Chazeau Anaël, Mehidi Amine, Nair Deepak, Gautier Jérémie J, Leduc Cécile, Chamma Ingrid, Kage Frieda, Kechkar Adel, Thoumine Olivier, Rottner Klemens, Choquet Daniel, Gautreau Alexis, Sibarita Jean-Baptiste, Giannone Grégory
Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France.
CNRS UPR3082, Laboratoire d'Enzymologie et Biochimie Structurales, Gif-sur-Yvette Cedex, France.
EMBO J. 2014 Dec 1;33(23):2745-64. doi: 10.15252/embj.201488837. Epub 2014 Oct 7.
Actin dynamics drive morphological remodeling of neuronal dendritic spines and changes in synaptic transmission. Yet, the spatiotemporal coordination of actin regulators in spines is unknown. Using single protein tracking and super-resolution imaging, we revealed the nanoscale organization and dynamics of branched F-actin regulators in spines. Branched F-actin nucleation occurs at the PSD vicinity, while elongation occurs at the tip of finger-like protrusions. This spatial segregation differs from lamellipodia where both branched F-actin nucleation and elongation occur at protrusion tips. The PSD is a persistent confinement zone for IRSp53 and the WAVE complex, an activator of the Arp2/3 complex. In contrast, filament elongators like VASP and formin-like protein-2 move outwards from the PSD with protrusion tips. Accordingly, Arp2/3 complexes associated with F-actin are immobile and surround the PSD. Arp2/3 and Rac1 GTPase converge to the PSD, respectively, by cytosolic and free-diffusion on the membrane. Enhanced Rac1 activation and Shank3 over-expression, both associated with spine enlargement, induce delocalization of the WAVE complex from the PSD. Thus, the specific localization of branched F-actin regulators in spines might be reorganized during spine morphological remodeling often associated with synaptic plasticity.
肌动蛋白动力学驱动神经元树突棘的形态重塑以及突触传递的变化。然而，棘突中肌动蛋白调节因子的时空协调尚不清楚。利用单蛋白追踪和超分辨率成像，我们揭示了棘突中分支丝状肌动蛋白（F-肌动蛋白）调节因子的纳米级组织和动力学。分支F-肌动蛋白成核发生在突触后密度（PSD）附近，而伸长发生在指状突起的尖端。这种空间分隔不同于片状伪足，在片状伪足中，分支F-肌动蛋白成核和伸长都发生在突起尖端。PSD是IRSp53和WAVE复合物（一种Arp2/3复合物激活剂）的持续限制区域。相比之下，像VASP和类formin蛋白-2这样的丝状肌动蛋白伸长因子随着突起尖端从PSD向外移动。因此，与F-肌动蛋白相关的Arp2/3复合物是固定的，并围绕着PSD。Arp2/3和Rac1 GTP酶分别通过胞质溶胶和膜上的自由扩散汇聚到PSD。增强的Rac1激活和Shank3过表达都与棘突增大有关，它们会诱导WAVE复合物从PSD发生离位。因此，在通常与突触可塑性相关的棘突形态重塑过程中，棘突中分支F-肌动蛋白调节因子的特定定位可能会被重新组织。
