Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to characterize fibroblastic colony-forming units (CFU-F) from murine bone marrow in relation to osteogenesis, adherent cells of 7-day-old BALB/c mouse bone marrow cultures were infected with a recombinant retrovirus (N2/ delta fosB) containing the bacterial neomycin resistance gene. One of the G418-resistant clones, MN7, was selected for further analysis on the basis of its high expression of the bone-specific alkaline phosphatase. The cells have now been in culture for more than 1 year and maintain a stable phenotype. The osteogenic nature of the immortalized clone MN7 was demonstrated as follows: (1) Mineralization was detected by 85Sr uptake and with the Von Kossa staining method only after in vitro cultivation on a collagen type I matrix. (2) Osteoblastic phenotype markers, including the synthesis of type I collagen, osteonectin, and the bone-specific isoenzyme of alkaline phosphatase were expressed in vitro. (3) MN7 cells responded to bone effectors such as parathyroid hormone and 1,25-dihydroxyvitamin D3. (4) Intraperitoneal injection of MN7 cells into 1-day-old BALB/c mice produced typical osteosarcomas in all animals. We conclude that MN7, derived entirely in vitro from a stromal CFU-F colony, represents a stable murine osteosarcoma cell line expressing the osteoblastic phenotype and provides the first direct evidence needed to establish adult mouse marrow-derived, nonhematopoietic stromal cells as osteoprogenitors.
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PMID:Establishment of an osteogenic cell line derived from adult mouse bone marrow stroma by use of a recombinant retrovirus. 157 49

Interleukin 10 (IL-10) suppressed TGF-beta synthesis in mouse bone marrow cultures. Coincidingly, IL-10 down-regulated the production of bone proteins including alkaline phosphatase (ALP), collagen and osteocalcin, and the formation of mineralized extracellular matrix. The mAb 1D11.16 which neutralizes TGF-beta 1 and TGF-beta 2, induced suppressive effects comparable to IL-10 when administered before the increase of cell proliferation in the culture. It appears that mainly TGF-beta 1 plays a role in this system since (a) TGF-beta 2 levels were undetectable in supernatants from osteogenic cultures, (b) no effect was observed when the anti-TGF-beta 2 neutralizing mAb 4C7.11 was added and (c) the suppressive effect of IL-10 could be reversed by adding exogenous TGF-beta 1. It is unlikely that TGF-beta 1 modulates osteogenic differentiation by changing the proliferative potential of marrow cells since 1D11.16 did not affect [3H]thymidine ([3H]TdR) incorporation or the number of fibroblast colony forming cells (CFU-F) which harbor the osteoprogenitor cell population. Furthermore, 1D11.16 did not alter [3H]TdR uptake by the cloned osteoprogenitor cell lines MN7 and MC3T3. Light and scanning electron microscopy showed that IL-10 and 1D11.16 induced comparable morphological changes in the marrow cultures. Control cultures contained flat adherent cells embedded in a mineralized matrix. In contrast, IL-10 and 1D11.16 treated cultures were characterized by round non-adherent cells and the absence of a mineralized matrix. In this study, the mechanism by which IL-10 suppresses the osteogenic differentiation of mouse bone marrow was identified as inhibition of TGF-beta 1 production which is essential for osteogenic commitment of bone marrow cells.
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PMID:Interleukin 10 inhibits transforming growth factor-beta (TGF-beta) synthesis required for osteogenic commitment of mouse bone marrow cells. 810 54

The steady-state mRNA levels of different osteogenic markers and their modulation by 17 beta-estradiol in the murine osteogenic cell line MN7 during proliferation and differentiation in vitro were examined. mRNA of collagen type I, osteopontin, bone morphogenetic protein 2, plasminogen activator inhibitor 1, alkaline phosphatase, and osteocalcin were isolated from MN7 cultures grown for 7, 11, 14, and 17 days. Northern blot analysis revealed steady-state transcript levels depending on MN7 cell density. The order of appearance of Col I, OP, ALP, and OC resembled the pattern of gene expression observed during osteoblast maturation in vitro. Furthermore, PAI-1 steady-state transcript levels peaked during subconfluence (day 11) but BMP-2 RNA levels reached their maximum after the culture had become confluent. 17 beta-Estradiol showed a dose-dependent stimulation of the different osteoblast-related transcripts present in a subconfluent MN7 culture at the time of analysis. Furthermore, the effects of 17 beta-estradiol (17 beta E2) at different time points of MN7 growth varied according to cell density. 17 beta E2 added to subconfluent MN7 cultures modulated the transcript level in a negative way, but RNA levels of the investigated osteogenic markers in confluent cultures were stimulated with 100 nM 17 beta-estradiol. No effect of 17 beta-estradiol on proliferation was detected. The present studies have revealed differential osteoblast gene expression related to MN7 cell proliferation and differentiation in vitro and emphasize the importance of 17 beta E2 in the regulation of growth of this preosteoblastic cell line in vitro.
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PMID:Characterization of the stromal osteogenic cell line MN7: mRNA steady-state level of selected osteogenic markers depends on cell density and is influenced by 17 beta-estradiol. 814 Sep 31

Murine bone marrow cells synthesize bone proteins, including alkaline phosphatase (ALP), collagen type I, and osteocalcin, and form a mineralized extracellular matrix when cultured in the presence of beta-glycerophosphate and vitamin C. Interleukin-10 (IL-10) suppressed the synthesis of these bone proteins and mineralization without affecting cell proliferation. In addition, mRNA levels for the latter proteins were reduced in IL-10-treated cultures. This inhibitory effect was most outspoken when IL-10 was added before ALP activity peaked, eg, day 15 of culture. No significant effect was observed when IL-10 was added at later time points. This finding suggests that IL-10 acts at osteogenic differentiation stages that precede ALP expression but is ineffective on cells that progressed beyond this maturation stage. Likewise, IL-10 appeared to be unable to block both ALP activity and collagen synthesis in the preosteosteoblastic cell lines MN7 and MC3T3 that constitutively synthesize these proteins. Whereas IL-10 did not alter the number of fibroblast colony-forming cells of the marrow, it significantly reduced their osteogenic differentiation potential. In contrast to control cultures, IL-10-treated stroma was unable to either synthesize osteocalcin or to mineralize when subcultured over a 25-day period in the absence of IL-10. The inhibitory activity of IL-10 coincided with significant changes in stroma morphology. Whereas control cultures contained mainly flat adherent polygonal cells, significant numbers of rounded semiadherent to nonadherent cells were observed in the presence of IL-10. Scanning and transmission electron microscopy showed that, in contrast to control cultures, IL-10-treated stromas completely lacked a mineralized extracellular matrix. Collectively, these data suggest that IL-10 may have important regulatory effects on bone biology because of its capacity to downregulate early steps of osteogenic differentiation.
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PMID:Interleukin-10 inhibits the osteogenic activity of mouse bone marrow. 840 Feb 87