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University of Washington Seattle, Seattle, Washington, United States
Nature Genetics (Impact Factor: 29.35). 06/2005; 37(5):526-31. DOI: 10.1038/ng1542
Source: PubMed


Huntington disease is a fatal neurodegenerative disorder caused by expansion of a polyglutamine tract in the protein huntingtin (Htt), which leads to its aggregation in nuclear and cytoplasmic inclusion bodies. We recently identified 52 loss-of-function mutations in yeast genes that enhance the toxicity of a mutant Htt fragment. Here we report the results from a genome-wide loss-of-function suppressor screen in which we identified 28 gene deletions that suppress toxicity of a mutant Htt fragment. The suppressors are known or predicted to have roles in vesicle transport, vacuolar degradation, transcription and prion-like aggregation. Among the most potent suppressors was Bna4 (kynurenine 3-monooxygenase), an enzyme in the kynurenine pathway of tryptophan degradation that has been linked directly to the pathophysiology of Huntington disease in humans by a mechanism that may involve reactive oxygen species. This finding is suggestive of a conserved mechanism of polyglutamine toxicity from yeast to humans and identifies new candidate therapeutic targets for the treatment of Huntington disease.

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Available from: Paul J Muchowski, Oct 01, 2015
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    • "Although the human proteins involved in these diseases have no functional homolog in yeast, upon expression in this organism they form amyloid fibers that can even, at least in some cases and/or situations, be toxic for yeast cells, thereby mimicking the situation observed in human neuronal cells. A nice example of this approach was given by the creation of a yeast model for Huntington disease [30], a familial fatal neurodegenerative disorder caused by the expansion of a polyglutamine tract in the Huntingtin protein (Htt). A mutant form of the first exon of Htt containing the expanded polyglutamine domain (103Q instead of 25Q in the wild type allele) was expressed in budding yeast. "
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    ABSTRACT: Cross-complementation studies offer the possibility to overcome limitations imposed by the inherent complexity of multicellular organisms in the study of human diseases, by taking advantage of simpler model organisms like the budding yeast Saccharomyces cerevisiae. This review deals with, (1) the use of S. cerevisiae as a model organism to study human diseases, (2) yeast-based screening systems for the detection of diseases modifiers, (3) Hailey-Hailey as an example of a calcium-related disease, and (4) the presentation of a yeast-based model to search for chemical modifiers of Hailey-Hailey disease. The preliminary experimental data presented and discussed here show that it is possible to use yeast as a model system for Hailey-Hailey disease and suggest that in all likelihood, yeast has the potential to reveal candidate drugs for the treatment of this disorder. This article is part of a Special Issue entitled: Calcium Signaling In Health and Disease.
    Biochimica et Biophysica Acta 02/2014; 1843(10). DOI:10.1016/j.bbamcr.2014.02.011 · 4.66 Impact Factor
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    • "This forms the basis for an original immune-based therapeutic strategy to selectively target EBV-infected cells, including EBV-carrying tumor cells. The versatile genetic flexibility of the budding yeast Saccharomyces cerevisiae and the high degree of conservation between yeast and mammalian cellular processes have made S. cerevisiae an invaluable tool for modeling human diseases (Bach et al., 2003; Bach et al., 2006; Bilsland et al., 2013; Blondel, 2012; Couplan et al., 2011; Mager and Winderickx, 2005; Perocchi et al., 2008), as well as for identifying and characterizing cellular pathways involved in these disorders and thereby new therapeutic targets (Giorgini et al., 2005; Louie et al., 2012). "
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    ABSTRACT: Epstein-Barr virus (EBV) is tightly associated to certain human cancers but there is of today no specific treatment against EBV-related diseases. The EBV-encoded EBNA1 protein is essential to maintain viral episomes and for viral persistence. EBNA1 is expressed in all EBV infected cells and is highly antigenic. All infected individuals, including cancer patients, have CD8(+) T cells directed towards EBNA1 epitopes, yet the immune system fails to detect and destroy cells harboring the virus. EBV's immune evasion depends on the capacity of the Gly-Ala repeat (GAr) domain of EBNA1 to inhibit the translation of its own mRNA in cis, thereby limiting the production of EBNA1-derived antigenic peptides presented by the Major Histocompatibility Complex (MHC) class I pathway. Here we establish a yeast-based assay for monitoring GAr-dependent inhibition of translation. Using this assay we identify doxorubicin (DXR) as a compound that specifically interferes with the GAr effect on translation in yeast. DXR targets the topoisomerase II/DNA complexes and thereby causes genomic damage. We show, however, that the genotoxic effect of DXR and various analogues thereof is uncoupled from the effect on GAr-mediated translation control. This is further supported by the observation that etoposide and teniposide, representing another class of topoisomerase II/DNA targeting drugs, have no effect on GAr-mediated translation control. DXR and active analogues stimulate in a GAr-dependent manner EBNA1 expression in mammalian cells and overcome GAr-dependent restriction of MHC class I antigen presentation. These results validate our approach as an effective high-throughput screening assay to identify drugs that interfere with EBV immune evasion and, thus, constitute candidates for treating EBV-related diseases, in particular EBV-associated cancers.
    Disease Models and Mechanisms 02/2014; 7(4). DOI:10.1242/dmm.014308 · 4.97 Impact Factor
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    • "3-HK, the product of KMO catalysis, exhibits toxicity to cells through reactive oxygen species generation, the cross-linking of proteins and mitochondrial respiratory chain inhibition [10]. KMO has recently been implicated as a therapeutic target for both Huntington's disease [11] and post-traumatic sepsis [4]. "
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    ABSTRACT: Kynurenine 3-monooxygenase (KMO) is an enzyme central to the kynurenine pathway of tryptophan metabolism. KMO has been implicated as a therapeutic target in several disease states, including Huntington's disease. Recombinant human KMO protein production is challenging due to the presence of transmembrane domains, which localise KMO to the outer mitochondrial membrane and render KMO insoluble in many in vitro expression systems. Efficient bacterial expression of human KMO would accelerate drug development of KMO inhibitors but until now this has not been achieved. Here we report the first successful bacterial (Escherichia coli) expression of active FLAG™-tagged human KMO enzyme expressed in the soluble fraction and progress towards its purification.
    Protein Expression and Purification 12/2013; 95(100). DOI:10.1016/j.pep.2013.11.015 · 1.70 Impact Factor
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