QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Vol. 21, Issue 1, 165-176, January 1, 2010

This Article Full Text Full Text (PDF) Supplemental Materials All Versions of this Article: E09-07-0596v1 21/1/165    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Korobova, F. Articles by Svitkina, T. Search for Related Content PubMed PubMed Citation Articles by Korobova, F. Articles by Svitkina, T.

Molecular Architecture of Synaptic Actin Cytoskeleton in Hippocampal Neurons Reveals a Mechanism of Dendritic Spine Morphogenesis

Department of Biology, The University of Pennsylvania, Philadelphia, PA 19104

Submitted July 22, 2009; Revised September 28, 2009; Accepted October 23, 2009
Monitoring Editor: Paul Forscher

Excitatory synapses in the brain play key roles in learning and memory. The formation and functions of postsynaptic mushroom-shaped structures, dendritic spines, and possibly of presynaptic terminals, rely on actin cytoskeleton remodeling. However, the cytoskeletal architecture of synapses remains unknown hindering the understanding of synapse morphogenesis. Using platinum replica electron microscopy, we characterized the cytoskeletal organization and molecular composition of dendritic spines, their precursors, dendritic filopodia, and presynaptic boutons. A branched actin filament network containing Arp2/3 complex and capping protein was a dominant feature of spine heads and presynaptic boutons. Surprisingly, the spine necks and bases, as well as dendritic filopodia, also contained a network, rather than a bundle, of branched and linear actin filaments that was immunopositive for Arp2/3 complex, capping protein, and myosin II, but not fascin. Thus, a tight actin filament bundle is not necessary for structural support of elongated filopodia-like protrusions. Dynamically, dendritic filopodia emerged from densities in the dendritic shaft, which by electron microscopy contained branched actin network associated with dendritic microtubules. We propose that dendritic spine morphogenesis begins from an actin patch elongating into a dendritic filopodium, which tip subsequently expands via Arp2/3 complex-dependent nucleation and which length is modulated by myosin II-dependent contractility.

Address correspondence to: Tatyana M. Svitkina (svitkina{at}sas.upenn.edu).

Abbreviations used: DIV, days in vitro; EM, electron microscopy; PSD, postsynaptic density.

This article has been cited by other articles:

				P. Hotulainen and C. C. Hoogenraad Actin in dendritic spines: connecting dynamics to function J. Cell Biol., May 17, 2010; 189(4): 619 - 629. [Abstract] [Full Text] [PDF]