Formation of morphologically similar globular aggregates from diverse aggregation-prone proteins in mammalian cells

Mukai, Hideyuki; Isagawa, T.; Goyama, Emiko; Tanaka, Shuhei; Bence, Neil; Tamura, Atsuo; Ono, Yoshitaka; Kopito, Ron R.

doi:10.1073/pnas.0409283102

Cited by 67 publications

(47 citation statements)

References 42 publications

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“…2, E-H). These observations are consistent with other reports of polyglutamine fibrils identified in the insoluble material from mice expressing htt exon 1 (22) and oligomers and fibrils that form in vitro (25,38). We further characterized the oligomers present on the mica using height distribution analysis on several 5-10-m 2 scan pictures (Fig.…”

Section: Soluble Aggregates Consist Of Formicsupporting

confidence: 79%

Soluble Androgen Receptor Oligomers Underlie Pathology in a Mouse Model of Spinobulbar Muscular Atrophy

Chevalier-Larsen

Merry

et al. 2007

Journal of Biological Chemistry

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In polyglutamine diseases such as X-linked spinobulbar muscular atrophy (SBMA), it is unknown whether the toxic form of the protein is an insoluble or soluble aggregate or a monomer. We have addressed this question by studying a full-length androgen receptor (AR) mouse model of SBMA. We used biochemistry and atomic force microscopy to immunopurify oligomers soluble after ultracentrifugation that are comprised of a single ϳ50-kDa N-terminal polyglutamine-containing AR fragment. AR oligomers appeared several weeks prior to symptom onset, were distinct and temporally dissociated from intranuclear inclusions, and disappeared rapidly after castration, which halts disease. This is the first demonstration of soluble AR oligomers in vivo and suggests that they underlie neurodegeneration in SBMA.Polyglutamine diseases such as X-linked spinobulbar muscular atrophy (SBMA) 2 derive from CAG codon repeats that exceed a crucial length. This creates elongated polyglutamine tracts in affected proteins and progressive neurologic dysfunction and neurodegeneration (1). SBMA results from expanded glutamine repeats in the N terminus of the androgen receptor (AR) protein (2, 3). It is characterized by slowly progressive lower motor neuron degeneration and mild sensory neuronopathy that predominates in males (4, 5) due to exposure to androgens (6, 7). Large intracellular inclusions containing AR are observed throughout the body and may be localized in the cytoplasm or nucleus, whereas large intranuclear inclusions accumulate preferentially in motor neurons (8 -10). Pathologically expanded polyglutamine protein fragments are clearly prone to misfolding and aggregation in vitro that respects the tight length-dependent disease threshold seen in vivo (11,12). Thus, protein misfolding and/or aggregation are very likely to underlie pathogenesis of SBMA and other polyglutamine diseases. In many experimental systems, however, large intracellular inclusions can be dissociated from neuronal toxicity, indicating that these structures are probably not the primary pathologic species (13)(14)(15)(16)(17)(18)(19).If large inclusions are not pathogenic, what then is the toxic species? Most cellular and animal studies indicate that expanded proteins either exist as monomers or accumulate as large macromolecular complexes that are unable to enter an SDS-polyacrylamide gel (20 -23). However, in vitro studies indicate clearly that polyglutamine proteins, like other amyloidogenic proteins, can form small, ordered oligomers (11, 24 -27), and the existence of toxic, submicroscopic aggregates or oligomers has been invoked as a cause of polyglutamine toxicity in vivo (27,28). The operative definition of such species has varied. We define oligomers here as submacromolecular structures (i.e. soluble after high speed centrifugation) comprised of ordered polyglutamine aggregates. As previously proposed by Taylor et al. (28), we contrast protein oligomers, which are defined primarily via biochemistry, from intracellular inclusions, which are defined via histopath...

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Section: Soluble Aggregates Consist Of Formicsupporting

confidence: 79%

Soluble Androgen Receptor Oligomers Underlie Pathology in a Mouse Model of Spinobulbar Muscular Atrophy

Chevalier-Larsen

Merry

et al. 2007

Journal of Biological Chemistry

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“…The repeat length dependence of K n* is the only known biophysical parameter paralleling the polyGln repeat length correlation with disease risk and thus continues to provide support for a role for aggregation in the disease process. It will remain premature to categorically rule out a disease role for polyGln aggregation (36) until the detailed chronology of appearance in disease tissue and cell models is established for the rich variety of aggregate morphologies, functionalities, and sizes known to be formed by polyGln proteins (37)(38)(39).…”

Section: Discussionmentioning

confidence: 99%

Polyglutamine aggregation nucleation: Thermodynamics of a highly unfavorable protein folding reaction

Bhattacharyya

Thakur

Wetzel

2005

Proc. Natl. Acad. Sci. U.S.A.

158

200

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Polyglutamine (polyGln) aggregation is implicated in the disease progression of Huntington's disease and other expanded CAG repeat diseases. PolyGln aggregation in vitro follows a simple nucleated growth polymerization pathway without apparent complications such as populated intermediates, alternative assembly pathways, or secondary nucleation phenomena. Previous analysis of the aggregation of simple polyGln peptides revealed that the critical nucleus (the number of monomeric units involved in the formation of an energetically unfavorable aggregation nucleus) is equal to one, suggesting that polyGln nucleation can be viewed as an unfavorable protein folding reaction. We provide here a method for experimentally determining the number of elongation growth sites per unit weight for any polyGln aggregate preparation, a key parameter required for completion of the nucleation kinetics analysis and determination of the thermodynamics of nucleation. We find that, for the polyGln peptide Q 47, the secondorder rate constant for fibril elongation is 11,400 liters͞mol per s, whereas K n*, the equilibrium constant for nucleation of aggregation, is remarkably small, equal to 2.6 ؋ 10 ؊9 . The latter value corresponds to a free energy of nucleus formation of ؉12.2 kcal͞mol, a value consistent with a highly unfavorable folding reaction. The methods introduced here should allow further analysis of the energetics of polyGln nucleus formation and accurate comparisons of the seeding capabilities of different fibril preparations, a task of increasing importance in the amyloid field.amyloid ͉ Huntington's disease ͉ nucleated growth polymerization ͉ nucleation free energy

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“…The intermediacy of stable, structured oligomers is a common feature of in vitro fibrillization by many disease-associated proteins, including α-synuclein 39,40 , huntingtin 41 and islet amyloid polypeptide 42,43 , as well as by fibril-forming proteins that are unrelated to disease 44 . Non-fibrillar aggregates have also been isolated from cell culture 45,46 , from the brains of animal models of AD 21,47 and from diseased human brains [48][49][50][51] . Annular pore-like aggregates have been observed during the in vitro fibrillogenesis of many well-characterized amyloid-forming proteins 52 .…”

Section: Protofibrils Are Early Intermediates In Fibril Formationmentioning

confidence: 99%

A century-old debate on protein aggregation and neurodegeneration enters the clinic

Lansbury

Lashuel

2006

Nature

630

495

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The correlation between neurodegenerative disease and protein aggregation in the brain has long been recognized, but a causal relationship has not been unequivocally established, in part because a discrete pathogenic aggregate has not been identified. The complexity of these diseases and the dynamic nature of protein aggregation mean that, despite progress towards understanding aggregation, its relationship to disease is difficult to determine in the laboratory. Nevertheless, drug candidates that inhibit aggregation are now being tested in the clinic. These have the potential to slow the progression of Alzheimer's disease, Parkinson's disease and related disorders and could, if administered presymptomatically, drastically reduce the incidence of these diseases. The clinical trials could also settle the century-old debate about causality.

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Formation of morphologically similar globular aggregates from diverse aggregation-prone proteins in mammalian cells

Cited by 67 publications

References 42 publications

Soluble Androgen Receptor Oligomers Underlie Pathology in a Mouse Model of Spinobulbar Muscular Atrophy

Soluble Androgen Receptor Oligomers Underlie Pathology in a Mouse Model of Spinobulbar Muscular Atrophy

Polyglutamine aggregation nucleation: Thermodynamics of a highly unfavorable protein folding reaction

A century-old debate on protein aggregation and neurodegeneration enters the clinic

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