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Journal of Cellular and Molecular... Dec 2023Tumour necrosis factor-α (TNF-α) is a cytokine involved in systemic inflammation. TNF-α slows down osteogenic differentiation, which may contribute to poor bone...
Tumour necrosis factor-α (TNF-α) is a cytokine involved in systemic inflammation. TNF-α slows down osteogenic differentiation, which may contribute to poor bone development in the inflammatory microenvironment. TNF-α inhibits osteogenic differentiation by activating the JAK-STAT3 pathway, of which Signal transducer and activator of transcription 3 (STAT3)-interacting protein 1 (StIP1, also known as elongator complex protein 2, ELP2) is a key protein in the JAK-STAT3 pathway. We investigated whether and how ELP2 activation mediates the TNF-α-induced pyroptosis during osteoblastic differentiation. Using in vitro cell cultures of preosteoblastic MC3T3-E1 cells, we found that TNF-α exposure causes cell pyroptosis in an inflammatory microenvironment during osteoblastic differentiation. Bioinformatics, protein docking model and co-immunoprecipitation analysis revealed an association between ELP2, STAT3 and NLRP3. Forced ELP2 expression promoted MC3T3-E1 cells pyroptosis, with an increase in the expression of STAT3, NLRP3 inflammasome, GSDMD/GSDME, osteoblast marker genes, and the activity of alkaline phosphatase. In contrast, ELP2 silencing ameliorated MC3T3-E1 cells pyroptosis, and osteogenic differentiation, especially after TNF-α stimulation. The TNF-α-induced cells pyroptosis during osteoblastic differentiation was therefore mediated by ELP2. These results suggest that ELP2 is upregulated at the pyroptosis of MC3T3-E1 cells and inhibits osteogenic differentiation in response to TNF-α through NLRP3-GSDMD/GSDME activation.
Topics: Cell Differentiation; NLR Family, Pyrin Domain-Containing 3 Protein; Osteoblasts; Osteogenesis; Pyroptosis; Tumor Necrosis Factor-alpha; Animals; Mice
PubMed: 37830762
DOI: 10.1111/jcmm.17994 -
International Journal of Nanomedicine 2023In chronic periodontitis, exosomes transport various informative substances between osteoclasts and osteoblasts in alveolar bone. Herein, we aimed to investigate the...
BACKGROUND
In chronic periodontitis, exosomes transport various informative substances between osteoclasts and osteoblasts in alveolar bone. Herein, we aimed to investigate the effect of exosomal micro-ribonucleic acid (miRNA/miR)-5134-5p derived from osteoclasts on osteoblastic proliferation and differentiation and the development of periodontitis in vivo and in vitro.
METHODS
The effects of OC-Exos on the proliferation and differentiation of osteoblasts were identified by Real-time quantitative reverse polymerase chain reaction (qRT-PCR), Western blot(WB), alkaline phosphatase(ALP) staining, etc. Exosomal miRNA expression was analyzed by sequencing. The sites of miRNA action were predicted through TargetScan and tested by double luciferase assay. After transfecting miR-5134-5p mimic/inhibitor into osteoblasts, we measured the proliferation and differentiation of osteoblasts by ALP staining and WB, etc. Furthermore, OC-Exos were injected into the gingival sulcus at the ligation site. Inflammation was observed by Hematoxylin-eosin (H&E) staining, the expression of inflammatory factors were detected by qRT-PCR, the resorption of alveolar bone was observed by Micro CT.
RESULTS
Osteoblastic proliferation and differentiation were negatively regulated by OC-Exos in vitro. miRNA sequencing analysis revealed that miR-5134-5p expression was significantly elevated in OC-Exos, which also increased in osteoblasts following OC-Exo intervention. The dual-luciferase assay revealed that miR-5134-5p and Janus kinase 2 (JAK2) had binding sites. miR-5134-5p-mimics could upregulate miR-5134-5p expression in osteoblasts while downregulating Runt-related transcription factor 2(Runx2), phosphorylated-JAK2 (p-JAK2), and phosphorylated-signal transducer and activator of transcription 3 (p-STAT3) expression and inhibited osteogenic differentiation. However, miR-5134-5p-inhibitor had the opposite effect. In vivo, the OC-Exo group demonstrated morphological disruption of periodontal tissue, massive inflammatory cell infiltration, upregulation of inflammatory factors mRNA expression, a significant decrease in BV/TV, and an increase in the cementoenamel junction and alveolar bone crest distance.
CONCLUSION
Osteoclast-derived exosomal miR-5134-5p inhibits osteoblastic proliferation and differentiation via the JAK2/STAT3 pathway. OC-Exos exacerbate periodontal tissue inflammation and accelerate alveolar bone resorption in mice with experimental periodontitis.
Topics: Mice; Animals; Osteogenesis; Osteoclasts; Janus Kinase 2; STAT3 Transcription Factor; MicroRNAs; Cell Differentiation; Osteoblasts; Periodontitis; Inflammation; Homeostasis; Luciferases
PubMed: 37441084
DOI: 10.2147/IJN.S413692 -
Phytotherapy Research : PTR Oct 2023Icariin, a flavonoid glycoside derived from Epimedium brevicornum Maxim, exerts bone protective effects via estrogen receptors (ERs). This study aimed to investigate the...
Icariin, a flavonoid glycoside derived from Epimedium brevicornum Maxim, exerts bone protective effects via estrogen receptors (ERs). This study aimed to investigate the role of ER-α66, ER-α36, and GPER in bone metabolism in osteoblasts following treatment with icariin. Human osteoblastic MG-63 cells and osteoblast-specific ER-α66 knockout mice were employed. The ERs crosstalk in the estrogenic action of icariin was evaluated in ER-α66-negative human embryonic kidney HEK293 cells. Icariin, like E2, regulated ER-α36 and GPER protein expression in osteoblasts by downregulating them and upregulating ER-α66. ER-α36 and GPER suppressed the actions of icariin and E2 in bone metabolism. However, the in vivo administration of E2 (2 mg/kg/day) or icariin (300 mg/kg/day) restored bone conditions in KO osteoblasts. ER-α36 and GPER expression increased significantly and rapidly activated and translocated in KO osteoblasts after treatment with E2 or icariin. ER-α36 overexpression in KO osteoblasts further promoted the OPG/RANKL ratio induced by E2 or icariin treatment. This study showed icariin and E2 elicit rapid estrogenic responses in bone through recruiting ER-α66, ER-α36, and GPER. Notably, in osteoblasts lacking ER-α66, ER-α36, and GPER mediate the estrogenic effects of icariin and E2, while in intact osteoblasts, ER-α36 and GPER act as negative regulators of ER-α66.
Topics: Animals; Mice; Humans; Receptors, Estrogen; Phytoestrogens; Estrogen Receptor alpha; HEK293 Cells; Flavonoids; Osteoblasts
PubMed: 37421324
DOI: 10.1002/ptr.7939 -
Cell Death & Disease Feb 2024Histone methylation plays a crucial role in various cellular processes. We previously reported the in vitro function of histone lysine demethylase 7 A (KDM7A) in...
Histone methylation plays a crucial role in various cellular processes. We previously reported the in vitro function of histone lysine demethylase 7 A (KDM7A) in osteoblast and adipocyte differentiation. The current study was undertaken to investigate the physiological role of KDM7A in bone homeostasis and elucidate the underlying mechanisms. A conditional strategy was employed to delete the Kdm7a gene specifically in osterix-expressing osteoprogenitor cells in mice. The resulting mutant mice exhibited a significant increase in cancellous bone mass, accompanied by an increase in osteoblasts and bone formation, as well as a reduction in osteoclasts, marrow adipocytes and bone resorption. The bone marrow stromal cells (BMSCs) and calvarial pre-osteoblastic cells derived from the mutant mice exhibited enhanced osteogenic differentiation and suppressed adipogenic differentiation. Additionally, osteoclastic precursor cells from the mutant mice exhibited impaired osteoclast differentiation. Co-culturing BMSCs from the mutant mice with wild-type osteoclast precursor cells resulted in the inhibition of osteoclast differentiation. Mechanistic investigation revealed that KDM7A was able to upregulate the expression of fibroblast activation protein α (FAP) and receptor activator of nuclear factor κB ligand (RANKL) in BMSCs through removing repressive di-methylation marks of H3K9 and H3K27 from Fap and Rankl promoters. Moreover, recombinant FAP attenuated the dysregulation of osteoblast and adipocyte differentiation in BMSCs from Kdm7a deficient mice. Finally, Kdm7a deficiency prevented ovariectomy-induced bone loss in mice. This study establish the role of KDM7A in bone homeostasis through its epigenetic regulation of osteoblast and osteoclast differentiation. Consequently, inhibiting KDM7A may prove beneficial in ameliorating osteoporosis. KDM7A suppresses osteoblast differentiation and bone formation through. upregulating FAP expression and inactivating canonical Wnt signaling, and conversely promotes osteoclast differentiation and bone resorption through upregulating RANKL expression. These are based on its epigenetic removal of the repressive H3K9me2 and H3K27me2 marks from Fap and Rankl promoters. As a result, the expression of KDM7A in osteoprogenitor cells tends to negatively modulate bone mass.
Topics: Animals; Female; Mice; Bone Resorption; Cell Differentiation; Epigenesis, Genetic; Histone Demethylases; Homeostasis; Osteoblasts; Osteoclasts; Osteogenesis; RANK Ligand; Jumonji Domain-Containing Histone Demethylases
PubMed: 38346941
DOI: 10.1038/s41419-024-06521-z -
Clinical Science (London, England :... Aug 2023Osteoporosis is a metabolic bone disease that affects hundreds of millions of people worldwide and is characterized by excessive loss of bone protein and mineral...
Osteoporosis is a metabolic bone disease that affects hundreds of millions of people worldwide and is characterized by excessive loss of bone protein and mineral content. The incidence and mortality of osteoporosis increase with age, creating a significant medical and economic burden globally. The importance of cholesterol levels has been reported in the development of diseases including osteoporosis. It is important to note that key enzymes and molecules involved in cholesterol homeostasis are closely related to bone formation. Excessive cholesterol may cause osteoporosis, cholesterol and its metabolites affect bone homeostasis by regulating the proliferation and stimulation of osteoblasts and osteoclasts. Therefore, antagonism of elevated cholesterol levels may be a potential strategy to prevent osteoporosis. There is sufficient evidence to support the use of bisphosphonates and statin drugs for osteoporosis in the clinic. Therefore, in view of the aggravation of the aging problem, we summarize the intracellular mechanism of cholesterol homeostasis and its relationship with osteoporosis (including cholesterol and cholesterol oxidation products (COPs) in osteoporosis). Furthermore, the current clinical cholesterol-lowering drugs for osteoporosis were also summarized, as are new and promising therapies (cell-based therapies (e.g., stem cells) and biomaterial-delivered target drug therapies for osteoporosis as well).
Topics: Humans; Osteoporosis; Osteoclasts; Osteoblasts; Bone and Bones; Homeostasis
PubMed: 37553962
DOI: 10.1042/CS20220752 -
Frontiers in Immunology 2024As the world population ages, osteoporosis, the most common disease of bone metabolism, affects more than 200 million people worldwide. The etiology is an imbalance in... (Review)
Review
As the world population ages, osteoporosis, the most common disease of bone metabolism, affects more than 200 million people worldwide. The etiology is an imbalance in bone remodeling process resulting in more significant bone resorption than bone remodeling. With the advent of the osteoimmunology field, the immune system's role in skeletal pathologies is gradually being discovered. The cytokine interferon-gamma (IFN-γ), a member of the interferon family, is an important factor in the etiology and treatment of osteoporosis because it mediates bone remodeling. This review starts with bone remodeling process and includes the cellular and key signaling pathways of bone remodeling. The effects of IFN-γ on osteoblasts, osteoclasts, and bone mass are discussed separately, while the overall effects of IFN-γ on primary and secondary osteoporosis are summarized. The net effect of IFN-γ on bone appears to be highly dependent on the environment, dose, concentration, and stage of cellular differentiation. This review focuses on the mechanisms of bone remodeling and bone immunology, with a comprehensive discussion of the relationship between IFN-γ and osteoporosis. Finding the paradoxical balance of IFN-γ in bone immunology and exploring the potential of its clinical application provide new ideas for the clinical treatment of osteoporosis and drug development.
Topics: Humans; Bone Remodeling; Osteoporosis; Interferon-gamma; Animals; Osteoclasts; Osteoblasts; Signal Transduction; Bone and Bones
PubMed: 38817601
DOI: 10.3389/fimmu.2024.1396122 -
Journal of Orthopaedic Surgery and... Aug 2023Osteoporosis (OP), due to microarchitectural alterations, is associated with decreased bone mass, declined strength, and increased fracture risk. Increased osteoblast...
BACKGROUND
Osteoporosis (OP), due to microarchitectural alterations, is associated with decreased bone mass, declined strength, and increased fracture risk. Increased osteoblast apoptosis contributes to the progression of OP. Natural compounds from herbs provide a rich resource for drug screening. Our previous investigation showed that geniposide (GEN), an effective compound from Eucommia ulmoides, could protect against the pathological development of OP induced by cholesterol accumulation.
METHODS
The rat OP models were duplicated. Dual-energy X-ray absorptiometry, hematoxylin and eosin staining, and immunohistochemistry were used to evaluate bone changes. TUNEL/DAPI staining assays were used for cell apoptosis detection. Protein expression was determined by western blotting assays.
RESULTS
A high-fat diet promoted OP development in vivo, and OX-LDL stimulated osteoblast apoptosis in vitro. GEN exhibited protective activities against OX-LDL-induced osteoblast apoptosis by increasing the NRF2 pathway and decreasing the NF-κB pathway. PDTC, an NF-κB inhibitor, could further promote the biological functions of GEN. In contrast, ML385, an NRF2 inhibitor, might eliminate GEN's protection.
CONCLUSION
GEN suppressed OX-LDL-induced osteoblast apoptosis by regulating the NRF2/NF-κB signaling pathway.
Topics: Animals; Rats; NF-kappa B; NF-E2-Related Factor 2; Signal Transduction; Osteoblasts; Apoptosis
PubMed: 37649066
DOI: 10.1186/s13018-023-04125-5 -
Nature Reviews. Endocrinology Jul 2024Bone development and bone remodelling during adult life are highly anabolic processes requiring an adequate supply of oxygen and nutrients. Bone-forming osteoblasts and... (Review)
Review
Bone development and bone remodelling during adult life are highly anabolic processes requiring an adequate supply of oxygen and nutrients. Bone-forming osteoblasts and bone-resorbing osteoclasts interact closely to preserve bone mass and architecture and are often located close to blood vessels. Chondrocytes within the developing growth plate ensure that bone lengthening occurs before puberty, but these cells function in an avascular environment. With ageing, numerous bone marrow adipocytes appear, often with negative effects on bone properties. Many studies have now indicated that skeletal cells have specific metabolic profiles that correspond to the nutritional microenvironment and their stage-specific functions. These metabolic networks provide not only skeletal cells with sufficient energy, but also biosynthetic intermediates that are necessary for proliferation and extracellular matrix synthesis. Moreover, these metabolic pathways control redox homeostasis to avoid oxidative stress and safeguard cell survival. Finally, several intracellular metabolites regulate the activity of epigenetic enzymes and thus control the fate and function of skeletal cells. The metabolic profile of skeletal cells therefore not only reflects their cellular state, but can also drive cellular activity. Insight into skeletal cell metabolism will thus not only advance our understanding of skeletal development and homeostasis, but also of skeletal disorders, such as osteoarthritis, diabetic bone disease and bone malignancies.
Topics: Humans; Animals; Osteoblasts; Chondrocytes; Bone and Bones; Osteoclasts; Bone Remodeling; Bone Development; Cell Differentiation; Homeostasis; Adipocytes
PubMed: 38499689
DOI: 10.1038/s41574-024-00969-x -
FASEB Journal : Official Publication of... Sep 2023Long-term spaceflight can result in bone loss and osteoblast dysfunction. Frizzled-9 (Fzd9) is a Wnt receptor of the frizzled family that is vital for osteoblast...
Long-term spaceflight can result in bone loss and osteoblast dysfunction. Frizzled-9 (Fzd9) is a Wnt receptor of the frizzled family that is vital for osteoblast differentiation and bone formation. In the present study, we elucidated whether Fzd9 plays a role in osteoblast dysfunction induced by simulated microgravity (SMG). After 1-7 days of SMG, osteogenic markers such as alkaline phosphatase (ALP), osteopontin (OPN), and Runt-related transcription factor 2 (RUNX2) were decreased, accompanied by a decrease in Fzd9 expression. Furthermore, Fzd9 expression decreased in the rat femur after 3 weeks of hindlimb unloading. In contrast, Fzd9 overexpression counteracted the decrease in ALP, OPN, and RUNX2 induced by SMG in osteoblasts. Moreover, SMG regulated phosphorylated glycogen synthase kinase-3β (pGSK3β) and β-catenin expression or sublocalization. However, Fzd9 overexpression did not affect pGSK3β and β-catenin expression or sublocalization induced by SMG. In addition, Fzd9 overexpression regulated protein kinase B also known as Akt and extracellular signal-regulated kinase (ERK) phosphorylation and induced F-actin polymerization to form the actin cap, press the nuclei, and increase nuclear pore size, thereby promoting the nuclear translocation of Yes-associated protein (YAP). Our study findings provide mechanistic insights into the role of Fzd9 in triggering actin polymerization and activating YAP to rescue SMG-induced osteoblast dysfunction and suggest that Fzd9 is a potential target to restore osteoblast function in individuals with bone diseases and after spaceflight.
Topics: Animals; Rats; Actins; beta Catenin; Cell Differentiation; Core Binding Factor Alpha 1 Subunit; Osteoblasts; Osteogenesis; Polymerization; Weightlessness; Frizzled Receptors; YAP-Signaling Proteins
PubMed: 37585277
DOI: 10.1096/fj.202300977R -
Bone Jul 2023Often, disorders of impaired bone formation involve not only a cell intrinsic defect in the ability of osteoblasts to form bone, but moreover a broader dysfunction of... (Review)
Review
Often, disorders of impaired bone formation involve not only a cell intrinsic defect in the ability of osteoblasts to form bone, but moreover a broader dysfunction of the skeletal microenvironment that limits osteoblast activity. Developing approaches to osteoanabolic therapy that not only augment osteoblast activity but moreover correct this microenvironmental dysfunction may enable both more effective osteoanabolic therapies and also addressing a broader set of indications where vasculopathy or other forms microenvironment dysfunction feature prominently. We here review evidence that SHN3 acts as a suppressor of not only the cell intrinsic bone formation activity of osteoblasts, but moreover of the creation of a local osteoanabolic microenvironment. Mice lacking Schnurri3 (SHN3, HIVEP3) display a very robust increase in bone formation, that is due to de-repression of ERK pathway signaling in osteoblasts. In addition to loss of SHN3 augmenting the differentiation and bone formation activity of osteoblasts, loss of SHN3 increases secretion of SLIT3 by osteoblasts, which in a skeletal context acts as an angiogenic factor. Through this angiogenic activity, SLIT3 creates an osteoanabolic microenvironment, and accordingly treatment with SLIT3 can increase bone formation and enhance fracture healing. These features both validate vascular endothelial cells as a therapeutic target for disorders of low bone mass alongside the traditionally targeted osteoblasts and osteoclasts and indicate that targeting the SHN3/SLIT3 pathway provides a new mechanism to induce therapeutic osteoanabolic responses.
Topics: Mice; Animals; Endothelial Cells; DNA-Binding Proteins; Osteoclasts; Bone and Bones; Osteoblasts; Osteogenesis; Cell Differentiation; Membrane Proteins
PubMed: 37030497
DOI: 10.1016/j.bone.2023.116761