Signal transducer and activator of transcription 3 (Stat3) is a member of the Stat family of proteins involved in signaling in many different cell types, including osteocytes. Osteocytes are considered major mechanosensing cells in bone due to their intricate dendritic networks able to sense changes in physical force and to orchestrate the response of osteoclasts and osteoblasts. We examined the role of Stat3 in osteocytes by generating mice lacking Stat3 in these cells using the Dmp-1(8kb)-Cre promoter (Stat3cKO mice). Compared to age-matched littermate controls, Stat3cKO mice of either sex (18 weeks old) exhibit reduced bone formation indices, decreased osteoblasts and increased osteoclasts, and altered material properties, without detectable changes in bone mineral density (BMD) or content of either trabecular or cortical bone. In addition, Stat3cKO mice of either sex show significantly decreased load-induced bone formation. Furthermore, pharmacologic inhibition of Stat3 in osteocytes with WP1066 blocked the increase in cytosolic calcium induced by ATP, a mediator of the cellular responses to sheer stress. WP1066 also increased reactive oxygen species (ROS) production in cultured MLO-Y4 osteocytes. These data demonstrate that Stat3 is a critical mediator of mechanical signals received by osteocytes and suggest that osteocytic Stat3 is a potential therapeutic target to stimulate bone anabolism.
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http://dx.doi.org/10.1016/j.bonr.2019.100218 | DOI Listing |
Bone
January 2025
Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada; Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8, Canada; Department of Mechanical and Materials Engineering, Queen's University, Kingston, ON K7L3N6, Canada. Electronic address:
Yes-associated protein (YAP) is a mechanosensitive protein crucial for bone remodeling. Although research has identified pathways and components involved in YAP regulation, the precise mechanisms of its localization during Piezo1 activation or vibration remain unclear. Piezo1, a mechanosensitive ion channel, allows calcium ions to flow into cells upon activation.
View Article and Find Full Text PDFInt J Mol Sci
November 2023
Department of Radiological Hygiene, Institute of Radiation Medicine, Fudan University, 2094 Xietu Road, Shanghai 200032, China.
The imbalance that occurs in bone remodeling induced by irradiation (IR) is the disruption of the balance between bone formation and bone resorption. In this study, primary osteocytes (OCYs) of femoral and tibial origin were cultured and irradiated. It was observed that irradiated OCY showed extensive DNA damage, which led to the initiation of a typical phenotype of cellular senescence, including the secretion of senescence-associated secretory phenotype (SASP), especially the C-C motif chemokine ligand 5 (CCL5).
View Article and Find Full Text PDFNat Commun
November 2022
Department of Biomedical Sciences and Comprehensive Care, Indiana University School of Dentistry, Indianapolis, IN, 46202-5126, USA.
The impact of bone cell activation on bacterially-induced osteolysis remains elusive. Here, we show that matrix-embedded osteocytes stimulated with bacterial pathogen-associated molecular patterns (PAMPs) directly drive bone resorption through an MYD88-regulated signaling pathway. Mice lacking MYD88, primarily in osteocytes, protect against osteolysis caused by calvarial injections of bacterial PAMPs and resist alveolar bone resorption induced by oral Porphyromonas gingivalis (Pg) infection.
View Article and Find Full Text PDFJ Endocrinol
October 2022
Bone Cell Biology and Disease Unit, St Vincent's Institute of Medical Research, Fitzroy, Australia.
Bone strength is partially determined during cortical bone consolidation, a process comprising coalescence of peripheral trabecular bone and its progressive mineralisation. Mice with genetic deletion of suppressor of cytokine signalling 3 (Socs3), an inhibitor of STAT3 signalling, exhibit delayed cortical bone consolidation, indicated by high cortical porosity, low mineral content, and low bone strength. Since leptin receptor (LepR) is expressed in the osteoblast lineage and is suppressed by SOCS3, we evaluated whether LepR deletion in osteocytes would rectify the Dmp1cre.
View Article and Find Full Text PDFBone strength is determined by the structure and composition of its thickened outer shell (cortical bone), yet the mechanisms controlling cortical consolidation are poorly understood. Cortical bone maturation depends on SOCS3-mediated suppression of IL-6 cytokine-induced STAT3 phosphorylation in osteocytes, the cellular network embedded in bone matrix. Because SOCS3 also suppresses granulocyte-colony-stimulating factor receptor (G-CSFR) signaling, we here tested whether global G-CSFR (Csf3r) ablation altereed bone structure in male and female mice lacking SOCS3 in osteocytes, (Dmp1 :Socs3 mice).
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