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Proinflammatory treatment of astrocytes with lipopolysaccharide results in augmented Ca2+ signaling through increased expression of VIA phospholipase A2 (iPLA2)

Authors: Mikhail, Strokin; Marina, Sergeeva; Georg, Reiser;

Proinflammatory treatment of astrocytes with lipopolysaccharide results in augmented Ca2+ signaling through increased expression of VIA phospholipase A2 (iPLA2)

Abstract

Many Ca2+-regulated intracellular processes are involved in the development of neuroinflammation. However, the changes of Ca2+ signaling in the brain under inflammatory conditions were hardly studied. ATP-induced Ca2+ signaling is a central event of signal transmission in astrocytic networks. We investigated primary astrocytes after proinflammatory stimulation with lipopolysaccharide (LPS; 100 ng/ml) for 6–24 h. We reveal that Ca2+ responses to purinergic ATP stimulation are significantly increased in amplitude and duration after stimulation with LPS. We detected that increased amplitudes of Ca2+ responses to ATP in LPS-treated astrocytes can be explained by substantial increase of Ca2+ load in stores in endoplasmic reticulum. The mechanism implies enhanced Ca2+ store refilling due to the amplification of capacitative Ca2+ entry. The reason for the increased duration of Ca2+ responses in LPS-treated cells is also the amplified capacitative Ca2+ entry. Next, we established that the molecular mechanism for the LPS-induced amplification of Ca2+ responses in astrocytes is increased expression and activity of VIA phospholipase A2 (VIA iPLA2). Indeed, both gene silencing with specific small interfering RNA and pharmacological inhibition of VIA iPLA2 with S-bromoenol lactone reduced the load of the Ca2+ stores and caused a decrease in the amplitudes of Ca2+ responses in LPS-treated astrocytes to values, which were comparable with those in untreated cells. Our findings highlight a novel regulatory role of VIA iPLA2 in development of inflammation in brain. We suggest that this enzyme might be a possible target for treatment of pathologies related to brain inflammation.

Keywords

Lipopolysaccharides, Endoplasmic Reticulum, Gene Expression Regulation, Enzymologic, Rats, Up-Regulation, Group VI Phospholipases A2, Animals, Newborn, Astrocytes, Animals, Calcium, Calcium Signaling, Gene Silencing, Gliosis, Inflammation Mediators, Cells, Cultured

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Powered by OpenAIRE graph
citations
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
27
Top 10%
Average
Top 10%