Caldendrin-Jacob: a protein liaison that couples NMDA receptor signalling to the nucleus.

• Main Authors: Daniela C Dieterich, Anna Karpova, Marina Mikhaylova, Irina Zdobnova, Imbritt König, Marco Landwehr, Martin Kreutz, Karl-Heinz Smalla, Karin Richter, Peter Landgraf, Carsten Reissner, Tobias M Boeckers, Werner Zuschratter, Christina Spilker, Constanze I Seidenbecher, Craig C Garner, Eckart D Gundelfinger, Michael R Kreutz
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2008-02-01
• Series: PLoS Biology
• Online Access: http://europepmc.org/articles/PMC2253627?pdf=render
• ISSN: 1544-9173; 1545-7885

NMDA (N-methyl-D-aspartate) receptors and calcium can exert multiple and very divergent effects within neuronal cells, thereby impacting opposing occurrences such as synaptic plasticity and neuronal degeneration. The neuronal Ca2+ sensor Caldendrin is a postsynaptic density component with high similarity to calmodulin. Jacob, a recently identified Caldendrin binding partner, is a novel protein abundantly expressed in limbic brain and cerebral cortex. Strictly depending upon activation of NMDA-type glutamate receptors, Jacob is recruited to neuronal nuclei, resulting in a rapid stripping of synaptic contacts and in a drastically altered morphology of the dendritic tree. Jacob's nuclear trafficking from distal dendrites crucially requires the classical Importin pathway. Caldendrin binds to Jacob's nuclear localization signal in a Ca2+-dependent manner, thereby controlling Jacob's extranuclear localization by competing with the binding of Importin-alpha to Jacob's nuclear localization signal. This competition requires sustained synapto-dendritic Ca2+ levels, which presumably cannot be achieved by activation of extrasynaptic NMDA receptors, but are confined to Ca2+ microdomains such as postsynaptic spines. Extrasynaptic NMDA receptors, as opposed to their synaptic counterparts, trigger the cAMP response element-binding protein (CREB) shut-off pathway, and cell death. We found that nuclear knockdown of Jacob prevents CREB shut-off after extrasynaptic NMDA receptor activation, whereas its nuclear overexpression induces CREB shut-off without NMDA receptor stimulation. Importantly, nuclear knockdown of Jacob attenuates NMDA-induced loss of synaptic contacts, and neuronal degeneration. This defines a novel mechanism of synapse-to-nucleus communication via a synaptic Ca2+-sensor protein, which links the activity of NMDA receptors to nuclear signalling events involved in modelling synapto-dendritic input and NMDA receptor-induced cellular degeneration.