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Multiple sclerosis (MS) lesion formation is modulated by cytokines secreted within the central nervous system (CNS). Th1 lymphocytes and monocyte/macrophages (MM) likely induce lesion formation, whereas Th2 lymphocytes may inhibit formation. To explore the role of cytokines in MS lesions, we used gene arrays to investigate effects of cytokines representative of Th1 and Th2 cells and M/M on gene expression in cultured CNS glia; at 6 hr, all three increased expression of the interleukin-6 (IL-6) gene and decreased expression of the leptin receptor gene (obr), which mediates IL-6 production and other inflammatory responses. However, expression of a closely related gene, the interleukin-6 signal transducer or gp130 (IL-6st), showed no changes at 6 hr. IL-6st is an essential component of receptor complexes for IL-6 and other cytokines and growth factors that play critical roles in CNS inflammation, protection, and/or regeneration. To analyze expression of IL-6st and leptin receptor over time, we incubated rat CNS glial cultures for 6 hr to 5 days with the cytokines. All three cytokine mixtures down-regulated both IL-6st and leptin receptor mRNA and protein for up to 5 days. Immunocytochemical staining showed expression of both IL-6st and leptin receptor in all three types of glia, with lower IL-6st expression by 3 days. Down-regulation of IL-6st and leptin receptor in glia by cytokines could lead to decreased signaling by the proinflammatory IL-6 and reduced responses to regenerative/protective growth factors such as leukemia inhibitory factor and ciliary neurotrophic factor, potentially affecting the disease course in MS., ((c) 2009 Wiley-Liss, Inc.)

Understanding the regulation of cell death pathways is critical for protecting myelin-producing cells and their associated axons during injury resulting from multiple sclerosis and other degenerative diseases. The immortalized N20.1 oligodendroglial cell line provides a useful model for identifying mechanisms that can be exploited to attenuate cell death in myelin-producing cells and their precursors. In our hands, the N20.1 cell line exhibits different characteristics and morphology depending on temperature (permissive or non-permissive) and the presence of cAMP-elevating agents (Studzinski et al. [1998] Neurochem. Res. 23:435-441; Boullerne et al. [1999] J. Neurochem. 72:1050-1060; Studzinski et al. [1999] J. Neurosci. Res. 57:633-642). Our laboratory previously observed that NO donors cause primarily necrotic death in N20.1 cells grown at permissive temperature, but the NO donor SNP switched a portion of cell death to the apoptic pathway. We have continued our study of apoptotic death in these cells by comparing the effects of staurosporine, a known apoptotic agent, on cells grown at the permissive temperature ("undifferentiated") vs. the non-permissive temperature in the presence of forskolin ("differentiated"). Undifferentiated N20.1 cells exhibit maximal cell death after 24 hr of exposure to 50 nM staurosporine, whereas differentiated cells show delayed cell death, with maximal death seen after 48 hr. Pyknotic nuclei were observed in both growth conditions; however, differentiated cells were protected by caspase inhibitors, whereas undifferentiated cells were not. Increased ssDNA staining and DNA laddering were found following 24-hr staurosporine treatment in the differentiated cells only. These results support the conclusion that N20.1 cells can switch from necrotic to apoptotic cell death when cell division is slowed and cyclic AMP is elevated., (Copyright 2001 Wiley-Liss, Inc.)

Regulation of intracellular Ca(2+) (Ca(i)) plays a central role in cell survival, proliferation, and differentiation. We previously reported that immature oligodendroglia (OLs) are less susceptible than mature OLs to cell death following increases in Ca(i) (Benjamins and Nedelkoska [1995] Neurochem. Res. 21:471-479). The N20.1 murine OL cell line provides a model of an intermediate stage of OL maturation in which to study responses to Ca(i) increases with regard to viability, as well as the expression of mRNAs for myelin basic protein (MBP), proteolipid protein (PLP), DM-20, SCIP, and the immediate early genes ZIF268, c-fos, and c-jun. Cells were treated with the calcium ionophore A23187 or thapsigargin for 1, 3, and 18 hr. A23187 at 1.0 microM had no significant effect on cell detachment or death, whereas thapsigargin at 1.0 microM slightly increased both. With both agents, SCIP, MBP, and PLP mRNA levels were unaffected by 3 hr, but markedly reduced after 18 hours. DM-20 mRNA levels remained unchanged at both time points. With both agents, ZIF268, c-fos, and c-jun mRNA levels were unaffected after 1 hr; c-jun mRNA levels showed a significant increase after 3 hr of thapsigargin treatment. Thus, in N20.1 cells, increased calcium affects the IEG c-jun first, SCIP is coordinately decreased with MBP and PLP mRNAs at a later time point, and DM-20 message is under different regulation than PLP. J. Neurosci. Res. 57:633-642., (Copyright 1999 Wiley-Liss, Inc.)