A Single Amino Acid Substitution in the Intervening Region of 129K Protein of Cucumber Green Mottle Mosaic Virus Resulted in Attenuated Symptoms

Cucumber green mottle mosaic virus (CGMMV), a member of the genus Tobamovirus, is a major threat to economically important cucurbit crops worldwide. An attenuated strain (SH33b) derived from a severe strain (SH) of CGMMV caused a reduction in the viral RNA accumulation and the attenuation of symptoms, and it has been successfully used to protect muskmelon plants against severe strains in Japan. In this study, we compared GFP-induced silencing suppression by the 129K protein and the methyltransferase domain plus intervening region (MTIR) of the 129K protein between the SH and SH33b strains, respectively. As a result, silencing suppression activity (SSA) in the GFP-silenced plants was inhibited efficiently by the MTIR and 129K protein of SH strain, and it coincided with drastically reduced accumulation of GFP-specific small interfering RNAs (siRNAs) but not by that of SH33b strain. Furthermore, analyses of siRNA binding capability (SBC) by the MTIR of 129K protein and 129K protein using electrophoretic mobility shift assay revealed that SBC was found with the MTIR and 129K protein of SH but not with that of SH33b, suggesting that a single amino acid mutation (E to G) in the MTIR is responsible for impaired SSA and SBC of SH33b. These data suggest that a single amino acid substitution in the intervening region of 129K protein of CGMMV resulted in attenuated symptoms by affecting RNA silencing suppression.

Down-regulated genes in mouse dental papillae and pulp

Important factors involved in odontogenesis in mouse dental papillae disappear between the pre- and post-natal stages of development. Therefore, we hypothesized that certain genes involved in odontogenesis in dental papillae were subject to pre-/post-natal down-regulation. Our goal was to identify, by microarray analysis, which genes were down-regulated. Dental papillae were isolated from embryonic 16-day-, 18-day- (E16, E18), and post-natal 3-day-old (P3) murine first mandibular molar germs and analyzed by microarray. The number of down-regulated genes was 2269 between E16 and E18, and 3130 between E18 and P3. Drastic down-regulation (fold change > 10.0) of Adamts4, Aldha1a2, and Lef1 was observed at both E16 and E18, and quantitative RT-PCR revealed a post-natal reduction in their expression (Adamts4, 1/3; Aldh1a2, 1/13; and Lef1, 1/37). These results suggest that down-regulation of these three genes is an important factor in normal odontogenesis in dental papillae.

Expression and function of laminin and integrins on adhesion/migration of primary culture cells derived from rat oral epithelium

BACKGROUND AND OBJECTIVE

It remains controversial whether or not the junctional epithelium cells that are directly attached to teeth migrate on the enamel surface, as those cells are able to adhere firmly to the enamel. The aim of this study was to investigate the expression patterns of laminin gamma(2), integrin beta(4) and integrin alpha(3), and to examine their potential function in cell migration.

MATERIAL AND METHODS

Oral epithelium cells obtained from Sprague-Dawley rats were established in primary culture. We employed a wound-healing assay to characterize the direction of cell extension at the start of cell migration, and observed different localizations of laminin and integrins using immunofluorescence. For functional analyses of integrins, we employed a phosphatidylinositol-3-kinase (PI3K) activator to promote integrin beta(4) function and used P1B5 to inhibit integrin alpha(3) function, and we analyzed the percentage of re-epithelialization as the migration function.

RESULTS

Marked accumulation of laminin gamma(2) was detected in the peripheral cytoplasm of cells adjacent to the wound area, as shown by the results of the migration assay. Integrin beta(4) was detected in the distal cell processes of actively migrating cells, while integrin alpha(3) was found in cell membranes of cells adjacent to the wound area. In the functional analyses, the percentage of re-epithelialization was significantly lower in the PI3K-activator group and in the P1B5-treated group (2.5% and 7.2%, respectively) than in the control group (39.0%) (p < 0.01).

CONCLUSION

The results suggest that laminin gamma(2) is secreted as a foothold for cell migration, that integrin beta(4) participates in cell adhesion and that integrin alpha(3) is involved in cell migration in the primary culture cells.

Effect of the dental adhesive, 4-META/MMA-TBB resin, on adhesion and keratinization of regenerating oral epithelium

BACKGROUND AND OBJECTIVE

The 4-META/MMA-TBB [4-(2-methacryloxyethyl)trimellitic anhydride/methyl methacrylate-tributylborane] resin is widely used as a dental adhesive. It has also been applied in the dressing of gingival wound surfaces following periodontal surgery. However, its effect on the regeneration and/or cell attachment of the oral epithelium remains to be clarified. To evaluate the effect of the resin applied as a wound dressing, we investigated expression of laminin 5, integrin beta(4) and cytokeratin 14 in regenerating oral epithelium treated with this resin following gingivectomy from the viewpoint of cell attachment and differentiation.

MATERIAL AND METHODS

The resin was applied to the entire wound surface in rats after gingival surgery, and regenerating epithelium was examined immediately and at 1, 3, 5, 7 and 14 days later. The resin was removed 2 weeks after application in some animals and tissue further examined at 1, 3, 5 and 7 days later.

RESULTS

Regenerating epithelium under the resin was not keratinized, but became keratinized immediately after removal of the resin. Laminin 5 and integrin beta(4) were immunolocalized in the basal lamina, the internal basal lamina, in marginal cells of the regenerating epithelium and at the resin-regenerating epithelium interface. Cytokeratin 14 localized in the regenerating epithelium underneath the resin, as well as in healthy and regenerated junctional epithelial cells.

CONCLUSION

These results suggest that this resin covers the wound surface and that the regenerating epithelium biologically adheres to the resin during the initial process of its regeneration.

Immunolocalization of laminin and integrin in regenerating junctional epithelium of mice after gingivectomy

BACKGROUND AND OBJECTIVE

The expression patterns of adhesive proteins and extracellular matrix proteins in regenerating gingival epithelium after gingivectomy are unknown. The aim of this study was to examine the expression of laminin 1, laminin gamma(2) (a specific component of laminin 5), integrin beta(4) and integrin alpha(3) in the regenerating gingival epithelium in order to understand the mechanism of wound healing during reconstitution of the sulcular environment.

MATERIAL AND METHODS

The palatal gingivae of the maxillary molars of Institute of Cancer Research mice were excised, and the regenerating tissues were examined 1, 3, 5, 7 and 14 days later. Fresh, non-fixed and non-decalcified frozen sections were prepared and stained using immunofluorescence.

RESULTS

At 1 day post-surgery, intense expression of laminin gamma(2), integrin beta(4) and integrin alpha(3) was distinct in the frontal margin of the regenerating oral epithelium. Laminin gamma(2) was diffusely detected on the root surface and in connective tissues beneath the regenerating oral epithelium at 3 and 5 days. At 7 days, laminin gamma(2) was intermittently recognizable in the internal basal lamina (IBL) close to tooth-facing cells, while laminin gamma(2), integrin beta(4) and integrin alpha(3) were observed in the IBL and in the external basal lamina (EBL) of the regenerating junctional epithelium at 14 days.

CONCLUSION

These results suggest that secretion of laminin 5 in the connective tissue may induce epithelial cell migration, and that binding of laminin 5 to integrin alpha(6)beta(4) and integrin alpha(3)beta(1) in the IBL may provoke cell adhesion and migration of cells facing the tooth on the enamel surface of the regenerating junctional epithelium.

Involvement of laminin and integrins in adhesion and migration of junctional epithelium cells

BACKGROUND AND OBJECTIVE

The junctional epithelium attaches to the enamel surface with hemidesmosomes (of which laminin-5 and integrin-alpha(6)beta(4) are the main components) in the internal basal lamina. Laminin-5 is also involved in cell motility with integrin-alpha(3)beta(1), although their functions have not yet been clarified.The purpose of this study was to determine the functions of those adhesive components between the tooth and the junctional epithelium during cell migration.Because an idea has been proposed that directly attached to tooth cells (DAT cells) may not contribute to cell migration, 5-bromo-2-deoxyuridine staining was performed to confirm cell migration.

MATERIAL AND METHODS

We investigated laminin-gamma(2) (contained only in laminin-5), integrin-beta(4) (involved in cell-extracellular matrix contact) and integrin-alpha(3) (inducing cell migration) in the junctional epithelium, oral gingival epithelium and gingival sulcus epithelium of 6-wk-old ICR mice using laser microdissection, quantitative real-time reverse transcription-polymerase chain reaction, immunofluorescence and 5-bromo-2-deoxyuridine staining.

RESULTS

Laminin and integrins were clearly immuno-localized in the basal lamina of all epithelium. Quantitative analysis of laminin and integrin mRNAs by laser microdissection showed that they were more highly expressed in DAT cells than in basal cells in the oral gingival epithelium. In particular, a 12-fold higher expression of laminin-5 was observed in the junctional epithelium compared with the oral gingival epithelium. 5-Bromo-2-deoxyuridine staining showed rapid coronal migration of DAT cells.

CONCLUSION

These results suggest that the abundant expression of laminin-5 and integrin-alpha(6)beta(4) is involved in the attachment of DAT cells to teeth by hemidesmosomes. Abundant expression of laminin-5 and integrin-alpha(3)beta(1) might assist in DAT cell migration, confirmed by 5-bromo-2-deoxyuridine staining during the turnover of junctional epithelium.

Design and analysis of a nonequilibrium cross-coupled network with a detectable similarity measure

In this paper, a nonequilibrium network which works as a dynamical associative memory is designed. The design is based on a new similarity measure between any stored pattern and a state of the network. Although conventional similarity measures, such as Hamming distance, direction cosine, and so on, are not detectable in a cross-coupled network, the similarity measure proposed in this paper is. The new similarity measure is employed in our design. The network should include the following properties in its output pattern sequence, so that the dynamics of cross-coupled network may be designed: 1) Stored patterns are frequently associated in the dynamical association. 2) The dynamical association is very robust against variation of distributed parameters. Property 1) is achieved by introducing the next two operation modes with inverse N-shaped function into the dynamics of the proposed network. 1) When the state of the network is close enough to a stored pattern at a time step, the state is forced to evolve at the next time step. 2) The state of the network converges to a stored one while it is not close to any stored patterns. By considering these two operation modes, the frequency of associating stored patterns is increased. The authors emphasize the property 2) which is very important for a silicon implementation of the proposed network. In the silicon implementation, parameters of the network must be represented by transistors, resistors, capacitors, and other electric components which exhibit variation in their characteristics. Thus the second property guarantees the easy silicon implementation of the nonequilibrium network proposed in this paper.

Claudin rather than occludin is essential for differentiation in rat incisor odontoblasts

Many morphological and developmental studies have demonstrated the characteristics of tight junctions (TJs) between odontoblasts. However, detailed localization of TJ-associated proteins in odontoblasts and their functions has not yet been clarified. To elucidate the relationship between the establishment of TJ structures and the differentiation of odontoblasts during early dentinogenesis, we studied the expression and localization of constituent proteins of TJs (claudin-1, occludin, ZO-1 and ZO-2) between odontoblasts in rat lower incisors using Western blotting, immunofluorescence and immunoelectron microscopy. When the expression of claudin-1 increases at the distal portion of mature odontoblasts, the TJs form complex networks of strands, and odontoblasts differentiated by developing distal membrane domains and by secreting specific molecules for mineralization. We conclude that the TJs of odontoblasts may play an important role in the differentiation of odontoblasts in rat lower incisors during early dentinogenesis.

Heat stress induces alkaline phosphatase activity and heat shock protein 25 expression in cultured pulp cells

AIM

To investigate the responses of cultured rat pulp cells to heat stress.

METHODOLOGY

Pulp cells were obtained from rat incisors and cultured at 37 degrees C. The cells were cultured at 42 degrees C for 30 min and then cultured at 37 degrees C again. Morphology, alkaline phosphatase (ALP) activity and expression of heat shock protein 25 (HSP25) were investigated at 0, 1, 3, 5, 7, 10 and 14 days following stimulation. As a control, the cells were maintained at 37 degrees C.

RESULTS

Although there were few cells of apoptosis immediately after heat stress, there were mitotic cells from day 1 after heat stress. ALP activity in the heat stress group significantly increased at days 7 and 14 compared with the control group (about 1.7-fold, P < 0.01, Friedman test). HSP25 expression increased in both groups, with HSP25 in the heat stress group being expressed earlier than in the control group, and nuclear localization of HSP25 was observed at days 0 and 1 in heat-stressed cells.

CONCLUSION

These results suggest that heat stress not only induces HSP25 but also enhances ALP activity in pulp cells.

Osteopontin as biomarker in early invasion by squamous cell carcinoma in tongue

BACKGROUND

Osteopontin (OPN) expression in squamous cell carcinoma (SCC) of the tongue has not been clearly elucidated.

METHODS

We selected 46 cases of tongue SCC and investigated the expression of OPN by immunohistochemical staining. The immunopositive reaction and score for each case were semiquantitatively evaluated.

RESULTS

Scores were significantly higher in carcinoma nests than in neighboring normal epithelium or epithelial dysplasia. The OPN was expressed clearly in the cytoplasm of carcinoma cells. In cases of early invasive carcinoma, in particular, expression of OPN showed a remarkable increase at the invasion front compared with the non-invaded regions. However, there was no significant correlation between expression of OPN in the primary tumor nest and lymphatic metastasis, recurrence, or survival rate.

CONCLUSION

This suggests that OPN is a useful biomarker of early invasion by SCC in tongue.

Morphology of Malassez's epithelial rest-like cells in the cementum: transmission electron microscopy, immunohistochemical, and TdT-mediated dUTP-biotin nick end labeling studies

BACKGROUND AND OBJECTIVE

It is known that epithelial islands are embedded in the cementum during tooth root formation, but details of this process remain unknown. The purpose of this study was to investigate the dynamic characteristics of Malassez's epithelial rest cells in the cementum during tooth root formation in pigs in vivo.

MATERIAL AND METHODS

The first molars of 6-mo-old pigs were used in this study. Specimens were decalcified before being embedded in paraffin. Paraffin sections were investigated using TdT-mediated dUTP-biotin nick end labeling (TUNEL), immunohistochemical, and ultrastructural techniques.

RESULTS

Malassez's epithelial rest cells were located close to the root surface at the apical one-third of the periodontal ligament, and epithelial clusters surrounded by distinct lamina cementia were sometimes observed in the cementum. TUNEL-positive cells were detected only in the cementum. Malassez's epithelial rest cells in the periodontal ligament were completely surrounded by basement membranes, but epithelial clusters in the cementum were only intermittently surrounded by such membranes. Cytokeratin-positive cells in the superstratum of the cementum were directly connected by cementocytes and by desmosome-like structures. However, organelles were scarce in the cytokeratin-positive cells in the substratum of the cementum, and the matrix of the cementum was deposited in the cells.

CONCLUSION

These results suggest that the majority of the fragmented Hertwig's root sheath remains in the periodontal ligament and that some cells, which are connected to cementoblasts, are embedded in the cementum and progress to apoptosis.

Responses of rat pulp cells to heat stress in vitro

Although heat stress can cause irritation in the dentin/pulp complex, little is known about the thermotolerance of pulp cells and their response to heat stress. We investigated cultured rat pulp cell responses to heat stress. Cells were subjected to a temperature of 42 degrees C for 30 minutes, and HSPs, alkaline phosphatase activity, and gap-junctional communication were determined at various time points. Although only low levels of HSP70 expression were detected before heat treatment, heat shock markedly induced HSP70 expression, with it gradually increasing at 1 hour after being heated. HSP25, however, showed no dramatic change. Gap junction protein connexin43 rapidly degraded after heat treatment, recovering to normal levels within the following 6 hours. Alkaline phosphatase activity decreased immediately after heat stress, recovering after 1 hour. These results indicate that dental pulp possesses protective factors, including HSPs, and that it can recover viability of intercellular communication and alkaline phosphatase activity after heat stress.

Konjak mosaic virus: the complete nucleotide sequence of the genomic RNA and its comparison with other potyviruses

Konjak mosaic virus (KoMV) belongs to the genus Potyvirus, family Potyviridae. The complete nucleotide sequence of KoMV F isolate (KoMV F) was determined. The genome is 9,544 nucleotides long excluding the 3' terminal poly A tail and encodes a typical potyviral 350-kDa polyprotein of 3,087 amino acids. Phylogenetic analysis using known potyvirus polyproteins shows that KoMV constitutes a branch with yam mosaic virus, close to another branch including Japanese yam mosaic virus, turnip mosaic virus, scallion mosaic virus and lettuce mosaic virus. The 3' terminal 1,842 nucleotides of a different isolate of KoMV, K-2, was also determined, covering the C-terminal 292 amino acids of the nuclear inclusion protein b (NIb), coat protein (CP), and the 3' untranslated region. The amino acid sequences of the KoMV F CP and the nucleotide sequences of the KoMV F 3' untranslated region showed 92.5 and 90.5% identity to the corresponding genes of K-2, 88.7-96.8 and 92.7-94.4% to those of Zantedeschia mosaic virus (ZaMV) isolates, 87.5-89.7% and 85.5-90.3% to those of Japanese hornwort mosaic virus (JHMV) isolates. These results showed that KoMV is a distinct potyvirus and that KoMV, ZaMV, and JHMV are members of the same potyvirus species. Considering that KoMV was the first of these to be described, ZaMV and JHMV may be considered isolates of KoMV.

Correlation between reduction of syndecan-1 expression and clinico-pathological parameters in squamous cell carcinoma of tongue

We examined expression of syndecan-1 in squamous cell carcinoma (SCC) of tongue using immunohistochemistry. Forty-three cases of SCC arising in lateral border of tongue were investigated. From the immunohistochemical staining pattern, the cases were divided into two groups based on expression of syndecan-1 at the supra-peripheral cells of the tumor nest: Group A, completely or mainly positive; Group B, sporadically positive or negative. Most poorly differentiated SCC cases were classified into Group B (81.8%). The number of Group B cases in T1-2 was different from that in T3-4. The number of cases where syndecan-1 expression was reduced was much greater in T3-4, and represented the majority of Group B (86.7%). More than 80% of Grade 4D cases were in Group B (83.3%) based on the Yamamoto-Kohama criteria. These results indicate that reduction of syndecan-1 correlates to histological grade, tumor size and mode of invasion in tongue SCC.

Reduction of osteocalcin expression in aged human dental pulp

AIM

To investigate the expression of osteocalcin mRNA in young and in aged human dental pulp tissue to determine the characteristics of osteocalcin expression.

METHODOLOGY

Human dental pulp tissues of the third molars were obtained from healthy young (17-23 years) and aged (>50 years) subjects, and total RNA was extracted. Osteocalcin mRNA expression was determined by RT-PCR and by quantitative real-time RT-PCR (QRT-PCR). The threshold cycle (Ct) value, which reflects the amount of PCR, was calculated and the difference between the value in young and aged pulp was statistically analysed.

RESULTS

Osteocalcin mRNA was detected in all samples of human dental pulp tissue homogenates by RT-PCR analysis. Osteocalcin mRNA was expressed in young adult dental pulp but was decreased in aged human dental pulp. QRT-PCR analysis also showed a reduced expression of osteocalcin mRNA in aged human pulp. Expression of osteocalcin in young human pulp was significantly higher (about sixfold) than in aged pulp (P<0.01, Mann-Whitney U-test).

CONCLUSION

Reduction of osteocalcin expression may be associated with the loss of viability in human dental pulp tissue, and may be a characteristic of aged human dental pulps.