Maintenance of Genome Integrity: DNA Damage Sensing, Signaling, Repair and Replication in Plants

Maintenance of Genome Integrity: DNA Damage Sensing, Signaling, Repair and Replication in Plants
Author: Alma Balestrazzi
Publisher: Frontiers Media SA
Total Pages: 131
Release: 2016-05-06
Genre: Botany
ISBN: 2889198200

Download Maintenance of Genome Integrity: DNA Damage Sensing, Signaling, Repair and Replication in Plants Book in PDF, Epub and Kindle

Environmental stresses and metabolic by-products can severely affect the integrity of genetic information by inducing DNA damage and impairing genome stability. As a consequence, plant growth and productivity are irreversibly compromised. To overcome genotoxic injury, plants have evolved complex strategies relying on a highly efficient repair machinery that responds to sophisticated damage perception/signaling networks. The DNA damage signaling network contains several key components: DNA damage sensors, signal transducers, mediators, and effectors. Most of these components are common to other eukaryotes but some features are unique to the plant kingdom. ATM and ATR are well-conserved members of PIKK family, which amplify and transduce signals to downstream effectors. ATM primarily responds to DNA double strand breaks while ATR responds to various forms of DNA damage. The signals from the activated transducer kinases are transmitted to the downstream cell-cycle regulators, such as CHK1, CHK2, and p53 in many eukaryotes. However, plants have no homologue of CHK1, CHK2 nor p53. The finding of Arabidopsis transcription factor SOG1 that seems functionally but not structurally similar to p53 suggests that plants have developed unique cell cycle regulation mechanism. The double strand break repair, recombination repair, postreplication repair, and lesion bypass, have been investigated in several plants. The DNA double strand break, a most critical damage for organisms are repaired non-homologous end joining (NHEJ) or homologous recombination (HR) pathway. Damage on template DNA makes replication stall, which is processed by translesion synthesis (TLS) or error-free postreplication repair (PPR) pathway. Deletion of the error-prone TLS polymerase reduces mutation frequencies, suggesting PPR maintains the stalled replication fork when TLS is not available. Unveiling the regulation networks among these multiple pathways would be the next challenge to be completed. Some intriguing issues have been disclosed such as the cross-talk between DNA repair, senescence and pathogen response and the involvement of non-coding RNAs in global genome stability. Several studies have highlighted the essential contribution of chromatin remodeling in DNA repair DNA damage sensing, signaling and repair have been investigated in relation to environmental stresses, seed quality issues, mutation breeding in both model and crop plants and all these studies strengthen the idea that components of the plant response to genotoxic stress might represent tools to improve stress tolerance and field performance. This focus issue gives researchers the opportunity to gather and interact by providing Mini-Reviews, Commentaries, Opinions, Original Research and Method articles which describe the most recent advances and future perspectives in the field of DNA damage sensing, signaling and repair in plants. A comprehensive overview of the current progresses dealing with the genotoxic stress response in plants will be provided looking at cellular and molecular level with multidisciplinary approaches. This will hopefully bring together valuable information for both plant biotechnologists and breeders.

The Evolving Telomeres

The Evolving Telomeres
Author: Arthur J. Lustig
Publisher: Frontiers Media SA
Total Pages: 76
Release: 2016-07-19
Genre: Genetics
ISBN: 2889198812

Download The Evolving Telomeres Book in PDF, Epub and Kindle

What controls the different rates of evolution to give rise to conserved and divergent proteins and RNAs? How many trials until evolution can adapt to physiological changes? Every organism has arisen through multiple molecular changes, and the mechanisms that are employed (mutagenesis, recombination, transposition) have been an issue left to the elegant discipline of evolutionary biology. But behind the theory are realities that we have yet to ascertain: How does an evolving cell accommodate its requirements for both conserving its essential functions, while also providing a selective advantage? In this volume, we focus on the evolution of the eukaryotic telomere, the ribo-nuclear protein complex at the end of a linear chromosome. The telomere is an example of a single chromosomal element that must function to maintain genomic stability. The telomeres of all species must provide a means to avoid the attrition from semi-conservative DNA replication and a means of telomere elongation (the telomere replication problem). For example, telomerase is the most well-studied mechanism to circumvent telomere attrition by adding the short repeats that constitutes most telomeres. The telomere must also guard against the multiple activities that can act on an unprotected double strand break requiring a window (or checkpoint) to compensate for telomere sequence loss as well as protection against non-specific processes (the telomere protection problem). This volume describes a range of methodologies including mechanistic studies, phylogenetic comparisons and data-based theoretical approaches to study telomere evolution over a broad spectrum of organisms that includes plants, animals and fungi. In telomeres that are elongated by telomerases, different components have widely different rates of evolution. Telomerases evolved from roots in archaebacteria including splicing factors and LTR-transposition. At the conserved level, the telomere is a rebel among double strand breaks (DSBs) and has altered the function of the highly conserved proteins of the ATM pathway into an elegant means of protecting the chromosome end and maintaining telomere size homeostasis through a competition of positive and negative factors. This homeostasis, coupled with highly conserved capping proteins, is sufficient for protection. However, far more proteins are present at the telomere to provide additional species-specific functions. Do these proteins provide insight into how the cell allows for rapid change without self-destruction?

Genome Stability

Genome Stability
Author: James Haber
Publisher: Garland Science
Total Pages: 416
Release: 2013-12-16
Genre: Science
ISBN: 1317682319

Download Genome Stability Book in PDF, Epub and Kindle

Genome Stability: DNA Repair and Recombination describes the various mechanisms of repairing DNA damage by recombination, most notably the repair of chromosomal breaks. The text presents a definitive history of the evolution of molecular models of DNA repair, emphasizing current research. The book introduces the central players in recombination. An overview of the four major pathways of homologous recombinational repair is followed by a description of the several mechanisms of nonhomologous end-joining. Designed as a textbook for advanced undergraduate and graduate students with a molecular biology and genetics background, researchers and practitioners, especially in cancer biology, will also appreciate the book as a reference.

Telomeres and Telomerase

Telomeres and Telomerase
Author: Predrag Slijepcevic
Publisher: S. Karger AG (Switzerland)
Total Pages: 0
Release: 2008
Genre: Telomerase
ISBN: 9783805590631

Download Telomeres and Telomerase Book in PDF, Epub and Kindle

Telomeres are essential functional elements of eukaryotic chromosomes. Their fundamental biological role as protectors of chromosome stability was identified for the first time in the 1930s by Hermann Muller and Barbara McClintock based on pioneering cytological experiments. Modern molecular research carried out more recently revealed that telomeres and telomerase play important roles in processes such as carcinogenesis and cellular senescence. This special issue presents the most recent developments in this highly active field of research. It is becoming increasingly clear that molecular pathways involved in regulation of telomere length and structure are functionally linked with pathways involved in DNA damage response, cellular stress response, chromatin organization and perhaps even pathways that regulate evolutionary chromosome rearrangements. The above functional link is explored by the leading experts in the field of telomere biology. Cell biologists, molecular biologists, oncologists, gerontologists, and radiobiologists with an interest in the role of telomeres/telomerase will appreciate the up-to-date information in this publication.

Genome Stability

Genome Stability
Author: Igor Kovalchuk
Publisher: Academic Press
Total Pages: 762
Release: 2021-07-17
Genre: Science
ISBN: 0323856802

Download Genome Stability Book in PDF, Epub and Kindle

Genome Stability: From Virus to Human Application, Second Edition, a volume in the Translational Epigenetics series, explores how various species maintain genome stability and genome diversification in response to environmental factors. Here, across thirty-eight chapters, leading researchers provide a deep analysis of genome stability in DNA/RNA viruses, prokaryotes, single cell eukaryotes, lower multicellular eukaryotes, and mammals, examining how epigenetic factors contribute to genome stability and how these species pass memories of encounters to progeny. Topics also include major DNA repair mechanisms, the role of chromatin in genome stability, human diseases associated with genome instability, and genome stability in response to aging. This second edition has been fully revised to address evolving research trends, including CRISPRs/Cas9 genome editing; conventional versus transgenic genome instability; breeding and genetic diseases associated with abnormal DNA repair; RNA and extrachromosomal DNA; cloning, stem cells, and embryo development; programmed genome instability; and conserved and divergent features of repair. This volume is an essential resource for geneticists, epigeneticists, and molecular biologists who are looking to gain a deeper understanding of this rapidly expanding field, and can also be of great use to advanced students who are looking to gain additional expertise in genome stability. A deep analysis of genome stability research from various kingdoms, including epigenetics and transgenerational effects Provides comprehensive coverage of mechanisms utilized by different organisms to maintain genomic stability Contains applications of genome instability research and outcomes for human disease Features all-new chapters on evolving areas of genome stability research, including CRISPRs/Cas9 genome editing, RNA and extrachromosomal DNA, programmed genome instability, and conserved and divergent features of repair

Maintenance of Genome Integrity: DNA Damage Sensing, Signaling, Repair and Replication in Plants

Maintenance of Genome Integrity: DNA Damage Sensing, Signaling, Repair and Replication in Plants
Author:
Publisher:
Total Pages: 0
Release: 2016
Genre:
ISBN:

Download Maintenance of Genome Integrity: DNA Damage Sensing, Signaling, Repair and Replication in Plants Book in PDF, Epub and Kindle

Environmental stresses and metabolic by-products can severely affect the integrity of genetic information by inducing DNA damage and impairing genome stability. As a consequence, plant growth and productivity are irreversibly compromised. To overcome genotoxic injury, plants have evolved complex strategies relying on a highly efficient repair machinery that responds to sophisticated damage perception/signaling networks. The DNA damage signaling network contains several key components: DNA damage sensors, signal transducers, mediators, and effectors. Most of these components are common to other eukaryotes but some features are unique to the plant kingdom. ATM and ATR are well-conserved members of PIKK family, which amplify and transduce signals to downstream effectors. ATM primarily responds to DNA double strand breaks while ATR responds to various forms of DNA damage. The signals from the activated transducer kinases are transmitted to the downstream cell-cycle regulators, such as CHK1, CHK2, and p53 in many eukaryotes. However, plants have no homologue of CHK1, CHK2 nor p53. The finding of Arabidopsis transcription factor SOG1 that seems functionally but not structurally similar to p53 suggests that plants have developed unique cell cycle regulation mechanism. The double strand break repair, recombination repair, postreplication repair, and lesion bypass, have been investigated in several plants. The DNA double strand break, a most critical damage for organisms are repaired non-homologous end joining (NHEJ) or homologous recombination (HR) pathway. Damage on template DNA makes replication stall, which is processed by translesion synthesis (TLS) or error-free postreplication repair (PPR) pathway. Deletion of the error-prone TLS polymerase reduces mutation frequencies, suggesting PPR maintains the stalled replication fork when TLS is not available. Unveiling the regulation networks among these multiple pathways would be the next challenge to be completed. Some intriguing issues have been disclosed such as the cross-talk between DNA repair, senescence and pathogen response and the involvement of non-coding RNAs in global genome stability. Several studies have highlighted the essential contribution of chromatin remodeling in DNA repair. DNA damage sensing, signaling and repair have been investigated in relation to environmental stresses, seed quality issues, mutation breeding in both model and crop plants and all these studies strengthen the idea that components of the plant response to genotoxic stress might represent tools to improve stress tolerance and field performance. This focus issue gives researchers the opportunity to gather and interact by providing Mini-Reviews, Commentaries, Opinions, Original Research and Method articles which describe the most recent advances and future perspectives in the field of DNA damage sensing, signaling and repair in plants. A comprehensive overview of the current progresses dealing with the genotoxic stress response in plants will be provided looking at cellular and molecular level with multidisciplinary approaches. This will hopefully bring together valuable information for both plant biotechnologists and breeders.

The DNA Damage Response: Implications on Cancer Formation and Treatment

The DNA Damage Response: Implications on Cancer Formation and Treatment
Author: Kum Kum Khanna
Publisher: Springer Science & Business Media
Total Pages: 450
Release: 2009-09-18
Genre: Medical
ISBN: 9048125618

Download The DNA Damage Response: Implications on Cancer Formation and Treatment Book in PDF, Epub and Kindle

The ?eld of cellular responses to DNA damage has attained widespread recognition and interest in recent years commensurate with its fundamental role in the ma- tenance of genomic stability. These responses, which are essential to preventing cellular death or malignant transformation, are organized into a sophisticated s- tem designated the “DNA damage response”. This system operates in all living organisms to maintain genomic stability in the face of constant attacks on the DNA from a variety of endogenous by-products of normal metabolism, as well as exogenous agents such as radiation and toxic chemicals in the environment. The response repairs DNA damage via an intricate cellular signal transduction network that coordinates with various processes such as regulation of DNA replication, tr- scriptional responses, and temporary cell cycle arrest to allow the repair to take place. Defects in this system result in severe genetic disorders involving tissue degeneration, sensitivity to speci?c damaging agents, immunode?ciency, genomic instability, cancer predisposition and premature aging. The ?nding that many of the crucial players involved in DNA damage response are structurally and functionally conserved in different species spurred discoveries of new players through similar analyses in yeast and mammals. We now understand the chain of events that leads to instantaneous activation of the massive cellular responses to DNA lesions. This book summarizes several new concepts in this rapidly evolving ?eld, and the advances in our understanding of the complex network of processes that respond to DNA damage.

DNA Replication Challenges

DNA Replication Challenges
Author: Shankar Parajuli
Publisher:
Total Pages: 137
Release: 2017
Genre: Electronic dissertations
ISBN:

Download DNA Replication Challenges Book in PDF, Epub and Kindle

Faithful DNA replication and repair are essential for maintaining genome stability and preventing various diseases including cancer. Both processes are executed by numerous redundant mechanisms to ensure that these processes are uninterrupted even when a primary mechanism fails. Despite this, they are not immune to challenges and failures leading to DNA damage and genome instability. These problems are more evident at the difficult-to-replicate regions of the genome such as the telomeres that cap and protect linear chromosome ends. Additionally, topological structures such as RNA:DNA hybrids, commonly referred to as R loops, can also present severe challenges to the DNA replication and repair machineries. Herein we report the functions of two distinct DNA replication and repair proteins--flap endonuclease 1 (FEN1) and ribonuclease H1 (RNH1)--that preserve genome stability. First, we show that FEN1 limits telomere fragility in leading strand replicated telomeres. This is mediated by its flap endonuclease activity independent of its gap endonuclease activity and C-terminal interactions. We show that the fragility phenotype is increased by RNA polymerase II inhibition and rescued by ectopic RNH1 expression. Because the telomere is transcribed and can form hybrids, these data suggest that the FEN1-mediated telomere fragility depends on RNA:DNA hybrids that accumulate from co-directional replisome-RNAP collision at the leading strand replicated telomere. These findings are the first to assign a leading strand specific function of FEN1, which is a canonical lagging strand protein. Second, we uncover a novel role for human RNH1 in DNA replication in the nucleus. We show that RNH1 depletion results in a global DNA damage response as well as telomere loss phenotype. Because RNH1 resolves RNA:DNA hybrids, we measured those hybrid levels and found that they increase upon RNH1 depletion. Given these hybrids could pose barriers to a moving replication machinery, we interrogated replication efficiency and discovered that RNH1 facilitates the replication fork movement, possibly by clearing hybrids. These data shed light onto the role of RNH1 in global DNA replication. Together, our work underscore the complexity of DNA replication and repair processes and highlight the varied roles that FEN1 and RNH1 play to maintain genome stability.

Telomeres and Telomerase in Cancer

Telomeres and Telomerase in Cancer
Author: Keiko Hiyama
Publisher: Springer Science & Business Media
Total Pages: 375
Release: 2009-03-18
Genre: Medical
ISBN: 1603278796

Download Telomeres and Telomerase in Cancer Book in PDF, Epub and Kindle

Telomerase, an enzyme that maintains telomeres and endows eukaryotic cells with immortality, was first discovered in tetrahymena in 1985. In 1990s, it was proven that this enzyme also plays a key role in the infinite proliferation of human cancer cells. Now telomere and telomerase are widely accepted as important factors involved in cancer biology, and as promising diagnostic tools and therapeutic targets. Recently, role of telomerase in “cancer stem cells” has become another attractive story. Until now, there are several good books on telomere and telomerase focusing on biology in ciliates, yeasts, and mouse or basic sciences in human, providing basic scientists or students with updated knowledge.