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Dental caries is a chronic, infectious, and destructive disease that allows bacteria to break into the dental pulp tissue. As caries-related bacteria invade the human dentinal tubules, odontoblasts are the first line of dental pulp that trigger the initial inflammatory and immune responses. DNA methylation is a key epigenetic modification that plays a fundamental role in gene transcription, and its role in inflammation-related diseases has recently attracted attention. However, whether DNA methylation regulates the inflammatory response of human odontoblasts is still unknown. In the present study, we investigated the expression of DNA methyltransferase (DNMT)-1 in lipoteichoic acid (LTA)-stimulated human odontoblast-like cells (hOBs) and found that DNMT1 expression showed a decline that is contrary to the transcription of inflammatory cytokines. Knockdown of the DNMT1 gene increased the expression of several cytokines, including IL-6 and IL-8, in the LTA-induced inflammatory response. DNMT1 knockdown increased the phosphorylation of IKKα/β, IκBα, and p65 in the NF-κB pathway and the phosphorylation of p38 and ERK in the MAPK pathway; however, only the NF-κB pathway inhibitor PDTC suppressed both IL-6 and IL-8 expression, whereas inhibitors of the MAPK pathway (U0126, SB2035580, and SP600125) did not. Furthermore, DNMT1 knockdown upregulated the expression of MyD88 and TRAF6 but only attenuated the MyD88 gene promoter methylation in LTA-treated hOBs. Taken together, these results demonstrated that DNMT1 depletion caused hypomethylation and upregulation of MyD88, which resulted in activation of the NF-κB pathway and the subsequent release of LTA-induced inflammatory cytokines in hOBs. This study emphasizes the critical role of DNA methylation in the immune defense of odontoblasts when dental pulp reacted to caries. [ABSTRACT FROM AUTHOR]

Testis-specific gene 13 (TSGA13) is abundantly expressed in testis. As previous studies of TSGA13 expression pattern have all been based on mRNA analysis, it is imperative to investigate its actual protein expression. Here, we first examined TSGA13 gene tree and protein homology among species, and found that TSGA13 is relatively well conserved. Next, we detected its protein expression in normal human tissues as well as in a limited number of malignant tumors by immunohistochemistry (IHC). It was demonstrated that, in addition to testis, high expression of TSGA13 could also be observed in multiple normal tissues, including stomach, larynx, spleen, bladder, tonsil, liver and thyroid. Notably, most types of human carcinoma tissues displayed reduced expression of TSGA13 rather than their adjacent normal tissues except glioblastoma and lung cancer. Hence, the data from the current study strongly suggest the association between TSGA13 and tumor malignancy. [ABSTRACT FROM AUTHOR]