- Fluoride upregulated 303 miRNAs expression and downregulated 61 miRNAs.
- Fluoride exhibited biphasic effect on osteoclast viability, formation and function.
- Fluoride indicated little effect on expression of RANK protein.
- SB431542 inhibited or aggravated fluoride-regulating osteoclast mode.
- Stimulation of fluoride on Smad3 expression exhibited dose-dependent manner.
Studies that have focused on the role TGFß signaling plays in osteoclast activity are gradually increasing; however, literature is rare in terms of fluorosis. The aim of this study is to observe the role the TßR1/Smad3 pathway plays in fluoride regulating cellsosteoclast-like cells that are under the treatment of TGFß receptor 1 kinase. The RANKL-mediated osteoclast-like cells from RAW264.7 cells were used as osteoclast precursor model. The profile of miRNA expression in fluoride-treated osteoclast-like cells exhibited 303 upregulated miRNAs, 61 downregulated miRNAs, and further drew 37 signaling pathway maps by KEGG and Biocarta pathway enrichment analysis. TGFß and its downstream effectors were included among them. Osteoclast viability, formation and function were detected via MTT method, bone resorption pit and tartrate-resistant acid phosphatase (TRACP) staining, respectively. Results demonstrated that different doses of fluoride exhibited a biphasic effect on osteoclast cell viability, differentiation, formation and function. It indicated that a low dose of fluoride treatment stimulated them, but high dose inhibited them. SB431542 acted as TßR1 kinase inhibitor and blocked viability, formation and function of osteoclast-like cells regulated by fluoride. The expression of the osteoclast marker, RANK, and TßR1/Smad3 at gene and protein level was analyzed under fluoride with and without SB431542 treatment. Fluoride treatment indicated little effect on the RANK protein expression; however it significantly influenced TRACP expression in osteoclast-like cells. The stimulation of fluoride on the expression of Smad3 gene and phosphorylated Smad3 protein exhibited dose-dependent manner. SB431542 significantly impeded phosphorylation of Smad3 protein and TRACP expression in osteoclast-like cells that were exposed to fluoride. Our work demonstrated that TGF? signaling played a key role in fluoride regulating osteoclast differentiation, formation and function. It elucidated that TßR1/Smad3 pathway participated in the mechanism of biphasic modulation of osteoclast mode regulated by fluoride.
Fluorosis increases the risk of postmenopausal osteoporosis by stimulating interferon y
Estrogen deficiency in postmenopausal women frequently activates osteoclasts (OC), accelerates bone resorption, and leads to osteoporosis (OP). Previous studies have demonstrated that interferon y (IFNy) could increase bone resorption and may be involved in postmenopausal OP. Fluorosis also increased the risk of fractures and dental fluorosis, and fluoride may enhance osteoclast formation and
Effect of fluoride and low versus high levels of dietary calcium on mRNA expression of osteoprotegerin and osteoprotegerin ligand in the bone of rats
The ratio of osteoprotegerin ligand (OPGL) to osteoprotegerin (OPG) determines the delicate balance between bone resorption and synthesis. The main objective of the present study is to investigate the possible role of OPGL and OPG in the bone metabolism of rats exposed to fluoride and the protective or aggravating effect
Is the severity of osteosclerosis of fluorosis proportional to the dose of fluoride intake?
Histomorphometric study was made on a series of sections of undecalcified epiphyseal femoral specimens from rats with experimental fluorosis. The results revealed osteosclerosis in Group A (5 ppm) being more severe than that in Group B (25 ppm). With the increase of fluoride dose, the parameters fell down instead of
Experimental fluorosis in rats: NaF induced changes of bone and bone marrow
The results of our experiments suggest that increased doses of NaF cause more extensive osteosclerosis due to the decrease in number and/or activity of osteoclasts. Therefore oateosclerosis is caused primarily, not by increased bone formation but, by the inhibition of bone resorption. This view is supported by the fact that
Short-term chronic fluoride administration and trabecular bone remodeling in beagles: a pilot study
We carried out a pilot project to examine the alterations in trabecular bone remodeling activity of spayed Beagle dams exposed to 0.7 mg/kg body wt/day of sodium fluoride (NaF) for a 6 month period. The results indicated that short-term NaF administration does activate trabecular bone remodeling activity by stimulating the
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Fluoride & Osteocytes
The osteocyte is a type of bone cell which is increasingly believed to play an important role in repairing defects that arise in bone, thereby maintaining the bone’s structural integrity. Because osteocytes are engulfed in fluoride-rich bone mineral and help resorb the bone as part of the remodeling process, they
Fluoride's Effect on Osteoblasts (Bone-Forming Cells)
As noted by the National Research Council, "[p]erhaps the single clearest effect of fluoride on the skeleton is its stimulation of osteoblast proliferation." (NRC 2006). Osteoblasts are bone-forming cells. "Stimulatory effects of fluoride on osteoblasts result in formation of osteoid, which subsequently undergoes mineralization." (Fisher RL, et al. 1989). If the new
Fluoride & Osteoclasts
It is well established that fluoride exposure can increase bone formation by increasing the proliferation of osteoblasts. Less clear is fluoride's impact on bone resorption and the cells (osteoclasts) that resorb bone. Many have assumed that fluoride's main effect on bone resorption and osteoclasts is an inhibitory one (i.e., less
Skeletal Fluorosis: The Misdiagnosis Problem
It is a virtual certainty that there are individuals in the general population unknowingly suffering from some form of skeletal fluorosis as a result of a doctor's failure to consider fluoride as a cause of their symptoms. Proof that this is the case can be found in the following case reports of skeletal fluorosis written by doctors in the U.S. and other western countries. As can be seen, a consistent feature of these reports is that fluorosis patients--even those with crippling skeletal fluorosis--are misdiagnosed for years by multiple teams of doctors who routinely fail to consider fluoride as a possible cause of their disease.
Fluoride & Osteoarthritis
While the osteoarthritic effects that occurred from fluoride exposure were once considered to be limited to those with skeletal fluorosis, recent research shows that fluoride can cause osteoarthritis in the absence of traditionally defined fluorosis. Conventional methods used for detecting skeletal fluorosis, therefore, will fail to detect the full range of people suffering from fluoride-induced osteoarthritis.
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