Download MendeleyIQSEC2/BRAG1 may modulate postsynaptic density assembly through Ca2+-induced phase separation.
Bai, G., Huang, R., Nan, X., Zhuang, M., Wu, M., Lian, Y., Cai, Q., Tian, H., Lu, Y., Li, H., Zhang, M.(2025) J Cell Biol 224
- PubMed: 41123449
- DOI: https://doi.org/10.1083/jcb.202503076
- Primary Citation of Related Structures:
9M46 - PubMed Abstract:
IQSEC2, a high-confidence neurodevelopmental disorder risk gene product, is essential for neuronal development and synaptic plasticity. Previous studies established that IQSEC2 dynamically regulates synaptic signaling via Ca2+-dependent release of autoinhibition. In this study, using in vivo mouse models and in vitro biochemistry approaches, we discover that IQSEC2 orchestrates postsynaptic density assembly and dynamics via Ca2+-triggered phase separation. Mechanistically, Ca2+-induced conformational opening leads to phase separation-mediated condensation of IQSEC2 at synapses, a process that requires the N-terminal multimerization domain and intrinsically disordered regions of IQSEC2. We identified a single-point mutation, F367A, in IQSEC2, which exhibits constitutive activity by structurally mimicking the Ca2+-activated state of the WT protein. Mice carrying the Iqsec2_F367A mutation have elevated basal synaptic transmission and impaired activity-dependent plasticity assayed in hippocampal neurons and spatial learning deficits. Thus, IQSEC2 can bidirectionally modulate synaptic strengths via Ca2+-dependent phase separation, and dysregulation of phase separation may be a contributing factor in IQSEC2-related neurodevelopmental disorders.
- School of Life Sciences, Southern University of Science and Technology , Shenzhen, China.
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