cAMP-PKA signaling pathway regulates bone resorption mediated by processing of cathepsin K in cultured mouse osteoclasts

Park, Young-Guk; Kim, Young Hun; Kang, Sung Koo; Kim, Cheorl Ho

doi:10.1016/j.intimp.2006.01.005

Cited by 10 publications

(8 citation statements)

References 40 publications

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“…This correlates with the findings of Kajiya et al [23], who found that PKA activators inhibited acid secretion in rat osteoclasts, and that PKA inhibitors protected against calcitonin mediated inhibition of acid secretion. In contrast, it was shown that inhibition of PKA-cAMP signaling reduced bone resorption by mouse osteoclasts [44], however, we could not reproduce these findings using PKA inhibitors in the human system, indicating that different species of osteoclasts utilize different signaling cascades to control bone resorption.…”

Section: Discussioncontrasting

confidence: 71%

Screening of protein kinase inhibitors identifies PKC inhibitors as inhibitors of osteoclastic acid secretion and bone resorption

Sørensen

Karsdal

Dziegiel

et al. 2010

BMC Musculoskelet Disord

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BackgroundBone resorption is initiated by osteoclastic acidification of the resorption lacunae. This process is mediated by secretion of protons through the V-ATPase and chloride through the chloride antiporter ClC-7. To shed light on the intracellular signalling controlling extracellular acidification, we screened a protein kinase inhibitor library in human osteoclasts.MethodsHuman osteoclasts were generated from CD14+ monocytes. The effect of different kinase inhibitors on lysosomal acidification in human osteoclasts was investigated using acridine orange for different incubation times (45 minutes, 4 and 24 hours). The inhibitors were tested in an acid influx assay using microsomes isolated from human osteoclasts. Bone resorption by human osteoclasts on bone slices was measured by calcium release. Cell viability was measured using AlamarBlue.ResultsOf the 51 compounds investigated only few inhibitors were positive in both acidification and resorption assays. Rottlerin, GF109203X, Hypericin and Ro31-8220 inhibited acid influx in microsomes and bone resorption, while Sphingosine and Palmitoyl-DL-carnitine-Cl showed low levels of inhibition. Rottlerin inhibited lysosomal acidification in human osteoclasts potently.ConclusionsIn conclusion, a group of inhibitors all indicated to inhibit PKC reduced acidification in human osteoclasts, and thereby bone resorption, indicating that acid secretion by osteoclasts may be specifically regulated by PKC in osteoclasts.

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Section: Discussioncontrasting

confidence: 71%

Screening of protein kinase inhibitors identifies PKC inhibitors as inhibitors of osteoclastic acid secretion and bone resorption

Sørensen

Karsdal

Dziegiel

et al. 2010

BMC Musculoskelet Disord

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“…Some studies suggest that cAMP formation and PKA activation by PTH activate osteoclastogenesis (12), and that cAMP analogs mimicked the effect of PGE2 in osteoclast differentiation (13)(14)(15)(16). In contrast, others report that PKA activation exerts an inhibitory effect on osteoclastogenesis and root resorption by odontoclasts (17)(18)(19)(20)(21)32). Our results suggest that these divergent results may result from activation of EPAC1 and EPAC2 as well as PKA by cAMP.…”

Section: Discussionmentioning

confidence: 59%

“…Moreover, calcitonin, through cAMP/PKA/EPAC cascades, inhibits osteoclast formation, an effect that is not associated with decreased transcription of genes known to be important for osteoclast progenitor cell differentiation, fusion or function (19). Inhibition of PKA exerts its antiresorptive effects on osteoclasts, in part by reducing lysosomal pools of catalytically active cathepsin K (20) and therefore reducing processing and maturation in osteoclasts. Finally, we have recently reported that adenosine A 2A receptors signal for inhibition of NFκB translocation to the nucleus and inhibit osteoclast differentiation by a mechanism that involves cAMP‐PKA‐ERK1/2 signaling (21).…”

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confidence: 99%

Activation of EPAC1/2 is essential for osteoclast formation by modulating NFκB nuclear translocation and actin cytoskeleton rearrangements

Mediero¹,

Pérez-Aso²,

Cronstein³

2014

FASEB j.

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Bisphosphonates inhibit osteoclast differentiation/function via inhibition of Rap1A isoprenylation. As Rap1 is the effector of exchange protein directly activated by cAMP (EPAC) proteins, we determined the role of EPAC in osteoclast differentiation. We examined osteoclast differentiation as the number of primary murine/human bone-marrow precursors that differentiated into multinucleated TRAP-positive cells in the presence of EPAC-selective stimulus (8-pCTP-2=-O-Me-cAMP, 100 M; 8-pCTP-2=-O-Me-cAMP-AM, 1 M) or inhibitor brefeldin A (BFA), ESI-05, and ESI-09 (10 M each). Rap1 activity was assessed, and signaling events, as well as differentiation in EPAC1/2-knockdown RAW264.7 cells, were studied. Direct EPAC1/2 stimulation significantly increased osteoclast differentiation, whereas EPAC1/2 inhibition diminished differentiation (113؎6%, P<0.05, and 42؎10%, P<0.001, of basal, respectively). Rap1 activation was maximal 15 min after RANKL stimulation (147؎9% of basal, P<0.001), whereas silencing of EPAC1/2 diminished activated Rap1 (43؎13 and 20؎15% of control, P<0.001) and NFkB nuclear translocation. TRAP-staining revealed no osteoclast differentiation in EPAC1/ 2-KO cells. Cathepsin K, NFATc1, and osteopontin mRNA expression decreased in EPAC1/2-KO cells when compared to control. RhoA, cdc42, Rac1, and FAK were activated in an EPAC1/2-dependent manner, and there was diminished cytoskeletal assembly in EPAC1/2-KO cells. In summary, EPAC1 and EPAC2 are critical signaling intermediates in osteoclast differentiation that permit RANKL-stimulated NFkB nuclear translocation and actin rearrangements. Targeting Osteoclasts, multinucleated giant cells derived from myeloid precursors belonging to the monocyte/ macrophage family (1, 2), resorb bone during normal bone remodeling and, by increasing in number and resorptive capacity, mediate pathological bone loss, as well. Osteoclasts adhere to bone and form a sealing zone into which they secrete HCl and proteases, such as collagenases, cathepsin K, and tartrate-resistant acid phosphatase (TRAP), which dissolve the mineral and matrix components of bone (3). Myeloid precursors differentiate into osteoclasts after stimulation by macrophage colony-stimulating factor 1 (M-CSF), which acts via its receptor CSF-1R. After interaction with M-CSF, differentiation and activation of osteoclasts is mediated by a complex network of regulatory factors (systemic hormones and locally produced cytokines) and cell-cell and cell-matrix interactions that are required for transition of the osteoclast precursor into a multinucleated and fully activated osteoclast (4, 5). Among these factors, receptor activator of nuclear factor -B ligand (RANKL) is a critical extracellular regulator of osteoclast differentiation and activation (6 -10). RANKL binds to its receptor, RANK, on the surface of osteoclast precursors (OCPs), resulting in the recruitment of TNF receptor associated factors (TRAFs), which activate nuclear factor B (NFB), c-Fos, phospholipase C␥ (PLC␥), and nuclear factor of

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“…To determine whether the resultant mature osteoclasts in the presence of the compounds are functional or not, we analyzed the levels of cathpsin K, which is an essential enzyme for bone resorption activity of the mature osteoclast [3] , [4] , [12] . Cathepsin K is processed from premature (approximately 40 kDa) to mature form (approximately 29 kDa) during osteoclastogenesis.…”

Section: Resultsmentioning

confidence: 99%

The inhibitors of cyclin-dependent kinases and GSK-3β enhance osteoclastogenesis

Akiba

Mizuta

Kakihara

et al. 2016

Biochemistry and Biophysics Reports

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Osteoclasts are multinucleated cells with bone resorption activity that is crucial for bone remodeling. RANK‐RANKL (receptor activator of nuclear factor κB ligand) signaling has been shown as a main signal pathway for osteoclast differentiation. However, the molecular mechanism and the factors regulating osteoclastogenesis remain to be fully understood. In this study, we performed a chemical genetic screen, and identified a Cdks/GSK-3β (cyclin-dependent kinases/glycogen synthase kinase 3β) inhibitor, kenpaullone, and two Cdks inhibitors, olomoucine and roscovitine, all of which significantly enhance osteoclastogenesis of RAW264.7 cells by upregulating NFATc1 (nuclear factor of activated T cells, cytoplasmic 1) levels. We also determined that the all three compounds increase the number of osteoclast differentiated from murine bone marrow cells. Furthermore, the three inhibitors, especially kenpaullone, promoted maturation of cathepsin K, suggesting that the resorption activity of the resultant osteoclasts is also activated. Our findings indicate that inhibition of GSK-3β and/or Cdks enhance osteoclastogenesis by modulating the RANK–RANKL signaling pathway.

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cAMP-PKA signaling pathway regulates bone resorption mediated by processing of cathepsin K in cultured mouse osteoclasts

Cited by 10 publications

References 40 publications

Screening of protein kinase inhibitors identifies PKC inhibitors as inhibitors of osteoclastic acid secretion and bone resorption

Screening of protein kinase inhibitors identifies PKC inhibitors as inhibitors of osteoclastic acid secretion and bone resorption

Activation of EPAC1/2 is essential for osteoclast formation by modulating NFκB nuclear translocation and actin cytoskeleton rearrangements

The inhibitors of cyclin-dependent kinases and GSK-3β enhance osteoclastogenesis

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