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Transient receptor potential melastatin 7 (TRPM7) is a unique ion channel connected to a kinase domain. We previously demonstrated that Trpm7 expression is high in mouse ameloblasts and odontoblasts, and that amelogenesis is impaired in TRPM7 kinase‐dead mice. Here, we analyzed TRPM7 function during amelogenesis in Keratin 14‐Cre;Trpm7fl/fl conditional knockout (cKO) mice and Trpm7 knockdown cell lines. cKO mice showed lesser tooth pigmentation than control mice and broken incisor tips. Enamel calcification and microhardness were lower in cKO mice. Electron probe microanalysis (EPMA) showed that the calcium and phosphorus contents in the enamel were lower in cKO mouse than in control mice. The ameloblast layer in cKO mice showed ameloblast dysplasia at the maturation stage. The morphological defects were observed in rat SF2 cells with Trpm7 knockdown. Compared with mock transfectants, the Trpm7 knockdown cell lines showed lower levels of calcification with Alizarin Red‐positive staining and an impaired intercellular adhesion structures. These findings suggest that TRPM7 is a critical ion channel in enamel calcification for the effective morphogenesis of ameloblasts during amelogenesis. [ABSTRACT FROM AUTHOR]

Programmed cell death ligands (PD‐Ls) are expressed in tumor cells where they bind to programmed cell death‐1, an immunocyte co–receptor, resulting in tumor cell evasion from the immune system. Chemotherapeutic drugs have been recently reported to induce the expression of PD‐L, such as PD‐L1, in some cancer cells. However, little is known regarding PD‐L2 expression and its role in oral squamous cell carcinoma (OSCC). In this study, we examined the effect of cisplatin on the expression and regulation of PD‐L2 in OSCC cell lines and analyzed malignant behavior in PD‐L2‐expressing cells using colony, transwell and transformation assays. In addition, we examined PD‐L2 expression in the tumor tissues of OSCC patients using cytology and tissue microarray methods. In OSCC cell lines, cisplatin treatment upregulated PD‐L2 expression, along with that of the drug efflux transporter ABCG2, via signal transducers and activator of transcription (STAT) 1/3 activation. Moreover, PD‐L2‐positive or PD‐L2‐overexpressing cells demonstrated upregulation in both invasion and transformation ability but not in proliferation compared with PD‐L2‐negative or PD‐L2‐silencing cells. PD‐L2 expression was also observed in OSCC cells of cytology samples and tissue from OSCC patients. The intensity of PD‐L2 expression was correlated with more malignant morphological features in the histological appearance and an invasive pattern. Our findings indicate that cisplatin‐upregulated PD‐L2 expression in OSCC via STAT1/3 activation and the expression of PD‐L2 are likely to be associated with malignancy in OSCC. The PD‐L2 expression in cisplatin‐resistant OSCC cells may be a critical factor in prognosis of advanced OSCC patients. [ABSTRACT FROM AUTHOR]

Scaffolds implanted into bone defect sites must achieve optimal biodegradation rates while appropriately filling the void as new bone formation progresses. We recently developed a unique biomaterial consisting of salmon deoxyribose nucleic acid (DNA) and protamine, which can be used as an osteoconductive scaffold for tissue engineering. The aim of the present study was to elucidate how the degradation rate of the scaffold affects bone regeneration. We examined the relationships between the degradation rate of salmon DNA scaffolds and new bone formation using a rat skin flank subcutaneous model and rat calvarial defect model. The degradation rates of the scaffolds were proportional to the durations of pretreatment with ultraviolet (UV) light irradiation. The biodegradation rates of the scaffolds were also dependent on the duration of UV irradiation, as tested a subcutaneous tissue implantation. Scaffolds irradiated with UV light for 0.5 h maintained gradual biodegradation of phosphate compared with scaffolds irradiated for 0 or 3 h. In the calvarial defect model, we found that new bone formation was higher in rats treated with scaffolds irradiated with UV light for 0.5 h compared with those irradiated with UV light for 0 or 3.0 h. The present results suggest that bioengineering of scaffolds for biodegradation is important to regenerate bone. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 122–128, 2019. [ABSTRACT FROM AUTHOR]

Transient receptor potential type A1 ( TRPA1) is reported to be a Ca2+-permeable channel and is activated by cold temperatures and mechanical stimuli in the hair cells and in dorsal root ganglion. Using a DNA microarray, we found that TRPA1 was significantly up-regulated in human periodontal ligament (h PDL) cells 2 d after intermittent mechanical stimulation (i MS) loading compared with unloaded cells. Although h PDL cells are known to respond to mechanical stimulation induced by occlusal force, little is known about the expression and functional role of TRPA1 in these cells. Therefore, we investigated the effects of iMS on TRPA1 expression and its signaling pathway in h PDL cells. Intermittent mechanical stimulation loading up-regulated TRPA1 expression in hPDL cells in a time-dependent manner, but had no effect on other mechanoreceptors. Furthermore, iMS significantly increased the phosphorylation of mitogen-activated protein kinases ( MAPKs), especially extracellular signal-regulated kinase 1/2 ( ERK1/2) and p38, and the expression of C- C chemokine ligand 2 ( CCL2). Transient receptor potential type A1 agonists also increased MAPK phosphorylation and the intracellular Ca2+ concentration. By contrast, inhibition or silencing of TRPA1 partially suppressed i MS-induced MAPK phosphorylation. In summary, i MS during occlusion activates TRPA1 and MAPK signaling in periodontal ligament tissues, suggesting that TRPA1 regulates the mechanosensitivity of occlusal force via activation of MAPKs in h PDL cells. [ABSTRACT FROM AUTHOR]

Abstract: Purpose of the research: An oxidized form of guanine, 8-oxoGua, is known to have a potential to induce genetic mutations, thereby causing carcinogenesis. Mammalian cells hence have various mechanisms to eliminate 8-oxoGua in DNA and nucleotide pools. Since MutT-related enzymes, MTH1 and NUDT5, can hydrolyze 8-oxoGua-containing nucleotides in nucleotide pools, the expressions of MTH1 and NUDT5 are likely to be involved in controlling oxidation-induced carcinogenesis. In the present study, we examined the expressions of 8-oxoGua, MTH1, and NUDT5 in human normal keratinocytes and human oral squamous carcinoma cells treated with H2O2. Principal results: The immunofluorescent study demonstrated that the localization of 8-oxo-dGTP changed from cytoplasm to nucleus in the treatment with H2O2 in both cell types. The Western blotting analysis as well as RT-PCR revealed that H2O2 enhanced the expression of NUDT5, but not MTH1, in normal keratinocytes. The increased NUDT5 proteins were also detected in the nuclear extracts of keratinocytes treated with H2O2. In contrast, H2O2 had no effects on the expressions of NUDT5 and MTH1 in squamous carcinoma cells. Major conclusions: NUDT5 may thus be involved in preventing carcinogenic mutations in keratinocytes under oxidative stress, and its impaired expression may promote their carcinogenesis. [Copyright &y& Elsevier]

Although important roles of receptor activator of NF-κB ligand (RANKL) and its receptor (RANK) have been established for osteoclastogenesis and bone resorption, their expression and roles during physiological root resorption remain uncertain. Physiological root resorption for shedding of human deciduous teeth is mediated by osteoclast-like cells (odontoclasts). In this study, we examined the expression of RANKL and osteoprotegerin (OPG), a decoy receptor that prevents RANKL from binding to RANK in human periodontal ligament (PDL) cells during physiological root resorption using immunocytochemistry and reverse transcriptase polymerase chain reaction. The effect of RANKL on root resorbing activity of odontoclasts was evaluated by measuring the size of dissolved area on calcium phosphate-coated coverslips. The PDL cells isolated from either non-resorbing deciduous teeth or permanent teeth abundantly expressed OPG, but not RANKL. In contrast, PDL cells derived from resorbing deciduous teeth dominantly expressed RANKL. Human odontoclasts derived from resorbing deciduous teeth expressed both RANKL and RANK. It was observed that RANKL increased odontoclast actin ring formation and resorbing activity in a dose-dependent manner. These results indicate that PDL cells during the root-resorbing state express RANKL but decrease OPG expression. Expression of RANKL likely participates in odontoclastogenesis and activates physiological root resorption. [ABSTRACT FROM AUTHOR]