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Human Molecular Genetics Pages 673-682  

Evidence for proteasome involvement in polyglutamine disease: localization to nuclear inclusions in SCA3/MJD and suppression of polyglutamine aggregation in vitro
Introduction
Results
   The proteasome is recruited into NI of SCA3/MJD brain
   In vitro modeling of proteasome recruitment into polyglutamine aggregates
   Full-length mutant ataxin-3 forms NI that recruit the proteasome and correspond to promyelocytic leukemia antigen (PML) oncogenic domains (PODs)
   Proteasome inhibition increases polyglutamine aggregation
Discussion
Materials And Methods
   Expression plasmids
   Cell culture and transfection
   Protease inhibitor treatment
   Immunocytochemistry
   Immunohistochemistry
   Quantitation of aggregates and cell viability
   Immunoblot and cell fractionation studies
Acknowledgements
Abbreviations
References

Evidence for proteasome involvement in polyglutamine disease: localization to nuclear inclusions in SCA3/MJD and suppression of polyglutamine aggregation in vitro

Evidence for proteasome involvement in polyglutamine disease: localization to nuclear inclusions in SCA3/MJD and suppression of polyglutamine aggregation in vitro

Yaohui Chai, Stacia L. Koppenhafer, Sarah J. Shoesmith, Matthew K. Perez1 and Henry L. Paulson*

Department of Neurology, University of Iowa College of Medicine, Iowa City, IA 52242, USA and 1Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104, USA

Received November 24, 1998 Revised and Accepted January 17, 1999

Spinocerebellar ataxia type 3, also known as Machado-Joseph disease (SCA3/MJD), is one of at least eight inherited neurodegenerative diseases caused by expansion of a polyglutamine tract in the disease protein. Here we present two lines of evidence implicating the ubiquitin-proteasome pathway in SCA3/MJD pathogenesis. First, studies of both human disease tissue and in vitro models showed redistribution of the 26S proteasome complex into polyglutamine aggregates. In neurons from SCA3/MJD brain, the proteasome localized to intranuclear inclusions containing the mutant protein, ataxin-3. In transfected cells, the proteasome redistributed into inclusions formed by three expanded polyglutamine proteins: a pathologic ataxin-3 fragment, full-length mutant ataxin-3 and an unrelated GFP-polyglutamine fusion protein. Inclusion formation by the full-length mutant ataxin-3 required nuclear localization of the protein and occurred within specific subnuclear structures recently implicated in the regulation of cell death, promyelocytic leukemia antigen oncogenic domains. In a second set of experiments, inhibitors of the proteasome caused a repeat length-dependent increase in aggregate formation, implying that the proteasome plays a direct role in suppressing polyglutamine aggregation in disease. These results support a central role for protein misfolding in the pathogenesis of SCA3/MJD and suggest that modulating proteasome activity is a potential approach to altering the progression of this and other polyglutamine diseases.

INTRODUCTION

Polyglutamine expansion is now recognized to be a major cause of inherited neurodegenerative disease (1). At least eight disorders are due to expansion of a CAG triplet repeat that encodes polyglutamine in the specific disease protein: Huntington’s disease, spinobulbar muscular atrophy, dentatorubral pallidoluysian atrophy and five dominantly inherited spinocerebellar ataxias (SCA), types 1, 2, 3, 6 and 7 (reviewed in refs 1-3). Although these diseases differ clinically and pathologically, a common pathogenic mechanism likely underlies them all (except possibly SCA6, which is due to a much smaller polyglutamine expansion in a calcium channel). Increasing evidence indicates that expanded polyglutamine confers a novel toxic property upon the otherwise unrelated polyglutamine disease proteins. Polyglutamine expansion leads to an altered, presumably misfolded, domain within the protein (4-6). One clear manifestation of this misfolding is the formation of intracellular aggregates by the disease protein, in particular intranuclear aggregates or nuclear inclusions (NI). NI have now been observed in at least six polyglutamine diseases and numerous transgenic animal models and thus represent a common hallmark of polyglutamine diseases (reviewed in refs 3,7,8; see also refs 9-11). NI are most frequently found in neurons from brain regions known to be susceptible to degeneration, suggesting that their formation may be important in disease pathogenesis.

The fact that NI are ubiquitinated supports the view that they contain misfolded and aggregated protein. The presence of ubiquitinated aggregates implies that alterations in the major intracellular system for degrading proteins, the ubiquitin-proteasome pathway, may contribute to the pathogenesis of polyglutamine diseases. The proteasome is a large multicatalytic protease complex that is critical for many cellular processes including cell cycle control, differentiation, antigen presentation and cell survival (12). It is responsible for the ubiquitin-dependent degradation of most cytosolic proteins, including the regulated destruction of short-lived cellular proteins and the elimination of misfolded or damaged proteins. Although proteasomes are abundant in the brain (13), their precise functions in neurons are still not fully understood. Recently, however, it has become clear that the control of protein degradation affects neuronal function under normal conditions and in disease states (14-16). The function of the proteasome in neurodegenerative diseases is particularly relevant since many neurodegenerative diseases are associated with protein misfolding and aggregation (17,18).

Studies of the polyglutamine disease SCA1 recently demonstrated redistribution of the proteasome into NI formed by the disease protein, ataxin-1 (19). To determine whether the proteasome is involved more generally in the polyglutamine diseases and to gain insight into its possible mode of action with respect to pathogenesis, we have examined the role of the ubiquitin-proteasome pathway in another polyglutamine disease, SCA3, also known as Machado-Joseph disease (SCA3/MJD). The most common dominantly inherited ataxia, SCA3/MJD is typically characterized by progressive ataxia with variable degrees of brainstem dysfunction, parkinsonism, dystonia and neuropathy (reviewed in ref. 20). Pathological findings in SCA3/MJD also vary, but commonly include degeneration within the globus pallidus, regions of the brainstem and spinal cord (21-23). SCA3/MJD is due to a polyglutamine expansion in the gene product of the MJD1 gene, called MJD1p or ataxin-3 (24). At 42 kDa, ataxin-3 is the smallest of the polyglutamine disease proteins. Its glutamine repeat lies near the C-terminus of the protein, where it is normally 14-40 repeats in length and is expanded in disease to between 55 and 80 repeats (reviewed in ref. 20). Ubiquitinated NI containing ataxin-3 have been observed in regions of SCA3/MJD brain susceptible to degeneration, including the pons and other brainstem structures (25,26).

Using cell-based models and human disease tissue, we demonstrate here that the ubiquitin-proteasome pathway is involved in SCA3/MJD. We show that the proteasome complex redistributes into polyglutamine aggregates formed by the disease protein ataxin-3, both in human disease tissue and in vitro. Moreover, we present findings that suggest proteasome function is closely linked to aggregate formation, as inhibitors of proteasome activity promote aggregation in transfected cells. Taken together with similar findings in SCA1 (19), our studies implicate the ubiquitin-proteasome pathway as a general rule in polyglutamine diseases and suggest possible avenues for future therapeutic intervention.

RESULTS

The proteasome is recruited into NI of SCA3/MJD brain

NI appear to be a constant pathologic finding in SCA3/MJD, as we have observed NI in all 13 SCA3/MJD cases we have examined (25; H. Paulson and S. Subramony, unpublished data) and others have also reported them using different antisera against the disease protein, ataxin-3 (26). To determine whether the proteasome co-localizes to NI in SCA3/MJD, we performed immunohistochemical staining on brainstem sections of an SCA3/MJD brain known to have abundant NI (25). As shown in Figure 1, NI immunostained positively for the two major macromolecular complexes comprising the 26S proteasome complex: the 20S core that forms the central proteolytic chamber and the 19S cap, also known as PA700, that is necessary for the ATP-dependent delivery of unfolded polypeptide to the 20S core (12). NI also immunostained for a third proteasome macromolecular complex, the 11S regulator, which is believed to play a role in antigen processing in certain cell types (12). For each of these three proteasome components, the frequency of immunopositive NI was lower than that seen with anti-ubiquitin staining of adjacent sections, which labels essentially all NI (25). This variable staining with anti-proteasome antibodies indicates that NI in SCA3/MJD are heterogeneous with respect to molecular composition, with the proteasome being redistributed into a subset of NI. Staining was negative for several other components of the ubiquitin-mediated degradation pathway, including the ubiquitin conjugating enzyme E2 and ubiquitin C-terminal hydrolase (data not shown).


Figure 1. The proteasome localizes to nuclear inclusions in SCA3/MJD. Pontine neurons in SCA3/MJD brain immunostained with antisera to ubiquitin (Ubi) or to components of the proteasome complex: the 20S proteasome core (20S), the 19S proteasome cap (TBP7) and the 11S proteasome regulator (PA28). In each case, spherical NI stain positively for the indicated antigen (TBP7 and PA28 are subunits of the 19S and 11S complexes, respectively). The inset (upper right) shows a higher power view of one of the NI-containing neurons positively stained for the 20S core (NI indicated by arrow, nucleolus indicated by arrowhead). Neurons in control brain did not show discrete immunostaining of subnuclear structures. Tissue sections were not counterstained.

In vitro modeling of proteasome recruitment into polyglutamine aggregates

To better define the molecular determinants of proteasome recruitment, we employed a cellular model of polyglutamine aggregation. Previously we showed that a truncated ataxin-3 fragment with 78 glutamine repeats (Q78) is a potent aggregant, forming intranuclear or perinuclear aggregates in every cell line we have tested (e.g. the cell lines HEK 293, HEK293T, Cos-7, HeLa, MN-1 and PC12, as well as cultured primary neurons; 25,27). From its N-terminus, Q78 consists of an epitope tag [either hemagglutinin (HA) or myc], the 13 amino acids upstream of the glutamine repeat, the expanded glutamine repeat and the subsequent 43 amino acids comprising the C-terminus of the protein as originally published (24). In HeLa cells, myc-Q78 forms intranuclear and perinuclear aggregates. As shown in Figure 2A, the 20S proteasome core was found to redistribute into polyglutamine aggregates formed in both subcellular locations. The 19S cap of the 26S proteasome complex also redistributed into polyglutamine aggregates, as shown by immunofluorescence studies with an antibody against a protein from the 19S cap, ubiquitin isopeptidase Uch37 (28). Similar results were obtained in Cos-7 and 293 cells (data not shown). In all three cell types, nearly all polyglutamine aggregates stained positively for the 20S proteasome core.


Figure 2. The proteasome redistributes into polyglutamine aggregates in transfected cells. (A) In HeLa cells expressing the mutant ataxin-3 fragment, myc-Q78, polyglutamine aggregates form either in the perinuclear region (top) or in the nucleus (bottom). Co-immunofluorescence staining demonstrates that the 20S proteasome core (red) redistributes into polyglutamine aggregates (green) in either cellular location, confirmed by coincident immunostaining in the merged images. (B) In primary cultured neurons transfected with GFP fused to a Q80 repeat, the proteasome (red) is recruited into many but not all aggregates (green). (Compare upper and lower panels, which show proteasome redistribution only in the upper panel.)

Aggregates formed by Q78 are highly insoluble, migrating as high molecular weight complexes in the stacking portion of SDS-polyacrylamide gels (25). Immunoblot analysis suggested that the proteasome complex is not trapped within these insoluble complexes since 20S core proteins did not co-migrate with polyglutamine aggregates in the stacking gel (data not shown). Thus, proteasomes that redistribute into inclusions are apparently not irreversibly bound to the aggregated polyglutamine protein.

We confirmed recruitment of the proteasome using a second expanded polyglutamine protein in primary neuronal cultures. Cerebellar neurons were transfected with an expression construct that encodes green fluorescent protein (GFP) fused to a glutamine tract of 80 residues derived from the DRPLA protein, atrophin (29). In transfected neurons, GFP-Q80 readily formed cytoplasmic aggregates and the proteasome co-localized to many but not all such aggregates (Fig. 2B, compare upper and lower panels). In Cos-7 cells, GFP-Q80 aggregates also caused redistribution of the proteasome (not shown). Our results with two distinct expanded polyglutamine proteins, together with similar findings in SCA1 (19), indicate that proteasome recruitment is likely to be generally true of polyglutamine aggregates.

Full-length mutant ataxin-3 forms NI that recruit the proteasome and correspond to promyelocytic leukemia antigen (PML) oncogenic domains (PODs)

Compared with Q78, full-length ataxin-3 with 78 repeats is relatively poor at forming aggregates in cells. In our hands, full-length ataxin-3 with a normal or expanded repeat (27 or 78 residues) usually remains diffusely distributed in transfected Cos-7, HeLa or 293 cells (25,27,30). Most of the expressed ataxin-3 is found in the cytoplasm, with only a small amount in the nucleus. Intriguingly, however, in the few cells where full-length mutant ataxin-3 does form aggregates (<1% of transfected cells), the inclusions are found exclusively within the nucleus. Thus, in an effort to promote aggregate formation by the full-length protein, we targeted ataxin-3 to the nucleus by adding a nuclear localization signal (NLS) to the N-terminus of the protein. Addition of an NLS resulted in a redistribution of ataxin-3 into the nucleus (Fig. 3). In HeLa cells, NLS-ataxin-3 with a non-pathogenic repeat of 27 residues localized diffusely to the nucleus with rare exceptions (Fig. 3A). In contrast, NLS-ataxin-3 with 78 repeats formed NI in 20-40% of transfected cells. A subset of these NI sequestered the proteasome (Fig. 3B). The results demonstrate that the full-length disease protein is capable of forming intranuclear aggregates that lead to a redistribution of the proteasome.


Figure 3. Nuclear targeted, full-length ataxin-3(Q78) forms NI that recruit the proteasome and correspond to PODs. Shown are HeLa cells expressing myc-tagged full-length ataxin-3 that has been targeted to the nucleus by the addition of an NLS to the protein. (A and B) Co-immunofluorescence for NLS-myc-ataxin-3 and the proteasome. (A) NLS-myc-ataxin-3 with a non-pathogenic repeat (27 residues) localizes diffusely to the nucleus (arrow). (B) In contrast, NLS-myc-ataxin-3 with an expanded glutamine repeat (78 residues) forms NI in a subset of transfected cells. The 20S proteasome core (red) redistributes into many but not all NI (green) that are formed by mutant ataxin-3 [upper and lower panels in (B) show NI to which the proteasome does (upper) or does not (lower) co-localize.] (C and D) Co-immunofluorescence for NLS-myc-ataxin-3 and PML antigen. (C) NLS-myc-ataxin-3(27) localizes diffusely to the nucleus and cytoplasm (green) with no clear relationship to PODs (red). (D) NLS-myc-ataxin-3(78) forms nuclear inclusions (green) that co-localize to PODs (red), confirmed by coincident staining in the merged image. [DAPI staining of nuclei (blue) is shown in the left panels of (A) and (B), the middle panels of (C) and (D) and the merged images of (A), (C) and (D).]

We wished to determine whether NI formed by full-length ataxin-3 resided within particular subnuclear structures. This has been shown to be the case for aggregates formed by the SCA1 disease protein, ataxin-1 (31). In transfected cells, mutant ataxin-1 forms inclusions that co-localize to PODs, also known as nuclear domain 10 (ND10) domains (32). In cells transfected with nuclear targeted mutant ataxin-3, staining for PML confirmed that ataxin-3 NI also co-localized to PODs (Fig. 3C and D). Further immunofluorescence studies confirmed that these ataxin-3/POD structures were clearly distinct from other subnuclear domains including nucleoli, coiled bodies, gem structures and DNA replication domains (data not shown).

Proteasome inhibition increases polyglutamine aggregation

The redistribution of proteasomes into polyglutamine aggregates suggested to us that proteasome function might play a critical role in the disease process. One possibility is that proteasome recruitment into NI represents an effort by the cell to ‘handle’ misfolded polyglutamine protein. For example, the proteasome may serve to recognize and eliminate misfolded polyglutamine protein, thereby reducing aggregate formation. To determine if this might be the case, we tested whether inhibitors of the proteasome could promote polyglutamine aggregation. For these experiments, we chose to use a glutamine repeat that is capable of forming aggregates, but less efficiently than Q78. We took advantage of a truncated ataxin-3 construct that contains an intermediate length repeat of 49 glutamine residues (Q49) generated by PCR. A repeat length of 49 falls squarely in the gap between normal and disease repeat length distributions for SCA3/MJD (20). Although shorter than the shortest repeat known to cause SCA3/MJD, a repeat of 49 residues is well within the pathologic range for many polyglutamine diseases, including HD, SCA1, SBMA and SCA2. In transfected HeLa cells, HA-Q49 typically showed a diffuse staining pattern, forming aggregates only infrequently (<5% of cells in each of four experiments). Treatment of transfected HeLa or Cos-7 cells with the specific proteasome inhibitor lactacystin (33) led to a marked increase in Q49 aggregate formation, both intranuclear and perinuclear (Fig. 4). This increased aggregate formation occurred in a glutamine repeat length-dependent manner, since aggregation was not increased in cells expressing Q27 (Fig. 4A and B) or GFP fused to polyglutamine domains of 19 or 35 glutamine residues (data not shown). As expected, aggregation of Q78 occurred readily even in the absence of lactacystin and was not further increased by inhibiting the proteasome (Fig. 4B). In the presence of lactacystin, the 20S proteasome core still redistributed into aggregates even though the proteasome’s proteolytic activity was inhibited. Quantitation of cell death indicated that lactacystin-induced aggregate formation did not cause increased cell death in HeLa cells (data not shown).

   A
   B - E

Figure 4. Inhibiting the proteasome promotes polyglutamine aggregation. Treating transfected HeLa or Cos-7 cells with the specific proteasome inhibitor lactacystin causes a marked increase in polyglutamine aggregation that is dependent upon repeat length. (A) Immunofluorescence of Cos-7 cells transfected with HA-Q27 or HA-Q49 and incubated with or without lactacystin (controls were treated with the carrier, DMSO). In cells expressing the intermediate repeat length ataxin-3 fragment HA-Q49, but not in cells expressing HA-Q27, lactacystin causes a marked increase in intranuclear and cytoplasmic aggregation. (The arrow identifies a Q49-expressing cell that has both intranuclear aggregates and diffuse cytoplasmic staining.) (B) Quantitation of lactacystin-induced aggregation by HA-Q27, HA-Q49 and HA-Q78 in HeLa cells (10 µM lactacystin for 24 h). Note that HA-Q78 efficiently forms aggregates even under control conditions. (C) Dose dependence of lactacystin-induced aggregation. HeLa cells expressing HA-Q49 were incubated for 24 h with the indicated concentrations of lactacystin and scored for aggregate formation. (D) Time dependence of aggregate formation. Aggregation in Cos-7 cells expressing HA-Q49 was quantitated at the indicated times after lactacystin was added. (E) Aggregate formation is not increased by inhibitors of lysosomal proteases. Aggregation was quantitated in HeLa cells for 24 h after addition of the indicated protease inhibitors. lac, lactacystin; leup, leupeptin; chlor, chloroquine. In (B) and (C), results are the means of two separately performed experiments; in (D) and (E), results are from single representative experiments.


Figure 5. Lactacystin treatment causes an increase in SDS-insoluble polyglutamine aggregation. Shown are immunoblots of lysates from transfected HeLa cells incubated in the absence or presence of lactacystin. (A) Equal lysates from control cells and cells expressing HA-Q49 or HA-Q78 were examined by immunoblot with anti-HA antisera. In the presence of lactacystin, HA-Q49 forms SDS-insoluble complexes that migrate in the stacking gel (brackets). Note that HA-Q78 forms insoluble complexes even under control conditions and these are not measurably increased by lactacystin treatment. (B) Lactacystin causes a marked increase in high molecular weight aggregates of HA-Q49 (arrowhead) which sediment in the insoluble fraction. Fractionation of lysates into soluble and insoluble fractions was carried out before immunoblot analysis with anti-HA antisera. In (A) and (B), arrows indicate monomeric Q49 protein.

Aggregate formation was promoted by lactacystin in a dose- and time-dependent manner (Fig. 4C and D). Although doses of lactacystin >10 µM were equally or more effective at promoting aggregation, cells showed signs of cytotoxicity to lactacystin at these higher concentrations (20 and 50 µM). Two additional proteasome inhibitors, ALLN and MG132, also increased aggregate formation but caused significant cytotoxicity and thus were not further used (data not shown). Increased aggregate formation appears to be specific to inhibitors of the proteasome since aggregation was not increased by inhibitors of lysosomal proteases (Fig. 4E).

Immunoblot analysis confirmed that, in lactacystin-treated cells, Q49 aggregates resembled aggregates formed by the pathogenic Q78 fragment (25): both were insoluble to boiling, reducing agents and SDS treatment and both migrated in the stack of SDS gels (Fig. 5A and B). Cell fractionation experiments confirmed that Q49 aggregates sedimented in the insoluble fraction (Fig. 5B). Immunoblots also indicated that total Q49 protein levels did not increase dramatically in lactacystin-treated cells. This fact argues against a potentially trivial explanation for increased aggregate formation: a simple rise in the intracellular concentration of Q49 that might be expected to drive the protein toward aggregation.

Importantly, lactacystin also promoted aggregation by full-length mutant ataxin-3. In the presence of lactacystin, NLS-myc-ataxin-3 with a 78 glutamine repeat formed extensive cytoplasmic and intranuclear aggregates in most cells (data not shown), whereas under control conditions it formed exclusively nuclear inclusions in 20-40% of transfected cells (as illustrated in Fig. 3B and D). The formation of cytoplasmic aggregates despite the presence of an NLS in the protein suggests that lactacystin caused NLS-ataxin-3(78) to aggregate before it could be transported to the nucleus, essentially trapping the protein in the cytoplasm.

DISCUSSION

Redistribution of the 26S proteasome complex into NI in SCA3/MJD brain and cellular models implicates the ubiquitin-proteasome degradation pathway in SCA3/MJD pathogenesis. Together with similar findings in SCA1 (19), the results presented here suggest that proteasome involvement may be generalized to most if not all polyglutamine diseases. They further support the view that expanded polyglutamine domains promote misfolding of the disease protein, resulting in aggregation. Moreover, our finding that proteasome inhibition accelerates aggregate formation implies that the proteasome may play a direct role in modulating aggregation in the disease state.

A fundamental question prompted by our results is: does proteasome redistribution into polyglutamine aggregates represent an appropriate and beneficial response by the cell or is it rather a pathologic event that has deleterious consequences for the cell? The fact that proteasome inhibitors increase polyglutamine aggregation favors the view that the proteasome represents a first-line cellular defense to recognize and eliminate misfolded polyglutamine protein before it aggregates. The simplest model to explain our results with proteasome inhibitors is that, under normal conditions, the proteasome selectively degrades misfolded, expanded polyglutamine protein, thereby reducing the concentration of aggregation-prone polypeptide. Since polyglutamine aggregation is likely to proceed through a nucleation step that is dependent upon the concentration of misfolded protein (6,34; E. Wanker, personal communication), this function of the proteasome would reduce the rate of aggregation. When proteasome activity is blocked with lactacystin or other inhibitors, the concentration of misfolded polyglutamine protein would increase, favoring nucleation and aggregation. Alternatively, proteasome inhibitors could increase polyglutamine aggregation indirectly through effects on other cellular proteins or metabolic pathways. Currently it is unknown whether polyglutamine misfolding or the resultant aggregation is the fundamental pathogenic event in disease. However, based on our model, enhancing proteasome activity within disease neurons would be expected to reduce both potentially pathogenic processes.

Our results are further consistent with a model in which the proteasome also acts upon polyglutamine protein after it has formed aggregates, perhaps further processing the aggregated polypeptide. An intriguing hypothesis, one that is still consistent with a separate beneficial role for the proteasome, is that expanded polyglutamine protein directly inhibits the proteasome to which it is targeted. Inhibition of the proteasome by expanded polyglutamine would decrease cellular levels of functioning proteasomes. Our lactacystin results suggest that this, in turn, would further promote aggregation in a deleterious feed-forward manner. How might expanded polyglutamine inhibit the proteasome? To be degraded by the proteasome a protein must first be unfolded in order to enter the central proteolytic chamber. Expanded polyglutamine may form a highly stable [beta]-sheet hairpin structure (4) that resists unfolding and thus blocks entrance to the chamber. A similar model has been proposed for [beta]-amyloid effects on the proteasome (35). In vitro reconstitution experiments clearly will be required to determine whether expanded polyglutamine does in fact inhibit the proteasome.

A much debated issue in polyglutamine diseases (36,37) is whether NI are pathogenic structures, bystanders in disease or perhaps even beneficial to the cell (38). Recent studies in SCA1 transgenic mice have shown that macroscopic aggregates are not necessary for initiating disease pathogenesis (39). Whether, however, aggregates contribute to later stages of disease remains unknown. It is important to note that neurological symptoms in polyglutamine diseases progress over decades, suggesting that at the cellular level there may be an initial and prolonged period of neuronal dysfunction before a later period of neuronal demise. Our current view of polyglutamine pathogenesis is that it is a multistep process in which misfolding of the disease protein is central to all steps of disease, including the early period of neuronal dysfunction, but in which macroscopic intranuclear aggregates are late participants, contributing principally to the final period of neuronal demise. The tools are now in hand to test directly the role of aggregation in neurons. The ability to increase aggregation by inhibiting the proteasome (this study) or to decrease aggregation by overexpressing certain chaperonins (19; Y. Chai and H. Paulson, unpublished data) should now allow researchers to determine whether modulating polyglutamine aggregation has a beneficial or deleterious effect on neurons. Moreover, as modifier genes are identified through genetic screens in invertebrate models of disease (9,40), the precise role of cellular chaperone systems, including chaperonins and the 26S proteasome complex, in polyglutamine diseases may become clear.

The results presented here indicate previously unrecognized similarities between SCA3/MJD and SCA1 that may have broader implications for the entire class of polyglutamine diseases. First, studies of both diseases now show that the full-length disease proteins are capable of forming inclusions, provided the protein is resident within the nucleus. The finding of aggregation by the full protein suggests that proteolysis may not be necessary to drive the misfolding and aggregation that occurs in disease. Secondly, nuclear inclusions formed by full-length ataxin-1 and ataxin-3 both reside in a specific subnuclear domain known as PODs or ND10 domains. The function of PODs is unclear, but recent studies suggest they may mediate certain forms of cell death, in part through the recruitment of other proteins (41,42). The relationship of NI to PODs in other polyglutamine diseases clearly will need to be pursued. Thirdly, the nuclear environment appears to promote aggregation of both disease proteins; when present in the cytoplasm, mutant forms of ataxin-1 and ataxin-3 do not form detectable aggregates (25,27,39). Fourthly, the proteasome and certain cellular chaperone proteins redistribute into NI formed by the two disease proteins, both in vivo and in vitro (19; this study and unpublished data). Despite these unifying features there are still important differences, the most obvious being a difference in the normal subcellular distribution of the two proteins. Ataxin-1 is almost exclusively nuclear in neurons (43), whereas ataxin-3 shows a variable cytoplasmic and nuclear pattern of expression (25-27,30,44-46). Our results suggest the possibility that even though most ataxin-3 protein in neurons is cytoplasmic (25,26), some is nuclear, and it is this intranuclear pool of ataxin-3 that precipitates disease. It will thus be critical to identify the factors regulating nuclear transport of ataxin-3 and to address, in vivo, the importance of nuclear localization that the present cell-based studies of ataxin-3 suggest.

Finally, the role of proteasomes in neurodegenerative diseases extends beyond the polyglutamine diseases. Many inherited and acquired neurodegenerative diseases are proteinopathies, diseases in which a particular protein or set of proteins misfold and aggregate (17,18). Ubiquitin stains proteinaceous deposits in many classes of neurodegenerative disease, including Alzheimer’s disease and other dementias, Parkinson’s disease, prion diseases, motor neuron disease and, of course, polyglutamine diseases (47,48). Moreover, the proteasome localizes to pathological structures in most of these diseases (19,49,50). Despite the clear differences between these diseases, perturbations of the proteasome degradation pathway may represent a common link. To this end, manipulations of proteasome function may prove to be of therapeutic use not only in the polyglutamine diseases, but in other neurodegenerative diseases as well.

MATERIALS AND METHODS

Expression plasmids

The ataxin-3 expression constructs pJ3M-ataxin-3(Q27), pcDNA3-myc-ataxin-3(Q78), pcDNA3-HA-Q27, pcDNA3-HA-Q78 and pJ3M-Q78 were described previously (25,30). PCDNA3-HA-Q49 was derived by PCR amplification of the C-terminus of ataxin-3(Q78) during which a spontaneous reduction in CAG repeat size occurred. Automated DNA sequencing (University of Iowa DNA Facility) confirmed that pCDNA3-HA-Q49 was identical to pCDNA3-HA-Q78 except for its shorter repeat of 49 residues. Expression vectors pAG-NLS-myc-ataxin-3(Q27) and pAG-NLS-myc-ataxin-3(Q78) contain full-length ataxin-3 cDNA modified to contain an NLS at the N-terminus (the NLS sequence is MPKKKRK). These modified cDNAs were generated by PCR and cloned into pAG-3, an expression vector in which the expressed cDNA is tagged at the C-terminus with a myc-hexahistidine epitope tag (51). To generate NLS constructs, we used the forward primer (5[prime]-GGATCCACCATGCCCAAGAAGAAGCGGAAGGTCGAG TCCATCTTCC ACGAGAAACAA GAAGGC-3[prime]) and the reverse primer (5[prime]-GCGGCCGCTCTGTCAGATAAAGTGTGAAGGTAGC-3[prime]). The GFP-polyglutamine fusion constructs with Q19, Q35 or Q80 repeats (29) were generously provided by W. Strittmatter (Durham, NC).

Cell culture and transfection

HeLa cells were grown in minimum essential medium (MEM) and Cos-7 cells and 293 cells were maintained in Dulbecco’s modified Eagle’s medium (DMEM) (Gibco BRL, Grand Island, NY). All cell lines were supplemented with 10% fetal calf serum, 100 U/ml penicillin-500 µg/ml streptomycin (Gibco BRL) and HeLa cells were also supplemented with 1% MEM non-essential amino acid solution (Sigma, St Louis, MO). For transient transfections, 50% confluent 35 mm dishes of HeLa, Cos-7 or 293 cells were transfected with 1 µg of expression plasmid DNA using Lipofectamine PLUS reagent (Gibco Life Technologies, Gaithersburg, MD). Twenty-four hours after transfection, cells were transferred to chamber slides coated with 0.1% gelatin/phosphate-buffered saline (PBS) for an additional 24 h before immunofluorescence.

For transfection of cultured neurons, cerebella were removed from 3-day-old Sprague-Dawley rat pups, incubated in dissociation medium twice for 30 min each (52), triturated with a 5 ml pipette and centrifuged at 300 g for 5 min. The pellet was resuspended in Earle’s salts with 3 mg bovine serum albumin (BSA), 3 mg ovomucoid and 300 U DNase, then carefully added to 5 ml BSA/ovomucoid (10 mg/ml) and centrifuged at 70 g for 6 min. The pelleted, dissociated neurons were resuspended in DMEM, 10% calf serum, 10% Ham’s F-12, Pen/Strep/Fungizone and plated onto polyornithine-coated glass coverslips in 6-well chamber dishes at a density of 5 × 106 cells/dish. The cultures were treated with cytosine-[beta]-d-arabinofuranoside on the second day after seeding and then transfected on day 3 using an established calcium phosphate precipitation protocol for cortical neurons (53) with the following modifications: 4 µg DNA/well was used and kynurenic acid or APV were not included in the transfection.

Protease inhibitor treatment

Three or twenty-four hours after transfection, cells were incubated with the indicated proteasome or lysosomal inhibitors for 24 h or, in the experiment in Figure 4D, for the indicated lengths of time. Control cells were incubated with equivalent amounts of the carrier agent, dimethyl sulfoxide (DMSO). The results shown in the experiments in Figure 4 are from representative experiments duplicated at least twice in all cases. The proteasome inhibitors lactacystin and MG-132 were from Calbiochem (La Jolla, CA). The non-specific proteasome/lysosomal protease inhibitor N-acetyl-leucinyl-leucyl-norleucinal (ALLN) and lysosomal inhibitors leupeptin, E64 and chloroquine were from Sigma. Unless otherwise stated the concentrations used were: 10 µM lactacystin, 10 µM E64, 10 µM MG-132, 15 µM ALLN and 25 µM chloroquine. To confirm that 10 µM lactacystin inhibited proteasome function, we performed anti-ubiquitin immunoblots on lysates, which documented increases in total ubiquitinated protein consistent with the expected failure in degradation.

Immunocytochemistry

Forty-eight hours after transfection, cells were washed with PBS, fixed for 15 min with 4% formaldehyde/PBS, permeabilized with 0.05% Triton X-100, blocked for 15 min with 5% normal goat serum in 0.05% Triton X-100/PBS and incubated for 60 min at 37°C with primary antibody. Subsequently, cells were incubated for 60 min with either anti-mouse-FITC/anti-rabbit-TRITC or anti-rabbit-FITC/anti-mouse-TRITC (1:1000) (Jackson Immuno-Research Laboratories, West Grove, PA). After extensive washing, chamber slides were counterstained for 10 min in 0.05% Triton X-100/PBS containing 4,6-diamidino-2-phenylindole (DAPI) (2 µg/ml) (Sigma) and mounted in SlowFade (Molecular Probes, Eugene, OR). Samples were observed with a Zeiss Axioplan fluorescence microscope under 630× magnification and digitized images were collected on separate fluorescence channels using a Diagnostics SPOT digital camera. Digitized images were assembled using Adobe Photoshop.

The 20S proteasome was detected by immunostaining with rabbit polyclonal anti-20S proteasome antibody (1:1,000) (a gift of W. Ward, University of Texas, San Antonio, TX). Immunostaining for other proteins of the ubiquitin-proteasome pathway were assessed using antibodies from Affiniti (Exeter, UK) with dilutions in parentheses: rabbit polyclonal antibodies against the ATPase subunit TBP7 of the human 19S proteasome regulator (1:200), ubiquitin C-terminal hydrolase (1:200), ubiquitin conjugating enzyme E2 (1:200) and subunit PA28a of 11S proteasome regulator (1:1000). Antibody to the 19S cap protein, ubiquitin isopeptidase Uch37 (28), was generously provided by R. Cohen and W. Xu (University of Iowa, Iowa City, IA) and used at 1:200 dilution. Ataxin-3 constructs were detected with anti-HA monoclonal antibody (12CA5, 1:500) (Boehringer Mannheim, Indianapolis, IN), anti-HA or anti-myc polyclonal antibody (1:500 and 1:250, respectively) (Santa Cruz Biotechnology, Santa Cruz, CA) or anti-myc monoclonal antibody 9E10 (1:500) (a gift of R. Deschenes, University of Iowa). PML was detected with anti-PML monoclonal antibody at 1:100 dilution (Santa Cruz Biotechnology) and polyclonal antibody at 1:1000 (a gift of K.-S. Chang, M.D. Anderson Cancer Center, Houston, TX). Coiled bodies were detected with human anti-p80-coilin serum (a gift of E. Chan, The Scripps Research Institute, La Jolla, CA), gems were detected with monoclonal anti-gem antibody (a gift of G. Dreyfuss, University of Pennsylvania, Philadelphia, PA), DNA replication domains were detected with mouse monoclonal RPA32 and RPA70 antibodies (a gift of M. Wold, University of Iowa) and nucleoli were detected with human serum 41 and 42 (a gift of G. Maul, University of Pennsylvania).

Immunohistochemistry

The SCA3/MJD brain tissue used in this study was as previously described (25,30). Positive immunohistochemical findings were confirmed in a second SCA3/MJD brain. Control brain sections (kindly provided by S. Moore, University of Iowa) were from a normal 40-year-old male who died an accidental death. Immunostaining was performed on 6 µM paraffin sections as previously described (25,30) except that the diaminobenzidine (DAB) histochemical reaction was carried out using FAST DAB tablets (Sigma) and no counterstain was used. Concentrations of antisera were 1:2000 for anti-20S, 1:200 for anti-TBP7 and anti-PA28 and 1:100 for anti-ubiquitin monoclonal antibody (Zymed, San Francisco, CA).

Quantitation of aggregates and cell viability

Quantitation of aggregates in transfected cells was carried out by an observer blind to the treatment conditions. Starting from a random point on the chamber slide, a systematic sweep across the slide was carried out under fluorescein or rhodamine illumination and all transfected cells were scored by their staining pattern as diffusely labeled or as containing aggregates. Typically >200 cells were counted per experimental sample per experiment. The percentage of cells with aggregates was obtained by dividing the number of cells with aggregates by the total number of transfected cells.

Cell viability was quantitated as previously described (25) in Cos cells 48 h after co-transfection with [beta]-galactosidase and truncated ataxin-3 constructs (HA-Q27 or HA-Q49). Cells were incubated with or without 10 µM lactacystin for the final 24 h and parallel dishes of cells were immunocytochemically stained to verify that lactacystin treatment led to aggregate formation in HA-Q49, but not HA-Q27, transfected cells. We previously showed that HA-Q78 expression caused a roughly 4-fold increase in the rate of apoptotic cell death (25). In contrast, Q49 expression did not lead to an increase above the background death in Q27-expressing cells or control cells in the presence or absence of lactacystin treatment.

Immunoblot and cell fractionation studies

Transfected HeLa cells were harvested directly into 1× SDS loading buffer (50 mM Tris pH 6.8, 100 mM dithiothreitol, 2% SDS, 0.1% bromophenol blue, 10% glycerol), sonicated briefly and heated to 95°C for 5 min. Equal amounts of protein were electrophoresed on discontinuous 12% polyacrylamide gels (SDS-PAGE) and the gels were transblotted to PVDF membranes. Membranes were blocked for 2 h in blocking solution (10% non-fat powdered milk, 10% glycerol, 0.2% Tween-20 in PBS), incubated for 2 h with primary polyclonal anti-HA antibody Y-11 (Santa Cruz Biotechnology) at a dilution of 1:1000 or anti-20S proteasome antisera at 1:2000, washed five timesin blocking solution and incubated for 1 h with peroxidase-conjugated goat anti-rabbit antisera (1:15 000). Bands were visualized using enhanced chemiluminescence (Amersham, Piscataway, NJ).

For cell fractionation studies, transfected cells were solubilized for 20 min on ice in non-denaturing lysis buffer (0.5% NP-40, 0.9% NaCl, 0.02 M HEPES, 1 mM EDTA, supplemented with protease inhibitors phenylmethylsulfonyl fluoride, leupeptin and pepstatin A). After vortexing, samples were centrifuged for 10 min at 12 000 g. The supernatant (soluble fraction) was then transferred to a separate tube. The insoluble pellet was incubated in additional lysis buffer for 10 min, sonicated briefly and repelleted. This second pellet represented the insoluble fraction. Equal amounts of protein from soluble and insoluble fractions were denatured in Laemmli buffer with DTT and electrophoresed by 12% SDS-PAGE.

ACKNOWLEDGEMENTS

We thank N. Bonini and P. Opal for comments on the manuscript and R. Pittman for his generosity with reagents and advice. We also thank E. Chan, K.-S. Chang, R. Cohen, R. Deschenes, G. Dreyfuss, J. Kraft, G. Maul, W. Ward, M. Wold and W. Xu for generously providing antisera, and K. Campbell and his laboratory for advice and assistance with graphics. We also thank the University of Iowa Pathology Core Laboratory for assistance with tissue processing. This work was supported by grants to H.L.P. from the Roy J. Carver Charitable Trust and the American Academy of Neurology.

ABBREVIATIONS

ALLN, N-acetyl-leucinyl-leucyl-norleucinal; BSA, bovine serum albumin; DAB, diaminobenzidine; DAPI, 4,6-diamidino-2-phenylindole; DMEM, Dulbecco’s modified Eagle’s medium; DMSO, dimethyl sulfoxide; GFP, green fluorescence protein; HA, hemagglutinin; MEM, minimum essential medium; MJD, Machado-Joseph disease; ND10, nuclear domain 10; NI, intranuclear inclusions; NLS, nuclear localization signal; PBS, phosphate-buffered saline; PML, promyelocytic leukemia antigen; PODs, PML oncogenic domains; SCA, spinocerebellar ataxia.

REFERENCES

1. Koshy, B.T. and Zoghbi, H.Y. (1997) The CAG/polyglutamine tract diseases: gene products and molecular pathogenesis. Brain Pathol., 7, 927-942.

2. Hackam, A.S., Wellington, C.L and Hayden, M.R. (1998) The fatal attraction of polyglutamine-containing proteins. Clin. Genet., 53, 233-242. MEDLINE Abstract

3. Lunkes, A. and Mandel, J.L. (1997) Polyglutamines, nuclear inclusions and neurodegeneration. Nature Med., 3, 1201-1202. MEDLINE Abstract

4. Perutz, M.F., Johnson, T., Suzuki, M. and Finch, J.T. (1994) Glutamine repeats as polar zippers: their possible role in inherited neurologic diseases. Proc. Natl Acad. Sci. USA, 91, 5355-5358. MEDLINE Abstract

5. Trottier, Y., Lutz, Y., Stevanin, G., Imbert, G., Devys, D. et al). (1995) Polyglutamine expansion as a pathological epitope in Huntington's disease and four dominant cerebellar ataxias. Nature, 378, 403-406. MEDLINE Abstract

6. Scherzinger, E., Lurz, R., Turmaine, M., Mangiarini, L., Hollenbach, B., Hasenvank, R., Bates, G.P., Davies, S.W., Lehrach, H. and Wanker, E.E. (1997) Huntingtin-encoded polyglutamine expansions form amyloid-like protein aggregates in vitro and in vivo. Cell, 90, 549-558. MEDLINE Abstract

7. Ross, C. (1997) Intranuclear neuronal inclusions: a common pathogenic mechanism for glutamine-repeat neurodegenerative diseases? Neuron, 19, 1147-1150. MEDLINE Abstract

8. Davies, S.W., Beardsall, K., Turmaine, M., DiFiglia, M., Aronin, N. and Bates, G.P. (1998). Are neuronal intranuclear inclusions the common neuropathology of triplet-repeat disorders with polyglutamine-repeat expansion? Lancet, 351, 131-133. MEDLINE Abstract

9. Warrick, J.M., Paulson, H.L., Gray-Board, G., Bui, Q.T., Fischbeck, K.H., Pittman, R.N. and Bonini, N.M. (1998) Expanded polyglutamine protein forms nuclear inclusions and causes neural degeneration in Drosophila. Cell, 93, 939-949. MEDLINE Abstract

10. Holmberg, M., Duyckaerts, C., Durr, A., Cancel, G., Gourfinkel-An, I., Damier, P., Faucheux, B., Trottier, Y., Hirsch, E.C., Agid, Y. and Brice, A. (1998) Spinocerebellar ataxia type 7 (SCA7): a neurodegenerative disorder with neuronal intranuclear inclusions. Hum. Mol. Genet., 7, 913-918. MEDLINE Abstract

11. Li, M., Miwa, S., Kobayashi, Y., Merry, D., Yamamoto, M., Tanaka, F., Doyu, M., Hashizume, Y., Fischbeck, K.H. and Sobue, G. (1998) Nuclear inclusions of the androgen receptor protein in spinal and bulbar muscular atrophy. Ann. Neurol., 44, 249-254. MEDLINE Abstract

12. Ciechanover, A. (1997) The ubiquitin-proteasome proteolytic pathway. Cell, 79, 13-21.

13. Mengual, E., Arizti, P., Rodrigo, J., Gimenez-Amaya, J.M. and Castano, J.G. (1996) Immmunohistochemical distribution and electron microscopic subcellular localization of the proteasome in the rat CNS. J. Neurosci., 16, 6331-6341. MEDLINE Abstract

14. Sadoul, R., Fernandez, P.A., Quiquerez, A.L., Marinou, I., Maki, M. et al). (1996) Involvement of the proteasome in the programmed cell death of NGF-deprived sympathetic neurons. EMBO J., 15, 3845-3852. MEDLINE Abstract

15. Leroy, E., Boyer, R., Auburger, G., Leube, B., Ulm, G., Mezey, E., Harta, G., Brownstein, M.J., Jonnalagada, S., Chernova, T., Dehejia, A., Lavedan, C., Gasser, T., Steinbach, P.J., Wilkinson, K.D. and Polymeropoulos, M.H. (1998) The ubiquitin pathway in Parkinson's disease. Nature, 395, 451-452. MEDLINE Abstract

16. Jiang, Y.H., Armstrong, D., Albrecht, U., Atkins, C.M., Noebels, J.L., Eichele, G., Sweatt, J.D. and Beaudet, A.L. (1998) Mutation of the Angelman ubiquitin ligase in mice causes increased cytoplasmic p53 and deficits of contextual learning and long-term potentiation. Neuron, 21, 799-811. MEDLINE Abstract

17. Hardy, J. and Gwinn-Hardy, K. (1998) Genetic classification of primary neurodegenerative disease. Science, 282, 1075-1079. MEDLINE Abstract

18. Kakizuka, A. (1998) Protein precipitation: a common etiology in neurodegenerative disorders? Trends Genet., 14, 396-402. MEDLINE Abstract

19. Cummings, C.J., Mancini, M.A., Antalffy, B., DeFranco, D.B., Orr, H.T. and Zoghbi, H.Y. (1998) Chaperone suppression of ataxin-1 aggregation and altered subcellular proteosome localization imply protein misfolding in SCA1. Nature Genet., 19, 148-154. MEDLINE Abstract

20. Paulson, H.L. (1998) Analysis of Triplet Repeat Disorders: Spinocerebellar Ataxia Type 3/Machado-Joseph Disease. BIOS Scientific Publishers, Oxford, UK.

21. Kawaguchi, Y., Okamoto, T., Taniwaki, M., Aizawa, M., Inoue, M., Katayama, H., Nakamura, S., Nishimura, M., Akiguchi, I., Kimura, J., Narumiya, S. and Kakizuka, A. (1994) CAG expansions in a novel gene for Machado-Joseph disease at chromosome 14q32.1. Nature Genet., 8, 221-228. MEDLINE Abstract

22. Yuasa, T., Ohama, E., Harayama, H., Yamada, M., Kawase, Y., Wakabayashi, M., Atsumi, T. and Miyatake, T. (1986) Joseph's disease: clinical and pathological studies in a Japanese family. Ann. Neurol., 19, 152-157. MEDLINE Abstract

23. Sachdev, H.S., Forno L.S. and Kane, C.A. (1982) Joseph disease: a multisystem degenerative disorder of the nervous system. Neurology, 32, 192-195. MEDLINE Abstract

24. Takiyama, Y., Oyanagi, S., Kawashima, S., Sakamoto, H., Saito, K. et al). (1994) A clinical and pathologic study of a large Japanese family with Machado-Joseph disease tightly linked to the DNA markers on chromosome 14q. Neurology, 44, 1302-1308. MEDLINE Abstract

25. Paulson, H.L., Perez, M.K., Trottier, Y., Trojanowski, J.Q., Subramony, S.H., Das, S.S., Vig, P., Mandel, J.L., Fischbeck, K.H. and Pittman, R.N. (1997) Intranuclear inclusions of expanded polyglutamine protein in spinocerebellar ataxia type 3. Neuron, 19, 333-344. MEDLINE Abstract

26. Schmidt, T., Landwehrmeyer, B., Schmitt, I., Trottier, Y., Auburger, G., Laccone, F., Klockgether, T., Völpel, M., Epplen, J.T., Schöls, L. and Riess, O. (1998) An isoform of ataxin-3 accumulates in the nucleus of neuronal cells in affected brain regions of SCA3 patients. Brain Pathol., 8, 669-679.

27. Perez, M., Paulson, H., Pendse, S., Saionz, S., Bonini, N. and Pittman, R. (1998) Recruitment and the role of nuclear localization in polyglutamine-mediated aggregation. J. Cell. Biol., 143, 1457-1470. MEDLINE Abstract

28. Lam, Y.A., Xu, W., DeMartino, G.N. and Cohen, R.E. (1997) Editing of ubiquitin conjugates in the 26S proteasome. Nature, 385, 737-740. MEDLINE Abstract

29. Onodera, O., Burke, J.R., Miller, S.E., Hester, S., Tsuji, S. et al). (1997) Oligomerization of expanded-polyglutamine domain fluorescent fusion proteins in cultured mammalian cells. Biochem. Biophys. Res. Commun., 238, 599-605. MEDLINE Abstract

30. Paulson, H.L., Das, S.S., Crino, P.B., Perez, M.K., Patel, S.C., Gotsdiner, D., Fischbeck, K.H. and Pittman, R.N. (1997) Machado-Joseph disease gene product is a cytoplasmic protein expressed widely in brain. Ann. Neurol., 41, 453-462. MEDLINE Abstract

31. Skinner, P.J., Koshy, B.T., Cummings, C.J., Klement, I.A., Helin, K., Servadio, A., Zoghbi, H.Y. and Orr, H.T. (1997) Ataxin-1 with an expanded glutamine tract alters nuclear matrix-associated structures. Nature, 389, 971-974. MEDLINE Abstract

32. Lamond, A.I. and Earnshaw, W.C. (1998) Structure and function in the nucleus. Science, 280, 547-553. MEDLINE Abstract

33. Fenteany, G., Standaert, R.F., Lane, W.S., Choi, S., Corey, E.J. and Schreiber, S.L. (1995) Inhibition of proteasome activities and subunit-specific amino-terminal threonine modification by lactacystin. Science, 268, 726-731. MEDLINE Abstract

34. Lansbury, P.T. Jr (1997) Structural neurology: are seeds at the root of neuronal degeneration? Neuron, 19, 1151-1154. MEDLINE Abstract

35. Gregori, L., Fuchs, C., Figueiredo-Pereira, M.E., Van Nostrand, W.E. and Goldgaber, D. (1995) Amyloid [beta]-protein inhibits ubiquitin-dependent protein degradation in vitro. J. Biol. Chem., 270, 19702-19708. MEDLINE Abstract

36. Sisodia, S.S. (1998) Nuclear inclusions in glutamine repeat disorders: are they pernicious, coincidental, or beneficial? Cell, 95, 1-4. MEDLINE Abstract

37. Kim, T.W. and Tanzi, R.E. (1998) Neuronal intranuclear inclusions in polyglutamine diseases: nuclear weapons or nuclear fallout? Neuron, 21, 657-659. MEDLINE Abstract

38. Saudou, F., Finkbeiner, S., Devys, D. and Greenberg, M.E. (1998) Huntingtin acts in the nucleus to induce apoptosis but death does not correlate with the formation of intranuclear inclusions. Cell, 95, 55-66. MEDLINE Abstract

39. Klement, I.A., Skinner, P.J., Kaytor, M.D., Yi, H., Hersch, S.M., Clark, H.B., Zoghbi, H.Y. and Orr, H.T. (1998) Ataxin-1 nuclear localization and aggregation: role in polyglutamine-induced disease in SCA1 transgenic mice. Cell, 95, 41-53. MEDLINE Abstract

40. Jackson, G.R., Salecker, I., Dong, X., Yao, X., Arnheim, N., Faber, P.W., MacDonald, M.E. and Zipursky, S.L. (1998) Polyglutamine-expanded human huntingtin transgenes induce degeneration of Drosophila photoreceptor neurons. Neuron, 21, 633-642. MEDLINE Abstract

41. Quignon, F., De Bels, F., Koken, M., Feunteun, J., Ameisen, J.C. and de The, H. (1998) PML induces a novel caspase-independent death process. Nature Genet., 20, 259-265. MEDLINE Abstract

42. Wang, Z.G., Ruggero, D., Ronchetti, S., Zhong, S., Gaboli, M., Rivi, R. and Pandolfi, P.P. (1998) Pml is essential for multiple apoptotic pathways. Nature Genet., 20, 266-272. MEDLINE Abstract

43. Servadio, A., Koshy, B., Armstrong, D., Antalffy, B., Orr, H.T. and Zoghbi, H.Y. (1995) Expression analysis of the ataxin-1 protein in tissues from normal and spinocerebellar ataxia type 1 individuals. Nature Genet., 10, 94-98. MEDLINE Abstract

44. Ikeda, H., Yamaguchi, M., Sugai, S., Aze, Y., Narumiya, S. and Kakizuka, A. (1996) Expanded polyglutamine in the Machado-Joseph disease protein induces cell death in vitro and in vivo. Nature Genet., 13, 196-202. MEDLINE Abstract

45. Tait, D., Riccio, M., Sittler, A., Scherzinger, E., Santi, S., Ognibene, A., Maraldi, N.M., Lehrach, H. and Wanker, E.E. (1998) Ataxin-3 is transported into the nucleus and associates with the nuclear matrix. Hum. Mol. Genet., 7, 991-997. MEDLINE Abstract

46. Wang, G., Keiko, I., Nukina, N. et al). (1997) Machado-Joseph disease gene product identified in lymphocytes and brain. Biochem. Biophys. Res. Commun., 233, 476-479. MEDLINE Abstract

47. Gai, W.P., Blessing, W.W. and Blumbergs, P.C. (1995) Ubiquitin-positive degenerating neurites in the brainstem in Parkinson's disease. Brain, 118, 1447-1459. MEDLINE Abstract

48. Lowe, J., Mayer, R.J. and Landon, M. (1993). Ubiquitin in neurodegenerative diseases. Brain Pathol., 3, 55-65.

49. Fergusson, J., Landon, M., Lowe, J., Dawson, S.P., Layfield, R., Hanger, D.P. and Mayer, R.J. (1996) Pathological lesions of Alzheimer's disease and dementia with Lewy bodies brains exhibit immunoreactivity to an ATPase that is a regulatory subunit of the 26S proteasome. Neurosci. Lett., 219, 167-170. MEDLINE Abstract

50. Ii, K., Ito, H., Tanaka, K. and Hirano, A. (1997) Immunocytochemical colocalization of the proteasome in ubiquitinated structures in neurodegenerative diseases and the elderly. J. Neuropathol. Exp. Neurol., 56, 125-131. MEDLINE Abstract

51. Koppel, A.M., Feiner, L., Kobayashi, H. and Raper, J.A. (1997) A 70 amino acid region within the semaphorin domain activates specific cellular response of semaphorin family members. Neuron, 19, 531-537. MEDLINE Abstract

52. Furshpan, E.J. and Potter, D.D. (1989) Seizure-like activity and cellular damage in rat hippocampal neurons in cell culture. Neuron, 3, 199-207. MEDLINE Abstract

53. Xia, Z., Dudek, H., Miranti, C.K. and Greenberg, M.E. (1996) Calcium influx via the NMDA receptor induces immediate early gene transcription by a MAP kinase/ERK-dependent mechanism. J. Neurosci., 16, 5425-5436. MEDLINE Abstract

*To whom correspondence should be addressed. Tel: +1 319 335 8696; Fax: +1 319 356 4505; Email: henry-paulson{at}uiowa.edu

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Home page
 J. Neurosci.Home page
E. S. Chevalier-Larsen, C. J. O'Brien, H. Wang, S. C. Jenkins, L. Holder, A. P. Lieberman, and D. E. Merry
Castration Restores Function and Neurofilament Alterations of Aged Symptomatic Males in a Transgenic Mouse Model of Spinal and Bulbar Muscular Atrophy
J. Neurosci., May 19, 2004; 24(20): 4778 - 4786.
[Abstract] [Full Text] [PDF]

Home page
 ScienceHome page
J. S. Steffan, N. Agrawal, J. Pallos, E. Rockabrand, L. C. Trotman, N. Slepko, K. Illes, T. Lukacsovich, Y.-Z. Zhu, E. Cattaneo, et al.
SUMO Modification of Huntingtin and Huntington's Disease Pathology
Science, April 2, 2004; 304(5667): 100 - 104.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
P. Gonzalez-Alegre and H. L. Paulson
Aberrant Cellular Behavior of Mutant TorsinA Implicates Nuclear Envelope Dysfunction in DYT1 Dystonia
J. Neurosci., March 17, 2004; 24(11): 2593 - 2601.
[Abstract] [Full Text] [PDF]

Home page
 J BiochemHome page
K. Shimoke, H. Amano, S. Kishi, H. Uchida, M. Kudo, and T. Ikeuchi
Nerve Growth Factor Attenuates Endoplasmic Reticulum Stress-Mediated Apoptosis via Suppression of Caspase-12 Activity
J. Biochem., March 1, 2004; 135(3): 439 - 446.
[Abstract] [Full Text] [PDF]

Home page
 Physiol. GenomicsHome page
J. L. Griffin, C. K. Cemal, and M. A. Pook
Defining a metabolic phenotype in the brain of a transgenic mouse model of spinocerebellar ataxia 3
Physiol Genomics, February 13, 2004; 16(3): 334 - 340.
[Abstract] [Full Text] [PDF]

Home page
 Nucleic Acids ResHome page
V. M. Miller, C. M. Gouvion, B. L. Davidson, and H. L. Paulson
Targeting Alzheimer's disease genes with RNA interference: an efficient strategy for silencing mutant alleles
Nucleic Acids Res., January 30, 2004; 32(2): 661 - 668.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
Y. Chai, S. S. Berke, R. E. Cohen, and H. L. Paulson
Poly-ubiquitin Binding by the Polyglutamine Disease Protein Ataxin-3 Links Its Normal Function to Protein Surveillance Pathways
J. Biol. Chem., January 30, 2004; 279(5): 3605 - 3611.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
M. Diaz-Hernandez, F. Hernandez, E. Martin-Aparicio, P. Gomez-Ramos, M. A. Moran, J. G. Castano, I. Ferrer, J. Avila, and J. J. Lucas
Neuronal Induction of the Immunoproteasome in Huntington's Disease
J. Neurosci., December 17, 2003; 23(37): 11653 - 11661.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
B. Burnett, F. Li, and R. N. Pittman
The polyglutamine neurodegenerative protein ataxin-3 binds polyubiquitylated proteins and has ubiquitin protease activity
Hum. Mol. Genet., December 1, 2003; 12(23): 3195 - 3205.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
H. Scheel, S. Tomiuk, and K. Hofmann
Elucidation of ataxin-3 and ataxin-7 function by integrative bioinformatics
Hum. Mol. Genet., November 1, 2003; 12(21): 2845 - 2852.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
A. Abu-Baker, C. Messaed, J. Laganiere, C. Gaspar, B. Brais, and G. A. Rouleau
Involvement of the ubiquitin-proteasome pathway and molecular chaperones in oculopharyngeal muscular dystrophy
Hum. Mol. Genet., October 16, 2003; 12(20): 2609 - 2623.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
J. L. Marsh, J. Pallos, and L. M. Thompson
Fly models of Huntington's disease
Hum. Mol. Genet., October 15, 2003; 12(90002): R187 - 193.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
K. M. Donaldson, W. Li, K. A. Ching, S. Batalov, C.-C. Tsai, and C. A. P. Joazeiro
Ubiquitin-mediated sequestration of normal cellular proteins into polyglutamine aggregates
PNAS, July 22, 2003; 100(15): 8892 - 8897.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
D. P. Huynh, H.-T. Yang, H. Vakharia, D. Nguyen, and S. M. Pulst
Expansion of the polyQ repeat in ataxin-2 alters its Golgi localization, disrupts the Golgi complex and causes cell death
Hum. Mol. Genet., July 1, 2003; 12(13): 1485 - 1496.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
K.J. Cowan, M.I. Diamond, and W.J. Welch
Polyglutamine protein aggregation and toxicity are linked to the cellular stress response
Hum. Mol. Genet., June 15, 2003; 12(12): 1377 - 1391.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
V. M. Miller, H. Xia, G. L. Marrs, C. M. Gouvion, G. Lee, B. L. Davidson, and H. L. Paulson
Allele-specific silencing of dominant disease genes
PNAS, June 10, 2003; 100(12): 7195 - 7200.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
Y. C. Tsai, P. S. Fishman, N. V. Thakor, and G. A. Oyler
Parkin Facilitates the Elimination of Expanded Polyglutamine Proteins and Leads to Preservation of Proteasome Function
J. Biol. Chem., June 6, 2003; 278(24): 22044 - 22055.
[Abstract] [Full Text] [PDF]

Home page
 J. Cell Sci.Home page
W.-J. Wang, S. Mulugeta, S. J. Russo, and M. F. Beers
Deletion of exon 4 from human surfactant protein C results in aggresome formation and generation of a dominant negative
J. Cell Sci., February 15, 2003; 116(4): 683 - 692.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
J. L. Walcott and D. E. Merry
Ligand Promotes Intranuclear Inclusions in a Novel Cell Model of Spinal and Bulbar Muscular Atrophy
J. Biol. Chem., December 20, 2002; 277(52): 50855 - 50859.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
H.Y. E. Chan, J. M. Warrick, I. Andriola, D. Merry, and N. M. Bonini
Genetic modulation of polyglutamine toxicity by protein conjugation pathways in Drosophila
Hum. Mol. Genet., November 1, 2002; 11(23): 2895 - 2904.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
K. Mitsui, H. Nakayama, T. Akagi, M. Nekooki, K. Ohtawa, K. Takio, T. Hashikawa, and N. Nukina
Purification of Polyglutamine Aggregates and Identification of Elongation Factor-1alpha and Heat Shock Protein 84 as Aggregate-Interacting Proteins
J. Neurosci., November 1, 2002; 22(21): 9267 - 9277.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
P. Kazemi-Esfarjani and S. Benzer
Suppression of polyglutamine toxicity by a Drosophila homolog of myeloid leukemia factor 1
Hum. Mol. Genet., October 2, 2002; 11(21): 2657 - 2672.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
H. Kita, J. Carmichael, J. Swartz, S. Muro, A. Wyttenbach, K. Matsubara, D. C. Rubinsztein, and K. Kato
Modulation of polyglutamine-induced cell death by genes identified by expression profiling
Hum. Mol. Genet., September 15, 2002; 11(19): 2279 - 2287.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
A. P. Lieberman, G. Harmison, A. D. Strand, J. M. Olson, and K. H. Fischbeck
Altered transcriptional regulation in cells expressing the expanded polyglutamine androgen receptor
Hum. Mol. Genet., August 15, 2002; 11(17): 1967 - 1976.
[Abstract] [Full Text] [PDF]

Home page
 Mol. Cell. Biol.Home page
K. L. B. Borden
Pondering the Promyelocytic Leukemia Protein (PML) Puzzle: Possible Functions for PML Nuclear Bodies
Mol. Cell. Biol., August 1, 2002; 22(15): 5259 - 5269.
[Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
Y. Chai, J. Shao, V. M. Miller, A. Williams, and H. L. Paulson
Live-cell imaging reveals divergent intracellular dynamics of polyglutamine disease proteins and supports a sequestration model of pathogenesis
PNAS, July 9, 2002; 99(14): 9310 - 9315.
[Abstract] [Full Text] [PDF]

Home page
 BrainHome page
J. Takahashi, H. Fujigasaki, C. Zander, K. H. El Hachimi, G. Stevanin, A. Durr, A.-S. Lebre, G. Yvert, Y. Trottier, H. d. The, et al.
Two populations of neuronal intranuclear inclusions in SCA7 differ in size and promyelocytic leukaemia protein content
Brain, July 1, 2002; 125(7): 1534 - 1543.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
C. K. Bailey, I. F. M. Andriola, H. H. Kampinga, and D. E. Merry
Molecular chaperones enhance the degradation of expanded polyglutamine repeat androgen receptor in a cellular model of spinal and bulbar muscular atrophy
Hum. Mol. Genet., March 1, 2002; 11(5): 515 - 523.
[Abstract] [Full Text] [PDF]

Home page
 BrainHome page
J. T. Pang, P. Giunti, S. Chamberlain, S. F. An, R. Vitaliani, T. Scaravilli, L. Martinian, N. W. Wood, F. Scaravilli, and O. Ansorge
Neuronal intranuclear inclusions in SCA2: a genetic, morphological and immunohistochemical study of two cases
Brain, March 1, 2002; 125(3): 656 - 663.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
W. J. Welch and M. I. Diamond
Glucocorticoid modulation of androgen receptor nuclear aggregation and cellular toxicity is associated with distinct forms of soluble expanded polyglutamine protein
Hum. Mol. Genet., December 1, 2001; 10(26): 3063 - 3074.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
E. Martin-Aparicio, A. Yamamoto, F. Hernandez, R. Hen, J. Avila, and J. J. Lucas
Proteasomal-Dependent Aggregate Reversal and Absence of Cell Death in a Conditional Mouse Model of Huntington's Disease
J. Neurosci., November 15, 2001; 21(22): 8772 - 8781.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
A. Matilla, C. Gorbea, D. D. Einum, J. Townsend, A. Michalik, C. van Broeckhoven, C. C. Jensen, K. J. Murphy, L. J. Ptacek, and Y.-H. Fu
Association of ataxin-7 with the proteasome subunit S4 of the 19S regulatory complex
Hum. Mol. Genet., November 1, 2001; 10(24): 2821 - 2831.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Pathol.Home page
M. Yamada, T. Sato, T. Shimohata, S. Hayashi, S. Igarashi, S. Tsuji, and H. Takahashi
Interaction between Neuronal Intranuclear Inclusions and Promyelocytic Leukemia Protein Nuclear and Coiled Bodies in CAG Repeat Diseases
Am. J. Pathol., November 1, 2001; 159(5): 1785 - 1795.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
B. O. Evert, I. R. Vogt, C. Kindermann, L. Ozimek, R. A. I. de Vos, E. R. P. Brunt, I. Schmitt, T. Klockgether, and U. Wullner
Inflammatory Genes Are Upregulated in Expanded Ataxin-3-Expressing Cell Lines and Spinocerebellar Ataxia Type 3 Brains
J. Neurosci., August 1, 2001; 21(15): 5389 - 5396.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
N. R. Jana, E. A. Zemskov, G.-h. Wang, and N. Nukina
Altered proteasomal function due to the expression of polyglutamine-expanded truncated N-terminal huntingtin induces apoptosis by caspase activation through mitochondrial cytochrome c release
Hum. Mol. Genet., May 1, 2001; 10(10): 1049 - 1059.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
A.-S. Lebre, L. Jamot, J. Takahashi, N. Spassky, C. Leprince, N. Ravise, C. Zander, H. Fujigasaki, P. Kussel-Andermann, C. Duyckaerts, et al.
Ataxin-7 interacts with a Cbl-associated protein that it recruits into neuronal intranuclear inclusions
Hum. Mol. Genet., May 1, 2001; 10(11): 1201 - 1213.
[Abstract] [Full Text] [PDF]

Home page
 Mol. Biol. CellHome page
S. Waelter, A. Boeddrich, R. Lurz, E. Scherzinger, G. Lueder, H. Lehrach, and E. E. Wanker
Accumulation of Mutant Huntingtin Fragments in Aggresome-like Inclusion Bodies as a Result of Insufficient Protein Degradation
Mol. Biol. Cell, May 1, 2001; 12(5): 1393 - 1407.
[Abstract] [Full Text]

Home page
 Genes Dev.Home page
H. T. Orr
Beyond the Qs in the polyglutamine diseases
Genes & Dev., April 15, 2001; 15(8): 925 - 932.
[Full Text]

Home page
 Hum Mol GenetHome page
H.Y. E. Chan, J. M. Warrick, G. L. Gray-Board, H. L. Paulson, and N. M. Bonini
Mechanisms of chaperone suppression of polyglutamine disease: selectivity, synergy and modulation of protein solubility in Drosophila
Hum. Mol. Genet., November 1, 2000; 9(19): 2811 - 2820.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
G. Yvert, K. S. Lindenberg, S. Picaud, G. B. Landwehrmeyer, J.-A. Sahel, and J.-L. Mandel
Expanded polyglutamines induce neurodegeneration and trans-neuronal alterations in cerebellum and retina of SCA7 transgenic mice
Hum. Mol. Genet., October 1, 2000; 9(17): 2491 - 2506.
[Abstract] [Full Text] [PDF]

Home page
 JCBHome page
J. D. Wood, F. C. Nucifora Jr., K. Duan, C. Zhang, J. Wang, Y. Kim, G. Schilling, N. Sacchi, J. M. Liu, and C. A. Ross
Atrophin-1, the Dentato-Rubral and Pallido-Luysian Atrophy Gene Product, Interacts with Eto/Mtg8 in the Nuclear Matrix and Represses Transcription
J. Cell Biol., September 4, 2000; 150(5): 939 - 948.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
A. McCampbell, J. P. Taylor, A. A. Taye, J. Robitschek, M. Li, J. Walcott, D. Merry, Y. Chai, H. Paulson, G. Sobue, et al.
CREB-binding protein sequestration by expanded polyglutamine
Hum. Mol. Genet., September 1, 2000; 9(14): 2197 - 2202.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
A. Calado, F. M.S. Tome, B. Brais, G.A. Rouleau, U. Kuhn, E. Wahle, and M. Carmo-Fonseca
Nuclear inclusions in oculopharyngeal muscular dystrophy consist of poly(A) binding protein 2 aggregates which sequester poly(A) RNA
Hum. Mol. Genet., September 1, 2000; 9(15): 2321 - 2328.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
N. R. Jana, M. Tanaka, G.-h. Wang, and N. Nukina
Polyglutamine length-dependent interaction of Hsp40 and Hsp70 family chaperones with truncated N-terminal huntingtin: their role in suppression of aggregation and cellular toxicity
Hum. Mol. Genet., August 12, 2000; 9(13): 2009 - 2018.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
C. J. Cummings and H. Y. Zoghbi
Fourteen and counting: unraveling trinucleotide repeat diseases
Hum. Mol. Genet., April 1, 2000; 9(6): 909 - 916.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
Y. Kobayashi, A. Kume, M. Li, M. Doyu, M. Hata, K. Ohtsuka, and G. Sobue
Chaperones Hsp70 and Hsp40 Suppress Aggregate Formation and Apoptosis in Cultured Neuronal Cells Expressing Truncated Androgen Receptor Protein with Expanded Polyglutamine Tract
J. Biol. Chem., March 17, 2000; 275(12): 8772 - 8778.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
A. Wyttenbach, J. Carmichael, J. Swartz, R. A. Furlong, Y. Narain, J. Rankin, and D. C. Rubinsztein
Effects of heat shock, heat shock protein 40 (HDJ-2), and proteasome inhibition on protein aggregation in cellular models of Huntington's disease
PNAS, March 14, 2000; 97(6): 2898 - 2903.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
S. Krobitsch and S. Lindquist
Aggregation of huntingtin in yeast varies with the length of the polyglutamine expansion and the expression of chaperone proteins
PNAS, February 15, 2000; 97(4): 1589 - 1594.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
M. I. Diamond, M. R. Robinson, and K. R. Yamamoto
Regulation of expanded polyglutamine protein aggregation and nuclear localization by the glucocorticoid receptor
PNAS, January 18, 2000; 97(2): 657 - 661.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
M. D. Kaytor and S. T. Warren
Aberrant Protein Deposition and Neurological Disease
J. Biol. Chem., December 31, 1999; 274(53): 37507 - 37510.
[Full Text] [PDF]

Home page
 J. Neurosci.Home page
Y. Chai, S. L. Koppenhafer, N. M. Bonini, and H. L. Paulson
Analysis of the Role of Heat Shock Protein (Hsp) Molecular Chaperones in Polyglutamine Disease
J. Neurosci., December 1, 1999; 19(23): 10338 - 10347.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
B. O. Evert, U. Wullner, J. B. Schulz, M. Weller, P. Groscurth, Y. Trottier, A. Brice, and T. Klockgether
High level expression of expanded full-length ataxin-3 in vitro causes cell death and formation of intranuclear inclusions in neuronal cells
Hum. Mol. Genet., July 1, 1999; 8(7): 1169 - 1176.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
S.-H. Li, A. L. Cheng, H. Li, and X.-J. Li
Cellular Defects and Altered Gene Expression in PC12 Cells Stably Expressing Mutant Huntingtin
J. Neurosci., July 1, 1999; 19(13): 5159 - 5172.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
Y. Chai, L. Wu, J. D. Griffin, and H. L. Paulson
The Role of Protein Composition in Specifying Nuclear Inclusion Formation in Polyglutamine Disease
J. Biol. Chem., November 21, 2001; 276(48): 44889 - 44897.
[Abstract] [Full Text] [PDF]

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