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Li J, Bank C. Dominance and multi-locus interaction. Trends Genet 2024; 40:364-378. [PMID: 38453542 DOI: 10.1016/j.tig.2023.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 12/03/2023] [Accepted: 12/04/2023] [Indexed: 03/09/2024]
Abstract
Dominance is usually considered a constant value that describes the relative difference in fitness or phenotype between heterozygotes and the average of homozygotes at a focal polymorphic locus. However, the observed dominance can vary with the genetic background of the focal locus. Here, alleles at other loci modify the observed phenotype through position effects or dominance modifiers that are sometimes associated with pathogen resistance, lineage, sex, or mating type. Theoretical models have illustrated how variable dominance appears in the context of multi-locus interaction (epistasis). Here, we review empirical evidence for variable dominance and how the observed patterns may be captured by proposed epistatic models. We highlight how integrating epistasis and dominance is crucial for comprehensively understanding adaptation and speciation.
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Affiliation(s)
- Juan Li
- Institute of Ecology and Evolution, University of Bern, Bern, Switzerland; Swiss Institute for Bioinformatics, Lausanne, Switzerland.
| | - Claudia Bank
- Institute of Ecology and Evolution, University of Bern, Bern, Switzerland; Swiss Institute for Bioinformatics, Lausanne, Switzerland
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2
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Belaid B, Lamara Mahammed L, Mohand Oussaid A, Migaud M, Khadri Y, Casanova JL, Puel A, Ben Halla N, Djidjik R. Case Report: Interleukin-2 Receptor Common Gamma Chain Defect Presented as a Hyper-IgE Syndrome. Front Immunol 2021; 12:696350. [PMID: 34248995 PMCID: PMC8264782 DOI: 10.3389/fimmu.2021.696350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 06/07/2021] [Indexed: 11/16/2022] Open
Abstract
X-linked severe combined immunodeficiency (X-SCID) is caused by mutations of IL2RG, the gene encoding the interleukin common gamma chain (IL-2Rγ or γc) of cytokine receptors for interleukin (IL)-2, IL-4, IL-7, IL-9, IL-15, and IL-21. Hypomorphic mutations of IL2RG may cause combined immunodeficiencies with atypical clinical and immunological presentations. Here, we report a clinical, immunological, and functional characterization of a missense mutation in exon 1 (c.115G>A; p. Asp39Asn) of IL2RG in a 7-year-old boy. The patient suffered from recurrent sinopulmonary infections and refractory eczema. His total lymphocyte counts have remained normal despite skewed T cell subsets, with a pronounced serum IgE elevation. Surface expression of IL-2Rγ was reduced on his lymphocytes. Signal transducer and activator of transcription (STAT) phosphorylation in response to IL-2, IL-4, and IL-7 showed a partially preserved receptor function. T-cell proliferation in response to mitogens and anti-CD3/anti-CD28 monoclonal antibodies was significantly reduced. Further analysis revealed a decreased percentage of CD4+ T cells capable of secreting IFN-γ, but not IL-4 or IL-17. Studies on the functional consequences of IL-2Rγ variants are important to get more insight into the pathogenesis of atypical phenotypes which may lay the ground for novel therapeutic strategies.
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Affiliation(s)
- Brahim Belaid
- Department of Medical Immunology, Beni-Messous University Hospital Center, Algiers, Algeria.,Faculty of Medicine, Benyoucef Benkhedda University of Algiers 1, Algiers, Algeria
| | - Lydia Lamara Mahammed
- Department of Medical Immunology, Beni-Messous University Hospital Center, Algiers, Algeria.,Faculty of Medicine, Benyoucef Benkhedda University of Algiers 1, Algiers, Algeria
| | - Aida Mohand Oussaid
- Faculty of Medicine, Benyoucef Benkhedda University of Algiers 1, Algiers, Algeria.,Department of Pediatrics A, Beni-Messous University Hospital Center, Algiers, Algeria
| | - Melanie Migaud
- Laboratory of Human Genetics of Infectious Diseases, Necker Hospital for Sick Children, INSERM UMR 1163, Paris, France.,Imagine Institute, University of Paris, Paris, France
| | - Yasmine Khadri
- Department of Pediatrics A, Beni-Messous University Hospital Center, Algiers, Algeria
| | - Jean Laurent Casanova
- Laboratory of Human Genetics of Infectious Diseases, Necker Hospital for Sick Children, INSERM UMR 1163, Paris, France.,Imagine Institute, University of Paris, Paris, France.,St Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller University, New York, NY, United States.,Howard Hughes Medical Institute, New York, NY, United States
| | - Anne Puel
- Laboratory of Human Genetics of Infectious Diseases, Necker Hospital for Sick Children, INSERM UMR 1163, Paris, France.,Imagine Institute, University of Paris, Paris, France.,St Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller University, New York, NY, United States
| | - Nafissa Ben Halla
- Faculty of Medicine, Benyoucef Benkhedda University of Algiers 1, Algiers, Algeria.,Department of Pediatrics A, Beni-Messous University Hospital Center, Algiers, Algeria
| | - Reda Djidjik
- Department of Medical Immunology, Beni-Messous University Hospital Center, Algiers, Algeria.,Faculty of Medicine, Benyoucef Benkhedda University of Algiers 1, Algiers, Algeria
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3
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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.
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Hoekstra LA, Julick CR, Mika KM, Montooth KL. Energy demand and the context-dependent effects of genetic interactions underlying metabolism. Evol Lett 2018; 2:102-113. [PMID: 30283668 PMCID: PMC6121862 DOI: 10.1002/evl3.47] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 02/06/2018] [Accepted: 02/21/2018] [Indexed: 01/05/2023] Open
Abstract
Genetic effects are often context dependent, with the same genotype differentially affecting phenotypes across environments, life stages, and sexes. We used an environmental manipulation designed to increase energy demand during development to investigate energy demand as a general physiological explanation for context-dependent effects of mutations, particularly for those mutations that affect metabolism. We found that increasing the photoperiod during which Drosophila larvae are active during development phenocopies a temperature-dependent developmental delay in a mitochondrial-nuclear genotype with disrupted metabolism. This result indicates that the context-dependent fitness effects of this genotype are not specific to the effects of temperature and may generally result from variation in energy demand. The effects of this genotype also differ across life stages and between the sexes. The mitochondrial-nuclear genetic interaction disrupts metabolic rate in growing larvae, but not in adults, and compromises female, but not male, reproductive fitness. These patterns are consistent with a model where context-dependent genotype-phenotype relationships may generally arise from differences in energy demand experienced by individuals across environments, life stages, and sexes.
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Affiliation(s)
- Luke A Hoekstra
- Department of Evolution, Ecology and Organismal Biology Iowa State University Ames Iowa 50011
| | - Cole R Julick
- School of Biological Sciences University of Nebraska-Lincoln Lincoln Nebraska 68588
| | - Katelyn M Mika
- Department of Human Genetics University of Chicago Chicago Illinois 60637
| | - Kristi L Montooth
- School of Biological Sciences University of Nebraska-Lincoln Lincoln Nebraska 68588
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5
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Fournier T, Schacherer J. Genetic backgrounds and hidden trait complexity in natural populations. Curr Opin Genet Dev 2017; 47:48-53. [PMID: 28915487 PMCID: PMC5716861 DOI: 10.1016/j.gde.2017.08.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/09/2017] [Accepted: 08/31/2017] [Indexed: 11/29/2022]
Abstract
Dissecting the genetic basis of natural phenotypic variation is a major goal in biology. We know that most traits are strongly heritable. However, their genetic architecture is a long-standing question, which is unfortunately confounded by the lack of complete knowledge of the genetic components as well as their phenotypic effect in a specific genetic background. Many genetic variants are known to affect phenotypes but the same functional variant can have a different effect on the phenotype in different individuals of the same species. Understanding the impact of genetic background on the expressivity of a given phenotype is essential because this effect complicates our ability to predict phenotype from genotype. Here, we briefly review recent progress on the exploration of the effect of genetic background and we discuss how a deeper characterization of the inheritance, expressivity and genetic interactions hidden behind the phenotypic landscape of natural variation could provide a better understanding of the relationship between genotype and phenotype.
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Affiliation(s)
- Téo Fournier
- Université de Strasbourg, CNRS, GMGM UMR 7156, F-67000 Strasbourg, France
| | - Joseph Schacherer
- Université de Strasbourg, CNRS, GMGM UMR 7156, F-67000 Strasbourg, France.
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Kammenga JE. The background puzzle: how identical mutations in the same gene lead to different disease symptoms. FEBS J 2017; 284:3362-3373. [PMID: 28390082 DOI: 10.1111/febs.14080] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Revised: 03/31/2017] [Accepted: 04/05/2017] [Indexed: 01/05/2023]
Abstract
Identical disease-causing mutations can lead to different symptoms in different people. The reason for this has been a puzzling problem for geneticists. Differential penetrance and expressivity of mutations has been observed within individuals with different and similar genetic backgrounds. Attempts have been made to uncover the underlying mechanisms that determine differential phenotypic effects of identical mutations through studies of model organisms. From these studies evidence is accumulating that to understand disease mechanism or predict disease prevalence, an understanding of the influence of genetic background is as important as the putative disease-causing mutations of relatively large effect. This review highlights current insights into phenotypic variation due to gene interactions, epigenetics and stochasticity in model organisms, and discusses their importance for understanding the mutational effect on disease symptoms.
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Affiliation(s)
- Jan E Kammenga
- Laboratory of Nematology, Wageningen University, The Netherlands
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Na HJ, Park JS, Pyo JH, Jeon HJ, Kim YS, Arking R, Yoo MA. Metformin inhibits age-related centrosome amplification in Drosophila midgut stem cells through AKT/TOR pathway. Mech Ageing Dev 2015; 149:8-18. [PMID: 25988874 DOI: 10.1016/j.mad.2015.05.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/23/2015] [Accepted: 05/06/2015] [Indexed: 12/16/2022]
Abstract
We delineated the mechanism regulating the inhibition of centrosome amplification by metformin in Drosophila intestinal stem cells (ISCs). Age-related changes in tissue-resident stem cells may be closely associated with tissue aging and age-related diseases, such as cancer. Centrosome amplification is a hallmark of cancers. Our recent work showed that Drosophila ISCs are an excellent model for stem cell studies evaluating age-related increase in centrosome amplification. Here, we showed that metformin, a recognized anti-cancer drug, inhibits age- and oxidative stress-induced centrosome amplification in ISCs. Furthermore, we revealed that this effect is mediated via down-regulation of AKT/target of rapamycin (TOR) activity, suggesting that metformin prevents centrosome amplification by inhibiting the TOR signaling pathway. Additionally, AKT/TOR signaling hyperactivation and metformin treatment indicated a strong correlation between DNA damage accumulation and centrosome amplification in ISCs, suggesting that DNA damage might mediate centrosome amplification. Our study reveals the beneficial and protective effects of metformin on centrosome amplification via AKT/TOR signaling modulation. We identified a new target for the inhibition of age- and oxidative stress-induced centrosome amplification. We propose that the Drosophila ISCs may be an excellent model system for in vivo studies evaluating the effects of anti-cancer drugs on tissue-resident stem cell aging.
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Affiliation(s)
- Hyun-Jin Na
- Department of Molecular Biology, Pusan National University, Busan 609-735, South Korea
| | - Joung-Sun Park
- Department of Molecular Biology, Pusan National University, Busan 609-735, South Korea
| | - Jung-Hoon Pyo
- Department of Molecular Biology, Pusan National University, Busan 609-735, South Korea
| | - Ho-Jun Jeon
- Department of Molecular Biology, Pusan National University, Busan 609-735, South Korea
| | - Young-Shin Kim
- Department of Molecular Biology, Pusan National University, Busan 609-735, South Korea
| | - Robert Arking
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Mi-Ae Yoo
- Department of Molecular Biology, Pusan National University, Busan 609-735, South Korea.
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