The Chloride Channel Inhibitor NS3736 Prevents Bone Resorption in Ovariectomized Rats Without Changing Bone Formation

Schaller, Sophie; Henriksen, Kim; Sveigaard, Christina; Heegaard, Anne‐Marie; Hélix, N.; Stahlhut, Martin; Ovejero, Maria C; Johansen, Jens Vilstrup; Solberg, Helene; Andersen, Thomas Levin; Hougaard, D.M.; Berryman, Mark; Shiødt, Christine B; Sørensen, Bjørn H; Lichtenberg, Jens; Christophersen, Palle; Foged, Niels T.; Delaissé, Jean‐Marie; Engsig, Michael T.; Karsdal, Morten A.

doi:10.1359/jbmr.040302

Cited by 142 publications

(88 citation statements)

References 32 publications

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“…As expected, 10,28,31,32 bafilomycin inhibited acidification and resorption as measured by acridine orange and CTX release, respectively (Figure 2). Furthermore NS5818 inhibited both acidification and resorption, although with a lower potency (Figure 2).…”

Section: Chloride Channel and Proton Pump Inhibitors Mimic The Adoii supporting

confidence: 82%

“…We used a metabolically stable analog of NS5818, namely NS3696, that is a close analog of NS3736. 28 Bone resorption was measured by DPYR and was significantly inhibited both by estrogen (P Ͻ 0.001) and NS3696 (P Ͻ 0.001) ( Figure 7A). On the other hand, when bone formation was investigated by assay of serum osteocalcin, estrogen repressed the OVX-induced increase in bone formation to sham levels, in contrast to the chloride channel inhibitor, which had no effect on bone formation ( Figure 7B).…”

Section: Inhibition Of Chloride Channels In Vivo Mimics the Phenotypementioning

confidence: 97%

“…This is in direct alignment with previous results in which a chloride channel inhibitor did not affect bone formation both investigated by osteocalcin measurement and dynamic histomorphometry. 28 Previous studies have clearly indicated osteocalcin to be a valid marker for bone formation and to correlate with dynamic histomorphometry parameters of bone formation. 28,38 -40 Trabecular bone was assessed by peripheral quantitated computed tomography to test whether the inhibition of chloride channels could prevent the bone loss of estrogen deficiency.…”

Section: Inhibition Of Chloride Channels In Vivo Mimics the Phenotypementioning

confidence: 99%

“…The chloride channel inhibitors NS5818 [N- (3,5- 28 which were synthesized at Neurosearch A/S (Ballerup, Denmark). The remaining chemicals were from Sigma-Aldrich (Copenhagen, Denmark) and the culture media were from Life Technologies unless otherwise is specified.…”

Section: Drugs and Chemicalsmentioning

confidence: 99%

“…To obtain a model system for inhibition of acidification, either by inhibition of chloride channels or inhibition of the proton pump, we used the chloride channel inhibitor NS5818, 10 a modified form of NS3736, 28 and the proton pump inhibitor bafilomycin A1 and characterized their effects on acidification and resorption. As expected, 10,28,31,32 bafilomycin inhibited acidification and resorption as measured by acridine orange and CTX release, respectively (Figure 2).…”

Section: Chloride Channel and Proton Pump Inhibitors Mimic The Adoii mentioning

confidence: 99%

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Acidification of the Osteoclastic Resorption Compartment Provides Insight into the Coupling of Bone Formation to Bone Resorption

Karsdal

Henriksen

Sørensen

et al. 2005

The American Journal of Pathology

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139

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Patients with defective osteoclastic acidification have increased numbers of osteoclasts, with decreased resorption, but bone formation that remains unchanged. We demonstrate that osteoclast survival is increased when acidification is impaired, and that impairment of acidification results in inhibition of bone resorption without inhibition of bone formation. We investigated the role of acidification in human osteoclastic resorption and life span in vitro using inhibitors of chloride channels (NS5818/ NS3696), the proton pump (bafilomycin) and cathepsin K. We found that bafilomycin and NS5818 dose dependently inhibited acidification of the osteoclastic resorption compartment and bone resorption. Inhibition of bone resorption by inhibition of acidification, but not cathepsin K inhibition, augmented osteoclast survival, which resulted in a 150 to 300% increase in osteoclasts compared to controls. We investigated the effect of inhibition of osteoclastic acidification in vivo by using the rat ovariectomy model with twice daily oral dosing of NS3696 at 50 mg/kg for 6 weeks. We observed a 60% decrease in resorption (DPYR), increased tartrate-resistant acid phosphatase levels, and no effect on bone formation evaluated by osteocalcin. We speculate that attenuated acidification inhibits dissolution of the inorganic phase of bone and results in an increased number of nonresorbing osteoclasts that are responsible for the coupling to normal bone formation. Thus, we suggest that acidification is essential for normal bone remodeling and that attenuated acidification leads to uncoupling with decreased bone resorption and unaffected bone formation. The coupling process is understood as a bone formation response that is the consequence of bone resorption, with an amount of bone formed that is equal to that resorbed. 1,2 Uncoupling occurs when the balance between formation and resorption is disturbed, which might lead to either osteopetrosis or osteoporosis. 3,4 Although it has long been appreciated that bone formation is tightly coupled to bone resorption in normal adult bone turnover, 5,6 this coupling can be dissociated in some circumstances, for example during skeletal growth and in some but not all osteopetrotic mutations.Bone consists of two phases, the organic phase, which contains proteins such as collagen type I, and the inorganic phase, which consists of crystallized calcium phosphate. Dissolution of the inorganic phase of bone under the osteoclast attached to the bone surface is a prerequisite for degradation of the organic phase, and is mediated by acidification of the resorption compartment. The decrease in pH necessary to dissolve the inorganic phase is mediated by an active transport of protons over the ruffled border membrane, which is driven by an osteoclastic Vtype H ϩ ATPase. 7,8 At the same time a passive transport of chloride through chloride channels preserves the electroneutrality, 9 and is mediated by the chloride channel ClC-7. 10,11 Degradation of the organic phase of bone is for the major part mediated b...

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Section: Chloride Channel and Proton Pump Inhibitors Mimic The Adoii supporting

confidence: 82%

Section: Inhibition Of Chloride Channels In Vivo Mimics the Phenotypementioning

confidence: 97%

Section: Inhibition Of Chloride Channels In Vivo Mimics the Phenotypementioning

confidence: 99%

Section: Drugs and Chemicalsmentioning

confidence: 99%

Section: Chloride Channel and Proton Pump Inhibitors Mimic The Adoii mentioning

confidence: 99%

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Acidification of the Osteoclastic Resorption Compartment Provides Insight into the Coupling of Bone Formation to Bone Resorption

Karsdal

Henriksen

Sørensen

et al. 2005

The American Journal of Pathology

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139

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Generation and characterization of mice with null mutation of the chloride intracellular channel 1 gene

Qiu

Jiang

Matthaei

et al. 2010

genesis

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Osteoclast‐specific Dicer gene deficiency suppresses osteoclastic bone resorption

Mizoguchi

Izu

Hayata

et al. 2009

J of Cellular Biochemistry

161

136

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Osteoclasts are unique cells that resorb bone, and are involved in not only bone remodeling but also pathological bone loss such as osteoporosis and rheumatoid arthritis. The regulation of osteoclasts is based on a number of molecules but full details of these molecules have not yet been understood. MicroRNAs are produced by Dicer cleavage an emerging regulatory system for cell and tissue function. Here, we examine the effects of Dicer deficiency in osteoclasts on osteoclastic activity and bone mass in vivo. We specifically knocked out Dicer in osteoclasts by crossing Dicer flox mice with cathepsin K-Cre knock-in mice. Dicer deficiency in osteoclasts decreased the number of osteoclasts (N.Oc/BS) and osteoclast surface (Oc.S/BS) in vivo. Intrinsically, Dicer deficiency in osteoclasts suppressed the levels of TRAP positive multinucleated cell development in culture and also reduced NFATc1 and TRAP gene expression. MicroRNA analysis indicated that expression of miR-155 was suppressed by RANKL treatment in Dicer deficient cells. Dicer deficiency in osteoclasts suppressed osteoblastic activity in vivo including mineral apposition rate (MAR) and bone formation rate (BFR) and also suppressed expression of genes encoding type I collagen, osteocalcin, Runx2, and Efnb2 in vivo. Dicer deficiency in osteoclasts increased the levels of bone mass indicating that the Dicer deficiency-induced osteoclastic suppression was dominant over Dicer deficiency-induced osteoblastic suppression. On the other hand, conditional Dicer deletion in osteoblasts by using 2.3 kb type I collagen-Cre did not affect bone mass. These results indicate that Dicer in osteoclasts controls activity of bone resorption in vivo.

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The Chloride Channel Inhibitor NS3736 Prevents Bone Resorption in Ovariectomized Rats Without Changing Bone Formation

Cited by 142 publications

References 32 publications

Acidification of the Osteoclastic Resorption Compartment Provides Insight into the Coupling of Bone Formation to Bone Resorption

Acidification of the Osteoclastic Resorption Compartment Provides Insight into the Coupling of Bone Formation to Bone Resorption

Generation and characterization of mice with null mutation of the chloride intracellular channel 1 gene

Osteoclast‐specific Dicer gene deficiency suppresses osteoclastic bone resorption

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