Alternative Splicing as a Driver of AMPAR Structural and Functional Diversity

Objective

AMPA-type glutamate receptors (AMPARs) mediate fast excitatory neurotransmission in the central nervous system and are key regulators of synaptic plasticity, learning, and memory. AMPARs are tetrameric receptors assembled from GluA1–4 subunits, whose molecular diversity is shaped by alternative splicing, RNA editing, and association with auxiliary proteins. The flip/flop isoforms of generated through alternative splicing and the mRNA editing significantly affect receptor kinetics, trafficking, and pharmacology. However, how these isoforms influence the structure and function of native AMPAR complexes remains poorly understood. This project aims to uncover how developmental isoform switching of AMPAR subunits shapes receptor structure and function, using cerebellar granule cells (CGCs) as a biological reference. CGCs are the most abundant neuronal type in the central nervous system and express a restricted set of AMPAR subunits—primarily GluA2 and GluA4—with developmentally regulated flip/flop isoform expression and associate mainly with TARP γ2 auxiliary proteins. These characteristics offer a simplified and physiologically relevant model to study defined AMPAR assemblies. We will combine transcriptomic profiling (RNA-seq) to characterize the developmental dynamics of flip/flop isoforms in CGCs; structural biology (cryo-EM) to resolve AMPAR A2/A4 receptor assemblies mimicking those found in CGCs; and electrophysiology (patch clamp) to examine the impact of isoform composition on receptor function. This integrative approach will shed light on how alternative splicing modulates AMPAR structure and activity in developmentally relevant contexts. The findings will enhance our understanding of receptor diversity in the brain and may support the rational design of isoform-selective AMPAR modulators for therapeutic purposes.