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https://www.readbyqxmd.com/read/28231327/functionally-focused-algorithmic-analysis-of-high-resolution-microarray-cgh-genomic-landscapes-demonstrates-comparable-genomic-copy-number-aberrations-in-msi-and-mss-sporadic-colorectal-cancer
#1
Hamad Ali, Milad S Bitar, Ashraf Al Madhoun, Makia Marafie, Fahd Al-Mulla
Array-based comparative genomic hybridization (aCGH) emerged as a powerful technology for studying copy number variations at higher resolution in many cancers including colorectal cancer. However, the lack of standardized systematic protocols including bioinformatic algorithms to obtain and analyze genomic data resulted in significant variation in the reported copy number aberration (CNA) data. Here, we present genomic aCGH data obtained using highly stringent and functionally relevant statistical algorithms from 116 well-defined microsatellites instable (MSI) and microsatellite stable (MSS) colorectal cancers...
2017: PloS One
https://www.readbyqxmd.com/read/28230529/single-molecule-fret-unveils-induced-fit-mechanism-for-substrate-selectivity-in-flap-endonuclease-1
#2
Fahad Rashid, Paul D Harris, Manal S Zaher, Mohamed A Sobhy, Luay I Joudeh, Chunli Yan, Hubert Piwonski, Susan E Tsutakawa, Ivaylo Ivanov, John A Tainer, Satoshi Habuchi, Samir M Hamdan
Human flap endonuclease 1 (FEN1) and related structure-specific 5'nucleases precisely identify and incise aberrant DNA structures during replication, repair and recombination to avoid genomic instability. Yet, it is unclear how the 5'nuclease mechanisms of DNA distortion and protein ordering robustly mediate efficient and accurate substrate recognition and catalytic selectivity. Here, single-molecule sub-millisecond and millisecond analyses of FEN1 reveal a protein-DNA induced-fit mechanism that efficiently verifies substrate and suppresses off-target cleavage...
February 23, 2017: ELife
https://www.readbyqxmd.com/read/28226235/plant-mitochondrial-genomes-dynamics-and-mechanisms-of-mutation
#3
José M Gualberto, Kathleen J Newton
The large mitochondrial genomes of angiosperms are unusually dynamic because of recombination activities involving repeated sequences. These activities generate subgenomic forms and extensive genomic variation even within the same species. Such changes in genome structure are responsible for the rapid evolution of plant mitochondrial DNA and for the variants associated with cytoplasmic male sterility and abnormal growth phenotypes. Nuclear genes modulate these processes, and over the past decade, several of these genes have been identified...
February 9, 2017: Annual Review of Plant Biology
https://www.readbyqxmd.com/read/28223401/transcriptome-analyses-of-rhesus-monkey-pre-implantation-embryos-reveal-a-reduced-capacity-for-dna-double-strand-break-repair-in-primate-oocytes-and-early-embryos
#4
Xinyi Wang, Denghui Liu, Dajian He, Shengbo Suo, Xian Xia, Xiechao He, Jing-Dong Han, Ping Zheng
Pre-implantation embryogenesis encompasses several critical events including genome reprogramming, zygotic genome activation (ZGA), and cell fate commitment, most of which remain mechanistically unclear in primates. In addition, primates display a high rate of embryo wastage without any clear molecular basis. Understanding the factors involved in genome reprogramming and ZGA will help the generation of induced pluripotent stem cells with high efficiency. Moreover, explaining the molecular basis responsible for embryo wastage in primates will greatly expand our knowledge of species evolution...
February 21, 2017: Genome Research
https://www.readbyqxmd.com/read/28220356/overexpression-of-line-1-retrotransposons-in-autism-brain
#5
Svitlana Shpyleva, Stepan Melnyk, Oleksandra Pavliv, Igor Pogribny, S Jill James
Long interspersed nuclear elements-1 (LINE-1 or L1) are mobile DNA sequences that are capable of duplication and insertion (retrotransposition) within the genome. Recently, retrotransposition of L1 was shown to occur within human brain leading to somatic mosaicism in hippocampus and cerebellum. Because unregulated L1 activity can promote genomic instability and mutagenesis, multiple mechanisms including epigenetic chromatin condensation have evolved to effectively repress L1 expression. Nonetheless, L1 expression has been shown to be increased in patients with Rett syndrome and schizophrenia...
February 20, 2017: Molecular Neurobiology
https://www.readbyqxmd.com/read/28220209/s-phase-checkpoint-regulations-that-preserve-replication-and-chromosome-integrity-upon-dntp-depletion
#6
REVIEW
Michele Giannattasio, Dana Branzei
DNA replication stress, an important source of genomic instability, arises upon different types of DNA replication perturbations, including those that stall replication fork progression. Inhibitors of the cellular pool of deoxynucleotide triphosphates (dNTPs) slow down DNA synthesis throughout the genome. Following depletion of dNTPs, the highly conserved replication checkpoint kinase pathway, also known as the S-phase checkpoint, preserves the functionality and structure of stalled DNA replication forks and prevents chromosome fragmentation...
February 20, 2017: Cellular and Molecular Life Sciences: CMLS
https://www.readbyqxmd.com/read/28218681/the-intra-s-checkpoint-responses-to-dna-damage
#7
REVIEW
Divya Ramalingam Iyer, Nicholas Rhind
Faithful duplication of the genome is a challenge because DNA is susceptible to damage by a number of intrinsic and extrinsic genotoxins, such as free radicals and UV light. Cells activate the intra-S checkpoint in response to damage during S phase to protect genomic integrity and ensure replication fidelity. The checkpoint prevents genomic instability mainly by regulating origin firing, fork progression, and transcription of G1/S genes in response to DNA damage. Several studies hint that regulation of forks is perhaps the most critical function of the intra-S checkpoint...
February 17, 2017: Genes
https://www.readbyqxmd.com/read/28218666/the-ageing-brain-effects-on-dna-repair-and-dna-methylation-in-mice
#8
Sabine A S Langie, Kerry M Cameron, Gabriella Ficz, David Oxley, Bartłomiej Tomaszewski, Joanna P Gorniak, Lou M Maas, Roger W L Godschalk, Frederik J van Schooten, Wolf Reik, Thomas von Zglinicki, John C Mathers
Base excision repair (BER) may become less effective with ageing resulting in accumulation of DNA lesions, genome instability and altered gene expression that contribute to age-related degenerative diseases. The brain is particularly vulnerable to the accumulation of DNA lesions; hence, proper functioning of DNA repair mechanisms is important for neuronal survival. Although the mechanism of age-related decline in DNA repair capacity is unknown, growing evidence suggests that epigenetic events (e.g., DNA methylation) contribute to the ageing process and may be functionally important through the regulation of the expression of DNA repair genes...
February 17, 2017: Genes
https://www.readbyqxmd.com/read/28213433/chromosomal-instability-as-a-driver-of-tumor-heterogeneity-and-evolution
#9
Samuel F Bakhoum, Dan Avi Landau
Large-scale, massively parallel sequencing of human cancer samples has revealed tremendous genetic heterogeneity within individual tumors. Indeed, tumors are composed of an admixture of diverse subpopulations-subclones-that vary in space and time. Here, we discuss a principal driver of clonal diversification in cancer known as chromosomal instability (CIN), which complements other modes of genetic diversification creating the multilayered genomic instability often seen in human cancer. Cancer cells have evolved to fine-tune chromosome missegregation rates to balance the acquisition of heterogeneity while preserving favorable genotypes, a dependence that can be exploited for a therapeutic benefit...
February 17, 2017: Cold Spring Harbor Perspectives in Medicine
https://www.readbyqxmd.com/read/28212810/chromosomal-instability-analysis-and-regional-tumor-heterogeneity-in-colon-cancer
#10
Vincenza Barresi, Sergio Castorina, Nicolò Musso, Carmela Capizzi, Tonia Luca, Giovanna Privitera, Daniele Filippo Condorelli
Chromosomal instability (CIN) is classically defined as an increase in the rate at which numerical or structural chromosomal aberrations are acquired in a cancer cell. The number of somatic copy number abnormalities (CNAs) revealed by high resolution genomic array can be considered as a surrogate marker for CIN, but several points, related to sample processing and data analysis, need to be standardized. In this work we analyzed 51 CRC samples and matched normal mucosae by whole genome SNP arrays and compared different bioinformatics tools in order to identify broad (>25% of a chromosomal arm) and focal somatic copy number abnormalities (BCNAs and FCNAs respectively)...
January 2017: Cancer Genetics
https://www.readbyqxmd.com/read/28203566/increased-spontaneous-recombination-in-rnase-h2-deficient-cells-arises-from-multiple-contiguous-rnmps-and-not-from-single-rnmp-residues-incorporated-by-dna-polymerase-epsilon
#11
Anastasiya Epshtein, Catherine J Potenski, Hannah L Klein
Ribonucleotides can become embedded in DNA from insertion by DNA polymerases, failure to remove Okazaki fragment primers, R-loops that can prime replication, and RNA/cDNA-mediated recombination. RNA:DNA hybrids are removed by RNase H enzymes. Single rNMPs in DNA are removed by RNase H2 and if they remain on the leading strand, can lead to mutagenesis in a Top1-dependent pathway. rNMPs in DNA can also stimulate genome instability, among which are homologous recombination gene conversion events. We previously found that, similar to the rNMP-stimulated mutagenesis, rNMP-stimulated recombination was also Top1-dependent...
June 2016: Microbial Cell
https://www.readbyqxmd.com/read/28202506/recurrent-patterns-of-dna-copy-number-alterations-in-tumors-reflect-metabolic-selection-pressures
#12
Nicholas A Graham, Aspram Minasyan, Anastasia Lomova, Ashley Cass, Nikolas G Balanis, Michael Friedman, Shawna Chan, Sophie Zhao, Adrian Delgado, James Go, Lillie Beck, Christian Hurtz, Carina Ng, Rong Qiao, Johanna Ten Hoeve, Nicolaos Palaskas, Hong Wu, Markus Müschen, Asha S Multani, Elisa Port, Steven M Larson, Nikolaus Schultz, Daniel Braas, Heather R Christofk, Ingo K Mellinghoff, Thomas G Graeber
Copy number alteration (CNA) profiling of human tumors has revealed recurrent patterns of DNA amplifications and deletions across diverse cancer types. These patterns are suggestive of conserved selection pressures during tumor evolution but cannot be fully explained by known oncogenes and tumor suppressor genes. Using a pan-cancer analysis of CNA data from patient tumors and experimental systems, here we show that principal component analysis-defined CNA signatures are predictive of glycolytic phenotypes, including (18)F-fluorodeoxy-glucose (FDG) avidity of patient tumors, and increased proliferation...
February 15, 2017: Molecular Systems Biology
https://www.readbyqxmd.com/read/28202223/filtration-based-enrichment-of-circulating-tumor-cells-from-all-prostate-cancer-risk-groups
#13
Julius Adebayo Awe, Jeff Saranchuk, Darrel Drachenberg, Sabine Mai
OBJECTIVE: To combine circulating tumor cell (CTC) isolation by filtration and immunohistochemistry to investigate the presence of CTCs in low, intermediate, and high-risk prostate cancer (PCa). CTCs isolated from these risk groups stained positive for both cytokeratin and androgen receptors, but negative for CD45. PATIENTS AND METHODS: Blood samples from 41 biopsy confirmed patients with PCa at different clinical stages such as low, intermediate, and high risk were analyzed...
February 12, 2017: Urologic Oncology
https://www.readbyqxmd.com/read/28199992/fragile-genes-that-are-frequently-altered-in-cancer-players-not-passengers
#14
Jenna R Karras, Morgan S Schrock, Bahadir Batar, Kay Huebner
FHIT, located at FRA3B, is one of the most commonly deleted genes in human cancers, and loss of FHIT protein is one of the earliest events in cancer initiation. However, location of FHIT at a chromosomal fragile site, a locus prone to breakage and gap formation under even mild replication stress, has encouraged claims that FHIT loss is a passenger event in cancers. We summarize accumulated evidence that FHIT protein functions as a genome "caretaker" required to protect the stability of genomes of normal cells of most tissues from agents causing intrinsic and extrinsic DNA damage...
February 16, 2017: Cytogenetic and Genome Research
https://www.readbyqxmd.com/read/28199840/citron-kinase-deficiency-leads-to-chromosomal-instability-and-tp53-sensitive-microcephaly
#15
Federico Tommaso Bianchi, Chiara Tocco, Gianmarco Pallavicini, Yifan Liu, Fiammetta Vernì, Chiara Merigliano, Silvia Bonaccorsi, Nadia El-Assawy, Lorenzo Priano, Marta Gai, Gaia Elena Berto, Alessandra Maria Adelaide Chiotto, Francesco Sgrò, Alessia Caramello, Laura Tasca, Ugo Ala, Francesco Neri, Salvatore Oliviero, Alessandro Mauro, Stephan Geley, Maurizio Gatti, Ferdinando Di Cunto
Mutations in citron (CIT), leading to loss or inactivation of the citron kinase protein (CITK), cause primary microcephaly in humans and rodents, associated with cytokinesis failure and apoptosis in neural progenitors. We show that CITK loss induces DNA damage accumulation and chromosomal instability in both mammals and Drosophila. CITK-deficient cells display "spontaneous" DNA damage, increased sensitivity to ionizing radiation, and defective recovery from radiation-induced DNA lesions. In CITK-deficient cells, DNA double-strand breaks increase independently of cytokinesis failure...
February 14, 2017: Cell Reports
https://www.readbyqxmd.com/read/28199309/phosphatidylinositol-3-kinase-%C3%AE-blockade-increases-genomic-instability-in-b-cells
#16
Mara Compagno, Qi Wang, Chiara Pighi, Taek-Chin Cheong, Fei-Long Meng, Teresa Poggio, Leng-Siew Yeap, Elif Karaca, Rafael B Blasco, Fernanda Langellotto, Chiara Ambrogio, Claudia Voena, Adrian Wiestner, Siddha N Kasar, Jennifer R Brown, Jing Sun, Catherine J Wu, Monica Gostissa, Frederick W Alt, Roberto Chiarle
Activation-induced cytidine deaminase (AID) is a B-cell-specific enzyme that targets immunoglobulin genes to initiate class switch recombination and somatic hypermutation. In addition, through off-target activity, AID has a much broader effect on genomic instability by initiating oncogenic chromosomal translocations and mutations involved in the development and progression of lymphoma. AID expression is tightly regulated in B cells and its overexpression leads to enhanced genomic instability and lymphoma formation...
February 15, 2017: Nature
https://www.readbyqxmd.com/read/28198347/natural-escherichia-coli-isolates-rapidly-acquire-genetic-changes-upon-laboratory-domestication
#17
Bin Liu, Gustavo Eydallin, Ram P Maharjan, Lu Feng, Lei Wang, Thomas Ferenci
The adaptation of environmental bacteria to laboratory conditions was analysed through the exploration of genomic changes in four strains of Escherichia coli freshly isolated from their natural habitats and belonging to different taxonomic clusters. Up to 25 mutations were present in all cultures of natural isolates within 10 days of transfer in rich media or with a single growth cycle involving an extended stationary phase. Among numerous individual mutations, two genes were affected in parallel in distinct backgrounds...
January 2017: Microbiology
https://www.readbyqxmd.com/read/28197627/copy-number-analysis-identifies-tumor-suppressive-lncrnas-in-human-osteosarcoma
#18
Jianjun Xie, Dechen Lin, Dhong Hyun Tony Lee, Jennifer Akunowicz, Marc Hansen, Carl Miller, Masashi Sanada, Motohiro Kato, Tadayuki Akagi, Norihiko Kawamata, Seishi Ogawa, H Phillip Koeffler
Osteosarcoma (OS) has a high degree of chromosomal instability and total copy number (CN) changes. We examined 58 human OS samples including 40 primary tumors, 11 explants, and 7 cell lines using single nucleotide polymorphism (SNP) arrays, and revealed that 70% of the samples had one or more recurrent CN-neutral loss of heterozygosity (CNN‑LOH) also known as uniparental disomy (UPD). Importantly, 17% of the samples showed prominent homozygous deletion of 3q13.31, suggesting its role in tumorigenesis. We identified and characterized two novel lncRNAs, LOC285194 and BC040587, within this genomic locus, strongly suggesting their tumor suppressor activity...
March 2017: International Journal of Oncology
https://www.readbyqxmd.com/read/28197541/way-out-way-in-how-the-relationship-between-wrn-and-cdk1-may-change-the-fate-of-collapsed-replication-forks
#19
Valentina Palermo, Sara Rinalducci, Massimo Sanchez, Francesca Grillini, Annapaola Franchitto, Pietro Pichierri
Replication-dependent double-strand breaks (DSBs) are the main source of genomic instability as their inaccurate repair stimulates chromosomal rearrangements. In a recent work, we uncover a novel regulatory circuit that involves the Werner's syndrome helicase and CDK1, and that is essential for repair pathway choice at replication-dependent DSBs.
2017: Molecular & Cellular Oncology
https://www.readbyqxmd.com/read/28196983/genomic-profiling-of-acute-lymphoblastic-leukemia-in-ataxia-telangiectasia-patients-reveals-tight-link-between-atm-mutations-and-chromothripsis
#20
M Ratnaparkhe, M Hlevnjak, T Kolb, A Jauch, K K Maass, F Devens, A Rode, V Hovestadt, A Korshunov, A Pastorczak, W Mlynarski, S Sungalee, J Korbel, J Hoell, U Fischer, T Milde, C Kramm, M Nathrath, K Chrzanowska, E Tausch, M Takagi, T Taga, S Constantini, J Loeffen, J Meijerink, S Zielen, G Gohring, B Schlegelberger, E Maass, R Siebert, J Kunz, A E Kulozik, B Worst, D T Jones, S M Pfister, M Zapatka, P Lichter, A Ernst
Recent developments in sequencing technologies led to the discovery of a novel form of genomic instability, termed chromothripsis. This catastrophic genomic event, involved in tumorigenesis, is characterized by tens to hundreds of simultaneously acquired locally clustered rearrangements on one chromosome. We hypothesized that leukemias developing in individuals with Ataxia Telangiectasia, who are born with two mutated copies of the ATM gene, an essential guardian of genome stability, would show a higher prevalence of chromothripsis due to the associated defect in DNA double-strand break repair...
February 15, 2017: Leukemia: Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K
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