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Nonsense suppression

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https://www.readbyqxmd.com/read/28323884/a-system-for-coordinated-analysis-of-translational-readthrough-and-nonsense-mediated-mrna-decay
#1
Stacey L Baker, J Robert Hogg
The nonsense-mediated mRNA decay (NMD) pathway degrades mRNAs containing premature termination codons, limiting the expression of potentially deleterious truncated proteins. This activity positions the pathway as a regulator of the severity of genetic diseases caused by nonsense mutations. Because many genetic diseases result from nonsense alleles, therapeutics inducing readthrough of premature termination codons and/or inhibition of NMD have been of great interest. Several means of enhancing translational readthrough have been reported to concomitantly inhibit NMD efficiency, but tools for systematic analysis of mammalian NMD inhibition by translational readthrough are lacking...
2017: PloS One
https://www.readbyqxmd.com/read/28318500/mutations-in-tmem260-cause-a-pediatric-neurodevelopmental-cardiac-and-renal-syndrome
#2
Asaf Ta-Shma, Tahir N Khan, Asaf Vivante, Jason R Willer, Pavle Matak, Chaim Jalas, Ben Pode-Shakked, Yishay Salem, Yair Anikster, Friedhelm Hildebrandt, Nicholas Katsanis, Orly Elpeleg, Erica E Davis
Despite the accelerated discovery of genes associated with syndromic traits, the majority of families affected by such conditions remain undiagnosed. Here, we employed whole-exome sequencing in two unrelated consanguineous kindreds with central nervous system (CNS), cardiac, renal, and digit abnormalities. We identified homozygous truncating mutations in TMEM260, a locus predicted to encode numerous splice isoforms. Systematic expression analyses across tissues and developmental stages validated two such isoforms, which differ in the utilization of an internal exon...
March 11, 2017: American Journal of Human Genetics
https://www.readbyqxmd.com/read/28289221/gentamicin-b1-is-a-minor-gentamicin-component-with-major-nonsense-mutation-suppression-activity
#3
Alireza Baradaran-Heravi, Jürgen Niesser, Aruna D Balgi, Kunho Choi, Carla Zimmerman, Andrew P South, Hilary J Anderson, Natalie C Strynadka, Marcel B Bally, Michel Roberge
Nonsense mutations underlie about 10% of rare genetic disease cases. They introduce a premature termination codon (PTC) and prevent the formation of full-length protein. Pharmaceutical gentamicin, a mixture of several related aminoglycosides, is a frequently used antibiotic in humans that can induce PTC readthrough and suppress nonsense mutations at high concentrations. However, testing of gentamicin in clinical trials has shown that safe doses of this drug produce weak and variable readthrough activity that is insufficient for use as therapy...
March 13, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28277935/the-pre-mrna-retention-and-splicing-complex-controls-expression-of-the-mediator-subunit-med20
#4
Yang Zhou, Marcus J O Johansson
The heterotrimeric pre-mRNA retention and splicing (RES) complex, consisting of Bud13p, Snu17p and Pml1p, promotes splicing and nuclear retention of a subset of intron-containing pre-mRNAs. Yeast cells deleted for individual RES genes show growth defects that are exacerbated at elevated temperatures. Although the growth phenotypes correlate to the splicing defects in the individual mutants, the underlying mechanism is unknown. Here, we show that the temperature sensitive (Ts) growth phenotype of bud13Δ and snu17Δ cells is a consequence of inefficient splicing of MED20 pre-mRNA, which codes for a subunit of the Mediator complex; a co-regulator of RNA polymerase II transcription...
February 17, 2017: RNA Biology
https://www.readbyqxmd.com/read/28264986/a-truncating-mutation-in-cep55-is-the-likely-cause-of-march-a-novel-syndrome-affecting-neuronal-mitosis
#5
Patrick Frosk, Heleen H Arts, Julien Philippe, Carter S Gunn, Emma L Brown, Bernard Chodirker, Louise Simard, Jacek Majewski, Somayyeh Fahiminiya, Chad Russell, Yangfan P Liu, Robert Hegele, Nicholas Katsanis, Conrad Goerz, Marc R Del Bigio, Erica E Davis
BACKGROUND: Hydranencephaly is a congenital anomaly leading to replacement of the cerebral hemispheres with a fluid-filled cyst. The goals of this work are to describe a novel autosomal-recessive syndrome that includes hydranencephaly (multinucleated neurons, anhydramnios, renal dysplasia, cerebellar hypoplasia and hydranencephaly (MARCH)); to identify its genetic cause(s) and to provide functional insight into pathomechanism. METHODS: We used homozygosity mapping and exome sequencing to identify recessive mutations in a single family with three affected fetuses...
March 6, 2017: Journal of Medical Genetics
https://www.readbyqxmd.com/read/28264473/future-of-the-genetic-code
#6
REVIEW
Hong Xue, J Tze-Fei Wong
The methods for establishing synthetic lifeforms with rewritten genetic codes comprising non-canonical amino acids (NCAA) in addition to canonical amino acids (CAA) include proteome-wide replacement of CAA, insertion through suppression of nonsense codon, and insertion via the pyrrolysine and selenocysteine pathways. Proteome-wide reassignments of nonsense codons and sense codons are also under development. These methods enable the application of NCAAs to enrich both fundamental and applied aspects of protein chemistry and biology...
February 28, 2017: Life
https://www.readbyqxmd.com/read/28188297/alternative-splicing-in-the-cytochrome-p450-superfamily-expands-protein-diversity-to-augment-gene-function-and-redirect-human-drug-metabolism
#7
Andrew J Annalora, Craig B Marcus, Patrick L Iversen
The human genome encodes 57 cytochrome P450 (CYP) genes whose enzyme products metabolize hundreds of drugs, thousands of xenobiotics and unknown numbers of endogenous compounds including steroids, retinoids and icosinoids. Indeed, CYP genes are the first line of defense against daily environmental chemical challenges in a manner that parallels the immune system. Several databases, including PubMed, AceView, and Ensembl, were queried to establish a comprehensive analysis of the full human CYP transcriptome. This review describes a remarkable diversification of the 57 human CYP genes, which may be alternatively processed into nearly 1000 distinct mRNA transcripts to shape an individual's CYP proteome...
February 10, 2017: Drug Metabolism and Disposition: the Biological Fate of Chemicals
https://www.readbyqxmd.com/read/28178277/paucity-of-intact-non-induced-provirus-with-early-long-term-antiretroviral-therapy-of-perinatal-hiv-infection
#8
Kaitlin Rainwater-Lovett, Carrie Ziemniak, Douglas Watson, Katherine Luzuriaga, George Siberry, Ann Petru, YaHui Chen, Priyanka Uprety, Margaret McManus, Ya-Chi Ho, Susanna L Lamers, Deborah Persaud
The latent reservoir is a major barrier to HIV eradication. Reservoir size is emerging as an important biomarker to assess the likelihood of HIV remission in the absence of antiretroviral therapy (ART) and may be reduced by earlier initiation of ART that restricts HIV spread into CD4+ T cells. Reservoir size is traditionally measured with a quantitative viral outgrowth assay (QVOA) that induces replication-competent HIV production through in vitro stimulation of resting CD4+ T cells. However, the recent identification of replication-intact, non-induced proviral genomes (NIPG) suggests the QVOA significantly underestimates (by 62-fold) latent reservoir size in chronically-infected adults...
2017: PloS One
https://www.readbyqxmd.com/read/28165652/candidate-susceptibility-variants-for-esophageal-squamous-cell-carcinoma
#9
Iikki Donner, Riku Katainen, Tomas Tanskanen, Eevi Kaasinen, Mervi Aavikko, Kristian Ovaska, Miia Artama, Eero Pukkala, Lauri A Aaltonen
Esophageal cancer is common worldwide, and often fatal. The major histological subtype is esophageal squamous cell carcinoma (ESCC). ESCC shows familial aggregation and high heritability. Mutations in RHBDF2 cause tylosis, a very rare disorder characterized by high life-time risk of ESCC, but no other well-established predisposition genes have been identified. To identify candidate susceptibility variants for ESCC we utilized the Population Information System and the Finnish cancer registry to find study materials by clustering ESCC patients by family name at birth and municipality at birth...
February 6, 2017: Genes, Chromosomes & Cancer
https://www.readbyqxmd.com/read/28145797/characterization-of-new-generation-aminoglycoside-promoting-premature-termination-codon-readthrough-in-cancer-cells
#10
Laure Bidou, Olivier Bugaud, Valery Belakhov, Timor Baasov, Olivier Namy
Nonsense mutations, generating premature termination codons (PTCs), account for 10% to 30% of the mutations in tumor suppressor genes. Nonsense translational suppression, induced by small molecules including gentamicin and G418, has been suggested as a potential therapy to counteract the deleterious effects of nonsense mutations in several genetic diseases and cancers. We describe here that NB124, a synthetic aminoglycoside derivative recently developed especially for PTC suppression, strongly induces apoptosis in human tumor cells by promoting high level of PTC readthrough...
March 4, 2017: RNA Biology
https://www.readbyqxmd.com/read/28121133/probing-the-structural-mechanism-of-partial-agonism-in-glycine-receptors-using-the-fluorescent-artificial-amino-acid-anap
#11
Ming S Soh, Argel Estrada-Mondragon, Nela Durisic, Angelo Keramidas, Joseph W Lynch
The efficacy of an agonist at a pentameric ligand-gated ion channel is determined by the rate at which it induces a conformational change from the resting closed state to a preopen ("flip") state. If the ability of an agonist to promote this isomerization is sufficiently low, then it becomes a partial agonist. As partial agonists at pentameric ligand-gated ion channels show considerable promise as therapeutics, understanding the structural basis of the resting-flip-state isomerization may provide insight into therapeutic design...
February 2, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28105933/haploid-yeast-cells-undergo-a-reversible-phenotypic-switch-associated-with-chromosome-ii-copy-number
#12
Polina Drozdova, Ludmila Mironova, Galina Zhouravleva
BACKGROUND: SUP35 and SUP45 are essential genes encoding polypeptide chain release factors. However, mutants for these genes may be viable but display pleiotropic phenotypes which include, but are not limited to, nonsense suppressor phenotype due to translation termination defect. [PSI (+)] prion formation is another Sup35p-associated mechanism leading to nonsense suppression through decreased availability of functional Sup35p. [PSI (+)] differs from genuine sup35 mutations by the possibility of its elimination and subsequent re-induction...
December 22, 2016: BMC Genetics
https://www.readbyqxmd.com/read/28096462/unique-contributions-of-an-arginine-side-chain-to-ligand-recognition-in-a-glutamate-gated-chloride-channel
#13
Timothy Lynagh, Vitaly V Komnatnyy, Stephan A Pless
Glutamate recognition by neurotransmitter receptors often relies on Arg residues in the binding site, leading to the assumption that charge-charge interactions underlie ligand recognition. However, assessing the precise chemical contribution of Arg side chains to protein function and pharmacology has proven to be exceedingly difficult in such large and complex proteins. Using the in vivo nonsense suppression approach, we report the first successful incorporation of the isosteric, titratable Arg analog, canavanine, into a neurotransmitter receptor in a living cell, utilizing a glutamate-gated chloride channel from the nematode Haemonchus contortus Our data unveil a surprisingly small contribution of charge at a conserved arginine side chain previously suggested to form a salt bridge with the ligand, glutamate...
March 3, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28077719/suppressing-n-acetyl-l-aspartate-synthesis-prevents-loss-of-neurons-in-a-murine-model-of-canavan-leukodystrophy
#14
Jiho Sohn, Peter Bannerman, Fuzheng Guo, Travis Burns, Laird Miers, Christopher Croteau, Naveen K Singhal, Jennifer A McDonough, David Pleasure
Canavan disease is a leukodystrophy caused by aspartoacylase (ASPA) deficiency. The lack of functional ASPA, an enzyme enriched in oligodendroglia that cleaves N-acetyl-l-aspartate (NAA) to acetate and l-aspartic acid, elevates brain NAA and causes "spongiform" vacuolation of superficial brain white matter and neighboring gray matter. In children with Canavan disease, neuroimaging shows early-onset dysmyelination and progressive brain atrophy. Neuron loss has been documented at autopsy in some cases. Prior studies have shown that mice homozygous for the Aspa nonsense mutation Nur7 also develop brain vacuolation...
January 11, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28069571/apc-c-dysfunction-limits-excessive-cancer-chromosomal-instability
#15
Laurent Sansregret, James O Patterson, Sally Dewhurst, Carlos López-García, André Koch, Nicholas McGranahan, William Chong Hang Chao, David J Barry, Andrew Rowan, Rachael Instrell, Stuart Horswell, Michael Way, Michael Howell, Martin R Singleton, René H Medema, Paul Nurse, Mark Petronczki, Charles Swanton
Intercellular heterogeneity, exacerbated by chromosomal instability (CIN), fosters tumor heterogeneity and drug resistance. However, extreme CIN correlates with improved cancer outcome, suggesting that karyotypic diversity required to adapt to selection pressures might be balanced in tumors against the risk of excessive instability. Here, we used a functional genomics screen, genome editing, and pharmacologic approaches to identify CIN-survival factors in diploid cells. We find partial anaphase-promoting complex/cyclosome (APC/C) dysfunction lengthens mitosis, suppresses pharmacologically induced chromosome segregation errors, and reduces naturally occurring lagging chromosomes in cancer cell lines or following tetraploidization...
February 2017: Cancer Discovery
https://www.readbyqxmd.com/read/28065590/mechanism-and-evidence-of-nonsense-suppression-therapy-for-genetic-eye-disorders
#16
REVIEW
Rose Richardson, Matthew Smart, Dhani Tracey-White, Andrew R Webster, Mariya Moosajee
Between 5 and 70% of genetic disease is caused by in-frame nonsense mutations, which introduce a premature termination codon (PTC) within the disease-causing gene. Consequently, during translation, non-functional or gain-of-function truncated proteins of pathological significance, are formed. Approximately 50% of all inherited retinal disorders have been associated with PTCs, highlighting the importance of novel pharmacological or gene correction therapies in ocular disease. Pharmacological nonsense suppression of PTCs could delineate a therapeutic strategy that treats the mutation in a gene- and disease-independent manner...
January 6, 2017: Experimental Eye Research
https://www.readbyqxmd.com/read/28027311/somatic-mutation-patterns-in-hemizygous-genomic-regions-unveil-purifying-selection-during-tumor-evolution
#17
Jimmy Van den Eynden, Swaraj Basu, Erik Larsson
Identification of cancer driver genes using somatic mutation patterns indicative of positive selection has become a major goal in cancer genomics. However, cancer cells additionally depend on a large number of genes involved in basic cellular processes. While such genes should in theory be subject to strong purifying (negative) selection against damaging somatic mutations, these patterns have been elusive and purifying selection remains inadequately explored in cancer. Here, we hypothesized that purifying selection should be evident in hemizygous genomic regions, where damaging mutations cannot be compensated for by healthy alleles...
December 2016: PLoS Genetics
https://www.readbyqxmd.com/read/28027291/interaction-of-prions-causes-heritable-traits-in-saccharomyces-cerevisiae
#18
Anton A Nizhnikov, Tatyana A Ryzhova, Kirill V Volkov, Sergey P Zadorsky, Julia V Sopova, Sergey G Inge-Vechtomov, Alexey P Galkin
The concept of "protein-based inheritance" defines prions as epigenetic determinants that cause several heritable traits in eukaryotic microorganisms, such as Saccharomyces cerevisiae and Podospora anserina. Previously, we discovered a non-chromosomal factor, [NSI+], which possesses the main features of yeast prions, including cytoplasmic infectivity, reversible curability, dominance, and non-Mendelian inheritance in meiosis. This factor causes omnipotent suppression of nonsense mutations in strains of S. cerevisiae bearing a deleted or modified Sup35 N-terminal domain...
December 2016: PLoS Genetics
https://www.readbyqxmd.com/read/28017590/fluorescence-amplification-method-for-forward-genetic-discovery-of-factors-in-human-mrna-degradation
#19
Andrei Alexandrov, Mei-Di Shu, Joan A Steitz
Nonsense-mediated decay (NMD) degrades mRNAs containing a premature termination codon (PTC). PTCs are a frequent cause of human genetic diseases, and the NMD pathway is known to modulate disease severity. Since partial NMD attenuation can potentially enhance nonsense suppression therapies, better definition of human-specific NMD is required. However, the majority of NMD factors were first discovered in model organisms and then subsequently identified by homology in human. Sensitivity and throughput limitations of existing approaches have hindered systematic forward genetic screening for NMD factors in human cells...
January 5, 2017: Molecular Cell
https://www.readbyqxmd.com/read/27966891/combining-sense-and-nonsense-codon-reassignment-for-site-selective-protein-modification-with-unnatural-amino-acids
#20
Zhenling Cui, Sergey Mureev, Mark E Polinkovsky, Zakir Tnimov, Zhong Guo, Thomas Durek, Alun Jones, Kirill Alexandrov
Incorporation of unnatural amino acids (uAAs) via codon reassignment is a powerful approach for introducing novel chemical and biological properties to synthesized polypeptides. However, the site-selective incorporation of multiple uAAs into polypeptides is hampered by the limited number of reassignable nonsense codons. This challenge is addressed in the current work by developing Escherichia coli in vitro translation system depleted of specific endogenous tRNAs. The translational activity in this system is dependent on the addition of synthetic tRNAs for the chosen sense codon...
December 30, 2016: ACS Synthetic Biology
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