Human genetic variants disrupt RGS14 nuclear shuttling and regulation of LTP in hippocampal neurons.

• Authors: David Weinshenker, Emory University; Eric Ortlund, Emory University; Jason Schroeder, Emory University; John Hepler, Emory University; Christopher Scharer, Emory University; KE Squires, Department of Pharmacology and Chemical Biology, Emory University, Atlanta Georgia, USA.; KJ Gerber, Department of Pharmacology and Chemical Biology, Emory University, Atlanta Georgia, USA.; MC Tillman, Department of Biochemistry, Emory University, Atlanta Georgia, USA.; DJ Lustberg, Department of Human Genetics, Emory University, Atlanta Georgia, USA.; C Montañez-Miranda, Department of Pharmacology and Chemical Biology, Emory University, Atlanta Georgia, USA.; M Zhao, National Institute of Environmental Health Sciences, Research Triangle Park, Raleigh North Carolina, USA.; S Ramineni, Department of Pharmacology and Chemical Biology, Emory University, Atlanta Georgia, USA.; RN Saha, Department of Molecular & Cell Biology, University of California-Merced, Merced California, USA.; F-J Shu, Department of Pharmacology and Chemical Biology, Emory University, Atlanta Georgia, USA.; SM Dudek, National Institute of Environmental Health Sciences, Research Triangle Park, Raleigh North Carolina, USA.
• Journal Title: J Biol Chem
• Volume: Volume 296, Number
• Publisher: (publisher) | 2021-01, Pages 100024-100024
• Type of Work: Article
• Publisher DOI: http://doi.org/10.1074/jbc.RA120.016009
• Keywords: G protein; dendritic spine; genetic polymorphism; hippocampus; human genetics; neuron; nuclear receptor; nuclear translocation; regulator of G protein signaling (RGS); synaptic plasticity; Animals; Cell Nucleus; Hippocampus; Humans; Karyopherins; Long-Term Potentiation; Mice; Mutation; Neuronal Plasticity; Neurons; Protein Transport; RGS Proteins; Receptors, Cytoplasmic and Nuclear; Signal Transduction; Spatial Learning

Abstract

The human genome contains vast genetic diversity as naturally occurring coding variants, yet the impact of these variants on protein function and physiology is poorly understood. RGS14 is a multifunctional signaling protein that suppresses synaptic plasticity in dendritic spines of hippocampal neurons. RGS14 also is a nucleocytoplasmic shuttling protein, suggesting that balanced nuclear import/export and dendritic spine localization are essential for RGS14 functions. We identified genetic variants L505R (LR) and R507Q (RQ) located within the nuclear export sequence (NES) of human RGS14. Here we report that RGS14 encoding LR or RQ profoundly impacts protein functions in hippocampal neurons. RGS14 membrane localization is regulated by binding Gαi-GDP, whereas RGS14 nuclear export is regulated by Exportin 1 (XPO1). Remarkably, LR and RQ variants disrupt RGS14 binding to Gαi1-GDP and XPO1, nucleocytoplasmic equilibrium, and capacity to inhibit long-term potentiation (LTP). Variant LR accumulates irreversibly in the nucleus, preventing RGS14 binding to Gαi1, localization to dendritic spines, and inhibitory actions on LTP induction, while variant RQ exhibits a mixed phenotype. When introduced into mice by CRISPR/Cas9, RGS14-LR protein expression was detected predominantly in the nuclei of neurons within hippocampus, central amygdala, piriform cortex, and striatum, brain regions associated with learning and synaptic plasticity. Whereas mice completely lacking RGS14 exhibit enhanced spatial learning, mice carrying variant LR exhibit normal spatial learning, suggesting that RGS14 may have distinct functions in the nucleus independent from those in dendrites and spines. These findings show that naturally occurring genetic variants can profoundly alter normal protein function, impacting physiology in unexpected ways.