Depolarization and CaM kinase IV modulate NMDA receptor splicing through two essential RNA elements.
Alternative splicing controls the activity of many proteins important for neuronal excitation, but the signal-transduction pathways that affect spliced isoform expression are not well understood. One particularly interesting system of alternative splicing is exon 21 (E21) of the NMDA receptor 1 (NMDAR1 E21), which controls the trafficking of NMDA receptors to the plasma membrane and is repressed by Ca(++)/calmodulin-dependent protein kinase (CaMK) IV signaling. Here, we characterize the splicing of NMDAR1 E21. We find that E21 splicing is reversibly repressed by neuronal depolarization, and we identify two RNA elements within the exon that function together to mediate the inducible repression. One of these exonic elements is similar to an intronic CaMK IV-responsive RNA element (CaRRE) originally identified in the 3' splice site of the BK channel STREX exon, but not previously observed within an exon. The other element is a new RNA motif. Introduction of either of these two motifs, called CaRRE type 1 and CaRRE type 2, into a heterologous constitutive exon can confer CaMK IV-dependent repression on the new exon. Thus, either exonic CaRRE can be sufficient for CaMK IV-induced repression. Single nucleotide scanning mutagenesis defined consensus sequences for these two CaRRE motifs. A genome-wide motif search and subsequent RT-PCR validation identified a group of depolarization-regulated alternative exons carrying CaRRE consensus sequences. Many of these exons are likely to alter neuronal function. Thus, these two RNA elements define a group of co-regulated splicing events that respond to a common stimulus in neurons to alter their activity.
Lee
Ji-Ann
JA
Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, California, United States of America.
Xing
Yi
Y
Nguyen
David
D
Xie
Jiuyong
J
Lee
Christopher J
CJ
Black
Douglas L
DL
D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D016384:Consensus Sequence; D005091:Exons; D016678:Genome; D006801:Humans; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009474:Neurons / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D012322:RNA Precursors / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics* / Q000378:metabolism; D038621:Regulatory Sequences, Ribonucleic Acid; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
D002352:Carrier Proteins; C485668:GRIN1 protein, human; D009419:Nerve Tissue Proteins; D012322:RNA Precursors; D016194:Receptors, N-Methyl-D-Aspartate; D038621:Regulatory Sequences, Ribonucleic Acid; C517683:CAMK4 protein, human; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C517685:Camk4 protein, mouse