Nuclear Ca2+ plays a critical role in many cellular functions although its mode (s) of regulation is unclear. Recently, we have shown that the metabotropic glutamate receptor, mGlu5, mobilizes nuclear Ca2+ independent of cytosolic Ca2+ regulation. Immunocytochemical, ultrastructural, and subcellular fractionation techniques revealed that the metabotropic glutamate receptor, mGlu5, was localized to nuclear membranes in heterologous cells as well as midbrain and cortical neurons. Nuclear mGlu5 receptors expressed in heterologous cell types could bind agonist and isolated nuclei responded to agonist with rapid, oscillatory [Ca2+] elevations that were blocked by antagonist. Because these results challenge existing paradigms as to the role of intracellular receptors and have important ramifications in intracellular signaling, they are applicable to the purpose of the R21 mechanism. The goal of the current application is to establish a native, physiological system with which to test these novel concepts further. Because preliminary results indicate that mGluR5 receptors are expressed on both nuclear and plasma membranes in striatal cultures, these preparations will be used to examine the hypothesis that nuclear mGlu5 receptors can regulate nuclear Ca2+ in neurons. Specifically, cultures will be loaded with a calcium indicator whose spatio-temporal distribution will be analyzed in the confocal microscope. Following treatment with specific agonists and antagonists, cultures will be fixed, stained, and field re-located to determine whether nuclear oscillatory responses, if any, are associated with nuclear mGlu5 receptors. Striatal nuclei, isolated in situ, will be analyzed in a similar fashion. Subsequent experiments will address what ligand is activating nuclear receptors and how it is doing so. Given that mGlu5 receptors play pivotal roles in synaptic plasticity, neuronal development and modulation of synaptic transmission, the mechanisms by which they do so are of critical importance. Direct nuclear calcium regulation represents a novel signaling strategy by which intracellular receptors such as mGlu5 may play a pivotal role in generating and shaping intracellular Ca2+ signals ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21MH069646-02
Application #
6850769
Study Section
Molecular, Cellular and Developmental Neurosciences 2 (MDCN)
Program Officer
Asanuma, Chiiko
Project Start
2004-02-06
Project End
2006-01-31
Budget Start
2005-02-01
Budget End
2006-01-31
Support Year
2
Fiscal Year
2005
Total Cost
$137,700
Indirect Cost
Name
Washington University
Department
Neurosciences
Type
Schools of Medicine
DUNS #
068552207
City
Saint Louis
State
MO
Country
United States
Zip Code
63130
Jong, Yuh-Jiin I; O'Malley, Karen L (2017) Mechanisms Associated with Activation of Intracellular Metabotropic Glutamate Receptor, mGluR5. Neurochem Res 42:166-172
Sergin, Ismail; Jong, Yuh-Jiin I; Harmon, Steven K et al. (2017) Sequences within the C Terminus of the Metabotropic Glutamate Receptor 5 (mGluR5) Are Responsible for Inner Nuclear Membrane Localization. J Biol Chem 292:3637-3655
Jong, Yuh-Jiin I; O'Malley, Karen L (2015) Functional G protein-coupled receptors on nuclei from brain and primary cultured neurons. Methods Mol Biol 1234:113-21
Jong, Yuh-Jiin I; Sergin, Ismail; Purgert, Carolyn A et al. (2014) Location-dependent signaling of the group 1 metabotropic glutamate receptor mGlu5. Mol Pharmacol 86:774-85
Kumar, Vikas; Fahey, Paul G; Jong, Yuh-Jiin I et al. (2012) Activation of intracellular metabotropic glutamate receptor 5 in striatal neurons leads to up-regulation of genes associated with sustained synaptic transmission including Arc/Arg3.1 protein. J Biol Chem 287:5412-25
Jong, Yuh-Jiin I; Kumar, Vikas; O'Malley, Karen L (2009) Intracellular metabotropic glutamate receptor 5 (mGluR5) activates signaling cascades distinct from cell surface counterparts. J Biol Chem 284:35827-38
Kumar, Vikas; Jong, Yuh-Jiin I; O'Malley, Karen L (2008) Activated nuclear metabotropic glutamate receptor mGlu5 couples to nuclear Gq/11 proteins to generate inositol 1,4,5-trisphosphate-mediated nuclear Ca2+ release. J Biol Chem 283:14072-83
Jong, Yuh-Jiin I; Schwetye, Katherine E; O'Malley, Karen L (2007) Nuclear localization of functional metabotropic glutamate receptor mGlu1 in HEK293 cells and cortical neurons: role in nuclear calcium mobilization and development. J Neurochem 101:458-69
Jong, Yuh-Jiin I; Kumar, Vikas; Kingston, Ann E et al. (2005) Functional metabotropic glutamate receptors on nuclei from brain and primary cultured striatal neurons. Role of transporters in delivering ligand. J Biol Chem 280:30469-80