts. In this paper, we introduce the molecular mechanisms of Src in osteoclasts and osteoblasts to explore its potential for bone metabolic disease therapy.

Background: Necrotizing periodontitis (NP) is a reactive and destructive inflammatory process that occurs in response to bacterial infection. Predisposing factors such as compromised host immune responses contribute significantly to NP pathogenesis. NP occasionally progresses to a more advanced and life-threatening state., Case Presentation: A 73-year-old man in need of nursing care visited our dental clinic with severe gingival pain and intraoral bleeding. He had a disability and was immunocompromised because his medical history included cerebral infarction and type 2 diabetes mellitus. He was diagnosed with NP based on his typical symptoms, such as prominent bleeding and suppurative discharge from the gingiva, in addition to crater-shaped ulcerations of the interdental papillae. To improve daily oral hygiene, periodontists, dentists, and dental hygienists educated care workers and other staff at the nursing home on appropriate oral cleansing, including brushing three times a day using the Bass technique. Basic periodontal therapy, including whole-mouth scaling and debridement of the root surfaces using hand and ultrasonic instruments, was also performed. After this basic treatment of NP, we extracted the hopeless teeth. Currently, dentists visit the patient fortnightly to manage his oral hygiene. To date, good oral health has been maintained.

MyoD, Myf5, myogenin, and MRF4 (also known as Myf6 or herculin) are myogenic regulatory factors (MRFs). MRFs are regarded as master transcription factors that are upregulated during myogenesis and influence stem cells to differentiate into myogenic lineage cells. In this review, we summarize MRFs, their regulatory factors, such as TLE3, NF-κB, and MRF target genes, including non-myogenic genes such as taste receptors. Understanding the function of MRFs and the physiology or pathology of satellite cells will contribute to the development of cell therapy and drug discovery for muscle-related diseases.

Membranous substances in the pharynx are occasionally observed in tube feeding patients during the fiberoptic endoscopic evaluation of swallowing. Although the mechanism of the formation of these deposits sometimes causes problems, such as dysphagia, asphyxia, or aspiration pneumonia, a 91-year-old male complained about difficulty of swallowing. He had a history of cerebral infarction and aspiration pneumonitis. There was a large amount of oral desquamated epithelium, dental plaque, and calculus in his mouth. Nurses and care workers administered oral care such as rubbing the tongue and buccal mucosa daily. Dentists and oral hygienists visited and provided special oral care three times per week. At least for 77 days, the patient had no recurrence of pneumonitis. The oral desquamated epithelium and membranous substances in the pharynx decreased drastically. 2 months after the first examination, the patient was able to start rehabilitation with food. Some studies have indicated that pharyngeal deposits are derived from the oral mucosa, and through our case, we realized the importance of daily oral care by interprofessional work to reduce membranous substances in the pharynx., Competing Interests: The authors declare that they have no known competing financial interest or personal relationship that could appear to influence the work reported in this paper., (Copyright © 2022 Masahiko Okubo et al.)

DNA methylation is an epigenetic modification critical for the regulation of chromatin structure and gene expression during development and disease. The ten-eleven translocation (TET) enzyme family catalyzes the hydroxymethylation and subsequent demethylation of DNA by oxidizing 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC). Little is known about TET protein function due to a lack of pharmacological tools to manipulate DNA hydroxymethylation levels. In this study, we examined the role of TET-mediated DNA hydroxymethylation during BMP-induced C2C12 osteoblast differentiation using a novel cytosine-based selective TET enzyme inhibitor, Bobcat339 (BC339). Treatment of C2C12 cells with BC339 increased global 5mC and decreased global 5hmC without adversely affecting cell viability, proliferation, or apoptosis. Furthermore, BC339 treatment inhibited osteoblast marker gene expression and decreased alkaline phosphatase activity during differentiation. Methylated DNA immunoprecipitation and bisulfite sequencing showed that inhibition of TET with BC339 led to increased 5mC at specific CpG-rich regions at the promoter of Sp7, a key osteoblast transcription factor. Consistent with promoter 5mC marks being associated with transcriptional repression, luciferase activity of an Sp7-promoter-reporter construct was repressed by in vitro DNA methylation or BC339. Chromatin immunoprecipitation analysis confirmed that TET2 does indeed occupy the promoter region of Sp7. Accordingly, forced overexpression of SP7 rescued the inhibition of osteogenic differentiation by BC339. In conclusion, our data suggest that TET-mediated DNA demethylation of genomic regions, including the Sp7 promoter, plays a role in the initiation of osteoblast differentiation. Furthermore, BC339 is a novel pharmacological tool for the modulation of DNA methylation dynamics for research and therapeutic applications., (© 2022 Federation of American Societies for Experimental Biology.)

Objectives: Myogenic differentiation 1 (Myod1) is involved in the expression of taste receptor type 1 member 1 (Tas1r1) during myogenic differentiation. Further, the target genes of Myod1 participate in transcriptional control, muscle development, and synaptic function. We examined, for the first time, the function of Myod1 in the transcriptional regulation of Tas1r1., Methods: ENCODE chromatin immunoprecipitation and sequencing (ChIP-seq) data of myogenically differentiated C2C12 cells were analyzed to identify the Myod1 and transcription factor 12 (Tcf12) binding sites in the Tas1r1 promoter region. Luciferase reporter assays, DNA affinity precipitation assays, and co-immunoprecipitation assays were also performed to identify the functions of Myod1, Tcf12, and Krüppel-like factor 5 (Klf5)., Results: Based on ENCODE ChIP-seq, Myod1 bound to the Tas1r1 promoter region containing E-boxes 1-3. Luciferase reporter assays revealed that site-directed E-box1 mutations significantly reduced promoter activation induced by Myod1 overexpression. According to the DNA affinity precipitation assay and co-immunoprecipitation assay, Myod1 formed a heterodimer with Tcf12 and bound to E-box1. Further, Klf5 bound to the GT box near E-box1, activating Tas1r1 expression., Conclusions: During myogenic differentiation, the Myod1/Tcf12 heterodimer, in collaboration with Klf5, binds to E-box1 and activates Tas1r1 expression., Competing Interests: Conflict of interest The authors declare no conflicts of interest., (Copyright © 2021 Japanese Association for Oral Biology. Published by Elsevier B.V. All rights reserved.)

TNF-α and NF-κB signaling is involved in the wasting of skeletal muscle in various conditions, in addition to cancer cachexia. TNF-α and NF-κB signaling promotes the expression level of muscle RING finger protein 1, a ubiquitin ligase, causing muscle degradation. Several studies have indicated that of TNF-α and NF-κB signaling suppresses muscle differentiation by reducing the levels of MyoD protein. On the other hand, TNF-α and NF-κB is required for myoblast proliferation. Thus, the role of TNF-α and NF-κB signaling in the process of myogenesis and regeneration of skeletal muscle is not completely elucidated. Here, we reported that TNF-α reduced the width of single fibers of skeletal muscle in an organ culture model. TNF-α and p65 repressed the transactivation of MyoD and suppressed myoblast differentiation. In addition, TNF-α increased the number of satellite cells, and NF-κB signaling was promoted at the proliferation stage during skeletal muscle regeneration in vivo. TNF-α and NF-κB signaling regulate myogenesis to inhibit differentiation and promote proliferation in satellite cells., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2021. Published by Elsevier Inc.)

Periodontal disease is an inflammatory disease caused by periodontopathogenic bacteria, which eventually leads to bone tissue (alveolar bone) destruction as inflammation persists. Periodontal tissues have an immune system against the invasion of these bacteria, however, due to the persistent infection by periodontopathogenic bacteria, the host innate and acquired immunity is impaired, and tissue destruction, including bone tissue destruction, occurs. Osteoclasts are essential for bone destruction. Osteoclast progenitor cells derived from hematopoietic stem cells differentiate into osteoclasts. In addition, bone loss occurs when bone resorption by osteoclasts exceeds bone formation by osteoblasts. In inflammatory bone disease, inflammatory cytokines act on osteoblasts and receptor activator of nuclear factor-κB ligand (RANKL)-producing cells, resulting in osteoclast differentiation and activation. In addition to this mechanism, pathogenic factors of periodontal bacteria and mechanical stress activate osteoclasts and destruct alveolar bone in periodontitis. In this review, we focused on the mechanism of osteoclast activation in periodontitis and provide an overview based on the latest findings., (© 2021 The Authors.)

Myxomas arising in the oral and maxillofacial areas are extremely rare. This study reports a case of myxoma arising in the soft tissue beneath the buccal mucosa of an 86-year-old man., Competing Interests: The authors declare that they have no known competing financial interest or personal relationship that could appear to influence the work reported in this paper., (Copyright © 2021 Masahiko Okubo et al.)

The transcription factor NFATc1 and its binding partner AP-1 (a complex containing c-fos and c-Jun) play a central role in osteoclast differentiation. NFATc1 and AP-1 promote the expression of target genes such as Acp5, Ctsk and also auto-regulate NFATc1 expression as well. We previously reported that protein phosphatase 1 regulatory subunit 18 (PPP1r18) is a negative regulator of osteoclast bone resorption by inhibiting cell attachment to bone matrix. We also reported that PPP1r18 potentially regulates NFATc1 expression during osteoclast differentiation. To further explore this, in this study we have examined the effect of PPP1r18 on NFATc1 expression and activity by overexpressing PPP1r18 during the early stage of osteoclast differentiation. We found that PPP1r18 suppressed NFATc1 expression through inhibition of the transcriptional activity of NFATc1. Since PPP1r18 does not regulate NFATc1 directly, we next explored the involvement of AP-1. Our data showed that c-fos phosphorylation and nuclear localization were reduced by PPP1r18 overexpression. Further experiments showed that overexpression of c-fos together with PPP1r18 rescued NFATc1 expression and transcriptional activity. Moreover, c-fos activity inhibition by PPP1r18 was canceled by mutation of the phosphatase binding site of PPP1r18. Taken together, PPP1r18-regulated phosphatase activity targets c-fos phosphorylation and suppresses subsequent NFATc1 expression and activity., Competing Interests: The authors declare that they have no conflicts of interest., (© 2021 The Author(s).)

The weight of skeletal muscle accounts for approximately 40% of the whole weight in a healthy individual, and the normal metabolism and motor function of the muscle are indispensable for healthy life. In addition, the skeletal muscle of the maxillofacial region plays an important role not only in eating and swallowing, but also in communication, such as facial expressions and conversations. In recent years, skeletal muscle atrophy has received worldwide attention as a serious health problem. However, the mechanism of skeletal muscle atrophy that has been clarified at present is insufficient, and a therapeutic method against skeletal muscle atrophy has not been established. This review provides views on the importance of skeletal muscle in the maxillofacial region and explains the differences between skeletal muscles in the maxillofacial region and other regions. We summarize the findings to change in gene expression in muscle remodeling and emphasize the advantages and disadvantages of denervation-induced skeletal muscle atrophy model. Finally, we discuss the newly discovered beneficial effects of natural compounds on skeletal muscle atrophy.

The ideal retrograde filling material that is easy to handle, has good physicochemical properties, and is biocompatible has not yet been developed. The current study reports the development of a novel bioactive glass based powder for use as a retrograde filling material that is capable of altering the consistency and hardening rate of mixtures when mixed with existing bioactive glass based cement. Furthermore, its physicochemical properties, in vitro effects on human cementoblast-like cells, and in vivo effects on inflammatory responses were evaluated. The surface of the hardened cement showed the formation of hydroxyapatite-like precipitates and calcium and silicate ions were eluted from the cement when the pH level was stabilized at 10.5. Additionally, the cement was found to be insoluble and exhibited favorable handling properties. No adverse effects on viability, proliferation, and expression of differentiated markers were observed in the in vitro experiment, and the cement was capable of inducing calcium deposition in the cells. Moreover, the cement demonstrated a lower number of infiltrated inflammatory cells compared to the other materials used in the in vivo mouse subcutaneous implantation experiment. These findings suggest that the retrograde filling material composed of bioactive glass and the novel bioactive glass based powder exhibits favorable physicochemical properties, cytocompatibility, and biocompatibility.

Glycyrrhiza extract has been used for the treatment of oral and gastric ulcers, but the analgesic mechanism remains unknown. In the present study, we investigated the effects of isoliquiritigenin, an active ingredient of Glycyrrhiza, on Na v channels in vitro and nociceptive behaviors in vivo. In an autopatch-clamp study, isoliquiritigenin inhibited the currents of Na v 1.1, Na v 1.3, Na v 1.6, Na v 1.7, and Na v 1.8 in a channel expression system. In small- and medium-sized cultured trigeminal ganglion neurons, the compound suppressed Na v currents in many neurons (78%) and K v currents in all neurons, dose-dependently. In current-clamp mode, isoliquiritigenin blocked action potential generation in many neurons (64%), but it conversely accelerated action potential generation in the remaining neurons. The opposing effects on action potentials were reproduced in a computational simulation of a modified Hodgkin-Huxley-based model, based on the electrophysiological data. In behavioral experiments, local treatment with isoliquiritigenin suppressed nociceptive behaviors in response to oral ulcer development or nociceptive TRP channel agonists in the oral mucosa and hind paw. These results suggest that isoliquiritigenin exerts an analgesic effect predominantly via inhibitory action on Na v channels on sensory nociceptive fibers. This pharmacological mechanism indicates that isoliquiritigenin is useful for pain relief and provides scientific evidence for Glycyrrhiza at the ingredient level.

Background/aim: An effective bone regenerative method needs to be established for the dental field. To identify a novel osteogenic factor for bone regeneration, we examined the effect of vignacyanidin (VIG) on osteoblastogenesis., Materials and Methods: W20-17 cells, MC3T3-E1 cells, and primary cultured murine calvarial osteoblasts were used. Osteoblast differentiation was stimulated by β-glycerophosphate, ascorbic acid, or bone morphogenetic protein (BMP)-4. Adipogenesis was induced using dexamethasone, 3-isobutyl-1-methylxanthine, insulin, and rosiglitazone. Differentiation or proliferation markers were determined using western blotting and/or the quantitative reverse transcription polymerase chain reaction. Adipogenic cells were visualized by Oil Red O staining., Results: VIG treatment increased the expression of osteoblastic markers and alkaline phosphatase activity of osteoblast-lineage cells in a concentration-dependent manner. However, adipogenesis and cell proliferation were not affected by VIG., Conclusion: VIG treatment promoted osteoblast differentiation in osteoblast-lineage cells., (Copyright© 2021, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Deletion of c-Src, a ubiquitously expressed tyrosine kinase, results in osteoclast dysfunction and osteopetrosis, in which bones harden into "stone." In contrast, deletion of the genes encoding other members of the Src family kinase (SFK) fails to produce an osteopetrotic phenotype. This suggests that c-Src performs a unique function in the osteoclast that cannot be compensated for by other SFKs. We aimed to identify the molecular basis of this unique role in osteoclasts and bone resorption. We found that c-Src, Lyn, and Fyn were the most highly expressed SFKs in WT osteoclasts, whereas Hck, Lck, Blk, and Fgr displayed low levels of expression. Formation of the podosome belt, clusters of unique actin assemblies, was disrupted in src -/- osteoclasts; introduction of constitutively activated SFKs revealed that only c-Src and Fyn could restore this process. To identify the key structural domains responsible, we constructed chimeric Src-Hck and Src-Lyn constructs in which the unique, SH3, SH2, or catalytic domains had been swapped. We found that the Src unique, SH3, and kinase domains were each crucial to establish Src functionality. The SH2 domain could however be substituted with Lyn or Hck SH2 domains. Furthermore, we demonstrate that c-Src's functionality is, in part, derived from an SH3-proximal proline-rich domain interaction with c-Cbl, leading to phosphorylation of c-Cbl Tyr700. These data help clarify Src's unique functionality in the organization of the cytoskeleton in osteoclasts, required for efficient bone resorption and explain why c-Src cannot be replaced, in osteoclasts, by other SFKs., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Honeybees produce royal jelly (RJ) from their cephalic glands. Royal jelly is a source of nutrition for the queen honey bee throughout its lifespan and is also involved in fertility and longevity. Royal jelly has long been considered beneficial to human health. We recently observed that RJ delayed impairment of motor function during aging, affecting muscle fiber size. However, how RJ affects skeletal muscle metabolism and the functional component of RJ is as of yet unidentified. We demonstrate that feeding mice with RJ daily prevents a decrease in myofiber size following denervation without affecting total muscle weight. RJ did not affect atrophy-related genes but stimulated the expression of myogenesis-related genes, including IGF-1 and IGF receptor . Trans-10-hydroxy-2-decenoic acid (10H2DA) and 10-hydroxydecanoic acid (10HDAA), two major fatty acids contained in RJ. After ingestion, 10H2DA and 10HDAA are metabolized into 2-decenedioic acid (2DA) and sebacic acid (SA) respectively. We found that 10H2DA, 10HDAA, 2DA, and SA all regulated myogenesis of C2C12 cells, murine myoblast cells. These novel findings may be useful for potential preventative and therapeutic applications for muscle atrophy disease included in Sarcopenia, an age-related decline in skeletal muscle mass and strength.

Background/aim: Ascorbate peroxidase (APX) derived from Cyanidioschyzon merolae, a primitive red alga living in high temperature and acidic environments, has greater anti-oxidative capacity than similar peroxidases occurring in other plants. In the present study, we examined whether expression of Cyanidioschyzon merolae-derived APX (cAPX) in mammalian cells increases cellular anti-oxidative capacity., Materials and Methods: The cAPX gene was introduced into the mouse fibroblast-like cell line C3H10T1/2. Production of reactive oxygen species (ROS) and/or cell viability was assessed after heat, H 2 O 2 and acid stimulation., Results: Heat and H 2 O 2 stimulation resulted in ROS production. cAPX-expressing cells were more tolerant to oxidative stress induced by heat, H 2 O 2 and acid stimulations than control cells lacking cAPX., Conclusion: Introduction of cAPX increases the anti-oxidative capacity in mammalian cells., (Copyright© 2020, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Background/aim: Geranylgeraniol (GGOH), a C20 isoprenoid naturally occurs in several foods. We previously reported that GGOH treatment reduced the expression levels of Atrogin-1 which is involved in skeletal muscle degradation and stimulates the myogenic differentiation of C2C12 myoblasts. However, the effect of GGOH supplementation on skeletal muscle metabolism in vivo is unknown., Materials and Methods: Skeletal muscle atrophy was induced by denervation. The expression levels of Atrogin-1 were assessed by western blotting or real time PCR., Results: Intraoral administration of GGOH reduced the decrease in the cross-sectional area of muscle fibers and also suppressed the expression levels of Atrogin-1 in denervation induced muscle atrophy. Also, GGOH treatment suppressed the expression of Atrogin-1 and the decrease in skeletal muscle fiber size by glucocorticoid in vitro., Conclusion: Intraoral administration of GGOH rescues denervation-induced muscle atrophy via suppression of Atrogin-1., (Copyright© 2020, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Considering that stress condition associated with osteoporosis, the hypothalamic-pituitary-adrenal (HPA) axis, which is essential for central stress response system, is implicated in regulating bone mass accrual. Melanocortin 2 receptor (MC2R), the receptor of adrenocorticotropic hormone is expressed in both adrenal gland cells and bone cells. To elucidate the role of HPA axis in bone metabolism, we assessed the skeletal phenotype of MC2R deficient mice ( MC2R -/- mice). We first examined bone mineral density and cortical thickness of femur using dual x-ray absorptiometry and micro-computed tomography. We then conducted histomorphometric analysis to calculate the static and dynamic parameters of vertebrae in MC2R -/- mice. The levels of osteoblastic marker genes were examined by quantitative PCR in primary osteoblasts derived from MC2R -/- mice. Based on these observations, bone mineral density of femur in MC2R -/- mice was increasing relative to litter controls. Meanwhile, the thickness of cortical bone of femur in MC2R -/- mice was remarkably elevated. Moreover, serum osteocalcin level was drastically raised in MC2R -/- mice. However, bone histomorphometry revealed that static and dynamic parameters reflecting bone formation and resorption were unchanged in vertebrae of MC2R -/- mice compared to the control, indicating that MC2R function may be specific to appendicular bone than axis bone. Taken together, the HPA axis due to deletion of MC2R is involved in bone metabolism., Competing Interests: The authors declare that there is no conflict of interest., (© 2020 The Authors.)

Bone invasion is a critical factor in determining the prognosis of oral squamous cell carcinoma (OSCC) patients. Transforming growth factor β (TGF-β) is abundantly expressed in the bone matrix and is involved in the acquisition of aggressiveness by tumors. TGF-β is also important to cytoskeletal changes during tumor progression. In this study, we examined the relationship between TGF-β signaling and cytoskeletal changes during bone invasion by OSCC. Immunohistochemical staining of OSCC samples from five patients showed the expression of p130Cas (Crk-associated substrate) in the cytoplasm and phosphorylated Smad3 expression in the nucleus in OSCC cells. TGF-β1 induced the phosphorylation of Smad3 and p130Cas, as well as epithelial-mesenchymal transition (EMT) accompanied by the downregulation of the expression of E-cadherin, a marker of epithelial cells, and the upregulation of the expression of N-cadherin, or Snail, a marker of mesenchymal cells, in human HSC-2 cells and mouse squamous cell carcinome VII (SCCVII) cells. SB431542, a specific inhibitor of Smad2/3 signaling, abrogated the TGF-β1-induced phosphorylation of p130Cas and morphological changes. Silencing p130Cas using an short hairpin RNA (shRNA) or small interfering RNA in SCCVII cells suppressed TGF-β1-induced cell migration, invasion, EMT and matrix metalloproteinase-9 (MMP-9) production. Compared with control SCCVII cells, SCCVII cells with silenced p130Cas strongly suppressed zygomatic and mandibular destruction in vivo by reducing the number of osteoclasts, cell proliferation and MMP-9 production. Taken together, these results showed that the expression of TGF-β/p130Cas might be a new target for the treatment of OSCC bone invasion., (© The Author(s) 2020. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Osteoblasts release adenosine triphosphate (ATP) out of the cell following mechanical stress. Although it is well established that extracellular ATP affects bone metabolism via P2 receptors [such as purinergic receptor P2X7 (P2X7R) and purinergic receptor P2Y2 (P2Y2R)], the mechanism of ATP release from osteoblasts remains unknown. Recently, a vesicular nucleotide transporter [VNUT, solute carrier family 17 member 9 (SLC17A9)] that preserves ATP in vesicles has been identified. The purpose of this study was to elucidate the role of VNUT in osteoblast bone metabolism. mRNA and protein expression of VNUT were confirmed in mouse bone and in osteoblasts by quantitative real-time PCR (qPCR) and immunohistochemistry. Next, when compressive force was applied to MC3T3-E1 cells by centrifugation, the expression of Slc17a9, P2x7r, and P2y2r was increased concomitant with an increase in extracellular ATP levels. Furthermore, compressive force decreased the osteoblast differentiation capacity of MC3T3-E1 cells. shRNA knockdown of Slc17a9 in MC3T3-E1 cells reduced levels of extracellular ATP and also led to increased osteoblast differentiation after the application of compressive force as assessed by qPCR analysis of osteoblast markers such as Runx2, Osterix, and alkaline phosphatase (ALP) as well as ALP activity. Consistent with these observations, knockdown of P2x7r or P2y2r by siRNA partially rescued the downregulation of osteoblast differentiation markers, caused by mechanical loading. In conclusion, our results demonstrate that VNUT is expressed in osteoblasts and that VNUT inhibits osteoblast differentiation in response to compressive force by mechanisms related to ATP release and P2X7R and/or P2Y2R activity., (© 2020 The Authors. Published by FEBS Press and John Wiley & Sons Ltd.)

Podosome formation in osteoclasts is an important initial step in osteoclastic bone resorption. Mice lacking c-Src (c-Src -/- ) exhibited osteopetrosis due to a lack of podosome formation in osteoclasts. We previously identified p130Cas (Crk-associated substrate [Cas]) as one of c-Src downstream molecule and osteoclast-specific p130Cas-deficient (p130Cas ΔOCL-/- ) mice also exhibited a similar phenotype to c-Src -/- mice, indicating that the c-Src/p130Cas plays an important role for bone resorption by osteoclasts. In this study, we performed a cDNA microarray and compared the gene profiles of osteoclasts from c-Src -/- or p130Cas ΔOCL-/- mice with wild-type (WT) osteoclasts to identify downstream molecules of c-Src/p130Cas involved in bone resorption. Among several genes that were commonly downregulated in both c-Src -/- and p130Cas ΔOCL-/- osteoclasts, we identified kinesin family protein 1c (Kif1c), which regulates the cytoskeletal organization. Reduced Kif1c expression was observed in both c-Src -/- and p130Cas ΔOCL-/- osteoclasts compared with WT osteoclasts. Kif1c exhibited a broad tissue distribution, including osteoclasts. Knockdown of Kif1c expression using shRNAs in WT osteoclasts suppressed actin ring formation. Kif1c overexpression restored bone resorption subsequent to actin ring formation in p130Cas ΔOCL-/- osteoclasts but not c-Src -/- osteoclasts, suggesting that Kif1c regulates osteoclastic bone resorption in the downstream of p130Cas (191 words). SIGNIFICANCE OF THE STUDY: We previously showed that the c-Src/p130Cas (Cas) plays an important role for bone resorption by osteoclasts. In this study, we identified kinesin family protein 1c (Kif1c), which regulates the cytoskeletal organization, as a downstream molecule of c-Src/p130Cas axis, using cDNA microarray. Knockdown of Kif1c expression using shRNAs in wild-type osteoclasts suppressed actin ring formation. Kif1c overexpression restored bone resorption subsequent to actin ring formation in osteoclast-specific p130Cas-deficient (p130Cas ΔOCL-/- ) osteoclasts but not c-Src -/- osteoclasts, suggesting that Kif1c regulates osteoclastic bone resorption in the downstream of p130Cas., (© 2019 John Wiley & Sons Ltd.)

Osteoclasts are multinuclear cells which maintain bone homeostasis by resorbing bone. During bone resorption, osteoclasts attach to the bone matrix via a sealing zone formed by an actin ring. Rous sarcoma oncogene (Src) is essential for actin ring formation and bone resorption. Recently, we demonstrated that plectin, a cytolinker protein, is a Src-binding protein in osteoclasts. However, the function of plectin in osteoclasts remains unknown. In this study, we demonstrated that shRNA knockdown of plectin in RAW 264.7 cells resulted in tartrate resistant acid phosphatase positive multinuclear cells (TRAP (+) MNCs) with impaired actin ring formation and bone resorption activity. Moreover, we found that in plectin-silenced TRAP (+) MNCs, Src and protein tyrosine kinase 2 beta (Pyk2), two critical kinases in osteoclastic bone resorption, were inactivated and microtubule polarity was disturbed. These results suggest that plectin plays a critical role in osteoclast biology by acting as a scaffold to facilitate Src and Pyk2 activation during microtubule organization., Competing Interests: Declaration of competing interest None., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Skeletal tissue homeostasis is maintained via the balance of osteoclastic bone resorption and osteoblastic bone formation. Autophagy and apoptosis are essential for the maintenance of homeostasis and normal development in cells and tissues. We found that Bax-interacting factor 1 (Bif-1/Endophillin B1/SH3GLB1), involving in autophagy and apoptosis, was upregulated during osteoclastogenesis. Furthermore, mature osteoclasts expressed Bif-1 in the cytosol, particularly the perinuclear regions and podosome, suggesting that Bif-1 regulates osteoclastic bone resorption. Bif-1-deficient (Bif-1 -/- ) mice showed increased trabecular bone volume and trabecular number. Histological analyses indicated that the osteoclast numbers increased in Bif-1 -/- mice. Consistent with the in vivo results, osteoclastogenesis induced by receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL) was accelerated in Bif-1 -/- mice without affecting RANKL-induced activation of RANK downstream signals, such as NF-κB and mitogen-activated protein kinases (MAPKs), CD115/RANK expression in osteoclast precursors, osteoclastic bone-resorbing activity and the survival rate. Unexpectedly, both the bone formation rate and osteoblast surface substantially increased in Bif-1 -/- mice. Treatment with β-glycerophosphate (β-GP) and ascorbic acid (A.A) enhanced osteoblastic differentiation and mineralization in Bif-1 -/- mice. Finally, bone marrow cells from Bif-1 -/- mice showed a significantly higher colony-forming efficacy by the treatment with or without β-GP and A.A than cells from wild-type (WT) mice, suggesting that cells from Bif-1 -/- mice had higher clonogenicity and self-renewal activity than those from WT mice. In summary, Bif-1 might regulate bone homeostasis by controlling the differentiation and function of both osteoclasts and osteoblasts (235 words)., (© 2019 Wiley Periodicals, Inc.)