Amino Acid Sequence Requirements of Peptides That Inhibit Polyglutamine-Protein Aggregation and Cell Death

Ren, Hongzu; Nagai, Yoshitaka; Tucker, Timothy J.; Strittmatter, Warren J.; Burke, James R.

doi:10.1006/bbrc.2001.5783

Cited by 35 publications

(36 citation statements)

References 25 publications

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“…This is consistent with our recent observation that QBP1 inhibits the conformational transition of the poly(Q) protein monomer, which occurs before aggregate formation (27). In addition, we previously showed that QBP1 cannot reverse the preformed poly(Q) aggregates in vitro (28), further supporting that QBP1 targets monomers and small oligomers of the poly(Q) protein. Evaluation of the ratio of the slow diffusion component fraction (F 2 ) revealed that the time-dependent increase in the F 2 ratio of (Q) 45 -GFP was significantly suppressed by co-expression of QBP1, indicating inhibition of large aggregate formation of the poly(Q) protein (Fig.…”

Section: ϫ3supporting

confidence: 92%

Detection of Polyglutamine Protein Oligomers in Cells by Fluorescence Correlation Spectroscopy

Takahashi

Okamoto

Popiel

et al. 2007

Journal of Biological Chemistry

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Abnormal aggregation of misfolded proteins and their deposition as inclusion bodies in the brain have been implicated as a common molecular pathogenesis of neurodegenerative diseases including Alzheimer, Parkinson, and the polyglutamine (poly(Q)) diseases, which are collectively called the conformational diseases. The poly(Q) diseases, including Huntington disease and various types of spinocerebellar ataxia, are caused by abnormal expansions of the poly(Q) stretch within diseasecausing proteins, which triggers the disease-causing proteins to aggregate into insoluble ␤-sheet-rich amyloid fibrils. Although oligomeric structures formed in vitro are believed to be more toxic than mature amyloid fibrils in these diseases, the existence of oligomers in vivo has remained controversial. To explore oligomer formation in cells, we employed fluorescence correlation spectroscopy (FCS), which is a highly sensitive technique for investigating the dynamics of fluorescent molecules in solution. Here we demonstrate direct evidence for oligomer formation of poly(Q)-green fluorescent protein (GFP) fusion proteins expressed in cultured cells, by showing a time-dependent increase in their diffusion time and particle size by FCS. We show that the poly(Q)-binding peptide QBP1 inhibits poly(Q)-GFP oligomer formation, whereas Congo red only inhibits the growth of oligomers, but not the initial formation of the poly(Q)-GFP oligomers, suggesting that FCS is capable of identifying poly(Q) oligomer inhibitors. We therefore conclude that FCS is a useful technique to monitor the oligomerization of disease-causing proteins in cells as well as its inhibition in the conformational diseases.Abnormal aggregation and deposition of misfolded proteins in the brain have been implicated as a common molecular pathogenesis of neurodegenerative diseases including Alzheimer disease, Parkinson disease, and the polyglutamine (poly(Q)) 2 diseases, which are collectively called the conformational diseases (1-3). The poly(Q) diseases are a group of at least nine inherited neurodegenerative diseases including Huntington disease and various types of spinocerebellar ataxia, which are caused by abnormal expansions of the poly(Q) stretch to above 40 glutamines within each unrelated diseasecausing protein (4, 5). In the pathogenesis of the poly(Q) diseases, expansions of the poly(Q) stretch in disease-causing proteins are believed to cause alterations in the protein conformation, resulting in assembly of the proteins into insoluble ␤-sheet-rich amyloid-like fibrillar aggregates, and eventually their deposition as inclusion bodies inside affected neurons. However, Finkbeiner and colleagues (6) demonstrated that neuronal cells with poly(Q) protein inclusions have a decreased risk of death, suggesting that the diffuse poly(Q) protein rather than inclusion bodies causes cytotoxicity. Inclusion bodies, which are large intracellular deposits of aggregated proteins, are believed to be formed as a cytoprotective response against the overproduction of misfolded/aggregated pro...

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Section: ϫ3supporting

confidence: 92%

Detection of Polyglutamine Protein Oligomers in Cells by Fluorescence Correlation Spectroscopy

Takahashi

Okamoto

Popiel

et al. 2007

Journal of Biological Chemistry

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“…The control peptide SCR had no effect on thio-Q62 aggregation. Furthermore, addition of QBP1 after the initiation of thio-Q62 aggregation inhibited any further aggregation, but could not solubilize the aggregates that were already formed, confirming that QBP1 inhibits the earlier stages of the polyQ aggregation process [28]. We also found that (QBP1) 2 , a tandem repeat of QBP1 (see Table 1) with a higher binding affinity to the expanded polyQ stretch (Kd 0.6 μM), presumably due to the additional polyQ binding sequence, exhibits stronger polyQ aggregation inhibitory activity [26].…”

Section: Qbp1 Inhibits the Toxic Conformational Transition And Aggregmentioning

confidence: 98%

“…Towards this goal we have identified the minimal active sequence of QBP1 (WKWWPGIF) [28], as well as its pharmacophores [41,42]. We are currently working towards elucidating the structure of QBP1 when bound to the expanded polyQ stretch, which should further aid in the design of small chemical analogues of QBP1.…”

Section: Therapeutic Effects Of Qbp1 By Exogenous Deliverymentioning

confidence: 99%

Inhibition of Protein Misfolding/Aggregation Using Polyglutamine Binding Peptide QBP1 as a Therapy for the Polyglutamine Diseases

et al. 2013

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Protein misfolding and aggregation in the brain have been recognized to be crucial in the pathogenesis of various neurodegenerative diseases, including Alzheimer's, Parkinson's, and the polyglutamine (polyQ) diseases, which are collectively called the "protein misfolding diseases". In the polyQ diseases, an abnormally expanded polyQ stretch in the responsible proteins causes the proteins to misfold and aggregate, eventually resulting in neurodegeneration. Hypothesizing that polyQ protein misfolding and aggregation could be inhibited by molecules specifically binding to the expanded polyQ stretch, we identified polyQ binding peptide 1 (QBP1). We show that QBP1 does, indeed, inhibit misfolding and aggregation of the expanded polyQ protein in vitro. Furthermore overexpression of QBP1 by the crossing of transgenic animals inhibits neurodegeneration in Drosophila models of the polyQ diseases. We also introduce our attempts to deliver QBP1 into the brain by administration using viral vectors and protein transduction domains. Interestingly, recent data suggest that QBP1 can also inhibit the misfolding/aggregation of proteins responsible for other protein misfolding diseases, highlighting the potential of QBP1 as a general therapeutic molecule for a wide range of neurodegenerative diseases. We hope that in the near future, aggregation inhibitor-based drugs will be developed and bring relief to patients suffering from these currently intractable protein misfolding diseases.

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“…A spacer residue was required (most often Pro), and then either GIF or another repeat of WKWW. It has been suggested (44) that the WKWW motif binds to the polyQ domain in a rare aggregation-prone conformation and that the adjacent Pro interferes with ␤-sheet formation. QBP1 inhibits early steps in Fig.…”

Section: Comparison Of Different Polyq Hairpin Turn Conformationsmentioning

confidence: 99%

Characterization of a possible amyloidogenic precursor in glutamine-repeat neurodegenerative diseases

Armen

Bernard

Day

et al. 2005

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

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Several neurodegenerative diseases are linked to expanded repeats of glutamine residues, which lead to the formation of amyloid fibrils and neuronal death. The length of the repeats correlates with the onset of Huntington's disease, such that healthy individuals have <38 residues and individuals with >38 repeats exhibit symptoms. Because it is difficult to obtain atomicresolution structural information for poly(L-glutamine) (polyQ) in aqueous solution experimentally, we performed molecular dynamics simulations to investigate the conformational behavior of this homopolymer. In simulations of 20-, 40-, and 80-mer polyQ, we observed the formation of the ''␣-extended chain'' conformation, which is characterized by alternating residues in the ␣L and ␣R conformations to yield a sheet. The structural transition from disordered random-coil conformations to the ␣-extended chain conformation exhibits modest length and temperature dependence, in agreement with the experimental observation that aggregation depends on length and temperature. We propose that fibril formation in polyQ may occur through an ␣-sheet structure ␣-sheet ͉ amyloidosis ͉ misfolding disease ͉ molecular dynamics ͉ poly(L-glutamine)

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Amino Acid Sequence Requirements of Peptides That Inhibit Polyglutamine-Protein Aggregation and Cell Death

Cited by 35 publications

References 25 publications

Detection of Polyglutamine Protein Oligomers in Cells by Fluorescence Correlation Spectroscopy

Detection of Polyglutamine Protein Oligomers in Cells by Fluorescence Correlation Spectroscopy

Inhibition of Protein Misfolding/Aggregation Using Polyglutamine Binding Peptide QBP1 as a Therapy for the Polyglutamine Diseases

Characterization of a possible amyloidogenic precursor in glutamine-repeat neurodegenerative diseases

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