Baseline cytosolic Ca2+ oscillations derived from a non-endoplasmic reticulum Ca2+ store |
| |
Authors: | Missiaen L Van Acker K Parys J B De Smedt H Van Baelen K Weidema A F Vanoevelen J Raeymaekers L Renders J Callewaert G Rizzuto R Wuytack F |
| |
Institution: | Laboratorium voor Fysiologie, K.U. Leuven Campus Gasthuisberg O/N, Herestraat 49, Leuven B-3000, Belgium. Ludwig.Missiaen@med.kuleuven.ac.be |
| |
Abstract: | Cytosolic Ca(2+) oscillations can be due to cycles of release and re-uptake of internally stored Ca(2+). To investigate the nature of these Ca(2+) stores, we expressed the Pmr1 Ca(2+) pump of Caenorhabditis elegans in COS-1 cells and pretreated the cells with thapsigargin to prevent Ca(2+) uptake by the sarco(endo)plasmic reticulum Ca(2+)-ATPase. Pmr1 co-localized with the Golgi-specific 58K protein and was targeted to a Ca(2+) store that was less leaky for Ca(2+) than the endoplasmic reticulum and whose inositol trisphosphate receptors were less sensitive to inositol trisphosphate and ATP than those in the endoplasmic reticulum. ATP-stimulated Pmr1-overexpressing cells responded after a latency to extracellular Ca(2+) with a regenerative Ca(2+) signal, which could be prevented by caffeine. They also produced very stable ilimaquinone-sensitive baseline Ca(2+) spikes, even in the presence of thapsigargin. Such responses never occurred in non-transfected cells or in cells that overexpressed the type-1 sarco(endo)plasmic reticulum Ca(2+)-ATPase. Abortive Ca(2+) spikes also occurred in histamine-stimulated untransfected HeLa cells pretreated with thapsigargin, and they too were inhibited by ilimaquinone. We conclude that the Pmr1-induced Ca(2+) store, which probably corresponds to the Golgi compartment, can play a crucial role in setting up baseline Ca(2+) spiking. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|