The chaperonin TRiC blocks a huntingtin sequence element that promotes the conformational switch to aggregation

Tam, Stephen J.; Spiess, Christoph; Auyeung, William Churk-Nam; Joachimiak, Łukasz A.; Chen, Bryan; Poirier, Michelle A.; Frydman, Judith

doi:10.1038/nsmb.1700

Cited by 229 publications

(408 citation statements)

References 50 publications

Supporting

Mentioning

375

Contrasting

Unclassified

Order By: Relevance

“…The finding that exogenous ApiCCT1 r delivery can be taken up by cells and localizes to both the cytosol and nucleus are highly significant given that both compartments appear to contribute to pathogenic effects mediated by chronic mHTT expression (34), in particular nuclear accumulation of mHtt exerts toxic effects (1, 12, 17, 18). ApiCCT1 r may be directly interacting with mHtt to alter aggregation and toxicity, consistent with the previous finding that ApiCCT1 r can by itself suppress formation of insoluble mHtt aggregates and interacts with the first 17 amino acids of Htt, which regulates aggregation kinetics and other Htt functions (16). Given that toxicity is ameliorated in a cell model expressing full-length mHtt in which inclusions are not observed, it is likely that ApiCCT1 r exerts direct effects on mHtt-mediated phenotypes beyond interference with aggregation.…”

Section: Discussionsupporting

confidence: 75%

“…Previous studies demonstrated that overexpression of CCT1 can alter HD phenotypes in cell models of HD and that the apical subunit of yeast CCT1 (ApiCCT1 r ) alone interacts with recombinant mHtt in vitro and inhibits aggregation (15,16). Therefore, if exogenous delivery of ApiCCT1 r to cells could modulate intracellular aggregation and toxicity, the need for overexpression of the protein inside the cell would be circumvented and provide a rational option for delivery to the brain.…”

Section: Discussionmentioning

confidence: 99%

“…A genomewide RNAi screen in Caenorhabditis elegans identified six of the eight subunits of CCT (1, 2, 4-7) as suppressors of polyglutamine aggregation (12). CCT/TRiC expression also prevents mHtt aggregation in cell and yeast models of HD (13)(14)(15)(16). Further, overexpression of one subunit of the TRiC/CCT complex, CCT1, is sufficient to inhibit aggregation and reduce mHtt-mediated toxicity in mouse N2a neuronal cells (15).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Exogenous delivery of chaperonin subunit fragment ApiCCT1 modulates mutant Huntingtin cellular phenotypes

Sontag

Joachimiak

Tan

et al. 2013

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

Self Cite

View full text Add to dashboard Cite

Aggregation of misfolded proteins is characteristic of a number of neurodegenerative diseases, including Huntington disease (HD). The CCT/TRiC (chaperonin containing TCP-1/TCP-1 ring) chaperonin complex can inhibit aggregation and cellular toxicity induced by expanded repeat Huntingtin (mHtt) fragments. The substratebinding apical domain of CCT/TRiC subunit CCT1, ApiCCT1, is sufficient to inhibit aggregation of expanded repeat mHtt fragments in vitro, providing therapeutic promise for HD. However, a key hurdle in considering ApiCCT1 as a potential treatment is in delivery. Because ApiCCT1 has a region of similarity to the HIV Tat protein cell-transduction domain, we tested whether recombinant ApiCCT1 (ApiCCT1 r ) protein could enter cells following exogenous delivery and modulate an established panel of mHtt-mediated cell-based phenotypes. Cell fractionation studies demonstrate that exogenous ApiCCT1 r can penetrate cell membranes and can localize to the nucleus, consistent with a strategy that can target both cytosolic and nuclear pathogenic events in HD. ApiCCT1 r application does indeed modulate HD cellular phenotypes by decreasing formation of visible inclusions, fibrillar oligomers, and insoluble mHtt derived from expression of a truncated mHtt exon 1 fragment. ApiCCT1 r also delays the onset of inclusion body formation as visualized via live imaging. ApiCCT1 r reduces mHtt-mediated toxicity in immortalized striatal cells derived from full-length knock-in HD mice, suggesting that therapeutic benefit may extend beyond effects on aggregation. These studies provide the basis for a potentially robust and unique therapeutic strategy to target mHtt-mediated protein pathogenesis.

show abstract

Section: Discussionsupporting

confidence: 75%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Exogenous delivery of chaperonin subunit fragment ApiCCT1 modulates mutant Huntingtin cellular phenotypes

Sontag

Joachimiak

Tan

et al. 2013

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

Self Cite

View full text Add to dashboard Cite

show abstract

“…TRiC may play a role in suppressing Huntington's disease by decreasing huntingtin aggregate formation (Kitamura et al 2006;Tam et al 2009). If TRiC is to be used therapeutically in the clinic, it will be necessary to study human TRiC to further understand chaperonin functions inside human cells.…”

Section: Discussionmentioning

confidence: 99%

Human TRiC complex purified from HeLa cells contains all eight CCT subunits and is active in vitro

Knee

Sergeeva

King

2013

Cell Stress and Chaperones

View full text Add to dashboard Cite

Archaeal and eukaryotic cytosols contain group II chaperonins, which have a double-barrel structure and fold proteins inside a cavity in an ATP-dependent manner. The most complex of the chaperonins, the eukaryotic TCP-1 ring complex (TRiC), has eight different subunits, chaperone containing TCP-1 (CCT1-8), that are arranged so that there is one of each subunit per ring. Aspects of the structure and function of the bovine and yeast TRiC have been characterized, but studies of human TRiC have been limited. We have isolated and purified endogenous human TRiC from HeLa suspension cells. This purified human TRiC contained all eight CCT subunits organized into double-barrel rings, consistent with what has been found for bovine and yeast TRiC. The purified human TRiC is active as demonstrated by the luciferase refolding assay. As a more stringent test, the ability of human TRiC to suppress the aggregation of human γD-crystallin was examined. In addition to suppressing offpathway aggregation, TRiC was able to assist the refolding of the crystallin molecules, an activity not found with the lens chaperone, α-crystallin. Additionally, we show that human TRiC from HeLa cell lysate is associated with the heat shock protein 70 and heat shock protein 90 chaperones. Purification of human endogenous TRiC from HeLa cells will enable further characterization of this key chaperonin, required for the reproduction of all human cells.

show abstract

“…For instance, it was shown that the first 17 amino acids in HTT, which adopt an α-helical conformation, can initiate the spontaneous aggregation of pathogenic polyQ tracts in cell-free assays (Thakur et al 2009). The importance of this polyQ flanking sequence for HTT misfolding is supported by biochemical studies with a chaperonin, which directly binds to the first 17 amino acids of HTT and blocks the de novo aggregation of N-terminal HTT fragments (Tam et al 2009). Thus, proteins that directly associate with polyQ flanking regions appear to strongly influence the spontaneous polymerization of disease proteins.…”

mentioning

confidence: 96%

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

et al. 2015

View full text Add to dashboard Cite

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.

show abstract

The chaperonin TRiC blocks a huntingtin sequence element that promotes the conformational switch to aggregation

Cited by 229 publications

References 50 publications

Exogenous delivery of chaperonin subunit fragment ApiCCT1 modulates mutant Huntingtin cellular phenotypes

Exogenous delivery of chaperonin subunit fragment ApiCCT1 modulates mutant Huntingtin cellular phenotypes

Human TRiC complex purified from HeLa cells contains all eight CCT subunits and is active in vitro

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

Contact Info

Product

Resources

About