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Frontiers in Cellular and Infection... 2015Bone cells, namely osteoblasts and osteoclasts work in concert and are responsible for bone extracellular matrix formation and resorption. This homeostasis is, in part,... (Review)
Review
Bone cells, namely osteoblasts and osteoclasts work in concert and are responsible for bone extracellular matrix formation and resorption. This homeostasis is, in part, altered during infections by Staphylococcus aureus through the induction of various responses from the osteoblasts. This includes the over-production of chemokines, cytokines and growth factors, thus suggesting a role for these cells in both innate and adaptive immunity. S. aureus decreases the activity and viability of osteoblasts, by induction of apoptosis-dependent and independent mechanisms. The tight relationship between osteoclasts and osteoblasts is also modulated by S. aureus infection. The present review provides a survey of the relevant literature discussing the important aspects of S. aureus and osteoblast interaction as well as the ability for antimicrobial peptides to kill intra-osteoblastic S. aureus, hence emphasizing the necessity for new anti-infectious therapeutics.
Topics: Animals; Antimicrobial Cationic Peptides; Apoptosis; Cell Survival; Host-Pathogen Interactions; Humans; Immunity, Innate; Microbial Viability; Osteoblasts; Osteoclasts; Osteomyelitis; Staphylococcal Infections; Staphylococcus aureus
PubMed: 26636047
DOI: 10.3389/fcimb.2015.00085 -
Laboratory Investigation; a Journal of... Feb 2019Osteoblast differentiation plays a critical role in bone formation and maintaining balance in bone remodeling. Runt-related transcription factor 2 (Runx2) is a central...
Osteoblast differentiation plays a critical role in bone formation and maintaining balance in bone remodeling. Runt-related transcription factor 2 (Runx2) is a central transcription factor regulating osteoblast differentiation and promoting bone mineralization. Until now, the molecular regulatory basis and especially the gene regulatory network of osteogenic differentiation have been unclear. Krüppel-like factor 2 (KLF2) is a zinc finger structure and DNA-binding transcription factor. The current study aimed to investigate the physiological function of KLF2 in osteoblast differentiation. Our results indicate that KLF2 is expressed in pre-osteoblast MC3T3-E1 cells and primary osteoblasts. Interestingly, KLF2 expression is increased in osteoblasts during the osteoblastic differentiation process. Overexpression of KLF2 in MC3T3-E1 cells promoted the expression of the osteoblastic differentiation marker genes Alp, Osx, and Ocn, and stimulated mineralization by increasing Runx2 expression at both the mRNA and protein levels. In contrast, knockdown of KLF2 produced the opposite effects. Importantly, we found that KLF2 could physically interact with Runx2. KLF2 promoted osteoblast differentiation by regulating Runx2 and physically interacting with Runx2. Taken together, the findings of this study identify KLF2 as a novel regulator of osteoblast differentiation. Our findings suggest that KLF2 might be a new therapeutic target for bone disease.
Topics: Animals; Cell Differentiation; Cell Line; Core Binding Factor Alpha 1 Subunit; Gene Knockdown Techniques; Human Umbilical Vein Endothelial Cells; Humans; Kruppel-Like Transcription Factors; Mice; Osteoblasts
PubMed: 30429507
DOI: 10.1038/s41374-018-0149-x -
Trends in Molecular Medicine May 2009Osteoblasts are key components of the bone multicellular unit and have a seminal role in bone remodeling, which is an essential function for the maintenance of the... (Review)
Review
Osteoblasts are key components of the bone multicellular unit and have a seminal role in bone remodeling, which is an essential function for the maintenance of the structural integrity and metabolic capacity of the skeleton. The coordinated function of skeletal cells is regulated by several hormones, growth factors and mechanical cues that act via interconnected signaling networks, resulting in the activation of specific transcription factors and, in turn, their target genes. Bone cells are responsive to mechanical stimuli and this is of pivotal importance in developing biomechanical strategies for the treatment of osteodegenerative diseases. Here, we review the molecular pathways and players activated by mechanical stimulation during osteoblastic growth, differentiation and activity in health, and consider the role of mechanostimulatory approaches in treating various bone pathophysiologies.
Topics: Animals; Bone Diseases; Cell Differentiation; Humans; Intercellular Signaling Peptides and Proteins; Mechanotransduction, Cellular; Models, Biological; Osteoblasts; Physical Therapy Modalities; Signal Transduction; Stress, Mechanical; Transcription Factors
PubMed: 19362057
DOI: 10.1016/j.molmed.2009.03.001 -
European Cells & Materials Jul 2012The process of bone formation, remodelling and healing involves a coordinated action of various cell types. Advances in understanding the biology of osteoblast cells... (Review)
Review
The process of bone formation, remodelling and healing involves a coordinated action of various cell types. Advances in understanding the biology of osteoblast cells during these processes have been enabled through the use of various in vitro culture models from different origins. In an era of intensive bone tissue engineering research, these cell models are more and more often applied due to limited availability of primary human osteoblast cells. While they are a helpful tool in developing novel therapies or biomaterials; concerns arise regarding their phenotypic state and differences in relation to primary human osteoblast cells. In this review we discuss the osteoblastic development of some of the available cell models; such as primary human, rat, mouse, bovine, ovine and rabbit osteoblast cells; as well as MC3T3-E1, MG-63 and SaOs-2 cell lines, together with their advantages and disadvantages. Through this, we provide suggestions on the selection of the appropriate and most relevant osteoblast model for in vitro studies, with specific emphasis on cell-material based studies.
Topics: Animals; Bone and Bones; Cattle; Cell Differentiation; Cell Line; Humans; Mice; Models, Biological; Osteoblasts; Primary Cell Culture; Rabbits; Rats; Sheep; Species Specificity; Tissue Engineering
PubMed: 22777949
DOI: 10.22203/ecm.v024a01 -
Journal of Cellular Biochemistry Jul 1994Control of osteoblast growth and development can be characterized from receptor mediated events to nuclear messengers controlling gene transcription. From this analysis... (Review)
Review
Control of osteoblast growth and development can be characterized from receptor mediated events to nuclear messengers controlling gene transcription. From this analysis it is possible to formulate a model to explain the reciprocal relationship between growth and differentiation as well as differential cytokine modulation of osteoblast function. Central to this model are putative tissue specific transcriptional switches (possibly of the bHLH gene superfamily) that may repress proliferation and permit the regulation of mature osteoblast phenotypic characteristics. This model proposes that in post-mitotic differentiated osteoblasts, tissue specific transcription factors determine the capacity to express osteoblastic characteristic, whereas receptor activated signalling cascades, namely, cAMP/protein kinase A, receptor serine/threonine kinase, and vitamin D receptor-dependent pathways, regulate mature osteoblast-specific gene expression. Activated differentiation switches also may feedback to transcriptionally repress proliferation. Conversely, in preosteoblasts, in which differentiation switches are turned off, distinct signalling cascades involving tyrosine kinases, PKC, and calcium/calmodulin regulate proliferation. Proliferating preosteoblasts also exhibit negative modulation of maturation either through inactivation of putative tissue-specific transcription factors and/or through AP-1 dependent phenotype suppression of genes expressed in mature osteoblast. Thus, the final outcome of transcriptional regulation of osteoblast function results from complex interactions between signalling pathways and permissive differentiating transcription factors. Though many aspects of this model remain speculative and require confirmation, it serves as a useful conceptual framework to further investigate the differential control of osteoblast proliferation and differentiation that may lead to improved pharmacologic ways to manipulate bone formation in vivo.
Topics: Cell Differentiation; Cell Division; Cytokines; Gene Expression Regulation; Growth Substances; Humans; Osteoblasts; Signal Transduction; Transcription, Genetic
PubMed: 7962162
DOI: 10.1002/jcb.240550307 -
Biophysical Chemistry Dec 2020Based on the osteogenic effect, triiodothyronine (T3) plays an important role in bone growth and development. Autophagy contributes to osteoblast formation and...
Based on the osteogenic effect, triiodothyronine (T3) plays an important role in bone growth and development. Autophagy contributes to osteoblast formation and subsequent osteogenesis. Our study aims to explore the relationship among T3, autophagy and osteogenesis. In this study, cranial primary osteoblasts were obtained from 2 to 3 weeks-old Sprague Dawley (SD) rat fetuses. Osteoblasts were treated with T3, and then the autophagic parameters of Osteoblasts (including autophagic proteins, LC3 conversion rate and autophagosome formation) were observed through Western Blotting and Transmission Electron Microscopy. Next, after using autophagic pharmacological inhibitors (3-MA and chloroquine) and silencing vectors of autophagic genes (BECN1, Atg5 and Atg7) to downregulate autophagic activity, osteoblast proliferation and osteoblastic gene expression were detected using cell counting kit-8 (CCK-8) and quantitative real-time PCR (qRT-PCR) assays, respectively. Ultimately, the mice treated with partial thyroidectomy (PTx mice) were used to further observe the effect of T3 on the formation and autophagy of osteoblasts in trabecular bone in vivo. Our results show that T3 enhances osteoblast autophagy. Autophagy suppression with 3-MA, chloroquine or autophagy-genes knockdown reverses T3-promoted osteoblast formation. In vivo assays showed that the formation and autophagy of osteoblasts in bone tissue were reduced in T3-deficient young mice. Overall, T3 can promote osteoblast formation by activation of autophagy.
Topics: Animals; Autophagy; Cell Proliferation; Cells, Cultured; Mice; Mice, Inbred C57BL; Osteoblasts; Osteogenesis; Rats; Rats, Sprague-Dawley; Triiodothyronine
PubMed: 33010728
DOI: 10.1016/j.bpc.2020.106483 -
Microscopy Research and Technique Feb 1996Knowledge of the number and kinds of differentiation steps characterizing cells of the osteoblast lineage is inadequate. To analyze further osteoblast differentiation, a... (Review)
Review
Knowledge of the number and kinds of differentiation steps characterizing cells of the osteoblast lineage is inadequate. To analyze further osteoblast differentiation, a number of labs have generated monoclonal antibodies to osteogenic cells, derived from both normal bone and osteosarcomas. A variety of immunolabelling patterns on primary cell cultures, cell lines, and tissue sections has been reported, including cell surface, cytoplasmic, and extracellular matrix-associated patterns. Most of the antibodies selected recognize predominantly the mature osteoblast and osteocyte; in addition, however, antibodies have been generated that recognize pre-osteoblasts. Some recognize cells of both the osteoblast and chondroblast lineages and may contribute to a better understanding of the lineage and phenotypic relationships between these two cell types. In addition to recognition in vivo of cell subpopulations of discrete maturational stages, changes in the immunolabelling patterns in vitro have also documented a differentiation sequence in cells undergoing osteogenesis in cell and tissue cultures. In at least two cases, the antibodies have been used to isolate subpopulations of cells from bone, including relatively pure populations of osteocytes. With the exception of several antibodies that are against alkaline phosphatase or known matrix proteins including osteocalcin, the nature of the macromolecular species recognized by most of the antibodies generated to date are unknown. Recently, however, one antibody was used to clone the cDNA for the beta-galactoside-binding lectin, galectin 3 or epsilon binding protein (epsilon BP; IgE-binding protein; Mac-2), from a lambda gt11 osteoblast expression library; another was used to clone from an ROS 17/2.8-COS cell expression library the cDNA for OTS-8, a putative target gene of early response genes stimulated in response to phorbol esters in MC3T3-E1 cells. Neither of these macromolecules had previously been identified in bone cells, but the recent molecular and cellular analyses have shown them to be developmentally and/or hormonally regulated in osteoblastic cells. These antibodies extend the available markers and support earlier observations that a variety of molecules are differentially expressed by cells at different stages of the osteoblast lineage. This chapter will not be an exhaustive survey of all immunocytochemical and immunohistochemical analyses of osteogenic cells and tissues but will focus on the approach of eliciting novel monoclonal antibodies by the injection of osteogenic cells or crude bone extracts and its potential for establishing new markers of the osteoblast lineage. We have not included a large number of studies documenting the use of antibodies raised against several known bone matrix proteins; while these have been crucial in developing our current understanding of osteogenic differentiation, we sought rather to highlight the potential of the "random" injection approach.
Topics: Animals; Antibodies, Monoclonal; Biomarkers; Bone and Bones; Cartilage; Cell Lineage; Humans; Microscopy, Fluorescence; Osteoblasts; Rats
PubMed: 8845513
DOI: 10.1002/(SICI)1097-0029(19960201)33:2<128::AID-JEMT4>3.0.CO;2-P -
Bone Jan 2015Skeletal (marrow stromal) stem cells (BMSCs) are a group of multipotent cells that reside in the bone marrow stroma and can differentiate into osteoblasts, chondrocytes... (Review)
Review
Skeletal (marrow stromal) stem cells (BMSCs) are a group of multipotent cells that reside in the bone marrow stroma and can differentiate into osteoblasts, chondrocytes and adipocytes. Studying signaling pathways that regulate BMSC differentiation into osteoblastic cells is a strategy for identifying druggable targets for enhancing bone formation. This review will discuss the functions and the molecular mechanisms of action on osteoblast differentiation and bone formation; of a number of recently identified regulatory molecules: the non-canonical Notch signaling molecule Delta-like 1/preadipocyte factor 1 (Dlk1/Pref-1), the Wnt co-receptor Lrp5 and intracellular kinases. This article is part of a Special Issue entitled: Stem Cells and Bone.
Topics: Animals; Bone and Bones; Cell Differentiation; Humans; Intracellular Space; Osteoblasts; Signal Transduction; Stem Cells; Stromal Cells
PubMed: 25138551
DOI: 10.1016/j.bone.2014.07.028 -
Environmental Toxicology Dec 2020In this study, we report the potential of cannabidiol, one of the major cannabis constituents, for enhancing osteoblastic differentiation in U2OS and MG-63 cells....
In this study, we report the potential of cannabidiol, one of the major cannabis constituents, for enhancing osteoblastic differentiation in U2OS and MG-63 cells. Cannabidiol increased the expression of Angiopoietin1 and the enzyme activity of alkaline phosphatase in U2OS and MG-63. Invasion and migration assay results indicated that the cell mobility was activated by cannabidiol in U2OS and MG-63. Western blotting analysis showed that the expression of tight junction related proteins such as Claudin1, Claudin4, Occuludin1, and ZO1 was increased by cannabidiol in U2OS and MG-63. Alizarin Red S staining analysis showed that calcium deposition and mineralization was enhanced by cannabidiol in U2OS and MG-63. Western blotting analysis indicated that the expression of osteoblast differentiation related proteins such as distal-less homeobox 5, bone sialoprotein, osteocalcin, type I collagen, Runt-related transcription factor 2 (RUNX2), osterix (OSX), and alkaline phosphatase was time dependently upregulated by cannabidiol in U2OS and MG-63. Mechanistically, cannabidiol-regulated osteoblastic differentiation in U2OS and MG-63 by strengthen the protein-protein interaction among RUNX2, OSX, or the phosphorylated p38 mitogen-activated protein kinase (MAPK). In conclusion, cannabidiol increased Angiopoietin1 expression and p38 MAPK activation for osteoblastic differentiation in U2OS and MG-63 suggesting that cannabidiol might provide a novel therapeutic option for the bone regeneration.
Topics: Alkaline Phosphatase; Angiopoietin-1; Cannabidiol; Cell Differentiation; Cell Line; Cell Movement; Core Binding Factor Alpha 1 Subunit; Humans; Osteoblasts; Osteogenesis; Phosphorylation; p38 Mitogen-Activated Protein Kinases
PubMed: 32656944
DOI: 10.1002/tox.22996 -
Modulatory effect of omega-3 polyunsaturated fatty acids on osteoblast function and bone metabolism.Prostaglandins, Leukotrienes, and... Jun 2003Recent investigations indicate that the type and amount of polyunsaturated fatty acids (PUFA) influence bone formation in animal models and osteoblastic cell functions... (Review)
Review
Recent investigations indicate that the type and amount of polyunsaturated fatty acids (PUFA) influence bone formation in animal models and osteoblastic cell functions in culture. In growing rats, supplementing the diet with omega-3 PUFA results in greater bone formation rates and moderates ex vivo prostaglandin E(2) production in bone organ cultures. A protective effect of omega-3 PUFA on minimizing bone mineral loss in ovariectomized rats has also been reported. The actions of omega-3 fatty acids on bone formation appear to be linked to altering osteoblast functions. Herein we describe experiments with MC3T3-E1 osteoblast-like cells that support findings in vivo where omega-3 PUFA modulated COX-2 protein expression, reduced prostaglandin E(2) production, and increased alkaline phosphatase activity. Other studies indicate that the dietary source of PUFA may affect protein expression of Cbfa1 and nodule formation in fetal rat calvarial cells.
Topics: Animals; Bone and Bones; Cyclooxygenase 2; Dinoprostone; Fatty Acids, Omega-3; Humans; Isoenzymes; Membrane Proteins; Morphogenesis; Osteoblasts; Ovariectomy; Prostaglandin-Endoperoxide Synthases
PubMed: 12798659
DOI: 10.1016/s0952-3278(03)00063-2