Proinflammatory cytokines released from microglia inhibit gap junctions in astrocytes: potentiation by β‐amyloid

Même, William; Calvo, Charles‐Félix; Froger, Nicolas; Ezan, Pascal; Amigou, Edwige; Koulakoff, Annette; Giaume, Christian

doi:10.1096/fj.05-4297fje

Cited by 183 publications

(142 citation statements)

References 46 publications

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“…Primary astrocyte cultures were prepared from the cortex of newborn (1-2 d of age) OF1 mice as described previously (Même et al, 2006). Briefly, cells were seeded into 100-mm-diameter plastic dishes (Nunc, Roskilde, Denmark) at the density of 3 ϫ 10 6 cells/dish in DMEM (Sigma-Aldrich, St-Louis, MO), supplemented with penicillin (5 U/ml), streptomycin (5 g/ml) (Invitrogen, Carlsbad, CA), and 10% FCS (Hyclone, Logan, UT).…”

Section: Culturesmentioning

confidence: 99%

“…MG-astrocyte cocultures were treated for 24 h with LPS at 10 ng/ml, which induced an MG activation (Même et al, 2006), and then used for experiments. Astrocyte cultures were treated with either CM* (diluted four times as the final concentration) or the mix of cytokines IL-1␤ and TNF-␣ (10 ng/ml for each; Roche Diagnostics, Indianapolis, MI) for 24 h and then used for experiments.…”

Section: Cell Treatmentsmentioning

confidence: 99%

“…Gap junction permeability was determined at room temperature (20 -22°C) using the scrape-loading/dye transfer (SL/DT) technique, as described previously (Même et al 2006), on either astrocyte cultures or MG-astrocyte cocultures. Briefly, experiments were performed by washing cells for 10 min in HEPES-buffered salt solution containing the fol-lowing (in mM): 140 NaCl, 5.5 KCl, 1.8 CaCl 2 , 1 MgCl 2 , 10 glucose, 10 HEPES, pH 7.4.…”

Section: Scrape Loading/dye Transfer Techniquementioning

confidence: 99%

“…The inhibition of astrocytic gap junctional communication (GJC), proceeded by the addition of resting MG on cultured astrocytes, has suggested a functional interaction between astrocytic GJC and MG (Rouach et al, 2002b). Recently, soluble factors secreted by activated MG were identified as responsible for the stronger inhibition of astrocyte-astrocyte GJC (Faustmann et al, 2003;Même et al, 2006). At least two proinflammatory cytokines, interleukin-1␤ (IL-1␤) and tumor necrosis factor-␣ (TNF-␣), were shown to be specifically involved in this inhibition (Même et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Recently, soluble factors secreted by activated MG were identified as responsible for the stronger inhibition of astrocyte-astrocyte GJC (Faustmann et al, 2003;Même et al, 2006). At least two proinflammatory cytokines, interleukin-1␤ (IL-1␤) and tumor necrosis factor-␣ (TNF-␣), were shown to be specifically involved in this inhibition (Même et al, 2006). Furthermore, astrocytic GJC inhibition was also described in other pathological conditions such as ischemia-reperfusion (Cotrina et al, 1998;Contreras et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Cx43 Hemichannels and Gap Junction Channels in Astrocytes Are Regulated Oppositely by Proinflammatory Cytokines Released from Activated Microglia

Retamal¹,

Froger²,

et al. 2007

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Astrocytes have a role in maintaining normal neuronal functions, some of which depend on connexins, protein subunits of gap junction channels and hemichannels. Under inflammatory conditions, microglia release cytokines, including interleukin-1␤ and tumor necrosis factor-␣, that reduce intercellular communication via gap junctions. Now, we demonstrate that either conditioned medium harvested from activated microglia or a mixture of these two cytokines enhances the cellular exchange with the extracellular milieu via Cx43 hemichannels. These changes in membrane permeability were not detected in astrocytes cultured from Cx43 knock-out mice and were abrogated by connexin hemichannel blockers, including La 3ϩ , mimetic peptides, and niflumic acid. Both the reduction in gap junctional communication and the increase in membrane permeability were mediated by a p38 mitogen-activated protein kinase-dependent pathway. However, the increase in membrane permeability, but not the gap junction inhibition, was rapidly reversed by the sulfhydryl reducing agent dithiothreitol, indicating that final regulatory mechanisms are different. Treatment with proinflammatory cytokines reduced the total and cell surface Cx43 levels, suggesting that the increase in membrane permeability was attributable to an increase in hemichannels activity. Indeed, unitary events of ϳ220 pS corresponding to Cx43 hemichannels were much more frequent in astrocytes treated with microglia conditioned medium than under control conditions. Finally, the effect of cytokines enhanced the uptake and reduced the intercellular diffusion of glucose, which might explain changes in the metabolic status of astrocytes under inflammatory conditions. Accordingly, this opposite regulation may affect glucose trafficking and certainly will modify the metabolic status of astrocytes involved in brain inflammation.

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Section: Culturesmentioning

confidence: 99%

Section: Cell Treatmentsmentioning

confidence: 99%

Section: Scrape Loading/dye Transfer Techniquementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Cx43 Hemichannels and Gap Junction Channels in Astrocytes Are Regulated Oppositely by Proinflammatory Cytokines Released from Activated Microglia

Retamal¹,

Froger²,

et al. 2007

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Electrophysiological In Vitro Study of Long‐Range Signal Transmission by Astrocytic Networks

Hastings,

Yu,

Huang

et al. 2023

Advanced Science

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Astrocytes are diverse brain cells that form large networks communicating via gap junctions and chemical transmitters. Despite recent advances, the functions of astrocytic networks in information processing in the brain are not fully understood. In culture, brain slices, and in vivo, astrocytes, and neurons grow in tight association, making it challenging to establish whether signals that spread within astrocytic networks communicate with neuronal groups at distant sites, or whether astrocytes solely respond to their local environments. A multi‐electrode array (MEA)‐based device called AstroMEA is designed to separate neuronal and astrocytic networks, thus allowing to study the transfer of chemical and/or electrical signals transmitted via astrocytic networks capable of changing neuronal electrical behavior. AstroMEA demonstrates that cortical astrocytic networks can induce a significant upregulation in the firing frequency of neurons in response to a theta‐burst charge‐balanced biphasic current stimulation (5 pulses of 100 Hz × 10 with 200 ms intervals, 2 s total duration) of a separate neuronal‐astrocytic group in the absence of direct neuronal contact. This result corroborates the view of astrocytic networks as a parallel mechanism of signal transmission in the brain that is separate from the neuronal connectome. Translationally, it highlights the importance of astrocytic network protection as a treatment target.

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The TLR3 ligand polyI:C downregulates connexin 43 expression and function in astrocytes by a mechanism involving the NF‐κB and PI3 kinase pathways

Zhao

Rivieccio

Lutz

et al. 2006

Glia

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Toll-like receptor 3 (TLR3) is a component of the innate immune response that responds to dsRNA viruses and virus replication intermediates. In this study we show that activation of astrocytes with the dsRNA mimetic polyinosinic-cytidylic acid (pI:C) results in loss of expression of connexin43 (Cx43) mRNA and protein while upregulating the expression of the ionotropic P2 receptor P2X(4)R. Analysis of the signaling pathways involved failed to demonstrate a role for the p38 MAP kinase, ERK, or JNK signaling pathways whereas an inhibitor of the PI3 kinase/Akt pathway effectively blocked the action of pI:C. Using adenoviral vectors containing a super-repressor of NF-kappaB (NF-kappaB SR) construct or a dominant negative interferon regulatory factor 3 (dnIRF3) construct showed that inhibition of both transcription factors also blocked the effects of pI:C. To explore the functional consequences of pI:C activation we used a pore-forming assay for P2X(4)R activity and a scrape loading assay for gap junction intercellular communication (GJIC). No pore-forming activity consistent with functional P2X(4)R expression was detected in either control or activated astrocytes. In contrast, robust Lucifer yellow transfer indicative of GJIC was detected in resting cells that was lost following pI:C activation. The dnIRF3 construct failed to restore GJIC whereas the NF-kappaB SR or the NF-kappaB inhibitor BAY11-7082 and the PI3K inhibitor LY294002 all significantly reversed the effect of pI:C on GJ connectivity. We conclude that activation of the innate immune response in astrocytes is associated with functional loss of GJIC through a pathway involving NF-kappaB and PI3 kinase.

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Proinflammatory cytokines released from microglia inhibit gap junctions in astrocytes: potentiation by β‐amyloid

Cited by 183 publications

References 46 publications

Cx43 Hemichannels and Gap Junction Channels in Astrocytes Are Regulated Oppositely by Proinflammatory Cytokines Released from Activated Microglia

Cx43 Hemichannels and Gap Junction Channels in Astrocytes Are Regulated Oppositely by Proinflammatory Cytokines Released from Activated Microglia

Electrophysiological In Vitro Study of Long‐Range Signal Transmission by Astrocytic Networks

The TLR3 ligand polyI:C downregulates connexin 43 expression and function in astrocytes by a mechanism involving the NF‐κB and PI3 kinase pathways

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