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Updated: Jul 9, 2025

A High-content Assay for Monitoring AMPA Receptor Trafficking
Published on: January 28, 2019
C4 induces pathological synaptic loss by impairing AMPAR trafficking.
Rhushikesh A Phadke1, Ezra Kruzich2, Luke A Fournier2
1Molecular Biology, Cell Biology & Biochemistry Program, Boston University, Boston, MA, USA.
Overexpression of the schizophrenia-associated gene C4 causes synaptic loss independently of the complement receptor 3 pathway. This occurs via intracellular GluR1 degradation, a process that can be reversed by increasing SNX27 levels.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Complement pathway activation normally leads to microglia-dependent synaptic elimination via complement receptor 3 (CR3).
- Schizophrenia is associated with genetic factors, including complement component 4 (C4).
Approach:
- Investigated the mechanism of C4-mediated synaptic changes.
- Utilized overexpression of C4 (C4-OE) in a model system.
- Examined the role of CR3, endosomal trafficking protein SNX27, and GluR1 degradation.
Key Points:
- C4-OE-induced decreased connectivity is independent of CR3.
- C4-OE triggers pathological synaptic loss through intracellular GluR1 degradation.
- The endosomal trafficking protein SNX27 is involved in this mechanism.
Conclusions:
- Excessive complement activity, specifically C4-OE, links to intracellular endolysosomal pathways affecting synapses.
- SNX27 levels can rescue C4-OE-associated connectivity deficits.
- This identifies a novel intracellular mechanism for synaptic loss relevant to C4 function and potentially schizophrenia.
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