Abstract

The purpose of this work is to study the action of fluoride on osteoblastic function through knocking down double-stranded RNA-activated protein kinase (PKR)-like ER kinase (PERK) mRNA in OS732 cells (human osteoblast-like cell line). The previous researches had demonstrated that fluoride induced endoplasmic reticulum (ER) stresses in other cells or tissues. PERK as one branch of UPR to combat ER stress played a role in mediating the proliferation and differentiation of osteoblast. The mechanism of skeletal fluorosis by which fluoride regulated osteoblast was not fully defined. We used the real-time PCR and small interfering RNA techniques to determine the expression PERK signaling and osteoblastic and osteoclastic differentiation-related factors and investigated the role of PERK signaling in fluoride-stimulated osteoblastic function. Cells transfected with 50 nM small interfering RNA (siRNA)-PERK showed effectively decreased protein and gene expression of PERK and reduced protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2). Meantime, cells transfected with siRNA significantly decreased the protein level of alkaline phosphatase (ALP) and nuclear factor kappa B ligand (RANKL) in cells under fluoride exposure. It suggested that knockdown of PERK expression hardly stimulated osteoblastic and osteoclastic early differentiation induced by fluoride. Conversely, there were littler effect of siRNA PERK on expression of Runt-related transcription factor 2 (RUNX2) and osteoprotegerin (OPG) in cells, but fluoride exposure markedly stimulated their expression. This study proved that the mechanism underlying fluoride induced osteoblastic and osteoclastic differentiation possible was due to activation of ALP and RANKL mediated by PERK in OS732 cells.

• Related Studies :

  • Fluorosis induces endoplasmic reticulum stress and apoptosis in osteoblasts in vivo

    The present study investigated the effects of fluoride on endoplasmic reticulum (ER) stress (ERS) and osteoblast apoptosis in vivo. Forty-eight Wistar rats were randomly divided into four groups (12/group) and exposed to 0, 50, 100, and 150 mg/L of fluoride in drinking water for 8 weeks, respectively. Peripheral blood samples and bilateral

  • [Effects on expression of osteogenesisgene in the osteoblast with endoplasmic reticulum stress induced by fluoride].

    OBJECTIVE:  To explore the gene expressions of endoplasmic reticulum stress and differentiation in osteoblast treated by excess fluoride. METHODS:  Using primary cultured human osteoblasts for fluorosis model in vitro, apoptosis was inspected by flow cytometer, and RNA was extracted for examination of the unfolded protein response and bone differentiation genes. RESULTS:  Fluoride

  • Role of endoplasmic reticulum stress in aberrant activation of fluoride-treated osteoblasts

    The aberrant activation of osteoblasts in the early stage is one of the critical steps during the pathogenesis of skeletal fluorosis. The endoplasmic reticulum (ER) stresses and unfolded protein response (UPR) are initiated to alleviate the accumulation of unfolded proteins against cell injury. The previous researches had demonstrated that fluoride

  • Neuroligin-3 activates Akt-dependent Nrf2 cascade to protect osteoblasts from oxidative stress.

    Excessive oxidative stress will cause significant injury to osteoblasts, serving as one major pathological mechanism of osteoporosis. Neuroligin-3 (NLGN3) is a postsynaptic cell adhesion protein and is expressed in the bone. We here explored its potential activity against hydrogen peroxide (H2O2)-induced oxidative injury in cultured osteoblasts. In primary murine and

  • Fluoride-induced oxidative stress of osteoblasts and protective effects of baicalein against fluoride toxicity

    The key role of osteoblasts in skeletal fluorosis makes the exploration of the possible mechanisms of the fluoride-induced oxidative stress of osteoblasts of great importance. In this article, the in vitro effects of fluoride on the oxidative stress of osteoblasts are presented. To study the inhibitory effect of baicalein on

• Related FAN Content :

  • 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

  • Fluoride Increases Osteoid Content of Bone

    Fluoride's ability to increase the osteoid content of bone is now undisputed. Osteoid is an unmineralized tissue in bone that, in the normal bone remodeling process, ultimately becomes calcified. As some observers have noted, "[t]he main histological change induced by fluoride is the increase of osteoid volume." (Arnala 1985). One way fluoride

  • 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 & 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.