title: A Septin-Dependent Diffusion Barrier at Dendritic Spine Necks.
abstract: Excitatory glutamatergic synapses at dendritic spines exchange and modulate their receptor content via lateral membrane diffusion. Several studies have shown that the thin spine neck impedes the access of membrane and solute molecules to the spine head. However, it is unclear whether the spine neck geometry alone restricts access to dendritic spines or if a physical barrier to the diffusion of molecules exists. Here, we investigated whether a complex of septin cytoskeletal GTPases localized at the base of the spine neck regulates diffusion across the spine neck. We found that, during development, a marker of the septin complex, Septin7 (Sept7), becomes localized to the spine neck where it forms a stable structure underneath the plasma membrane. We show that diffusion of receptors and bulk membrane, but not cytoplasmic proteins, is slower in spines bearing Sept7 at their neck. Finally, when Sept7 expression was suppressed by RNA interference, membrane molecules explored larger membrane areas. Our findings indicate that Sept7 regulates membrane protein access to spines.
authors.affiliation: Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France.
authors.forename: Helge
authors.initials: H
authors.lastname: Ewers
authors.affiliation: The Picower Institute for Learning and Memory, Departments of Brain and Cognitive Sciences and Biology, Massachusetts Institute of Technology, Cambridge, MA 02446, United States of America.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Tada
authors.affiliation: Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France.
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Petersen
authors.affiliation: Department of Anatomy and Histology, Faculty of Veterinary Science, Szent István University, 1078 Budapest, Hungary.
authors.forename: Bence
authors.initials: B
authors.lastname: Racz
authors.affiliation: The Picower Institute for Learning and Memory, Departments of Brain and Cognitive Sciences and Biology, Massachusetts Institute of Technology, Cambridge, MA 02446, United States of America.
authors.forename: Morgan
authors.initials: M
authors.lastname: Sheng
authors.affiliation: Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Choquet
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D049229:Dendritic Spines / Q000378:metabolism*; D004058:Diffusion; D005455:Fluorescent Antibody Technique; D020558:GTP Phosphohydrolases / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D009474:Neurons / Q000378:metabolism; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D058112:Septins / Q000235:genetics / Q000378:metabolism*
chemical_list: D020558:GTP Phosphohydrolases; C512894:Septin7 protein, rat; D058112:Septins