DYRK1A-mediated phosphorylation of GluN2A at Ser1048 regulates the surface expression and channel activity of GluN1/GluN2A receptors

Abstract

N-methyl-D-aspartate glutamate receptors (NMDARs) play a pivotal role in neural development and synaptic plasticity, as well as in neurological disease. Since NMDARs exert their function at the cell surface, their density in the plasma membrane is finely tuned by a plethora of molecules that regulate their production, trafficking, docking and internalization in response to external stimuli. In addition to transcriptional regulation, the density of NMDARs is also influenced by post-translational mechanisms like phosphorylation, a modification that also affects their biophysical properties. We previously described the increased surface expression of GluN1/GluN2A receptors in transgenic mice overexpressing the Dual specificity tyrosine-phosphorylation-regulated kinase 1A (DYRK1A), suggesting that DYRK1A regulates NMDARs. Here we have further investigated whether the density and activity of NMDARs were modulated by DYRK1A phosphorylation. Accordingly, we show that endogenous DYRK1A is recruited to GluN2A-containing NMDARs in the adult mouse brain, and we identify a DYRK1A phosphorylation site at Ser1048 of GluN2A, within its intracellular C-terminal domain. Mechanistically, the DYRK1A-dependent phosphorylation of GluN2A at Ser1048 hinders the internalization of GluN1/GluN2A, causing an increase of surface GluN1/GluN2A in heterologous systems, as well as in primary cortical neurons. Furthermore, GluN2A phosphorylation at Ser1048 increases the current density and potentiates the gating of GluN1/GluN2A receptors. We conclude that DYRK1A is a direct regulator of NMDA receptors and we propose a novel mechanism for the control of NMDAR activity in neurons.

Vascular defects ofDYRK1Aknockouts are ameliorated by modulating calcium signaling in zebrafish

“…An underlying mechanism by which dyrk1aa regulates the calcium signaling in vascular formation is not yet clear. DYRK1A may affect Ca 2+ flux directly as in the case of GluN2Acontaining NMDARs (N-methyl-D-aspartate glutamate receptors) phosphorylation by DYRK1A, leading to the elevation of their density on the membrane, and eventually on neurological dysfunction (Grau et al, 2014). Alternatively, Dyrk1a may indirectly influence Ca 2+ signaling by phosphorylating mediators that determine the expression or activity of calcium-dependent effectors, similar to myocardial pathology, in which phosphorylation of Alternative Splicing Factor (ASF) by Dyrk1a increases the expression of Ca 2+ /calmodulindependent protein kinase II  (CaMKII (He et al, 2015)Because Dyrk1a is likely to be functional both in the nucleus and in the cytoplasm based on its ubiquitous localization at the cellular level (Marti et al, 2003), it may directly or indirectly regulate membrane-bound ion channels near the cell membrane (similar to GluN2A phosphorylation), intracellular signaling molecules in the cytoplasm, or transcription factors in the nucleus, eventually maintaining the Ca 2+ homeostasis of cells.…”

Cell-Specific Regulation of N-Methyl-D-Aspartate Receptor Maturation by Mecp2 in Cortical Circuits

“…Thus, the delay of NMDAR maturation in pyramidal cells could be due to a decrease in the activity-dependent phosphorylation of GluN2B and, thus, retention at the synapse. It is also possible that the acceleration in NMDAR maturation in PV cells could be due to their higher basal excitability in the Mecp2 -KO (27), resulting in more active removal of GluN2B from the synapses and insertion and/or post-translational modification of GluN2A subunits (35,36). It is not known, however, whether the NMDAR subunit switch in PV cells is mediated by activity as in pyramidal cells, nor whether the same post-translational modifications to the GluN2 subunits occur in interneuronal subtypes.…”

DYRK1A, a Dosage-Sensitive Gene Involved in Neurodevelopmental Disorders, Is a Target for Drug Development in Down Syndrome

“…et al, 2014 ). Moreover, DYRK1A phosphorylation of GRIN2A modifies the biophysical properties of GRIN1/GRIN2A, two subunits of N -methyl- D -aspartate receptors (NMDAR) and controls NMDAR activity in neurons, which are involved in neural development, survival, synaptic plasticity and memory processes ( Grau et al, 2014 ).…”