Reversible Translocation and Activity-Dependent Localization of the Calcium-Myristoyl Switch Protein VILIP-1 to Different Membrane Compartments in Living Hippocampal Neurons

• Published in: The Journal of neuroscience Vol. 22; no. 17; pp. 7331 - 7339
• Main Authors: Spilker, Christina, Dresbach, Thomas, Braunewell, Karl-Heinz
• Format: Journal Article
• Language: English
• Published: United States Soc Neuroscience 01.09.2002; Society for Neuroscience
• Subjects: Animals; Calcium - metabolism; Calcium-Binding Proteins - genetics; Calcium-Binding Proteins - metabolism; Cell Compartmentation - physiology; Cell Line; COS Cells; Green Fluorescent Proteins; Hippocampus - metabolism; Internet; Intracellular Fluid - metabolism; Intracellular Membranes - metabolism; Luminescent Proteins - genetics; Mice; Microscopy, Fluorescence; Microscopy, Video; Myristates - metabolism; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Neurocalcin; Neurons - cytology; Neurons - metabolism; Protein Transport - physiology; Rats; Receptors, Calcium-Sensing; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Signal Transduction - physiology; Transfection
• ISSN: 0270-6474; 1529-2401
• DOI: 10.1523/jneurosci.22-17-07331.2002

Visinin-like protein-1 (VILIP-1) belongs to the family of neuronal calcium sensor (NCS) proteins, a neuronal subfamily of EF-hand [corrected] calcium-binding proteins that are myristoylated at their N termini. NCS proteins are discussed to play roles in calcium-dependent signal transduction of physiological and pathological processes in the CNS. The calcium-dependent membrane association, the so-called calcium-myristoyl switch, localizes NCS proteins to a distinct cellular signaling compartment and thus may be a critical mechanism for the coordinated regulation of signaling cascades. To study whether the biochemically defined calcium-myristoyl switch of NCS proteins can occur in living neuronal cells, the reversible and stimulus-dependent translocation of green fluorescent protein (GFP)-tagged VILIP-1 to subcellular targets was examined by fluorescence microscopy in transfected cell lines and hippocampal primary neurons. In transiently transfected NG108-15 and COS-7 cells, a translocation of diffusely distributed VILIP-1-GFP but not of myristoylation-deficient VILIP-1-GFP to the plasma membrane and to intracellular targets, such as Golgi membranes, occurred after raising the intracellular calcium concentration with a calcium ionophore. The observed calcium-dependent localization was completely reversed after depletion of intracellular calcium by EGTA. Interestingly, a fast and reversible translocation of VILIP-1-GFP and translocation of endogenous VILIP-1 to specialized membrane structures was also observed after a depolarizing stimulus or activation of glutamate receptors in hippocampal neurons. These results show for the first time the reversibility and stimulus-dependent occurrence of the calcium-myristoyl switch in living neurons, suggesting a physiological role as a signaling mechanism of NCS proteins, enabling them to activate specific targets localized in distinct membrane compartments.