Septin 11 is present in GABAergic synapses and plays a functional role in the cytoarchitecture of neurons and GABAergic synaptic connectivity.
Mass spectrometry and immunoblot analysis of a rat brain fraction enriched in type-II postsynaptic densities and postsynaptic GABAergic markers showed enrichment in the protein septin 11. Septin 11 is expressed throughout the brain, being particularly high in the spiny branchlets of the Purkinje cells in the molecular layer of cerebellum and in the olfactory bulb. Immunofluorescence of cultured hippocampal neurons showed that 54 +/- 4% of the GABAergic synapses and 25 +/- 2% of the glutamatergic synapses had colocalizing septin 11 clusters. Similar colocalization numbers were found in the molecular layer of cerebellar sections. In cultured hippocampal neurons, septin 11 clusters were frequently present at the base of dendritic protrusions and at the bifurcation points of the dendritic branches. Electron microscopy immunocytochemistry of the rat brain cerebellum revealed the accumulation of septin 11 at the neck of dendritic spines, at the bifurcation of dendritic branches, and at some GABAergic synapses. Knocking down septin 11 in cultured hippocampal neurons with septin 11 small hairpin RNAs showed (i) reduced dendritic arborization; (ii) decreased density and increased length of dendritic protrusions; and (iii) decreased GABAergic synaptic contacts that these neurons receive. The results indicate that septin 11 plays important roles in the cytoarchitecture of neurons, including dendritic arborization and dendritic spines, and that septin 11 also plays a role in GABAergic synaptic connectivity.
Li
Xuejing
X
From the Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269.
Serwanski
David R
DR
From the Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269.
Miralles
Celia P
CP
From the Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269.
Nagata
Koh-Ichi
KI
Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, 713-8 Kamiya-Cho, Kasugai, Aichi 480-0392, Japan.
De Blas
Angel L
AL
From the Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269. Electronic address: angel.deblas@uconn.edu.
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D002478:Cells, Cultured; D002531:Cerebellum / Q000378:metabolism / Q000648:ultrastructure; D003001:Cloning, Molecular; D003712:Dendrites / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D058112:Septins; D013569:Synapses / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D005680:gamma-Aminobutyric Acid; C544350:Septin11 protein, rat; D020558:GTP Phosphohydrolases; D058112:Septins