Endothelial Pannexin 1 Channels Control Inflammation by Regulating Intracellular Calcium.
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ABSTRACT: The proinflammatory cytokine IL-1? is a significant risk factor in cardiovascular disease that can be targeted to reduce major cardiovascular events. IL-1? expression and release are tightly controlled by changes in intracellular Ca2+ ([Ca2+]i), which has been associated with ATP release and purinergic signaling. Despite this, the mechanisms that regulate these changes have not been identified. The pannexin 1 (Panx1) channels have canonically been implicated in ATP release, especially during inflammation. We examined Panx1 in human umbilical vein endothelial cells following treatment with the proinflammatory cytokine TNF-?. Analysis by whole transcriptome sequencing and immunoblot identified a dramatic increase in Panx1 mRNA and protein expression that is regulated in an NF-?B-dependent manner. Furthermore, genetic inhibition of Panx1 reduced the expression and release of IL-1?. We initially hypothesized that increased Panx1-mediated ATP release acted in a paracrine fashion to control cytokine expression. However, our data demonstrate that IL-1? expression was not altered after direct ATP stimulation in human umbilical vein endothelial cells. Because Panx1 forms a large pore channel, we hypothesized it may permit Ca2+ diffusion into the cell to regulate IL-1?. High-throughput flow cytometric analysis demonstrated that TNF-? treatments lead to elevated [Ca2+]i, corresponding with Panx1 membrane localization. Genetic or pharmacological inhibition of Panx1 reduced TNF-?-associated increases in [Ca2+]i, blocked phosphorylation of the NF-?B-p65 protein, and reduced IL-1? transcription. Taken together, the data in our study provide the first evidence, to our knowledge, that [Ca2+]i regulation via the Panx1 channel induces a feed-forward effect on NF-?B to regulate IL-1? synthesis and release in endothelium during inflammation.
SUBMITTER: Yang Y
PROVIDER: S-EPMC7336877 | biostudies-literature | 2020 Jun
REPOSITORIES: biostudies-literature
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