Synaptotagmin-3 interactions with GluA2 mediate brain damage and impair functional recovery in stroke

Area of Science:

• Neuroscience
• Molecular Biology
• Cell Biology

Background:

• Synaptotagmin III (Syt3) is a calcium-dependent protein crucial for synaptic plasticity and receptor endocytosis.
• Syt3 is primarily located in synaptic plasma membranes.

Purpose of the Study:

• To investigate the role of Syt3 in ischemia/reperfusion (I/R) brain injury.
• To elucidate the molecular mechanisms by which Syt3 influences neurological outcomes after I/R injury.

Main Methods:

• Studied Syt3 expression in the penumbra after I/R injury.
• Utilized Syt3 knockdown and overexpression models.
• Examined Syt3-GluA2 interactions and GluA2 surface expression.
• Investigated the formation of calcium-permeable AMPA receptors (CP-AMPARs).
• Employed CP-AMPAR antagonists and Syt3-GluA2 complex dissociation peptides.
• Analyzed Syt3 knockout mice in cerebral ischemia models.

Main Results:

• Syt3 is upregulated in the penumbra following I/R injury.
• Syt3 knockdown confers protection against I/R injury, enhancing motor function recovery and inhibiting cognitive decline.
• Syt3 overexpression yields opposite effects.
• I/R injury increases Syt3-GluA2 interactions, reduces surface GluA2 expression, and promotes CP-AMPAR formation.
• CP-AMPAR antagonism or Syt3-GluA2 complex disruption improves neurological function and cognition.
• Syt3 knockout mice exhibit resistance to cerebral ischemia with maintained GluA2 surface expression and reduced CP-AMPARs.

Conclusions:

• Syt3-GluA2 interactions regulate CP-AMPAR formation, contributing to neurological deficits after ischemic insults.
• Targeting Syt3-GluA2 interactions presents a potential therapeutic strategy for treating ischemic brain injury.