Identifying polyglutamine protein species in situ that best predict neurodegeneration

Miller, Jason; Arrasate, Montserrat; Brooks, Elizabeth D.; Libeu, Clare Peters; Legleiter, Justin; Hatters, Danny M.; Curtis, Jessica; Cheung, Katherine; Krishnan, Preethi; Mitra, Siddhartha; Widjaja, Kartika; Shaby, Benjamin A.; Lotz, Gregor P.; Newhouse, Yvonne M.; Mitchell, Emily J; Osmand, Alex; Gray, Michelle; Thulasiramin, Vanitha; Saudou, Frédéric; Segal, Mark R.; Yang, X. William; Masliah, Eliezer; Thompson, Leslie M.; Muchowski, Paul J.; Weisgraber, Karl H.; Finkbeiner, Steven

doi:10.1038/nchembio.694

Cited by 190 publications

(192 citation statements)

References 51 publications

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“…Some have suggested that the inclusion bodies themselves containing aggregated protein fragments are not so pernicious (45). Instead, the toxicity of small oligomeric species of mutant protein fragments that have adopted specific conformational states may be critical (46,47). Arrasate et al (48) have shown that, rather than the total HTT level determining cell death, the amount of diffuse intracellular HTT predicts whether cell death occurs.…”

Section: Discussionmentioning

confidence: 99%

Aggregation landscapes of Huntingtin exon 1 protein fragments and the critical repeat length for the onset of Huntington’s disease

Chen

Wolynes

2017

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

104

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Huntington's disease (HD) is a neurodegenerative disease caused by an abnormal expansion in the polyglutamine (polyQ) track of the Huntingtin (HTT) protein. The severity of the disease depends on the polyQ repeat length, arising only in patients with proteins having 36 repeats or more. Previous studies have shown that the aggregation of N-terminal fragments (encoded by HTT exon 1) underlies the disease pathology in mouse models and that the HTT exon 1 gene product can self-assemble into amyloid structures. Here, we provide detailed structural mechanisms for aggregation of several protein fragments encoded by HTT exon 1 by using the associative memory, water-mediated, structure and energy model (AWSEM) to construct their free energy landscapes. We find that the addition of the N-terminal 17-residue sequence (NT 17 ) facilitates polyQ aggregation by encouraging the formation of prefibrillar oligomers, whereas adding the C-terminal polyproline sequence (P 10 ) inhibits aggregation. The combination of both terminal additions in HTT exon 1 fragment leads to a complex aggregation mechanism with a basic core that resembles that found for the aggregation of pure polyQ repeats using AWSEM. At the extrapolated physiological concentration, although the grand canonical free energy profiles are uphill for HTT exon 1 fragments having 20 or 30 glutamines, the aggregation landscape for fragments with 40 repeats has become downhill. This computational prediction agrees with the critical length found for the onset of HD and suggests potential therapies based on blocking early binding events involving the terminal additions to the polyQ repeats.Huntington's disease | aggregation | solubility | aggregation free energy landscape | critical length H untingtin (HTT) is a huge protein (3,100 amino acid residues) that has been implicated in a variety of physiological functions (1, 2). Having an expanded polyglutamine (polyQ) region of 36 or more glutamine residues in the N terminus of HTT leads to Huntington's disease as witnessed by the deposition of large intracellular protein aggregates or inclusion bodies, which are comprised primarily of N-terminal fragments coded by the exon 1 sequence of the mutant HTT (2-5). These N-terminal fragments, each composed of an N-terminal 17-residue sequence (NT17), a polyQ sequence that has expanded in length, and a proline-rich region afterward, originate from proteolysis of HTT (2, 3). The aggregation of the HTT exon 1 product is, therefore, believed to cause Huntington's disease. Clinical studies have shown an inverse correlation between polyQ length and age of disease onset (5). By implicating polymer physics in the disease process, this regularity has intrigued biophysicists for decades.Expanded polyQ sequences, more generally, are associated with nine known neurodegenerative diseases (4). Biophysical chemists have, therefore, focused on first understanding the aggregation of pure polyQ peptides. The rate of aggregation of polyQ peptides is length-dependent, and primary nucleation is rate-limiti...

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Section: Discussionmentioning

confidence: 99%

Aggregation landscapes of Huntingtin exon 1 protein fragments and the critical repeat length for the onset of Huntington’s disease

Chen

Wolynes

2017

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

104

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“…For polyQ-containing proteins, oligomers form before IBs, their formation is polyQ length-dependent, and their presence is well correlated with cell death (25,37). Both chaperones that remodel oligomers and peptides that inhibit oligomer formation suppress toxicity (38,39).…”

Section: Discussionmentioning

confidence: 99%

Prion-like proteins sequester and suppress the toxicity of huntingtin exon 1

Kayatekin

Matlack

Hesse

et al. 2014

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

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Expansions of preexisting polyglutamine (polyQ) tracts in at least nine different proteins cause devastating neurodegenerative diseases. There are many unique features to these pathologies, but there must also be unifying mechanisms underlying polyQ toxicity. Using a polyQ-expanded fragment of huntingtin exon-1 (Htt103Q), the causal protein in Huntington disease, we and others have created tractable models for investigating polyQ toxicity in yeast cells. These models recapitulate key pathological features of human diseases and provide access to an unrivalled genetic toolbox. To identify toxicity modifiers, we performed an unbiased overexpression screen of virtually every protein encoded by the yeast genome. Surprisingly, there was no overlap between our modifiers and those from a conceptually identical screen reported recently, a discrepancy we attribute to an artifact of their overexpression plasmid. The suppressors of Htt103Q toxicity recovered in our screen were strongly enriched for glutamine-and asparagine-rich prion-like proteins. Separated from the rest of the protein, the prion-like sequences of these proteins were themselves potent suppressors of polyQ-expanded huntingtin exon-1 toxicity, in both yeast and human cells. Replacing the glutamines in these sequences with asparagines abolished suppression and converted them to enhancers of toxicity. Replacing asparagines with glutamines created stronger suppressors. The suppressors (but not the enhancers) coaggregated with Htt103Q, forming large foci at the insoluble protein deposit in which proteins were highly immobile. Cells possessing foci had fewer (if any) small diffusible oligomers of Htt103Q. Until such foci were lost, cells were protected from death. We discuss the therapeutic implications of these findings.protein misfolding | prions P rotein misfolding and aggregation underlie many neurodegenerative diseases. The causes of protein misfolding are numerous and include single amino acid changes and expansions of amino acid repeats. Polyglutamine (polyQ) expansions are an infamous example of the latter and are responsible for at least nine neurodegenerative conditions, including Huntington disease (HD). In most of these diseases the polyQ-expanded protein is expressed throughout the body, but tissue damage is restricted to the nervous system and, often, to a subset of cells depending on the causal protein. Thus, there are important cell type-specific determinants of toxicity, and these are specific to particular proteins. Despite these differences, disease severity is tightly linked to the number of glutamines. Progressively earlier onset occurs as the number of glutamines increases beyond a critical threshold of ∼35-45 residues (1). Moreover, in all cases, pathology is associated with misfolded forms of the polyQ-expanded protein.Thus, common features that arise from the expansions and result from shared aspects of polyQ-driven protein misfolding must contribute to pathology. Given the diverse nature of both the proteins bearing the polyQ tract and t...

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“…To detect soluble HTTex1Q49 molecules we used the monoclonal antibody 3B5H10, which exclusively recognizes expanded polyQ tracts in soluble HTT molecules (Miller et al 2011). An analysis of time-resolved HTTex1Q49 aggregation assays with dot-blot assays revealed that soluble 3B5H10-reactive HTT molecules disappeared at a slower rate in the presence of wild-type CRMP1 than in the presence of mutant CRMP1-D408V (Fig.…”

Section: Crmp1 Directly Targets Mutant Htt Fragments and Reduces Theimentioning

confidence: 99%

“…Alternatively, evidence has been provided that the toxic species in HD may be diffusible oligomeric or protofibrillar HTT aggregates with pathogenic polyQ tracts (Hands and Wyttenbach 2010). In contrast to large inclusion bodies, these smaller structures are described as highly mobile and able to associate with numerous cellular proteins, leading to abnormal protein-protein interactions and dysfunction of a range of important cellular processes (Miller et al 2011).…”

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confidence: 99%

Systematic interaction network filtering identifies CRMP1 as a novel suppressor of huntingtin misfolding and neurotoxicity

et al. 2015

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Assemblies of huntingtin (HTT) fragments with expanded polyglutamine (polyQ) tracts are a pathological hallmark of Huntington's disease (HD). The molecular mechanisms by which these structures are formed and cause neuronal dysfunction and toxicity are poorly understood. Here, we utilized available gene expression data sets of selected brain regions of HD patients and controls for systematic interaction network filtering in order to predict disease-relevant, brain region-specific HTT interaction partners. Starting from a large protein-protein interaction (PPI) data set, a step-by-step computational filtering strategy facilitated the generation of a focused PPI network that directly or indirectly connects 13 proteins potentially dysregulated in HD with the disease protein HTT. This network enabled the discovery of the neuron-specific protein CRMP1 that targets aggregation-prone, N-terminal HTT fragments and suppresses their spontaneous self-assembly into proteotoxic structures in various models of HD. Experimental validation indicates that our network filtering procedure provides a simple but powerful strategy to identify disease-relevant proteins that influence misfolding and aggregation of polyQ disease proteins.

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Identifying polyglutamine protein species in situ that best predict neurodegeneration

Cited by 190 publications

References 51 publications

Aggregation landscapes of Huntingtin exon 1 protein fragments and the critical repeat length for the onset of Huntington’s disease

Aggregation landscapes of Huntingtin exon 1 protein fragments and the critical repeat length for the onset of Huntington’s disease

Prion-like proteins sequester and suppress the toxicity of huntingtin exon 1

Systematic interaction network filtering identifies CRMP1 as a novel suppressor of huntingtin misfolding and neurotoxicity

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