Coordinate NF-kappaB and STAT1 activation promotes development of myeloid type 1 dendritic cells.

NF-kappaB and STAT1 are critically involved in the initiation of the inflammatory cascade. Using semi-automated imaging cytometry and fluorescent antibodies, we screened several factors for their ability to induce nuclear translocation of RelA/NF-kappaB and STAT1 in subsets of monocyte-derived dendritic cells (DC). Detailed kinetics and dose-response studies are presented for IL-1-, LPS-, CD40L-, IFN-gamma- and IFN-alpha-stimulated responses. The results are consistent with the notion that simultaneous activation of both STAT1 and NF-kappaB pathways at the initiation of differentiation culture is required for efficient priming of IL-12 production by DC. Maturation of DC led to characteristic NF-kappaB and STAT1 distribution and response patterns. During the resting stage, DC differentiated under the presence of IFN-gamma showed sustained STAT activation and remained responsive to LPS. By contrast, PGE2-supplemented DC could be characterized by negligible responses to LPS and IFN-gamma and a remarkable NF-kappaB response to CD40L. STAT1 pathway was suppressed in PGE2-supplemented cells. We conclude that the magnitude and temporal kinetics of the nuclear shift of STAT1 and NF-kappaB in myeloid DC are associated with IL-12p70 production and are dependent on the nature of the stimulating factors and the polarization state of cells.

Characterization of huJAM: evidence for involvement in cell-cell contact and tight junction regulation.

Cell-cell interactions of the mucosal epithelia are important for the maintenance and establishment of epithelial barrier function. During events of inflammation, such cell-cell interactions are often disrupted, resulting in a leaky epithelial barrier, which in turn can lead to various inflammatory and infective dysfunctions. Human junctional adhesion molecule (huJAM), found on the mucosal epithelia and vascular endothelia of many major organ systems, is a membrane glycoprotein which resolves to a doublet band of approximately 40 and approximately 37 kDa under SDS-PAGE analysis, representing differentially glycosylated forms of the same protein. huJAM was localized to the lateral membrane of Caco-2 cells (a human colonic epithelial cell line) monolayers, in an area basolateral of the epithelial tight junctions (TJ). Through functional and biochemical assays, we show huJAM to be able to homotypically associate and to participate in TJ restitution after trypsin-EDTA disruption. Furthermore, we also observed a migration of huJAM expression toward areas of cell-cell contacts during events of cell adhesion and monolayer formation. These qualities makes huJAM a likely player in the regulation of cell-cell contacts and the subsequent formation of TJs.

High-level production of recombinant proteins in CHO cells using a dicistronic DHFR intron expression vector.

We have constructed expression vectors for Chinese hamster ovary (CHO) cells that produce both selectable marker and recombinant cDNA from a single primary transcript via differential splicing. These vectors produce stable CHO cell clones that, when pooled, produce abundant amounts of secreted recombinant proteins compared with the amounts produced by conventional expression approaches that have selectable marker and the cDNA of interest under control of separate transcription units. Our vectors divert most of the transcript to product expression while linking it, at a fixed ratio, to dihydrofolate reductase (DHFR) expression to allow selection of stable transfectants. Pools of clones with increased expression of the product gene can be efficiently generated by selection in methotrexate. The high level of expression from pools allows convenient and rapid production of milligram amounts of recombinant proteins.