Cloning, biological characterization and high-level expression of rat interleukin-3 using recombinant adenovirus: description of a new splicing variant

Overexpression of glia maturation factor in astrocytes leads to immune activation of microglia through secretion of granulocyte-macrophage-colony stimulating factor

We infected a mixed culture of primary rat astrocytes and microglia with a replication-defective adenovirus carrying the rat glia maturation factor (GMF) cDNA. Affymetrix microarray analysis showed a big increase in the expression of several major histocompatibility complex (MHC) class II proteins along with interleukin-1beta (IL-1beta). Subsequent study using reverse transcription-polymerase chain reaction (RT-PCR) yielded the same results with the mixed culture, but not with pure astrocytes or pure microglia. We also noticed that the GMF/virus construct infected only astrocytes but not microglia. This led us to suspect that overexpression of GMF in astrocytes resulted in the secretion of an active substance that stimulated the microglia to express MHC II and IL-1beta. We identified this substance as granulocyte-macrophage-colony stimulating factor (GM-CSF). MHC II are unique to antigen-presenting cells such as microglia and monocytes. The results suggest that GMF in astrocytes can initiate a series of events, leading to immune activation in the nervous system, and implicates its involvement in autoimmune diseases such as multiple sclerosis.

Calcium-dependent activation of nuclear factor regulated by interleukin 3/adenovirus E4 promoter-binding protein gene expression by calcineurin/nuclear factor of activated T cells and calcium/calmodulin-dependent protein kinase signaling

An increase in the intracellular Ca(2+) concentration controls a diverse range of cell functions, including gene expression, apoptosis, adhesion, motility, and proliferation. We have investigated Ca(2+) regulation of gene expression in rat aortic smooth muscle cells. We found that the expression of nuclear factor regulated by interleukin 3 (NFIL3)/adenovirus E4 promoter-binding protein (E4BP4)/basic region/leucine zipper (bZIP) type of a transcription factor that has a very important function in cell survival, was activated by thapsigargin (TG). This activation was inhibited by chelation of extra- or intracellular Ca(2+), suggesting that the induction by TG was dependent on the elevation of [Ca(2+)](i). Specific inhibition of calcineurin or calcium/calmodulin-dependent protein kinase (CaM kinase) by chemical means impaired the TG-induced NFIL3/E4BP4 expression. Expression of dominant negative forms of calcineurin or nuclear factor of activated T cells (NFAT) inhibited the induction of NFIL3/E4BP4 mRNA by TG. These results suggest that intracellular Ca(2+) plays a critical role in regulating gene expression of NFIL3/E4BP4 by calcineurin/NFAT and CaM kinase signaling in vascular smooth muscle cells.