Phosphatidylinositol 4,5-bisphosphate optical uncaging potentiates exocytosis.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 29068313.
- Also identified by DOI 10.7554/eLife.30203 and PMC identifier 5711374.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Phosphatidylinositol-4,5-bisphosphate [PI(4,5)P<sub>2</sub>] is essential for exocytosis. Classical ways of manipulating PI(4,5)P<sub>2</sub> levels are slower than its metabolism, making it difficult to distinguish effects of PI(4,5)P<sub>2</sub> from those of its metabolites. We developed a membrane-permeant, photoactivatable PI(4,5)P<sub>2</sub>, which is loaded into cells in an inactive form and activated by light, allowing sub-second increases in PI(4,5)P<sub>2</sub> levels. By combining this compound with electrophysiological measurements in mouse adrenal chromaffin cells, we show that PI(4,5)P<sub>2</sub> uncaging potentiates exocytosis and identify synaptotagmin-1 (the Ca<sup>2+</sup> sensor for exocytosis) and Munc13-2 (a vesicle priming protein) as the relevant effector proteins. PI(4,5)P<sub>2</sub> activation of exocytosis did not depend on the PI(4,5)P<sub>2</sub>-binding CAPS-proteins, suggesting that PI(4,5)P<sub>2</sub> uncaging may bypass CAPS-function. Finally, PI(4,5)P<sub>2</sub> uncaging triggered the rapid fusion of a subset of readily-releasable vesicles, revealing a rapid role of PI(4,5)P<sub>2</sub> in fusion triggering. Thus, optical uncaging of signaling lipids can uncover their rapid effects on cellular processes and identify lipid effectors.
Medical subject headings
- Exocytosis
- Phosphatidylinositol 4,5-Diphosphate