Immunolocalization and activity of the MMP-9 and MMP-2 in odontogenic region of the rat incisor tooth after post shortening procedure

MT1-MMP and TIMP-2 are first expressed in the colon glands after a single dose of azoxymethane (AOM)

Tissue inhibitor of metalloproteinase-2 (TIMP-2) and membrane-type 1-matrix metalloproteinase (MT1-MMP) are always expressed during the cancer process. The aim was to identify which regions of the colon mucosa MT1-MMP and TIMP-2 begin to express themselves, as well as to establish their expression in relation to cell proliferation and mucin production. After intraperitoneal injection of 15 mg/kg of azoxymethane (AOM) at 4, 12, and 20 weeks, histological sections of the middle segment of the rat colon mucosa were evaluated by immunohistochemistry for cell proliferation and expression of MT1-MMP and TIMP-2 and histochemistry for mucin. As a result, a single dose of AOM initially increased the intensity of MT1-MMP and TIMP-2 expression in the conjunctive cells and glands, concurrently with alterations in the distribution of the mucin produced in the gland of the large intestine mucosa and cell proliferation. As a result, at 4 and 12 weeks, a single dose of AOM initially stimulated the expression of MT1-MMP and TIMP-2 in the conjunctive cells and glands with greater intensity. Changes in the cell proliferation and distribution of the mucin produced in the large intestine mucosa gland were observed. We conclude that MT1-MMP and TIMP-2 were first and strongly expressed in all cells of the colon glands, concurrently with an increase in cell proliferation and a diffuse dispersion of mucin, indicating the onset of the dysplasia process following a single dosage of AOM.

Effects of a Single Dose of X-Ray Irradiation on MMP-9 Expression and Morphology of the Cerebellum Cortex of Adult Rats

Although radiation is a strategy widely used to inhibit cancer progression, which includes those of the neck and head, there are still few experimental reports on radiation effects in the cerebellum, particularly on the morphology of its cortex layers and on the Matrix metalloproteinases' (MMPs') expression, which, recently, seems to be involved in the progression of some mental disorders. Therefore, in the present study, we evaluated the morphology of the cerebellum close to the expression of MMP-9 from 4 up to 60 days after a 15-Gy X-ray single dose of X-ray irradiation had been applied to the heads of healthy adult male rats. The cerebellum of the control and irradiated groups was submitted for an analysis of cell Purkinje count, nuclear perimeter, and chromatin density using morphometric estimatives obtained from the Feulgen histochemistry reaction. In addition, immunolocalization and estimative for MMP-9 expression were determined in the cerebellar cortex on days 4, 9, 14, 25, and 60 after the irradiation procedure. Results demonstrated that irradiation produced a significant reduction in the total number of Purkinje cells and a reduction in their nuclear perimeter, along with an increase in chromatin condensation and visible nuclear fragmentation, which was also detected in the granular layer. MMP-9 expression was significantly increased on 4, 9, and 14 days, being detected around the Purkinje cells and in parallel fibres at the molecular layer. We conclude that the effects of a single dose of 15-Gy X-ray irradiation in the cerebellum were an increase in MMP-9 expression in the first 2 weeks after irradiation, especially surrounding the Purkinje cells and in the molecular layers, with morphological changes in the Purkinje cell and granular cell layers, suggesting a continuous cell loss throughout the days evaluated after irradiation.

Effects of obesity on the rat incisor enamel and dentine thickness, as well as on the hemimandible shape over generations

Obesity has several effects on the general body metabolism. However, little is known about the impact of obesity on the growth and shape of mineralized tissues like mandibles and teeth, as well as if it effects are passed down from generation to next. Therefore, in this study, we aimed to evaluate, over nine generations using the consanguineous mating (inbreeding), the effect of the obesity condition produced by the reduction in the number of rats per litter during the lactation period on the hemimandible shape, dentine, and enamel of the rat incisor. Litters were reduced to two males and two females after birth, and were consanguinity mated in adulthood for nine generations. For all evaluations performed in this investigation, only males were used. The control group was formed by a non-consanguineous litter containing eight males. The parameters evaluated were food consumption, body weight, Lee Index, and bone density of the hemimandible bone. Incisor enamel and dentine thickness were also evaluated. The hemimandible shape was evaluated using geometric morphometry. The results show a significant and progressive increase in food intake, Lee Index, body weight, hemimandible weight, and enamel thickness, and a decrease in dentine thickness. The linear measurements of the length of the ramus ascending hemimandibular segment were found to be shorter, while its height was increased. In contrast, the geometric morphometry shows that the general hemimandible shape changed over the consanguineous obesity generations. We conclude that over generations, obesity increases and maintains the parameters evaluated with significant changes in hemimandible shape as well as in the dimensions of enamel and dentine of incisors, suggesting that enamel and dentine could be used as phenotype biomarkers to detect changes in tooth and craniofacial development related to obesity effects.

Transcriptome analysis of tongue cancer based on high‑throughput sequencing

Tongue cancer is one of the most common types of cancer, but its molecular etiology and pathogenesis remain unclear. The aim of the present study was to elucidate the pathogenesis of tongue cancer and investigate novel potential diagnostic and therapeutic targets. Four matched pairs of tongue cancer and paracancerous tissues were collected for RNA sequencing (RNA-Seq), and the differentially expressed genes were analyzed. The RNA-Seq data of tongue cancer tissues were further analyzed using bioinformatics and reverse transcription-quantitative PCR analysis. The sequenced reads were quantified and qualified in accordance with the analysis demands. The transcriptomes of the tongue cancer tissues and paired paracancerous tissues were analyzed, and 1,700 upregulated and 2,249 downregulated genes were identified. Gene Ontology analysis uncovered a significant enrichment in the terms associated with extracellular matrix (ECM) organization, cell adhesion and collagen catabolic processes. Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that these differentially expressed genes were mainly enriched in the focal adhesion pathway, ECM-receptor interaction pathway, phosphoinositide 3-kinase (PI3K)-Akt pathway, and cell adhesion molecules. Comprehensive analyses of the gene tree and pathway network revealed that the majority of cell cycle genes were upregulated, while the majority of the genes associated with intracellular response, cell adhesion and cell differentiation were downregulated. The ECM-receptor interaction, focal adhesion kinase (FAK) and PI3K-Akt pathways were closely associated with one another and held key positions in differential signaling pathways. The ECM-receptor, FAK and PI3K-Akt signaling pathways were found to synergistically promote tongue cancer occurrence and progression, and may serve as potential diagnostic and therapeutic targets for this type of cancer.

Effect of interrupted eruption on the enamel organ of the rat incisor

The aim of this study was to investigate the behavior of rat incisor tissues during the inhibition of tooth eruption. Twenty Sprague-Dawley rats were used in this study, and incisor eruption was inhibited by a screw pin. Animals were sacrificed 1, 3, 7 and 14 days after the start of the experiment. Cross-sections at the mesial point of the mandibular first molar and sagittal sections of the mandibular tooth germ area were examined using immunohistochemical and immunofluorescence methods. For morphometric analysis, numbers of TRAP-positive cells were calculated against the total number of cells. In cross-sections from the experimental group, dentin was thickened and pulp tissue was constricted day by day. On days 1, 3 and 7, nestin-positive cells were observed in all odontoblast cell bodies and processes, while on day 14 fewer nestin-positive cells were seen than in the control group. On day 14, the mesial area of the periodontal ligament was constricted and the number of TRAP-positive cells in the mesial area was significantly higher than in the control group. In sagittal sections, enamel formation was found to be increased on days 7 and 14. Furthermore, in the enamel matrix amelogenin was expressed more strongly than in the control group. PCNA-positive cells were significantly increased in cells of the tooth germ compared with the control group. These results suggest that inhibition of tooth eruption accelerates the apical elongation with resorption of the mesial area of the alveolar bone and stimulates cell proliferation with thickened enamel towards the apical end.

Binding of amelogenin to MMP-9 and their co-expression in developing mouse teeth

Amelogenin is the most abundant matrix protein in enamel. Proper amelogenin processing by proteinases is necessary for its biological functions during amelogenesis. Matrix metalloproteinase 9 (MMP-9) is responsible for the turnover of matrix components. The relationship between MMP-9 and amelogenin during tooth development remains unknown. We tested the hypothesis that MMP-9 binds to amelogenin and they are co-expressed in ameloblasts during amelogenesis. We evaluated the distribution of both proteins in the mouse teeth using immunohistochemistry and confocal microscopy. At postnatal day 2, the spatial distribution of amelogenin and MMP-9 was co-localized in preameloblasts, secretory ameloblasts, enamel matrix and odontoblasts. At the late stages of mouse tooth development, expression patterns of amelogenin and MMP-9 were similar to that seen in postnatal day 2. Their co-expression was further confirmed by RT-PCR, Western blot and enzymatic zymography analyses in enamel organ epithelial and odontoblast-like cells. Immunoprecipitation assay revealed that MMP-9 binds to amelogenin. The MMP-9 cleavage sites in amelogenin proteins across species were found using bio-informative software program. Analyses of these data suggest that MMP-9 may be involved in controlling amelogenin processing and enamel formation.

MT1-MMP expression in the odontogenic region of rat incisors undergoing interrupted eruption

MT1-MMP (membrane type matrix metalloproteinase-1) has been considered an important membrane-type matrix metalloproteinase involved in the remodeling process in tissue and organ development, including the processes of the tooth and root growth and dental eruption. Therefore, the aims of this study were to evaluate MT1-MMP expression in the odontogenic region, as well as the eruption rate and morphology of the lower-left rat incisor, where the eruption process was interrupted for 14 days by a steel wire attached from the center of the incisor labial face and braced to the first molar. In the interrupted eruption group, the eruption rate was significantly reduced, producing drastic morphological alterations in the tooth germ and socket area. The MT1-MMP expression was widespread in the dental follicle, in both groups studied (normal and interrupted eruption groups); however a significant decrease in immunostaining was observed in the interrupted eruption group. Results indicate that MT1-MMP may have an important role in the process of dental eruption.