Depolarization and CaM kinase IV modulate NMDA receptor splicing through two essential RNA elements

Area of Science:

• Molecular Biology
• Neuroscience
• RNA Biology

Background:

• Alternative splicing regulates protein activity crucial for neuronal function.
• Signal-transduction pathways influencing alternative splicing remain incompletely understood.
• NMDAR1 exon 21 splicing controls NMDA receptor trafficking and is modulated by CaMK IV signaling.

Purpose of the Study:

• To characterize the regulation of NMDAR1 exon 21 splicing.
• To identify RNA elements mediating activity-dependent splicing repression.
• To investigate the role of CaMK IV in regulating alternative splicing.

Main Methods:

• Neuronal depolarization assays
• RNA element identification and characterization
• Heterologous exon splicing assays
• Site-directed mutagenesis
• Genome-wide motif search and RT-PCR validation

Main Results:

• Neuronal depolarization reversibly represses NMDAR1 exon 21 splicing.
• Two RNA elements within exon 21, CaRRE type 1 and CaRRE type 2, mediate this repression.
• Both exonic elements confer CaMK IV-dependent repression when introduced into other exons.
• Consensus sequences for these motifs were defined, and similar motifs were found in other depolarization-regulated exons.

Conclusions:

• Two novel RNA elements control activity-dependent alternative splicing in neurons.
• These elements link neuronal activity to changes in NMDAR1 splicing and potentially other transcripts.
• This work reveals a new mechanism for regulating neuronal function through coordinated alternative splicing events.