Septin-3 and Septin-5 are components of the septin cytoskeleton highly expressed in the nervous system, yet the extent of their shared and distinct roles is not fully understood. We recently demonstrated that Septin-3 regulates late-phase long-term potentiation (L-LTP)-dependent invasion of smooth endoplasmic reticulum (sER) into dentate gyrus (DG) spines. Septin3−/− mice exhibit normal synaptic ultrastructure in the hippocampal DG, CA3, and CA1, yet the fraction of sER-containing spines is reduced; behaviorally, they show selective deficits in 1-day object recognition and 1-day contextual fear memory, whereas cued fear conditioning and contextual memory tested at 1 month are intact. Here, using adult male Septin5−/− mice, we tested whether morphological and behavioral phenotypes identified in Septin3−/− mice are shared or subunit-specific. Electron microscopy showed no detectable differences in synapse density, spine volume, and postsynaptic density (PSD) area in the hippocampal DG, CA3, and CA1, with an unchanged fraction of sER-containing spines relative to wild-type littermates. Behaviorally, Septin5−/− mice were impaired in recent (1 day) and remote (1 month) contextual fear memory, but were normal in 1-day novel object recognition memory and in recent and remote cued fear memory. The shared and distinct structural and behavioral phenotypes observed in Septin5−/− and Septin3−/− mice suggest either sER-independent common mechanisms or subunit-specific ones for recent contextual fear memory deficit, and indicate a Septin-5-dependent contribution to remote contextual fear memory.
Septin5 deficiency impairs both recent and remote contextual fear memory
N. Ageta-Ishihara,Naoto Fukumasu,Kodai Sakakibara,Kazuki Fujii,Yumie Koshidaka,Saori Katsuragawa,Kenji Tanigaki,T. Hiramoto,G. Kang,N. Hiroi,Yugo Fukazawa,Tsuyoshi Miyakawa,Keizo Takao,Makoto Kinoshita
Published 2025 in Molecular Brain
ABSTRACT
PUBLICATION RECORD
- Publication year
2025
- Venue
Molecular Brain
- Publication date
2025-11-13
- Fields of study
Biology, Medicine
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
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