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https://www.readbyqxmd.com/read/28531354/monomeric-polyglutamine-structures-that-evolve-into-fibrils
#1
David Punihaole, Ryan S Jakubek, Riley James Workman, Lauren E Marbella, Patricia Campbell, Jeffry D Madura, Sanford A Asher
We investigate the solution and fibril conformations and structural transitions of the polyglutamine (polyQ) peptide, D2Q10K2 (Q10), by synergistically using UV Resonance Raman (UVRR) spectroscopy and Molecular Dynamics (MD) simulations. We show that Q10 adopts two distinct, monomeric solution conformational states, a collapsed β-strand and a PPII-like structure that do not readily interconvert. This clearly indicates a high activation barrier in solution that prevents equilibration between these structures...
May 22, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28527524/c9orf72-hexanucleotide-repeat-expansions-and-ataxin-2-intermediate-length-repeat-expansions-in-indian-patients-with-amyotrophic-lateral-sclerosis
#2
Priyam Narain, James Gomes, Rohit Bhatia, Inder Singh, Perumal Vivekanandan
Repeat expansions in the chromosome 9 open reading frame 72 (C9orf72) gene have been recognized as a major contributor to amyotrophic lateral sclerosis (ALS) and frontotemporal dementia in the Caucasian population. Intermediate length repeat expansions of CAG (polyQ) repeat in the ATXN2 gene have also been reported to increase the risk of developing ALS in North America and Europe. We screened 131 ALS patients and 127 healthy controls from India for C9orf72 and ATXN2 repeat expansions. We found pathogenic hexanucleotide expansions in 3 of the 127 sporadic ALS patients, in 1 of the 4 familial ALS patients, and in none of the healthy controls...
April 26, 2017: Neurobiology of Aging
https://www.readbyqxmd.com/read/28525545/gene-co-expression-network-analysis-for-identifying-modules-and-functionally-enriched-pathways-in-sca2
#3
Lance T Pflieger, Warunee Dansithong, Sharan Paul, Daniel Scoles, Karla P Figueroa, Pratap Meera, Thomas S Otis, Julio C Facelli, Stefan M Pulst
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disease caused by CAG repeat expansion in the ATXN2 gene. The repeat resides in an encoded region of the gene resulting in polyglutamine (polyQ) expansion which has been assumed to result in gain of function, predominantly, for the ATXN2 protein. We evaluated temporal cerebellar expression profiles by RNA sequencing of ATXN2Q127 mice vs wildtype littermates. ATXN2Q127 mice are characterized by a progressive motor phenotype onset, and have progressive cerebellar molecular and neurophysiological (Purkinje cell firing frequency) phenotypes...
May 19, 2017: Human Molecular Genetics
https://www.readbyqxmd.com/read/28524599/modulation-of-nuclear-rest-by-alternative-splicing-a-potential-therapeutic-target-for-huntington-s-disease
#4
Guo-Lin Chen, Qi Ma, Dharmendra Goswami, Jianyu Shang, Gregory M Miller
Huntington's disease (HD) is caused by a genetically mutated huntingtin (mHtt) protein with expanded polyQ stretch, which impairs cytosolic sequestration of the repressor element-1 silencing transcription factor (REST), resulting in excessive nuclear REST and subsequent repression of neuronal genes. We recently demonstrated that REST undergoes extensive, context-dependent alternative splicing, of which exon-3 skipping (∆E3 )-a common event in human and nonhuman primates-causes loss of a motif critical for REST nuclear targeting...
May 19, 2017: Journal of Cellular and Molecular Medicine
https://www.readbyqxmd.com/read/28511915/altered-ionic-currents-and-amelioration-by-igf-1-and-pacap-in-motoneuron-derived-cells-modelling-sbma
#5
Aura M Jiménez Garduño, Leon J Juárez-Hernández, María J Polanco, Laura Tosatto, Daniela Michelatti, Daniele Arosio, Manuela Basso, Maria Pennuto, Carlo Musio
Spinal and bulbar muscular atrophy (SBMA), also known as Kennedy's disease, is a motor neuron disease caused by the expansion of a polymorphic CAG tandem repeat encoding a polyglutamine (polyQ) tract in the androgen receptor (AR) gene. SBMA is triggered by the binding of mutant AR to its natural ligands, testosterone and dihydrotestosterone (DHT). To investigate the neuronal alterations of motor neuron cell models of SBMA, we applied patch-clamp methods to verify how polyQ expansions in the AR alter cell ionic currents...
May 10, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28503130/uncoupling-the-trade-off-between-somatic-proteostasis-and-reproduction-in-caenorhabditis-elegans-models-of-polyglutamine-diseases
#6
Netta Shemesh, Nadav Shai, Lana Meshnik, Rotem Katalan, Anat Ben-Zvi
Caenorhabditis elegans somatic protein homeostasis (proteostasis) is actively remodeled at the onset of reproduction. This proteostatic collapse is regulated cell-nonautonomously by signals from the reproductive system that transmit the commitment to reproduction to somatic cells. Here, we asked whether the link between the reproductive system and somatic proteostasis could be uncoupled by activating downstream effectors in the gonadal longevity cascade. Specifically, we examined whether over-expression of lipl-4 (lipl-4(oe)), a target gene of the gonadal longevity pathway, or increase in arachidonic acid (AA) levels, associated with lipl-4(oe), modulated proteostasis and reproduction...
2017: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/28499347/the-dynamics-of-early-state-transcriptional-changes-and-aggregate-formation-in-a-huntington-s-disease-cell-model
#7
Martijn van Hagen, Diewertje G E Piebes, Wim C de Leeuw, Ilona M Vuist, Willeke M C van Roon-Mom, Perry D Moerland, Pernette J Verschure
BACKGROUND: Huntington's disease (HD) is a fatal neurodegenerative disorder caused by a CAG expansion in the Huntingtin (HTT) gene. Proteolytic cleavage of mutant huntingtin (Htt) protein with an expanded polyglutamine (polyQ) stretch results in production of Htt fragments that aggregate and induce impaired ubiquitin proteasome, mitochondrial functioning and transcriptional dysregulation. To understand the time-resolved relationship between aggregate formation and transcriptional changes at early disease stages, we performed temporal transcriptome profiling and quantification of aggregate formation in living cells in an inducible HD cell model...
May 12, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28488702/mechanisms-of-diseases-excessive-polyq-tracts-curb-autophagy
#8
Paulina Strzyz
No abstract text is available yet for this article.
May 10, 2017: Nature Reviews. Molecular Cell Biology
https://www.readbyqxmd.com/read/28473226/kennedy-disease-x-linked-recessive-bulbospinal-neuronopathy-a-comprehensive-review-from-pathophysiology-to-therapy
#9
REVIEW
G Querin, G Sorarù, P-F Pradat
Kennedy's disease, also known as spinal and bulbar muscular atrophy (SBMA), is a rare, adult-onset, X-linked recessive neuromuscular disease caused by expansion of a CAG repeat sequence in exon 1 of the androgen receptor gene (AR) encoding a polyglutamine (polyQ) tract. The polyQ-expanded AR accumulates in nuclei, and initiates degeneration and loss of motor neurons and dorsal root ganglia. While the disease has long been considered a pure lower motor neuron disease, recently, the presence of major hyper-creatine-kinase (CK)-emia and myopathic alterations on muscle biopsy has suggested the presence of a primary myopathy underlying a wide range of clinical manifestations...
May 1, 2017: Revue Neurologique
https://www.readbyqxmd.com/read/28453707/the-role-of-ar-polyq-tract-in-male-breast-carcinoma-lesson-from-an-sbma-case
#10
G Querin, I Martinelli, C Bertolin, E Pegoraro, M Pennuto, G Sorarù
No abstract text is available yet for this article.
May 1, 2017: Annals of Oncology: Official Journal of the European Society for Medical Oncology
https://www.readbyqxmd.com/read/28445460/polyglutamine-tracts-regulate-beclin-1-dependent-autophagy
#11
Avraham Ashkenazi, Carla F Bento, Thomas Ricketts, Mariella Vicinanza, Farah Siddiqi, Mariana Pavel, Ferdinando Squitieri, Maarten C Hardenberg, Sara Imarisio, Fiona M Menzies, David C Rubinsztein
Nine neurodegenerative diseases are caused by expanded polyglutamine (polyQ) tracts in different proteins, such as huntingtin in Huntington's disease and ataxin 3 in spinocerebellar ataxia type 3 (SCA3). Age at onset of disease decreases with increasing polyglutamine length in these proteins and the normal length also varies. PolyQ expansions drive pathogenesis in these diseases, as isolated polyQ tracts are toxic, and an N-terminal huntingtin fragment comprising exon 1, which occurs in vivo as a result of alternative splicing, causes toxicity...
May 4, 2017: Nature
https://www.readbyqxmd.com/read/28408866/post-translational-modifications-and-protein-quality-control-in-motor-neuron-and-polyglutamine-diseases
#12
REVIEW
Fabio Sambataro, Maria Pennuto
Neurodegenerative diseases, including motor neuron and polyglutamine (polyQ) diseases, are a broad class of neurological disorders. These diseases are characterized by neuronal dysfunction and death, and by the accumulation of toxic aggregation-prone proteins in the forms of inclusions and micro-aggregates. Protein quality control is a cellular mechanism to reduce the burden of accumulation of misfolded proteins, a function that results from the coordinated actions of chaperones and degradation systems, such as the ubiquitin-proteasome system (UPS) and autophagy-lysosomal degradation system...
2017: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/28400517/aggregation-landscapes-of-huntingtin-exon-1-protein-fragments-and-the-critical-repeat-length-for-the-onset-of-huntington-s-disease
#13
Mingchen Chen, Peter G Wolynes
Huntington's disease (HD) is a neurodegenerative disease caused by an abnormal expansion in the polyglutamine (polyQ) track of the Huntingtin (HTT) protein. The severity of the disease depends on the polyQ repeat length, arising only in patients with proteins having 36 repeats or more. Previous studies have shown that the aggregation of N-terminal fragments (encoded by HTT exon 1) underlies the disease pathology in mouse models and that the HTT exon 1 gene product can self-assemble into amyloid structures. Here, we provide detailed structural mechanisms for aggregation of several protein fragments encoded by HTT exon 1 by using the associative memory, water-mediated, structure and energy model (AWSEM) to construct their free energy landscapes...
April 25, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28398721/inclusions-of-r6-2-mice-are-not-amyloid-and-differ-structurally-from-those-of-huntington-disease-brain
#14
William André, Christophe Sandt, Isabelle Nondier, Philippe Djian, Guylaine Hoffner
R6/2 mice contain an N-terminal fragment of human huntingtin with an expanded polyQ and develop a neurological disease resembling Huntington disease. Although the brain of R6/2 mice contains numerous inclusions, there is very little neuronal death. In that respect, R6/2 mice differ from patients with Huntington disease whose striatum and cerebral cortex develop inclusions associated with extensive neuronal loss. We have previously demonstrated using synchrotron-based infrared microspectroscopy that the striatum and the cortex of patients with Huntington disease contained inclusions specifically enriched in amyloid β-sheets...
April 24, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28386214/chaperones-in-polyglutamine-aggregation-beyond-the-q-stretch
#15
REVIEW
E F E Kuiper, Eduardo P de Mattos, Laura B Jardim, Harm H Kampinga, Steven Bergink
Expanded polyglutamine (polyQ) stretches in at least nine unrelated proteins lead to inherited neuronal dysfunction and degeneration. The expansion size in all diseases correlates with age at onset (AO) of disease and with polyQ protein aggregation, indicating that the expanded polyQ stretch is the main driving force for the disease onset. Interestingly, there is marked interpatient variability in expansion thresholds for a given disease. Between different polyQ diseases the repeat length vs. AO also indicates the existence of modulatory effects on aggregation of the upstream and downstream amino acid sequences flanking the Q expansion...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28375147/crystal-structures-of-hsp104-n-terminal-domains-from-saccharomyces-cerevisiae-and-candida-albicans-suggest-the-mechanism-for-the-function-of-hsp104-in-dissolving-prions
#16
Peng Wang, Jingzhi Li, Clarissa Weaver, Aaron Lucius, Bingdong Sha
Hsp104 is a yeast member of the Hsp100 family which functions as a molecular chaperone to disaggregate misfolded polypeptides. To understand the mechanism by which the Hsp104 N-terminal domain (NTD) interacts with its peptide substrates, crystal structures of the Hsp104 NTDs from Saccharomyces cerevisiae (ScHsp104NTD) and Candida albicans (CaHsp104NTD) have been determined at high resolution. The structures of ScHsp104NTD and CaHsp104NTD reveal that the yeast Hsp104 NTD may utilize a conserved putative peptide-binding groove to interact with misfolded polypeptides...
April 1, 2017: Acta Crystallographica. Section D, Structural Biology
https://www.readbyqxmd.com/read/28374014/transgenic-monkey-model-of-the-polyglutamine-diseases-recapitulating-progressive-neurological-symptoms
#17
Ikuo Tomioka, Hidetoshi Ishibashi, Eiko N Minakawa, Hideyuki H Motohashi, Osamu Takayama, Yuko Saito, H Akiko Popiel, Sandra Puentes, Kensuke Owari, Terumi Nakatani, Naotake Nogami, Kazuhiro Yamamoto, Satoru Noguchi, Takahiro Yonekawa, Yoko Tanaka, Naoko Fujita, Hikaru Suzuki, Hisae Kikuchi, Shu Aizawa, Seiichi Nagano, Daisuke Yamada, Ichizo Nishino, Noritaka Ichinohe, Keiji Wada, Shinichi Kohsaka, Yoshitaka Nagai, Kazuhiko Seki
Age-associated neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and the polyglutamine (polyQ) diseases, are becoming prevalent as a consequence of elongation of the human lifespan. Although various rodent models have been developed to study and overcome these diseases, they have limitations in their translational research utility owing to differences from humans in brain structure and function and in drug metabolism. Here, we generated a transgenic marmoset model of the polyQ diseases, showing progressive neurological symptoms including motor impairment...
March 2017: ENeuro
https://www.readbyqxmd.com/read/28357370/attenuation-of-polyglutamine-induced-toxicity-by-enhancement-of-mitochondrial-oxphos-in-yeast-and-fly-models-of-aging
#18
Andrea L Ruetenik, Alejandro Ocampo, Kai Ruan, Yi Zhu, Chong Li, R Grace Zhai, Antoni Barrientos
Defects in mitochondrial biogenesis and function are common in many neurodegenerative disorders, including Huntington's disease (HD). We have previously shown that in yeast models of HD, enhancement of mitochondrial biogenesis through overexpression of Hap4, the catalytic subunit of the transcriptional complex that regulates mitochondrial gene expression, alleviates the growth arrest induced by expanded polyglutamine (polyQ) tract peptides in rapidly dividing cells. However, the mechanism through which HAP4 overexpression exerts this protection remains unclear...
July 26, 2016: Microbial Cell
https://www.readbyqxmd.com/read/28339398/n-terminal-fragments-of-huntingtin-longer-than-residue-170-form-visible-aggregates-independently-to-polyglutamine-expansion
#19
Moore Z Chen, Sue-Ann Mok, Angelique R Ormsby, Paul J Muchowski, Danny M Hatters
BACKGROUND: A hallmark of Huntington's disease is the progressive aggregation of full length and N-terminal fragments of polyglutamine (polyQ)-expanded Huntingtin (Htt) into intracellular inclusions. The production of N-terminal fragments appears important for enabling pathology and aggregation; and hence the direct expression of a variety of N-terminal fragments are commonly used to model HD in animal and cellular models. OBJECTIVE: It remains unclear how the length of the N-terminal fragments relates to polyQ - mediated aggregation...
2017: Journal of Huntington's Disease
https://www.readbyqxmd.com/read/28333578/hormetic-heat-shock-and-hsf-1-overexpression-improve-c-elegans-survival-and-proteostasis-by-inducing-autophagy
#20
Caroline Kumsta, Malene Hansen
The cellular recycling process of macroautophagy/autophagy is an essential homeostatic system induced by various stresses, but it remains unclear how autophagy contributes to organismal stress resistance. In a recent study, we report that a mild and physiologically beneficial ("hormetic") heat shock as well as overexpression of the heat-shock responsive transcription factor HSF-1 systemically increases autophagy in C. elegans. Accordingly, we found HSF-1- and heat stress-inducible autophagy to be required for C...
March 23, 2017: Autophagy
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