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Lawing AM, McCoy M, Reinke BA, Sarkar SK, Smith FA, Wright D. A Framework for Investigating Rules of Life by Establishing Zones of Influence. Integr Comp Biol 2021; 61:2095-2108. [PMID: 34297089 DOI: 10.1093/icb/icab169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/26/2021] [Accepted: 07/20/2021] [Indexed: 12/18/2022] Open
Abstract
The incredible complexity of biological processes across temporal and spatial scales hampers defining common underlying mechanisms driving the patterns of life. However, recent advances in sequencing, big data analysis, machine learning, and molecular dynamics simulation have renewed the hope and urgency of finding potential hidden rules of life. There currently exists no framework to develop such synoptic investigations. Some efforts aim to identify unifying rules of life across hierarchical levels of time, space, and biological organization, but not all phenomena occur across all the levels of these hierarchies. Instead of identifying the same parameters and rules across levels, we posit that each level of a temporal and spatial scale and each level of biological organization has unique parameters and rules that may or may not predict outcomes in neighboring levels. We define this neighborhood, or the set of levels, across which a rule functions as the zone of influence. Here, we introduce the zone of influence framework and explain using three examples: (Smocovitis, 1992) randomness in biology, where we use a Poisson process to describe processes from protein dynamics to DNA mutations to gene expressions, (Leroi, 2014) island biogeography, and (Gropp, 2016) animal coloration. The zone of influence framework may enable researchers to identify which levels are worth investigating for a particular phenomenon and reframe the narrative of searching for a unifying rule of life to the investigation of how, when, and where various rules of life operate.
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Affiliation(s)
| | - Michael McCoy
- Department of Biology, East Carolina University, NC, USA
| | - Beth A Reinke
- Department of Biology, Northeastern Illinois University, IL, USA
| | | | - Felisa A Smith
- Department of Biology, University of New Mexico, NM, USA
| | - Derek Wright
- Department of Physics, Colorado School of Mines, CO, USA
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2
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Luo B, Edge AK, Tolg C, Turley EA, Dean CB, Hill KA, Kulperger RJ. Spatial statistical tools for genome-wide mutation cluster detection under a microarray probe sampling system. PLoS One 2018; 13:e0204156. [PMID: 30252889 PMCID: PMC6155535 DOI: 10.1371/journal.pone.0204156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 09/04/2018] [Indexed: 11/30/2022] Open
Abstract
Mutation cluster analysis is critical for understanding certain mutational mechanisms relevant to genetic disease, diversity, and evolution. Yet, whole genome sequencing for detection of mutation clusters is prohibitive with high cost for most organisms and population surveys. Single nucleotide polymorphism (SNP) genotyping arrays, like the Mouse Diversity Genotyping Array, offer an alternative low-cost, screening for mutations at hundreds of thousands of loci across the genome using experimental designs that permit capture of de novo mutations in any tissue. Formal statistical tools for genome-wide detection of mutation clusters under a microarray probe sampling system are yet to be established. A challenge in the development of statistical methods is that microarray detection of mutation clusters is constrained to select SNP loci captured by probes on the array. This paper develops a Monte Carlo framework for cluster testing and assesses test statistics for capturing potential deviations from spatial randomness which are motivated by, and incorporate, the array design. While null distributions of the test statistics are established under spatial randomness via the homogeneous Poisson process, power performance of the test statistics is evaluated under postulated types of Neyman-Scott clustering processes through Monte Carlo simulation. A new statistic is developed and recommended as a screening tool for mutation cluster detection. The statistic is demonstrated to be excellent in terms of its robustness and power performance, and useful for cluster analysis in settings of missing data. The test statistic can also be generalized to any one dimensional system where every site is observed, such as DNA sequencing data. The paper illustrates how the informal graphical tools for detecting clusters may be misleading. The statistic is used for finding clusters of putative SNP differences in a mixture of different mouse genetic backgrounds and clusters of de novo SNP differences arising between tissues with development and carcinogenesis.
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Affiliation(s)
- Bin Luo
- Department of Statistical and Actuarial Sciences, Western University, London, Ontario, Canada
- * E-mail: (BL); (CBD); (KAH); (RJK)
| | - Alanna K. Edge
- Department of Biology, Western University, London, Ontario, Canada
| | - Cornelia Tolg
- London Regional Cancer Program, Lawson Health Research Institute, London, Ontario, Canada
| | - Eva A. Turley
- London Regional Cancer Program, Lawson Health Research Institute, London, Ontario, Canada
| | - C. B. Dean
- Department of Statistics and Actuarial Science, University of Waterloo, Waterloo, Ontario, Canada
- * E-mail: (BL); (CBD); (KAH); (RJK)
| | - Kathleen A. Hill
- Department of Biology, Western University, London, Ontario, Canada
- * E-mail: (BL); (CBD); (KAH); (RJK)
| | - R. J. Kulperger
- Department of Statistical and Actuarial Sciences, Western University, London, Ontario, Canada
- * E-mail: (BL); (CBD); (KAH); (RJK)
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3
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Alexander HK, Mayer SI, Bonhoeffer S. Population Heterogeneity in Mutation Rate Increases the Frequency of Higher-Order Mutants and Reduces Long-Term Mutational Load. Mol Biol Evol 2017; 34:419-436. [PMID: 27836985 PMCID: PMC5850754 DOI: 10.1093/molbev/msw244] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Mutation rate is a crucial evolutionary parameter that has typically been treated as a constant in population genetic analyses. However, the propensity to mutate is likely to vary among co-existing individuals within a population, due to genetic polymorphisms, heterogeneous environmental influences, and random physiological fluctuations. We review the evidence for mutation rate heterogeneity and explore its consequences by extending classic population genetic models to allow an arbitrary distribution of mutation rate among individuals, either with or without inheritance. With this general new framework, we rigorously establish the effects of heterogeneity at various evolutionary timescales. In a single generation, variation of mutation rate about the mean increases the probability of producing zero or many simultaneous mutations on a genome. Over multiple generations of mutation and selection, heterogeneity accelerates the appearance of both deleterious and beneficial multi-point mutants. At mutation-selection balance, higher-order mutant frequencies are likewise boosted, while lower-order mutants exhibit subtler effects; nonetheless, population mean fitness is always enhanced. We quantify the dependencies on moments of the mutation rate distribution and selection coefficients, and clarify the role of mutation rate inheritance. While typical methods of estimating mutation rate will recover only the population mean, analyses assuming mutation rate is fixed to this mean could underestimate the potential for multi-locus adaptation, including medically relevant evolution in pathogenic and cancerous populations. We discuss the potential to empirically parameterize mutation rate distributions, which have to date hardly been quantified.
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Affiliation(s)
- Helen K. Alexander
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Switzerland
| | - Stephanie I. Mayer
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Switzerland
| | - Sebastian Bonhoeffer
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Switzerland
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4
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Abstract
It has been long understood that mutation distribution is not completely random across genomic space and in time. Indeed, recent surprising discoveries identified multiple simultaneous mutations occurring in tiny regions within chromosomes while the rest of the genome remains relatively mutation-free. Mechanistic elucidation of these phenomena, called mutation showers, mutation clusters, or kataegis, in parallel with findings of abundant clustered mutagenesis in cancer genomes, is ongoing. So far, the combination of factors most important for clustered mutagenesis is the induction of DNA lesions within unusually long and persistent single-strand DNA intermediates. In addition to being a fascinating phenomenon, clustered mutagenesis also became an indispensable tool for identifying a previously unrecognized major source of mutation in cancer, APOBEC cytidine deaminases. Future research on clustered mutagenesis may shed light onto important mechanistic details of genome maintenance, with potentially profound implications for human health.
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Affiliation(s)
- Kin Chan
- Mechanisms of Genome Dynamics Group, National Institute of Environmental Health Sciences, Department of Health and Human Services, National Institutes of Health, Durham, North Carolina 27709; ,
| | - Dmitry A Gordenin
- Mechanisms of Genome Dynamics Group, National Institute of Environmental Health Sciences, Department of Health and Human Services, National Institutes of Health, Durham, North Carolina 27709; ,
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5
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Nikitaki Z, Hellweg CE, Georgakilas AG, Ravanat JL. Stress-induced DNA damage biomarkers: applications and limitations. Front Chem 2015; 3:35. [PMID: 26082923 PMCID: PMC4451417 DOI: 10.3389/fchem.2015.00035] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 05/07/2015] [Indexed: 11/13/2022] Open
Abstract
A variety of environmental stresses like chemicals, UV and ionizing radiation and organism's endogenous processes such as replication stress and metabolism can lead to the generation of reactive oxygen and nitrogen species (ROS/RNS) that can attack cellular vital components like DNA, proteins and lipid membranes. Among them, much attention has been focused on DNA since DNA damage plays a role in several biological disorders and aging processes. Thus, DNA damage can be used as a biomarker in a reliable and accurate way to quantify for example radiation exposure and can indicate its possible long term effects and cancer risk. Based on the type of DNA lesions detected one can hypothesize on the most probable mechanisms involved in the formation of these lesions for example in the case of UV and ionizing radiation (e.g., X- or α-, γ-rays, energetic ions, neutrons). In this review we describe the most accepted chemical pathways for DNA damage induction and the different types of DNA lesions, i.e., single, complex DNA lesions etc. that can be used as DNA damage biomarkers. We critically compare DNA damage detection methods and their limitations. In addition, we suggest the use of DNA repair gene products as biomarkes for identification of different types of stresses i.e., radiation, oxidative, or replication stress, based on bioinformatic approaches and meta-analysis of literature data.
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Affiliation(s)
- Zacharenia Nikitaki
- DNA Damage and Repair Laboratory, Physics Department, School of Applied Mathematical and Physical Sciences, National Technical University of Athens Athens, Greece
| | - Christine E Hellweg
- Radiation Biology Department, German Aerospace Center (DLR), Institute of Aerospace Medicine Köln, Germany
| | - Alexandros G Georgakilas
- DNA Damage and Repair Laboratory, Physics Department, School of Applied Mathematical and Physical Sciences, National Technical University of Athens Athens, Greece
| | - Jean-Luc Ravanat
- Laboratoire des Lésions des Acides Nucléiques, Institut des Nanosciences et Cryogénie, Service de Chimie Inorgranique et Biologique, Université Grenoble Alpes Grenoble, France ; CEA, Institut des Nanosciences et Cryogénie, Service de Chimie Inorgranique et Biologique Grenoble, France
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6
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van den Boogaard ML, Lemmers RJFL, Camaño P, van der Vliet PJ, Voermans N, van Engelen BGM, Lopez de Munain A, Tapscott SJ, van der Stoep N, Tawil R, van der Maarel SM. Double SMCHD1 variants in FSHD2: the synergistic effect of two SMCHD1 variants on D4Z4 hypomethylation and disease penetrance in FSHD2. Eur J Hum Genet 2015; 24:78-85. [PMID: 25782668 DOI: 10.1038/ejhg.2015.55] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 02/17/2015] [Accepted: 02/20/2015] [Indexed: 01/03/2023] Open
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) predominantly affects the muscles in the face, trunk and upper extremities and is marked by large clinical variability in disease onset and progression. FSHD is associated with partial chromatin relaxation of the D4Z4 repeat array on chromosome 4 and the somatic expression of the D4Z4 encoded DUX4 gene. The most common form, FSHD1, is caused by a contraction of the D4Z4 repeat array on chromosome 4 to a size of 1-10 units. FSHD2, the less common form of FSHD, is most often caused by heterozygous variants in the chromatin modifier SMCHD1, which is involved in the maintenance of D4Z4 methylation. We identified three families in which the proband carries two potentially damaging SMCHD1 variants. We investigated whether these variants were located in cis or in trans and determined their functional consequences by detailed clinical information and D4Z4 methylation studies. In the first family, both variants in trans were shown to act synergistically on D4Z4 hypomethylation and disease penetrance, in the second family both SMCHD1 function-affecting variants were located in cis while in the third family one of the two variants did not affect function. This study demonstrates that having two SMCHD1 missense variants that affect function is compatible with life in males and females, which is remarkable considering its role in X inactivation in mice. The study also highlights the variability in SMCHD1 variants underlying FSHD2 and the predictive value of D4Z4 methylation analysis in determining the functional consequences of SMCHD1 variants of unknown significance.
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Affiliation(s)
| | - Richard J F L Lemmers
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Pilar Camaño
- Neurosciences, BioDonostia Health Research Institute, Hospital Donostia, San Sebastián, Spain
| | | | - Nicol Voermans
- Department of Neurology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | | | - Adolfo Lopez de Munain
- Neurosciences, BioDonostia Health Research Institute, Hospital Donostia, San Sebastián, Spain
| | - Stephen J Tapscott
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Nienke van der Stoep
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Rabi Tawil
- Department of Neurology, University of Rochester Medical Center, Rochester, MN, USA
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7
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Chen JM, Férec C, Cooper DN. Transient hypermutability, chromothripsis and replication-based mechanisms in the generation of concurrent clustered mutations. Mutat Res 2012; 750:52-9. [PMID: 22100908 DOI: 10.1016/j.mrrev.2011.10.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 10/25/2011] [Accepted: 10/27/2011] [Indexed: 12/21/2022]
Abstract
Clustered mutations may be broadly defined as the presence of two or more mutations within a spatially localized genomic region on a single chromosome. Known instances vary in terms of both the number and type of the component mutations, ranging from two closely spaced point mutations to tens or even hundreds of genomic rearrangements. Although clustered mutations can represent the observable net result of independent lesions sequentially acquired over multiple cell cycles, they can also be generated in a simultaneous or quasi-simultaneous manner within a single cell cycle. This review focuses on those mechanisms known to underlie the latter type. Both gene conversion and transient hypermutability are capable of generating closely spaced multiple mutations. However, a recently described phenomenon in human cancer cells, known as 'chromothripsis', has provided convincing evidence that tens to hundreds of genomic rearrangements can sometimes be generated simultaneously via a single catastrophic event. The distinctive genomic features observed in the derivative chromosomes, together with the highly characteristic junction sequences, point to non-homologous end joining (NHEJ) as being the likely underlying mutational mechanism. By contrast, replication-based mechanisms such as microhomology-mediated break-induced replication (MMBIR) which involves serial replication slippage or serial template switching probably account for those complex genomic rearrangements that comprise multiple duplications and/or triplications.
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Affiliation(s)
- Jian-Min Chen
- Institut National de la Santé et de la Recherche Médicale (INSERM), U613, Brest, France.
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Hashimoto K, Rogozin IB, Panchenko AR. Oncogenic potential is related to activating effect of cancer single and double somatic mutations in receptor tyrosine kinases. Hum Mutat 2012; 33:1566-75. [PMID: 22753356 DOI: 10.1002/humu.22145] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 05/29/2012] [Indexed: 01/16/2023]
Abstract
Aberrant activation of receptor tyrosine kinases (RTKs) is a common feature of many cancer cells. It was previously suggested that the mechanisms of kinase activation in cancer might be linked to transitions between active and inactive states. Here, we estimate the effects of single and double cancer mutations on the stability of active and inactive states of the kinase domains from different RTKs. We show that singleton cancer mutations destabilize active and inactive states; however, inactive states are destabilized more than the active ones, leading to kinase activation. We show that there exists a relationship between the estimate of oncogenic potential of cancer mutation and kinase activation. Namely, more frequent mutations have a higher activating effect, which might allow us to predict the activating effect of the mutations from the mutation spectra. Independent evolutionary analysis of mutation spectra complements this observation and finds the same frequency threshold defining mutation hotspots. We analyze double mutations and report a positive epistasis and additional advantage of doublets with respect to cancer cell fitness. The activation mechanisms of double mutations differ from those of single mutations and double mutation spectrum is found to be dissimilar to the mutation spectrum of singletons.
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Affiliation(s)
- Kosuke Hashimoto
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894, USA
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9
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Chen JM, Férec C, Cooper DN. Gene conversion in human genetic disease. Genes (Basel) 2010; 1:550-63. [PMID: 24710102 PMCID: PMC3966225 DOI: 10.3390/genes1030550] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 11/12/2010] [Accepted: 11/17/2010] [Indexed: 01/01/2023] Open
Abstract
Gene conversion is a specific type of homologous recombination that involves the unidirectional transfer of genetic material from a ‘donor’ sequence to a highly homologous ‘acceptor’. We have recently reviewed the molecular mechanisms underlying gene conversion, explored the key part that this process has played in fashioning extant human genes, and performed a meta-analysis of gene-conversion events known to have caused human genetic disease. Here we shall briefly summarize some of the latest developments in the study of pathogenic gene conversion events, including (i) the emerging idea of minimal efficient sequence homology (MESH) for homologous recombination, (ii) the local DNA sequence features that appear to predispose to gene conversion, (iii) a mechanistic comparison of gene conversion and transient hypermutability, and (iv) recently reported examples of pathogenic gene conversion events.
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Affiliation(s)
- Jian-Min Chen
- Institut National de la Santé et de la Recherche Médicale (INSERM), U613, Brest, France.
| | - Claude Férec
- Institut National de la Santé et de la Recherche Médicale (INSERM), U613, Brest, France.
| | - David N Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
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10
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HO* radicals induce an unexpected high proportion of tandem base lesions refractory to repair by DNA glycosylases. Proc Natl Acad Sci U S A 2010; 107:5528-33. [PMID: 20212167 DOI: 10.1073/pnas.1000193107] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Reaction of HO(*) radicals with double-stranded calf thymus DNA produces high levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) and, to a minor extent, 8-oxo-7,8-dihydro-2'-deoxyadenosine (8-oxodAdo). Formation of the hydroxylated purine lesions is explained by addition of HO(*) to the C8 position of the purine moiety. It has been reported that tandem lesions containing a formylamine residue neighboring 8-oxodGuo could be produced through addition of a transiently generated pyrimidine peroxyl radical onto the C8 of an adjacent purine base. Formation of such tandem lesions accounted for approximately 10% of the total 8-oxodGuo. In the present work we show that addition of HO(*) onto the C8 of purine accounts for only approximately 5% of the generated 8-oxodGuo. About 50% of the 8-hydroxylated purine lesions, including 8-oxodGuo and 8-oxodAdo, are involved in tandem damage and are produced by peroxyl addition onto the C8 of a vicinal purine base. In addition, the remaining 45% of the 8-oxodGuo are produced by an electron transfer reaction, providing an explanation for the higher yield of formation of 8-oxodGuo compared to 8-oxodAdo. Interestingly, we show that >40% of the 8-oxodGuo involved in tandem lesions is refractory to excision by DNA glycosylases. Altogether our results demonstrate that, subsequently to a single oxidation event, peroxidation reactions significantly increase the yield of formation of hydroxylated purine modifications, generating a high proportion of tandem lesions partly refractory to base excision repair.
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11
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Chen JM, Férec C, Cooper DN. Closely spaced multiple mutations as potential signatures of transient hypermutability in human genes. Hum Mutat 2009; 30:1435-48. [PMID: 19685533 DOI: 10.1002/humu.21088] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Data from diverse organisms suggests that transient hypermutability is a general mutational mechanism with the potential to generate multiple synchronous mutations, a phenomenon probably best exemplified by closely spaced multiple mutations (CSMMs). Here we have attempted to extend the concept of transient hypermutability from somatic cells to the germline, using human inherited disease-causing multiple mutations as a model system. Employing stringent criteria for data inclusion, we have retrospectively identified numerous potential examples of pathogenic CSMMs that exhibit marked similarities to the CSMMs reported in other systems. These examples include (1) eight multiple mutations, each comprising three or more components within a sequence tract of <100 bp; (2) three possible instances of "mutation showers"; and (3) numerous highly informative "homocoordinate" mutations. Using the proportion of CpG substitution as a crude indicator of the relative likelihood of transient hypermutability, we present evidence to suggest that CSMMs comprising at least one pair of mutations separated by < or =100 bp may constitute signatures of transient hypermutability in human genes. Although this analysis extends the generality of the concept of transient hypermutability and provides new insights into what may be considered a novel mechanism of mutagenesis underlying human inherited disease, it has raised serious concerns regarding current practices in mutation screening.
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Affiliation(s)
- Jian-Min Chen
- Institut National de la Santé et de la Recherche Médicale, U613, Brest, France.
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12
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Abstract
The rate of mutation refers to the probability that a unit length of DNA (generally a base pair) mutates with time. Fluctuation analysis or mutant accumulation assays applied to phenotypic changes measure mutation rates of cells. However, only a few phenotypic changes indicative of mutations are known thus limiting the analysis to those rare genes. Direct sequencing overcomes the limitations imposed by phenotypic analysis but is limited by the extensive number of clones or cells that have to be analyzed in fluctuation or mutant accumulation assays. We propose a strategy to determine the rate of mutation of a gene by limited direct sequencing of a few single cells of a defined lineage. To accomplish this, we determined the average number of mutations per position in each DNA length sequenced from the proportion of the non-mutated positions, according to the Poisson process and/or the Taylor series. Measuring the rate of mutation by direct sequencing of genes does not require ascertaining a phenotype and can be applied to any area of the genome in a cell. The approach avoids fluctuation errors.
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Affiliation(s)
- Samuel J Balin
- Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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13
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Crabbe RA, Prtenjaca A, Tarnowski HE, Hill KA. A novel germline mutation in Big Blue mice. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2009; 50:114-120. [PMID: 19107908 DOI: 10.1002/em.20442] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The Big Blue lacI mutation detection assay is well validated and has permitted detailed analysis of spontaneous mutations in individual tissues over the lifespan of the mouse. In a recent assay of spontaneous mutations, a novel lacI mutation (C354T) recurred in six of seven mutants with a second mutation. The frequency of spontaneous doublets (mutants with two nontandem mutations) was elevated 2.7-fold over that previously reported (Hill KA et al., [2004b]: Mutat Res 554:223-240) for normal tissues (6.3 x 10(-7) herein vs. 2.36 x 10(-7)). The average spacing between mutations in the doublets (237 bp) was greater than previously reported for spontaneous doublets. The frequency of C354T as a "hitchhiker" mutation in doublets was consistent with a germline mutation in one of 38 mutation targets in the Big Blue mouse genome. C354T is a missense mutation at a CpG dinucleotide producing a conservative amino acid change (Ala109Val) and a very light blue mutant phenotype. Mutant phenotypes of doublets with C354T were typical of the second mutation. C354T was observed in mutants from five tissues of five Big Blue mice. A bidirectional-PCR amplification of specific alleles (Bi-PASA) assay detected C354T in genomic DNA from multiple tissues of five Big Blue mice. These observations are consistent with a novel lacI C354T germline mutation in Big Blue mice that introduces a significant artifact in the analysis of spontaneous mutations. This finding reiterates the importance of identifying all mutations and examining new mutations in the context of our increasingly detailed knowledge of features of spontaneous murine mutations.
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Affiliation(s)
- Rory A Crabbe
- Department of Biology, The University of Western Ontario, London, Ontario, Canada
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14
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Chen Z, Feng J, Buzin CH, Sommer SS. Epidemiology of doublet/multiplet mutations in lung cancers: evidence that a subset arises by chronocoordinate events. PLoS One 2008; 3:e3714. [PMID: 19005564 PMCID: PMC2579325 DOI: 10.1371/journal.pone.0003714] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 10/10/2008] [Indexed: 01/01/2023] Open
Abstract
Background Evidence strongly suggests that spontaneous doublet mutations in normal mouse tissues generally arise from chronocoordinate events. These chronocoordinate mutations sometimes reflect “mutation showers”, which are multiple chronocoordinate mutations spanning many kilobases. However, little is known about mutagenesis of doublet and multiplet mutations (domuplets) in human cancer. Lung cancer accounts for about 25% of all cancer deaths. Herein, we analyze the epidemiology of domuplets in the EGFR and TP53 genes in lung cancer. The EGFR gene is an oncogene in which doublets are generally driver plus driver mutations, while the TP53 gene is a tumor suppressor gene with a more typical situation in which doublets derive from a driver and passenger mutation. Methodology/Principal Findings EGFR mutations identified by sequencing were collected from 66 published papers and our updated EGFR mutation database (www.egfr.org). TP53 mutations were collected from IARC version 12 (www-p53.iarc.fr). For EGFR and TP53 doublets, no clearly significant differences in race, ethnicity, gender and smoking status were observed. Doublets in the EGFR and TP53 genes in human lung cancer are elevated about eight- and three-fold, respectively, relative to spontaneous doublets in mouse (6% and 2.3% versus 0.7%). Conclusions/Significance Although no one characteristic is definitive, the aggregate properties of doublet and multiplet mutations in lung cancer are consistent with a subset derived from chronocoordinate events in the EGFR gene: i) the eight frameshift doublets (present in 0.5% of all patients with EGFR mutations) are clustered and produce a net in-frame change; ii) about 32% of doublets are very closely spaced (≤30 nt); and iii) multiplets contain two or more closely spaced mutations. TP53 mutations in lung cancer are very closely spaced (≤30 nt) in 33% of doublets, and multiplets generally contain two or more very closely spaced mutations. Work in model systems is necessary to confirm the significance of chronocoordinate events in lung and other cancers.
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Affiliation(s)
- Zhenbin Chen
- Department of Molecular Genetics, City of Hope National Medical Center, Duarte, California, United States of America
| | - Jinong Feng
- Department of Molecular Genetics, City of Hope National Medical Center, Duarte, California, United States of America
| | - Carolyn H. Buzin
- Department of Molecular Genetics, City of Hope National Medical Center, Duarte, California, United States of America
| | - Steve S. Sommer
- Department of Molecular Genetics, City of Hope National Medical Center, Duarte, California, United States of America
- * E-mail:
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15
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Chen Z, Feng J, Saldivar JS, Gu D, Bockholt A, Sommer SS. EGFR somatic doublets in lung cancer are frequent and generally arise from a pair of driver mutations uncommonly seen as singlet mutations: one-third of doublets occur at five pairs of amino acids. Oncogene 2008; 27:4336-43. [PMID: 18372921 DOI: 10.1038/onc.2008.71] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Doublet mutations in cancer are not well studied. We find that allelic somatic doublet mutations are present at high frequency in the epidermal growth factor receptor (EGFR) tyrosine kinase (TK) domain in lung cancers. When doublets from the literature are added, a total of 96 doublets are available for analysis. The frequency of doublets overall is 6%, which is sevenfold greater than that observed in normal tissue in mouse. All characterized doublets are allelic, and silent mutations occur rarely. About half of all doublets contain one or two of 12 distinct missense mutations at five amino acids: E709, G719, S768, T790 and L861. The mutations at these five amino acids are seldom reported as singlets. Moreover, when the common L858 target is included, more than one-third of EGFR doublets are one of five specific missense pairs: G719/E709, G719/S768, G719/L861, L858/E709 and L858/T790. Structure suggests function: The data imply that most EGFR doublets are NOT consistent with a 'driver and passenger' mutation mechanism. EGFR doublets are highly skewed relative to singlets, consistent with functional selection of two individually suboptimal mutations that, in combination, have enhanced oncogenic potential.
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Affiliation(s)
- Z Chen
- Department of Molecular Genetics, City of Hope National Medical Center, Duarte, CA 91010-3000, USA
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16
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Abstract
It has recently become clear that the classical notion of the random nature of mutation does not hold for the distribution of mutations among genes: most collections of mutants contain more isolates with two or more mutations than predicted by the mutant frequency on the assumption of a random distribution of mutations. Excesses of multiples are seen in a wide range of organisms, including riboviruses, DNA viruses, prokaryotes, yeasts, and higher eukaryotic cell lines and tissues. In addition, such excesses are produced by DNA polymerases in vitro. These "multiples" appear to be generated by transient, localized hypermutation rather than by heritable mutator mutations. The components of multiples are sometimes scattered at random and sometimes display an excess of smaller distances between mutations. As yet, almost nothing is known about the mechanisms that generate multiples, but such mutations have the capacity to accelerate those evolutionary pathways that require multiple mutations where the individual mutations are neutral or deleterious. Examples that impinge on human health may include carcinogenesis and the adaptation of microbial pathogens as they move between individual hosts.
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Affiliation(s)
- John W Drake
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709-2233, USA.
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17
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Gu D, Scaringe WA, Li K, Saldivar JS, Hill KA, Chen Z, Gonzalez KD, Sommer SS. Database of somatic mutations in EGFR with analyses revealing indel hotspots but no smoking-associated signature. Hum Mutat 2007; 28:760-70. [PMID: 17429853 DOI: 10.1002/humu.20512] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We created an Epidermal Growth Factor Receptor (EGFR) Mutation Database (http://www.cityofhope.org/cmdl/egfr_db) that curates a convenient compilation of somatic EGFR mutations in non-small-cell lung cancer (NSCLC) and associated epidemiological and methodological data, including response to the tyrosine kinase inhibitors Gefitinib and Erlotinib. Herein, we analyze 809 mutations collected from 26 publications. Four super hotspots account for 70% of reported mutations while two-thirds of 131 unique mutations have been reported only once and account for only 11% of reported mutations. Consistent with strong biological selection for gain of function, the reported mutations are virtually all missense substitutions or in-frame microdeletions, microinsertions, or microindels (colocalized insertion and deletion with a net gain or loss of 1-50 nucleotides). Microdeletions and microindels are common in a region of exon 19. Microindels, which account for 8% of mutations, have smaller inserted sequences (95% are 1 to 5 bp) and are elevated 16-fold relative to mouse somatic microindels and to human germline microindels. Microdeletions/microindels are significantly more frequent in responders to Gefitinib or Erlotinib (P = 0.003). In addition, EGFR mutations in smokers do not carry signatures of mutagens in cigarette smoke. Otherwise, the mutation pattern does not differ significantly with respect to gender, age, or tumor histology. The EGFR Mutation Database is a central resource of EGFR sequence variant data for clinicians, geneticists, and other researchers. Authors are encouraged to submit new publications with EGFR sequence variants to be included in the database or to provide direct submissions via The WayStation submission and publication process (http://www.centralmutations.org).
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Affiliation(s)
- Dongqing Gu
- Clinical Molecular Diagnostic Laboratory (CMDL), Department of Molecular Diagnosis, City of Hope National Medical Center, City of Hope, Duarte, California 91010-0269, USA
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18
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Wang J, Gonzalez KD, Scaringe WA, Tsai K, Liu N, Gu D, Li W, Hill KA, Sommer SS. Evidence for mutation showers. Proc Natl Acad Sci U S A 2007; 104:8403-8. [PMID: 17485671 PMCID: PMC1895962 DOI: 10.1073/pnas.0610902104] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mutants in the Big Blue transgenic mouse system show spontaneous clustered multiple mutations with unexpectedly high frequency, consistent with chronocoordinate events. We tested the prediction that the multiple mutations seen within the lacI mutation target sometimes occur in the context of chronocoordinate multiple mutations spanning multiple kilobases (mutation showers). Additional sequencing of mutants was performed in regions immediately flanking the lacI region (total of 10.7 kb). Nineteen additional mutations were found outside the lacI region ("ectomutations") from 10 mutants containing two or more lacI mutations, whereas only one ectomutation was found in 130 mutants with a single mutation (P < 0.0001). The mutation showers had an average of approximately one mutation per 3 kb. Four mutants showed closely spaced double mutations in the new sequence, and analysis of the spacing between these mutations revealed significant clustering (P = 0.0098). To determine the extent of the mutation showers, regions (8.5 kb total) remote from the lacI region (approximately 16-17 kb away) were sequenced. Only two additional ectomutations were found in these remote regions, consistent with mutation showers that generally do not extend more than approximately 30 kb. We conclude that mutation showers exist and that they constitute at least 0.2% and possibly 1% or more of mutational events observed in this system. The existence of mutation showers has implications for oncogenesis and evolution, raising the possibilities of "cancer in an instant" and "introns as sponges to reduce the deleterious impact of mutation showers."
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Affiliation(s)
| | | | - William A. Scaringe
- *Department of Molecular Genetics and
- Bioinformatics Group, Department of Molecular Genetics, City of Hope National Medical Center, Duarte, CA 91010; and
| | | | - Ning Liu
- *Department of Molecular Genetics and
| | - Dongqing Gu
- *Department of Molecular Genetics and
- Bioinformatics Group, Department of Molecular Genetics, City of Hope National Medical Center, Duarte, CA 91010; and
| | - Wenyan Li
- *Department of Molecular Genetics and
| | - Kathleen A. Hill
- *Department of Molecular Genetics and
- Department of Biology, University of Western Ontario, London, ON, CanadaN6A 5B7
| | - Steve S. Sommer
- *Department of Molecular Genetics and
- To whom correspondence should be addressed at:
Beckman Research Institute/City of Hope National Medical Center, 1500 East Duarte Road, Duarte, CA 91010-0269. E-mail:
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19
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Gonzalez KD, Hill KA, Li K, Li W, Scaringe WA, Wang JC, Gu D, Sommer SS. Somatic microindels: analysis in mouse soma and comparison with the human germline. Hum Mutat 2007; 28:69-80. [PMID: 16977595 DOI: 10.1002/humu.20416] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Microindels, defined as mutations that result in a colocalized microinsertion and microdeletion with a net gain or loss of between 1 and 50 nucleotides, may be an important contributor to cancer. We report the first comprehensive analysis of somatic microindels. Our large database of mutations in the lacI transgene of Big Blue((R)) mice contains 0.5% microindels, 2.8% pure microinsertions, and 11.5% pure microdeletions. There appears to be no age, gender, or tissue-type specificity in the frequency of microindels. Of the independent somatic mutations that result in a net in-frame insertion or deletion, microindels are responsible for 13% of protein expansions and 6% of protein contractions. These in-frame microindels may play a crucial role in oncogenesis and evolution via "protein tinkering" (i.e., modest expansion or contraction of proteins). Four characteristics suggest that microindels are caused by unique mechanisms, not just simple combinations of the same mechanisms that cause pure microinsertions and pure microdeletions. First, microinsertions and microdeletions commonly occur at hotspots, but none of the 30 microindels are recurrent. Second, the sizes of the deletions and insertions in microindels are larger and more varied than in pure microdeletions and pure microinsertions. Third, microinsertions overwhelmingly repeat the adjacent base (97%) while the insertions in microindels do so only infrequently (17%). Fourth, analysis of the sequence contexts of microindels is consistent with unique mechanisms including recruitment of translesion DNA synthesis polymerases. The mouse somatic microindels have characteristics similar to those of human germline microindels, consistent with similar causative mechanisms in mouse and human, and in soma and germline.
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Affiliation(s)
- Kelly D Gonzalez
- Department of Molecular Genetics, City of Hope National Medical Center, Duarte, California
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20
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Hill KA, Gonzalez KD, Scaringe WA, Wang JC, Sommer SS. Preferential occurrence of 1-2 microindels. Hum Mutat 2006; 27:55-61. [PMID: 16281281 DOI: 10.1002/humu.20260] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microindels are unique, infrequent mutations that result in inserted and deleted sequences of different sizes (between one and 50 nucleotides) at the same nucleotide position. Little is known about the mutational mechanisms that are responsible for these mutations. From our database of 6,016 independent somatic mutational events in the lacI gene in Big Blue mice, we assembled the 30 microindels (0.5%) for analysis. Microindels with one nucleotide inserted and two nucleotides deleted (1-2 microindels) accounted for seven (23%) of the microindels observed, with the remaining microindels distributed among 21 other combinations of insertion and deletion sizes. A preferential occurrence of 1-2 microindels (20%) was also observed in human germline transmitted mutations in the Human Gene Mutation Database (HGMD). An examination of the sequence flanking the mouse 1-2 microindels did not reveal obvious site specificity or associated secondary structure. A detailed examination of 1-2 microindels did not reveal the features typical of pure microinsertion and microdeletion events, but rather suggested a unique mutational mechanism. The 1 bp insertion in 1-2 microinsertions, and pure 1 bp insertions show distinct features. The mechanism for 1-2 microindels is not obviously a simple combination of pure microinsertion and microdeletion events. The dramatic enhancement of 1-2 microindels requires explanation. We speculate that certain error-prone polymerases may be responsible for the preferential occurrence of 1-2 microindels in both somatic tissues and germ cells. It is estimated that a human adult carries roughly 400 billion somatic 1-2 microindels with the potential to predispose to cancer.
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Affiliation(s)
- Kathleen A Hill
- Department of Molecular Genetics, City of Hope National Medical Center, Duarte, California 91010-0269, USA
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21
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Drake JW, Bebenek A, Kissling GE, Peddada S. Clusters of mutations from transient hypermutability. Proc Natl Acad Sci U S A 2005; 102:12849-54. [PMID: 16118275 PMCID: PMC1200270 DOI: 10.1073/pnas.0503009102] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Indexed: 11/18/2022] Open
Abstract
Collections of mutants usually contain more mutants bearing multiple mutations than expected from the mutant frequency and a random distribution of mutations. This excess is seen in a variety of organisms and also after DNA synthesis in vitro. The excess is unlikely to originate in mutator mutants but rather from transient hypermutability resulting from a perturbation of one of the many transactions that maintain genetic fidelity. The multiple mutations are sometimes clustered and sometimes randomly distributed. We model some spectra as populations comprising a majority with a low mutation frequency and a minority with a high mutation frequency. In the case of mutants produced in vitro by a bacteriophage RB69 mutator DNA polymerase, mutants with two mutations are in approximately 10-fold excess and mutants with three mutations are in even greater excess. However, phenotypically undetectable mutations seen only as hitchhikers with detectable mutations are approximately 5-fold more frequent than mutants bearing detectable mutations, indicating that they arose in a subpopulation with a higher mutation frequency. Excess multiple mutations may contribute critically to carcinogenesis and to adaptive mutation, including the adaptations of pathogens as they move from host to host. In the case of the rapidly mutating riboviruses, the viral population appears to be composed of a majority with a mutation frequency substantially lower than the average and a minority with a huge mutational load.
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Affiliation(s)
- John W Drake
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
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