Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

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Dal Pra, I. et al.

Roles of Ca2+ and the Ca2+-sensing receptor (CASR) in the expression of inducible NOS (nitric oxide synthase)-2 and its BH4 (tetrahydrobiopterin)-dependent activation in cytokine-stimulated adult human astrocytes.

Since NO production by NOS-2 made by astrocytes activated by proinflammatory cytokines contributes to the killing of neurons in variously damaged human brains, knowing the mechanisms responsible for NOS-2 expression should contribute to developing effective therapeutics. The expression and activation of NOS-2 in normal adult human cerebral cortical astrocytes treated with three proinflammatory cytokines, IL-1beta, TNF-alpha, and IFN-gamma, are driven by two separable mechanisms. NOS-2 expression requires a burst of p38 MAPK activity, while the activation of the resulting enzyme protein requires MEK/ ERK-dependent BH4 (tetrahydrobiopterin) synthesis between 24 and 24.5 h after adding the cytokines to the culture medium. Here we show that NOS-2 expression in the activated astrocytes requires that the culture medium contain 1.8 mM Ca2+, but it is unaffected by inhibiting calcium-sensing receptors (CASRs) with NPS 89636. However, NOS-2 activation is inhibited by NPS 89626 during the MEK/ ERK-dependent stage between 24 and 24.5 h after adding the cytokines, and this inhibition can be overridden by exogenous BH4. Therefore, NOS-2 expression and the subsequent BH4-dependent NOS-2-activation in human astrocytes need 1.8 mM Ca2+ to be in the culture medium, while NOS-2 activation also needs functional CASRs between 24 and 24.5 h after cytokine addition. These findings raise the possibility that calcilytic drugs prevent NO-induced damage and death of human neurons.[1]

References

Roles of Ca2+ and the Ca2+-sensing receptor (CASR) in the expression of inducible NOS (nitric oxide synthase)-2 and its BH4 (tetrahydrobiopterin)-dependent activation in cytokine-stimulated adult human astrocytes. Dal Pra, I., Chiarini, A., Nemeth, E.F., Armato, U., Whitfield, J.F. J. Cell. Biochem. (2005) [Pubmed]

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