Regulation of DMT1 on autophagy and apoptosis in osteoblast

Abstract

Iron overload has recently been associated with the changes in the bone microstructure that occur in osteoporosis. However, the effect of iron overload on osteoblasts is unclear. The purpose of this study was to explore the function of divalent metal transporter 1 (DMT1) in the pathological processes of osteoporosis. Osteoblast hFOB1.19 cells were cultured in medium supplemented with different concentrations (0, 50, 100, 200, 300, 400, 500 μmol/L) of ferric ammonium citrate (FAC) as a donor of ferric ions. We used western blotting and immunofluorescence to determine the levels of DMT1 after treatment with FAC. Apoptosis was evaluated by detecting the levels of cleaved caspase 3, BCL2, and BAX with western blotting. Autophagy was evaluated by detecting the levels of LC3 with western blotting and immunofluorescence. Beclin-1 expression was also assessed with western blotting. The autophagy inhibitor 3-methyladenine was used to determine whether autophagy affects the apoptosis induced by FAC. Our results show that FAC increased the levels of DMT1, upregulated the expression of BCL2, and downregulated the apoptosis-related proteins cleaved caspase 3 and BAX. Both LC3I/LC3II levels and beclin-1 were also increased, indicating that FAC increases the accumulation of autophagosomes in hFOB1.19 cells. FAC-induced autophagy was increased by the apoptosis inhibitor 3-MA but was reduced in DMT1 shRNA hFOB1.19 cells. These results suggest that the increased expression of DMT1 induces iron overload and iron overload induces osteoblast autophagy and apoptosis, thus affecting the pathological processes of osteoporosis. Clarifying the mechanisms underlying the effects of DMT1 will allow the identification of novel targets for the prevention and treatment of osteoporosis.

NIPA2 regulates osteoblast function by modulating mitophagy in type 2 diabetes osteoporosis

“…Although large studies have been carried out in the past decade to study the possible pathological mechanism of type 2 diabetes osteoporosis, the main active pathological mechanism is complicated and remains controversial. Recent studies have widely reported that the oxidative stress mediated by divalent metal ions plays a key role in the pathogenesis of osteoporosis [3][4][5] , and we previously confirmed the critical effect of divalent metal ions on type 2 diabetes osteoporosis 6,7 .…”

Divalent Metal Transporter 1 Knock-Down Modulates IL-1β Mediated Pancreatic Beta-Cell Pro-Apoptotic Signaling Pathways through the Autophagic Machinery

“…Further, excess iron-induced DMT1 production is a key player in ferroptotic cell death [ 66 ]. Iron overload by DMT1 induction can promote autophagy and apoptosis in osteoblasts [ 67 ]. Remarkably, DMT1 KD restored autophagy regulators which have a very important protective role in cell survival and death (e.g., SQSTM1-T266, PIK3C3-S243, RNF185-T106, BAG3, DAP, and STING) in IL-1β exposed cells, [ 65 , 68 , 69 ].…”

Adverse Impact of Heavy Metals on Bone Cells and Bone Metabolism Dependently and Independently through Anemia

“…[125] Furthermore, the overexpression of divalent metal transporter 1 (DMT-1) in osteoblasts induced autophagy and apoptosis in osteoblasts, thus promoting OP, by inducing cellular iron overload. [126] www.advancedsciencenews.com www.advancedscience.com…”

“…Promoted post-traumatic inflammation and impaired angiogenesis owing to a lack of EPO-inhibited NF-B signaling pathway, EPO-promoted VEGF expression and peripheral endothelial progenitor cells [ 109,110] Iron deficiency Stress erythropoiesis regulated by HRI-eIF2 P-ATF4 signaling pathway [92,94,[113][114][115] Decreased cortical width of femur and tibia, reduced mineralized skeleton, pathological modulation of microarchitecture in the vertebral trabecular bone, and reduced bone formation [ 116,117] Iron overload Iron deposits in bone and low circulating IGF-1 levels, resulting in impaired bone matrix maturation and defective mineralization [ 120] Impaired BMP signaling pathway related to hepcidin expression [ 121,125] Inhibition of osteoblast activity by ROS-activated NF-B signaling pathway [ 123,125] Inhibited osteoblast proliferation, enhanced osteoblast apoptosis and induction of oxidative stress via downregulation of miR-455-3p and upregulation of HDAC2-Nrf2/ARE [ 124] DMT-1 overexpression-mediated autophagy and apoptosis of osteoblasts [ 126] Stimulated differentiation of osteoclasts by ROS-activated NF-B signaling pathway [ 123] epidemiological evidence has proven the increased risks of both degenerative bone diseases and anemia induced by heavy metals. Additionally, anemia-promoted degenerative bone diseases have been established.…”