Osteoblast and chondroblast differentiation

Aubin, Jane E.; Liu, F.; Malaval, Luc; Gupta, Ashwani

doi:10.1016/8756-3282(95)00183-e

Cited by 547 publications

(448 citation statements)

References 41 publications

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“…4E). Taking into account the observation that ALP is not expressed by osteoprogenitor cells (Aubin et al, 1995), this finding suggests that NG2 may precede ALP expression in immature osteoblasts during intramembranous ossification and that NG2 expression may be downregulated as these cells mature.…”

Section: Ng2 Localization During Intramembranous Ossificationmentioning

confidence: 85%

Expression of NG2 proteoglycan during endochondral and intramembranous ossification

Fukushi

Inatani

Yamaguchi

et al. 2003

Developmental Dynamics

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We have used immunohistochemistry to study the distribution of the NG2 proteoglycan during bone development in the mouse. At embryonic day 15.5, NG2 was strongly detected in the immature cartilage of developing limbs. After transient down-regulation in mature chondrocytes, NG2 was up-regulated during primary ossification, colocalizing with alkaline phosphatase and tenascin C. In the epiphyseal growth plates of newborn mouse tibia, NG2 and alkaline phosphatase exhibited overlapping patterns of expression by hypertrophic chondrocytes and by osteoblasts surrounding newly formed bone trabeculae. NG2 was down-regulated after puberty, being only faintly detectable in the tibial growth plates of 3-month-old mice. In cranial sutures, NG2 was strongly labeled in osteogenic bone fronts and in the suture matrix. Our results indicate that NG2 expression is up-regulated during both endochondral and intramembranous ossification, but is down-regulated as ossification is completed.

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Section: Ng2 Localization During Intramembranous Ossificationmentioning

confidence: 85%

Expression of NG2 proteoglycan during endochondral and intramembranous ossification

Fukushi

Inatani

Yamaguchi

et al. 2003

Developmental Dynamics

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“…Bone formation is characterized by a distinctive sequence of events beginning with the commitment of mesenchymal cells to osteoblast lineage, followed by osteoblast proliferation, growth, and differentiation, culminating in the formation of a mineralized extracellular matrix by terminally differentiated osteoblasts (25). Fluctuations in systemic [Ca 2ϩ ] o may influence these processes by inducing changes in circulating levels of PTH and 1,25(OH) 2 -vitamin D 3 .…”

Section: Resultsmentioning

confidence: 99%

Physiological changes in extracellular calcium concentration directly control osteoblast function in the absence of calciotropic hormones

Dvorák

Siddiqua

Ward

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

394

262

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We investigated the direct effects of changes in free ionized extracellular calcium concentrations ([Ca 2؉ ]o) on osteoblast function and the involvement of the calcium-sensing receptor (CaR) in mediating these responses. CaR mRNA and protein were detected in osteoblast models, freshly isolated fetal rat calvarial cells and murine clonal osteoblastic 2T3 cells, and in freshly frozen, undecalcified preparations of human mandible and rat femur. In fetal rat calvarial cells, elevating [Ca 2؉ ]o and treatment with gadolinium, a nonpermeant CaR agonist, resulted in phosphorylation of the extracellular signal-regulated kinases 1 and 2, Akt, and glycogensynthase kinase 3␤, consistent with signals of cell survival and proliferation. In agreement, cell number was increased under these conditions. Expression of the osteoblast differentiation markers core binding factor ␣1, osteocalcin, osteopontin, and collagen I mRNAs was increased by high [ (2, 3) and alter the levels of expression of some differentiation markers (4, 5). During mineralization, decreases in [Ca 2ϩ ] o are also likely to occur (6), but the effect of lowering [Ca 2ϩ ] o in bone cells has not been extensively addressed.The mechanism of [Ca 2ϩ ] o -sensing by osteoblasts is unclear. The parathyroid extracellular calcium-sensing receptor (CaR) is a key player in the maintenance of a constant systemic [Ca 2ϩ ] o , predominantly through regulation of parathyroid hormone (PTH) secretion and urinary calcium excretion (7,8). CaR is also present in osteoblasts (9 and references therein), where a functional role is currently debated. Recently two studies have shown that CaRdeficient mice exhibit an essentially normal skeletal phenotype when the hyperparathyroidism resulting from the lack of the parathyroid CaR is prevented (10, 11). Thus, it remains unclear whether the osteoblast CaR is a true regulator of bone function or whether its expression is vestigial (12).In this study, we investigated the effects of both decreasing and increasing [Ca 2ϩ ] o on osteoblast proliferation and intracellular signaling events, the expression of several osteoblast differentiation markers [core binding factor ␣1 (Cbfa1, also termed Runx2 and Osf2), osteocalcin (OC), osteopontin (OP), and type I collagen (collaI)], the activity of alkaline phosphatase (AlP), and mineralized nodule formation in the absence of systemic calciotropic factors, namely PTH and vitamin D. We further investigated the role played by the CaR in these events using an alternative, nonpermeant CaR agonist, gadolinium (Gd 3ϩ ) and a CaR inhibitor, NPS 89636 (a ''calcilytic''). We used well characterized osteoblast models, freshly isolated fetal rat calvarial cells (FRC) (13) and the clonal murine osteoblast cell line, 2T3 cells (14). The expression of CaR in freshly frozen sections of rat and human bone was also determined. Materials and MethodsAnimals. Sprague-Dawley rats (Charles River Breeding Laboratories) were killed by cervical dislocation and used in accordance to the U.K. Animals Scientific Procedures...

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“…Studies of osteoblastic cells from a number of animal species in two-dimensional (2D) cultures in vitro have revealed a general pattern of phenotypic progression during osteogenesis, 1,2,29,35 establishing a hierarchy of determination events from a common mesenchymal precursor and identifying the key regulator genes involved in osteogenic determination. 3,23,28,33 Also, cell-cell interactions via gap junctions, 6,9 cell shape, and cytoskeletal organization, dependent on integrin-mediated interaction with specific components of the endogenous extracellular matrix (ECM), 27,31 have been shown to determine cell metabolism, gene expression and differentiation, and cellular response to stimuli.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional cultures of normal human osteoblasts: proliferation and differentiation potential in vitro and upon ectopic implantation in nude mice

Ferrera

Poggi

Biassoni

et al. 2002

Bone

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Osteoblast and chondroblast differentiation

Cited by 547 publications

References 41 publications

Expression of NG2 proteoglycan during endochondral and intramembranous ossification

Expression of NG2 proteoglycan during endochondral and intramembranous ossification

Physiological changes in extracellular calcium concentration directly control osteoblast function in the absence of calciotropic hormones

Three-dimensional cultures of normal human osteoblasts: proliferation and differentiation potential in vitro and upon ectopic implantation in nude mice

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