| 17344311 |
Aromolaran AS, Zima AV, Blatter LA: Role of glycolytically generated ATP for CaMKII-mediated regulation of intracellular Ca2+ signaling in bovine vascular endothelial cells. Am J Physiol Cell Physiol. 2007 Jul;293(1):C106-18. Epub 2007 Mar 7.
The role of glycolytically generated ATP in Ca (2+)/calmodulin-dependent kinase II (CaMKII)-mediated regulation of intracellular Ca (2+) signaling was examined in cultured calf pulmonary artery endothelial (CPAE) cells. Exposure of cells (extracellular Ca (2+) concentration = 2 mM) to glycolytic inhibitors 2-deoxy-D-glucose (2-DG), pyruvate (pyr) + beta-hydroxybutyrate (beta-HB), or iodoacetic acid (IAA) caused an increase of intracellular Ca (2+) concentration ([Ca (2+)](i)). CaMKII inhibitors (KN-93, W-7) triggered a similar increase of [Ca (2+)](i). The rise of [Ca (2+)](i) was characterized by a transient spike followed by a small sustained plateau of elevated [Ca (2+)](i). In the absence of extracellular Ca (2+) 2-DG caused an increase in [Ca (2+)](i), suggesting that inhibition of glycolysis directly triggered release of Ca (2+) from intracellular endoplasmic reticulum (ER) Ca (2+) stores. The inositol-1,4,5-trisphosphate receptor (IP (3) R) inhibitor 2-aminoethoxydiphenyl borate abolished the KN-93- and 2-DG-induced Ca (2+) response. Ca (2+) release was initiated in peripheral cytoplasmic processes from which activation propagated as a [Ca (2+)](i) wave toward the central region of the cell. Focal application of 2-DG resulted in spatially confined elevations of [Ca (2+)](i). Propagating [Ca (2+)](i) waves were preceded by [Ca (2+)](i) oscillations and small, highly localized elevations of [Ca (2+)](i) (Ca (2+) puffs). Inhibition of glycolysis with 2-DG reduced the KN-93-induced Ca (2+) response, and vice versa during inhibition of CaMKII 2-DG-induced Ca (2+) release was attenuated. Similar results were obtained with pyr + beta-HB and W-7. Furthermore, 2-DG and IAA caused a rapid increase of intracellular Mg (2+) concentration, indicating a concomitant drop of cellular ATP levels. In conclusion, CaMKII exerts a profound inhibition of ER Ca (2+) release in CPAE cells, which is mediated by glycolytically generated ATP, possibly through ATP-dependent phosphorylation of the IP (3) R. |
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