We recently discovered that RGS14 is a novel mediator of hippocampal-based learning/memory. We find that RGS14 is expressed predominantly in brain, specifically within dendrites/neurites of hippocampal neurons important for learning/memory (i.e. pyramidal cells of the CA1/CA2 region). Our novel mice lacking the RGS14 gene/protein (RGS14-KO) exhibit a marked enhancement of spatial learning/memory and novel-object recognition and of long-term potentiation (LTP) of postsynaptic neurotransmission in CA1 neurons. These findings strongly suggest that RGS14 regulates signaling events critically important for hippocampal-based learning/memory. However, the molecular and cellular actions of RGS14 in hippocampal neurons remain poorly defined. We find that RGS14 binds Ric8A, an unconventional guanine- nucleotide exchange factor activator for G1i, and also to inactive Gi11/3-GDP, active H-Ras and Rap2 and their effectors the Raf kinases. In cells, RGS14 co-localizes with its binding partners at the plasma membrane to inhibit stimulated Ras/Raf/Erk signaling. When complexed with its partners in cells, RGS14 is phosphorylated at unknown site(s) with unknown functional consequences. Of note, RGS14 partners H-Ras, Rap2, Gi and linked Erk pathways regulate """"""""synaptic plasticity"""""""" associated with learning/memory in hippocampal neurons including neurite outgrowth, dendritic remodeling, and trafficking of glutamate receptors. My working hypothesis is that RGS14 is a tightly regulated scaffolding protein that integrates unconventional Gi and H-Ras/Raf/MAPkinase signaling events important for synaptic plasticity involved with learning, memory and cognition in the hippocampus.
Our Specific Aims will be to:
Aim 1. Determine the protein/protein interactions and molecular mechanisms by which RGS14 integrates unconventional Ric8A/Gi1 and H-Ras/Rap2/Raf kinase signaling.
Aim 2 : Determine sites on RGS14 that are phosphorylated when complexed with Gi11/3, H- Ras or Rap2 in cells, the involved kinases, and how phosphorylation impacts RGS14 signaling.
Aim 3 : Determine roles for RGS14 in regulating molecular and physical markers of H- Ras/Raf/MAPkinase-directed synaptic plasticity in hippocampal neurons.
Aim 4 : Determine roles for RGS14 in regulating postsynaptic neurotransmission and linked behaviors that result from H-Ras/Raf/Erk-directed synaptic plasticity in the hippocampus Rap/MAPkinase signaling events and the morphology of primary hippocampal neurons. Impact: These studies will provide key insight about RGS14 as a novel regulator and integrator of neurotransmitter signaling events that modulate neuronal plasticity, learning and memory.
These studies will define novel molecular changes and underlying mechanism that occur in brain cells during normal physiological processes like learning and memory, and pathological processes such as Alzheimer's disease, other neurodegenerative diseases and epilepsy/seizures.
|Brown, Nicole E; Lambert, Nevin A; Hepler, John R (2016) RGS14 regulates the lifetime of G?-GTP signaling but does not prolong G?? signaling following receptor activation in live cells. Pharmacol Res Perspect 4:e00249|
|Gerber, Kyle J; Squires, Katherine E; Hepler, John R (2016) Roles for Regulator of G Protein Signaling Proteins in Synaptic Signaling and Plasticity. Mol Pharmacol 89:273-86|
|Brown, Nicole E; Blumer, Joe B; Hepler, John R (2015) Bioluminescence resonance energy transfer to detect protein-protein interactions in live cells. Methods Mol Biol 1278:457-65|
|Evans, Paul R; Dudek, Serena M; Hepler, John R (2015) Regulator of G Protein Signaling 14: A Molecular Brake on Synaptic Plasticity Linked to Learning and Memory. Prog Mol Biol Transl Sci 133:169-206|
|Brown, Nicole E; Goswami, Devrishi; Branch, Mary Rose et al. (2015) Integration of G protein ? (G?) signaling by the regulator of G protein signaling 14 (RGS14). J Biol Chem 290:9037-49|
|Evans, Paul R; Lee, Sarah E; Smith, Yoland et al. (2014) Postnatal developmental expression of regulator of G protein signaling 14 (RGS14) in the mouse brain. J Comp Neurol 522:186-203|
|Ghil, Sungho; McCoy, Kelly L; Hepler, John R (2014) Regulator of G protein signaling 2 (RGS2) and RGS4 form distinct G protein-dependent complexes with protease activated-receptor 1 (PAR1) in live cells. PLoS One 9:e95355|
|Hepler, John R (2014) G protein coupled receptor signaling complexes in live cells. Cell Logist 4:e29392|
|Zhao, Peishen; Nunn, Caroline; Ramineni, Suneela et al. (2013) The Ras-binding domain region of RGS14 regulates its functional interactions with heterotrimeric G proteins. J Cell Biochem 114:1414-23|
|Vellano, Christopher P; Brown, Nicole E; Blumer, Joe B et al. (2013) Assembly and function of the regulator of G protein signaling 14 (RGS14)·H-Ras signaling complex in live cells are regulated by G?i1 and G?i-linked G protein-coupled receptors. J Biol Chem 288:3620-31|
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