title: Histone deacetylase mediates the decrease in drebrin cluster density induced by amyloid beta oligomers.
abstract: Dendritic spine defects are found in a number of cognitive disorders, including Alzheimer's disease (AD). Amyloid beta (Aβ) toxicity is mediated not only by the fibrillar form of the protein, but also by the soluble oligomers (Aβ-derived diffusible ligands, ADDLs). Drebrin is an actin-binding protein that is located at mature dendritic spines. Because drebrin expression is decreased in AD brains and in cultured neurons exposed to Aβ, it is thought that drebrin is closely associated with cognitive functions. Recent studies show that histone deacetylase (HDAC) activity is elevated in the AD mouse model, and that memory impairments in these animals can be ameliorated by HDAC inhibitors. In addition, spine loss and memory impairment in HDAC2 over-expressing mice are ameliorated by chronic HDAC inhibitor treatment. Therefore, we hypothesized that the regulation of histone acetylation/deacetylation is critical to synaptic functioning. In this study, we examined the relationship between HDAC activity and synaptic defects induced by ADDLs using an HDAC inhibitor, suberoylanilide hydroxamic acid (SAHA). We show that ADDLs reduce the cluster density of drebrin along dendrites without reducing drebrin expression. SAHA markedly increased the acetylation of histone proteins, and it simultaneously attenuated the ADDL-induced decrease in drebrin cluster density. In comparison, SAHA treatment did not affect the density of drebrin clusters or dendritic protrusions in control neurons. Therefore, SAHA likely inhibits ADDL-induced drebrin loss from dendritic spines by stabilizing drebrin in these structures, rather than by increasing drebrin clusters or dendritic protrusions. Taken together, our findings suggest that HDAC is involved in ADDL-induced synaptic defects, and that the regulation of histone acetylation plays an important role in modulating actin cytoskeletal dynamics in dendritic spines under cellular stress conditions, such as ADDL exposure.
authors: Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors: Yuta
authors: Y
authors: Ishizuka
authors: Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors: Hideo
authors: H
authors: Shimizu
authors: Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors: Eiko
authors: E
authors: Takagi
authors: Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors: Mai
authors: M
authors: Kato
authors: Division of Neuropsychiatry, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikougushi, Ube, Yamaguchi 755-8505, Japan.
authors: Hirotaka
authors: H
authors: Yamagata
authors: Department of Psychiatry and Neuroscience, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors: Masahiko
authors: M
authors: Mikuni
authors: Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan. Electronic address: tshirao@gunma-u.ac.jp.
authors: Tomoaki
authors: T
authors: Shirao
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006655:Histone Deacetylases / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009479:Neuropeptides / Q000378:metabolism*
chemical_list: D016229:Amyloid beta-Peptides; D009479:Neuropeptides; C053386:drebrins; D006655:Histone Deacetylases
keywords: Alzheimer’s disease; Aβ-derived diffusible ligands; Dendritic spine; Drebrin; Histone acetylation; Histone deacetylase