title: Spatially restricted actin-regulatory signaling contributes to synapse morphology.
abstract: The actin cytoskeleton in dendritic spines is organized into microdomains, but how signaling molecules that regulate actin are spatially governed is incompletely understood. Here we examine how the localization of the RacGEF kalirin-7, a well-characterized regulator of actin in spines, varies as a function of post-synaptic density area and spine volume. Using serial section electron microscopy, we find that extrasynaptic, but not synaptic, expression of kalirin-7 varies directly with synapse size and spine volume. Moreover, we find that overall expression levels of kalirin-7 differ in spines bearing perforated and non-perforated synapses, due primarily to extrasynaptic pools of kalirin-7 expression in the former. Overall, our findings indicate that kalirin-7 is differentially compartmentalized in spines as a function of both synapse morphology and spine size.
authors.affiliation: Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Nicholson
authors.forename: Michael E
authors.initials: ME
authors.lastname: Cahill
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Tulisiak
authors.forename: Yuri
authors.initials: Y
authors.lastname: Geinisman
authors.forename: Peter
authors.initials: P
authors.lastname: Penzes
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure*; D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism / Q000648:ultrastructure; D049229:Dendritic Spines / Q000378:metabolism / Q000648:ultrastructure; D020662:Guanine Nucleotide Exchange Factors / Q000096:biosynthesis*; D007125:Immunogenetics; D007150:Immunohistochemistry; D046529:Microscopy, Electron, Transmission; D051381:Rats; D015398:Signal Transduction / Q000502:physiology; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure*
chemical_list: D020662:Guanine Nucleotide Exchange Factors; C102365:Kalrn protein, rat