Journal ArticleDOI
Parathyroid hormone regulates osteoblast differentiation positively or negatively depending on the differentiation stages.
Yukihiro Isogai,Takuhiko Akatsu,Toshinori Ishizuya,Akira Yamaguchi,Masayuki Hori,Naoyuki Takahashi,Tatsuo Suda +6 more
TLDR
PTH may preferentially stimulate osteoblast differentiation in immature osteoblasts but inhibit it in more mature cells, indicating that PTH exerts opposite effects on the phenotypic expression of osteoblast, depending on their differentiation stages of osteoclasts.Abstract:
The effects of parathyroid hormone (1-34) (PTH (1-34) on osteoblast differentiation were investigated using primary osteoblast-like cells isolated from newborn mouse calvaria. The osteoblast-like cells cultured at low cell densities, in which the cells remained in a subconfluent state at the end of culture, were exposed for 7 days to PTH. This stimulated alkaline phosphatase (ALP) activity in a dose-dependent manner. In contrast, PTH dose-dependently inhibited both ALP activity and osteocalcin production in cells inoculated at high cell densities, in which they had reached a confluent state before the end of culture. The changes of ALP activity by PTH were accompanied with the expression of ALP messenger RNA. PTH induced no changes of the hydroxyproline content in the cell layer when the cells were exposed to the hormone at a subconfluent state, but reduced the content at a postconfluent state. The stimulation of ALP activity by PTH at a preconfluent state was retained even after the removal of PTH from the culture media. The opposite effect of PTH, observed between the preconfluent and the postconfluent state, was reproduced by adding dibutyryl cyclic adenosine monophosphate (cAMP) or forskolin, but not by adding phorbol myristate acetate. In a colony-forming unit fibroblastic (CFU-F) assay, using bone marrow cells isolated from tibiae of 10-week-old mice, PTH induced no changes in the total number of CFU-Fs, but increased the proportion of ALP-positive colonies. These results indicate that PTH exerts opposite effects on the phenotypic expression of osteoblasts, depending on their differentiation stages of osteoblasts. PTH may preferentially stimulate osteoblast differentiation in immature osteoblasts but inhibit it in more mature cells.read more
Citations
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Journal ArticleDOI
SOST is a target gene for PTH in bone.
TL;DR: It is shown that PTH directly inhibits SOST transcription in vivo and in vitro, suggesting that SOST regulation may play a role in mediating PTH action in bone.
Journal ArticleDOI
Modeling the interactions between osteoblast and osteoclast activities in bone remodeling
TL;DR: A mathematical model explaining the interactions between osteoblasts and osteoclasts, two cell types specialized in the maintenance of the bone integrity, predicts that combinations of anti-resorptive and anabolic therapies provide significant benefits compared with monotherapy, especially for certain type of skeletal disease.
Journal ArticleDOI
Parathyroid hormone exerts disparate effects on osteoblast differentiation depending on exposure time in rat osteoblastic cells.
Toshinori Ishizuya,Satoshi Yokose,Masayuki Hori,Toshiharu Noda,Tatsuo Suda,Shusaku Yoshiki,Akira Yamaguchi +6 more
TL;DR: The results suggest that PTH has diverse effects on osteoblast differentiation depending on the exposure time in vitro mediated through different signal transduction systems, and at least in part the in vivo action of PTH that varies with the mode of administration.
Journal ArticleDOI
Parathyroid hormone secretion and action: evidence for discrete receptors for the carboxyl-terminal region and related biological actions of carboxyl- terminal ligands.
TL;DR: The review summarizes current knowledge of the structure, secretion, and metabolism of PTH and its circulating fragments, details available information concerning the pharmacology and actions of carboxyl-terminal PTH receptors, and frames their likely biological and clinical significance.
Journal ArticleDOI
Mediators of the biphasic responses of bone to intermittent and continuously administered parathyroid hormone
TL;DR: In this model system, the data suggest that intermittent PTH treatment enhances osteoblast differentiation through an IGF‐I dependent mechanism and continuous PTHtreatment enhances osteoclastogenesis through reciprocal increases in RANKL and decreases in OPG.
References
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Journal ArticleDOI
A simple, rapid, and sensitive DNA assay procedure.
C Labarca,Kenneth Paigen +1 more
TL;DR: The dissociation of chromatin is critical to accurate determinations of DNA in biological materials using this method, which can detect as little as 10 ng of DNA with rather unsophisticated instrumentation.
Journal ArticleDOI
Progressive development of the rat osteoblast phenotype in vitro: Reciprocal relationships in expression of genes associated with osteoblast proliferation and differentiation during formation of the bone extracellular matrix
Thomas A. Owen,Michael A. Aronow,Victoria Shalhoub,Leesa M. Barone,Laurens G. Wilming,Melissa S. Tassinari,Mary Beth Kennedy,Shirwin M. Pockwinse,Jane B. Lian,Gary S. Stein +9 more
TL;DR: The relationship of cell proliferation to the temporal expression of genes characterizing a developmental sequence associated with bone cell differentiation was examined in primary diploid cultures of fetal calvarial derived osteoblasts by the combined use of autoradiography, histochemistry, biochemistry, and mRNA assays of osteoblast cell growth and phenotypic genes.
Progressive Development of the Rat Osteoblast Phenotype In Vitro: Reciprocal Relationships in Expression of Genes Associated With Osteoblast Proliferation and Differentiation During Formation of the
Thomas A. Owen,Michael A. Aronow,Victoria Shalhoub,Leesa M. Barone,Laurens G. Wilming,Melissa S. Tassinari,Mary Beth Kennedy,Jane B. Lian,Gary S. Stein +8 more
TL;DR: In this article, the relationship of cell proliferation to the temporal expression of genes characterizing a developmental sequence associated with bone cell differentiation was examined in primary diploid cultures of fetal calvarial derived osteoblasts by the combined use of autoradiography, histochemistry, biochemistry, and mRNA assays of osteoblast cell growth and phenotypic genes.
Book ChapterDOI
Stromal Stem Cells: Marrow‐Derived Osteogenic Precursors
Maureen Owen,A. J. Friedenstein +1 more
TL;DR: In vivo and in vitro studies have shown that CFU-F are a heterogeneous population of stem and progenitor cells and that their differentiation in vitro can be modified at the colony level, which supports the hypothesis that there are stromal stem cells present in the soft connective tissues associated with marrow and bone surfaces.
Journal ArticleDOI
Bone marrow osteogenic stem cells: in vitro cultivation and transplantation in diffusion chambers
TL;DR: The high proliferative potential of bone marrow FCFC and their ability to serve as common precursors of bone and cartilage‐forming cells makes them probable candidates for the role of osteogenic stem cells.