Ursoricin, a bacteriocin of Streptococcus ursoris, has potent activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci.

The emergence of drug-resistant bacteria, particularly methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), has increased the need to discover novel antimicrobial agents that are effective against these species. Here, we describe the identification and purification of the mutacin BHT-B-like gene locus and bacteriocin peptide from Streptococcus ursoris, which is closely related to Streptococcus ratti; hence, we named this bacteriocin ursoricin. Ursoricin is a cationic, chromosome-encoded peptide that has potent antimicrobial effects against Gram-positive pathogens, including MRSA and VRE, with minimum inhibitory concentrations in the micromolar range. Ursoricin also inhibits the biofilm formation of high biofilm-forming S. aureus. Antibacterial activity was retained after treatment at 100°C for 60 min at a pH range of 3-9 and was partially reduced by treatment with proteinase K for 2 h (63% residual activity). The potent anti-MRSA, anti-VRE, and antibiofilm effects of ursoricin suggest that it is a possible candidate for the treatment of MRSA, VRE, and biofilm-associated infections. IMPORTANCE: The emergence of multidrug-resistant bacteria worldwide has posed a significant public health threat and economic burdens that make the identification and development of novel antimicrobial agents urgent. Bacteriocins are promising new agents that exhibit antibacterial activity against a wide range of human pathogens. In this study, we report that the bacteriocin produced by Streptococcus ursoris showed good antibacterial activity against a wide range of Staphylococcus aureus and enterococcus strains, particularly methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and high biofilm-forming S. aureus. Interestingly, this bacteriocin had a stronger effect on S. aureus than on Staphylococcus epidermidis, which is a major commensal bacterium in human skin; this result is important when considering the disturbance of bacterial flora, especially on the skin, mediated by the application of antibacterial agents.

Opposing genetic polymorphisms of two ABC transporters contribute to the variation of nukacin resistance in Streptococcus mutans.

Streptococcus mutans is a cariogenic bacterium that produces a variety of bacteriocins and retains resistance to these bacteriocins. In this study, we investigated the susceptibility of 127 S. mutans strains to nukacins produced by Staphylococcus spp., which are commensal bacteria in humans. We detected diverse susceptibilities among strains. Nineteen strains had a disrupted LctF (type I), which is responsible for nukacin susceptibility, whereas the remaining 108 strains had an intact LctF (type II) and displayed resistance to nukacins. However, the type I strains still showed resistance to nukacins to some extent. Interestingly, 18/19 (94.7%) type I strains carried a mukA-T locus, which is related to the synthesis of mutacin K8, and mukFEG, an ABC transporter. In contrast, among type II strains, only 6/108 strains (5.6%) had both the mukA-T locus and mukFEG, 19/108 strains (17.6%) carried only mukFEG, and 83/108 strains (76.9%) harbored neither mukA-T nor mukFEG. We also found that MukF had two variants: 305 amino acids (type α) and 302 amino acids (type ß). All type I strains showed a type α (MukFα), whereas most type II strains with mukFEG (22/25 strains) had a type ß (MukFß). Then, we constructed a mukFEG-deletion mutant complemented with MukFαEG or MukFßEG and found that only MukFαEG was involved in nukacin resistance. The nukacin resistance capability of type II-LctFEG was stronger than that of MukFαEG. In conclusion, we identified a novel nukacin resistance factor, MukFEG, and either LctFEG or MukFEG was active in most strains via genetic polymorphisms depending on mukA-T genes. IMPORTANCE: Streptococcus mutans is an important pathogenic bacterium not only for dental caries but also for systemic diseases. S. mutans is known to produce a variety of bacteriocins and to retain resistance these bacteriocins. In this study, two ABC transporters, LctFEG and MukFEG, were implicated in nukacin resistance and each ABC transporter has two subtypes, active and inactive. Of the two ABC transporters, only one ABC transporter was always resistant, while the other ABC transporter was inactivated by genetic mutation. Interestingly, this phenomenon was defined by the presence or absence of the mutacin K8 synthesis gene region, one of the bacteriocins of S. mutans. This suggests that the resistance acquisition is tightly controlled in each strain. This study provides important evidence that the insertion of bacteriocin synthesis genes is involved in the induction of genetic polymorphisms and suggests that bacteriocin synthesis genes may play an important role in bacterial evolution.

Antibiotic susceptibility and genome analysis of Enterococcus species isolated from inpatients in one hospital with no apparent outbreak of vancomycin-resistant Enterococcus in Japan.

To prevent nosocomial infection, it is important to screen for potential vancomycin-resistant Enterococcus (VRE) among patients. In this study, we analyzed enterococcal isolates from inpatients in one hospital without any apparent outbreak of VRE. Enterococcal isolates were collected from inpatients at Hiroshima University Hospital from April 1 to June 30, 2021 using selective medium for Enterococci. Multilocus sequence typing, antimicrobial susceptibility testing, and whole-genome sequencing were performed. A total of 164 isolates, including Enterococcus faecium (41 isolates), Enterococcus faecalis (80 isolates), Enterococcus raffinosus (11 isolates), Enterococcus casseliflavus (nine isolates), Enterococcus avium (12 isolates), Enterococcus lactis (eight isolates), Enterococcus gallinarum (two isolates), and Enterococcus malodoratus (one isolate), were analyzed. We found one vanA-positive E. faecium, which was already informed when the patient was transferred to the hospital, nine vanC-positive E. casseliflavus, and two vanC-positive E. gallinarum. E. faecium isolates showed resistance to ampicillin (95.1%), imipenem (95.1%), and levofloxacin (87.8%), and E. faecalis isolates showed resistance to minocycline (49.4%). Ampicillin- and levofloxacin-resistant E. faecium had multiple mutations in penicillin-binding protein 5 (PBP5) (39/39 isolates) and ParC/GyrA (21/36 isolates), respectively. E. raffinosus showed resistance to ampicillin (81.8%), imipenem (45.5%), and levofloxacin (45.5%), and E. lactis showed resistance to ampicillin (37.5%) and imipenem (50.0%). The linezolid resistance genes optrA and cfr(B) were found only in one isolate of E. faecalis and E. raffinosus, respectively. This study, showing the status of enterococci infection in hospitalized patients, is one of the important information when considering nosocomial infection control of VRE.

Relationship between CD4+ T-cell counts at baseline and initial periodontal treatment efficacy in patients undergoing treatment for HIV infection: A retrospective observational study.

AIM: To retrospectively investigate the relationship between the CD4+ T-cell counts at baseline and the efficacy of the initial periodontal treatment of patients undergoing treatment for human immunodeficiency virus (HIV) infection using the periodontal inflamed surface area (PISA). MATERIALS AND METHODS: Thirty-three patients with chronic periodontitis who had undergone periodontal examination at baseline and after the initial periodontal treatment were enrolled. PISA was calculated from the periodontal probing depth and bleeding on probing, and the ratio of PISA after treatment to that at baseline (PISA response ratio) was calculated. Groups with a response ratio of <1 and ≥1 were defined as the improvement and the non-improvement groups, respectively. RESULTS: PISA after the initial periodontal treatment significantly decreased compared with that at baseline (p < .05). A weak negative correlation was found between the PISA response ratio and CD4+ T-cell counts at baseline (p < .05). The CD4+ T-cell counts at baseline were significantly higher in the improvement group than in the non-improvement group (p < .05). Multivariate analysis revealed that the CD4+ T-cell counts at baseline was an independent factor that affects the PISA (p < .05). CONCLUSIONS: The higher the CD4+ T-cell counts at baseline in patients undergoing treatment for HIV infection, the more effective the initial periodontal treatment.

In Situ Raman Analysis of Biofilm Exopolysaccharides Formed in Streptococcus mutans and Streptococcus sanguinis Commensal Cultures.

This study probed in vitro the mechanisms of competition/coexistence between Streptococcus sanguinis (known for being correlated with health in the oral cavity) and Streptococcus mutans (responsible for aciduric oral environment and formation of caries) by means of quantitative Raman spectroscopy and imaging. In situ Raman assessments of live bacterial culture/coculture focusing on biofilm exopolysaccharides supported the hypothesis that both species engaged in antagonistic interactions. Experiments of simultaneous colonization always resulted in coexistence, but they also revealed fundamental alterations of the biofilm with respect to their water-insoluble glucan structure. Raman spectra (collected at fixed time but different bacterial ratios) showed clear changes in chemical bonds in glucans, which pointed to an action by Streptococcus sanguinis to discontinue the impermeability of the biofilm constructed by Streptococcus mutans. The concurrent effects of glycosidic bond cleavage in water-insoluble α - 1,3-glucan and oxidation at various sites in glucans' molecular chains supported the hypothesis that secretion of oxygen radicals was the main "chemical weapon" used by Streptococcus sanguinis in coculture.

Retrospective study on the therapeutic efficacy of zinc acetate hydrate administration to patients with hypozincemia-induced dysgeusia.

BACKGROUND: Dysgeusia is a relatively early symptom of zinc deficiency, and zinc replacement is effective in treating dysgeusia. The administration of zinc acetate hydrate (ZAH) was approved in 2017 for patients with hypozincemia in Japan. This retrospective study was conducted to explore the efficacy and safety of ZAH administration in patients with hypozincemia-induced dysgeusia. METHODS: Patients with hypozincemia-induced dysgeusia who visited our hospital from May 2013 to December 2019 were included in this study. ZAH (zinc content; 50 mg/day) was administered to 42 patients for 24 weeks. The taste test was performed using the filter paper disk method, and the total cognitive thresholds of the left and right chorda tympani regions were used. Changes in taste function, serum zinc and copper levels, and copper/zinc ratio were analyzed. A total of 28 patients who received polaprezinc (PPZ, zinc content; 34 mg/day) for 24 weeks, who were prescribed until ZAH was approved, were registered as controls. RESULTS: Serum zinc levels at 12 and 24 weeks after ZAH or PPZ administration were higher than those before administration. These levels were significantly higher in the ZAH-treated group than in the PPZ-treated group. However, serum copper levels did not significantly change before and after administration. In the taste test, the taste thresholds for the acidity and salty at 12 and 24 weeks after ZAH administration were significantly decreased compared to before administration. In contrast, in the PPZ group, the taste thresholds for the acidity and salty were significantly decreased 24 weeks after administration. CONCLUSIONS: ZAH (50 mg/day) administration was effective in improving the gustatory sensitivity of patients with dysgeusia and hypozincemia 12 weeks after administration without affecting the serum copper level. ZAH was also more effective than PPZ.

Periapical lesion following Cnm-positive Streptococcus mutans pulp infection worsens cerebral hemorrhage onset in an SHRSP rat model.

Cerebral hemorrhage severely affects the daily life of affected individuals. Streptococcus mutans and its adhesion factor Cnm increase the adverse effects of cerebral hemorrhages. However, the mechanism by which Cnm-positive bacteria migrate from apical lesions to cerebral hemorrhage sites is unclear. Therefore, we established an S. mutans-infected apical lesion in a rat model of hypertension and investigated the neurological symptoms associated with cerebral hemorrhage. Eighteen 12-week-old stroke-prone spontaneously hypertensive rats were randomly divided into three groups, i.e. the no infection (control), dental infection with S. mutans KSM153 wild type (Cnm positive), and KSM153 Δcnm groups. Immunofluorescent staining was performed to visualize S. mutans protein. Serum interleukin-1ß levels were measured. The adhesion of S. mutans to the extracellular matrix and human fibroblast cells was also analyzed. Serum antibody titers against S. mutans were comparable between Cnm positive and knockout mutants. However, 3-10 days post-infection, neurological symptom scores and cerebral hemorrhage scores were higher in Cnm-positive rats than in knockout mutants. The localization of S. mutans-derived protein was observed in the vicinity of disrupted blood vessels. Serum interleukin-1ß levels significantly increased post-KSM153 WT infection. Cnm-positive S. mutans clinical isolates showed increased adhesion to the extracellular matrix, human dental pulp cells, and human umbilical vein endothelial cells compared with the Cnm-negative S. mutans isolates. In conclusion, Cnm-positive bacteria colonize the apical lesion site using the extracellular matrix as a foothold and affect cerebral hemorrhage via the bloodstream.

Oxytocin suppresses CXCL10 production in TNF-α-stimulated human dental pulp stem cells.

Oxytocin (OX) is a posterior pituitary hormone secreted into the blood from axon terminals projecting from the posterior pituitary. Recent reports indicate OX plays an important role in the progression of inflammatory diseases such as rheumatoid arthritis. Pulpitis is caused by the activation of the biological defense mechanism of the dental pulp against cariogenic bacteria. However, the role of OX in the pathogenesis of pulpitis remains unknown. The aim of this study was to examine the effect of OX on CXC chemokine ligand 10 (CXCL10) production in human dental pulp stem cells (HDPSCs). Expression of the oxytocin receptor (OXR) on HDPSCs was detected by Western blot analysis and immunofluorescence. CXCL10 production in HDPSCs was measured using an enzyme-linked immunosorbent assay kit. Western blot analysis was performed to determine the phosphorylation levels of signal transduction molecules, including nuclear factor kappa B, mitogen-activated protein kinases (MAPKs), and Akt in HDPSCs. HDPSCs expressed OXR. OX significantly decreased CXCL10 production in tumor necrosis factor (TNF)-α-stimulated HDPSCs. The p38 MAPK and Akt pathways were related to the OX-suppressed CXCL10 production in TNF-α-stimulated HDPSCs. These results indicate that OX appears to modulate the immune response in pulpitis via suppression of CXCL10 production by HDPSCs.

Oxidative stress impairs the calcification ability of human dental pulp cells.

BACKGROUND: The relationship between internal root resorption and oxidative stress has not yet been reported. This study aimed to add molecular insight into internal root resorption. The present study was conducted to investigate the effect of hydrogen peroxide (H2O2) as an inducer of oxidative stress on the calcification ability of human dental pulp cells (hDPCs) and the involvement of inositol 1, 4, 5-trisphosphate (IP3). MATERIAL AND METHODS: hDPCs (Lonza, Basel, Switzerland) were exposed to H2O2. Cell viability and reactive oxygen species (ROS) production were then evaluated. To investigate the effect of H2O2 on the calcification ability of hDPCs, real-time PCR for alkaline phosphatase (ALP) mRNA expression, ALP staining, and Alizarin red staining were performed. Data were compared with those of hDPCs pretreated with 2-aminoethyldiphenylborate (2-APB), which is an IP3 receptor inhibitor. RESULTS: H2O2 at concentrations above 250 µM significantly reduced cell viability (P < 0.01). More ROS production occurred in 100 µM H2O2-treated hDPCs than in control cells (P < 0.01). 2-APB significantly decreased the production (P < 0.05). H2O2-treated hDPCs showed significant reductions in ALP mRNA expression (P < 0.01), ALP activity (P < 0.01), and mineralized nodule deposition compared with negative control cells (P < 0.01). 2-APB significantly inhibited these reductions (P < 0.01, P < 0.05 and P < 0.01, respectively). Data are representative of three independent experiments with three replicates for each treatment and values are expressed as means ± SD. CONCLUSION: To the best of our knowledge, this is the first study documenting the involvement of IP3 signaling in the calcification ability of human dental pulp cells impaired by H2O2.

DMP-1 promoter-associated antisense strand non-coding RNA, panRNA-DMP-1, physically associates with EGFR to repress EGF-induced squamous cell carcinoma migration.

Accumulating evidence suggests that specific non-coding RNAs exist in many types of malignant tissues, and are involved in cancer invasion and metastasis. However, little is known about the precise roles of non-coding RNAs in squamous cell carcinoma (SQCC) invasion and migration. Recently, the dentin matrix protein-1 (DMP-1) gene locus was identified as a transcriptionally active site in squamous cell carcinoma (SQCC) tissue and cells. However, it is unclear whether RNA associated with cell migration exist at the DMP-1 gene locus in SQCC cells. We identified a novel promoter-associated non-coding RNA in the antisense strand of DMP-1 gene locus, promoter-associated non-coding RNA (panRNA)-DMP-1, by the RACE method in SQCC cells and tissues, and characterized the functions of panRNA-DMP-1 in EGF-driven SQCC cell migration. The inhibition of endogenous panRNA-DMP-1 expression by specific siRNAs and exogenous over-expression of panRNA-DMP-1 resulted in increased and suppressed cellular migration toward EGF in SQCC cells, respectively, and nuclear expression of panRNA-DMP-1 was induced by EGF stimulation. Mechanistically, suppression of panRNA-DMP-1 expression increased EGFR nuclear localization upon EGF treatment and nuclear panRNA-DMP-1 physically interacted with EGFR, which was confirmed by RNA immunoprecipitation assay using a bacteriophage-delivered PP7 RNA labeling system. Furthermore, co-immunoprecipitation assay revealed that suppression of panRNA-DMP-1 stabilized EGFR interaction with STAT3, a known co-transcription factors of EGFR, to induce migratory properties in many cancer cells. Based on these findings, panRNA-DMP-1 is an EGFR-associating RNA that inhibits the EGF-induced migratory properties of SQCC possibly by regulating EGFR nuclear localization and EGFR binding to STAT3.

Semaphorin3A released from human dental pulp cells inhibits the increase in interleukin-6 and CXC chemokine ligand 10 production induced by tumor necrosis factor-α through suppression of nuclear factor-κB activation.

Human dental pulp cells (HDPCs) play an important role in pulpitis. Semaphorin3A (Sema3A), which is an axon guidance molecule, is a member of the secretory semaphorin family. Recently, Sema3A has been reported to be an osteoprotective factor and to be involved in the immune response. However, the role of Sema3A in dental pulp inflammation remains unknown. The aim of this study was to reveal the existence of Sema3A in human dental pulp tissue and the effect of Sema3A which is released from tumor necrosis factor (TNF)-α-stimulated HDPCs on production of proinflammatory cytokines, such as interleukin (IL)-6 and CXC chemokine ligand 10 (CXCL10), from HDPCs stimulated with TNF-α. Sema3A was detected in inflamed pulp as compared to normal pulp. HDPCs expressed Neuropilin-1(Nrp1) which is Sema3A receptor. TNF-α increased the levels of IL-6 and CXCL10 in HDPCs in time-dependent manner. Sema3A inhibited production of these two cytokines from TNF-α-stimulated HDPCs. TNF-α induced soluble Sema3A production from HDPCs. Moreover, antibody-based neutralization of Sema3A further promoted production of IL-6 and CXCL10 from TNF-α-stimulated HDPCs. Sema3A inhibited nuclear factor (NF)-κB P65 phosphorylation and inhibitor κBα degradation in TNF-α-stimulated HDPCs. These results indicated that Sema3A is induced in human dental pulp, and TNF-α acts on HDPCs to produce Sema3A, which partially inhibits the increase in IL-6 and CXCL10 production induced by TNF-α, and that the inhibition leads to suppression of NF-κB activation. Therefore, it is suggested that Sema3A may regulate inflammation in dental pulp and be novel antiinflammatory target molecule for pulpitis.

Involvement of Rac1 in macrophage activation by brain-derived neurotrophic factor.

Brain-derived neurotrophic factor (BDNF) enhances periodontal tissue regeneration. Tissue regeneration is characterized by inflammation, which directs the quality of tissue repair. This study aimed to investigate the effect of BDNF on the phagocytic activity of RAW264.7 cells. In addition, we studied the effect of BDNF on guanosine triphosphatase (GTP)-RAS-related C3 botulinus toxin substrate (Rac)1 and phospho-Rac1 levels in RAW264.7 cells. Rac1 inhibitor inhibited BDNF-induced phagocytosis of latex-beads. In addition, BDNF enhanced Porphyromonas gingivalis (Pg) phagocytosis by RAW264.7 cells as well as latex-beads. We demonstrated for the first time that BDNF enhances phagocytic activity of RAW264.7 cells through Rac1 activation. The present study proposes that BDNF may reduce inflammatory stimuli during BDNF-induced periodontal tissue regeneration through enhanced phagocytic activity of macrophages.

PPARγ-Induced Global H3K27 Acetylation Maintains Osteo/Cementogenic Abilities of Periodontal Ligament Fibroblasts.

The periodontal ligament is a soft connective tissue embedded between the alveolar bone and cementum, the surface hard tissue of teeth. Periodontal ligament fibroblasts (PDLF) actively express osteo/cementogenic genes, which contribute to periodontal tissue homeostasis. However, the key factors maintaining the osteo/cementogenic abilities of PDLF remain unclear. We herein demonstrated that PPARγ was expressed by in vivo periodontal ligament tissue and its distribution pattern correlated with alkaline phosphate enzyme activity. The knockdown of PPARγ markedly reduced the osteo/cementogenic abilities of PDLF in vitro, whereas PPARγ agonists exerted the opposite effects. PPARγ was required to maintain the acetylation status of H3K9 and H3K27, active chromatin markers, and the supplementation of acetyl-CoA, a donor of histone acetylation, restored PPARγ knockdown-induced decreases in the osteo/cementogenic abilities of PDLF. An RNA-seq/ChIP-seq combined analysis identified four osteogenic transcripts, RUNX2, SULF2, RCAN2, and RGMA, in the PPARγ-dependent active chromatin region marked by H3K27ac. Furthermore, RUNX2-binding sites were selectively enriched in the PPARγ-dependent active chromatin region. Collectively, these results identified PPARγ as the key transcriptional factor maintaining the osteo/cementogenic abilities of PDLF and revealed that global H3K27ac modifications play a role in the comprehensive osteo/cementogenic transcriptional alterations mediated by PPARγ.

Optineurin regulates osteoblastogenesis through STAT1.

A sophisticated and delicate balance between bone resorption by osteoclasts and bone formation by osteoblasts regulates bone metabolism. Optineurin (OPTN) is a gene involved in primary open-angle glaucoma and amyotrophic lateral sclerosis. Although its function has been widely studied in ophthalmology and neurology, recent reports have shown its possible involvement in bone metabolism through negative regulation of osteoclast differentiation. However, little is known about the role of OPTN in osteoblast function. Here, we demonstrated that OPTN controls not only osteoclast but also osteoblast differentiation. Different parameters involved in osteoblastogenesis and osteoclastogenesis were assessed in Optn-/- mice. The results showed that osteoblasts from Optn-/- mice had impaired alkaline phosphatase activity, defective mineralized nodules, and inability to support osteoclast differentiation. Moreover, OPTN could bind to signal transducer and activator of transcription 1 (STAT1) and regulate runt-related transcription factor 2 (RUNX2) nuclear localization by modulating STAT1 levels in osteoblasts. These data suggest that OPTN is involved in bone metabolism not only by regulating osteoclast function but also by regulating osteoblast function by mediating RUNX2 nuclear translocation via STAT1.

Aggressive periodontitis and NOD2 variants.

Aggressive periodontitis (AgP) occurs at an early age and causes rapid periodontal tissue destruction. Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) encodes a protein with two caspase recruitment domains and eleven leucine-rich repeats. This protein is expressed mainly in peripheral blood leukocytes and is involved in immune response. NOD2 variants have been associated with increased susceptibility to Crohn's disease, and recently, NOD2 was reported as a causative gene in AgP. The present study aimed to identify potential NOD2 variants in an AgP cohort (a total of 101 patiens: 37 patients with positive family histories and 64 sporadic patients). In the familial group, six patients from two families had a reported heterozygous missense variant (c.C931T, p.R311W). Four patients in the sporadic group had a heterozygous missense variant (c.C1411T, p.R471C), with no reported association to the disease. Overall, two NOD2 variants, were identified in 10% of our AgP cohort. These variants were different from the major variants reported in Crohn's disease. More cases need to be investigated to elucidate the role of NOD2 variants in AgP pathology.

A small nuclear acidic protein (MTI-II, Zn2+-binding protein, parathymosin) attenuates TNF-α inhibition of BMP-induced osteogenesis by enhancing accessibility of the Smad4-NF-κB p65 complex to Smad binding element.

Pro-inflammatory cytokines prevent bone regeneration in vivo and activation of nuclear factor-κB (NF-κB) signaling has been proposed to lead to suppression of bone morphogenetic protein (BMP)-induced osteogenesis via direct binding of p65 to Smad4 in vitro. Application of a small nuclear acidic protein (MTI-II) and its delivered peptide, MPAID (MTI-II peptide anti-inflammatory drug) has been described to elicit therapeutic potential via strong anti-inflammatory action following the physical association of MTI-II and MPAID with p65. However, it is unclear whether MTI-II attenuates tumor necrosis factor (TNF)-α inhibition of BMP-induced osteogenesis. Herein, we found that TNF-α-mediated suppression of responses associated with BMP4-induced osteogenesis, including expression of the osteocalcin encoding gene Ocn, Smad binding element (SBE)-dependent luciferase activity, alkaline phosphatase activity, and alizarin red S staining were largely restored by MTI-II and MPAID in MC3T3-E1 cells. Mechanistically, MTI-II and MPAID did not inhibit nuclear translocation of p65 or disassociate Smad4 from p65. Further, results from chromatin immunoprecipitation (ChIP) analyses revealed that Smad4 enrichment in cells over-expressing MTI-II and treated with TNF-α was equivalent to that in cells without TNF-α treatment. Alternatively, Smad4 enrichment was considerably decreased following TNF-α treatment in control cells. Moreover, p65 enrichment in the Id-1 promoter SBE was detected only when cells over-expressing MTI-II were stimulated with TNF-α. Overall, our study concludes that MTI-II restored TNF-α-inhibited suppression of BMP-Smad-induced osteogenic differentiation by enhancing accessibility of the Smad4-p65 complex to the SBE rather than by liberating Smad4 from p65.

Genome-wide identification of chromatin-enriched RNA reveals that unspliced dentin matrix protein-1 mRNA regulates cell proliferation in squamous cell carcinoma.

Chromatin-enriched noncoding RNAs (ncRNAs) have emerged as key molecules in epigenetic processes by interacting with chromatin-associated proteins. Recently, protein-coding mRNA genes have been reported to be chromatin-tethered, similar with ncRNA. However, very little is known about whether chromatin-enriched mRNA is involved in the chromatin modification process. Here, we comprehensively examined chromatin-enriched RNA in squamous cell carcinoma (SQCC) cells by RNA subcellular localization analysis, which was a combination of RNA fractionation and RNA-seq. We identified 11 mRNAs as highly chromatin-enriched RNAs. Among these, we focused on the dentin matrix protein-1 (DMP-1) gene because its expression in SQCC cells has not been reported. Furthermore, we clarified that DMP-1 mRNA was retained in chromatin in its unspliced form in SQCC in vitro and in vivo. As the inhibition of the unspliced DMP-1 mRNA (unspDMP-1) expression resulted in decreased cellular proliferation in SQCC cells, we performed ChIP-qPCR to identify cell cycle-related genes whose expression was epigenetically modified by unspDMP-1, and found that the CDKN1B promoter became active in SQCC cells by inhibiting unspDMP-1 expression. This result was further validated by the increased CDKN1B gene expression in the cells treated with siRNA for unspDMP-1 and by restoration of the decreased cellular proliferation rate by simultaneously inhibiting CDKN1B expression in SQCC cells. Further, to examine whether unspDMP-1 was able to associate with the CDKN1B promoter region, SQCC cells stably expressing PP7-mCherry fusion protein were transiently transfected with the unspDMP-1 fused to 24 repeats of the PP7 RNA stem loop (unspDMP-1-24xPP7) and we found that unspDMP-1-24xPP7 was efficiently precipitated with the antibody against mCherry and was significantly enriched in the CDKN1B promoter region. Thus, unspDMP-1 is a novel chromatin-enriched RNA that epigenetically regulates cellular proliferation of SQCC.

Aggregatibacter actinomycetemcomitans outer membrane protein 29 (Omp29) induces TGF-ß-regulated apoptosis signal in human gingival epithelial cells via fibronectin/integrinß1/FAK cascade.

Gingival junctional epithelial cell apoptosis caused by periodontopathic bacteria exacerbates periodontitis. This pathological apoptosis is involved in the activation of transforming growth factor ß (TGF-ß). However, the molecular mechanisms by which microbes induce the activation of TGF-ß remain unclear. We previously reported that Aggregatibacter actinomycetemcomitans (Aa) activated TGF-ß receptor (TGF-ßR)/smad2 signalling to induce epithelial cell apoptosis, even though Aa cannot bind to TGF-ßR. Additionally, outer membrane protein 29 kDa (Omp29), a member of the Aa Omps family, can induce actin rearrangements via focal adhesion kinase (FAK) signalling, which also plays a role in the activation of TGF-ß by cooperating with integrin. Accordingly, we hypothesized that Omp29-induced actin rearrangements via FAK activity would enhance the activation of TGF-ß, leading to gingival epithelial cell apoptosis in vitro. By using human gingival epithelial cell line OBA9, we found that Omp29 activated TGF-ßR/smad2 signalling and decreased active TGF-ß protein levels in the extracellular matrix (ECM) of cell culture, suggesting the transactivation of TGF-ßR. Inhibition of actin rearrangements by cytochalasin D or blebbistatin and knockdown of FAK or integrinß1 expression by siRNA transfection attenuated TGF-ßR/smad2 signalling activity and reduction of TGF-ß levels in the ECM caused by Omp29. Furthermore, Omp29 bound to fibronectin (Fn) to induce its aggregation on integrinß1, which is associated with TGF-ß signalling activity. All the chemical inhibitors and siRNAs tested blocked Omp29-induced OBA9 cells apoptosis. These results suggest that Omp29 binds to Fn in order to facilitate Fn/integrinß1/FAK signalling-dependent TGF-ß release from the ECM, thereby inducing gingival epithelial cell apoptosis via TGF-ßR/smad2 pathway.

Distinction Between Cell Proliferation and Apoptosis Signals Regulated by Brain-Derived Neurotrophic Factor in Human Periodontal Ligament Cells and Gingival Epithelial Cells.

Previously, we reported that brain-derived neurotrophic factor (BDNF) enhances periodontal tissue regeneration by inducing periodontal ligament cell proliferation in vivo. In addition, the down growth of gingival epithelial cells, which comprises a major obstacle to the regeneration, was not observed. However, the underlying molecular mechanism is still unclear. Therefore, this study aimed to investigate the effect of BDNF on cell proliferation and apoptosis in human periodontal ligament (HPL) cells and human gingival epithelial cells (OBA9 cells) and to explore the molecular mechanism in vitro. HPL cells dominantly expressed a BDNF receptor, TrkB, and BDNF increased cell proliferation and ERK phosphorylation. However, its proliferative effect was diminished by a MEK1/2 inhibitor (U0126) and TrkB siRNA transfection. Otherwise, OBA9 cells showed a higher expression level of p75, which is a pan-neurotrophin receptor, than that of HPL cells. BDNF facilitated not cell proliferation but cell apoptosis and JNK phosphorylation in OBA9 cells. A JNK inhibitor (SP600125) and p75 siRNA transfection attenuated the BDNF-induced cell apoptosis. Moreover, OBA9 cells pretreated with SP600125 or p75 siRNA showed cell proliferation by BDNF stimulation, though it was reduced by U0126 and TrkB siRNA. Interestingly, overexpression of p75 in HPL cells upregulated cell apoptosis and JNK phosphorylation by BDNF treatment. These results indicated that TrkB-ERK signaling regulates BDNF-induced cell proliferation, whereas p75-JNK signaling plays roles in cell apoptotic and cytostatic effect of BDNF. Overall, BDNF activates periodontal ligament cells proliferation and inhibits the gingival epithelial cells growth via the distinct pathway. J. Cell. Biochem. 117: 1543-1555, 2016. © 2015 Wiley Periodicals, Inc.

Sequential process in brain-derived neurotrophic factor-induced functional periodontal tissue regeneration.

We recently demonstrated that brain-derived neurotrophic factor (BDNF) promotes periodontal tissue regeneration. The purpose of this study was to establish an essential component of a rational approach for the clinical application of BDNF in periodontal regenerative therapy. Here, we assessed the sequence of early events in BDNF-induced periodontal tissue regeneration, especially from the aspect of cementum regeneration. Brain-derived neurotrophic factor was applied into experimental periodontal defects in Beagle dogs. The localization of cells positive for neurotrophic tyrosine kinase, receptor, type 2, proliferating cell nuclear antigen, osteopontin, integrin αVß3, and integrin α2ß1 was evaluated by immunohistochemistry. The effects of BDNF on adhesion of cultured human periodontal ligament cells was examined by an in vitro study. The results suggest that BDNF could induce rapid cementum regeneration by stimulating adhesion, proliferation, and differentiation of periodontal ligament cells in the early regenerative phase, resulting in enhancement of periodontal tissue regeneration.