The glia maturation factor (GMF), which was discovered in our laboratory, is a highly conserved protein predominantly localized in astrocytes. GMF is an intracellular regulator of stress-related signal transduction. We now report that the overexpression of GMF in astrocytes leads to the destruction of primary oligodendrocytes by interactions between highly purified cultures of astrocytes, microglia, and oligodendrocytes. We infected astrocytes with a replication-defective adenovirus carrying the GMF cDNA. The overexpression of GMF caused the activation of p38 MAP kinase and transcription factor NF-jB, as well as the induction of granulocytemacrophage colony-stimulating factor (GM-CSF) mRNA and protein in astrocytes. Small interfering RNA-mediated GMF knockdown completely blocked the GMF-dependent activation of p38 mitogen-activated protein kinase (MAPK), NF-jB, and enhanced expression of GM-CSF by astrocytes. Inhibition of p38 MAPK or NF-jB by specific inhibitors prevented GM-CSF production. The cell-free conditioned medium from overexpressing GMF astrocytes contained 320 ± 33 pg/mL of GM-CSF, which was responsible for enhanced production and secretion of TNF-a, IL-1b, IL-6, and IP-10 by microglia. Presence of these inflammatory cytokines in the conditioned medium from microglia efficiently destroyed oligodendrocytes in culture. These results suggest that GMF-induced production of GM-CSF in astrocytes is depending on p38 MAPK and NF-jB activation. The GM-CSF-dependent expression and secretion of inflammatory cytokine/chemokine, TNF-a, IL-1b, IL-6, and IP-10, is cytotoxic to oligodendrocytes, the myelinforming cells in the central nervous system, and as well as neurons. Our results suggest a novel pathway of GMF-initiated cytotoxicity of brain cells, and implicate its involvement in inflammatory diseases such as multiple sclerosis.

Using an in vivo RNA interference screen, we discovered that AGL, a glycogen debranching enzyme, has a biologically and statistically significant role in suppressing human cancer growth.

In the present study we report that a replication-defective adenovirus construct of GMF cDNA (GMF-V) induced overexpression of GMF protein in neuroblastoma (N18) cells caused cytotoxicity and loss of cell viability. A significant increase in activation of GSK-3β occurred after infection with GMF-V when compared with mock and lacZ controls. Overexpression of GMF also increased caspase-3 activity, an early marker of apoptosis. Depletion of GMF gene by introducing GMFspecific siRNA (GsiRNA) completely blocked both activation of GSK-3β and caspase-3 activation whereas a control scrambled siRNA (CsiRNA) had no effect. A cell-permeable peptide inhibitor of GSK-3β, and lithium completely prevented GMF-dependent activation of caspase-3. These results demonstrate that GSK-3 mediates activation of the death domain caspase by GMF overexpression. We also show that the phosphorylation of GSK-3-dependent site of Tau was a consequence of GMFoverexpression in N18 cells. Taken together our results imply that GMF is involved in the signaling leading to the activation of GSK-3β and caspase-3 in N18 cells and strongly suggest its involvement in neurodegeneration since, GSK-3β is known to hyperphosphorylate tau which is associated with the neurotoxicity of neurofibrillary tangles in Alzheimer's disease. KeywordsGlia maturation factor (GMF); neuroblastoma (N18) cells; glycogen synthase kinase-3β (GSK-3β);

Anaemia in rheumatoid arthritis (RA)

The therapeutic potential of interferon y (IFN y) in a number of disease states is still being explored, but progress is hampered by the lack of a suitable measure of in vivo biological activity. To assess the in vivo biological effects of recombinant human IFN y (rhIFN y), 14 patients were studied in a randomised, prospective, double blind, placebo controlled trial of this cytokine for the treatment of rheumatoid arthritis.