Activation of astrocyte intracellular signaling pathways by interleukin‐1 in rat primary striatal cultures

Abstract

The striatum has been implicated as the site of action mediating neurotoxic effects of interleukin-1 (IL-1) during ischemia. However, the molecular mechanisms underlying these events have yet to be fully addressed. In the present study, primary cultures of rat striatal cells were used as a model for the study of IL-1 signaling pathways in the striatum. Immunocytochemical analyses revealed that these cultures consisted of a mixture of neurones and astrocytes and demonstrated expression of the IL-1 type I receptor (IL-1RI) on both cell types. Treatment with IL-1 (3 units/ml) for 10 min increased phosphorylation of p38 MAP kinase in striatal cells. The endogenous IL-1RI inhibitor IL-1Ra (24 ng/ml) and the p38 MAP kinase inhibitor SB203580 (10 nM) both inhibited this response. Analysis of the effects of IL-1 on nuclear translocation of the transcription factor NF-kB revealed that NF-kB became activated in a time-dependent manner. Immunocytochemistry revealed that IL-1 stimulated p38 phosphorylation and NF-kB translocation in astrocytes only. TaqMan real-time quantitative PCR analysis revealed that IL-1 stimulated gene expression of tumor necrosis factor-alpha (TNF) in striatal cultures. The p38 MAP kinase inhibitor SB203580 failed to inhibit the effects of IL-1 on NF-kB translocation or gene transcription. These studies have demonstrated significant aspects of the IL-1 signaling cascade in cultured striatum. Of particular interest is the finding that IL-1 stimulated activation of p38 MAP kinase and NF-kB in striatal astrocytes exclusively.

p38/SAPK2 controls gap junction closure in astrocytes

“…A proteomic analysis of astrocytic phosphoproteins affected by SB203580 in comparison with the ERK/MAPK inhibitor PD98059, done after 2D-SDS-PAGE analysis, revealed specific and essentially nonoverlapping maps of inhibition. This is in good agreement with a recently reported SB203580 inhibition of the IL-1␤-induced p38/ SAPK2 activation in striatal astrocytes, not affecting the cytokine-induced NF-B translocation and gene transcription (Dunn et al, 2002). SB203580 appears thus to affect p38/SAPK2 activity in a specific manner in our experimental conditions.…”

Astrocyte function and role in motor neuron disease: A future therapeutic target?

“…Astrocytes may return to a quiescent state or undergo programmed cell death. NFjB nuclear translocation is seen in apoptotic, as well as reactive astrocytes (Dunn et al, 2002), suggesting that apoptosis of astrocytes is the normal pathway for the elimination of harmful reactive astrocytes. The failure of clearance of reactive astrocytes by apoptosis may result in greater neuronal toxicity because reactive astrocytes are less able to maintain CNS homeostasis (Takuma et al, 2004).…”

Extracellular ATP Selectively Upregulates Ecto-Nucleoside Triphosphate Diphosphohydrolase 2 and Ecto-5′-Nucleotidase by Rat Cortical Astrocytes In Vitro

“…Specifically, by acting at P2X7 receptor (Di Virgilio, 2007), ATP stimulates assembly of NOD-like receptor protein (Chakraborty et al 2010;Minkiewicz et al 2013) and activates caspase-1 which results in processing and secretion of IL-1β (Bours et al 2011). This cytokine appears to be essential for astrocyte activation and proliferation (Herx and Yong 2001;Dunn et al 2002;John et al 2004) as well as production and release of other proinflammatory cytokines (Liu et al 2000;Cahill and Rogers 2008), including tumor necrosis factor alpha (TNF-α) (Kucher and Neary, 2005;Zou et al 2012).…”