NFATc1 and NFATc2 are functionally redundant in the immune system, but it was suggested that NFATc1 is required exclusively for differentiation of osteoclasts in the skeletal system. Here we provide genetic evidence that NFATc1 is essential for osteoclast differentiation in vivo by adoptive transfer of NFATc1 −/− hematopoietic stem cells to osteoclast-deficient Fos −/− mice, and by Fos −/− blastocyst complementation, thus avoiding the embryonic lethality of NFATc1 −/− mice. However, in vitro osteoclastogenesis in NFATc1-deficient cells was rescued by ectopic expression of NFATc2. The discrepancy between the in vivo essential role of NFATc1 and the in vitro effect of NFATc2 was attributed to selective autoregulation of the NFATc1 gene by NFAT through its promoter region. This suggested that an epigenetic mechanism contributes to the essential function of NFATc1 in cell lineage commitment. Thus, this study establishes that NFATc1 represents a potential therapeutic target for bone disease and reveals a mechanism that underlies the essential role of NFATc1 in bone homeostasis.

The subcellular locations of prostaglandin endoperoxide synthase-1 and -2 (PGHS-1 and -2) were determined by quantitative confocal fluorescence imaging microscopy in murine 3T3 cells and human and bovine endothelial cells using immunocytofluorescence with isozyme-specific antibodies. In all of the cell types examined, PGHS-1 immunoreactivity was found equally distributed in the endoplasmic reticulum (ER) and nuclear envelope (NE). PGHS-2 immunoreactivity was also present in the ER and NE. However, PGHS-2 staining was twice as concentrated in the NE as in the ER. A histofluorescence staining method was developed to localize cyclooxygenase/peroxidase activity. In quiescent 3T3 cells, which express only PGHS-1, histofluorescent staining was most concentrated in the perinuclear cytoplasmic region. In contrast, histochemical staining for PGHS-2 activity was about equally intense in the nucleus and in the cytoplasm, a pattern of activity staining distinct from that observed with PGHS-1. Our results indicate that there are significant differences in the subcellular locations of PGHS-1 and PGHS-2. It appears that PGHS-1 functions predominantly in the ER whereas PGHS-2 may function in the ER and the NE. We speculate that PGHS-1 and PGHS-2 acting in the ER and PGHS-2 functioning in the NE represent independent prostanoid biosynthetic systems.

No abstract

Inkjet printers are capable of printing at high resolution by ejecting extremely small ink drops. Established printing technology will be able to seed living cells, at micrometer resolution, in arrangements similar to biological tissues. We describe the use of a biocompatible inkjet head and our investigation of the feasibility of microseeding with living cells. Living cells are easily damaged by heat; therefore, we used an electrostatically driven inkjet system that was able to eject ink without generating significant heat. Bovine vascular endothelial cells were prepared and suspended in culture medium, and the cell suspension was used as "ink" and ejected onto culture disks. Microscopic observation showed that the endothelial cells were situated in the ejected dots in the medium, and that the number of cells in each dot was dependent on the concentration of the cell suspension and ejection frequency chosen. After the ejected cells were incubated for a few hours, they adhered to the culture disks. Using our non-heat-generating, electrostatically driven inkjet system, living cells were safely ejected onto culture disks. This microseeding technique with living cells has the potential to advance the field of tissue engineering.

TGF-β regulates isoform switching of FGF receptors and epithelial–mesenchymal transitionBoth TGF-β and FGF signalling regulate the epithelial–mesenchymal transition. Here, TGF-β is found to promote myofibroblast differentiation, while concomitant FGF pathway activation instead drives cells towards an invasive mesenchymal fate.