Human Molecular Genetics, 2000, Vol. 9, No. 14 2175-2182
© 2000 Oxford University Press
Huntingtin’s WW domain partners in Huntington’s disease post-mortem brain fulfill genetic criteria for direct involvement in Huntington’s disease pathogenesis
Molecular Neurogenetics Unit and 1Laboratory for Molecular Neuropathology, Massachusetts General Hospital, Building 149, 13th Street, Charlestown, MA 02129, USA, 2Department of Genetics, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA 02115, USA and 3Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
Received 12 May 2000; Revised and Accepted 10 July 2000.
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
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An elongated glutamine tract in mutant huntingtin initiates Huntington’s disease (HD) pathogenesis via a novel structural property that displays neuronal selectivity, glutamine progressivity and dominance over the normal protein based on genetic criteria. As this mechanism is likely to involve a deleterious protein interaction, we have assessed the major class of huntingtin interactors comprising three WW domain proteins. These are revealed to be related spliceosome proteins (HYPA/FBP-11 and HYPC) and a transcription factor (HYPB) that implicate huntingtin in mRNA biogenesis. In HD post-mortem brain, specific antibody reagents detect each partner in HD target neurons, in association with disease-related N-terminal morphologic deposits but not with filter trapped insoluble-aggregate. Glutathione S-transferase partner ‘pull-down’ assays reveal soluble, aberrantly migrating, forms of full-length mutant huntingtin specific to HD target tissue. Importantly, these novel mutant species exhibit exaggerated WW domain binding that abrogates partner association with other huntingtin isoforms. Thus, each WW domain partner’s association with huntingtin fulfills HD genetic criteria, supporting a direct role in pathogenesis. Our findings indicate that modification of mutant huntingtin in target neurons may promote an abnormal interaction with one, or all, of huntingtin’s WW domain partners, perhaps altering ribonucleoprotein function with toxic consequences.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
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Huntington’s disease (HD), with its hallmark choreiform movements and graded loss of striatal neurons (1), is a dominantly inherited disorder caused by expansion of a CAG repeat in one copy of a novel 4p16.3 gene (HD) (2). The HD mutation elongates an N-terminal glutamine segment in huntingtin, conferring an abnormal structural attribute, that may act when embedded in the full-length >350 kDa protein or after cleavage in an N-terminal product (3). In either case, the evidence favors an abnormal aggregation-property (4) that seems likely to promote an aberrant interaction with a protein partner in target neurons (5).
The numerous reported N-terminal binding proteins suggest multiple pathways to be explored, including vesicle transport, cytoskeletal function, transcription and metabolism (6–12). In yeast two-hybrid studies, we identified portions of three proteins with related WW motifs that comprise the human homolog of the essential pre-mRNA splicing factor PrP40 (HYPA/FBP-11) (11), a putative spliceosome protein (HYPC) and a novel gene segment (HYPB). Each of these WW domain yeast partners exhibits enhanced binding to mutant protein in HD lymphoblast extracts, implying an interaction involving pre-mRNA splicing complexes that may be important to HD pathogenesis (11).
Genotype–phenotype studies in HD patients provide criteria for assessing any given partner interaction as a candidate for triggering pathogenesis. These reveal that the underlying HD pathogenic mechanism is selective for neurons in striatum and cortex, progressive with polyglutamine size, above a threshold of 
39 residues, and dominant over the wild-type protein (13). Furthermore, association with pathogenic correlates detected in HD post-mortem brain, including morphologic nuclear inclusions and neuropil deposits (14–16) and ‘trappable’ N-terminal amyloid (17) may reveal remnants of an interaction with mutant protein in target neurons.
Consequently, in this study we have investigated the molecular identity of the WW domain proteins and, in each case, have assessed the candidacy of the partner interaction in HD post-mortem brain to determine whether it conforms to genetic criteria for the pathogenic mechanism. Our findings support a role for huntingtin in mRNA biogenesis and suggest that initiation of the disease process may entail exaggerated binding of WW domain partners to modified isoforms of the mutant protein in HD target neurons.
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RESULTS |
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TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
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The WW domain partners implicate huntingtin in mRNA biogenesis
The related tandem WW domains in the yeast two-hybrid segments implied that HYPC, like HYPA/FBP-11, is a spliceosome protein (11). This prediction is confirmed by DNA sequence analysis of versions of the murine homologs, FBP-11 and HYPCL, which encode open reading frames (ORFs) of 953 and 872 amino acids, respectively. These proteins exhibit
58% overall identity and, as depicted in Figure 1, share domains found in pre-mRNA splicing factors: tandem WW motifs (18), an N-terminal PGM domain (proline-, glycine- and methionine-rich region) (19) and three FF domains (for spaced phenylalanine residues) (20). Notably, for each partner the database contains multiple spliced isoforms and homologs in lower organisms (11). The human loci, HYPA and HYPC, were mapped using a human–rodent somatic cell hybrid panel to chromosomes 2 and 12, respectively (data not shown).
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The HYPB yeast two-hybrid segment, with a single mildly related WW domain, is encoded as part of a widely expressed
9 kb mRNA (11). We identified this partner by assigning the locus to human chromosome 3 (data not shown), permitting exon prediction and expressed sequence tag (EST) database searches with HYPB genomic DNA sequence. Multiple versions of HYPB, consistent with alternate splicing, are found in EST databases (11), indicating isoforms of this partner. Database searches reveal that the HYPB WW domain segment forms an alternate C-terminus of HSPC069, the human homolog of the predicted Drosophila SET domain transcription factor CG1716 (GenBank accession no. AAF48272). Thus, huntingtin’s WW domain partners, essential pre-mRNA splicing proteins (HYPA/FBP-11, HYPC) and a transcription factor (HYPB), implicate huntingtin in mRNA biogenesis.
Specific antibody reagents detect WW domain partners in brain
To study the endogenous WW domain partners in HD post-mortem brain we used the glutathione S-transferase–HYP (GST–HYP) fusion proteins (Fig. 1) to generate polyclonal HYPA/FBP-11, HYPC and HYPB antibody reagents, named AF-1, CF-1 and BF-1, respectively. Immunoblot analyses, shown in Figure 2, reveal that each affinity-purified reagent specifically detects the cognate HYP-product cleaved from the GST, although in extracts of mouse and human brain and lymphoblastoid cells only endogenous HYPA/FBP-11 and HYPB are detected in this format. AF-1, and an independent FBP-11 reagent, 
11A, both reveal prominent (140 and 130 kDa) bands in most tissues. These products migrate more slowly than predicted by our full-length cDNA, indicating alternate isoforms of this partner that are consistent with alternately spliced mRNAs in EST databases (11).
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HYPB is detected by BF-1 reagents, but not pre-immune sera, as bands of
420 and 380 kDa in human cerebral cortex, 420, 285 and 200 kDa in lymphoblastoid cell extracts, and an 490 kDa band in whole mouse brain. Thus, as reflected by the host of alternate-splice versions found in databases (11), HYPB is an abundant protein with tissue-specific isoforms that share the segment bearing the specific BF-1 epitopes. In contrast, endogenous HYPC is not observed when immunoblots are probed with CF-1 antibodies (data not shown), although these reagents easily detect fusion protein. Therefore, consistent with lower mRNA levels (11), HYPC is less abundant than the related spliceosome partner HYPA/FBP-11.
Expression in HD target neurons
The HD mutation leads to the loss of medium spiny cells in the striatum, comprising 85% of all neurons in this region, and affects large pyramidal neurons in the cerebral cortex (1). Therefore, to test whether the WW domain partners are expressed in HD target cells we compared the immunostaining pattern of post-mortem tissue from control and HD cases neuropathologically evaluated as Vonsattel grade 3 denoting a loss of >80% of medium spiny neurons (1). In control tissue, the HYPA/FBP-11 reagents, AF1 and 11A, both detect nuclear speckles in abundant striatal neurons, indicating reactivity in medium spiny cells, and in large cortical pyramidal neurons which also exhibit a punctate cytoplasmic signal in the long processes (Fig. 3). In HD striatum, this staining pattern is ‘lost’. Few reactive striatal nuclei are evident, although numerous neuropil dots are detected, and remaining cortical pyramidal cells exhibit darkly stained nuclear speckles but are devoid of cytoplasmic staining. Notably, the HYPC-specific CF-1 reagents, but not the pre-immune sera, consistently detect weak CF-1-positive nuclear speckles in abundant neurons in striatum and cortex, although some cells exhibit exclusively cytoplasmic reactivity. This pattern is not observed in HD tissue, which instead features CF-1-positive neuropil dots.
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Unexpectedly, as HYPB is a transcription factor, BF-1 signal in control striatal neurons and select cortical pyramidal cells (layers III, V, VI) is primarily cytoplasmic with reactive dots in the white matter and internal capsule that indicate axonal staining. This pattern is dramatically changed in HD striatum. Darkly BF-1-positive neuropil clusters are found in a gradient that mirrors the loss of medium-sized spiny neurons that forms the HD neuropathologic rating system (1), and in the cortex prominent BF-1 reactive dots arranged in long tracts which suggest clumped reactivity in axons. Thus, the WW domain partners are expressed in striatal neurons lost in HD and epitopes in each case are detected in abnormal reactive dots and clumps in HD post-mortem sections.
Association with nuclear inclusions and neuropil deposits in HD striatum
To test whether the abnormally distributed partner reactivity is associated with ubiquitinated N-terminal deposits found in HD post-mortem brain (1), we examined HD and control striatum by confocal microscopy (Fig. 4). Unexpectedly, HD sections that are not immunostained exhibit a plethora of autofluorescent puncta, prominent in the neuropil. In contrast, autofluorescent clusters, detected at lower frequency in control sections, are confined to the neuronal cytoplasm. The striking puncta are not evident by light microscopy and do not appear to be lipofuscin. Notably, the puncta distribution in HD sections follows the graded cell loss in HD (data not shown), suggesting that these autofluorescent deposits are a novel pathologic correlate. The puncta are not detected by anti-ubiquitin monoclonal antibody (mAb), which reveals reactive dots within the autofluorescent pattern that are present in rare neuronal nuclei. Co-staining with BF-1, but not pre-immune sera, discloses small dots of reactivity in the neuropil and bright blobs of signal that do not overlap with ubiquitin stain but instead merge with autofluorescent clusters, indicating co-localization of HYPB with this disease correlate. Unfortunately, the autofluorescent pattern overshadows the weak specific CF-1 staining that is apparent by light microscopy, precluding an analysis of HYPC in this format. However, staining with AF-1 reveals that a subset of ubiquitin-reactive dots are also AF-1 positive, typically in nuclei that lack AF-1-reactive speckles, suggesting HYPA/FBP-11 recruitment into inclusions.
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The WW domain partners are not detected in SDS-insoluble HD brain aggregate
An intimate association of each WW domain partner with insoluble N-terminal aggregate was examined by probing filters of trapped SDS-resistant aggregate enriched from HD and control cortical fractions, with our specific antibody reagents. As shown in Figure 5, N-terminal reagents HP1 and AP229, specific for the proline-rich segment which is the site of WW domain interaction, detect the HD but not the control brain fraction. Probing with mAb 1F8, which recognizes epitopes formed by long soluble glutamine tracts, fails to reveal the insoluble polyglutamine conformation in the trapped HD insoluble-aggregate. Moreover, no partner antibody reagent detects either the control or the HD brain fractions, indicating that the WW domain partners are unlikely to be integral components of insoluble-aggregate. However, the accessibility of AP229 epitopes suggests that the detergent extraction may disrupt a non-covalent WW domain-mediated association with the proline-rich segment.
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Preferential binding to modified forms of mutant protein in HD brain extracts
A ‘pull-down’ assay, with the GST–HYP fusion proteins depicted in Figure 1, was used to monitor the capacity of each WW domain partner to bind soluble huntingtin in extracts of HD cerebral cortex versus non-target lymphoblast cells. As shown in Figure 6A, immunoblot analysis of complexes ‘pulled’ from lymphoblast extracts confirms the capture of mAb 2166-reactive full-length normal and mutant protein by each GST–WW domain partner, with a preference for the mutant band. The sensitive 1F8 mAb, as expected, detects only the mutant protein with its long glutamine tract.
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In contrast, HD cerebral cortex extracts yield a dramatically different staining pattern (Fig. 6B). mAb 2166-positive bands of normal and mutant protein, embedded in a reactive smear, are detected in GST–HYPB-bound complexes but are less evident in proteins bound by the other GST–partners. Rather, in these captured complexes nested mAb 2166 signals higher in the gel, evident on long exposure, are observed. Detection by reagent HP1 confirms that these novel bands are huntingtin (data not shown). Indeed, probing with the sensitive 1F8 mAb discloses a reactive fuzz crowning the 1F8-positive mutant band in the input extract and reveals that GST–partner fusion proteins in each case are enriched for portions of the smear. GST–HYPB weakly binds the full-length mutant band but favors the intermediate-mobility smear. GST–HYPC enriches for smear bands with the slowest and the fastest mobilities, whereas GST–HYPA captures the slowly migrating smear species. Capture by the latter partners does not enrich for the full-length 1F8-positive mutant band, revealing a strong preference for the novel bands.
Notably, the slowly migrating 1F8-positive smear is detected in the five HD cerebral cortex extracts tested, but not in extracts of HD cerebellum or in control cortex (data not shown). The identity of the novel mutant bands remains to be elucidated. However, low molecular weight 1F8-reactive huntingtin bands are not consistently detected, suggesting that the fuzz does not comprise multimers of truncated product but rather constitutes versions of full-length mutant protein with altered mobility. Variability in the glutamine tract seems unlikely, as we do not observe heterogeneity in HD CAG repeat size (data not shown). Thus, isoforms of the mutant protein with enhanced WW domain-binding properties may be generated in HD target tissue by post-translational modification.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
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The altered structural property conferred on mutant huntingtin by long glutamine tracts promotes aggregation, supporting the view that an abnormal protein interaction may initiate HD pathogenesis, although the toxic property may act when embedded in the entire
350 kDa protein or in a proposed truncated product (3). Our analyses of three WW domain binding partners support huntingtin’s role in mRNA biogenesis and demonstrate in HD post-mortem tissue the fulfillment of genetic criteria, suggesting that each candidate may participate in an aberrant event directly involved in producing HD pathogenesis. Two partners, HYPA/FBP-11 and HYPC, are pre-mRNA splicing factor family members that reside in nuclear speckles, sites of spliceosome activity, and in the cytoplasm where ribonucleoprotein complexes are partially assembled (21). The third WW domain protein, HYPB, is a predicted SET domain transcription factor, which in tissue sections is detected by specific BF-1 reagents in the neuronal cytoplasm. However, in cultured neuronal cells we find that nuclear BF-1 staining predominates (unpublished data), indicating that in vivo the HYPB transcription protein can assume distinct conformations that mask BF-1 epitopes. Thus, the WW domain partners and another interactor, N-CoR transcriptional repressor (12), comprise a functional category of essential pre-mRNA splicing and transcription factors. However, these partners do not appear to constitute a single pathway, arguing that huntingtin may participate in some general aspect of mRNA biogenesis that involves both cytoplasmic and nuclear ribonucleoprotein complexes. This functional role can be investigated in model systems to test whether huntingtin is, as suggested by its other numerous interactors, a multifunctional protein that may also participate in cytoskeletal function and vesicle trafficking.
Each WW domain partner is expressed in the striatal and cortical neurons that are the primary targets of mutant huntingtin. Moreover, fulfillment of genetic criteria directly implicates each partner in the pathogenic process. HYPA/FBP-11 and HYPB co-localize with N-terminal morphologic structures in HD post-mortem striatum, including nuclear inclusions and a novel gradient of autofluorescent clusters. However, no partner is integral to filter-trapped insoluble-N-terminal aggregate, although accessibility of the proline-rich binding site suggests possible non-covalent interactions. Partner reactivity in morphologic nuclear inclusions and neuropil clusters, therefore, is likely a vestige of an interaction with complexes involving soluble mutant protein in target neurons.
Indeed, each WW domain partner exhibits exaggerated binding to aberrantly migrating species of mutant protein with soluble 1F8-reactive glutamine tracts that are detected in HD target tissue. These novel species appear to be versions of the full-length mutant protein that possess a post-translational modification that critically promotes WW domain-mediated binding, perhaps via phosphorylation (22). Importantly, the aberrant interaction with modified mutant protein abrogates WW domain partner capture of other versions of huntingtin, including the normal protein. Thus, if abnormal WW domain binding is involved in HD, the process that determines the distribution of the novel mutant isoforms may explain the neuronal selectivity of the pathogenic process. Furthermore, in this scenario, the ultimately toxic consequences may derive from an increase, or dominant-negative loss, of an inherent huntingtin activity or, alternatively, an impact on the activities of the essential WW domain partner.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
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Molecular analyses and chromosomal mapping
Full-length cDNA versions of FBP-11 and HYPCL were isolated by screening Lambda Zap phage libraries with 32P-labeled FBP-11 (23) or HYPC (11) hybridization probes, respectively. The start codon of FBP-11 and the stop codon and poly(A) tail of HYPCL were obtained by 5' and 3' rapid amplification of cDNA ends (Stratagene, La Jolla, CA), respectively. Sequences are deposited in GenBank [accession nos AF135439 (FBP-11) and AF135440 (HYPCL)]. For HYPB, BLAST databases searches (NCBI) with HYPB sequence (GenBank accession no. AF049103) revealed identity to chromosome 3 bacterial artificial chromosome (BAC) sequence (GenBank accession nos AC020635 and AC018657). Searching with predicted exons (GENSCAN) then disclosed alternately spliced HYPB ESTs matching human HSPC069 (GenBank accession no. AF161554) upstream of the HYPB WW domain region in the BAC contig. Partner loci were assigned to human chromosomes by Southern blot analyses of restricted genomic DNA of a panel of rodent–human somatic cell hybrid lines (24) using specific 32P-labeled HYPA, HYPB and HYPC hybridization probes (11). HD CAG repeat size was determined by specific PCR assay (25).
Antibody reagents
Escherichia coli lysates of pGEX clones expressing GST-tagged segments of HYPA, HYPB and HYPC were prepared as previously reported (11). Specific polyclonal antibody reagents were generated for each partner by supplying GST fusion protein (Fig. 1) (11), excised from SDS–PAGE gel, to a commercial vendor (Covance, Denver, PA), producing three rabbit antisera for each fusion protein. Pre-immune sera were obtained before immunization. The specific reagents, named AF-1, BF-1 and CF-1, were affinity-purified by elution from nitrocellulose-immobilized thrombin-cleaved HYPA, HYPB or HYPC antigen lacking the GST moiety, respectively. Polyclonal reagent 11A was prepared by injecting rabbits with gel-purified FBP-11 fusion protein (WW domains and spacer region) (Pocono Rabbit Farm and Laboratory, Canadensis, PA), also used to generate affinity-purified reagent from immune sera. Other antibodies were as follows: huntingtin reagents mAb 2166 (residues 181–810) (Chemicon, Temecula, CA); HP1 (residues 80–113) (26); AP229 (residues 55–66); mAb 1F8 (27); and ubiquitin mAb 1510 (Chemicon).
Immunohistochemistry, light and confocal microscopy
Coronal microtome sections (7 µm) of paraffin-embedded frontal cortex (Brodmann area 9) and neostriatum (caudoputaminal junction) from four neuropathologically graded control and late-stage (grade 3) adult-onset HD cases were processed for specific immunostaining using standard methods (25). Some sections were incubated in buffer lacking either the primary or secondary antibody. Adsorption was by addition of antigen to the primary antibody incubation. Binding was visualized using biotinylated anti-rabbit IgG and avidin horseradish peroxidase complex (Vectastain Elite ABC kit; Vector Laboratories, Burlingame, CA) and detected with DAB (FAST DAB peroxidase tablet set; Sigma, St Louis, MO). For confocal microscopy (MRC 1024; Bio-Rad, Hercules, CA) binding was detected with Cy3-conjugated goat anti-rabbit and Cy2-conjugated goat anti-mouse (Jackson ImmunoResearch, West Grove, PA). Separate digitized images for each channel were merged with Adobe Photoshop.
Filter-trap assay for SDS-insoluble-aggregate
SDS-insoluble-enriched protein fractions were prepared, from frontal cortex of post-mortem HD (grade 3) and control brain, and immobilized on 0.22 µm pore size cellulose acetate membrane according to the published protocol (17).
Protein extracts, GST–HYP fusion protein ‘pull-down’ assay and immunoblotting
Lymphoblastoid cell extracts were prepared as described (11). Soluble extracts of dissected post-mortem frontal cortex and cerebellum, from five HD (grade 3) and two control cases, were generated by homogenization at 4°C in 0.15 M sucrose, 15 mM Tris–Cl pH 7.9, 60 mM KCl, 15 mM NaCl, 5 mM EDTA, 1 mM EGTA and Complete protease inhibitor (Boehringer Mannheim, Indianapolis, IN). Pull-down assay using sepharose 4B-immobilized GST–HYP fusion protein beads was as described (11). Protein determinations were by modified Bradford assay (Bio-Rad). Complexes were eluted from washed beads by boiling in SDS sample buffer. Extracts and captured complexes were loaded on 10% SDS–PAGE minigels and then blotted to nitrocellulose membrane. Immunoblots were probed with antibody reagents and detected by enhanced chemiluminescence as described (11).
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ACKNOWLEDGEMENTS |
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We thank Wendy Hobbs and Jayalakshmi Srinidhi for expert technical assistance. We thank Dr P. Leder for advice and helpful suggestions. This work has been supported by NINDS grants NS16367 (HD Center Without Walls) and NS32765 and by grants from the Huntington’s Disease Society of America (Coalition for the Cure) to M.E.M. and A.H.S. L.A.P. is the recipient of a John J. Wasmuth postdoctoral fellowship from the Hereditary Disease Foundation. M.T.B. is supported in part by Award 1440 of the Cancer Research Fund of the Damon Runyon–Walter Winchell Foundation. P.W.F. was a fellow of the Human Frontiers Program. Human post-mortem brain was provided by the Harvard Brain Tissue Resource Center, supported by PHS grant MH/NS 31862.
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FOOTNOTES |
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+ Present address: Cancer Center, Massachusetts General Hospital, Charlestown, MA 02129, USA
§ To whom correspondence should be addressed. Tel: +1 617 726 5089; Fax: +1 617 726 5735; Email: macdonam@helix.mgh.harvard.edu
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REFERENCES |
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TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
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B. Dehay and A. Bertolotti Critical Role of the Proline-rich Region in Huntingtin for Aggregation and Cytotoxicity in Yeast J. Biol. Chem., November 24, 2006; 281(47): 35608 - 35615. [Abstract] [Full Text] [PDF]
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X.-J. Sun, J. Wei, X.-Y. Wu, M. Hu, L. Wang, H.-H. Wang, Q.-H. Zhang, S.-J. Chen, Q.-H. Huang, and Z. Chen Identification and Characterization of a Novel Human Histone H3 Lysine 36-specific Methyltransferase J. Biol. Chem., October 21, 2005; 280(42): 35261 - 35271. [Abstract] [Full Text] [PDF]
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A. Khoshnan, J. Ko, E. E. Watkin, L. A. Paige, P. H. Reinhart, and P. H. Patterson Activation of the I{kappa}B Kinase Complex and Nuclear Factor-{kappa}B Contributes to Mutant Huntingtin Neurotoxicity J. Neurosci., September 15, 2004; 24(37): 7999 - 8008. [Abstract] [Full Text] [PDF]
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Z.-H. Qin, Y. Wang, E. Sapp, B. Cuiffo, E. Wanker, M. R. Hayden, K. B. Kegel, N. Aronin, and M. DiFiglia Huntingtin Bodies Sequester Vesicle-Associated Proteins by a Polyproline-Dependent Interaction J. Neurosci., January 7, 2004; 24(1): 269 - 281. [Abstract] [Full Text] [PDF]
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J. Xia, D. H. Lee, J. Taylor, M. Vandelft, and R. Truant Huntingtin contains a highly conserved nuclear export signal Hum. Mol. Genet., June 15, 2003; 12(12): 1393 - 1403. [Abstract] [Full Text] [PDF]
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S. Holbert, A. Dedeoglu, S. Humbert, F. Saudou, R. J. Ferrante, and C. Neri Cdc42-interacting protein 4 binds to huntingtin: Neuropathologic and biological evidence for a role in Huntington's disease PNAS, March 4, 2003; 100(5): 2712 - 2717. [Abstract] [Full Text] [PDF]
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A. Khoshnan, J. Ko, and P. H. Patterson Effects of intracellular expression of anti-huntingtin antibodies of various specificities on mutant huntingtin aggregation and toxicity PNAS, January 22, 2002; 99(2): 1002 - 1007. [Abstract] [Full Text] [PDF]
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S. Holbert, I. Denghien, T. Kiechle, A. Rosenblatt, C. Wellington, M. R. Hayden, R. L. Margolis, C. A. Ross, J. Dausset, R. J. Ferrante, et al. The Gln-Ala repeat transcriptional activator CA150 interacts with huntingtin: Neuropathologic and genetic evidence for a role in Huntington's disease pathogenesis PNAS, January 24, 2001; (2001) 41566798. [Abstract] [Full Text]
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P. Rizzu, M. Joosse, R. Ravid, A. Hoogeveen, W. Kamphorst, J. C. van Swieten, R. Willemsen, and P. Heutink Mutation-dependent aggregation of tau protein and its selective depletion from the soluble fraction in brain of P301L FTDP-17 patients Hum. Mol. Genet., December 1, 2000; 9(20): 3075 - 3082. [Abstract] [Full Text] [PDF]
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P. Hilditch-Maguire, F. Trettel, L. A. Passani, A. Auerbach, F. Persichetti, and M. E. MacDonald Huntingtin: an iron-regulated protein essential for normal nuclear and perinuclear organelles Hum. Mol. Genet., November 1, 2000; 9(19): 2789 - 2797. [Abstract] [Full Text] [PDF]
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F. Trettel, D. Rigamonti, P. Hilditch-Maguire, V. C. Wheeler, A. H. Sharp, F. Persichetti, E. Cattaneo, and M. E. MacDonald Dominant phenotypes produced by the HD mutation in STHdhQ111 striatal cells Hum. Mol. Genet., November 1, 2000; 9(19): 2799 - 2809. [Abstract] [Full Text] [PDF]
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A. Khoshnan, J. Ko, and P. H. Patterson Effects of intracellular expression of anti-huntingtin antibodies of various specificities on mutant huntingtin aggregation and toxicity PNAS, January 22, 2002; 99(2): 1002 - 1007. [Abstract] [Full Text] [PDF]
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S. Holbert, I. Denghien, T. Kiechle, A. Rosenblatt, C. Wellington, M. R. Hayden, R. L. Margolis, C. A. Ross, J. Dausset, R. J. Ferrante, et al. The Gln-Ala repeat transcriptional activator CA150 interacts with huntingtin: Neuropathologic and genetic evidence for a role in Huntington's disease pathogenesis PNAS, February 13, 2001; 98(4): 1811 - 1816. [Abstract] [Full Text] [PDF]
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