Expression and splicing of the fibronectin gene in healthy and diseased periodontal tissue

Transcriptome sequencing of gingival biopsies from chronic periodontitis patients reveals novel gene expression and splicing patterns

BACKGROUND

Periodontitis is the most common chronic inflammatory disease caused by complex interaction between the microbial biofilm and host immune responses. In the present study, high-throughput RNA sequencing was utilized to systemically and precisely identify gene expression profiles and alternative splicing.

METHODS

The pooled RNAs of 10 gingival tissues from both healthy and periodontitis patients were analyzed by deep sequencing followed by computational annotation and quantification of mRNA structures.

RESULTS

The differential expression analysis designated 400 up-regulated genes in periodontitis tissues especially in the pathways of defense/immunity protein, receptor, protease, and signaling molecules. The top 10 most up-regulated genes were CSF3, MAFA, CR2, GLDC, SAA1, LBP, MME, MMP3, MME-AS1, and SAA4. The 62 down-regulated genes in periodontitis were mainly cytoskeletal and structural proteins. The top 10 most down-regulated genes were SERPINA12, MT4, H19, KRT2, DSC1, PSORS1C2, KRT27, LCE3C, AQ5, and LCE6A. The differential alternative splicing analysis revealed unique transcription variants in periodontitis tissues. The EDB exon was predominantly included in FN1, while exon 2 was mostly skipped in BCL2A1.

CONCLUSIONS

These findings using RNA sequencing provide novel insights into the pathogenesis mechanism of periodontitis in terms of gene expression and alternative splicing.

Senescent peritoneal mesothelial cells promote ovarian cancer cell adhesion: the role of oxidative stress-induced fibronectin

Adhesion of ovarian cancer cells to the peritoneal mesothelium is a key step in the malignant progression of the disease. In an in vitro study, we showed that the adherence of ovarian cancer cells (of the OVCAR-3, SKOV-3, and A2780 cell lines) to senescent human omentum-derived peritoneal mesothelial cells (HOMCs) was greater than to early passage cells. The process was mediated primarily by the increased interaction of the alpha5beta1 integrin on cancer cells with HOMC-associated fibronectin (FN). In comparison with early passage HOMCs, senescent cells exhibited increased FN mRNA expression levels and produced significantly more FN. To assess the effect of senescence-associated oxidative stress on FN release, HOMCs were rendered senescent by exposure to an oxidant, tert-butyl hydroperoxide. Treatment with tert-butyl hydroperoxide resulted in a significant increase in HOMC FN mRNA and protein expression levels. The effect of oxidative stress on FN synthesis was found to be mediated by transforming growth factor-beta1, whose signaling pathway was controlled at upstream and downstream levels by p38 MAPK. The activity of p38 MAPK increased markedly in senescent HOMCs. Treatment of HOMCs with antioxidants significantly attenuated senescence-associated increases in p38 MAPK activity, production of both transforming growth factor-beta1 and FN, and ovarian cancer cell adhesion. These data indicate that oxidative stress that accompanies senescence may increase FN production by HOMCs and thus facilitate binding and dissemination of ovarian cancer cells.

Analysis of interleukin-1β-modulated mRNA gene transcription in human gingival keratinocytes by epithelia-specific cDNA microarrays

BACKGROUND/OBJECTIVES

Proinflammatory cytokines such as interleukin-1beta are known to be synthesized in oral gingivitis and periodontitis and lead to the activation of the transcription factor nuclear factor-kappaB (NF-kappaB). Although numerous effects of interleukin-1beta on mesenchymal cells are known, e.g. up-regulation of intercellular adhesion molecule-1 in endothelial cells, little is known of the effects of interleukin-1beta on oral keratinocytes. The purpose of the present study was to seek interleukin-1beta-mediated alterations in mRNA gene transcription and a putative activation of NF-kappaB in oral gingival keratinocytes.

METHODS

As an in vitro model for gingivitis and periodontitis, immortalized human gingival keratinocytes (IHGK) were stimulated with the proinflammatory cytokine interleukin-1beta. An epithelia-specific cDNA microarray was used to analyze mRNA expression profiles from IHGK cells treated with 200 units interleukin-1beta/ml for 3, 6, 9, 12, and 24 h. Indirect immunofluorescence was carried out to detect NF-kappaB in IHGK following interleukin-1beta treatment.

RESULTS

Detailed analysis revealed distinct patterns of time-dependent changes, including genes induced or repressed early (3-6 h) or late (12-24 h) after interleukin-1beta treatment. Differentially expressed genes were involved in (i) cell stress, (ii) DNA repair, (iii) cell cycle and proliferation, (iv) anti-pathogen response, (v) extracellular matrix turnover, and (vi) angiogenesis. A large number of genes were responsive to NF-kappaB and induction was concomitant with nuclear translocation of the p65 RelA subunit of NF-kappaB. Interestingly, many of these genes contain multiple NF-kappaB binding sites in their promoters.

CONCLUSION

Analysis of altered gene expression allows identification of gene networks associated with inflammatory responses. In addition to a number of well-known genes involved in gingivitis and periodontitis, we identified novel candidates that might be associated with the onset and maintenance of an inflammatory disease.

Flow cytometry analysis of guided tissue regeneration-associated human periodontal cells

BACKGROUND

Expanded polytetrafluoroethylene (ePTFE) barrier membranes have been widely used for guided tissue regeneration (GTR) of the human periodontal ligament (PL). However, the precise cellular and molecular events involved in the re-growth of the new tissue are still unclear.

METHODS

Retrieved membranes and the newly-regenerated soft tissue (RT) underlying the membranes were used to examine the cells associated with GTR compared with normal human PL and gingival cells. Flow cytometry (FCM) was used, for the first time, to analyze the spindle-shaped fibroblast-like cells which were adherent to these membranes and the cells which grew out of the RT.

RESULTS

The results showed that the membrane-associated (M) cells had the lowest rate of proliferation and appeared to be larger and more granular than the other types of cell. Moreover, both the M- and RT-derived cells were found to express higher levels of the extracellular matrix (ECM) proteins collagen type 1, fibronectin, tenascin, and decorin. In addition, evidence based on FCM profiles identified distinct sub-populations of GTR cells in which fibronectin expression was markedly up-regulated compared with normal PL cells and which also differed in size and granularity.

CONCLUSIONS

The results of this study show that cells associated with GTR barrier membranes and with the underlying tissue appear to have distinct phenotypic and functional activities consistent with the production of new periodontal connective tissue and periodontal regeneration.

Temporal changes in the expression of platelet-derived growth factor and fibronectin in the uterine epithelium during early pregnancy

In rat uterine epithelium, platelet-derived growth factor (PDGF) and fibronectin (FN) display changes in temporal expression during implantation. PDGF was expressed in the apical epithelium on Day 3, apically, laterally and basally at the time of implantation on Day 6 but was not expressed on Day 7. FN expression was not seen until Day 6, when it was expressed only in the basement membrane. However, this label was markedly increased in the basement membrane on Day 7. We suggest that fibronectin may be upregulated by PDGF in preparation for invasion of the basement membrane by stromal decidual cells and the subsequent attachment of the trophoblast to the maternal extracellular matrix.