Role of neuropsin in formation and maturation of Schaffer-collateral L1cam-immunoreactive synaptic boutons.
We report that neuropsin is involved in the synaptogenesis/maturation of orphan and small synaptic boutons in the Schaffer-collateral pathway. Most non-synaptic orphan boutons and a number of immature small synaptic boutons expressed the cell adhesion molecule L1 in presynaptic Schaffer-collateral terminals, whereas mature large boutons on mushroom spines were devoid of L1. The number of L1-immunoreactive boutons was markedly higher in neuropsin-deficient mice than in wild-type mice, whereas there were far fewer mature large boutons. L1-immunoreactive boutons were hypertrophied in the mutant mice. When a recombinant active neuropsin was microinjected into the mutant hippocampus, the number of immunoreactive synaptic boutons reverted to wild-type levels after one day. These results strongly suggest that enzymatically active neuropsin allows a maturational change of L1-immunoreactive small boutons, both orphan and synaptic, and this step may be important in synaptic plasticity based on activity-dependent structural change.
Division of Structural Cell Biology, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0192, Japan.
Yukiko
Y
Nakamura
Hideki
H
Tamura
Kazuhiro
K
Horinouchi
Sadao
S
Shiosaka
D000818:Animals; D015153:Blotting, Western; D004594:Electrophysiology; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007610:Kallikreins; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D039842:Neural Cell Adhesion Molecule L1 / Q000378:metabolism* / Q000648:ultrastructure; D017729:Presynaptic Terminals / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D012333:RNA, Messenger / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism* / Q000648:ultrastructure; D013569:Synapses / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure
D039842:Neural Cell Adhesion Molecule L1; D012333:RNA, Messenger; D007610:Kallikreins; C114664:Prss19 protein, mouse; D012697:Serine Endopeptidases