1. Isoform-dependent Regulation of Drebrin Dynamics in Dendritic Spines
- Author
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Nobuhiko Kojima, Hiroyuki Yamazaki, Tomoaki Shirao, Kenji Hanamura, and Yousuke Kamata
- Subjects
0301 basic medicine ,Gene isoform ,Dendritic spine ,Dendritic Spines ,macromolecular substances ,Hippocampal formation ,Hippocampus ,Filamentous actin ,03 medical and health sciences ,0302 clinical medicine ,Animals ,Protein Isoforms ,Synapse formation ,Rats, Wistar ,Cells, Cultured ,Protein Stability ,Chemistry ,General Neuroscience ,Neuropeptides ,Fluorescence recovery after photobleaching ,Preferential binding ,Actins ,Cell biology ,030104 developmental biology ,030217 neurology & neurosurgery ,Latrunculin A - Abstract
Dendritic spines have stable filamentous actin (F-actin) and dynamic F-actin. The formation of stable F-actin plays a pivotal role in spine formation. Drebrin binds to and stabilizes F-actin in dendritic spines. Interestingly, the conversion of the drebrin E isoform to drebrin A occurs in parallel with synapse formation, suggesting that this conversion promotes synapse formation via F-actin accumulation. In this study, we measured the dynamics of GFP-tagged drebrin E (GFP-DE) and drebrin A (GFP-DA) in cultured hippocampal neurons by fluorescence recovery after photobleaching analysis. We found that GFP-DA has a larger stable fraction than GFP-DE. The stable drebrin fraction reflects its accumulation in dendritic spines, therefore the isoform conversion may increase the amount of stable F-actin in dendritic spines. The stable fraction was dependent on the drebrin A-specific sequence "Ins2", located in the middle of the drebrin protein. In addition, F-actin depolymerization with latrunculin A significantly reduced the stable GFP-DA fraction. These findings indicate that preferential binding of drebrin A to F-actin than drebrin E causes higher stable fraction of drebrin A in dendritic spines, although the F-actin-binding ability of purified drebrin E and drebrin A are comparable. Therefore, we suggest that a drebrin isoform conversion from drebrin E to drebrin A in dendritic spines results in the accumulation of drebrin-bound stable F-actin, which plays a pivotal role in synapse formation.
- Published
- 2018