Diacylglycerol production at the Golgi: regulation by Ca2+

Abstract

Protein kinase C and protein kinase D are potently activated by agonist‐evoked increases in diacylglycerol. Using live cell‐imaging probes for kinase activity, we have previously shown that both kinases are robustly active at the Golgi following stimulation of Gq‐coupled receptor signaling pathways, displaying activation signatures at the Golgi that are distinct from those at the plasma membrane. Here we address the mechanism by which signals received at the plasma membrane cause these two protein kinases to be activated at the Golgi. Using FRET‐based reporters to image diacylglycerol production, we show that Ca2+ is necessary and sufficient to transduce signals from the plasma membrane to the Golgi. First, chelation of intracellular Ca2+ prevents UTP‐dependent increases in diacylglycerol at the Golgi, but not plasma membrane. Second, raising intracellular Ca2+ by treating cells with thapsigargin induces diacylglycerol production at the Golgi. Thus, agonist‐evoked increases in intracellular Ca2+ cause increases in Golgi diacylglycerol, allowing this intracellular membrane to serve as a platform for signaling by protein kinases C and D.This work was supported by NIH GM43154 and NIH DK54441.