XBP1s gene of endoplasmic reticulum stress enhances proliferation and osteogenesis of human periodontal ligament cells.

BACKGROUND: The endoplasmic reticulum stress (ERS) pathway, inositol-requiring enzyme-1 alpha-X-box binding protein-1 (IRE1α-XBP1), has been considered as a critical factor of human periodontal ligament cells (hPDLCs) in proliferation and osteogenesis. This study aimed to explore the effect and mechanism of XBP1s, which was cleaved by IRE1α on the proliferation and osteogenesis of hPDLCs. METHODS: ERS model was induced by tunicamycin (TM); cell proliferation was assessed by CCK-8 assay; pLVX-XBP1s-hPDLCs cell line was established by lentivirus infaction; expression of ERS-related protein including eIF2α, GRP78, ATF4 and XBP1s, autophagy-related P62 and LC3, and apoptosis-related Bcl-2 and Caspase-3 were detected by Western Blot; expression of osteogenic genes was detected by RT-qPCR, and senescence of hPDLCs was explored by ß-galactosidase staining. Furthermore, the interaction between XBP1s and human bone morphogenetic protein 2 (BMP2) was examined by immunofluorescence antibody test (IFAT). RESULTS: The results showed an increase in proliferation of hPDLCs from 0 to 24 h when ERS was induced by TM treatment (P < 0.05). XBP1s overexpression induced hPDLCs proliferation, upgraded autophagy and degraded apoptosis significantly (P < 0.05). In pLVX-XBP1s-hPDLCs, the ratio of senescent cells was markedly decreased after several passages (P < 0.05); After infection with pLVX-BMP2 lentiviral supernatant, IFAT result showed that XBP1s and BMP2 well co-located in the cytoplasm of pLVX-XBP1s-hPDLCs and PERK-ATF4 ERS branch was activated, meanwhile, there were obviously more mineralized nodules and mRNA expression of osteogenesis-related genes was continually up-regulated (P < 0.05). CONCLUSIONS: XBP1s promotes the proliferation via regulating the autophagy and apoptosis, and enhances expression of osteogenic genes in hPDLCs. The mechanisms in this regard need exploring further for periodontal tissue regeneration, functionalization and clinical applications.

Effect of lentivirus-mediated BMP2 from autologous tooth on the proliferative and osteogenic capacity of human periodontal ligament cells.

BACKGROUND AND OBJECTIVE: Periodontitis is a chronic progressive inflammation that invades periodontal supporting tissues, in which periodontal tissue regeneration engineering offers new hope for prevention and treatment, including seed cells, scaffolds, and growth factors. In recent years, scholars have shown that autologous teeth can be used as new bone tissue repair materials for periodontal regeneration and bone tissue repair. The aim of this study was to establish a human periodontal ligament cell line that expresses the human bone morphogenetic protein 2 gene (BMP2) in a stable manner using lentiviral mediation in order to explore the effect of BMP2 from autologous tooth on the proliferative and osteogenic capacity of human periodontal ligament cells (hPDLCs). MATERIALS AND METHODS: Human periodontal ligament cells were cultured, subcultured, and identified, and then homologous recombinant lentivirus plasmid plv-BMP2 was constructed and transfected into the third passage (P3 ) hPDLCs. After that, the effect of BMP2 on its proliferation was detected by CCK-8, at the same time, the osteogenic induction of hPDLCs was carried out at 7, 14, and 21 days, and then the effect of BMP2 on its osteogenic ability was detected by alizarin red staining, alkaline phosphatase activity determination, and the mRNA expression levels of osteogenic-related genes using real-time fluorescence quantitative PCR, including alkaline phosphatase, runt-related transcription factor 2, bone sialoprotein, osteocalcin, osteopontin, and collagen I. Finally, spss26.0 software was used for statistical processing. RESULTS: The results showed that cells transfected with the homologous recombinant lentiviral plasmid pLV-BMP2 had a similar morphology to normal hPDLCs, showing a typical radial arrangement; the cell proliferative capacity of the pLV-BMP2 group as measured by CCK-8 was enhanced compared with the control group and the pLV-puro group (p < .05); alizarin red staining and alkaline phosphatase activity assay showed that the osteogenic ability of pLV-BMP2 was significantly enhanced compared with the control and pLV-puro groups (p < .01), and the findings of real-time fluorescence-based quantitative PCR showed high expression of osteogenic-related genes in pLV-BMP2 group (p < .01). CONCLUSION: In conclusion, a stable periodontal ligament cell line overexpressing BMP2 was successfully established by a lentivirus-mediated method, which proved that BMP2 has a strong ability to promote the proliferation and osteogenesis of hPDLCs, thereby providing an opportunity for the study of periodontal tissue regeneration as well as providing an experimental basis for the application of autologous teeth as a new type of bone repair material for periodontal therapy and even for maxillofacial bone tissue repair.

Mechanism and significance of apoptosis of the immortalized human oral mucosal epithelial cells established by Lentivirus-mediated hTERT.

During the transition from human oral mucosal epithelial cells (HOMEC) to oral squamous cell carcinoma cells (Cal27), the cells must have undergone a precancerous state. To explore the malignant rule of HOMEC, plv-HOMEC was used as a model cell for the precancerous state to investigate plv-HOMEC's apoptosis by comparing human oral mucosal epithelial cells established by Lentivirus-mediated hTERT (plv-HOMEC) with HOMEC and human Cal27. The lentiviral particles overexpressing hTERT were packaged and transfected into primary HOMEC to obtain plv-HOMEC. Expression levels of NF-κB were detected in the cytoplasm and nucleus of Cal27, plv-HOMEC and HOMEC. The level of intracellular reactive oxygen species was measured to verify the endoplasmic reticulum pathway, cytochrome C expression was detected to verify the mitochondrial pathway, and FasL gene expression was detected to verify the death receptor apoptosis pathway. The total expression of NF-κB in plv-HOMEC increased, mainly due to the greater nuclear import of NF-κB, but it was still much lower than Cal27. The endoplasmic reticulum apoptosis pathway of plv-HOMEC was not significantly affected, and there were no significant differences between them and the HOMEC cells; the mitochondrial apoptosis pathway of plv-HOMEC was inhibited, and the expression of Cyt C was very close to that of Cal27, indicating that the characteristics of plv-HOMEC are so familiar with cancer cells; the death receptor apoptosis pathway of plv-HOMEC was also inhibited, and in this apoptotic pathway, plv-HOMEC were more similar to cancer cells than to HOMEC cells. The present data suggest that NF-κB nucleation may increase in the early stage of healthy cells' carcinogenesis, followed by inhibition of the mitochondrial pathway and the death receptor apoptotic pathway.