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Koning Shen, Barbara Calamini, Jonathan A Fauerbach, Boxue Ma, Sarah H Shahmoradian, Ivana L Serrano Lachapel, Wah Chiu, Donald C Lo, Judith Frydman
Many neurodegenerative diseases are linked to amyloid aggregation. In Huntington's disease (HD), neurotoxicity correlates with increased aggregation propensity of a polyglutamine (polyQ) expansion in exon 1 of mutant huntingtin protein (mHtt). Here we establish how the domains flanking the polyQ tract shape the mHtt conformational landscape in vitro and in neurons. In vitro, the flanking domains have opposing effects on the conformation and stabilities of oligomers and amyloid fibrils. The N-terminal N17 promotes amyloid fibril formation, while the C-terminal Proline Rich Domain destabilizes fibrils and enhances oligomer formation...
October 18, 2016: ELife
Alessandra Ruggieri, Simona Saredi, Simona Zanotti, Maria Barbara Pasanisi, Lorenzo Maggi, Marina Mora
Mutations in the DNAJB6 gene have been associated with the autosomal dominant limb girdle muscular dystrophy type 1D (LGMD1D), a disorder characterized by abnormal protein aggregates and rimmed vacuoles in muscle fibers. DNAJB6 is a ubiquitously expressed Hsp40 co-chaperone characterized by a J domain that specifies Hsp70 functions in the cellular environment. DNAJB6 is also a potent inhibitor of expanded polyglutamine (polyQ) aggregation preventing aggregate toxicity in cells. In DNAJB6-mutated patients this anti-aggregation property is significantly reduced, albeit not completely lost...
2016: Frontiers in Molecular Biosciences
Yuwei Jiang, Sonja E DiGregorio, Martin L Duennwald, Patrick Lajoie
The palette of fluorescent proteins (FPs) available for live-cell imaging contains proteins that strongly differ in their biophysical properties. FPs cannot be assumed to be equivalent and in certain cases could significantly perturb the behavior of fluorescent reporters. We employed Saccharomyces cerevisiae to comprehensively study the impact of FPs on the toxicity of polyglutamine (polyQ) expansion proteins associated with Huntington's disease. The toxicity of polyQ fusion constructs is highly dependent on the sequences flanking the polyQ repeats...
October 13, 2016: Traffic
Wen Xi, Xin Wang, Thomas M Laue, Clyde L Denis
Huntington's disease (HD) results from expansions of polyglutamine stretches (polyQ) in the huntingtin protein (Htt) that promote protein aggregation, neurodegeneration, and death. Since the diversity and sizes of the soluble Htt-polyQ aggregates that have been linked to cytotoxicity are unknown, we investigated soluble Htt-polyQ aggregates using analytical ultracentrifugation. Soon after induction in a yeast HD model system, non-toxic Htt-25Q and cytotoxic Htt-103Q both formed soluble aggregates 29S to 200S in size...
October 10, 2016: Scientific Reports
Sara Sameni, Adeela Syed, J Lawrence Marsh, Michelle A Digman
Huntington disease (HD) is an autosomal neurodegenerative disorder caused by the expansion of Polyglutamine (polyQ) in exon 1 of the Huntingtin protein. Glutamine repeats below 36 are considered normal while repeats above 40 lead to HD. Impairment in energy metabolism is a common trend in Huntington pathogenesis; however, this effect is not fully understood. Here, we used the phasor approach and Fluorescence Lifetime Imaging Microscopy (FLIM) to measure changes between free and bound fractions of NADH as a indirect measure of metabolic alteration in living cells...
October 7, 2016: Scientific Reports
Limin Hao, Oshrit Ben-David, Suzann M Babb, Anthony H Futerman, Bruce M Cohen, Edgar A Buttner
Defining the mechanisms of action of the anti-psychotic drug (APD), clozapine is of great importance, as clozapine is more effective and has therapeutic benefits in a broader range of psychiatric disorders than other APDs. Its range of actions have not been fully characterized. Exposure to APDs early in development causes dose-dependent developmental delay and lethality in C. elegans. A previous genome-wide RNAi screen for suppressors of clozapine-induced developmental delay and lethality revealed 40 candidate genes, including sms-1, which encodes a sphingomyelin synthase...
October 6, 2016: Neuropsychopharmacology: Official Publication of the American College of Neuropsychopharmacology
Gwen E Owens, Danielle M New, Alejandra I Olvera, Julia Ashlyn Manzella, Brittney L Macon, Joshua C Dunn, David A Cooper, Robyn L Rouleau, Daniel S Connor, Pamela J Bjorkman
Huntington's disease is one of nine neurodegenerative diseases caused by a polyglutamine (polyQ)-repeat expansion. An anti-polyQ antigen-binding fragment, MW1 Fab, was crystallized both on Earth and on the International Space Station, a microgravity environment where convection is limited. Once the crystals returned to Earth, the number, size and morphology of all crystals were recorded, and X-ray data were collected from representative crystals. The results generally agreed with previous microgravity crystallization studies...
October 1, 2016: Acta Crystallographica. Section F, Structural Biology Communications
Kodai Machida, Tomoaki Shigeta, Ayano Kobayashi, Ai Masumoto, Yuna Hidaka, Hiroaki Imataka
Protein misfolding and aggregation is one of the major causes of neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and Huntington's disease. So far protein aggregation related to these diseases has been studied using animals, cultured cells or purified proteins. In this study, we show that a newly synthesized polyglutamine protein implicated in Huntington's disease forms large aggregates in HeLa cells, and successfully recapitulate the process of this aggregation using a translation-based system derived from HeLa cell extracts...
October 1, 2016: Journal of Biotechnology
Chang Heng Hsieh, Li-Ching Lee, Wai-Yin Leong, Tsai-Chen Yang, Ching-Fa Yao, Kang Fang
Trinucleotide CAG repeat expansion in the coding region of genes has a propensity to form polyglutamine (polyQ) aggregates that contribute to neuronal disorders. Strategies in elevating autophagy to disintegrate the insoluble aggregates without injuring cells have become a major goal for therapy. In this work, a triazole derivative, OC-13, was found accelerating autophagic clearance of polyQ aggregation in human neuroblastoma cells following induction of the enhanced green fluorescence-conjugated chimeric protein that enclosed 79 polyQ repeats (Q79-EGFP)...
2016: Drug Design, Development and Therapy
Lili Guo, Wil Prall, Xiaolu Yang
Protein misfolding and aggregation are associated with various neurodegenerative diseases. Cellular mechanisms that recognize and degrade misfolded proteins may serve as potential therapeutic targets. To distinguish degradation of misfolding-prone proteins from other mechanisms that regulate their levels, one important method is to measure protein half-life in cells. However, this can be challenging because misfolding-prone proteins may exist in different forms, including the native form and misfolded forms of distinct characteristics...
2016: Journal of Visualized Experiments: JoVE
Elisa Giorgetti, Zhigang Yu, Jason P Chua, Ryosuke Shimamura, Lili Zhao, Fan Zhu, Sriram Venneti, Maria Pennuto, Yuanfang Guan, Gene Hung, Andrew P Lieberman
Spinal and bulbar muscular atrophy (SBMA), a progressive degenerative disorder, is caused by a CAG/glutamine expansion in the androgen receptor (polyQ AR). Recent studies demonstrate that skeletal muscle is an important site of toxicity that contributes to the SBMA phenotype. Here, we sought to identify critical pathways altered in muscle that underlie disease manifestations in AR113Q mice. This led to the unanticipated identification of gene expression changes affecting regulators of carbohydrate metabolism, similar to those triggered by denervation...
September 27, 2016: Cell Reports
Ashley A Zurawel, Ruth Kabeche, Sonja E DiGregorio, Lin Deng, Kartikeya M Menon, Hannah Opalko, Martin L Duennwald, James B Moseley, Surachai Supattapone
: Proteins containing polyglutamine (polyQ) regions are found in almost all eukaryotes, albeit with various frequencies. In humans, proteins such as huntingtin (Htt) with abnormally expanded polyQ regions cause neurodegenerative diseases such as Huntington's disease (HD). To study how the presence of endogenous polyQ aggregation modulates polyQ aggregation and toxicity, we expressed polyQ expanded Htt fragments (polyQ Htt) in Schizosaccharomyces pombe In stark contrast to other unicellular fungi, such as Saccharomyces cerevisiae, S...
September 27, 2016: MBio
Ana Rosa Vieira Melo, Amanda Ramos, Nadiya Kazachkova, Mafalda Raposo, Bruno Filipe Bettencourt, Ana Rita Rendeiro, Teresa Kay, João Vasconcelos, Jácome Bruges-Armas, Manuela Lima
INTRODUCTION AND OBJECTIVE: Spinocerebellar ataxia type 3 (SCA3) is a polyglutamine (polyQ) disorder for which the routine molecular testing is based on PCR and automated capillary electrophoresis. When only a normal allele is detected by standard PCR, the hypothesis of a failed amplification of the expanded allele must be raised. In such cases, complementary techniques such as Southern Blot or triplet repeat primed PCR (TP-PCR) have to be applied. For SCA3, TP-PCR is implemented in some diagnostic laboratories, but a tested protocol has yet to be published...
September 20, 2016: Molecular Diagnosis & Therapy
Tanut Kunkanjanawan, Richard L Carter, Melinda S Prucha, Jinjing Yang, Rangsun Parnpai, Anthony W S Chan
Huntington's disease (HD) is an inherited neurodegenerative disorder caused by the expansion of polyglutamine (polyQ) tract that leads to motor, cognitive and psychiatric impairment. Currently there is no cure for HD. A transgenic HD nonhuman primate (HD-NHP) model was developed with progressive development of clinical and pathological features similar to human HD, which suggested the potential preclinical application of the HD-NHP model. Elevated expression of miR-196a was observed in both HD-NHP and human HD brains...
2016: PloS One
Yujin E Kim, Fabian Hosp, Frédéric Frottin, Hui Ge, Matthias Mann, Manajit Hayer-Hartl, F Ulrich Hartl
Huntington's disease is one of several neurodegenerative disorders characterized by the aggregation of polyglutamine (polyQ)-expanded mutant protein. How polyQ aggregation leads to cellular dysfunction is not well understood. Here, we analyzed aberrant protein interactions of soluble oligomers and insoluble inclusions of mutant huntingtin using in-cell single molecule fluorescence spectroscopy and quantitative proteomics. We find that the interactome of soluble oligomers is highly complex, with an enrichment of RNA-binding proteins as well as proteins functioning in ribosome biogenesis, translation, transcription, and vesicle transport...
September 15, 2016: Molecular Cell
Maximilian O Press, Amy Lanctot, Christine Queitsch
Plants have evolved elaborate mechanisms controlling developmental responses to environmental stimuli. A particularly important stimulus is temperature. Previous work has identified the interplay of PIF4 and ELF3 as a central circuit underlying thermal responses in Arabidopsis thaliana. However, thermal responses vary widely among strains, possibly offering mechanistic insights into the wiring of this circuit. ELF3 contains a polyglutamine (polyQ) tract that is crucial for ELF3 function and varies in length across strains...
2016: PloS One
Pinaki Misra, Ravindra Kodali, Saketh Chemuru, Karunakar Kar, Ronald Wetzel
Since early oligomeric intermediates in amyloid assembly are often transient and difficult to distinguish, characterize and quantify, the mechanistic basis of the initiation of spontaneous amyloid growth is often opaque. We describe here an approach to the analysis of the Aβ aggregation mechanism that uses Aβ-polyglutamine hybrid peptides designed to retard amyloid maturation and an adjusted thioflavin intensity scale that reveals structural features of aggregation intermediates. The results support an aggregation initiation mechanism for Aβ-polyQ hybrids, and by extension for full-length Aβ peptides, in which a modular Aβ C-terminal segment mediates rapid, non-nucleated formation of α-helical oligomers...
2016: Nature Communications
Marta Fernández-Nogales, María Santos-Galindo, Ivó H Hernández, Jorge R Cabrera, José J Lucas
Huntington's disease (HD) is caused by a CAG-repeat encoding a polyglutamine (polyQ) tract in the huntingtin protein. There is plenty of evidence of polyQ-driven toxicity. However, CAG repeat RNA-driven alteration of splicing has recently been proposed in analogy to CUG-repeat diseases. Here we review the reported alteration of the CAG-repeat associated splicing factor SRSF6 in brains of HD patients and mouse models and how this correlates with altered splicing of, at least, two microtubule-associated proteins in HD, namely MAPT (tau) and MAP2...
August 16, 2016: Brain Pathology
Eulàlia Martí
Huntington's disease (HD) belongs to the group of inherited polyglutamine (PolyQ) diseases caused by an expanded CAG repeat in the coding region of the Huntingtin (HTT) gene that results in an elongated polyQ stretch. Abnormal function and aggregation of the mutant protein has been typically delineated as the main molecular cause underlying disease development. However, the most recent advances have revealed novel pathogenic pathways directly dependent on an RNA toxic gain-of-function. Expanded CAG repeats within exon 1 of the HTT mRNA induce toxicity through mechanisms involving, at least in part, gene expression perturbations...
August 16, 2016: Brain Pathology
Ian H Kratter, Hengameh Zahed, Alice Lau, Andrey S Tsvetkov, Aaron C Daub, Kurt F Weiberth, Xiaofeng Gu, Frédéric Saudou, Sandrine Humbert, X William Yang, Alex Osmand, Joan S Steffan, Eliezer Masliah, Steven Finkbeiner
Huntington's disease (HD) is a progressive, adult-onset neurodegenerative disease caused by a polyglutamine (polyQ) expansion in the N-terminal region of the protein huntingtin (HTT). There are no cures or disease-modifying therapies for HD. HTT has a highly conserved Akt phosphorylation site at serine 421, and prior work in HD models found that phosphorylation at S421 (S421-P) diminishes the toxicity of mutant HTT (mHTT) fragments in neuronal cultures. However, whether S421-P affects the toxicity of mHTT in vivo remains unknown...
September 1, 2016: Journal of Clinical Investigation
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