Glucosyltransferases (Gtfs) play critical roles in the etiology and pathogenesis of Streptococcus mutans (S. mutans)- mediated dental caries including early childhood caries. Gtfs enhance the biofilm formation and promotes colonization of cariogenic bacteria by generating biofilm extracellular polysaccharides (EPSs), the key virulence property in the cariogenic process. Therefore, Gtfs have become an appealing target for effective therapeutic interventions that inhibit cariogenic biofilms. Importantly, targeting Gtfs selectively impairs the S. mutans virulence without affecting S. mutans existence or the existence of other species in the oral cavity. Over the past decade, numerous Gtfs inhibitory molecules have been identified, mainly including natural and synthetic compounds and their derivatives, antibodies, and metal ions. These therapeutic agents exert their inhibitory role in inhibiting the expression gtf genes and the activities and secretion of Gtfs enzymes with a wide range of sensitivity and effectiveness. Understanding molecular mechanisms of inhibiting Gtfs will contribute to instructing drug combination strategies, which is more effective for inhibiting Gtfs than one drug or class of drugs. This review highlights our current understanding of Gtfs activities and their potential utility, and discusses challenges and opportunities for future exploration of Gtfs as a therapeutic target.
Biofilms ; Dental Caries/prevention & control* ; Glucosyltransferases/antagonists & inhibitors* ; Humans ; Streptococcus mutans/enzymology*

OBJECTIVETo investigate the mechanism of lemon peel essential oil (LPE) on the cariogenicity of Streptococcus sobrinus (Ss).

METHODSLPE was extracted by the authors, and the minimum inhibition concentration (MIC) was measured by disc diffusion method. The LPE was used as the experimental group with concentrations ranging from 2.250 g/L to 0.281 g/L prepared with trypticase peptone yeast (TPY) culture medium, and TPY culture medium was used as the control group. Ss at the concentration of 10(8) CFU/ml was added to each group, and cultured for 6, 18, 24, 48 hours. Neson-Somogyi method was used to measure the content of reducing sugar, and glucosyltransferase (GTF) activity. The activity of lactate dehydrogenase (LDH) was measured by lactic acid and pyruvic acid continuous monitoring method. The content of water insoluble glucan (WIG) was measured by anthrone method, and the pH value of the culture solution was detected. The value of pH before the experiment and the time difference was alculated as ΔpH.

RESULTSAt the same time point, the activity of GTF and LDH and the concentration of WIG and the value ΔpH decreased gradually with the increase of concentration of LPE. There were significant differences between each experimental group and control group (P < 0.01). The control group had the maximum value, GTF: (6.71 ± 0.61) mIU, LDH: (135.8 ± 1.7) U/L, WIG: (47.15 ± 5.12) mg/L, ΔpH: (2.67 ± 0.01). The highest drug concentration group had the minimum value: GTF: (0.39 ± 0.07) mIU, LDH: (95.0 ± 5.4) U/L, WIG: (2.44 ± 0.38) mg/L, ΔpH: (0.61 ± 0.01).

CONCLUSIONSThe LPE below the MIC could still inhibit the GTF, LDH activity and lead to the decrease of WIG and the acid production.

Dose-Response Relationship, Drug ; Glucans ; biosynthesis ; Glucosyltransferases ; antagonists & inhibitors ; metabolism ; Lactate Dehydrogenases ; antagonists & inhibitors ; metabolism ; Microbial Sensitivity Tests ; Oils, Volatile ; pharmacology ; Plant Oils ; pharmacology ; Streptococcus sobrinus ; drug effects ; metabolism

OBJECTIVETo evaluate the effect of mifepristone in reversing multidrug resistance(MDR) and modulating glucosylceramide synthase (GCS) mRNA expression in human ovarian cancer COC(1)/DDP cells.

METHODSMDR cell line COC(1)/DDP was treated with mifepristone at different concentrations. The alterations in the chemosensitivity of the cells to cisplatin (DDP) were evaluated by MTT assay. GCS mRNA expression in COC(1)/DDP cells were detected using RT-PCR before and after mifepristone treatment.

RESULTSThe expression level of GCS mRNA was 1.1792 in COC(1)/DDP cells, significantly higher than that in COC(1) cells (0.2836). Mifepristone at 1.25-10 micromol/L increased the sensitivity of COC(1)/DDP cells to cisplatin, and inhibited GCS expression at the mRNA level, showing concentration-dependent modulation of MDR and gene expression in the cells.

CONCLUSIONMifepristone can dose-dependently lower cisplatin resistance of COC(1)/DDP cells, the mechanism of which involves inhibition of GCS expression.

Antineoplastic Agents ; pharmacology ; Cell Line, Tumor ; Cisplatin ; pharmacology ; Dose-Response Relationship, Drug ; Drug Resistance, Multiple ; drug effects ; Drug Resistance, Neoplasm ; drug effects ; Female ; Gene Expression Regulation, Enzymologic ; drug effects ; Gene Expression Regulation, Neoplastic ; drug effects ; Glucosyltransferases ; genetics ; Hormone Antagonists ; pharmacology ; Humans ; Mifepristone ; pharmacology ; Ovarian Neoplasms ; enzymology ; genetics ; pathology ; RNA, Messenger ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction

OBJECTIVETo measure the immunogenicity of a synthetic peptide of glucosyltransferase (GTF) for designing synthetic peptide-based vaccine of dental caries.

METHODSA fusion 27-mer peptide, containing the conserved regions within catalytic and glucan-binding domains of GTF, was synthesized. Serum antibodies to the synthetic peptide were determined by ELISA method. Inhibitions of both GTF activity and S. mutans adherence were detected for the functions of antisera.

RESULTSThe sequence of fusion peptide vaccine was ANDVDNSNPVVQAEQLYFRANGVQVKG. The spleen weights of immunized mice were heavier than the control ones. Specific antibodies were effectually elicited. The immune sera not only inhibited GTF enzymatic activity but also inhibited the vitro adherence of S. mutans.

CONCLUSIONSThe peptide vaccine which involves antibody-mediated inhibition of the catalytic and the glucan-binding activities of GTF may be valuable for controlling the dental caries.

Amino Acid Sequence ; Animals ; Antibodies ; blood ; Bacterial Adhesion ; drug effects ; Dose-Response Relationship, Drug ; Glucosyltransferases ; antagonists & inhibitors ; genetics ; immunology ; Immune Sera ; pharmacology ; Immunization ; Male ; Mice ; Mice, Inbred BALB C ; Molecular Sequence Data ; Oligopeptides ; administration & dosage ; chemical synthesis ; immunology ; Rats ; Streptococcus mutans ; drug effects ; physiology ; Vaccines, Subunit ; administration & dosage ; chemical synthesis ; immunology

Intestinal epithelial cells (IECs) have been known to produce galactose-alpha1,4-galactose-beta1,4-glucose ceramide (Gb3) that play an important role in the mucosal immune response. The regulation of Gb3 is important to prevent tissue damage causing shiga like toxin. Epigallocatechin-3-gallate (EGCG) has been studied as anti-carcinogenic, anti-oxidant, anti-angiogenic, and anti-viral activities, and anti-diabetic. However, little is known between the expressions of Gb3 on IECs. The aim of this study was to examine the inhibitory effect of EGCG, a major ingredient of green tea, on Gb3 production via mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-kappa B) in the TNF-alpha stimulated human colon epithelial cells, HT29. To investigate how Gb3 is regulated, ceramide glucosyltransferase (CGT), lactosylceramide synthase (GalT2), and Gb3 synthase (GalT6) were analyzed by RT-PCR in HT 29 cells exposed to TNF-alpha in the presence or absence of EGCG. EGCG dose-dependently manner, inhibits TNF-alpha induced Gb3 expression by blocking in both the MAPKs and NF-kappaB pathways in HT29 cells. TNF-alpha enhanced CGT, GalT2 and GalT6 mRNA levels and EGCG suppressed the level of these enzymes enhanced by TNF-alpha treatment.
Apoptosis/drug effects ; Blotting, Western ; Catechin/*analogs & derivatives/pharmacology ; Cell Nucleus/drug effects/metabolism ; Cell Proliferation/drug effects ; Dose-Response Relationship, Drug ; Epithelial Cells/drug effects/metabolism/pathology ; Flow Cytometry ; Galactosyltransferases/genetics ; Gene Expression Regulation, Enzymologic/drug effects ; Glucosyltransferases/genetics ; HT29 Cells ; Humans ; Intestinal Mucosa/drug effects/metabolism/pathology ; Mitogen-Activated Protein Kinases/antagonists & inhibitors/*metabolism ; NF-kappa B/antagonists & inhibitors/*metabolism ; Phosphorylation/drug effects ; Protein Transport/drug effects ; RNA, Messenger/genetics/metabolism ; Research Support, Non-U.S. Gov't ; Reverse Transcriptase Polymerase Chain Reaction ; Trihexosylceramides/*biosynthesis ; Tumor Necrosis Factor-alpha/*pharmacology