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Ito H, Yamamoto N, Arima H, Hirate H, Morishima T, Umenishi F, Tada T, Asai K, Katsuya H, Sobue K: Interleukin-1beta induces the expression of aquaporin-4 through a nuclear factor-kappaB pathway in rat astrocytes. J Neurochem. 2006 Oct;99(1):107-18. Interleukin (IL)-1beta is known to play a role in the formation of brain edema after various types of injury. Aquaporin (AQP) 4 is also reported to be involved in the progression of brain edema. We tested the hypothesis that AQP4 is induced in response to IL-1beta. We found that expression of AQP4 mRNA and protein was significantly up-regulated by IL-1beta in cultured rat astrocytes, and that intracerebroventricular administration of IL-1beta increased the expression of AQP4 protein in rat brain. The effects of IL-1beta on induction of AQP4 were concentration and time dependent. The effects of IL-1beta on AQP4 were mediated through IL-1beta receptors because they were abolished by co-incubation with IL-1 receptor antagonist. It appeared that IL-1beta increased the level of AQP4 mRNA without involvement of de novo protein synthesis because cycloheximide, a protein synthesis inhibitor, did not inhibit the effects of IL-1beta. Inhibition of the nuclear factor-kappaB (NF-kappaB) pathway blocked the induction of AQP4 by IL-1beta in a concentration-dependent manner. These findings show that IL-1beta induces expression of AQP4 through a NF-kappaB pathway without involvement of de novo protein synthesis in rat astrocytes. |
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