scholarly journals From Osteoclast Differentiation to Osteonecrosis of the Jaw: Molecular and Clinical Insights

2019 ◽  
Vol 20 (19) ◽  
pp. 4925 ◽  
Author(s):  
Anesi ◽  
Generali ◽  
Sandoni ◽  
Pozzi ◽  
Grande
Keyword(s):  
Bone Remodelling ◽  
Osteoclast Differentiation ◽  
Osteonecrosis Of The Jaw ◽  
Pathological State ◽  
Bone Homeostasis ◽  
Related Factors ◽  
Receptor Activator ◽  
Stimulating Factor ◽  
Perfect Space ◽  
Bone Physiology

Bone physiology relies on the delicate balance between resorption and formation of its tissue. Bone resorption depends on a process called osteoclastogenesis in which bone-resorbing cells, i.e., osteoclasts, are produced by the differentiation of more undifferentiated progenitors and precursors. This process is governed by two main factors, monocyte colony-stimulating factor (M-CSF) and receptor activator of NFκB ligand (RANKL). While the former exerts a proliferating effect on progenitors/precursors, the latter triggers a differentiation effect on more mature cells of the same lineage. Bone homeostasis requires a perfect space–time coordination of the involved signals. When osteoclastogenesis is poorly balanced with the differentiation of the bone forming counterparts, i.e., osteoblasts, physiological bone remodelling can turn into a pathological state, causing the systematic disruption of bone tissue which results in osteopenia or osteolysis. Examples of these conditions are represented by osteoporosis, Paget’s disease, bone metastasis, and multiple myeloma. Therefore, drugs targeting osteoclastogenesis, such as bisphosphonates and an anti-RANKL monoclonal antibody, have been developed and are currently used in the treatment of such diseases. Despite their demonstrated therapeutic efficacy, these agents are unfortunately not devoid of side effects. In this regard, a condition called osteonecrosis of the jaw (ONJ) has been recently correlated with anti-resorptive therapy. In this review we will address the involvement of osteoclasts and osteoclast-related factors in the pathogenesis of ONJ. It is to be hoped that a better understanding of the biological mechanisms underlying bone remodelling will help in the design a medical therapeutic approach for ONJ as an alternative to surgical procedures.

scholarly journals Microphthalmia-associated Transcription Factor Interactions with 14-3-3 Modulate Differentiation of Committed Myeloid Precursors

2006 ◽  
Vol 17 (9) ◽  
pp. 3897-3906 ◽  
Author(s):  
Agnieszka Bronisz ◽  
Sudarshana M. Sharma ◽  
Rong Hu ◽  
Jakub Godlewski ◽  
Guri Tzivion ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Target Genes ◽  
Osteoclast Differentiation ◽  
Nuclear Factor Κb ◽  
Amino Acid Residues ◽  
Binding Partner ◽  
Kinase C ◽  
Receptor Activator ◽  
Factor Interactions ◽  
Stimulating Factor

The microphthalmia-associated transcription factor (MITF) is required for terminal osteoclast differentiation and is a target for signaling pathways engaged by colony stimulating factor (CSF)-1 and receptor-activator of nuclear factor-κB ligand (RANKL). Work presented here demonstrates that MITF can shuttle from cytoplasm to nucleus dependent upon RANKL/CSF-1 action. 14-3-3 was identified as a binding partner of MITF in osteoclast precursors, and overexpression of 14-3-3 in a transgenic model resulted in increased cytosolic localization of MITF and decreased expression of MITF target genes. MITF/14-3-3 interaction was phosphorylation dependent, and Ser173 residue, within the minimal interaction region of amino acid residues 141–191, was required. The Cdc25C-associated kinase (C-TAK)1 interacted with an overlapping region of MITF. C-TAK1 increased MITF/14-3-3 complex formation and thus promoted cytoplasmic localization of MITF. C-TAK1 interaction was disrupted by RANKL/CSF-1 treatment. The results indicate that 14-3-3 regulates MITF activity by promoting the cytosolic localization of MITF in the absence of signals required for osteoclast differentiation. This work identifies a mechanism that regulates MITF activity in monocytic precursors that are capable of undergoing different terminal differentiation programs, and it provides a mechanism that allows committed precursors to rapidly respond to signals in the bone microenvironment to promote specifically osteoclast differentiation.

scholarly journals Anti-Müllerian Hormone Negatively Regulates Osteoclast Differentiation by Suppressing the Receptor Activator of Nuclear Factor-κB Ligand Pathway

2021 ◽  
Vol 28 (3) ◽  
pp. 223-230
Author(s):  
Jung Ha Kim ◽  
Yong Ryoul Yang ◽  
Ki-Sun Kwon ◽  
Nacksung Kim
Keyword(s):  
Osteoblast Differentiation ◽  
Bone Cells ◽  
Osteoclast Differentiation ◽  
Nuclear Factor Κb ◽  
Bone Morphogenetic Protein 2 ◽  
Tartrate Resistant Acid Phosphatase ◽  
Nuclear Factor ◽  
Bone Homeostasis ◽  
Alizarin Red ◽  
Receptor Activator

Background: Multiple members of the transforming growth factor-β (TGF-β) superfamily have well-established roles in bone homeostasis. Anti-Müllerian hormone (AMH) is a member of TGF-β superfamily of glycoproteins that is responsible for the regression of fetal Müllerian ducts and the transcription inhibition of gonadal steroidogenic enzymes. However, the involvement of AMH in bone remodeling is unknown. Therefore, we investigated whether AMH has an effect on bone cells as other TGF-β superfamily members do.Methods: To identify the roles of AMH in bone cells, we administered AMH during osteoblast and osteoclast differentiation, cultured the cells, and then stained the cultured cells with Alizarin red and tartrate-resistant acid phosphatase, respectively. We analyzed the expression of osteoblast- or osteoclast-related genes using real-time polymerase chain reaction and western blot.Results: AMH does not affect bone morphogenetic protein 2-mediated osteoblast differentiation but inhibits receptor activator of nuclear factor-κB (NF-κB) ligand-induced osteoclast differentiation. The inhibitory effect of AMH on osteoclast differentiation is mediated by IκB-NF-κB signaling.Conclusions: AMH negatively regulates osteoclast differentiation without affecting osteoblast differentiation.

scholarly journals Cxcl9l and Cxcr3.2 regulate recruitment of osteoclast progenitors to bone matrix in a medaka osteoporosis model

2020 ◽  
Vol 117 (32) ◽  
pp. 19276-19286 ◽  
Author(s):  
Quang Tien Phan ◽  
Wen Hui Tan ◽  
Ranran Liu ◽  
Sudha Sundaram ◽  
Anita Buettner ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Structural Integrity ◽  
Bone Matrix ◽  
Osteoclast Differentiation ◽  
Ectopic Expression ◽  
Live Imaging ◽  
Bone Homeostasis ◽  
Cell Recruitment ◽  
Receptor Activator ◽  
Chemokine Ligand

Bone homeostasis requires continuous remodeling of bone matrix to maintain structural integrity. This involves extensive communication between bone-forming osteoblasts and bone-resorbing osteoclasts to orchestrate balanced progenitor cell recruitment and activation. Only a few mediators controlling progenitor activation are known to date and have been targeted for intervention of bone disorders such as osteoporosis. To identify druggable pathways, we generated a medaka (Oryzias latipes) osteoporosis model, where inducible expression of receptor-activator of nuclear factor kappa-Β ligand (Rankl) leads to ectopic formation of osteoclasts and excessive bone resorption, which can be assessed by live imaging. Here we show that upon Rankl induction, osteoblast progenitors up-regulate expression of the chemokine ligand Cxcl9l. Ectopic expression of Cxcl9l recruitsmpeg1-positive macrophages to bone matrix and triggers their differentiation into osteoclasts. We also demonstrate that the chemokine receptor Cxcr3.2 is expressed in a distinct subset of macrophages in the aorta-gonad-mesonephros (AGM). Live imaging revealed that upon Rankl induction, Cxcr3.2-positive macrophages get activated, migrate to bone matrix, and differentiate into osteoclasts. Importantly, mutations incxcr3.2prevent macrophage recruitment and osteoclast differentiation. Furthermore, Cxcr3.2 inhibition by the chemical antagonists AMG487 and NBI-74330 also reduced osteoclast recruitment and protected bone integrity against osteoporotic insult. Our data identify a mechanism for progenitor recruitment to bone resorption sites and Cxcl9l and Cxcr3.2 as potential druggable regulators of bone homeostasis and osteoporosis.

scholarly journals Zoledronate Enhances Osteocyte-Mediated Osteoclast Differentiation by IL-6/RANKL Axis

2019 ◽  
Vol 20 (6) ◽  
pp. 1467 ◽  
Author(s):  
Hyung Joon Kim ◽  
Ha Jin Kim ◽  
YunJeong Choi ◽  
Moon-Kyoung Bae ◽  
Dae Seok Hwang ◽  
...  
Keyword(s):  
Osteoclast Differentiation ◽  
Clinical Importance ◽  
Osteonecrosis Of The Jaw ◽  
Severe Side Effect ◽  
Signal Transducer ◽  
Rankl Expression ◽  
Receptor Activator ◽  
Subsequent Activation ◽  
Transcription 3 ◽  
Nuclear Factor Kb

Bisphosphonates are one of the most widely used synthetic pyrophosphate analogues for the treatment of bone resorbing diseases such as osteoporosis, multiple myeloma, and bone metastases. Although the therapeutic usefulness of bisphosphonates mainly depends on their anti-osteoclastogenic effect, a severe side-effect of bisphosphonates called bisphosphonate-related osteonecrosis of the jaw (BRONJ) could not be explained by the anti-osteoclastogenic effect of bisphosphonates. In the present study, we have evaluated the changes in osteoclastogenesis- or osteoblastogenesis-supporting activities of osteocytes induced by bisphosphonates. Zoledronate, a nitrogen-containing bisphosphonate, markedly increased both the receptor activator of nuclear factor kB ligand (RANKL) as well as sclerostin in osteocyte-like MLO-Y4 cells, which were functionally revalidated by osteoclast/osteoblast generating activities of the conditioned medium obtained from zoledronate-treated MLO-Y4 cells. Of note, the zoledronate treatment-induced upregulation of the RANKL expression was mediated by autocrine interleukin-6 (IL-6) and subsequent activation of the signal transducer and activator of transcription 3 (STAT3) pathway. These results were evidenced by the blunted RANKL expression in the presence of a Janus activated kinase (JAK2)/STAT3 inhibitor, AG490. Also, the osteoclastogenesis-supporting activity was significantly decreased in zoledronate-treated MLO-Y4 cells in the presence of IL-6 neutralizing IgG compared to that of the control IgG. Thus, our results show previously unanticipated effects of anti-bone resorptive bisphosphonate and suggest a potential clinical importance of osteocytes in BRONJ development.

scholarly journals HDAC2 regulates FoxO1 during RANKL-induced osteoclastogenesis

2016 ◽  
Vol 310 (10) ◽  
pp. C780-C787 ◽  
Author(s):  
Ce Dou ◽  
Nan Li ◽  
Ning Ding ◽  
Chuan Liu ◽  
Xiaochao Yang ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Osteoclast Differentiation ◽  
Nuclear Factor Κb ◽  
Negative Regulator ◽  
Bone Homeostasis ◽  
Akt Activation ◽  
Histone Deacetylase 2 ◽  
Forkhead Box ◽  
Receptor Activator ◽  
And Function

The bone-resorbing osteoclast (OC) is essential for bone homeostasis, yet deregulation of OCs contributes to diseases such as osteoporosis, osteopetrosis, and rheumatoid arthritis. Here we show that histone deacetylase 2 (HDAC2) is a key positive regulator during receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis and bone resorption. Bone marrow macrophages (BMMs) showed increased HDAC2 expression during osteoclastogenesis. HDAC2 overexpression enhanced, whereas HDAC2 deletion suppressed osteoclastogenesis and bone resorption using lentivirus infection. Mechanistically, upon RANKL activation, HDAC2 activated Akt; Akt directly phosphorylates and abrogates Forkhead box protein O1 (FoxO1), which is a negative regulator during osteoclastogenesis through reducing reactive oxygen species. HDAC2 deletion in BMMs resulted in decreased Akt activation and increased FoxO1 activity during osteoclastogenesis. In conclusion, HDAC2 activates Akt thus suppresses FoxO1 transcription results in enhanced osteoclastogenesis. Our data imply the potential value of HDAC2 as a new target in regulating osteoclast differentiation and function.

scholarly journals Osteoclasts and Microgravity

Life ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 207
Author(s):  
John Kelly Smith
Keyword(s):  
Nuclear Factor Kappa B ◽  
Simulated Microgravity ◽  
Osteoclast Differentiation ◽  
Zero Gravity ◽  
Hematopoietic Stem ◽  
Receptor Activator ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
Musculoskeletal Systems ◽  
Stimulating Factor

Astronauts are at risk of losing 1.0% to 1.5% of their bone mass for every month they spend in space despite their adherence to diets and exercise regimens designed to protect their musculoskeletal systems. This loss is the result of microgravity-related impairment of osteocyte and osteoblast function and the consequent upregulation of osteoclast-mediated bone resorption. This review describes the ontogeny of osteoclast hematopoietic stem cells and the contributions macrophage colony stimulating factor, receptor activator of the nuclear factor-kappa B ligand, and the calcineurin pathways make in osteoclast differentiation and provides details of bone formation, the osteoclast cytoskeleton, the immune regulation of osteoclasts, and osteoclast mechanotransduction on Earth, in space, and under conditions of simulated microgravity. The article discusses the need to better understand how osteoclasts are able to function in zero gravity and reviews current and prospective therapies that may be used to treat osteoclast-mediated bone disease.

scholarly journals RANKL/RANK/osteoprotegerin system as novel therapeutic target in the treatment of primary bone tumors and osteolytic metastases

2004 ◽  
Vol 12 (2) ◽  
pp. 112-114 ◽  
Author(s):  
Zlatibor Andjelkovic ◽  
Vuka Katic ◽  
Dragan Mihailovic ◽  
Aleksandar Petrovic ◽  
Ivan Bubanovic
Keyword(s):  
Bone Tumors ◽  
Osteoclast Differentiation ◽  
Treatment Strategies ◽  
Osteoclast Formation ◽  
Skeletal Metastases ◽  
Bone Homeostasis ◽  
Primary Bone Tumors ◽  
Receptor Activator ◽  
Primary Bone ◽  
Nf Kappab

Primary bone tumors and cancers that metastasize to bone require osteoclastic activity to release tumor-supportive growth factors from bone tissue. A number of systemic and locally acting factors are known to influence osteoclast formation, fusion, activation, and survival. Recently, two critical extracellular regulators of osteoclast differentiation and activation have been identified: receptor activator of nuclear factor (NF-kappaB) ligand (RANKL) and osteoprotegerin (OPG). RANKL is a tumor necrosis factor (TNF)-related cytokine that stimulates osteoclast differentiation from hematopoietic precursor cells and activation of mature osteoclasts. RANKL activates its specific receptor, receptor activator of NF- kappaB (RANK), located on osteoclasts, chondrocytes and dendritic cells. Binding of the RANK ligand to its receptor and osteoclastogenesis are prevented by osteoprotegerin, a decoy receptor produced by osteoblasts and marrow stromal cells. The balance between RANKL and OPG is of major importance in bone homeostasis. Disorders of the RANKL/RANK/OPG system have been linked to several human diseases, including primary bone tumors skeletal metastases, and hypercalcemia of malignancy. The discovery and characterization of RANKL, RANK and OPG and subsequent studies have changed the concepts of bone metabolism and may form the basis of innovative therapeutic strategies. Novel treatment strategies for bone tumors are emerging based on blockade of the RANKL/RANK interaction. The advantage of these strategies is their potential to selectively target tumor cells. Combining these new strategies with currently available treatments such as chemotherapy and radiation therapy is under investigation, with promising results.

The Impact of Proinflammatory Cytokynes of Rheumatoid Polyarthritis on the Generalized Loss of Bone Mass

2018 ◽  
Vol 69 (9) ◽  
pp. 2541-2545
Author(s):  
Raluca Barzoi ◽  
Elena Rezus ◽  
Codruta Badescu ◽  
Razan Al Namat ◽  
Manuela Ciocoiu
Keyword(s):  
Rheumatoid Arthritis ◽  
Immune Cells ◽  
Osteoclast Differentiation ◽  
Bone Destruction ◽  
Nuclear Factor ◽  
Receptor Activator ◽  
Level Function ◽  
Rheumatoid Polyarthritis ◽  
The Impact ◽  
Nuclear Factor Kb

There is a bidirectional interaction between most immune cells and osteoblasts, osteoclasts and their precursor cells. The receptor activator of nuclear factor-kB ligand (RANKL)/RANK/osteoprotegerin (OPG) system plays an essential role in the formation of osteoblasts, but it also has implications in osteoclast biology and implicitly on the diseases characterized by bone loss. Proinflammatory cytokines existing at synovial level function as direct or indirect stimulators of osteoclast differentiation, but also of its survival or activity, although some cytokines may also play an antiosteocastogenic role. The fate of bone destruction is determined by the balance between osteoclastogenic and antiosteoclastogenic mediators. Our study has shown that the early initiation of the therapy with anti-TNF and anti-IL6 biological agents, in patients with rheumatoid arthritis, inhibits bone destruction, regardless of the anti-inflammatory activity in patients with rheumatoid arthritis.

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