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Hwang HY, Wang J. Fast genetic mapping using insertion-deletion polymorphisms in Caenorhabditis elegans. Sci Rep 2021; 11:11017. [PMID: 34040027 PMCID: PMC8155061 DOI: 10.1038/s41598-021-90190-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 05/07/2021] [Indexed: 11/09/2022] Open
Abstract
Genetic mapping is used in forward genetics to narrow the list of candidate mutations and genes corresponding to the mutant phenotype of interest. Even with modern advances in biology such as efficient identification of candidate mutations by whole-genome sequencing, mapping remains critical in pinpointing the responsible mutation. Here we describe a simple, fast, and affordable mapping toolkit that is particularly suitable for mapping in Caenorhabditis elegans. This mapping method uses insertion-deletion polymorphisms or indels that could be easily detected instead of single nucleotide polymorphisms in commonly used Hawaiian CB4856 mapping strain. The materials and methods were optimized so that mapping could be performed using tiny amount of genetic material without growing many large populations of mutants for DNA purification. We performed mapping of previously known and unknown mutations to show strengths and weaknesses of this method and to present examples of completed mapping. For situations where Hawaiian CB4856 is unsuitable, we provide an annotated list of indels as a basis for fast and easy mapping using other wild isolates. Finally, we provide rationale for using this mapping method over other alternatives as a part of a comprehensive strategy also involving whole-genome sequencing and other methods.
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Affiliation(s)
- Ho-Yon Hwang
- Department of Biochemistry and Molecular Biology, Department of Neuroscience, Johns Hopkins University, 615 N. Wolfe Street, E8410, Baltimore, MD, 21205, USA
| | - Jiou Wang
- Department of Biochemistry and Molecular Biology, Department of Neuroscience, Johns Hopkins University, 615 N. Wolfe Street, E8410, Baltimore, MD, 21205, USA.
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2
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Use of a Sibling Subtraction Method for Identifying Causal Mutations in Caenorhabditis elegans by Whole-Genome Sequencing. G3-GENES GENOMES GENETICS 2018; 8:669-678. [PMID: 29237702 PMCID: PMC5919755 DOI: 10.1534/g3.117.300135] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Whole-genome sequencing (WGS) is an indispensable tool for identifying causal mutations obtained from genetic screens. To reduce the number of causal mutation candidates typically uncovered by WGS, Caenorhabditis elegans researchers have developed several strategies. One involves crossing N2-background mutants to the polymorphic Hawaiian (HA) strain, which can be used to simultaneously identify mutant strain variants and obtain high-density mapping information. This approach, however, is not well suited for uncovering mutations in complex genetic backgrounds, and HA polymorphisms can alter phenotypes. Other approaches make use of DNA variants present in the initial background or introduced by mutagenesis. This information is used to implicate genomic regions with high densities of DNA lesions that persist after backcrossing, but these methods can provide lower resolution than HA mapping. To identify suppressor mutations using WGS, we developed an approach termed the sibling subtraction method (SSM). This method works by eliminating variants present in both mutants and their nonmutant siblings, thus greatly reducing the number of candidates. We used this method with two members of the C. elegans NimA-related kinase family, nekl-2 and nekl-3. Combining weak aphenotypic alleles of nekl-2 and nekl-3 leads to penetrant molting defects and larval arrest. We isolated ∼50 suppressors of nekl-2; nekl-3 synthetic lethality using F1 clonal screening methods and a peel-1–based counterselection strategy. When applied to five of the suppressors, SSM led to only one to four suppressor candidates per strain. Thus SSM is a powerful approach for identifying causal mutations in any genetic background and provides an alternative to current methods.
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Abstract
Numerous approaches have been taken in the hunt for human disease genes. The identification of such genes not only provides a great deal of information about the mechanism of disease development, but also provides potential avenues for better diagnosis and treatment. In this chapter, we review the use of the nonmammalian model organism C. elegans for the identification of human disease genes. Studies utilizing this relatively simple organism offer a good balance between the ability to recapitulate many aspects of human disease, while still offering an abundance of powerful cell biological, genetic, and genomic tools for disease gene discovery. C. elegans and other nonmammalian models have produced, and will continue to produce, key insights into human disease pathogenesis.
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Affiliation(s)
- Javier Apfeld
- Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - Scott Alper
- Department of Biomedical Research, Center for Genes, Environment and Health, National Jewish Health, Denver, CO, 80206, USA.
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, 80045, USA.
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Krebs MP, Collin GB, Hicks WL, Yu M, Charette JR, Shi LY, Wang J, Naggert JK, Peachey NS, Nishina PM. Mouse models of human ocular disease for translational research. PLoS One 2017; 12:e0183837. [PMID: 28859131 PMCID: PMC5578669 DOI: 10.1371/journal.pone.0183837] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 08/12/2017] [Indexed: 01/24/2023] Open
Abstract
Mouse models provide a valuable tool for exploring pathogenic mechanisms underlying inherited human disease. Here, we describe seven mouse models identified through the Translational Vision Research Models (TVRM) program, each carrying a new allele of a gene previously linked to retinal developmental and/or degenerative disease. The mutations include four alleles of three genes linked to human nonsyndromic ocular diseases (Aipl1tvrm119, Aipl1tvrm127, Rpgrip1tvrm111, RhoTvrm334) and three alleles of genes associated with human syndromic diseases that exhibit ocular phentoypes (Alms1tvrm102, Clcn2nmf289, Fkrptvrm53). Phenotypic characterization of each model is provided in the context of existing literature, in some cases refining our current understanding of specific disease attributes. These murine models, on fixed genetic backgrounds, are available for distribution upon request and may be useful for understanding the function of the gene in the retina, the pathological mechanisms induced by its disruption, and for testing experimental approaches to treat the corresponding human ocular diseases.
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Affiliation(s)
- Mark P. Krebs
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Gayle B. Collin
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Wanda L. Hicks
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Minzhong Yu
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
| | | | - Lan Ying Shi
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Jieping Wang
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | | | - Neal S. Peachey
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, United States of America
| | - Patsy M. Nishina
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
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Natural Genetic Variation in the Caenorhabditis elegans Response to Pseudomonas aeruginosa. G3-GENES GENOMES GENETICS 2017; 7:1137-1147. [PMID: 28179390 PMCID: PMC5386862 DOI: 10.1534/g3.117.039057] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Caenorhabditis elegans responds to pathogenic microorganisms by activating its innate immune system, which consists of physical barriers, behavioral responses, and microbial killing mechanisms. We examined whether natural variation plays a role in the response of C. elegans to Pseudomonas aeruginosa using two C. elegans strains that carry the same allele of npr-1, a gene that encodes a G-protein-coupled receptor related to mammalian neuropeptide Y receptors, but that differ in their genetic backgrounds. Strains carrying an allele for the NPR-1 215F isoform have been shown to exhibit lack of pathogen avoidance behavior and deficient immune response toward P. aeruginosa relative to the wild-type (N2) strain. We found that the wild isolate from Germany RC301, which carries the allele for NPR-1 215F, shows an enhanced resistance to P. aeruginosa infection when compared with strain DA650, which also carries NPR-1 215F but in an N2 background. Using a whole-genome sequencing single-nucleotide polymorphism (WGS-SNP) mapping strategy, we determined that the resistance to P. aeruginosa infection maps to a region on chromosome V. Furthermore, we demonstrated that the mechanism for the enhanced resistance to P. aeruginosa infection relies exclusively on strong P. aeruginosa avoidance behavior, and does not involve the main immune, stress, and lifespan extension pathways in C. elegans. Our findings underscore the importance of pathogen-specific behavioral immune defense in the wild, which seems to be favored over the more energy-costly mechanism of activation of physiological cellular defenses.
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Lehrbach NJ, Ji F, Sadreyev R. Next-Generation Sequencing for Identification of EMS-Induced Mutations in Caenorhabditis elegans. ACTA ACUST UNITED AC 2017; 117:7.29.1-7.29.12. [PMID: 28060408 DOI: 10.1002/cpmb.27] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Forward genetic analysis using chemical mutagenesis in model organisms is a powerful tool for investigation of molecular mechanisms in biological systems. In the nematode, Caenorhabditis elegans, mutagenesis screens using ethyl methanesulfonate (EMS) have led to important insights into genetic control of animal development and physiology. A major bottleneck to this approach is identification of the causative mutation underlying a phenotype of interest. In the past, this has required time-consuming genetic mapping experiments. More recently, next-generation sequencing technologies have allowed development of new methods for rapid mapping and identification of EMS-induced lesions. In this unit we describe a protocol to map and identify EMS-induced mutations in C. elegans. © 2017 by John Wiley & Sons, Inc.
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Affiliation(s)
- Nicolas J Lehrbach
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts.,Department of Genetics, Harvard Medical School, Boston, Massachusetts
| | - Fei Ji
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts.,Department of Genetics, Harvard Medical School, Boston, Massachusetts
| | - Ruslan Sadreyev
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts.,Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
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Abstract
Whole-genome sequencing provides a rapid and powerful method for identifying mutations on a global scale, and has spurred a renewed enthusiasm for classical genetic screens in model organisms. The most commonly characterized category of mutation consists of monogenic, recessive traits, due to their genetic tractability. Therefore, most of the mapping methods for mutation identification by whole-genome sequencing are directed toward alleles that fulfill those criteria (i.e., single-gene, homozygous variants). However, such approaches are not entirely suitable for the characterization of a variety of more challenging mutations, such as dominant and semidominant alleles or multigenic traits. Therefore, we have developed strategies for the identification of those classes of mutations, using polymorphism mapping in Caenorhabditis elegans as our model for validation. We also report an alternative approach for mutation identification from traditional recombinant crosses, and a solution to the technical challenge of sequencing sterile or terminally arrested strains where population size is limiting. The methods described herein extend the applicability of whole-genome sequencing to a broader spectrum of mutations, including classes that are difficult to map by traditional means.
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Itani OA, Flibotte S, Dumas KJ, Moerman DG, Hu PJ. Chromoanasynthetic Genomic Rearrangement Identified in a N-Ethyl-N-Nitrosourea (ENU) Mutagenesis Screen in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2015; 6:351-6. [PMID: 26628482 PMCID: PMC4751554 DOI: 10.1534/g3.115.024257] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 11/28/2015] [Indexed: 12/18/2022]
Abstract
Chromoanasynthesis is a recently discovered phenomenon in humans with congenital diseases that is characterized by complex genomic rearrangements (CGRs) resulting from aberrant repair of catastrophic chromosomal damage. How these CGRs are induced is not known. Here, we describe the structure and function of dpDp667, a causative CGR that emerged from a Caenorhabditis elegans dauer suppressor screen in which animals were treated with the point mutagen N-ethyl-N-nitrosourea (ENU). dpDp667 comprises nearly 3 Mb of sequence on the right arm of the X chromosome, contains three duplications and one triplication, and is devoid of deletions. Sequences from three out of the four breakpoint junctions in dpDp667 reveal microhomologies that are hallmarks of chromoanasynthetic CGRs. Our findings suggest that environmental insults and physiological processes that cause point mutations may give rise to chromoanasynthetic rearrangements associated with congenital disease. The relatively subtle phenotype of animals harboring dpDp667 suggests that the prevalence of CGRs in the genomes of mutant and/or phenotypically unremarkable animals may be grossly underestimated.
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Affiliation(s)
- Omar A Itani
- Institute of Gerontology, University of Michigan Medical School, Ann Arbor, Michigan 48109 Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109 Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Stephane Flibotte
- Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Kathleen J Dumas
- Institute of Gerontology, University of Michigan Medical School, Ann Arbor, Michigan 48109 Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109 Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Donald G Moerman
- Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Patrick J Hu
- Institute of Gerontology, University of Michigan Medical School, Ann Arbor, Michigan 48109 Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109 Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109
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Liu J, Chin-Sang ID. C. elegans as a model to study PTEN's regulation and function. Methods 2014; 77-78:180-90. [PMID: 25514044 DOI: 10.1016/j.ymeth.2014.12.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 12/04/2014] [Accepted: 12/05/2014] [Indexed: 02/06/2023] Open
Abstract
PTEN (phosphatase and tensin homolog deleted on chromosome 10) has important roles in tumor suppression, metabolism, and development, yet its regulators, effectors, and functions are not fully understood. DAF-18 is the PTEN ortholog in Caenorhabditis elegans. DAF-18's role is highly conserved to human PTEN, and can be functionally replaced by human PTEN. Thus C. elegans provides a valuable model to study PTEN. This review assesses current and emerging methods to study DAF-18's regulators and functions in C. elegans. We propose genetic modify screens to identify genes that interact with daf-18/PTEN. These genes are potential targets for anticancer drug therapies. We also provide a review on the roles DAF-18/PTEN has during C. elegans development and how studying these physiological roles can provide mechanistic insight on DAF-18/PTEN function.
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Affiliation(s)
- Jun Liu
- Department of Biology, Queen's University, 116 Barrie St., Kingston, ON K7L 3N6, Canada.
| | - Ian D Chin-Sang
- Department of Biology, Queen's University, 116 Barrie St., Kingston, ON K7L 3N6, Canada.
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Affiliation(s)
- Arjumand Ghazi
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States; Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States; Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
| | - Judith Yanowitz
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States; Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States; Department of Obstetrics and Gynecology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
| | - Gary A Silverman
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States; Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
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