Tumorigenic Mutations in VHL Disrupt Folding In Vivo by Interfering with Chaperonin Binding

Feldman, Douglas E.; Spiess, Christoph; Howard, Daniel E.; Frydman, Judith

doi:10.1016/s1097-2765(03)00423-4

Cited by 100 publications

(142 citation statements)

References 37 publications

(2 reference statements)

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“…Thus, a specific function of CCT may be to protect against aggregation of hydrophobic β-sheets. Consistent with this proposal, CCT has been shown to bind hydrophobic β-strands in VHL 27 and interact with the WD40 family β-sheet rich proteins in vivo 28 . As polyQ repeats are known to form β-sheet structures in aggregates, CCT may have an essential role to trap β-sheet structures required for aggregate formation.…”

supporting

confidence: 55%

Cytosolic chaperonin prevents polyglutamine toxicity with altering the aggregation state

et al. 2006

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Proteins with expanded polyQ repeats are associated with at least nine neurodegenerative disorders including ataxins 1 and 3, Kennedy's disease, and Huntington's disease (HD) 1,2 . These diseases are dominantly inherited and although the polyQ-containing proteins are expressed widely in the brain, they result in selective neuronal death. There is a significant and striking correlation between the length of the polyQ repeat and pathology; longer repeats result in earlier onset and more severe symptoms with the threshold of approximately 40 glutamine residues. In the case of HD, for example, expanded polyQ in huntingtin (htt) protein causes disease 3,4 . A characteristic of the polyQ diseases is the appearance of neuronal inclusions that are formed by aggregation of the polyQ proteins with other cellular proteins 5,6 . This has led to the "toxic gain-of-function" hypothesis that essential proteins can be sequestered, which 3 over time leads to cellular dysgenesis. The expression of polyQ can cause other metastable proteins to lose functionality, and in turn these proteins amplify the toxicity of polyQ by enhancing overall aggregation 7 . Self-aggregation of polyQ proteins has been proposed to be mediated by association of parallel β-sheet structures 8 . However, the intrinsic in vivo events leading to the aggregation of polyQ proteins remain poorly understood.Protein misfolding is a natural consequence of protein biogenesis. To combat cytotoxicity that results from the accumulation of misfolded proteins, all cells express molecular chaperones that are essential for the productive folding of proteins 9,10 . Molecular chaperones are of several classes; for example, Hsp70/J-domain proteins interact with unfolded or partially folded proteins in concert with co-chaperones, while the chaperone machines of the chaperonin (Hsp60) family form cage-like structures that sequester non-native states of proteins 11 . The chaperonin containing t-complex polypeptide 1 (CCT)/t-complex polypeptide 1 ring complex (TRiC) is a member of chaperonin family 12 that facilitates the folding of proteins in the eukaryotic cytosol upon ATP hydrolysis 13,14 . CCT shows a weak but significant homology to E. coli GroEL and forms a hexadecamer double-troidal complex composed of eight different subunits 15,16 . Substrate proteins are captured in the cavity, and released after folding is completed 17 . Approximately 10% of newly-synthesized proteins have been proposed to be recognized by CCT.Recently, in a genome-wide screen to identify modifier genes for polyQ aggregation in C. elegans, approximately 200 genes were found to be required for the prevention of polyQ aggregation 18 . This included the genes encoding two Hsp70s, one J-protein, and six CCT subunits. These observations suggested a 4 role of CCT in preventing polyQ aggregation. We show here in mammalian cells that CCT has a key protective role against the toxicity of htt/polyQ and affects aggregation process at the soluble stage. In the context of our recent in vitro data showing that ...

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supporting

confidence: 55%

Cytosolic chaperonin prevents polyglutamine toxicity with altering the aggregation state

et al. 2006

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“…It has been postulated that the eight different CCT subunits of TRiC are needed to recognize a variety of substrates (Feldman et al 2003;Llorca et al 2001). The CCT subunits may recognize different types of proteins, e.g., CCT2 may recognize beta-propeller proteins, while CCT8 may recognize hydrophobic beta sheets.…”

Section: Discussionmentioning

confidence: 99%

“…The most common preparation of TRiC for biomedical research is endogenous TRiC from bovine testes tissue (Feldman et al 2003;Ferreyra and Frydman 2000;Frydman et al 1992). Purification of endogenous TRiC from rabbit reticulocytes has also been effective (Frydman et al 1994;Gao et al 1992;Nimmesgern and Hartl 1993;Norcum 1996).…”

Section: Introductionmentioning

confidence: 99%

“…Although only a few substrates have been studied, it is clear that not all CCT subunits are involved in binding of non-native-state substrates to TRiC (Feldman et al 2003;Hynes and Willison 2000;Llorca et al 2001;. The apical domains of CCT1 and CCT4 have been implicated in TRiC binding to exon one of the huntingtin protein (Tam et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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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

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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.

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“…Stable interactions between an unfolded polypeptide and TRiC seem to result from a set of multivalent, weak interactions between defined motifs in the substrate and individual chaperonin subunits [25,31,32]. Thus, it is possible that the sequence divergence of TRiC subunits expands the range of possible motifs that are accepted in substrates beyond the simple hydrophobic sites offered in group I chaperonins.…”

Section: Tric-substrate Interactionsmentioning

confidence: 99%

Mechanism of the eukaryotic chaperonin: protein folding in the chamber of secrets

Spiess

Meyer

Reißmann

et al. 2004

Trends in Cell Biology

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342

327

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Chaperonins are key components of the cellular chaperone machinery. These large, cylindrical complexes contain a central cavity that binds to unfolded polypeptides and sequesters them from the cellular environment. Substrate folding then occurs in this central cavity in an ATP-dependent manner. The eukaryotic chaperonin TCP-1 ring complex (TRiC, also called CCT) is indispensable for cell survival because the folding of an essential subset of cytosolic proteins requires TRiC, and this function cannot be substituted by other chaperones. This specificity indicates that TRiC has evolved structural and mechanistic features that distinguish it from other chaperones. Although knowledge of this unique complex is in its infancy, we review recent advances that open the way to understanding the secrets of its folding chamber.Protein misfolding has been implicated in several human diseases that have both systemic and neurological implications, including 'conformational diseases' such as Huntington's and Parkinson's that are characterized by the accumulation of toxic protein aggregates [1]. Although small proteins with simple chain topologies can fold spontaneously, the vast majority of cellular proteins is unable to reach its native state without the assistance of elaborate cellular machinery composed of proteins known as molecular chaperones (for review, see Refs [1-4]). A complete understanding of chaperone-assisted protein folding in the cell would be an intellectual tour de force that might, eventually, lead to effective treatments for these diseases.In the cell, protein folding faces additional challenges compared with the refolding of proteins in solution [1,2,4]. For example, in vivo, the linear polypeptide chain emerges vectorially into the cytosol during synthesis on ribosomes. Because the information for the native state is encoded by the entire amino acid sequence, the nascent polypeptide chain is unable to fold stably until fully synthesized, but it exposes hydrophobic sequences into the crowded cellular milieu [4]. Details of how newly translated proteins navigate toward a final, fully functional, folded structure in vivo are not entirely understood, but it is clear that exposed hydrophobic surfaces can contribute to misfolding and aggregation. Accordingly, all cellular compartments contain many structurally and functionally distinct classes of chaperones that vary in size and complexity, ranging from those that bind only to misfolded polypeptides and prevent their aggregation to those that recognize specific classes of proteins and facilitate their folding to the native state in an energy-dependent manner [1][2][3]. In cells, these different classes of chaperones work together to form elaborate, cooperative networks that ensure the correct folding of newly translated proteins; they also ensure that potentially damaging misfolded polypeptides are cleared from the cell [5].

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Tumorigenic Mutations in VHL Disrupt Folding In Vivo by Interfering with Chaperonin Binding

Cited by 100 publications

References 37 publications

Cytosolic chaperonin prevents polyglutamine toxicity with altering the aggregation state

Cytosolic chaperonin prevents polyglutamine toxicity with altering the aggregation state

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

Mechanism of the eukaryotic chaperonin: protein folding in the chamber of secrets

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