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Inflammatory mediators alter the astrocyte transcriptome and calcium signaling elicited by multiple G-protein-coupled receptors.

ABSTRACT: Inflammation features in CNS disorders such as stroke, trauma, neurodegeneration, infection, and autoimmunity in which astrocytes play critical roles. To elucidate how inflammatory mediators alter astrocyte functions, we examined effects of transforming growth factor-?1 (TGF-?1), lipopolysaccharide (LPS), and interferon-gamma (IFN?), alone and in combination, on purified, mouse primary cortical astrocyte cultures. We used microarrays to conduct whole-genome expression profiling, and measured calcium signaling, which is implicated in mediating dynamic astrocyte functions. Combinatorial exposure to TGF-?1, LPS, and IFN? significantly modulated astrocyte expression of >6800 gene probes, including >380 synergistic changes not predicted by summing individual treatment effects. Bioinformatic analyses revealed significantly and markedly upregulated molecular networks and pathways associated in particular with immune signaling and regulation of cell injury, death, growth, and proliferation. Highly regulated genes included chemokines, growth factors, enzymes, channels, transporters, and intercellular and intracellular signal transducers. Notably, numerous genes for G-protein-coupled receptors (GPCRs) and G-protein effectors involved in calcium signaling were significantly regulated, mostly down (for example, Cxcr4, Adra2a, Ednra, P2ry1, Gnao1, Gng7), but some up (for example, P2ry14, P2ry6, Ccrl2, Gnb4). We tested selected cases and found that changes in GPCR gene expression were accompanied by significant, parallel changes in astrocyte calcium signaling evoked by corresponding GPCR-specific ligands. These findings identify pronounced changes in the astrocyte transcriptome induced by TGF-?1, LPS, and IFN?, and show that these inflammatory stimuli upregulate astrocyte molecular networks associated with immune- and injury-related functions and significantly alter astrocyte calcium signaling stimulated by multiple GPCRs.

SUBMITTER: Hamby ME

PROVIDER: S-EPMC3518872 | biostudies-literature | 2012 Oct

REPOSITORIES: biostudies-literature

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Inflammatory mediators alter the astrocyte transcriptome and calcium signaling elicited by multiple G-protein-coupled receptors.

Hamby Mary E ME Coppola Giovanni G Ao Yan Y Geschwind Daniel H DH Khakh Baljit S BS Sofroniew Michael V MV

The Journal of neuroscience : the official journal of the Society for Neuroscience 20121001 42

Inflammation features in CNS disorders such as stroke, trauma, neurodegeneration, infection, and autoimmunity in which astrocytes play critical roles. To elucidate how inflammatory mediators alter astrocyte functions, we examined effects of transforming growth factor-β1 (TGF-β1), lipopolysaccharide (LPS), and interferon-gamma (IFNγ), alone and in combination, on purified, mouse primary cortical astrocyte cultures. We used microarrays to conduct whole-genome expression profiling, and measured cal ...[more]

PMID: 23077035

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Project description:CCAAT enhancer-binding protein (C/EBP)? regulates gene expression in multiple organ systems and cell types, including astrocytes in the central nervous system (CNS). Inflammatory stimuli, interleukin (IL)-1?, tumor necrosis factor-?, human immunodeficiency virus (HIV)-1 and lipopolysaccharide induce astrocyte C/EBP? expression. C/EBP? is detectable in brains of Alzheimer's disease (AD), Parkinson's disease (PD) and HIV-1-associated dementia (HAD) patients, yet little is known about how C/EBP? contributes to astrocyte gene regulation during neuroinflammation.The expression of 92 human inflammation genes was compared between IL-1?-treated primary human astrocytes and astrocytes transfected with C/EBP?-specific small interfering (si)RNA prior to IL-1? treatment for 12 h. Transcripts altered by>two-fold compared to control were subjected to one-way analysis of variance and Newman-Keuls post-test for multiple comparisons. Expression of two genes, cyclooxygenase-2 (COX-2) and bradykinin receptor B2 (BDKRB2) was further confirmed in additional human astrocyte donors. Astrocytes were treated with mitogen-activated protein kinase-selective inhibitors, then with IL-1? for 12 or 24 h followed by COX-2 and BDKRB2, expression analyses.IL-1? altered expression of 29 of 92 human inflammation genes by at least two-fold in primary human astrocytes in 12 h. C/EBP? knockdown affected expression of 17 out of 29 IL-1?-regulated genes by>25%. Two genes relevant to neuroinflammation, COX-2 and BDKRB2, were robustly decreased and increased, respectively, in response to C/EBP? knockdown, and expression was confirmed in two additional donors. COX-2 and BDKRB2 mRNA remained altered in siRNA-transfected astrocytes at 12, 24 or 72 h. Inhibiting p38 kinase (p38K) activation blocked IL-1?-induced astrocyte COX-2 mRNA and protein expression, but not IL-1?-induced astrocyte BDKRB2 expression. Inhibiting extracellular-regulated kinase (ERK)1/2 activation blocked IL-1?-induced BDKRB2 mRNA expression while increasing COX-2 expression.These data support an essential role for IL-1? in the CNS and identify new C/EBP? functions in astrocytes. Additionally, this work suggests p38K and ERK1/2 pathways may regulate gene expression in a complementary manner to fine tune the IL-1?-mediated astrocyte inflammatory response. Delineating a role for C/EBP? and other involved transcription factors in human astrocyte inflammatory response may lead to effective therapies for AD, PD, HAD and other neurological disorders.

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Inflammatory mediators alter the astrocyte transcriptome and calcium signaling elicited by multiple G-protein-coupled receptors.

Publications

Inflammatory mediators alter the astrocyte transcriptome and calcium signaling elicited by multiple G-protein-coupled receptors.

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