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Hui Li Tong, Run Ying Jiang, Wei Wei Zhang, Yun Qin Yan
Our group previously identified miR-2425-5p, a unique bovine miRNA; however, its biological function and regulation in muscle-derived satellite cells (MDSCs) remain unclear. Herein, stem-loop RT-PCR results showed that miR-2425-5p increased during MDSCs proliferation, but decreased during differentiation. Cell proliferation was examined using EdU assays, cyclin B1 (CCNB1) and proliferating cell nuclear antigen (PCNA) western blot (WB) and flow cytometry analysis. These results showed that miR-2425-5p mimics (miR-2425-M) enhanced MDSCs proliferation, whereas, miR-2425-5p inhibitor (miR-2425-I) had opposite effect...
March 24, 2017: Scientific Reports
Rui Li, Wenguo Wang, Fosheng Li, Qingwei Wang, Shenghua Wang, Ying Xu, Fang Chen
Rad9 protein plays an important role in cell-cycle checkpoint signal transduction in human and yeast cells, but knowledge about Rad9 in plants is limited. This study reports that the Rad9 gene of rice can generate the transcript products OsRad9.1 and OsRad9.2 through alternative splicing. OsRad9.1, with all nine exons, is the main cell-cycle checkpoint protein involved in the response of rice to genotoxic stresses (ultraviolet radiation and antibiotic stress), environmental stresses (drought, salt, and heavy metal stress), and auxin stimuli (2,4-D, IAA, and IBA)...
March 16, 2017: Zeitschrift Für Naturforschung. C, A Journal of Biosciences
Yi Liu, José Renato Cussiol, Diego Dibitetto, Jennie Rae Sims, Shyam Twayana, Robert Samuel Weiss, Raimundo Freire, Federica Marini, Achille Pellicioli, Marcus Bustamante Smolka
Genome maintenance and cancer suppression require homologous recombination (HR) DNA repair. In yeast and mammals, the scaffold protein TOPBP1(Dpb11) has been implicated in HR, although its precise function and mechanism of action remain elusive. In this study, we show that yeast Dpb11 plays an antagonistic role in recombination control through regulated protein interactions. Dpb11 mediates opposing roles in DNA end resection by coordinating both the stabilization and exclusion of Rad9 from DNA lesions. The Mec1 kinase promotes the pro-resection function of Dpb11 by mediating its interaction with the Slx4 scaffold...
March 6, 2017: Journal of Cell Biology
Howard B Lieberman, Sunil K Panigrahi, Kevin M Hopkins, Li Wang, Constantinos G Broustas
The way cells respond to DNA damage is important since inefficient repair or misrepair of lesions can have deleterious consequences, including mutation, genomic instability, neurodegenerative disorders, premature aging, cancer or death. Whether damage occurs spontaneously as a byproduct of normal metabolic processes, or after exposure to exogenous agents, cells muster a coordinated, complex DNA damage response (DDR) to mitigate potential harmful effects. A variety of activities are involved to promote cell survival, and include DNA repair, DNA damage tolerance, as well as transient cell cycle arrest to provide time for repair before entry into critical cell cycle phases, an event that could be lethal if traversal occurs while damage is present...
April 2017: Radiation Research
Jasmine Siler, Bowen Xia, Carina Wong, Morgan Kath, Xin Bi
The evolutionally conserved Fun30 chromatin remodeler in Saccharomyces cerevisiae has been shown to contribute to cellular resistance to genotoxic stress inflicted by camptothecin (CPT), methyl methanesulfonate (MMS) and hydroxyurea (HU). Fun30 aids in extensive DNA resection of DNA double stranded break (DSB) ends, which is thought to underlie its role in CPT-resistance. How Fun30 promotes MMS- or HU-resistance has not been resolved. Interestingly, we have recently found Fun30 to also play a negative role in cellular tolerance to MMS and HU in the absence of the Rad5-dependent DNA damage tolerance pathway...
February 2017: DNA Repair
Benjamin Pardo, Laure Crabbé, Philippe Pasero
Eukaryotic cells activate the S-phase checkpoint in response to a variety of events affecting the progression of replication forks, collectively referred to as replication stress. This signaling pathway is divided in two branches: the DNA damage checkpoint (DDC) and the DNA replication checkpoint (DRC). Both pathways are activated by the sensor kinase Mec1 and converge on the effector kinase Rad53. However, the DDC operates throughout the cell cycle and depends on the checkpoint mediator Rad9 to activate Rad53, whereas the DRC is specific to S phase and is mediated by Mrc1 and other fork components to signal replication impediments...
March 1, 2017: FEMS Yeast Research
Thomas E Bass, Jessica W Luzwick, Gina Kavanaugh, Clinton Carroll, Huzefa Dungrawala, Gloria G Glick, Michael D Feldkamp, Reid Putney, Walter J Chazin, David Cortez
The ATR checkpoint kinase coordinates cellular responses to DNA replication stress. Budding yeast contain three activators of Mec1 (the ATR orthologue); however, only TOPBP1 is known to activate ATR in vertebrates. We identified ETAA1 as a replication stress response protein in two proteomic screens. ETAA1-deficient cells accumulate double-strand breaks, sister chromatid exchanges, and other hallmarks of genome instability. They are also hypersensitive to replication stress and have increased frequencies of replication fork collapse...
November 2016: Nature Cell Biology
Tracey Beyer, Ted Weinert
DNA replication errors at certain sites in the genome initiate chromosome instability that ultimately leads to stable genomic rearrangements. Where instability begins is often unclear. And, early instability may form unstable chromosome intermediates whose transient nature also hinders mechanistic understanding. We report here a budding yeast model that reveals the genetic ontogeny of genome rearrangements, from initial replication error to unstable chromosome formation to their resolution. Remarkably, the initial error often arises in or near the telomere, and frequently forms unstable chromosomes...
October 2016: PLoS Genetics
Nicole A Najor, Layne Weatherford, George S Brush
In the budding yeast Saccharomyces cerevisiae, unnatural stabilization of the cyclin-dependent kinase inhibitor Sic1 during meiosis can trigger extra rounds of DNA replication. When programmed DNA double-strand breaks (DSBs) are generated but not repaired due to absence of DMC1, a pathway involving the checkpoint gene RAD17 prevents this DNA rereplication. Further genetic analysis has now revealed that prevention of DNA rereplication also requires MEC1, which encodes a protein kinase that serves as a central checkpoint regulator in several pathways including the meiotic recombination checkpoint response...
December 7, 2016: G3: Genes—Genomes—Genetics
Marta Markiewicz-Potoczny, David Lydall
All organisms live in changeable, stressful environments. It has been reported that exposure to low-dose stresses or poisons can improve fitness. However, examining the effects of chronic low-dose chemical exposure is challenging. To address this issue we used temperature sensitive mutations affecting the yeast cell division cycle to induce low-dose stress for 40 generation times, or more. We examined cdc13-1 mutants, defective in telomere function, and cdc15-2 mutants, defective in mitotic kinase activity...
October 17, 2016: Cell Cycle
Yasuko Kamisugi, John W Whitaker, Andrew C Cuming
The model bryophyte Physcomitrella patens is unique among plants in supporting the generation of mutant alleles by facile homologous recombination-mediated gene targeting (GT). Reasoning that targeted transgene integration occurs through the capture of transforming DNA by the homology-dependent pathway for DNA double-strand break (DNA-DSB) repair, we analysed the genome-wide transcriptomic response to bleomycin-induced DNA damage and generated mutants in candidate DNA repair genes. Massively parallel (Illumina) cDNA sequencing identified potential participants in gene targeting...
2016: PloS One
Qing Hu, Ding Tang, Hongjun Wang, Yi Shen, Xiaojun Chen, Jianhui Ji, Guijie Du, Yafei Li, Zhukuan Cheng
During meiosis, programmed double-strand breaks (DSBs) are generated to initiate homologous recombination, which is crucial for faithful chromosome segregation. In yeast, Radiation sensitive1 (RAD1) acts together with Radiation sensitive9 (RAD9) and Hydroxyurea sensitive1 (HUS1) to facilitate meiotic recombination via cell-cycle checkpoint control. However, little is known about the meiotic functions of these proteins in higher eukaryotes. Here, we characterized a RAD1 homolog in rice (Oryza sativa) and obtained evidence that O...
October 2016: Plant Physiology
Yasunori Fukumoto, Masayoshi Ikeuchi, Yuji Nakayama, Naoto Yamaguchi
ATR-dependent DNA damage checkpoint is the major DNA damage checkpoint against UV irradiation and DNA replication stress. The Rad17-RFC and Rad9-Rad1-Hus1 (9-1-1) complexes interact with each other to contribute to ATR signaling, however, the precise regulatory mechanism of the interaction has not been established. Here, we identified a conserved sequence motif, KYxxL, in the AAA+ domain of Rad17 protein, and demonstrated that this motif is essential for the interaction with the 9-1-1 complex. We also show that UV-induced Rad17 phosphorylation is increased in the Rad17 KYxxL mutants...
September 2, 2016: Biochemical and Biophysical Research Communications
Giancarlo Barone, Christopher J Staples, Anil Ganesh, Karl W Patterson, Dominic P Bryne, Katie N Myers, Abhijit A Patil, Claire E Eyers, Sarah Maslen, J Mark Skehel, Patrick A Eyers, Spencer J Collis
Cyclin-dependent kinases (CDKs) coordinate cell cycle checkpoints with DNA repair mechanisms that together maintain genome stability. However, the myriad mechanisms that can give rise to genome instability are still to be fully elucidated. Here, we identify CDK18 (PCTAIRE 3) as a novel regulator of genome stability, and show that depletion of CDK18 causes an increase in endogenous DNA damage and chromosomal abnormalities. CDK18-depleted cells accumulate in early S-phase, exhibiting retarded replication fork kinetics and reduced ATR kinase signaling in response to replication stress...
October 14, 2016: Nucleic Acids Research
Jeziel D Damasceno, Ricardo Obonaga, Elaine V Santos, Alan Scott, Richard McCulloch, Luiz R O Tosi
The Rad9-Rad1-Hus1 (9-1-1) complex is a key component in the coordination of DNA damage sensing, cell cycle progression and DNA repair pathways in eukaryotic cells. This PCNA-related trimer is loaded onto RPA-coated single stranded DNA and interacts with ATR kinase to mediate effective checkpoint signaling to halt the cell cycle and to promote DNA repair. Beyond these core activities, mounting evidence suggests that a broader range of functions can be provided by 9-1-1 structural diversification. The protozoan parasite Leishmania is an early-branching eukaryote with a remarkably plastic genome, which hints at peculiar genome maintenance mechanisms...
September 2016: Molecular Microbiology
M Kong, L L An, Z S Hu, K M Li, Y Zhao, Z Y Cai, J Y Sun, H F Wang, S C Zhang, Z Y Zhang
OBJECTIVE: The aim of this study was to investigate the effects of Rad9 mutants with impaired DNA mismatch repair (MMR) function on the tumorigenesis of colorectal cancer. METHODS: The colorectal cancer tumor samples were collected from 100 patients. The mutation profiles of human Rad9 (hRad9) gene in these samples were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and sequencing. The plasmid of pFLAG-hRad9 (L101M) was constructed following the QuickChange mutagenesis procedure and transfected into mRad9-deleted mouse cells (mRad9(-/-) cells)...
May 23, 2016: Zhonghua Zhong Liu za Zhi [Chinese Journal of Oncology]
Mika Higashide, Miki Shinohara
The number and distribution of meiosis crossover (CO) events on each bivalent are strictly controlled by multiple mechanisms to assure proper chromosome segregation during the first meiotic division. In Saccharomyces cerevisiae, Slx4 is a multi-functional scaffold protein for structure-selective endonucleases, such as Slx1 and Rad1 (which are involved in DNA damage repair), and is also a negative regulator of the Rad9-dependent signaling pathway with Rtt107 Slx4 has been believed to play only a minor role in meiotic recombination...
2016: G3: Genes—Genomes—Genetics
Perry Tal, Shay Eizenberger, Elad Cohen, Naomi Goldfinger, Shmuel Pietrokovski, Moshe Oren, Varda Rotter
The p53 tumor suppressor serves as a major barrier against malignant transformation. Over 50% of tumors inactivate p53 by point mutations in its DNA binding domain. Most mutations destabilize p53 protein folding, causing its partial denaturation at physiological temperature. Thus a high proportion of human tumors overexpress a potential potent tumor suppressor in a non-functional, misfolded form. The equilibrium between the properly folded and misfolded states of p53 may be affected by molecules that interact with p53, stabilizing its native folding and restoring wild type p53 activity to cancer cells...
March 15, 2016: Oncotarget
Sanket Awate, Arrigo De Benedetti
BACKGROUND: The Tousled like kinase 1B (TLK1B) is critical for DNA repair and survival of cells. Upon DNA damage, Chk1 phosphorylates TLK1B at S457 leading to its transient inhibition. Once TLK1B regains its kinase activity it phosphorylates Rad9 at S328. In this work we investigated the significance of this mechanism by overexpressing mutant TLK1B in which the inhibitory phosphorylation site was eliminated. RESULTS AND DISCUSSION: These cells expressing TLK1B resistant to DNA damage showed constitutive phosphorylation of Rad9 S328 that occurred even in the presence of hydroxyurea (HU), and this resulted in a delayed checkpoint recovery...
February 9, 2016: BMC Molecular Biology
X-J Peng, S-J Liu, C-M Bao, Y-Z Liu, H-W Xie, Y-H Cai, B-M Li, H-Y Hang, X Ding
Genotoxic stress activates checkpoint signaling pathways that activate the checkpoint kinases ATM and ATR, halt cell cycle progression, and promote DNA repair. A number of proteins act in concert with ATR to phosphorylate Chk1, including RAD17, the RAD9-RAD1-HUS1 complex, ATR/ATRIP and TopBp1. However, how these proteins involved act in concert with one another to propagate and maintain the checkpoint response is not well understood. Here, we reported that upregulation of RAD9 protein increased the quantity of ATRIP, suggesting that RAD9 activation will induce more efficient accumulation of ATRIP in vivo...
December 9, 2015: Cellular and Molecular Biology
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