p120 regulates E-cadherin expression in nasal epithelial cells in chronic rhinosinusitis.

BACKGROUND: The epithelial barrier plays an important role in the regulation of immune homeostasis. The effect of the immune environment on E-cadherin has been demonstrated in previous studies. This discovery prompted new research on the targeting mechanism of E-cadherin in chronic rhinosinusitis (CRS). METHODS: E-cadherin and p120 expression was determined by quantitative RT-PCR, and western blot. The interaction between E-cadherin and p120 was assessed by immunofluorescence staining and coimmunoprecipitation assays. Human nasal epithelial cells (HNECs) were cultured with submerged methods and transfected with p120-specific small interfering RNA. In other experiments, HNECs differentiated with the air-liquid interface (ALI) method were stimulated with various cytokines and Toll-like receptor (TLR) agonists. The barrier properties of differentiated HNECs were determined by assessing fluorescent dextran permeability. RESULTS: E-cadherin and p120 expression was decreased in HNECs from patients with CRS, and the p120 protein expression level was positively correlated with that of E-cadherin. Two isoforms of p120 (p120-1 and p120-3) were expressed in HNECs, with p120-3 being the main isoform. Knocking down p120 in HNECs cultured under submerged conditions significantly reduced the E-cadherin protein expression. The Rac1 inhibitor NSC23766 reversed the protein expression of E-cadherin in p120 knockdown experiments. Inflammatory mediators, including IL-4, TNF-α, TGF- ß, LPS and IFN-Î, reduced E-cadherin and p120 protein expression and increased paracellular permeability. Dexamethasone abolished the downregulation of E-cadherin and p120 caused by inflammatory mediators. CONCLUSIONS: p120 is involved in regulating E-cadherin protein expression in CRS. Dexamethasone may alleviate the reduction in E-cadherin and p120 protein expression caused by inflammatory mediators.

Downregulation of GNAS inhibits osteogenesis of bone marrow mesenchymal stem cells and promotes osteoporosis through the Wnt pathway.

OBJECTIVE: This study aims to explore the role of GNAS in accelerating the progression of osteoporosis by inhibiting osteogenesis of BMSCs by the Wnt pathway. PATIENTS AND METHODS: GNAS levels in OP tissues and BMSCs undergoing osteogenesis for different time points were detected. Regulatory effects of GNAS on osteogenesis-related gene expressions, ALP activity, capability of mineralization, and activation of the Wnt pathway in BMSCs were assessed through a series of functional experiments. At last, rescue experiments were performed to further verify the significance of the Wnt pathway during GNAS-mediated osteogenesis development. RESULTS: GNAS was downregulated in OP tissues relative to normal bone tissues. With the prolongation of osteogenesis, GNAS level gradually increased in BMSCs. Knockdown of GNAS downregulated expression levels of ALP and RUNX2, and attenuated ALP activity and capability of mineralization in BMSCs. GNAS was able to activate the Wnt pathway in BMSCs. Notably, overexpression of Wnt3a could reverse the regulatory effects of GNAS on osteogenesis-related gene expressions, ALP activity, and capability of mineralization in BMSCs. CONCLUSIONS: Downregulation of GNAS suppresses osteogenesis of BMSCs through the Wnt pathway, thus aggravating the progression of osteoporosis.

[Trichloroethylene-induced abnormal methylation on promoter region of SET in hepatic L-02 cells].

Objective: To explore the trichloroethylene-induced alteration of methylation on the promoter region of SET and related mechanisms in hepatic L-02 cells. Methods: L-02 cells were treated with different concentrations of TCE(0 mmol/L, 1 mmol/L, 2 mmol/L, 4 mmol/L, 8 mmol/L) for 24 h. The genomic DNA were then extracted and modified by bisulfite sodium. The DNA methylation was then analyzed using bisulfite sequencing PCR (BSP). Results: The overall methylation on promoter region of SET was decreased along with the increased concentrations of TCE in hepatic L-02 cells. Moreover, 73 CpG islands were found abnormally altered, among which 9 were predicted in transcriptional factor binding regions. Conclusion: The decreased levels of CpG islands in the transcriptional factor binding region may contribute to the elevation of SET in TCE-induced hepatotoxicity.

[An investigation of trichloroethylene-induced effects on histone methylation in L-02 hepatic cells].

Objective: To further explore TCE-induced hepatotoxicity and its mechanisms by identification of trichloroethylene (TCE) induced abnormal histone methylation in human liver cells. Methods: L-02 cells were treated with 0 and 8 mmol/L TCE for 24 h. Histones were extracted by acid. Liquid chromatography electrospray ionization tandem mass spectrometry (ESI-LC-MS/MS) were used to identify and quantify TCE related histone methylations. TCE induced abnormal methylation of H3K79 me2 and H3K79 me3 were validated by Western blot analysis. The further analysis of the function of histone abnormal methylation modifications were done by single cell gel electrophoresis (SCGE) and Western blot analysis of p53 and ɤH2AX. Results: After treatment with TCE for 24 h in L-02 cells, the 36 TCE related histone methylation sites in 28 peptide segments were identified by MS. After treatment with TCE in concentrations of 0 and 8.0 mmol/L in L-02 cells for 24 h, the relative expression level of histone H3K79 me3 were 1.00±0.06, 0.70±0.09 (t=15.01, P=0.015); the relative expression level of histone H3K79 me2 were 1.00±0.05, 0.74±0.07 (t=16.69, P=0.018); the Olive Tail Moment about DNA damage were 1.46±0.28, 3.12± 0.68 (t=15.22, P=0.018); the relative expression levels of p53 were 1.00±0.04, 1.24±0.04 (t=18.71, P= 0.012); and the relative expression levels of ɤH2AX were 1.00 ± 0.03, 1.56 ± 0.11 (t=8.32, P=0 045). Conclusion: TCE can induce changes in the relative expression level of H3K79 me2 and H3K79 me3 in L-02 cell, and induce DNA damage, suggesting that TCE may induce changes in the relative expression level of H3K79 me2 and H3K79 me3 by DNA damage.

Overexpressed hPTTG1 promotes breast cancer cell invasion and metastasis by regulating GEF-H1/RhoA signalling.

Human pituitary tumour-transforming gene 1 (hPTTG1) is an oncogenic transcription factor that is overexpressed in many tumour types, especially tumours with metastatic abilities. However, how hPTTG1 overexpression drives metastasis is not yet clear. As a transcription factor, hPTTG1 may promote metastasis by activating target genes that are involved in the metastatic process. Here, we showed that Rho guanine nucleotide exchange factor-H1 (GEF-H1) was transcriptionally activated by hPTTG1, thereby promoting breast cancer metastasis. Luciferase reporter analyses and chromatin immunoprecipitation (ChIP) assays showed that hPTTG1 directly bound and activated the GEF-H1 gene promoter. In this study, RNA interference-mediated knockdown of hPTTG1 in highly metastatic breast tumour cells decreased GEF-H1 expression and RhoA activation, thereby reducing cell motility and invasion, and interfering with cytoskeletal remodelling in vitro, and impairing the tumour metastasis in vivo. The restoration of GEF-H1 expression in hPTTG1-knockdown cells rescued the hPTTG1-knockdown effects on cytoskeletal changes in vitro and tumour metastasis in vivo. Conversely, ectopic expression of hPTTG1 in non-metastatic breast tumour cells induced cytoskeletal rearrangements, and allowed these cells to metastasise in a mouse model by orthotopic implantation. In human tumour samples, hPTTG1 expression was also correlated to GEF-H1 expression in aggressive breast carcinoma. Altogether, these findings definitively establish a role for hPTTG1 in activating the GEF-H1/RhoA pathway as a newly identified mechanism in breast cancer metastasis.

Fc and C3b receptors on pulmonary endothelial cells: induction by injury.

Receptors for the activated third component of complement and for the Fc portion of immunoglobulin G are not expressed by apparently normal bovine pulmonary endothelial cells, but are expressed when the cells are exposed to white cell lysates or are infected with influenza or cytomegalovirus. The unmasking of these latent receptors may contribute to the pulmonary inflammatory response characteristic of, for example, anaphylaxis and to those lung diseases characterized by the deposition of immune complexes.