HDAC4 interacts with mutant huntingtin <i>in vitro</i> and <i>in vivo</i> and colocalizes with cytoplasmic inclusions.

<p>(A) GST pull-down assays revealed that HDAC4 interacts with mutant (53Q) but not WT (20Q) exon 1 HTT. In contrast HDAC5 weakly interacts with both mutant and WT exon 1 HTT. The coomassie stained gel shows the exon 1 HTT GST fusion proteins that were used to pull-down ³⁵S-methioine labelled recombinant HDAC4 or HDAC5. (B) Western blot probed for HTT (MAB2166 or MW1) after immunoprecipitation with HDAC4 (DM-15) from brain tissue from 8-wk-old WT and <i>Hdh</i>Q150 heterozygous and homozygous mice (representative picture of three independent experiments). (C) Western blot probed for mutant HTT (MW1) after immunoprecipitation with HDAC4 (H-92) from brain tissue from 8-wk-old WT, <i>Hdh</i>Q20, and <i>Hdh</i>Q80 homozygous mice. (D) Western blot probed for mutant HTT (MAB2166 or MW1) after immunoprecipitation with HDAC5 (ab56929) from brain tissue from 8-wk-old WT and <i>Hdh</i>Q80 homozygous mice. (E) Representative immunofluorescence images of cortex from 14-wk-old R6/2 and 23-mo-old <i>Hdh</i>Q150 mice immunostained for mutant HTT (S830) and HDAC4 (CS2072) and counterstained with DAPI. A similar pattern of cytoplasmic co-localisation was also seen in the striatum and hippocampus. Scale bar, 15 µm. IP, immunoprecipitation; ID, immunodetection.