Proinflammatory treatment of astrocytes with lipopolysaccharide results in augmented Ca2+ signaling through increased expression of VIA phospholipase A2 (iPLA2)
pmid: 21178110
Proinflammatory treatment of astrocytes with lipopolysaccharide results in augmented Ca2+ signaling through increased expression of VIA phospholipase A2 (iPLA2)
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.
- Lomonosov Moscow State University Russian Federation
- Otto-von-Guericke University Magdeburg Germany
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
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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