There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
The ER-mitochondrial junction provides a local calcium signaling domain that is critical
for both matching energy production with demand and the control of apoptosis. Here,
we visualize ER-mitochondrial contact sites and monitor the localized [Ca(2+)] changes
([Ca(2+)](ER-mt)) using drug-inducible fluorescent interorganelle linkers. We show
that all mitochondria have contacts with the ER, but plasma membrane (PM)-mitochondrial
contacts are less frequent because of interleaving ER stacks in both RBL-2H3 and H9c2
cells. Single mitochondria display discrete patches of ER contacts and show heterogeneity
in the ER-mitochondrial Ca(2+) transfer. Pericam-tagged linkers revealed IP(3)-induced
[Ca(2+)](ER-mt) signals that exceeded 9 microM and endured buffering bulk cytoplasmic
[Ca(2+)] increases. Altering linker length to modify the space available for the Ca(2+)
transfer machinery had a biphasic effect on [Ca(2+)](ER-mt) signals. These studies
provide direct evidence for the existence of high-Ca(2+) microdomains between the
ER and mitochondria and suggest an optimal gap width for efficient Ca(2+) transfer.
2010 Elsevier Inc. All rights reserved.