Mizui Toshiyuki, Takahashi Hideto, Sekino Yuko, Shirao Tomoaki
Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Japan.
Mol Cell Neurosci. 2005 Dec;30(4):630-8.
Drebrin A is a neuron-specific F-actin binding protein, and plays a pivotal role in the spine formation. In this study, we expressed drebrin A tagged with green fluorescent protein (GFP-DA) in hippocampal neurons at 7-9 days in vitro when presynaptic terminals are not fully maturated. GFP-DA was accumulated in dendritic protrusions and formed large abnormal structures. Since these structures were similar to filopodia in terms of lack of MAP2 immunostaining, we named them "megapodia" meaning large dendritic filopodia. F-actin and PSD-95 were also accumulated in megapodia, and their amounts were significantly correlated with that of GFP-DA. However, the expression of GFP-DA did not result in the promotion of the morphological change from filopodia into spines. These results demonstrate that drebrin A accumulates spine-resident proteins via protein-protein interaction in filopodia, and suggest that the spine formation requires the concurrence of the increase of drebrin-A expression and the functional presynaptic contact.
Drebrin A是一种神经元特异性F-肌动蛋白结合蛋白，在棘突形成中起关键作用。在本研究中，我们在体外培养7-9天的海马神经元中表达了带有绿色荧光蛋白的Drebrin A（GFP-DA），此时突触前终末尚未完全成熟。GFP-DA在树突突起中积累并形成大的异常结构。由于这些结构在缺乏MAP2免疫染色方面与丝状伪足相似，我们将它们命名为“巨足”，意思是大的树突丝状伪足。F-肌动蛋白和PSD-95也在巨足中积累，它们的量与GFP-DA的量显著相关。然而，GFP-DA的表达并未导致丝状伪足向棘突的形态变化的促进。这些结果表明，Drebrin A通过丝状伪足中的蛋白质-蛋白质相互作用积累棘突驻留蛋白，并表明棘突形成需要Drebrin-A表达增加和功能性突触前接触的同时发生。
