Article

In Vitro Analysis of Huntingtin-Mediated Transcriptional Repression Reveals Multiple Transcription Factor Targets

Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, 401 Barker Hall, Berkeley, CA 94720, USA.
Cell (Impact Factor: 33.12). 01/2006; 123(7):1241-53. DOI: 10.1016/j.cell.2005.10.030
Source: PubMed

ABSTRACT Transcriptional dysregulation has emerged as a potentially important pathogenic mechanism in Huntington's disease, a neurodegenerative disorder associated with polyglutamine expansion in the huntingtin (htt) protein. Here, we report the development of a biochemically defined in vitro transcription assay that is responsive to mutant htt. We demonstrate that both gene-specific activator protein Sp1 and selective components of the core transcription apparatus, including TFIID and TFIIF, are direct targets inhibited by mutant htt in a polyglutamine-dependent manner. The RAP30 subunit of TFIIF specifically interacts with mutant htt both in vitro and in vivo to interfere with formation of the RAP30-RAP74 native complex. Importantly, overexpression of RAP30 in cultured primary striatal cells protects neurons from mutant htt-induced cellular toxicity and alleviates the transcriptional inhibition of the dopamine D2 receptor gene by mutant htt. Our results suggest a mutant htt-directed repression mechanism involving multiple specific components of the basal transcription apparatus.

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    • ") (Petrasch-Parwez et al., 2007) (Panov et al., 2002, 2005b) (Gizatullina et al., 2006) (Gellerich et al., 2008) (Lim et al., 2008; Milakovic and Johnson, 2005; Milakovic et al., 2006) (Lim et al., 2008; Oliveira et al., 2006, 2007) (Ruan et al., 2004) (Chang et al., 2006; Orr et al., 2008; Reddy et al., 2009; Trushina et al., 2004) (Johri et al., 2011; Shirendeb et al., 2012; Song et al., 2011b) (Wang et al., 2009) (Shirendeb et al., 2011b) (Chen-Plotkin et al., 2006; Dunah et al., 2002; Nucifora et al., 2001; Steffan et al., 2000; Sugars and Rubinsztein, 2003; Sugars et al., 2004; Zhai et al., 2005) (Chaturvedi et al., 2009b, 2010; Cui et al., 2006; McGill and Beal, 2006; Weydt et al., 2006) (Chaturvedi et al., 2012b) PINK1 PD 1. PINK1 knock-down causes decreased mitochondrial respiration and ATP synthesis, and increased α-synuclein aggregation in PD models 2. PINK1 mutants have defective ability to regulate opening of the mitochondrial permeability transition pore, MMP and cytochrome c release 3. PINK1 is rapidly degraded in healthy mitochondria but accumulates on the MMP deficient mitochondria, it recruits Parkin, to ubiquitnylate the damaged mitochondria for degradation through mitophagy 4. Parkin with PINK1, modulates mitochondrial trafficking, and mutations in either Parkin or PINK1 may alter mitochondrial turnover and causes accumulation of defective mitochondria 5. PINK1 induces mitochondrial dysfunction by disturbing Ca 2+ homeostasis in neuronal cells 6. PINK1 localizes to the brain mitochondrial membranes and protects cells against stress and mitochondrial toxin MPTP 7. PINK1 knockout mice have decreased mitochondrial respiration activity, increased mitochondrial dysfunction, enhanced susceptibility to oxidative stress and PD phenotypes 8. PINK1 phosphorylates Miro, which leads to proteasomal mediated degradation of Miro in a Parkin-dependent manner. This prevents mitochondrial movement and quarantines damaged mitochondria before clearance by mitophagy. "
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    • ") (Petrasch-Parwez et al., 2007) (Panov et al., 2002, 2005b) (Gizatullina et al., 2006) (Gellerich et al., 2008) (Lim et al., 2008; Milakovic and Johnson, 2005; Milakovic et al., 2006) (Lim et al., 2008; Oliveira et al., 2006, 2007) (Ruan et al., 2004) (Chang et al., 2006; Orr et al., 2008; Reddy et al., 2009; Trushina et al., 2004) (Johri et al., 2011; Shirendeb et al., 2012; Song et al., 2011b) (Wang et al., 2009) (Shirendeb et al., 2011b) (Chen-Plotkin et al., 2006; Dunah et al., 2002; Nucifora et al., 2001; Steffan et al., 2000; Sugars and Rubinsztein, 2003; Sugars et al., 2004; Zhai et al., 2005) (Chaturvedi et al., 2009b, 2010; Cui et al., 2006; McGill and Beal, 2006; Weydt et al., 2006) (Chaturvedi et al., 2012b) PINK1 PD 1. PINK1 knock-down causes decreased mitochondrial respiration and ATP synthesis, and increased α-synuclein aggregation in PD models 2. PINK1 mutants have defective ability to regulate opening of the mitochondrial permeability transition pore, MMP and cytochrome c release 3. PINK1 is rapidly degraded in healthy mitochondria but accumulates on the MMP deficient mitochondria, it recruits Parkin, to ubiquitnylate the damaged mitochondria for degradation through mitophagy 4. Parkin with PINK1, modulates mitochondrial trafficking, and mutations in either Parkin or PINK1 may alter mitochondrial turnover and causes accumulation of defective mitochondria 5. PINK1 induces mitochondrial dysfunction by disturbing Ca 2+ homeostasis in neuronal cells 6. PINK1 localizes to the brain mitochondrial membranes and protects cells against stress and mitochondrial toxin MPTP 7. PINK1 knockout mice have decreased mitochondrial respiration activity, increased mitochondrial dysfunction, enhanced susceptibility to oxidative stress and PD phenotypes 8. PINK1 phosphorylates Miro, which leads to proteasomal mediated degradation of Miro in a Parkin-dependent manner. This prevents mitochondrial movement and quarantines damaged mitochondria before clearance by mitophagy. "
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