Splice Variants of the NR1 Subunit Differentially Induce NMDA Receptor-Dependent Gene Expression

• Published in: The Journal of neuroscience Vol. 26; no. 4; pp. 1065 - 1076
• Main Authors: Bradley, John, Carter, Sarah R, Rao, Vikram R, Wang, Jun, Finkbeiner, Steven
• Format: Journal Article
• Language: English
• Published: United States Soc Neuroscience 25.01.2006; Society for Neuroscience
• Subjects: Alternative Splicing; Animals; Calcium - analysis; Calcium Channels - metabolism; Calcium Signaling; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Calcium-Calmodulin-Dependent Protein Kinases - analysis; Calcium-Calmodulin-Dependent Protein Kinases - genetics; Cells, Cultured; Cerebral Cortex - cytology; Cerebral Cortex - embryology; Cyclic AMP Response Element-Binding Protein - metabolism; Gene Expression Regulation; Integrases - physiology; MAP Kinase Signaling System; Mice; N-Methylaspartate - pharmacology; Neurons - metabolism; Phosphorylation; Protein Interaction Mapping; Protein Processing, Post-Translational; Protein Structure, Tertiary; Receptors, N-Methyl-D-Aspartate - chemistry; Receptors, N-Methyl-D-Aspartate - genetics; Receptors, N-Methyl-D-Aspartate - physiology; Sequence Deletion; Signal Transduction; Structure-Activity Relationship; Transfection; Viral Proteins - physiology
• ISSN: 0270-6474; 1529-2401
• DOI: 10.1523/JNEUROSCI.3347-05.2006

Subunits of the NMDA receptor (NMDAR) associate with many postsynaptic proteins that substantially broaden its signaling capacity. Although much work has been focused on the signaling of NR2 subunits, little is known about the role of the NR1 subunit. We set out to elucidate the role of the C terminus of the NR1 subunit in NMDAR signaling. By introducing a C-terminal deletion mutant of the NR1 subunit into cultured neurons from NR1(-/-) mice, we found that the C terminus was essential for NMDAR inactivation, downstream signaling, and gene expression, but not for global increases in intracellular Ca2+. Therefore, whereas NMDARs can increase Ca2+ throughout the neuron, NMDAR-dependent signaling, both local and long range, requires coupling through the NR1 C terminus. Two major NR1 splice variants differ by the presence or absence of a C-terminal domain, C1, which is determined by alternative splicing of exon 21. Analysis of these two variants showed that removal of this domain significantly reduced the efficacy of NMDAR-induced gene expression without affecting receptor inactivation. Thus, the NR1 C terminus couples to multiple downstream signaling pathways that can be modulated selectively by RNA splicing.