51
|
Rodrigues JV, Ogbunugafor CB, Hartl DL, Shakhnovich EI. Chimeric dihydrofolate reductases display properties of modularity and biophysical diversity. Protein Sci 2019; 28:1359-1367. [PMID: 31095809 DOI: 10.1002/pro.3646] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 05/13/2019] [Indexed: 01/12/2023]
Abstract
While reverse genetics and functional genomics have long affirmed the role of individual mutations in determining protein function, there have been fewer studies addressing how large-scale changes in protein sequences, such as in entire modular segments, influence protein function and evolution. Given how recombination can reassort protein sequences, these types of changes may play an underappreciated role in how novel protein functions evolve in nature. Such studies could aid our understanding of whether certain organismal phenotypes related to protein function-such as growth in the presence or absence of an antibiotic-are robust with respect to the identity of certain modular segments. In this study, we combine molecular genetics with biochemical and biophysical methods to gain a better understanding of protein modularity in dihydrofolate reductase (DHFR), an enzyme target of antibiotics also widely used as a model for protein evolution. We replace an integral α-helical segment of Escherichia coli DHFR with segments from a number of different organisms (many nonmicrobial) and examine how these chimeric enzymes affect organismal phenotypes (e.g., resistance to an antibiotic) as well as biophysical properties of the enzyme (e.g., thermostability). We find that organismal phenotypes and enzyme properties are highly sensitive to the identity of DHFR modules, and that this chimeric approach can create enzymes with diverse biophysical characteristics.
Collapse
Affiliation(s)
- João V Rodrigues
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts
| | - C Brandon Ogbunugafor
- Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island
| | - Daniel L Hartl
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts
| | - Eugene I Shakhnovich
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts
| |
Collapse
|
52
|
Domingo J, Baeza-Centurion P, Lehner B. The Causes and Consequences of Genetic Interactions (Epistasis). Annu Rev Genomics Hum Genet 2019; 20:433-460. [PMID: 31082279 DOI: 10.1146/annurev-genom-083118-014857] [Citation(s) in RCA: 124] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The same mutation can have different effects in different individuals. One important reason for this is that the outcome of a mutation can depend on the genetic context in which it occurs. This dependency is known as epistasis. In recent years, there has been a concerted effort to quantify the extent of pairwise and higher-order genetic interactions between mutations through deep mutagenesis of proteins and RNAs. This research has revealed two major components of epistasis: nonspecific genetic interactions caused by nonlinearities in genotype-to-phenotype maps, and specific interactions between particular mutations. Here, we provide an overview of our current understanding of the mechanisms causing epistasis at the molecular level, the consequences of genetic interactions for evolution and genetic prediction, and the applications of epistasis for understanding biology and determining macromolecular structures.
Collapse
Affiliation(s)
- Júlia Domingo
- Systems Biology Program, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, 08003 Barcelona, Spain; , ,
| | - Pablo Baeza-Centurion
- Systems Biology Program, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, 08003 Barcelona, Spain; , ,
| | - Ben Lehner
- Systems Biology Program, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, 08003 Barcelona, Spain; , , .,Universitat Pompeu Fabra, 08003 Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
| |
Collapse
|
53
|
Soyk S, Lemmon ZH, Sedlazeck FJ, Jiménez-Gómez JM, Alonge M, Hutton SF, Van Eck J, Schatz MC, Lippman ZB. Duplication of a domestication locus neutralized a cryptic variant that caused a breeding barrier in tomato. NATURE PLANTS 2019; 5:471-479. [PMID: 31061537 DOI: 10.1038/s41477-019-0422-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 04/02/2019] [Indexed: 06/09/2023]
Abstract
Genome editing technologies are being widely adopted in plant breeding1. However, a looming challenge of engineering desirable genetic variation in diverse genotypes is poor predictability of phenotypic outcomes due to unforeseen interactions with pre-existing cryptic mutations2-4. In tomato, breeding with a classical MADS-box gene mutation that improves harvesting by eliminating fruit stem abscission frequently results in excessive inflorescence branching, flowering and reduced fertility due to interaction with a cryptic variant that causes partial mis-splicing in a homologous gene5-8. Here, we show that a recently evolved tandem duplication carrying the second-site variant achieves a threshold of functional transcripts to suppress branching, enabling breeders to neutralize negative epistasis on yield. By dissecting the dosage mechanisms by which this structural variant restored normal flowering and fertility, we devised strategies that use CRISPR-Cas9 genome editing to predictably improve harvesting. Our findings highlight the under-appreciated impact of epistasis in targeted trait breeding and underscore the need for a deeper characterization of cryptic variation to enable the full potential of genome editing in agriculture.
Collapse
Affiliation(s)
- Sebastian Soyk
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA.
| | | | - Fritz J Sedlazeck
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
| | - José M Jiménez-Gómez
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Michael Alonge
- Department of Computer Science, Johns Hopkins University, Baltimore, MD, USA
| | - Samuel F Hutton
- Horticultural Sciences Department, University of Florida, Wimauma, FL, USA
| | - Joyce Van Eck
- The Boyce Thompson Institute, Ithaca, NY, USA
- Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Michael C Schatz
- Department of Computer Science, Johns Hopkins University, Baltimore, MD, USA
- Department of Oncologye, Johns Hopkins Medicine, Baltimore, MD, USA
| | - Zachary B Lippman
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA.
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA.
| |
Collapse
|
54
|
Lauschke VM, Zhou Y, Ingelman-Sundberg M. Novel genetic and epigenetic factors of importance for inter-individual differences in drug disposition, response and toxicity. Pharmacol Ther 2019; 197:122-152. [PMID: 30677473 PMCID: PMC6527860 DOI: 10.1016/j.pharmthera.2019.01.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Individuals differ substantially in their response to pharmacological treatment. Personalized medicine aspires to embrace these inter-individual differences and customize therapy by taking a wealth of patient-specific data into account. Pharmacogenomic constitutes a cornerstone of personalized medicine that provides therapeutic guidance based on the genomic profile of a given patient. Pharmacogenomics already has applications in the clinics, particularly in oncology, whereas future development in this area is needed in order to establish pharmacogenomic biomarkers as useful clinical tools. In this review we present an updated overview of current and emerging pharmacogenomic biomarkers in different therapeutic areas and critically discuss their potential to transform clinical care. Furthermore, we discuss opportunities of technological, methodological and institutional advances to improve biomarker discovery. We also summarize recent progress in our understanding of epigenetic effects on drug disposition and response, including a discussion of the only few pharmacogenomic biomarkers implemented into routine care. We anticipate, in part due to exciting rapid developments in Next Generation Sequencing technologies, machine learning methods and national biobanks, that the field will make great advances in the upcoming years towards unlocking the full potential of genomic data.
Collapse
Affiliation(s)
- Volker M Lauschke
- Department of Physiology and Pharmacology, Section of Pharmacogenetics, Biomedicum 5B, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Yitian Zhou
- Department of Physiology and Pharmacology, Section of Pharmacogenetics, Biomedicum 5B, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Magnus Ingelman-Sundberg
- Department of Physiology and Pharmacology, Section of Pharmacogenetics, Biomedicum 5B, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
| |
Collapse
|
55
|
Proteostasis Environment Shapes Higher-Order Epistasis Operating on Antibiotic Resistance. Genetics 2019; 212:565-575. [PMID: 31015194 PMCID: PMC6553834 DOI: 10.1534/genetics.119.302138] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 04/19/2019] [Indexed: 11/18/2022] Open
Abstract
Recent studies have affirmed that higher-order epistasis is ubiquitous and can have large effects on complex traits. Yet, we lack frameworks for understanding how epistatic interactions are influenced by central features of cell physiology. In this study, we assess how protein quality control machinery-a critical component of cell physiology-affects epistasis for different traits related to bacterial resistance to antibiotics. Specifically, we disentangle the interactions between different protein quality control genetic backgrounds and two sets of mutations: (i) SNPs associated with resistance to antibiotics in an essential bacterial enzyme (dihydrofolate reductase, or DHFR) and (ii) differing DHFR bacterial species-specific amino acid background sequences (Escherichia coli, Listeria grayi, and Chlamydia muridarum). In doing so, we improve on generic observations that epistasis is widespread by discussing how patterns of epistasis can be partly explained by specific interactions between mutations in an essential enzyme and genes associated with the proteostasis environment. These findings speak to the role of environmental and genotypic context in modulating higher-order epistasis, with direct implications for evolutionary theory, genetic modification technology, and efforts to manage antimicrobial resistance.
Collapse
|
56
|
Lee LYH, Loscalzo J. Network Medicine in Pathobiology. THE AMERICAN JOURNAL OF PATHOLOGY 2019; 189:1311-1326. [PMID: 31014954 DOI: 10.1016/j.ajpath.2019.03.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 03/05/2019] [Indexed: 12/11/2022]
Abstract
The past decade has witnessed exponential growth in the generation of high-throughput human data across almost all known dimensions of biological systems. The discipline of network medicine has rapidly evolved in parallel, providing an unbiased, comprehensive biological framework through which to interrogate and integrate systematically these large-scale, multi-omic data to enhance our understanding of disease mechanisms and to design drugs that reflect a deep knowledge of molecular pathobiology. In this review, we discuss the key principles of network medicine and the human disease network and explore the latest applications of network medicine in this multi-omic era. We also highlight the current conceptual and technological challenges, which serve as exciting opportunities by which to improve and expand the network-based applications beyond the artificial boundaries of the current state of human pathobiology.
Collapse
Affiliation(s)
| | - Joseph Loscalzo
- Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
| |
Collapse
|
57
|
Santangelo JS, Johnson MTJ, Ness RW. Modern spandrels: the roles of genetic drift, gene flow and natural selection in the evolution of parallel clines. Proc Biol Sci 2019; 285:rspb.2018.0230. [PMID: 29743253 DOI: 10.1098/rspb.2018.0230] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 04/12/2018] [Indexed: 11/12/2022] Open
Abstract
Urban environments offer the opportunity to study the role of adaptive and non-adaptive evolutionary processes on an unprecedented scale. While the presence of parallel clines in heritable phenotypic traits is often considered strong evidence for the role of natural selection, non-adaptive evolutionary processes can also generate clines, and this may be more likely when traits have a non-additive genetic basis due to epistasis. In this paper, we use spatially explicit simulations modelled according to the cyanogenesis (hydrogen cyanide, HCN) polymorphism in white clover (Trifolium repens) to examine the formation of phenotypic clines along urbanization gradients under varying levels of drift, gene flow and selection. HCN results from an epistatic interaction between two Mendelian-inherited loci. Our results demonstrate that the genetic architecture of this trait makes natural populations susceptible to decreases in HCN frequencies via drift. Gradients in the strength of drift across a landscape resulted in phenotypic clines with lower frequencies of HCN in strongly drifting populations, giving the misleading appearance of deterministic adaptive changes in the phenotype. Studies of heritable phenotypic change in urban populations should generate null models of phenotypic evolution based on the genetic architecture underlying focal traits prior to invoking selection's role in generating adaptive differentiation.
Collapse
Affiliation(s)
- James S Santangelo
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada L5L 1C6 .,Centre for Urban Environments, University of Toronto Mississauga, Mississauga, Ontario, Canada L5L 1C6.,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Marc T J Johnson
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada L5L 1C6.,Centre for Urban Environments, University of Toronto Mississauga, Mississauga, Ontario, Canada L5L 1C6.,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Rob W Ness
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada L5L 1C6.,Centre for Urban Environments, University of Toronto Mississauga, Mississauga, Ontario, Canada L5L 1C6.,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| |
Collapse
|
58
|
Van Steen K, Moore JH. How to increase our belief in discovered statistical interactions via large-scale association studies? Hum Genet 2019; 138:293-305. [PMID: 30840129 PMCID: PMC6483943 DOI: 10.1007/s00439-019-01987-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 02/20/2019] [Indexed: 12/31/2022]
Abstract
The understanding that differences in biological epistasis may impact disease risk, diagnosis, or disease management stands in wide contrast to the unavailability of widely accepted large-scale epistasis analysis protocols. Several choices in the analysis workflow will impact false-positive and false-negative rates. One of these choices relates to the exploitation of particular modelling or testing strategies. The strengths and limitations of these need to be well understood, as well as the contexts in which these hold. This will contribute to determining the potentially complementary value of epistasis detection workflows and is expected to increase replication success with biological relevance. In this contribution, we take a recently introduced regression-based epistasis detection tool as a leading example to review the key elements that need to be considered to fully appreciate the value of analytical epistasis detection performance assessments. We point out unresolved hurdles and give our perspectives towards overcoming these.
Collapse
Affiliation(s)
- K Van Steen
- WELBIO, GIGA-R Medical Genomics-BIO3, University of Liège, Liege, Belgium.
- Department of Human Genetics, University of Leuven, Leuven, Belgium.
| | - J H Moore
- Institute for Biomedical Informatics, University of Pennsylvania, Philadelphia, USA
| |
Collapse
|
59
|
Westhues M, Heuer C, Thaller G, Fernando R, Melchinger AE. Efficient genetic value prediction using incomplete omics data. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2019; 132:1211-1222. [PMID: 30656353 DOI: 10.1007/s00122-018-03273-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 12/21/2018] [Indexed: 05/05/2023]
Abstract
Covering a subset of individuals with a quantitative predictor, while imputing records for all others using pedigree or genomic data, could improve the precision of predictions while controlling for costs. Predicting genetic values with high accuracy is pivotal for effective candidate selection in animal and plant breeding. Novel 'omics'-based predictors have been shown to improve upon established genome-based predictions of important complex traits but require laborious and expensive assays. As a consequence, there are various datasets with full genetic marker coverage of all studied individuals but incomplete coverage with other 'omics' data. In animal breeding, single-step prediction was introduced to efficiently combine pedigree information, collected on a large number of animals, with genomic information, collected on a smaller subset of animals, for breeding value estimation without bias. Using two maize datasets of inbred lines and hybrids, we show that the single-step framework facilitates imputing transcriptomic data, boosting forecasts when their predictive ability exceeds that of pedigree or genomic data. Our results suggest that covering only a subset of inbred lines with 'omics' predictors and imputing all others using pedigree or genomic data could enable breeders to improve trait predictions while keeping costs under control. Employing 'omics' predictors could particularly improve candidate selection in hybrid breeding because the success of forecasts is a strongly convex function of predictive ability.
Collapse
Affiliation(s)
- Matthias Westhues
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70599, Stuttgart, Germany
| | - Claas Heuer
- Institute of Animal Breeding and Husbandry, Christian-Albrechts-University Kiel, 24098, Kiel, Germany
- Inguran, LLC dba STGenetics, 22575 SH6 South, Navasota, TX, 77868, USA
| | - Georg Thaller
- Institute of Animal Breeding and Husbandry, Christian-Albrechts-University Kiel, 24098, Kiel, Germany
| | - Rohan Fernando
- Department of Animal Science, Iowa State University, Ames, IA, 50011, USA
| | - Albrecht E Melchinger
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70599, Stuttgart, Germany.
| |
Collapse
|
60
|
Abstract
Genetic background impacts the phenotypic outcome of a mutation in different individuals; however, the underlying molecular mechanisms are often unclear. We characterized genes exhibiting conditional essentiality when mutated in two genetically distinct yeast strains. Hybrid crosses and whole-genome sequencing revealed that conditional essentiality can be associated with nonchromosomal elements or a single-modifier locus, but most involve a complex set of modifier loci. Detailed analysis of the cysteine biosynthesis pathway showed that independent, rare, single-gene modifiers, related to both up- and downstream pathway functions, can arise in multiple allelic forms from separate lineages. For several genes, we also resolved complex sets of modifying loci underlying conditional essentiality, revealing specific genetic interactions that drive an individual strain’s background effect. The phenotypic consequence of a given mutation can be influenced by the genetic background. For example, conditional gene essentiality occurs when the loss of function of a gene causes lethality in one genetic background but not another. Between two individual Saccharomyces cerevisiae strains, S288c and Σ1278b, ∼1% of yeast genes were previously identified as “conditional essential.” Here, in addition to confirming that some conditional essential genes are modified by a nonchromosomal element, we show that most cases involve a complex set of genomic modifiers. From tetrad analysis of S288C/Σ1278b hybrid strains and whole-genome sequencing of viable hybrid spore progeny, we identified complex sets of multiple genomic regions underlying conditional essentiality. For a smaller subset of genes, including CYS3 and CYS4, each of which encodes components of the cysteine biosynthesis pathway, we observed a segregation pattern consistent with a single modifier associated with conditional essentiality. In natural yeast isolates, we found that the CYS3/CYS4 conditional essentiality can be caused by variation in two independent modifiers, MET1 and OPT1, each with roles associated with cellular cysteine physiology. Interestingly, the OPT1 allelic variation appears to have arisen independently from separate lineages, with rare allele frequencies below 0.5%. Thus, while conditional gene essentiality is usually driven by genetic interactions associated with complex modifier architectures, our analysis also highlights the role of functionally related, genetically independent, and rare variants.
Collapse
|
61
|
Loesbanluechai D, Kotanan N, de Cozar C, Kochakarn T, Ansbro MR, Chotivanich K, White NJ, Wilairat P, Lee MCS, Gamo FJ, Sanz LM, Chookajorn T, Kümpornsin K. Overexpression of plasmepsin II and plasmepsin III does not directly cause reduction in Plasmodium falciparum sensitivity to artesunate, chloroquine and piperaquine. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2018; 9:16-22. [PMID: 30580023 PMCID: PMC6304341 DOI: 10.1016/j.ijpddr.2018.11.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 11/22/2018] [Accepted: 11/24/2018] [Indexed: 01/31/2023]
Abstract
Artemisinin derivatives and their partner drugs in artemisinin combination therapies (ACTs) have played a pivotal role in global malaria mortality reduction during the last two decades. The loss of artemisinin efficacy due to evolving drug-resistant parasites could become a serious global health threat. Dihydroartemisinin-piperaquine is a well tolerated and generally highly effective ACT. The implementation of a partner drug in ACTs is critical in the control of emerging artemisinin resistance. Even though artemisinin is highly effective in parasite clearance, it is labile in the human body. A partner drug is necessary for killing the remaining parasites when the pulses of artemisinin have ceased. A population of Plasmodium falciparum parasites in Cambodia and adjacent countries has become resistant to piperaquine. Increased copy number of the genes encoding the haemoglobinases Plasmepsin II and Plasmepsin III has been linked with piperaquine resistance by genome-wide association studies and in clinical trials, leading to the use of increased plasmepsin II/plasmepsin III copy number as a molecular marker for piperaquine resistance. Here we demonstrate that overexpression of plasmepsin II and plasmepsin III in the 3D7 genetic background failed to change the susceptibility of P. falciparum to artemisinin, chloroquine and piperaquine by both a standard dose-response analysis and a piperaquine survival assay. Whilst plasmepsin copy number polymorphism is currently implemented as a molecular surveillance resistance marker, further studies to discover the molecular basis of piperaquine resistance and potential epistatic interactions are needed.
Collapse
Affiliation(s)
- Duangkamon Loesbanluechai
- Genomics and Evolutionary Medicine Unit (GEM), Centre of Excellence in Malaria Research, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand; Molecular Medicine Program, Multidisciplinary Unit, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Namfon Kotanan
- Genomics and Evolutionary Medicine Unit (GEM), Centre of Excellence in Malaria Research, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Cristina de Cozar
- Tres Cantos Medicine Development Campus, GlaxoSmithKline, Parque Tecnológico de Madrid, Tres Cantos, 28760, Spain
| | - Theerarat Kochakarn
- Genomics and Evolutionary Medicine Unit (GEM), Centre of Excellence in Malaria Research, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Megan R Ansbro
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA; Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, United Kingdom
| | - Kesinee Chotivanich
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand; Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand; Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, Churchill Hospital, Oxford, OX3 7LJ, United Kingdom
| | - Prapon Wilairat
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Marcus C S Lee
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, United Kingdom
| | - Francisco Javier Gamo
- Tres Cantos Medicine Development Campus, GlaxoSmithKline, Parque Tecnológico de Madrid, Tres Cantos, 28760, Spain
| | - Laura Maria Sanz
- Tres Cantos Medicine Development Campus, GlaxoSmithKline, Parque Tecnológico de Madrid, Tres Cantos, 28760, Spain
| | - Thanat Chookajorn
- Genomics and Evolutionary Medicine Unit (GEM), Centre of Excellence in Malaria Research, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.
| | - Krittikorn Kümpornsin
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, United Kingdom.
| |
Collapse
|
62
|
Campbell RF, McGrath PT, Paaby AB. Analysis of Epistasis in Natural Traits Using Model Organisms. Trends Genet 2018; 34:883-898. [PMID: 30166071 PMCID: PMC6541385 DOI: 10.1016/j.tig.2018.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 06/06/2018] [Accepted: 08/03/2018] [Indexed: 12/16/2022]
Abstract
The ability to detect and understand epistasis in natural populations is important for understanding how biological traits are influenced by genetic variation. However, identification and characterization of epistasis in natural populations remains difficult due to statistical issues that arise as a result of multiple comparisons, and the fact that most genetic variants segregate at low allele frequencies. In this review, we discuss how model organisms may be used to manipulate genotypic combinations to power the detection of epistasis as well as test interactions between specific genes. Findings from a number of species indicate that statistical epistasis is pervasive between natural genetic variants. However, the properties of experimental systems that enable analysis of epistasis also constrain extrapolation of these results back into natural populations.
Collapse
Affiliation(s)
- Richard F Campbell
- Department of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332 USA
| | - Patrick T McGrath
- Department of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332 USA; Department of Physics, Georgia Institute of Technology, Atlanta, GA, 30332 USA.
| | - Annalise B Paaby
- Department of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332 USA
| |
Collapse
|
63
|
Mullis MN, Matsui T, Schell R, Foree R, Ehrenreich IM. The complex underpinnings of genetic background effects. Nat Commun 2018; 9:3548. [PMID: 30224702 PMCID: PMC6141565 DOI: 10.1038/s41467-018-06023-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 08/09/2018] [Indexed: 12/01/2022] Open
Abstract
Genetic interactions between mutations and standing polymorphisms can cause mutations to show distinct phenotypic effects in different individuals. To characterize the genetic architecture of these so-called background effects, we genotype 1411 wild-type and mutant yeast cross progeny and measure their growth in 10 environments. Using these data, we map 1086 interactions between segregating loci and 7 different gene knockouts. Each knockout exhibits between 73 and 543 interactions, with 89% of all interactions involving higher-order epistasis between a knockout and multiple loci. Identified loci interact with as few as one knockout and as many as all seven knockouts. In mutants, loci interacting with fewer and more knockouts tend to show enhanced and reduced phenotypic effects, respectively. Cross–environment analysis reveals that most interactions between the knockouts and segregating loci also involve the environment. These results illustrate the complicated interactions between mutations, standing polymorphisms, and the environment that cause background effects. Mutations often show distinct phenotypic effects across different genetic backgrounds. Here the authors describe the genetic basis of these so-called background effects using data on genotype and growth in 10 environments from 1411 segregants from a cross of two strains of budding yeast.
Collapse
Affiliation(s)
- Martin N Mullis
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089-2910, USA.
| | - Takeshi Matsui
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089-2910, USA.
| | - Rachel Schell
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089-2910, USA
| | - Ryan Foree
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089-2910, USA
| | - Ian M Ehrenreich
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089-2910, USA.
| |
Collapse
|
64
|
On the Relationship Between High-Order Linkage Disequilibrium and Epistasis. G3-GENES GENOMES GENETICS 2018; 8:2817-2824. [PMID: 29945968 PMCID: PMC6071592 DOI: 10.1534/g3.118.200513] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A plausible explanation for statistical epistasis revealed in genome wide association analyses is the presence of high order linkage disequilibrium (LD) between the genotyped markers tested for interactions and unobserved functional polymorphisms. Based on findings in experimental data, it has been suggested that high order LD might be a common explanation for statistical epistasis inferred between local polymorphisms in the same genomic region. Here, we empirically evaluate how prevalent high order LD is between local, as well as distal, polymorphisms in the genome. This could provide insights into whether we should account for this when interpreting results from genome wide scans for statistical epistasis. An extensive and strong genome wide high order LD was revealed between pairs of markers on the high density 250k SNP-chip and individual markers revealed by whole genome sequencing in the Arabidopsis thaliana 1001-genomes collection. The high order LD was found to be more prevalent in smaller populations, but present also in samples including several hundred individuals. An empirical example illustrates that high order LD might be an even greater challenge in cases when the genetic architecture is more complex than the common assumption of bi-allelic loci. The example shows how significant statistical epistasis is detected for a pair of markers in high order LD with a complex multi allelic locus. Overall, our study illustrates the importance of considering also other explanations than functional genetic interactions when genome wide statistical epistasis is detected, in particular when the results are obtained in small populations of inbred individuals.
Collapse
|
65
|
Genetic Network Complexity Shapes Background-Dependent Phenotypic Expression. Trends Genet 2018; 34:578-586. [PMID: 29903533 DOI: 10.1016/j.tig.2018.05.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 05/09/2018] [Accepted: 05/17/2018] [Indexed: 11/22/2022]
Abstract
The phenotypic consequences of a given mutation can vary across individuals. This so-called background effect is widely observed, from mutant fitness of loss-of-function variants in model organisms to variable disease penetrance and expressivity in humans; however, the underlying genetic basis often remains unclear. Taking insights gained from recent large-scale surveys of genetic interaction and suppression analyses in yeast, we propose that the genetic network context for a given mutation may shape its propensity of exhibiting background-dependent phenotypes. We argue that further efforts in systematically mapping the genetic interaction networks beyond yeast will provide not only key insights into the functional properties of genes, but also a better understanding of the background effects and the (un)predictability of traits in a broader context.
Collapse
|
66
|
A New Strategy to Control and Eradicate "Undruggable" Oncogenic K-RAS-Driven Pancreatic Cancer: Molecular Insights and Core Principles Learned from Developmental and Evolutionary Biology. Cancers (Basel) 2018; 10:cancers10050142. [PMID: 29757973 PMCID: PMC5977115 DOI: 10.3390/cancers10050142] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/08/2018] [Accepted: 05/10/2018] [Indexed: 12/15/2022] Open
Abstract
Oncogenic K-RAS mutations are found in virtually all pancreatic cancers, making K-RAS one of the most targeted oncoproteins for drug development in cancer therapies. Despite intense research efforts over the past three decades, oncogenic K-RAS has remained largely “undruggable”. Rather than targeting an upstream component of the RAS signaling pathway (i.e., EGFR/HER2) and/or the midstream effector kinases (i.e., RAF/MEK/ERK/PI3K/mTOR), we propose an alternative strategy to control oncogenic K-RAS signal by targeting its most downstream signaling module, Seven-In-Absentia Homolog (SIAH). SIAH E3 ligase controls the signal output of oncogenic K-RAS hyperactivation that drives unchecked cell proliferation, uncontrolled tumor growth, and rapid cancer cell dissemination in human pancreatic cancer. Therefore, SIAH is an ideal therapeutic target as it is an extraordinarily conserved downstream signaling gatekeeper indispensable for proper RAS signaling. Guided by molecular insights and core principles obtained from developmental and evolutionary biology, we propose an anti-SIAH-centered anti-K-RAS strategy as a logical and alternative anticancer strategy to dampen uncontrolled K-RAS hyperactivation and halt tumor growth and metastasis in pancreatic cancer. The clinical utility of developing SIAH as both a tumor-specific and therapy-responsive biomarker, as well as a viable anti-K-RAS drug target, is logically simple and conceptually innovative. SIAH clearly constitutes a major tumor vulnerability and K-RAS signaling bottleneck in pancreatic ductal adenocarcinoma (PDAC). Given the high degree of evolutionary conservation in the K-RAS/SIAH signaling pathway, an anti-SIAH-based anti-PDAC therapy will synergize with covalent K-RAS inhibitors and direct K-RAS targeted initiatives to control and eradicate pancreatic cancer in the future.
Collapse
|
67
|
Same-Sex Twin Pair Phenotypic Correlations are Consistent with Human Y Chromosome Promoting Phenotypic Heterogeneity. Evol Biol 2018. [DOI: 10.1007/s11692-018-9454-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
|
68
|
Kuzmin E, VanderSluis B, Wang W, Tan G, Deshpande R, Chen Y, Usaj M, Balint A, Mattiazzi Usaj M, van Leeuwen J, Koch EN, Pons C, Dagilis AJ, Pryszlak M, Wang JZY, Hanchard J, Riggi M, Xu K, Heydari H, San Luis BJ, Shuteriqi E, Zhu H, Van Dyk N, Sharifpoor S, Costanzo M, Loewith R, Caudy A, Bolnick D, Brown GW, Andrews BJ, Boone C, Myers CL. Systematic analysis of complex genetic interactions. Science 2018; 360:eaao1729. [PMID: 29674565 PMCID: PMC6215713 DOI: 10.1126/science.aao1729] [Citation(s) in RCA: 159] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Accepted: 02/23/2018] [Indexed: 12/11/2022]
Abstract
To systematically explore complex genetic interactions, we constructed ~200,000 yeast triple mutants and scored negative trigenic interactions. We selected double-mutant query genes across a broad spectrum of biological processes, spanning a range of quantitative features of the global digenic interaction network and tested for a genetic interaction with a third mutation. Trigenic interactions often occurred among functionally related genes, and essential genes were hubs on the trigenic network. Despite their functional enrichment, trigenic interactions tended to link genes in distant bioprocesses and displayed a weaker magnitude than digenic interactions. We estimate that the global trigenic interaction network is ~100 times as large as the global digenic network, highlighting the potential for complex genetic interactions to affect the biology of inheritance, including the genotype-to-phenotype relationship.
Collapse
Affiliation(s)
- Elena Kuzmin
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Benjamin VanderSluis
- Department of Computer Science and Engineering, University of Minnesota-Twin Cities, 200 Union Street, Minneapolis, MN 55455, USA
| | - Wen Wang
- Department of Computer Science and Engineering, University of Minnesota-Twin Cities, 200 Union Street, Minneapolis, MN 55455, USA
| | - Guihong Tan
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Raamesh Deshpande
- Department of Computer Science and Engineering, University of Minnesota-Twin Cities, 200 Union Street, Minneapolis, MN 55455, USA
| | - Yiqun Chen
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Matej Usaj
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Attila Balint
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- Department of Biochemistry, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Mojca Mattiazzi Usaj
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Jolanda van Leeuwen
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Elizabeth N Koch
- Department of Computer Science and Engineering, University of Minnesota-Twin Cities, 200 Union Street, Minneapolis, MN 55455, USA
| | - Carles Pons
- Department of Computer Science and Engineering, University of Minnesota-Twin Cities, 200 Union Street, Minneapolis, MN 55455, USA
| | - Andrius J Dagilis
- Department of Integrative Biology, 1 University Station C0990, University of Texas at Austin, Austin, TX 78712, USA
| | - Michael Pryszlak
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Jason Zi Yang Wang
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Julia Hanchard
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Margot Riggi
- Department of Molecular Biology, University of Geneva, Geneva 1211, Switzerland
- Department of Biochemistry, University of Geneva, 1211 Geneva, Switzerland
- iGE3 (Institute of Genetics and Genomics of Geneva), 1211 Geneva, Switzerland
- Swiss National Centre for Competence in Research Programme Chemical Biology, 1211 Geneva, Switzerland
| | - Kaicong Xu
- Department of Computer Science and Engineering, University of Minnesota-Twin Cities, 200 Union Street, Minneapolis, MN 55455, USA
| | - Hamed Heydari
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Bryan-Joseph San Luis
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Ermira Shuteriqi
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Hongwei Zhu
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Nydia Van Dyk
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Sara Sharifpoor
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Michael Costanzo
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Robbie Loewith
- Department of Molecular Biology, University of Geneva, Geneva 1211, Switzerland
- iGE3 (Institute of Genetics and Genomics of Geneva), 1211 Geneva, Switzerland
- Swiss National Centre for Competence in Research Programme Chemical Biology, 1211 Geneva, Switzerland
| | - Amy Caudy
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Daniel Bolnick
- Department of Integrative Biology, 1 University Station C0990, University of Texas at Austin, Austin, TX 78712, USA
| | - Grant W Brown
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- Department of Biochemistry, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Brenda J Andrews
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada.
- Department of Molecular Genetics, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Charles Boone
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada.
- Department of Molecular Genetics, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- RIKEN Center for Sustainable Resource Science, Wako, Saitama, Japan
| | - Chad L Myers
- Department of Computer Science and Engineering, University of Minnesota-Twin Cities, 200 Union Street, Minneapolis, MN 55455, USA.
| |
Collapse
|
69
|
Sardi M, Gasch AP. Genetic background effects in quantitative genetics: gene-by-system interactions. Curr Genet 2018; 64:1173-1176. [PMID: 29644456 DOI: 10.1007/s00294-018-0835-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 04/04/2018] [Accepted: 04/06/2018] [Indexed: 01/18/2023]
Abstract
Proper cell function depends on networks of proteins that interact physically and functionally to carry out physiological processes. Thus, it seems logical that the impact of sequence variation in one protein could be significantly influenced by genetic variants at other loci in a genome. Nonetheless, the importance of such genetic interactions, known as epistasis, in explaining phenotypic variation remains a matter of debate in genetics. Recent work from our lab revealed that genes implicated from an association study of toxin tolerance in Saccharomyces cerevisiae show extensive interactions with the genetic background: most implicated genes, regardless of allele, are important for toxin tolerance in only one of two tested strains. The prevalence of background effects in our study adds to other reports of widespread genetic-background interactions in model organisms. We suggest that these effects represent many-way interactions with myriad features of the cellular system that vary across classes of individuals. Such gene-by-system interactions may influence diverse traits and require new modeling approaches to accurately represent genotype-phenotype relationships across individuals.
Collapse
Affiliation(s)
- Maria Sardi
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Cargill, Incorporated, Minneapolis, MN, 55440, USA
| | - Audrey P Gasch
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, 53706, USA.
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, 53706, USA.
| |
Collapse
|
70
|
Schrag TA, Westhues M, Schipprack W, Seifert F, Thiemann A, Scholten S, Melchinger AE. Beyond Genomic Prediction: Combining Different Types of omics Data Can Improve Prediction of Hybrid Performance in Maize. Genetics 2018; 208:1373-1385. [PMID: 29363551 PMCID: PMC5887136 DOI: 10.1534/genetics.117.300374] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 01/20/2018] [Indexed: 01/28/2023] Open
Abstract
The ability to predict the agronomic performance of single-crosses with high precision is essential for selecting superior candidates for hybrid breeding. With recent technological advances, thousands of new parent lines, and, consequently, millions of new hybrid combinations are possible in each breeding cycle, yet only a few hundred can be produced and phenotyped in multi-environment yield trials. Well established prediction approaches such as best linear unbiased prediction (BLUP) using pedigree data and whole-genome prediction using genomic data are limited in capturing epistasis and interactions occurring within and among downstream biological strata such as transcriptome and metabolome. Because mRNA and small RNA (sRNA) sequences are involved in transcriptional, translational and post-translational processes, we expect them to provide information influencing several biological strata. However, using sRNA data of parent lines to predict hybrid performance has not yet been addressed. Here, we gathered genomic, transcriptomic (mRNA and sRNA) and metabolomic data of parent lines to evaluate the ability of the data to predict the performance of untested hybrids for important agronomic traits in grain maize. We found a considerable interaction for predictive ability between predictor and trait, with mRNA data being a superior predictor for grain yield and genomic data for grain dry matter content, while sRNA performed relatively poorly for both traits. Combining mRNA and genomic data as predictors resulted in high predictive abilities across both traits and combining other predictors improved prediction over that of the individual predictors alone. We conclude that downstream "omics" can complement genomics for hybrid prediction, and, thereby, contribute to more efficient selection of hybrid candidates.
Collapse
Affiliation(s)
- Tobias A Schrag
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70599 Stuttgart, Germany
| | - Matthias Westhues
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70599 Stuttgart, Germany
| | - Wolfgang Schipprack
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70599 Stuttgart, Germany
| | - Felix Seifert
- Biocenter Klein Flottbek, Developmental Biology and Biotechnology, University of Hamburg, 22609 Hamburg, Germany
| | - Alexander Thiemann
- Biocenter Klein Flottbek, Developmental Biology and Biotechnology, University of Hamburg, 22609 Hamburg, Germany
| | - Stefan Scholten
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70599 Stuttgart, Germany
| | - Albrecht E Melchinger
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70599 Stuttgart, Germany
| |
Collapse
|
71
|
Chistyakov VA, Denisenko YV, Bren AB. Presence of Old Individuals in a Population Accelerates and Optimizes the Process of Selection: in silico Experiments. BIOCHEMISTRY (MOSCOW) 2018; 83:159-167. [DOI: 10.1134/s0006297918020086] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
72
|
Weinreich DM, Lan Y, Jaffe J, Heckendorn RB. The Influence of Higher-Order Epistasis on Biological Fitness Landscape Topography. JOURNAL OF STATISTICAL PHYSICS 2018; 172:208-225. [PMID: 29904213 PMCID: PMC5986866 DOI: 10.1007/s10955-018-1975-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 01/24/2018] [Indexed: 05/31/2023]
Abstract
The effect of a mutation on the organism often depends on what other mutations are already present in its genome. Geneticists refer to such mutational interactions as epistasis. Pairwise epistatic effects have been recognized for over a century, and their evolutionary implications have received theoretical attention for nearly as long. However, pairwise epistatic interactions themselves can vary with genomic background. This is called higher-order epistasis, and its consequences for evolution are much less well understood. Here, we assess the influence that higher-order epistasis has on the topography of 16 published, biological fitness landscapes. We find that on average, their effects on fitness landscape declines with order, and suggest that notable exceptions to this trend may deserve experimental scrutiny. We conclude by highlighting opportunities for further theoretical and experimental work dissecting the influence that epistasis of all orders has on fitness landscape topography and on the efficiency of evolution by natural selection.
Collapse
Affiliation(s)
- Daniel M. Weinreich
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912 USA
- Center for Computational Molecular Biology, Brown University, Providence, RI 02912 USA
| | - Yinghong Lan
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912 USA
| | - Jacob Jaffe
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912 USA
| | - Robert B. Heckendorn
- Computer Science Department, University of Idaho, 875 Perimeter Drive, MS 1010, Moscow, ID 83844 USA
| |
Collapse
|
73
|
Abstract
Accumulating evidence suggests that many classes of DNA repeats exhibit attributes that distinguish them from other genetic variants, including the fact that they are more liable to mutation; this enables them to mediate genetic plasticity. The expansion of tandem repeats, particularly of short tandem repeats, can cause a range of disorders (including Huntington disease, various ataxias, motor neuron disease, frontotemporal dementia, fragile X syndrome and other neurological disorders), and emerging data suggest that tandem repeat polymorphisms (TRPs) can also regulate gene expression in healthy individuals. TRPs in human genomes may also contribute to the missing heritability of polygenic disorders. A better understanding of tandem repeats and their associated repeatome, as well as their capacity for genetic plasticity via both germline and somatic mutations, is needed to transform our understanding of the role of TRPs in health and disease.
Collapse
Affiliation(s)
- Anthony J Hannan
- Florey Institute of Neuroscience and Mental Health, University of Melbourne.,Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia
| |
Collapse
|
74
|
Abstract
PURPOSE OF REVIEW To review the evidence for genetic modifier effects in the neurodegenerative diseases Huntington's Disease (HD), Frontotemporal Lobar Degeneration (FTLD), Alzheimer's Disease (AD), and Parkinson's Disease (PD). RECENT FINDINGS Increasingly, we understand human disease genetics less through the lens of single-locus/single-trait effects, and more through that of polygenic contributions to disease risk. In addition, specific examples of genetic modifier effects of the chromosome 7 gene TMEM106B on various target genes including those causal for Mendelian classes of FTLD - GRN and c9orf72 - have emerged from both genetic cohort studies and mechanistic examinations of biological pathways. SUMMARY Here, we summarize the literature reporting genetic modifier effects in HD, FTLD, AD, and PD. We further contextualize reported genetic modifier effects in these diseases in terms of insight they may lend to the concept of a polygenic landscape for the major neurodegenerative diseases.
Collapse
Affiliation(s)
- Nimansha Jain
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Alice S Chen-Plotkin
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| |
Collapse
|
75
|
Forsberg SKG, Carlborg Ö. On the relationship between epistasis and genetic variance heterogeneity. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:5431-5438. [PMID: 28992256 DOI: 10.1093/jxb/erx283] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 07/18/2017] [Indexed: 06/07/2023]
Abstract
Epistasis and genetic variance heterogeneity are two non-additive genetic inheritance patterns that are often, but not always, related. Here we use theoretical examples and empirical results from earlier analyses of experimental data to illustrate the connection between the two. This includes an introduction to the relationship between epistatic gene action, statistical epistasis, and genetic variance heterogeneity, and a brief discussion about how genetic processes other than epistasis can also give rise to genetic variance heterogeneity.
Collapse
Affiliation(s)
- Simon K G Forsberg
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, SE-75123 Uppsala, Sweden
| | - Örjan Carlborg
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, SE-75123 Uppsala, Sweden
| |
Collapse
|
76
|
Chen A, Liu Y, Williams SM, Morris N, Buchner DA. Widespread epistasis regulates glucose homeostasis and gene expression. PLoS Genet 2017; 13:e1007025. [PMID: 28961251 PMCID: PMC5636166 DOI: 10.1371/journal.pgen.1007025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 10/11/2017] [Accepted: 09/17/2017] [Indexed: 02/07/2023] Open
Abstract
The relative contributions of additive versus non-additive interactions in the regulation of complex traits remains controversial. This may be in part because large-scale epistasis has traditionally been difficult to detect in complex, multi-cellular organisms. We hypothesized that it would be easier to detect interactions using mouse chromosome substitution strains that simultaneously incorporate allelic variation in many genes on a controlled genetic background. Analyzing metabolic traits and gene expression levels in the offspring of a series of crosses between mouse chromosome substitution strains demonstrated that inter-chromosomal epistasis was a dominant feature of these complex traits. Epistasis typically accounted for a larger proportion of the heritable effects than those due solely to additive effects. These epistatic interactions typically resulted in trait values returning to the levels of the parental CSS host strain. Due to the large epistatic effects, analyses that did not account for interactions consistently underestimated the true effect sizes due to allelic variation or failed to detect the loci controlling trait variation. These studies demonstrate that epistatic interactions are a common feature of complex traits and thus identifying these interactions is key to understanding their genetic regulation. Most complex traits and diseases are regulated by the combined influence of multiple genetic variants. However, it remains controversial whether these genetic variants independently influence complex traits, and therefore the impact of each variant could be simply added together (additivity), or whether the variants work together to influence trait variation, in which case the combined impact of multiple variants would differ from the summed impact of each individual variant (epistasis). In this study in mice, we discovered that the genetic regulation of blood sugar levels and gene expression in the liver were predominantly controlled by non-additive interactions, whereas body weight was predominantly controlled by additive interactions. Remarkably, the expression level of nearly 25% of all genes in the liver was controlled by non-additive interactions. The non-additive interactions typically acted to return trait values to the levels detected in control mice, thus contributing to a reduction in trait variation. We also demonstrated that not accounting for non-additive interactions significantly underestimated the phenotypic effect of a genetic variant on a particular genetic background, suggesting that many previously identified risk loci may have significantly larger effects on disease susceptibility in a subset of individuals. These studies highlight the importance of understanding interactions between genetic variants to better understand disease risk and personalize clinical care.
Collapse
Affiliation(s)
- Anlu Chen
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, United States of America
| | - Yang Liu
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, United States of America
| | - Scott M. Williams
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH, United States of America
| | - Nathan Morris
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH, United States of America
| | - David A. Buchner
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, United States of America
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, United States of America
- * E-mail:
| |
Collapse
|
77
|
Westhues M, Schrag TA, Heuer C, Thaller G, Utz HF, Schipprack W, Thiemann A, Seifert F, Ehret A, Schlereth A, Stitt M, Nikoloski Z, Willmitzer L, Schön CC, Scholten S, Melchinger AE. Omics-based hybrid prediction in maize. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2017. [PMID: 28647896 DOI: 10.1007/s00122-017-2934-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Complementing genomic data with other "omics" predictors can increase the probability of success for predicting the best hybrid combinations using complex agronomic traits. Accurate prediction of traits with complex genetic architecture is crucial for selecting superior candidates in animal and plant breeding and for guiding decisions in personalized medicine. Whole-genome prediction has revolutionized these areas but has inherent limitations in incorporating intricate epistatic interactions. Downstream "omics" data are expected to integrate interactions within and between different biological strata and provide the opportunity to improve trait prediction. Yet, predicting traits from parents to progeny has not been addressed by a combination of "omics" data. Here, we evaluate several "omics" predictors-genomic, transcriptomic and metabolic data-measured on parent lines at early developmental stages and demonstrate that the integration of transcriptomic with genomic data leads to higher success rates in the correct prediction of untested hybrid combinations in maize. Despite the high predictive ability of genomic data, transcriptomic data alone outperformed them and other predictors for the most complex heterotic trait, dry matter yield. An eQTL analysis revealed that transcriptomic data integrate genomic information from both, adjacent and distant sites relative to the expressed genes. Together, these findings suggest that downstream predictors capture physiological epistasis that is transmitted from parents to their hybrid offspring. We conclude that the use of downstream "omics" data in prediction can exploit important information beyond structural genomics for leveraging the efficiency of hybrid breeding.
Collapse
Affiliation(s)
- Matthias Westhues
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70599, Stuttgart, Germany
| | - Tobias A Schrag
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70599, Stuttgart, Germany
| | - Claas Heuer
- Institute of Animal Breeding and Husbandry, Christian-Albrechts-University Kiel, 24098, Kiel, Germany
- Inguran LLC dba STGenetics, 22575 SH6 South, Navasota, TX, 77868, USA
| | - Georg Thaller
- Institute of Animal Breeding and Husbandry, Christian-Albrechts-University Kiel, 24098, Kiel, Germany
| | - H Friedrich Utz
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70599, Stuttgart, Germany
| | - Wolfgang Schipprack
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70599, Stuttgart, Germany
| | - Alexander Thiemann
- Biocenter Klein Flottbek, Developmental Biology and Biotechnology, University of Hamburg, 22609, Hamburg, Germany
| | - Felix Seifert
- Biocenter Klein Flottbek, Developmental Biology and Biotechnology, University of Hamburg, 22609, Hamburg, Germany
| | - Anita Ehret
- Institute of Animal Breeding and Husbandry, Christian-Albrechts-University Kiel, 24098, Kiel, Germany
| | - Armin Schlereth
- Max-Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Mark Stitt
- Max-Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Zoran Nikoloski
- Max-Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Lothar Willmitzer
- Max-Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Chris C Schön
- Plant Breeding, Technische Universität München, 85354, Freising, Germany
| | - Stefan Scholten
- Biocenter Klein Flottbek, Developmental Biology and Biotechnology, University of Hamburg, 22609, Hamburg, Germany.
| | - Albrecht E Melchinger
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70599, Stuttgart, Germany.
| |
Collapse
|
78
|
Riordan JD, Nadeau JH. From Peas to Disease: Modifier Genes, Network Resilience, and the Genetics of Health. Am J Hum Genet 2017; 101:177-191. [PMID: 28777930 PMCID: PMC5544383 DOI: 10.1016/j.ajhg.2017.06.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Phenotypes are rarely consistent across genetic backgrounds and environments, but instead vary in many ways depending on allelic variants, unlinked genes, epigenetic factors, and environmental exposures. In the extreme, individuals carrying the same causal DNA sequence variant but on different backgrounds can be classified as having distinct conditions. Similarly, some individuals that carry disease alleles are nevertheless healthy despite affected family members in the same environment. These genetic background effects often result from the action of so-called "modifier genes" that modulate the phenotypic manifestation of target genes in an epistatic manner. While complicating the prospects for gene discovery and the feasibility of mechanistic studies, such effects are opportunities to gain a deeper understanding of gene interaction networks that provide organismal form and function as well as resilience to perturbation. Here, we review the principles of modifier genetics and assess progress in studies of modifier genes and their targets in both simple and complex traits. We propose that modifier effects emerge from gene interaction networks whose structure and function vary with genetic background and argue that these effects can be exploited as safe and effective ways to prevent, stabilize, and reverse disease and dysfunction.
Collapse
Affiliation(s)
- Jesse D Riordan
- Pacific Northwest Research Institute, Seattle, WA 98122, USA.
| | - Joseph H Nadeau
- Pacific Northwest Research Institute, Seattle, WA 98122, USA.
| |
Collapse
|
79
|
Abstract
Pharmacogenomics (PGx), a substantial component of "personalized medicine", seeks to understand each individual's genetic composition to optimize drug therapy -- maximizing beneficial drug response, while minimizing adverse drug reactions (ADRs). Drug responses are highly variable because innumerable factors contribute to ultimate phenotypic outcomes. Recent genome-wide PGx studies have provided some insight into genetic basis of variability in drug response. These can be grouped into three categories. [a] Monogenic (Mendelian) traits include early examples mostly of inherited disorders, and some severe (idiosyncratic) ADRs typically influenced by single rare coding variants. [b] Predominantly oligogenic traits represent variation largely influenced by a small number of major pharmacokinetic or pharmacodynamic genes. [c] Complex PGx traits resemble most multifactorial quantitative traits -- influenced by numerous small-effect variants, together with epigenetic effects and environmental factors. Prediction of monogenic drug responses is relatively simple, involving detection of underlying mutations; due to rarity of these events and incomplete penetrance, however, prospective tests based on genotype will have high false-positive rates, plus pharmacoeconomics will require justification. Prediction of predominantly oligogenic traits is slowly improving. Although a substantial fraction of variation can be explained by limited numbers of large-effect genetic variants, uncertainty in successful predictions and overall cost-benefit ratios will make such tests elusive for everyday clinical use. Prediction of complex PGx traits is almost impossible in the foreseeable future. Genome-wide association studies of large cohorts will continue to discover relevant genetic variants; however, these small-effect variants, combined, explain only a small fraction of phenotypic variance -- thus having limited predictive power and clinical utility.
Collapse
Affiliation(s)
- Ge Zhang
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229-3039, United States.
| | - Daniel W Nebert
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229-3039, United States; Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati School of Medicine, Cincinnati, OH 45267-0056, United States.
| |
Collapse
|
80
|
Horwitz AV. Social Context, Biology, and the Definition of Disorder. JOURNAL OF HEALTH AND SOCIAL BEHAVIOR 2017; 58:131-145. [PMID: 28661776 DOI: 10.1177/0022146517705165] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In recent years, medical sociologists have increasingly paid attention to a variety of interactions between social and biological factors. These include how social stressors impact the functioning of physiological systems, how sociocultural contexts trigger genetic propensities or mitigate genetic defects, and how brains are attuned to social, cultural, and interactional factors. This paper focuses on how both sociocultural and biological forces influence what conditions are contextually appropriate responses or disorders. It also suggests that some of the most obdurate health problems result from mismatches between natural genes and current social circumstances rather than from genetic defects. Finally, it examines how social environments have profound impacts on how much harm disorders create. It shows how sociological insights can help establish valid criteria for illnesses and indicates the complexities involved in defining what genuine disorders are.
Collapse
|
81
|
Lagator M, Paixão T, Barton NH, Bollback JP, Guet CC. On the mechanistic nature of epistasis in a canonical cis-regulatory element. eLife 2017; 6. [PMID: 28518057 PMCID: PMC5481185 DOI: 10.7554/elife.25192] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 05/17/2017] [Indexed: 01/02/2023] Open
Abstract
Understanding the relation between genotype and phenotype remains a major challenge. The difficulty of predicting individual mutation effects, and particularly the interactions between them, has prevented the development of a comprehensive theory that links genotypic changes to their phenotypic effects. We show that a general thermodynamic framework for gene regulation, based on a biophysical understanding of protein-DNA binding, accurately predicts the sign of epistasis in a canonical cis-regulatory element consisting of overlapping RNA polymerase and repressor binding sites. Sign and magnitude of individual mutation effects are sufficient to predict the sign of epistasis and its environmental dependence. Thus, the thermodynamic model offers the correct null prediction for epistasis between mutations across DNA-binding sites. Our results indicate that a predictive theory for the effects of cis-regulatory mutations is possible from first principles, as long as the essential molecular mechanisms and the constraints these impose on a biological system are accounted for. DOI:http://dx.doi.org/10.7554/eLife.25192.001 Mutations are changes to DNA that provide the raw material upon which evolution can act. Therefore, to understand evolution, we need to know the effects of mutations, and how those mutations interact with each other (a phenomenon referred to as epistasis). So far, few mathematical models allow scientists to predict the effects of mutations, and even fewer are able to predict epistasis. Biological systems are complex and consist of many proteins and other molecules. Genes are the sections of DNA that provide the instructions needed to produce these molecules, and some genes encode proteins that can bind to DNA to control whether other genes are switched on or off. Lagator, Paixão et al. have now used mathematical models and experiments to understand how the environment inside the cells of a bacterium known as E. coli, specifically the amount of particular proteins, affects epistasis. These mathematical models are able to predict interactions between mutations in the most abundant class of DNA-binding sites in proteins. This approach found that the nature of the interaction between mutations can be explained through biophysical laws, combined with the basic knowledge of the logic of how genes regulate each other’s activities. Furthermore, the models allow Lagator, Paixão et al. to predict interactions between mutations in several different environments, such as the presence of a new food source or a toxin, defined by the amounts of relevant DNA-binding proteins in cells. By providing new ways of understanding how genes are regulated in bacteria, and how gene regulation is affected by mutations, these findings contribute to our understanding of how organisms evolve. In addition, this work may help us to build artificial networks of genes that interact with each other to produce a desired response, such as more efficient production of fuel from ethanol or the break down of hazardous chemicals. DOI:http://dx.doi.org/10.7554/eLife.25192.002
Collapse
Affiliation(s)
- Mato Lagator
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Tiago Paixão
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Nicholas H Barton
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Jonathan P Bollback
- Institute of Science and Technology Austria, Klosterneuburg, Austria.,Department of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Călin C Guet
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| |
Collapse
|
82
|
Epistasis in Neuropsychiatric Disorders. Trends Genet 2017; 33:256-265. [PMID: 28268034 DOI: 10.1016/j.tig.2017.01.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 01/25/2017] [Accepted: 01/27/2017] [Indexed: 12/12/2022]
Abstract
The contribution of epistasis to human disease remains unclear. However, several studies have now identified epistatic interactions between common variants that increase the risk of a neuropsychiatric disorder, while there is growing evidence that genetic interactions contribute to the pathogenicity of rare, multigenic copy-number variants (CNVs) that have been observed in patients. This review discusses the current evidence for epistatic events and genetic interactions in neuropsychiatric disorders, how paradigm shifts in the phenotypic classification of patients would empower the search for epistatic effects, and how network and cellular models might be employed to further elucidate relevant epistatic interactions.
Collapse
|
83
|
Dietz HC. 2016 Presidential Address: Let's Make Human Genetics Great (Again): The Importance of Beauty in Science. Am J Hum Genet 2017; 100:379-384. [PMID: 28257683 DOI: 10.1016/j.ajhg.2017.01.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
|
84
|
Construction of a minimal genome as a chassis for synthetic biology. Essays Biochem 2016; 60:337-346. [DOI: 10.1042/ebc20160024] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 09/26/2016] [Accepted: 09/29/2016] [Indexed: 12/15/2022]
Abstract
Microbial diversity and complexity pose challenges in understanding the voluminous genetic information produced from whole-genome sequences, bioinformatics and high-throughput ‘-omics’ research. These challenges can be overcome by a core blueprint of a genome drawn with a minimal gene set, which is essential for life. Systems biology and large-scale gene inactivation studies have estimated the number of essential genes to be ∼300–500 in many microbial genomes. On the basis of the essential gene set information, minimal-genome strains have been generated using sophisticated genome engineering techniques, such as genome reduction and chemical genome synthesis. Current size-reduced genomes are not perfect minimal genomes, but chemically synthesized genomes have just been constructed. Some minimal genomes provide various desirable functions for bioindustry, such as improved genome stability, increased transformation efficacy and improved production of biomaterials. The minimal genome as a chassis genome for synthetic biology can be used to construct custom-designed genomes for various practical and industrial applications.
Collapse
|
85
|
Visscher PM, Wray NR. Concepts and Misconceptions about the Polygenic Additive Model Applied to Disease. Hum Hered 2016; 80:165-70. [PMID: 27576756 DOI: 10.1159/000446931] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
It is nearly one hundred years, since R.A. Fisher published his now famous paper that started the field of quantitative genetics. That paper reconciled Mendelian genetics (as exemplified by Mendel's peas) and the biometrical approach to quantitative traits (as exemplified by the correlation and regression approaches from Galton and Pearson), by showing that a simple model of many genes of small effects, each following Mendel's laws of segregation and inheritance, plus environmental variation could account for the observed resemblance between relatives. In this review, we discuss a number of concepts and misconceptions about the assumptions and limitations of polygenic models of common diseases in human populations.
Collapse
|