Learning from stargazin: the mouse, the phenotype and the unexpected

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• The stargazin gene (Cacng2) was identified in a mouse mutant exhibiting ataxia and epilepsy.
• Stargazin's relation to voltage-dependent calcium channel (VDCC) gamma-1 subunit suggested a role in epilepsy, but this remains unproven.
• Stargazin and its isoforms (gamma-3, -4, -8) are known to interact with AMPA-type glutamate receptors.

Purpose of the Study:

• To investigate the function of stargazin and its isoforms as auxiliary subunits of AMPA receptors.
• To elucidate the role of stargazin in regulating AMPA receptor trafficking and function in the brain.

Main Methods:

• Forward genetics in mice to identify the stargazin gene.
• Molecular and cellular biology techniques to study stargazin-AMPA receptor interactions.
• Electrophysiological recordings to assess AMPA receptor function.

Main Results:

• Stargazin and its isoforms primarily function as auxiliary subunits for AMPA-type glutamate receptors, not VDCCs.
• These interactions regulate crucial aspects of AMPA receptor function, including intracellular transport, synaptic targeting, and anchoring.
• Defects in stargazin's role with AMPA receptors are implicated in neurological disorders.

Conclusions:

• Stargazin and its isoforms are key regulators of AMPA receptor function in the brain.
• Their primary role is in modulating excitatory neurotransmission via AMPA receptors, not in VDCCs.
• Understanding stargazin's function offers insights into epilepsy and other neurological conditions.