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Objective · To investigate the regulatory effects of inflammatory signaling pathway on the expression of G protein-coupled receptor class C group 5 member A (GPRC5A).Methods· Nuclear factor κB (NF-κB)-driven luciferase mice were intraperitoneally injected with lipopolysaccharide (LPS) to evaluate the activation of NF-κB in lungs.GPRC5A expression in lungs was assessed by Western blotting in the C57BL/6J mice injected with LPS.In vitro tests,human lung tumor cell lines Calu-1 and H322,and human embryonic kidney cell line HEK293T were administered with tumor nccrosis factor α (TNF-α) or transfected with p65 expression plasmid;Western blotting,RT-PCR,luciferase reporter gene experiment and immunofluorescence assay were used to analyze the effect of inflammation on GPRC5A expression.Results · Intraperitoneal injection of LPS induced activation of NF-κB pathway in lung tissues,which suppressed the expression of GPRC5A in mice lungs.In Calu-1 cells,TNF-α treatment greatly suppressed the expression of GPRC5A protein and mRNA.In HEK293T cells,transfection of p65 subunit of NF-κB suppressed the expression of GPRC5A promoter-driven luciferase reporter.The H322 cells transfected with green fluorescent protein-p65 almost did not express GPRC5A.Conclusion · NF-κB pathway acts at the promoter of GPRC5A and suppresses its mRNA and protein expression.
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Objective To determine the impact of fluorine and aluminum,and both action combined on the number of rat osteoclasts and bone resorption cultured in vitro and to explore its mechanisms.Methods The osteoclasts and bone marrow stromal cells (BMSCs) isolated from long bone of new born rats were cultured,respectively,in TC199 medium (containing 10％ fetal bovine serum) with fluoride,aluminum and fluoride combined with aluminum.The osteoclasts were inoculated in 96-well culture plate and ivory slice,BMSCs in 6-well culture plate,and culture medium was changed after 2 hours incubation.The cells were divided into control group,fluoride group,aluminum group and fluoride combined with aluminum group; the doses of sodium fluoride were 0,1.0 × 10-4,0,1.0 × 10-4 mol/L and the doses of aluminum chloride were 0,0,1.0 × 10-5,1.0 × 10-5 mol/L,respectively.Tartrate-resistant acid phosphatase (TRAP) staining positive cells were counted under light microscope after TRAP staining on the 5th day and the pit formed in ivory slices were measured by histomorphometry after staining with toludine blue.The expression of osteoprotegerin(OPG) and receptor activator of nuclear factor kappa-B ligand (RANKL) was detected by real-time fluorescence quantitative PCR in BMSCs after 8 h treatment.Results ① Fluoride,aluminum and the interactive effects of fluoride and aluminum all had impact on the numbers of osteoclasts (F =7.15,6.56 and 7.98,respectively,all P ＜ 0.05).The numbers of osteoclasts in fluoride group,aluminum group and fluoride combined with aluminum group[(136.9 ± 22.99),(135.4 ± 23.5),(163.0 ± 24.4) per well] were higher than that in the control group[(92.5 ± 22.1) per well,all P ＜ 0.05].② Fluoride,aluminum and the interactive effects of fluoride and aluminum all had impact on the resorption pit area on ivory slices(F =10.47,12.64,14.29,respectively,all P ＜ 0.05).The resorption pit area on ivory slices in fluoride group,aluminum group and fluoride combined with aluminum group[(0.242 ± 0.031),(0.293 ± 0.026),(0.333 ± 0.016)mm2 per slice] was higher than that in the control group [(0.088 ± 0.030)mm2 per slice,all P ＜ 0.05].③Fluoride,aluminum and the interactive effects of fluoride and aluminum all had impact on the expression ratios of RANKL/OPG in BMSCs (F =8.15,15.38,23.59,respectively,all P ＜ 0.05).The expression ratios of RANKL/OPG in BMSCs in fluoride group,aluminum group and fluoride combined with aluminum group [(193.98 ± 137.93)％,(326.11 ± 176.78)％,(599.84 ± 275.82)％] were higher than that in the control group[(100.00 ± 56.02)％,all P ＜ 0.05].Conclusions Both fluoride and aluminum can cause increase in the number of osteoclasts in vitro and promote cell differentiation and bone resorption activity,which may be related to increased expression ratio of RANKL/OPG mRNA in BMSCs.The stimulating effects of fluoride on osteoclasts differentiation and bone resorption is enhanced by aluminum.
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Objective To investigate the effect of sodium fluoride(NaF) on proliferation, differentiation and the mRNA expression of osteoprotegerin (OPG) and receptor activator of nuclear factor κβ ligand (RAN KL) of mouse osteoblasts. Methods Osteoblasts were isolated from calvarias of Kunming mice born in 1 - 2 d and cultured. Various concentrations of NaF(0, 10-8, 10-7, 10-6, 10-5, 10-4, 10-3mol/L) were added to the culture medium, the proliferation and activity of alkaline phosphatase(ALP) was determined after 72 h or 120 h. The expression of OPG mRNA and RANKL mRNA was analyzed by semi-quantification RT-PCR. Difference among groups was analyzed by One-Way AN0VA. Difference between two groups was analyzed by LSD-t test. Results There was significant difference in cell proliferation among groups after 72 h(F = 13.806, P < 0.05). Compared with control group(0.434 ± 0.010) , the proliferation was significantly induced in 10-7 - 10-4 mol/L groups treated osteoblasts (0.448 ± 0.010, 0.453 ± 0.013, 0.454 ± 0.016, 0.449 ± 0.018, all P< 0.05), and was significantly suppressed in 10-3 mol/L group(0.401 ± 0.009, P < 0.05). There was statistic difference in the activity of ALP among groups(F = 9.021, P < 0.05). Compared with control group (1.677 ± 0.682), the activity of ALP significantly increased in 10-7 - 10-5 mol/L groups[ (2.447 ± 0.756) × 106, (2603 ± 0.183) × 106, (2.687 ± 0.886) × 106 U/L, P < 0.05 or P < 0.01 ] and significantly decreased in 10-4 mol/L group[ (1.479 ± 0.366) × 106 U/L, P < 0.05 ]. There was significant difference in the expression of OPG mRNA among groups(F = 11.299, P< 0.05). Compared with control group (1.000 ± 0.000), the expression of OPG mRNA was significantly increased in 10-7 - 10-4 mol/L groups( 1.058 ± 0.027, 1.053 ± 0.026, 1.088 ± 0.055, 1.069 ± 0.008, P < 0.05 or P < 0.01) , while significantly decreased in 10-3 mol/L group (0.941 ± 0.029, P< 0.05). There was no difference in RANKL mRNA expression among groups (F= 1.311, P> 0.05). The ratio of RANKL/OPG decreased with increasing doses of fluoride and increased in 10-4, 10-3 mol/L groups, but there was no difference between groups(F = 1.376, P> 0.05). Conclusions A biphasic pattern of proliferation and differentiation has been induced in mouse osteoblasts, which manifests stimulation effect in low doses and suppression in higher doses. Low doses of sodium fluoride suppress differentiation and maturation of osteoblasts by increasing expression of OPG mRNA, while high doses of sodium fluoride enhance differentiation and maturation of osteoblasts by decreasing expression of OPG mRNA.