Coexpressed auxiliary subunits exhibit distinct modulatory profiles on AMPA receptor function

Area of Science:

• Neuroscience
• Molecular Biology
• Cell Biology

Background:

• Auxiliary subunits critically modulate AMPA receptor (AMPAR) function, including gating and surface trafficking.
• TARP γ-8 and CKAMP44 are highly expressed in dentate gyrus (DG) granule cells, suggesting a significant role in this neuronal population.

Purpose of the Study:

• To investigate the distinct and combined roles of TARP γ-8 and CKAMP44 in modulating AMPAR properties and synaptic plasticity in DG granule cells.
• To determine the necessity of these auxiliary subunits for AMPAR surface targeting and their contribution to different forms of plasticity.

Main Methods:

• Electrophysiological recordings to assess receptor deactivation, desensitization, and synaptic plasticity.
• Biochemical assays to investigate AMPAR surface trafficking and subunit co-assembly.

Main Results:

• TARP γ-8 and CKAMP44 differentially affect AMPAR deactivation and desensitization, leading to distinct short-term plasticity modulation.
• Long-term plasticity (LTP) in DG granule cells requires TARP γ-8, but not CKAMP44.
• Coexpression of TARP γ-8 and CKAMP44 is essential for efficient AMPAR surface targeting in DG granule cells.
• Evidence suggests that CKAMP44 and TARP γ-8 can form complexes within the same AMPAR.

Conclusions:

• TARP γ-8 and CKAMP44 play crucial, yet distinct, roles in regulating AMPAR function, surface expression, and plasticity in DG granule cells.
• The interplay between these auxiliary subunits is vital for proper AMPAR trafficking and synaptic function, impacting both short-term and long-term synaptic modifications.