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Homologous recombination

Nathaniel J Robinson, William P Schiemann
Despite significant clinical advancements, cancer remains a leading cause of mortality throughout the world due largely to the process of metastasis and the dissemination of cancer cells from their primary tumor of origin to distant secondary sites. The clinical burden imposed by metastasis is further compounded by a paucity of information regarding the factors that mediate metastatic progression. Linear chromosomes are capped by structures known as telomeres, which dictate cellular lifespan in humans by shortening progressively during successive cell divisions...
October 18, 2016: Biochimica et Biophysica Acta
Philippe Lefrançois, Beth Rockmill, Pingxing Xie, G Shirleen Roeder, Michael Snyder
During meiosis, chromosomes undergo a homology search in order to locate their homolog to form stable pairs and exchange genetic material. Early in prophase, chromosomes associate in mostly non-homologous pairs, tethered only at their centromeres. This phenomenon, conserved through higher eukaryotes, is termed centromere coupling in budding yeast. Both initiation of recombination and the presence of homologs are dispensable for centromere coupling (occurring in spo11 mutants and haploids induced to undergo meiosis) but the presence of the synaptonemal complex (SC) protein Zip1 is required...
October 2016: PLoS Genetics
Ashton A Connor, Robert E Denroche, Gun Ho Jang, Lee Timms, Sangeetha N Kalimuthu, Iris Selander, Treasa McPherson, Gavin W Wilson, Michelle A Chan-Seng-Yue, Ivan Borozan, Vincent Ferretti, Robert C Grant, Ilinca M Lungu, Eithne Costello, William Greenhalf, Daniel Palmer, Paula Ghaneh, John P Neoptolemos, Markus Buchler, Gloria Petersen, Sarah Thayer, Michael A Hollingsworth, Alana Sherker, Daniel Durocher, Neesha Dhani, David Hedley, Stefano Serra, Aaron Pollett, Michael H A Roehrl, Prashant Bavi, John M S Bartlett, Sean Cleary, Julie M Wilson, Ludmil B Alexandrov, Malcolm Moore, Bradly G Wouters, John D McPherson, Faiyaz Notta, Lincoln D Stein, Steven Gallinger
Importance: Outcomes for patients with pancreatic ductal adenocarcinoma (PDAC) remain poor. Advances in next-generation sequencing provide a route to therapeutic approaches, and integrating DNA and RNA analysis with clinicopathologic data may be a crucial step toward personalized treatment strategies for this disease. Objective: To classify PDAC according to distinct mutational processes, and explore their clinical significance. Design, Setting, and Participants: We performed a retrospective cohort study of resected PDAC, using cases collected between 2008 and 2015 as part of the International Cancer Genome Consortium...
October 20, 2016: JAMA Oncology
Kristin Bösch, Lamprinos Frantzeskakis, Miroslav Vraneš, Jörg Kämper, Kerstin Schipper, Vera Göhre
Gene deletion plays an important role in the analysis of gene function. One of the most efficient methods to disrupt genes in a targeted manner is the replacement of the entire gene with a selectable marker via homologous recombination. During homologous recombination, exchange of DNA takes place between sequences with high similarity. Therefore, linear genomic sequences flanking a target gene can be used to specifically direct a selectable marker to the desired integration site. Blunt ends of the deletion construct activate the cell's DNA repair systems and thereby promote integration of the construct either via homologous recombination or by non-homologous-end-joining...
September 30, 2016: Journal of Visualized Experiments: JoVE
James West, W Warren Gill
Genome editing in large animals has tremendous practical applications, from more accurate models for medical research through improved animal welfare and production efficiency. Although genetic modification in large animals has a 30 year history, until recently technical issues limited its utility. The original methods - pronuclear injection and integrating viruses - were plagued with problems associated with low efficiency, silencing, poor regulation of gene expression, and variability associated with random integration...
June 2016: Journal of Equine Veterinary Science
Andrea Krumm, Wynand P Roos
Here we describe the method used in our laboratory for determining the activity of homologous recombination repair of DNA double-strand breaks in cell lines. This plasmid-based method, first published by Pierce et al. 1999 from Maria Jasin's laboratory, is used along with flow cytometry for demonstrating the positive regulation of class I histone deacetylases on the repair of DNA double-strand breaks by homologous recombination.
2017: Methods in Molecular Biology
Mi-Sun Kwon, Jaewon Min, Hee-Yeon Jeon, Kwangwoo Hwang, Chuna Kim, Junho Lee, Je-Gun Joung, Woong-Yang Park, Hyunsook Lee
BRCA2 is a multifunctional tumor suppressor involved in homologous recombination (HR), mitotic checkpoint regulation, and telomere homeostasis. Absence of Brca2 in mice results in progressive shortening of telomeres and senescence, yet cells are prone to neoplastic transformation with elongated telomeres, suggesting that BRCA2 has positive and negative effects on telomere length regulation along the path to tumorigenesis. Using Caenorhabditis elegans as a model, we show here that depletion of BRC-2, an ortholog of BRCA2, paradoxically delays senescence in telomerase-deficient mutant worms...
October 2016: FEBS Open Bio
Fani-Marlen Roumelioti, Sotirios K Sotiriou, Vasiliki Katsini, Maria Chiourea, Thanos D Halazonetis, Sarantis Gagos
Human malignancies overcome replicative senescence either by activating the reverse-transcriptase telomerase or by utilizing a homologous recombination-based mechanism, referred to as alternative lengthening of telomeres (ALT). In budding yeast, ALT exhibits features of break-induced replication (BIR), a repair pathway for one-ended DNA double-strand breaks (DSBs) that requires the non-essential subunit Pol32 of DNA polymerase delta and leads to conservative DNA replication. Here, we examined whether ALT in human cancers also exhibits features of BIR A telomeric fluorescence in situ hybridization protocol involving three consecutive staining steps revealed the presence of conservatively replicated telomeric DNA in telomerase-negative cancer cells...
October 19, 2016: EMBO Reports
Friederike Finsterbusch, Ramya Ravindranathan, Ihsan Dereli, Marcello Stanzione, Daniel Tränkner, Attila Tóth
Orderly chromosome segregation during the first meiotic division requires meiotic recombination to form crossovers between homologous chromosomes (homologues). Members of the minichromosome maintenance (MCM) helicase family have been implicated in meiotic recombination. In addition, they have roles in initiation of DNA replication, DNA mismatch repair and mitotic DNA double-strand break repair. Here, we addressed the function of MCMDC2, an atypical yet conserved MCM protein, whose function in vertebrates has not been reported...
October 2016: PLoS Genetics
Sarah Röhrig, Susan Schröpfer, Alexander Knoll, Holger Puchta
The stability of repetitive sequences in complex eukaryotic genomes is safeguarded by factors suppressing homologues recombination. Prominent in this is the role of the RTR complex. In plants, it consists of the RecQ helicase RECQ4A, the topoisomerase TOP3α and RMI1. Like mammals, but not yeast, plants harbor an additional complex partner, RMI2. Here, we demonstrate that, in Arabidopsis thaliana, RMI2 is involved in the repair of aberrant replication intermediates in root meristems as well as in intrastrand crosslink repair...
October 2016: PLoS Genetics
Robert L Dilley, Priyanka Verma, Nam Woo Cho, Harrison D Winters, Anne R Wondisford, Roger A Greenberg
Homology-directed DNA repair is essential for genome maintenance through templated DNA synthesis. Alternative lengthening of telomeres (ALT) necessitates homology-directed DNA repair to maintain telomeres in about 10-15% of human cancers. How DNA damage induces assembly and execution of a DNA replication complex (break-induced replisome) at telomeres or elsewhere in the mammalian genome is poorly understood. Here we define break-induced telomere synthesis and demonstrate that it utilizes a specialized replisome, which underlies ALT telomere maintenance...
October 19, 2016: Nature
Vincenzo Sannino, Arun M Kolinjivadi, Giorgio Baldi, Vincenzo Costanzo
The correct duplication of genetic information is essential to maintain genome stability, which is lost in cancer cells. Replication fork integrity is ensured by a number of DNA metabolism proteins that assist replication of chromatin regions difficult to replicate due to their intrinsic DNA sequence composition, coordinate repair of DNA molecules resulting from aberrant replication events or protect replication forks in the presence of lesions impairing their progression. Some DNA metabolism genes involved in DNA repair are essential in higher eukaryotes even in unchallenged conditions, suggesting the existence of biological processes requiring these specialized functions in organisms with complex genomes...
2016: International Journal of Developmental Biology
Masaki Odahara, Yusuke Kobayashi, Toshiharu Shikanai, Yoshiki Nishimura
The chloroplast (cp) genome is organized as nucleoids that are dispersed throughout the cp stroma. Previously, a cp homolog of bacterial recombinase RecA (cpRECA) was shown to be involved in maintenance of cp genome integrity by repairing damaged cpDNA and by suppressing aberrant recombination between short dispersed repeats (SDRs) in the moss Physcomitrella patens. Here, overexpression and knockdown analysis of cpRECA in the green alga Chlamydomonas reinhardtii revealed that cpRECA was involved in cp nucleoid dynamics as well as having a role in maintaining cp genome integrity...
October 17, 2016: Plant Physiology
Soledad Sagastume, Raquel Martín-Hernández, Mariano Higes, Nuno Henriques-Gil
BACKGROUND: There is great controversy as to whether Microsporidia undergo a sexual cycle. In the paradigmatic case of Nosema ceranae, although there is no morphological evidence of sex, some meiosis-specific genes are present in its reduced genome and there is also high intraspecific variability, with incongruent phylogenies having been systematically obtained. The possibility of sexual recombination is important from an epidemiological standpoint, particularly as N. ceranae is considered to be a major factor in the current disquieting epidemic of widespread bee colony losses...
October 18, 2016: BMC Evolutionary Biology
Gabriela Barcenas-Morales, Peter Jandus, Rainer Döffinger
PURPOSE OF REVIEW: Concise overview of the field of anticytokine autoantibodies with a focus on recent developments. RECENT FINDINGS: Advances in particular in the analysis of autoantibodies to IFNγ, granulocyte-macrophage colony-stimulating factor (GM-CSF) and IFN-1 are presented. The target epitope for anti-IFNγ autoantibodies has been found to have high homology to a protein from Aspergillus suggesting molecular mimicry as a mechanism of breaking self-tolerance...
October 13, 2016: Current Opinion in Allergy and Clinical Immunology
Anya Alayev, Rachel S Salamon, Subrata Manna, Naomi S Schwartz, Adi Y Berman, Marina K Holz
Homologous recombination (HR) is a conserved process that maintains genome stability and cell survival by repairing DNA double-strand breaks (DSBs). The RAD51-related family of proteins is involved in repair of DSBs; consequently, deregulation of RAD51 causes chromosomal rearrangements and stimulates tumorigenesis. RAD51C has been identified as a potential tumor suppressor and a breast and ovarian cancer susceptibility gene. Recent studies have also implicated estrogen as a DNA-damaging agent that causes DSBs...
October 18, 2016: Cell Cycle
Ji-Hua Yu, Yang-Yang Li, Mian Xiang, Jian-Quan Zhu, Xin-He Huang, Wan-Jun Wang, Rui Tan, Jia-Yu Zhou, Hai Liao
OBJECTIVES: To clone and characterize a novel bi-functional α-amylase/subtilisin inhibitor (LASI) from the rhizome of Ligusticum chuanxiong, a traditional Chinese medicine. RESULTS: The LASI showed strong homology with members of the Kunitz trypsin inhibitor family. Its putative amino acid sequence has a 40 % identity with that of the α-amylase/subtilisin inhibitor from rice. LASI gene without signal peptide was expressed in E. coli Rosetta. After purification, the recombinant LASI protein was inhibitory against not only α-amylase from porcine pancreas, Helicoverpa armigera, Spodoptera litura and Plutella xylostella, but also subtilisin A, but not against trypsin or chymotrypsin...
October 17, 2016: Biotechnology Letters
Javaid Ali Gadahi, Muhammad Ehsan, Shuai Wang, ZhenChao Zhang, Yujian Wang, RuoFeng Yan, XiaoKai Song, LiXin Xu, XiangRui Li
14-3-3 proteins have been found to be an excreted/secreted antigen and assumed to be released into the host-parasite interface and described in several unicellular and multicellular parasites. However, little is known about the immunomodulatory effects of H. controtus 14-3-3 protein on host cell. In present study, 14-3-3 isoform 2 gene, designated as Hcftt-2, was amplified by reverse transcription-polymerase chain reaction (RT-PCR) from the adult H. contortus cDNA and cloned into expression plasmid pET32a (+) and expression of the recombinant protein (rHcftt-2) was induced by IPTG...
October 14, 2016: Experimental Parasitology
Elena Castro, Joaquin Mateo, David Olmos, Johann S de Bono
Several genomic studies have identified DNA repair gene defects in prostate cancer in the last 5 years. The mechanisms by which these DNA repair defects promote carcinogenesis and tumor progression in the prostate have not been fully elucidated, but their presence in at least 20-25% of metastatic castration-resistant prostate cancers (CRPCs) provides an opportunity for a therapeutic strategy that turns a tumor strength into its weakness and may lead to arguably the first molecularly stratified treatment for this disease...
September 2016: Cancer Journal
Min Pang, Xin-Yan Bai, Yan Li, Ji-Zhong Bai, Li-Rong Yuan, Shou-An Ren, Xiao-Yun Hu, Xin-Ri Zhang, Bao-Feng Yu, Rui Guo, Hai-Long Wang
Clara cell protein (CC16) is an anti-inflammatory protein, which is expressed in the airway epithelium. It is involved in the development of airway inflammatory diseases, including chronic obstructive pulmonary disease and asthma. However, the exact molecular mechanism underlying its anti‑inflammatory action remains to be fully elucidated. The aim of the present study was to define the protein profiles of the anti‑inflammatory effect of CC16 in lipopolysaccharide (LPS)‑treated rat tracheal epithelial (RTE) cells using shotgun proteomics...
October 12, 2016: Molecular Medicine Reports
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