Calcium transduces plasma membrane receptor signals to produce diacylglycerol at Golgi membranes.
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 shown that both kinases are robustly activated at the Golgi following stimulation of G(q)-coupled receptor signaling pathways, displaying activation signatures at the Golgi that are distinct from those at the plasma membrane. Here we report that Ca(2+) is the mediator that allows signals received at the plasma membrane to activate these two protein kinases at the Golgi. Specifically, using fluorescence resonance energy transfer-based reporters to image diacylglycerol production, we show that Ca(2+) is necessary and sufficient to elevate diacylglycerol levels at the Golgi. First, raising intracellular Ca(2+) by treating cells with thapsigargin induces diacylglycerol production at the Golgi. Second, chelation of intracellular Ca(2+) prevents UTP-stimulated increases in diacylglycerol at the Golgi. Thus, agonist-evoked increases in intracellular Ca(2+) cause increases in Golgi diacylglycerol, allowing this intracellular membrane to serve as a platform for signaling by protein kinases C and D.
Department of Pharmacology, University of California at San Diego, La Jolla, California 92093, USA.
Maya T
MT
Kunkel
Alexandra C
AC
Newton
D000818:Animals; D019556:COS Cells; D020013:Calcium Signaling; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002522:Chlorocebus aethiops; D004075:Diglycerides / Q000096:biosynthesis*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D031541:Fluorescence Resonance Energy Transfer; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism*; D010711:Phosphatidate Phosphatase / Q000037:antagonists & inhibitors; D054801:Phosphoinositide Phospholipase C / Q000037:antagonists & inhibitors; D011493:Protein Kinase C / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*
D004075:Diglycerides; D004791:Enzyme Inhibitors; D043562:Receptors, G-Protein-Coupled; C089212:protein kinase D; D011493:Protein Kinase C; D010711:Phosphatidate Phosphatase; D054801:Phosphoinositide Phospholipase C